Journal of Energy Storage 35 (2021) 102217
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Journal of Energy Storage
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A review of recycling spent lithium-ion battery cathode materials using
hydrometallurgical treatments
Joey Chung-Yen Jung a, *, Pang-Chieh Sui b, Jiujun Zhang a, *
a
b
Institute for Sustainable Energy / College of Sciences, Shanghai University, Shanghai 200444, China
Research Center for Electrochemical Energy Materials and Devices, Sichuan Energy Internet Research Institute, Tsinghua University, Chengdu, Sichuan 610213, China
A R T I C L E I N F O
A B S T R A C T
Keywords:
Lithium-ion battery
Spent cathode material
Recycling
Hydrometallurgy
With the increasing market share of lithium-ion battery in the secondary battery market and their applications in
electric vehicles, the recycling of the spent batteries has become necessary. The number of spent lithium-ion
batteries grows daily, which presents a unique business opportunity of recovering and recycling valuable
metals from the spent lithium-ion cathode materials. Various metals including cobalt, manganese, nickel,
aluminum, and lithium can be extracted from these materials through leaching with chemicals such as hydro­
chloric acid (HCl), nitric acid (HNO3 ), sulfuric acid (H2 SO4 ), oxalate (H2 C2 O2 ), DL-malic acid (C4 H5 O6 ), citric
acid (C6 H8 O7 ), ascorbic acid (C6 H8 O6 ), phosphoric acid (H3 PO4 ) or acidithiobacillus ferrooxidans. This paper
provides a comprehensive review on the available hydrometallurgical technologies for recycling spent lithiumion cathode materials. The recycling processes, challenges and perspectives reported to date and recycling
companies in the market are summarized. To accelerate the development of battery recycling technology toward
commercialization, some potential research directions are also proposed in this paper.
1. Introduction
Electric vehicles play a critical role in meeting the environmental
goals of the sustainable development to reduce local air pollution and to
address climate change. It is estimated it will reach 245 million electric
vehicles in 2030, more than 30 times above today’s 7.2 million level.
[1]. Electric vehicles are powered by one or more electric motors. They
receive electricity by plugging into the grid and store it in batteries.
Lithium-ion batteries have been recognized as one type of the most
practical and commercially feasible batteries for electric vehicles [2].
Advances in the commercial development of lithium-ion batteries have
spawned significant growth of demand on lithium (Li), cobalt (Co),
manganese (Mn), and nickel (Ni). For example, in 2000, the world
mined production of cobalt was only 33,300 metric tons (mt) per year,
with the majority of product used for super-alloys in high temperature
services. In 2019, the world mine production of cobalt was approxi­
mately 140,000 mt per year (as metal), of which 80% were destined for
the lithium-ion battery market [3]. As 98% of the cobalt production
worldwide is a by-product of copper (Cu) and nickel mining, the in­
crease in cobalt demand leads to a shortage in supply and a dramatic
increase in price, evidenced by the 311% price hike between 2016 (USD
$ 12.01/lb) and 2018 (USD $ 37.43/lb) [4].
In 2019, it was estimated that lithium ion batteries for electric
vehicle production consumed about 19000 mt of cobalt, 17000 mt of
lithium, 22000 mt of manganese, and 65000 mt of nickel. With the
projection of 245 million electric vehicles by 2030, the required cobalt
demand expands to about 180,000 mt/year, lithium to around 185,000
mt/year, manganese to 177,000 mt/year, and nickel to 925,000 mt/year
[5]. Meanwhile, comparing the data shown in Fig. 1 that published in
Mineral Commodity Summaries 2017 and 2020 by U.S. Geological
Survey, lithium reserves have decreased from 45,860,000 mt to 16,585,
000 mt [3, 5] as shown in Fig. 1.
To secure lithium resources, vehicle manufacturers and governments
are forging alliances to safeguard their needs as lithium is treated as the
future energy source. For example, Toyota Corporations, Magna Inter­
national, Mitsubishi, and Tesla have forged partnerships with lithium
exploration companies and have invested large sums to develop lithium
deposits around the world. As the upcoming mass adoption of electric
vehicles causes a significant supply crunch on lithium-ion battery ma­
terials, automobile original equipment manufacturers (OEMs) also start
to look at overcoming the possible shortage of lithium-ion battery ma­
terials through reuse of lithium-ion batteries retired from electric vehi
* Corresponding authors.
E-mail addresses: jjung@shu.edu.cn (J.C.-Y. Jung), jiujun.zhang@i.shu.edu.cn (J. Zhang).
https://doi.org/10.1016/j.est.2020.102217
Received 28 October 2020; Received in revised form 20 December 2020; Accepted 22 December 2020
Available online 27 January 2021
2352-152X/© 2021 Elsevier Ltd. All rights reserved.
J.C.-Y. Jung et al.
Journal of Energy Storage 35 (2021) 102217
cles for other applications such as electricity energy storage (battery
second use) and through recycling lithium-ion batteries to obtain the
important metals once they have finished their lifecycle. Industry ana­
lysts have predicted that by 2030, the worldwide number of spent
lithium-ion batteries will hit 2 million metric tons per year [6]. Recy­
cling these spent lithium-ion batteries can provide a source of
lithium-ion battery materials such as lithium, nickel, cobalt, manganese,
and aluminum [7]. Spent lithium-ion batteries recycling processes
usually first go through sorting the batteries by battery chemistries
followed by deep discharge to avoid violent reaction from the charged
electrode materials exposed to the air. During discharge, positive
charged lithium ions move from anode through electrolyte and sepa­
rator to cathode, making spent cathode material enriched with lithium.
The discharged batteries then go through physical dissemble, as shown
in Fig. 2, before undergone electrolyte extraction, high-temperature
melting-and-extraction, smelting, direct recycling, or chemical/hy­
drometallurgy extraction. Spent cathode materials can be separated
from current collectors by using dimethylacetamide, N-methyl-pyr­
olidinone, N-Methyl-2-pyrrolidone (NMP), or acetone at 60 ◦ C to
dissolve the binder. Chow et al. [8] reported that battery cathode ma­
terials can be detached from aluminum foil by soaking cathodes in mild
sulfuric acid (H2 SO4 ). Zhang et al. [9] reported a patented complex
aqueous peeling agent, namely exfoliating and extracting solution
(AEES), which could weaken the mechanical interlocking force and
Coulombic force between cathode materials and foils, and separately
recovered Al foil, Cu foil, and active materials.
Li et al. [10] investigated replacing organic NWP solvent with water
during electrode fabrication in order to simplify the recycling process,
and found that water-processed electrodes exhibited a comparable
electrochemical performance with NMP-based electrode and the elec­
trode materials were easier to recycle.
Other than cathode material enriched in lithium, anode material like
lithium titanate (LTO) and battery electrolyte, LiPF6 , LiBF4 , or LiClO4 ,
also enrich with lithium. Recycling cathode material, LTO, and elec­
trolyte can provide a sustainable lithium source.
LTO can be treated with hydrochloric acid (HCl) to extract Li and
recover titanium as titanium oxide (TiO2 ) [11, 12]. Electrolyte can be
extracted by vacuum distillation or extracted by sub- and supercritical
carbon dioxide (CO2 ) extraction using a flow-through or batch autoclave
setup. Sub- and supercritical CO2 extraction has demonstrated that up to
90% of the electrolyte can be recovered from spent lithium ion batteries.
[13-16]. The recovered electrolyte contented conducting salt, and the
decomposed electrolyte can be purified with a weakly basic anion ex­
change resin [16].
As identified, the spent cathode material can contain up to 7 wt
percent (wt%) lithium, as shown in Fig. 3. Also shown in Fig. 3, the spent
lithium nickel cobalt aluminum (NCA) battery contains up to 31wt% of
cathode material [17].
Furthermore, Fig. 4 shows the main components of lithium cobalt
oxide (LCO) battery, lithium nickel manganese cobalt oxide (NMC)
battery, and lithium iron phosphate (LFP) battery, where the cathode
material accounts for 41wt%, 26wt%, and 25wt% of the battery,
respectively. [18] Recycling these spent cathode materials can not only
recycle lithium but also recover nickel, cobalt, manganese, and
aluminum.
2. Hydrometallurgy treatments
Hydrometallurgy extraction process, or chemical leaching, which is
practiced commercially in China, for example, offers a less energyintensive alternative and lower capital costs. These processes
employed regents such as hydrochloric acid (HCl), nitric acid (HNO3 ),
sulfuric acid (H2 SO4 ), and hydrogen peroxide (H2 O2 ) for extracting and
separating cathode metals, generally run below 100 ◦ C and can recover
lithium in addition to the other transition metals [19].
This paper reviews the various hydrometallurgy methods developed
in the recent ten years for recycling cathode materials of lithium-ion
batteries from various battery chemistries including Lithium Cobalt
Dioxide, LiCoO2 (LCO), Lithium Manganese Dioxide, LiMn2 O4 (LMO),
Lithium Nickel Manganese Cobalt Oxide, LiNiMnCoO2 (NMC), and
Lithium Nickel Cobalt Aluminum Oxide, LiNiCoAlO2 (NCA), and
Lithium iron Phosphate LiFePO4 (LFP), to recover cobalt, nickel, man­
Fig. 1. World Lithium Reserves by U.S. Geological Survey [3, 5].
2
J.C.-Y. Jung et al.
Journal of Energy Storage 35 (2021) 102217
Fig. 2. Battery physical dissemble.
Fig. 3. Components of a lithium-ion battery with NCA cathode [17].
Fig. 4. Components of a lithium-ion battery with LCO, NMC, and LFP cathode [18].
ganese, and lithium. Fig. 5 shows the hydrometallurgy process for
recycling battery cathode materials. The process can be categorized into
4 sections, which are leaching, impurity removal, metal like Ni, Co, Mn
recovery, and lithium recovery. As shown in Fig. 5, the spent cathode
material is first slurried with weak acid and then transferred to the
leaching tanks. Acid and reducing agent are then added into the leaching
tanks to leach out Li+ , Ni2+ , Co2+ , Mn2+ , Fe2+ , and Al3+ . In the impurity
removal section, the unwanted impurity will be removed through pH
adjustment. After impurity removal, the solution is transferred to metal
recovery section where metal can be recovered via a chemical precipi­
tation or a solvent extraction. After metal recovery, the remaining
lithium enriched solution is transferred to the lithium recovery section
3
J.C.-Y. Jung et al.
Journal of Energy Storage 35 (2021) 102217
Fig. 5. Schematic of the hydrometallurgy process for recycling battery cathode materials.
where lithium can be recovered by chemical precipitation using sodium
carbonate or by crystallization by distillation.
The valuable metals, mainly cobalt, manganese, nickel, and lithium
can be extracted from the spent lithium-ion cathode materials through
leaching treatment, as summarized in Table 1.
Once the valuable metals have been leached, the metals can be
recovered through a series of processes including sedimentation, pre­
cipitation, and solvent extraction. After the leaching treatment, the
recovered materials can be reformulated to regenerate lithium cathode
material.
The leached Co2+ , Mn2+ , and Ni2+ could be recovered through se­
lective precipitation as metal hydroxides could slowly increase the
leachate pH using sodium hydroxide (NaOH) [22]. The precipitation of
Mn2+ , Ni2+ , and Co2+ began at pH of 1, 2, and 3, and was completely
precipitated at pH 12, 8, and 10, respectively. The leached Li+ could be
precipitated as lithium carbonate via adding sodium carbonate
(Na2 CO3 ) after the leachate clear of Co2+ , Mn2+ , and Ni2+ .
Alternatively, the manganese can be selectively recovered from the
leachate using potassium permanganate (KMnO4 ) via the following
redox reaction [24]:
3Mn2+ +2MnO−4 +2H2 O→5MnO2 +4H+
2.1. Hydrochloric acid and sodium hydroxide as hydrometallurgy
treatment reagents
The optimum operating conditions of Mn precipitation via KMnO4
were having a molar ratio of Mn2+ to KMnO4 at 2, pH at 2, and an
operation temperature at 40 ◦ C. After removing Mn from the leachate,
the Ni could be selectively recovered using dimethylglyoxime
(C4 H8 N2 O2 ) and ammonia (NH3 ) solution via adding 28 wt% NH3 so­
Zhang et al. [20], Contestabile et al. [21], and Takacova et al. [22]
investigated the leaching of spent lithium cobalt dioxide (LiCoO2 )
cathode material with hydrochloric acid (HCl). Based on the experi­
mental results and literature reports, the extraction of cobalt and lithium
could achieve 100% at 80 ◦ C with either 2 M or 4 M HCl within 90 min
and 60 min, respectively. Wang et al. [23] achieved a leaching efficiency
of more than 99% of Cobalt (Co), manganese (Mn), Nickel (Ni), and
lithium (Li) with 4 M HCl at 80 ◦ C and 60 min of leaching time on
LiCoO2 , LiMn2 O4 , and LiNi1/3 Mn1/3 Co1/3 O2 .
The hydrochloric acid leaches Co, Mn, Ni, and Li according to the
following reactions [20, 21-23]:
2LiCoO2 +8HCl→2LiCl + 2CoCl2 +2H2 O + Cl2
(1)
2LiMn2 O4 +16HCl→2LiCl + 4MnCl2 +8H2 O + 3Cl2
(2)
(4)
lution into the leachate to from Ni(NH3 )2+
which then reacted with
6
C4 H8 N2 O2 to form a red precipitate. Nickel in the red precipitate could
then be re-leached into solution with 4 M HCl and then precipitated with
NaOH to form nickel hydroxide (Ni(OH)2 ). The optimum operating
conditions for Ni recovery using C4 H8 N2 O2 and NH3 were having a
molar ratio of C4 H8 N2 O2 to Ni(NH3 )2+
6 at 2 and pH at 9. Co could then be
recovered as cobalt hydroxide by raising the leachate pH to 11 via
NaOH, and Li was recovered as Li2 CO3 via adding Na2 CO3 .
Fig. 6 illustrates the recover flow sheet with the two alternatives. It
should be noted that the employed HCl as a leaching agent possibly gen­
erates toxic chlorine gas (Cl2 ) as a byproduct as shown in Eqs. (1) to (3).
6LiNi1/3 Mn1/3 Co1/3 O2 +24HCl→6LiCl + 2NiCl2 +2MnCl2 +2CoCl2 +12H2 O + 3Cl2
4
(3)
J.C.-Y. Jung et al.
Journal of Energy Storage 35 (2021) 102217
Table 1
Reported Leaching Processes for Recycling Spent Cathode Materials of Lithium-ion batteries with LCO, LMO, NMC, and NCA chemistries.
No
Leaching Treatment
A
1
Inorganic Leaching Agent
HCl
(4 mol L − 1)
2
HCl
3
HCl
4
HNO3
(2 mol L − 1)
HNO3
(1 mol L − 1)
(2 mol L − 1)
(4 mol L − 1)
HNO3
(1 mol L − 1)
7
HNO3
(1 mol L − 1)
8
H2 SO4
(8.0 Vol%)
5
6
H2 SO4
(2 mol L − 1)
H2 SO4
(3 mol L − 1)
11
H2 SO4
(6.0 Vol%)
12
H2 SO4
(4 mol L − 1)
H2 SO4
(2 mol L − 1)
9
10
13
14
15
H2 SO4
(2 mol L − 1)
H2 SO4
(2 mol L − 1)
H2 SO4
(2 mol L − 1)
H2 SO4
(3 mol L − 1)
18
H2 SO4
(6.0 Vol%)
19
H2 SO4
(2 mol L − 1)
H2 SO4
(4 mol L − 1)
16
17
H2 SO4
(3 mol L − 1)
22
H2 SO4
(4 mol L − 1)
23
NH3
20
21
Leach Temp ( ◦ C)
Leach Efficiency (%)
Reducing Agent
N/A
80
Li
100
Co
100
N/A
60–80
100
100
N/A
80
100
100
N/A
80
100
H2 O2 (1.7 Vol%)
75
85
85
26
H2 O2 (1.7 Vol%)
75
85
85
27
H2 O2 (1.0 Vol%)
80
100
100
28
N/A
80
95
80
7
H2 O2 (5.0 Vol%)
Reference Number [#]
Mn
20, 21
22
100
23
95
25
80
99
99
30
N/A
70
98
98
32
H2 O2 (4.0 Vol%)
65
37
55
33
H2 O2 (10.0 Vol%)
85
96
95
34
H2 O2 (6.0 Vol%)
60
99
99
35
H2 O2 (15.0 Vol%)
75
100
100
36
H2 O2 (2.0 Vol%)
60
88
96
37
H2 O2 (5.0 Vol%)
75
94
93
38
H2 O2 (3.0 Vol%)
70
100
100
39
H2 O2 (1.0 Vol%)
60
90
90
31
H2 O2 (10.0 Vol%)
70
80
98
97
SO2
40–80
99
99
H2 O2 (3.0 Vol%)
Na2 S2 O3 (0.25molL− 1)
40
97
41
44
42, 43
50–80
61
81
58, 59
40
99
99
72
90
100
100
90
100
92
Reducing Agent
N/A
80
98
98
57
H2 O2 (2.0 Vol%)
90
94
93
62
(1.5 mol L − 1)
H2 O2 (3.0 Vol%)
80
98
99
63
(1.5 mol L − 1)
Grape seed (0.6 g/g)
80
99
92
64
(1.5 mol L − 1)
Glucose
55
100
98
65
(1.5 mol L − 1)
Electrochemical reduction
60
100
99
C6 H8 O7 H2 O
(Citric Acid)
(1.25 mol L − 1)
H2 O2 (1.0 Vol%)
90
100
90
68, 69
34
C6 H8 O6
(Ascorbic Acid)
(1.25 mol L − 1)
70
98
97
73
35
C6 H6 O3 S
50
99
97
74
D
36
37
Bioleaching Agent
Acidithiobacillus Ferrooxidans
Mesophilic potential sulfur-oxidizing bacteria
30
25
10
65
75
79
(0.7 mol L − 1)
B
25
H3 PO4
Inorganic Leaching Agent
H2 SO4
26
H3 PO4
(0.2 mol L − 1)
28
C4 H5 O6
(DL-malic Acid)
(1.5 mol L − 1)
29
C4 H5 O6
(DL-malic Acid)
30
C4 H5 O6
(DL-malic Acid)
31
C4 H5 O6
(DL-malic Acid)
32
C4 H5 O6
(DL-malic Acid)
33
24
C
27
Organic Leaching Agent
H2 C2 O2 2H2 O
(1.5 mol L − 1)
(1.3 mol L − 1)
Na2 SO4
H2 O2 (4.0 Vol%)
Organic Reducing Agent
Glucose
C6 H8 O7 (0.4 mol L − 1)
CH2 O2 (1.5 mol L − 1)
Additives
S + Fe
2.2. Nitric acid as a hydrometallurgy treatment reagent
(5)
They stated that 100% of Li and up to 95% of Mn could be leached
with 2 M HNO3 at 80 ◦ C in 120 min. Lee et al. [26, 27], and Li et al. [28]
studied the reductive leaching of LiCoO2 and LiMn2 O4 using a lower
concentration of nitric acid (HNO3 ) with hydrogen peroxide (H2 O2 ). The
leaching reaction of LiMn2 O4 is illustrated as follows:
2LiMn2 O4 +10HNO3 + H2 O2 →2LiNO3 +4Mn(NO3 )2 +6H2 O + 2O2
99
71
66, 67
Their studies showed that when leaching with 1 M HNO3 , the
leaching efficiency of Co and Li could reach to 40% and 75%, respec­
tively. The leaching efficiency was improved significantly when adding
H2 O2 to the leachate. Lee et al. [27] reported that with 1 M HNO3 and
1.7 vol% H2 O2 at 75 ◦ C, up to 99% of Co and Li could be leached in 30
min. They believed the improvement of leaching efficiency was due to
the addition of H2 O2 acting as a reducing agent to reduce Co3+ to Co2+ ,
Mn3+ to Mn2+ , which were readily dissolved in HNO3 .
Using lower concentration of HNO3 in the leach is of particular in­
terest to the battery recycle industry as it reduces the reagent con­
sumption in the following material recovery steps. Fig. 7 shows the flow
sheets of HNO3 leach and HNO3 + H2 O2 leach. The drawback of using
HNO3 to leach is that leaching with HNO3 generates NOx . NOx , if
Castillo et al. [25] studied the leaching of LiMn2 O4 from spent
lithium-ion battery using nitric acid (HNO3 ). The leaching reactions are
illustrated as follows:
LiMn2 O4 +10HNO3 →2Mn(NO3 )2 +LiNO3 +5NO2 +5H2 O + 2O2
46, 47
92
(6)
5
J.C.-Y. Jung et al.
Journal of Energy Storage 35 (2021) 102217
Fig. 6. Two alternative flowsheets (Red and Blue) to recover Li, Mn, Co, and Ni from HCl leach [20, 21, 22, 24].
released into the atmosphere, is a prominent air pollutant thus needs to
be captured for treatment. On the other hand, NOx can be collected to
react with water to generate HNO3 and feed back to the leach operation,
which is worth of further investigation.
2LiCoO2 +3H2 SO4 + H2 O2 →Li2 SO4 +2CoSO4 +4H2 O + O2
(10)
Leaching spent Li-ion battery cathode material with sulfuric acid
(H2 SO4 ) is normally slow. For LiCoO2 , the bonding nature between
oxygen and cobalt entities (O–Co-O) is chemical and hence comparably
very strong. The breaking of these bonds requires significantly more
energy [29].
Sun et al. [30] reported using H2 SO4 to leach spent LiCoO2 . Leaching
LiCoO2 with H2 SO4 involved the reduction of Co3+ in the solid phase to
Co2+ in the aqueous phase. It was believed CoO2 first formed Co3 O4
solid which required excess of H2 SO4 to be converted to soluble CoSO4
as showed in the following reactions [31]:
With the addition of 5 vol% H2 O2 , the leaching efficiency of cobalt
could be increased to 99%. This was because H2 O2 could help break the
strong chemical bond between Co and O. In the absence of a reducing
agent, O from LiCoO2 was oxidized into O2 , leading to a low Co leaching
efficiency. With H2 O2 acting as a reducing agent, Co3+ in the solid
species was reduced to Co2+ in the aqueous phase. As Co2+ was readily
dissolved in aqueous solution, the Co leaching efficiency was much
higher. On the other hand, Li+ is readily dissolved in aqueous solution
thus the addition of H2 O2 showed a negligible impact on the leaching
efficiency of lithium, which was also reported by Ferreira [31]. This
behavior could be expended to other spent lithium cathode material.
Nayl et al. [32] reported that in the leaching LiCoO2 and a LiMnO2 with
2 M H2 SO4 , only 51.6% of Mn and about 42.7% of Co were obtained.
With the addition of 4% H2 O2 , 97.8% of Mn and 99.6% of Co were
leached. The equations for LiMnO2 leach can be expressed as follows:
4LiCoO2(s) +3H2 SO4 →Co3 O4(s) +2Li2 SO4(aq) +CoSO4(aq) +3H2 O + 1 / 2O2(g)
4LiMnO2 +6H2 SO4 →2Li2 SO4 +4MnSO4 +6H2 O + O2
(11)
2LiMnO2 +3H2 SO4 + H2 O2 →Li2 SO4 +2MnSO4 +4H2 O + O2
(12)
2.3. Sulfuric acid as a hydrometallurgy treatment reagent
(7)
Co3 O4(s) +3H2 SO4 →3CoSO4(aq) +3H2 O + 1 / 2O2(g)
(8)
Dorella et al. [33], Chen et al. [34], Kang et al. [35], Shin et al. [36],
Zhu et al. [37], Swain et al. [38], Nan et al. [39], Chen et al. [40] re­
ported the leaching of spent lithium cathode materials with various
H2 SO4 and H2 O2 concentrations. Based on their studies, the optimum
conditions could be concluded as follows: 2 M H2 SO4 , 5vol% H2 O2 ,
leaching time of 60 – 90 min at temperature between 60 ◦ C to 80 ◦ C, and
a solid/liquid ratio of 50 gL− 1.
Yang et al. [41] reported a leaching and direct precipitation process
to regenerate LiNi0.6 Co0.2 Mn0.2 O2 cathode material with carbonate
co-precipitation. Leaching efficiencies of 97.8% for Li, 98.1% for Ni,
96.5% for Co, and 97.0% for Mn were obtained with 3 M H2 SO4 , 3vol%
H2 O2 , and leaching time 60 min at 80 ◦ C. The regenerated
LiNi0.6 Co0.2 Mn0.2 O2 cathode could produce a great initial discharge
Total:
4LiCoO2 +6H2 SO4 →2Li2 SO4 +4CoSO4 +6H2 O + O2
(9)
Sun et al. [30] discovered that with 2 M H2 SO4 , leaching efficiency of
76% could be achieved. With 3 M H2 SO4 at 70 ◦ C, Nan et al. [32] could
achieve 99% leaching efficiency. However, higher acid concentration
was not favoured as it increased the overall reagent consumption in the
overall recovery process. To increase leaching efficiency with lower acid
concentration, Sun et al. [30] reported that adding H2 O2 as a reductant
during the leaching process to reduce Co3+ to Co2+ could facilitate the
forward reaction as shown in the following reaction:
6
J.C.-Y. Jung et al.
Journal of Energy Storage 35 (2021) 102217
of Co and 99.2% of Li leach efficiencies could be obtained. The leaching
time could be shortening while maintaining 99.6% of Co and 99.8% of Li
leach efficiency with 3 M H2 SO4 and SO2 sparging at 70 – 80 ◦ C for 60
min, solid/liquid ratio at 1:8, and 0.15 MPa pressure. However, it was
believed that when leach with SO2 , not only lithium sulfate (Li2 SO4 ),
cobaltous sulfate (CoSO4 ) but also lithium dithionate (Li2 S2 O6 ), cobal­
tous dithionate (CoS2 O6 ) could also be generated.
Kemetco Research Inc. and American Manganese Inc. disclosed using
SO2 in combination with H2 SO4 to leach LiCoO2 , LiMn2 O4 , lithium
nickel manganese cobalt oxide (LiNi0.33 Mn0.33 Co0.33 O2 ), and lithium
nickel cobalt aluminum oxide (LiNi0.8 Co0.15 Al0.05 O2 ) [45]. While close
to 100% extraction of Li, Co, Mn, nickel (Ni), and Aluminum (Al) were
achieved, it was believed that dithionate was presented in all leach
processes as follows:
For LiCoO2 :
2LiCoO2 +SO2 +2H2 SO4 →Li2 SO4 +2CoSO4 +2H2 O
(14)
2LiCoO2 +3SO2 +2H2 SO4 →Li2 SO4 +2CoS2 O6 +2H2 O
(15)
2LiCoO2 +4SO2 +2H2 SO4 →Li2 S2 O6 +2CoS2 O6 +2H2 O
(16)
For LiNi0.33 Mn0.33 Co0.33 O2 :
2LiNi0.33 Mn0.33 Co0.33 O2 +SO2 +2H2 SO4 →Li2 SO4
+ 2(Ni, Co, Mn)SO4 +2H2 O
(17)
2LiNi0.33 Mn0.33 Co0.33 O2 +3SO2 +2H2 SO4 →Li2 SO4
+ 2(Ni, Co, Mn)CoS2 O6 +2H2 O
2LiNi0.33 Mn0.33 Co0.33 O2 +4SO2 +2H2 SO4 →Li2 S2 O6
+2(Ni,Co,Mn)S2 O6 +2H2 O
(18)
(19)
(Ni,Co,Mn)SO4 and (Ni,Co,Mn)S2 O6 represent a mixed metal sulfate
and a mixed metal dithionate respectively.
For LiNi0.8 Co0.15 Al0.05 O2 :
2LiNi0.8 Co0.15 Al0.05 O2 +SO2 +2H2 SO4 →Li2 SO4 + 2(Ni, Co, Al)SO4 +2H2 O
(20)
2LiNi0.8 Co0.15 Al0.05 O2 +3SO2 +2H2 SO4 →Li2 SO4
+ 2(Ni, Co, Al)CoS2 O6 +2H2 O
2LiNi0.8 Co0.15 Al0.05 O2 +4SO2 +2H2 SO4 →Li2 S2 O6 +2(Ni, Co, Al)S2 O6 +2H2 O
(22)
Fig. 7. HNO3 leach flowsheets [25-28].
(Ni, Co, Al)SO4 and (Ni, Co, Al)S2 O6 represent a mixed metal sulfate
and a mixed metal dithionate respectively.
Granata et al. [46] and Pagnanelli et al. [47] reported using glucose
(C6 H12 O6 ) as reducing agent in H2 SO4 leaching according to the
following reaction:
capacity of 173.4 mAh/g at 0.1C discharge under a calcination tem­
perature of 850 ◦ C and 93.6% capacity retention after 100 cycles at 1C.
Wang et al. [42] and Vieceli et al. [43] reported the leaching of spent
lithium-ion cathode materials using H2 SO4 and sodium thiosulfate
(Na2 S2 O3 ) as the reducing agent. It concluded that the leaching effi­
ciency of Co and Li could be increased at higher acid concentration. The
leaching rates of Co, Cu, and Li were increased first and then decreased
afterwards with increasing Na2 S2 O3 concentration. The optimum con­
ditions, at which 99.95% Co and 99.71% Li were obtained, were 3 M
H2 SO4 and 0.25 M Na2 S2 O3 at 90 ◦ C for 3 h with liquid/solid ratio at
15:1. The following illustrates the reaction equation:
8LiCoO2 +Na2 S2 O3 +11H2 SO4 →4Li2 SO4 +8CoSO4 +Na2 SO4 +11H2 O
(21)
24LiCoO2 + C6 H12 O6 +36H2 SO4 →12Li2 SO4 +24CoSO4 +6CO2 +42H2 O
(23)
Glucose is a low cost and non-hazardous chemical and was first
proposed for Mn reducing leaching of pyrolusite ores [48, 49] and zinc
manganese dioxide alkaline battery [50]. It was discovered that the
leaching solution contained high concentrations of formic acid along
with mono-carboxylic poly‑hydroxyl acids like glyceric acid and glycolic
acids, suggesting that glucose was oxidized. The use of glucose as the
reducing agent should be an innovative and environmentally friendly
option in H2 SO4 leaching of spent lithium-ion battery cathode materials.
Pagnanelli et al. [47] reported that 88% extraction of Co could be ob­
tained with glucose as a reducing agent. The leached lithium, cobalt, and
other metals can be recovered through many methods such as chemical
precipitation, solvent extraction, and crystallization. In this regard,
(13)
Long et al. [44] introduced SO2 as the reducing agent in the H2 SO4
leach. The advantages of using SO2 were found to be faster reaction rate,
higher initial leach pH, low consumption of H2 SO4 , and high leaching
efficiency. They reported that with 1.5 M H2 SO4 and SO2 sparging at 40
– 50 ◦ C for 3 h, solid/liquid ratio at 1:12, and 0.15 MPa pressure, 99.1%
7
J.C.-Y. Jung et al.
Journal of Energy Storage 35 (2021) 102217
Fig. 8. H2 SO4 Leach Flowsheet [30-32,33-50].
Fig. 8 shows the flowsheets.
Chemical precipitation can selectively precipitate the metals. For
example, for leachate containing Mn2+ , Ni2+ , and Co2+ , precipitation
can be achieved using sodium hydroxide (NaOH) and sodium sulfide
(Na2 S) based on each metal’s hydroxide solubility or sulfide solubility at
certain pH values. For example, in order to separate Mn from Ni and Co
in the solution, NaOH and Na2 S solutions were used based on different
hydroxide solubility and sulfide solubility of metals at a certain pH [42,
43]. For Mn precipitation, the concentrated Na2 CO3 solution was used.
For the final stage, the Na2 CO3 solid was used. Cobalt, nickel and
manganese could be totally precipitated from the solution at pH above
10 and leaving on lithium in the solution.
Solvent extraction can be employed to selectively extract cobalt [51].
The extraction of metal was based on the following mechanism [52]:
−
+
M2+
Aq + AOrg + 2(HA)2Org →MA2 3HAOrg + HAq
a cobalt lithium enriched leachate. Nan et al. [54] used Acorga M5640
and Cyanex 272 to effectively extract 98% of the copper and 97% of the
cobalt from sulfate solution. Their work also demonstrated that Acorga
M5640 and Cyanex 272 could be recycled after striping with H2 SO4 .
Zhang et al. [20] conducted a batch solvent extraction using 0.90 M of
PC-88A with Kerosene at an O:A ratio of 0.85:1 and pH 6.7 to extract
cobalt from lithium enriched solution and found that 99.99% purity of
Co could be obtained after H2 SO4 stripping.
Zante et al. [55] used solvent extraction to individually extract Mn2+ ,
Co2+ , Ni2+ , and Li+ . Mn2+ was first removed using N,N,N’,N’-tetra
(noctyl) diglycolamide (TODGA) extractant diluted in an ionic liquid
and then stripped with water. Second, Co2+ was extracted using tri-hexyl
tetradecylphosphonium chloride ([P66614][Cl]) and then stripped with
water. Third, Ni2+ was recovered using deep eutectic solvents (DES)
made of carboxylic acids and lidocaine and stripped with sodium oxa­
late. Finally, Li+ was precipitated by chemical precipitation. Sun et al.
[56] selectively extracted lithium using benzo-15-crown-5 ether
(B15C5). At pH of 6.0, temperature of 30 ◦ C, and 120 min of extraction
time, the extraction rate of Li+ was 37%, and the extraction rate of Ni2+
was 5.18%, and about zero for Co2+ and Mn2+ .
Crystallization to recover Co2+ was studied by Ferreira et al. [31],
who reported that by evaporating 85% H2 O from the leachate contain­
ing 11.3 g/L Co, 0.6 g/L Al, and 1.2 g/L Li, a purified monohydrated
CoSO4 ⋅H2 O was produced with only 0.4% Al, and 0.6% Li contamina­
tion. Granata et al. [46] recovered 80% lithium as carbonate by evap­
orating 80% of H2 O to obtain a purity higher than 98% Li2 CO3 crystal
after removing Co2+ , Ni2+ , and Mn2+ through precipitation using
carbonate
(24)
where A−Org + 2(HA)2Org represents the extractant saponified by the
following reaction:
/
+
Na+
Aq + 1 2(HA)2Org →NaAOrg + HAq
(25)
The efficiency of metal extraction was calculated by the distribution
coefficient of metal in aqueous and organic phases. When the solution
containing Co2+ and Ni2+ , the distribution coefficient (D) can be illus­
trated as follows:
/
DCo = [Co]Org [Co]aq
(26)
/
DNi = [Ni]Org [Ni]aq
(27)
2.4. Oxalate as a hydrometallurgy treatment reagent
where metal concentration in organic phase can be determined by a
mass balance considering the residual concentration in aqueous phase.
The index of extraction selectivity (β) of Co over Ni can then be calcu­
lated by the following equation:
β = DCo /DNi
Oxalate is a common organic acid and can be dissolved in warm H2 O.
Sun et al. [57] used oxalate to leach cobalt and lithium into leachate,
where cobalt was then precipitate out as cobalt oxalate.
The reaction between LiCoO2 and oxalate is a multiphase reaction.
The following shows the leaching reactions using oxalate:
(28)
Lupi et al. [53] reported that Co could be extract from nickel with
Cyanex 272 [di-(2,4,4-trimethylpentyl) phosphoric acid] in Kerosene.
Granata et al. [39] tested two extractants, D2HEPA and Cyanex 272, and
found that Cyanex 272 could selectively extract Co completely before
extracting Ni. Dorella et al. [33] used Cyanex 272 to extract cobalt from
7H2 C2 O4 + 2LiCoO2(s) →2LiHC2 O4 + 2Co(HC2 O4 )2 + 4H2 O + 2CO2(g)
4H2 C2 O4 +2LiCoO2(s) →Li2 C2 O4 +2CoC2 O4(s) +4H2 O + 2CO2(g)
8
(29)
(30)
J.C.-Y. Jung et al.
Journal of Energy Storage 35 (2021) 102217
During the oxalate leaching process, carbon dioxide was evolved
from oxalate that converted Co3+ to Co2+ then promoted the dissolution
of Co. Sun et al. [57] also investigated the addition of H2 O2 on pro­
moting the Co leaching efficiency through the following reactions:
soluble at pH from 8.5 to 10.5. As such, Ni2+ , Co2+ , Li+ , and Mn2+ can be
selectively recovered.
Zheng et al. [58] reported leaching NMC with NH3 , ammonium
sulfate (NH4 )2 SO4 and Na2 SO3 . Ni, Co and Li could be selectively
leached out from cathode scrap powder. With 4 M NH3 , 1.5 M
(NH4 )2 SO4 and 0.5 M Na2 SO3 at 353 K, 10 g/L pulp density and 300 min
of retention time, more than 98% of Ni, Co, and Li could be selectively
leached with 6.3% of Mn.
Wu et al. [59] reported that leaching 2% pulp density spent
Ni/Co/Al-containing material (NCA) with NH3 and Na2 SO3 and using
ammonia bicarbonate (NH4 HCO3 ) as a pH buffer could obtain 60.5%
leaching efficiency for Li, 81% for Co while Al was hardly leached.
6H2 C2 O4 + 2LiCoO2(s) + 3H2 O2 →2LiHC2 O4 + 2Co(HC2 O4 )2 + 6H2 O
+ 2O2(g)
(31)
3H2 C2 O4 +2LiCoO2(s) + H2 O2 →Li2 C2 O4 +2CoC2 O4(s) +4H2 O + O2(g)
(32)
The experimental data suggested that H2 O2 had little influence on
the leaching of LiCoO2 with oxalate. The oxalate leaching efficiency with
and without H2 O2 was 96.3% and 96.7%, respectively. They concluded
that the optimized leaching conditions using oxalate was 1.0 M oxalate
at 80 ◦ C for 120 min with solid/liquid ration of 50 g/L. Fig. 9 shows the
proposed flowsheet.
2.6. DL-malic acid as a hydrometallurgy treatment reagent
DL-malic acid is a natural organic acid and a member of the C4dicarboxylic acid family [60] with ionization constants of
K1 = 4.0 × 10− 4 and K2 = 9.0 × 10− 6 [61]. DL-malic acid degrades easily
under aerobic and anaerobic conditions thus its waste can be treated
easily. Li et al. [62] investigated leaching LiCoO2 with DL-malic acid.
The reaction between DL-malic acid and LiCoO2 is a multiphase reac­
tion. The following shows the leaching reactions:
2.5. Ammonia with sodium sulfite as the hydrometallurgy treatment
reagent
Leaching spent cathode material, Ni/Mn/Co containing cathode
material (NMC), with ammonia (NH3 ) requires sodium sulfite (Na2 O3 )
as a reductant to reduce Co3+ to Co2+ . The Ni2+ and Co2+ will react with
ammonia according to the following equations while Mn and ammonia
reaction is not favorable.
Ni2+ +nNH3 →Ni(NH3 )n 2+
Co2+ +nNH3 →Co(NH3 )n
Co(NH3 )n
2+
2+
is more soluble at pH around 9–11 while Ni(NH3 )n
12C4 H6 O5(aq) +4LiCoO2(S) →4LiC4 H5 O5(aq) +4Co(C4 H5 O5 )2(aq) +6H2 O + O2(g)
(35)
2+
12C4 H5 O−5(aq) + 4LiCoO2(S) + 4Li+
(aq) + 4Co(aq) →4Li2 C4 H4 O5(aq)
(33)
+ 8CoC4 H4 O5(aq) + 6H2 O + O2(g)
(34)
2+
(36)
They also investigated the addition of H2 O2 on promoting the con­
version of Co3+ to Co2+ to promote Co dissolution and improving Co
leaching efficiency through the following equations:
is
6C4 H6 O5(aq) +2LiCoO2(S)
+ H2 O2 →4LiC4 H5 O5(aq) +2Co(C4 H5 O5 )2(aq) +4H2 O + O2(g)
(37)
2+
6C4 H5 O−5(aq) + 2LiCoO2(S) + 2Li+
(aq) + 2Co(aq) + H2 O2 →2Li2 C4 H4 O5(aq)
+ 4CoC4 H4 O5(aq) + 4H2 O + O2(g)
(38)
They found that when LiCoO2 leached with only DL-malic acid, 37wt
% Co and 54wt% Li were leached. The addition of H2 O2 was essential as
it could significantly increase the leaching efficiency where 93wt% Co
and 99wt% Li were obtained. They observed that the best conditions for
cobalt and lithium leaching with DL-malic acid were 1.5 M DL-malic
acid, 2.0 vol% H2 O2 , 90 ◦ C for 40 min with a solid/liquid ratio of
20 g/L. At these conditions, 100wt% Li and more than 90wt% Co could
be leached. Zhou et al. [63] reported that leaching efficiency of 98.13wt
% for Li and 98.86wt% for Co could be reached by adopting ultrasoni­
cally enhanced leaching using 1.5 M DL-malic acid, 3vol% H2 O2 , and
80 ◦ C for 25 min with spray drying to regenerate LiCoO2 . Zhang et al.
[64] used grape seed as reductant. The catechin, epicatechin and epi­
gallocatechin gallate (EGCG) contained in grape seed were employed as
the efficient reductants during leaching. About 92% Co and 99% Li
could be leached with 0.6 g/g of grape seed, 1.5 M malic acid, 80 ◦ C
during 180 min, and slurry density 20 g/L. Leaching could also be done
with malic acid with glucose as reductant [65], and 98% of Co could be
precipitated using ammonium oxalate.
Meng et al. [66, 67] leached spent LiNi1/3 Co1/3 Mn1/3 O2 and LiCoO2
materials with malic acid and electrochemical cathode reduction. For
LiNi1/3 Co1/3 Mn1/3 O2 , the leaching efficiencies of Li, Ni, Co and Mn
reached to 100%, 99.87%, 99.58% and 99.82%, respectively, with
1.5 mol/L malic acid and a working voltage of 8 V at 300 r/min and
60 ◦ C for 30 min [66]. For LiCoO2 , the leaching efficiencies reached
about 90% for cobalt and nearly 94% for lithium using 1.25 mol/L of
malic acid and a working voltage of 8 V for 180 min at 70 ◦ C [67].
Fig. 9. Oxalate Leach of LiCoO2 Flowsheet [57].
9
J.C.-Y. Jung et al.
Journal of Energy Storage 35 (2021) 102217
6H2 Cit− (aq) +2LiCoO2(s)
+ H2 O2(aq) →2Li+ (aq) +6HCit2− (aq) +2Co2+ (aq) +4H2 O + O2(g)
(43)
6HCit2− (aq) +2LiCoO2(s)
+ H2 O2(aq) →2Li+ (aq) +6Cit3− (aq) +2Co2+ (aq) +4H2 O + O2(g)
(44)
Based on their investigation, the best conditions for the leaching of
spent LiCoO2 using citric acid were 1.25 M citric acid with 1.0 vol%
H2 O2 at 90 ◦ C for 30 min and a solid/liquid ratio of 20 g/L. At these
conditions, up to 100% Li and up to 96% Co were extracted. It should be
noted that citric acid with H2 O2 is not able to dissolve Co3 O4 thus not
able to fully extract the Co. Part of LiCoO2 could be transferred to Co3 O4
during the pre-treatment at high temperature for removing LiPF6 elec­
trolyte. Fig. 11 shows the proposed flowsheet.
2.8. Phosphoric acid as a hydrometallurgy treatment reagent
Zhuang et al. [71] reported using phosphoric acid (H3 PO4 ) and citric
acid mixture to leach spent NMC cathode material. With 0.2 M
Fig. 10. Proposed flowsheet for DL-malic Acid Leaching [60, 62, 63].
Fig. 10 shows the proposed flowsheet.
2.7. Citric acid as a hydrometallurgy treatment reagent
Citric acid has three carboxyls in one C6 H8 O7 ⋅H2 O molecule. 1 mole
of citric acid can release up to 3 mol H+ theoretically. The dissociation
reaction and the corresponding reaction constants of citric acid are as
follows:
H3 Cit→H2 Cit− + H+ K∂1 = 7.4 × 10− 4
(39)
H2 Cit− →HCi2− + H+ K∂2 = 1.7 × 10− 5
(40)
HCi2− →Cit3− + H+ K∂3 = 4.0 × 10− 7
(41)
Li et al. [68], Golmohammadzdeh et al. [69], and Musariri et al. [70]
used citirc acid with H2 O2 to leach spent LiCoO2 with the leaching re­
actions shown in the following:
6H3 Cit(aq) +2LiCoO2(s)
+ H2 O2(aq) →2Li+ (aq) +6H2 Cit− (aq) +2Co2+ (aq) +4H2 O + O2(g)
(42)
Fig. 11. Proposed flowsheet for Citric Acid Leaching [68-70].
10
J.C.-Y. Jung et al.
Journal of Energy Storage 35 (2021) 102217
phosphoric acid and 0.4 M citric acid with a solid to liquid (S/L) ratio of
20 g/L at 90 ◦ C for 30 min of retention time, leaching efficiency of 100%
for Li, 93.38% for Ni, 91.63% for Co, and 92.00% for Mn can be ach­
ieved, respectively.
Chen et al. [72] reported using H3 PO4 with H2 O2 to leach Li2 CoO2 .
By using 0.7 M H3 PO4 and 4 vol% H2 O2 , liquid to solid ratio of 20 mL
g − 1 at 40 ◦ C for 60 min of retention time, Co could be recovered as
cobalt phosphate Co3 (PO4 )2 precipitate while Li remaining in the
leachate with the following reactions:
Co2+ (aq) +Li+ (aq) +PO4 3−(aq) →1 / 3Co3 (PO4 )2(s) +1 / 3Li3 PO4(s)
(45)
3−
+
−
Li3 PO4(s) + 6H+
(aq) + 2PO4(aq) →3Li(aq) + 3H2 PO4(aq)
(46)
On the other hand, excess H3 PO4 could result in Co3 (PO4 )2 redissolving back into the leachate according to the following equation:
3−
2+
−
Co3 (PO4 )2(S) + 12H+
(aq) + 4PO4(aq) →3Co(aq) + 6H2 PO4(aq)
(47)
2.9. Ascorbic acid as a hydrometallurgy treatment reagent
Ascorbic acid is a nature occurring organic acid. Ascorbic acid be­
haves as a vinylogous carboxylic acid where the electrons in the double
bond, hydroxyl group lone pair, and the carbonyl double bond form a
conjugated system, which results in the hydroxyl group being more
acidic than typical hydroxyl groups. The pKa values of ascorbic acid are
pKa1 = 4.10 and pKa2 = 11.6, respectively. Ascorbic acid is known as a
reducing agent that can be oxidized by one electron to a radical state or
doubly oxidized to dehydroascorbic acid (C6 H6 O6 ).
Li et al. [73] leached the spent LiCoO2 with ascorbic acid. During
leaching, LiCoO2 was first dissolved and formed C6 H6 O6 Li2 , where Co3+
was reduced to Co2+ with ascorbic acid acting as a reducing agent and
ascorbic acid (C6 H8 O6 ) was oxidized to dehydroascorbic acid (C6 H6 O6 ).
Eq. (48) shows the leaching reaction, and Fig. 12 shows the proposed
flow sheet.
The optimum leaching conditions were found to be 1.25 M ascorbic
acid at 70 ◦ C for 20 min with solid/liquid ratio of 25 g/L, where 94.8%
Co and 98.5% Li were leached into the solution.
4C6 H8 O6 +2LiCoO2 →C6 H6 O6 + C6 H6 O6 Li2 +2C6 H6 O6 Co + 4H2 O
(48)
2.10. Benzenesulfonic acid with formic acid
Fu et al. [74] reported using 1.3 mol/L benzenesulfonic acid
(C6 H6 O3 S) and 1.5 mol/L formic acid (CH2 O2 ) mixture to leach Li2 CoO2
and achieved 97% leaching efficiency for Co and 99% for Li with a solid
to liquid (S/L) ratio of 30 g/L, and 40 min of retention time at 50 ◦ C. The
leached Co2+ was recovered from the leachate as pure cobalt benzene
sulfonic with 99% of recovery efficiency, and Li+ could be entirely
precipitated after Co removal with adding phosphoric acid to produce
lithium phosphate, Li3 PO4
Fig. 12. Proposed Flowsheet for Ascorbic Acid Leach [73].
FeS2 +7Fe2 (SO4 )3 +8H2 O→15FeSO4 +8H2 SO4
2S + 3O2 +2H2 O→2H2 SO4
2.11. Bioleaching
*microbial
(50)
*chemical
*microbial
4Fe2+ + O2 +4H+ →4Fe3+ +2H2 O
Mishra et al. [75], Xin et al. [76], and Zeng et al. [77] reported
bioleaching of spent LiCoO2 using chemolithotrophic and acidophilic
bacteria, and acidithiobacillus ferrooxidans (AF). AF utilized ferrous ion
(Fe2+) as the energy source to produce metabolites such as H2 SO4 and
ferric ions (Fe3+ ), which assisted leaching of spent LiCoO2 . The gener­
ated Fe3+ could induce a series of redox reactions, leading to the for­
mation of the strong reducing agent Fe2+, which then promoted the
reduction of Co3+ to Co2+ . The generated H2 SO4 enabled direct acid
dissolution of Co2+ . The following equations illustrate the bioleaching
process:
FeS2 +5O2 +4H+ →Fe3+ +2SO2−4 +2H2 O
*chemical
FeS2 +Fe2 (SO4 )3 →3FeSO4 +2S
(52)
*microbial
S + 3Fe2 (SO4 )3 + 4H2 O→4H2 SO4 + 6FeSO4
(51)
(53)
*chemical
(54)
2FeSO4 + 2LiCoO2 + 4H2 SO4 →Fe2 (SO4 )3 + 2CoSO4 + Li2 SO4
+ 4H2 O
*chemical
(55)
Mishra et al. [75] and Silverman et al. [78] conducted bioleaching
with AF and using 1% elemental sulfur and 3 g/L Fe2+ as the energy
source for AF. The result suggested that bioleaching of Co was faster
than lithium.
Zeng et al. [77] reported Cu-catalyzed bioleaching with AF and
found that the dissolution of Co was increased from 43.1% in 10 days
(49)
11
J.C.-Y. Jung et al.
Journal of Energy Storage 35 (2021) 102217
without Cu to 99.9% in 6 days with 0.75 g/L Cu. The result indicated
that the copper ions could enhance the oxidation of LiCoO2 . The
following equations illustrates the catalytic mechanisms:
2+
Cu +2LiCoO2 →CuCo2 O4 +2Li
+
*chemical
CuCo2 O4 +6Fe3+ →6Fe2+ +Cu2+ +2O2 +2Co2+
4Fe2+ + O2 +4H+ →4Fe3+ +2H2 O
Table 2
Comparison of hydrometallurgy treatments.
Hydrometallurgy
Treatment
(56)
*chemical
*microbial
Leaching
(58)
Fe2 O3 +6H →2Fe +3H2 O
(59)
FeS2 +14Fe3+ +8H2 O→15Fe2+ +2SO2−4 +16H+
(60)
FeS2 +6Fe3+ +3H2 O→7Fe2+ + S2 O2−3 +6H+
(61)
S2 O2−3 +8Fe3+ +5H2 O→8Fe2+ +2SO2−4 +10H+
(62)
2FeS2 +7O2 +2H2 O→2Fe2+ +4SO2−4 +4H+
(63)
Li2 CoMn3 O8 +2H2 SO4 →Li2 SO4 +CoSO4 +3MnO2 +2H2 O
(64)
4H+ +MnO2 +2Fe2+ →Mn2+ +2Fe3+ +2H2 O
(65)
2H+ +MnO2 + S2 O2−3 →Mn2+ +SO2−4 +S↓+H2 O
(66)
3+
2+
+
2LiCoO2 +3H2 SO4 +2Fe +2H →Li2 SO4 +2CoSO4 +4H2 O + 2Fe
3+
Advantage
Disadvantage
1
HCl
Chemical
inexpensive
2
HNO3
High extraction
rate on Co and Li
3
H2 SO4
chemical
inexpensive
4
H3 PO4
Low acid
consumption,
5
Organic acid
6
Bioleaching
Environmental
friendlier
Environmental
friendlier
Low energy
consumption, low
cost
Equipment
corrosion, Cl
contamination
Dissolve Al,
oxidize Mn and
Co, NOx in
discharge
sulfate ion has
solubility
limitation
Phosphate has
very limited
solubility
Lower extraction
rate
Low kinetic, low
extraction rate
pH adjustment
difficult to
control, metals
often coprecipitated
Process very
complicated,
multiple
extraction stages,
high cost of
solvents,
generated
wastewater and
emission, Toxic
solvents needed
to be waste
treated
(57)
The work from Mishra et al. [75], Xin et al. [76], and Zeng et al. [77]
indicated that it was possible to recover metal from spent lithium-ion
cathode material by acidophilic bacteria. Huang et al. [79] reported
using
potential
sulfur-oxidizing
bacteria
with
a
bio-electro-hydrometallurgical platform to recover Li, Mn, and Co from
spent lithium ion batteries. The bioleaching process and selective
adsorption by PC-88A/TOA-modified granular activated carbon are
both incorporated into an electrokinetics approach to achieve maximum
recoveries of 91.45%, 93.64% and 87.92% for Co, Li, and Mn respec­
tively. The proposed chemical reactions are as follows:
+
Chemical
used
(68)
Mn2+ +2OH− →Mn(OH)2(S)
(69)
2Mn(OH)2 + O2 →2MnO(OH)2(s)
(70)
NaOH, LiOH,
Na2 CO3 ,
Li2 Co3
Solvent extraction
D2EHPA,
Cyanex 272,
Acorga
M5640, PC88A,
TODGA,
P66614-Cl,
DES
Able to extract
individual metal
ions, high
separation
efficiency, low
energy
consumption
ery. Various chemicals including H2 SO4 , citric acid (C6 H8 O7 ), Na2 S2 O8 ,
oxalic acid (C2 H2 O4 ), acetic acid (CH3 COOH), HCl, phosphoric acid
(H3 PO4 ), and H2 O2 have been reported to be employed for leaching.
Metal recovery is conducted through precipitation, solvent extraction
(SX), or ion-exchange [89].
Yang et al. [90] used mechanochemical activation with EDTA-2Nato
recover lithium using sodium hydroxide (NaOH) and H3 PO4 , achieved a
94.3% Li leaching efficiency and an overall of 82.6% Li recovery. He
et al. [91] demonstrated that leaching with (NH4 )2 S2 O8 could selec­
tively leach 97.5% Li. Yadav et al. [92] reported that methanesulfonic
acid with H2 O2 could have a 94% Li leaching efficiency. Zhang et al.
[93] demonstrated that sodium persulfate (Na2 S2 O8 ) could selectively
leach 99% Li within 20 min; and with sodium carbonate (Na2 CO3 ), 95%
of Li could be recovered as lithium carbonate (Li2 CO3 ). Li et al. [94]
used oxalic acid to achieve 98% Li leaching efficiency. Yang et al. [95]
showed that leaching with acetic acid and H2 O2 , and precipitating with
Na2 CO3 , over 95% of Li could be leached and recovered. Furthermore,
Jing et al. [96] showed that with H2 O2 , up to 95.4% of Li could be
leached. Li et al. [97] used citric acid to leach and Na2 CO3 to recover Li
and achieved 99.35% of leaching efficiency and 95% recovery.
On the other hand, H2 SO4 and HCl are widely reported to leach Li
from spent LiFePO4 . Tao et al. [98], Zheng et al. [99], and Tedjar et al.
[100] used H2 SO4 to leach above 97% of Li within 4 h. Li et al. [101], Cai
et al. [102], and Schurmans et al. [103] added H2 O2 as an oxidant into
H2 SO4 leaching, the leaching time could be reduced.
Song et al. [104] used HCl to leach and using SX to recover up to 90%
of Li. Wang et al. [105] illustrated that leaching with HCl and precipi­
tating with Na3 PO4 could recover up to 96% of Li. Huang et al. [106]
combined flotation with HCl leaching of Li. Li et al. [107] used elec­
trolysis cell with anionic membrane to delithiate and oxidize LiFePO4 to
FePO4 on the anode compartment. Li+ was then join with OH− ions were
produced from hydrogen evolution and passed through the anionic
(67)
2H+ +4LiCoO2 +4H2 SO4 + S2 O2−3 →2Li2 SO4 +4CoSO4 +3H2 O
Precipitation
Hydrometallurgical recycling involves dissolving the valuable cath­
ode materials in acids and separating the constituent metals using
chemical precipitation or solvent extraction. This approach can recover
the valuable metals such as Ni, Co, Mn, Li into individual chemicals,
chemical precursor or new cathode materials. As the trend is to decrease
valuable metal content like Co in cathode material, it is important to
ensure the simple processes, low reagent consumption rate, and high
metal recovery can be achieved in order to keep hydrometallurgical
process profitable. Table 2 shows the comparison of various leaching
treatments and metal recover processes.
2.12. Lithium iron phosphate battery recycle
Lithium iron phosphate (LiFePO4 or LFP) batteries are used in energy
storage and electric vehicles like Tesla Model 3 (China version). Pro­
cesses to recycle of spent LFP can be categorized to direct recycling and
hydrometallurgical recycling.
Direct recycling regenerates LiFePO4 through replenish lithium into
spent LiFePO4 and reshape material structure using hydrothermal
method [80-88]. Table 3 summarizes the operation conditions from
literatures.
LiFePO4 can also be recovered through hydrometallurgical recycling.
Hydrometallurgical recycling is consisted of leaching and metal recov­
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J.C.-Y. Jung et al.
Journal of Energy Storage 35 (2021) 102217
Table 3
Process summary to direct regeneration of LiFePO4 .
No
Process
Additives
Heat treated time
(h)
Temp (
◦
C)
Li
Source
1
Hydrothermal
LiOH, L-ascorbic acid, Dodecyl benzene sulphonic acid
sodium (SDBS)
6
160
LiOH
2
Thermal ball milling
Sucrose, Li2 Co3
2
800/650
Li2 Co3
3
Ball milling
Li2 Co3
N/A
Heat treatment
4
Heat treatment
5
Heat treatment
6
Heat treatment
7
Heat treatment
8
Leaching + reprecipitate
9
Annealing
Leaching
Heat treatment
Ball milling
Heating Inner
Atmosphere
Reference
80
H2 / Ar
81
Li2 Co3
700
Glucose, Li2 Co3
2
900
LiFePO4
8
700
Li2 Co3
1
650
1
650
H3 PO4
9
85
10
700
8
700
Li Leaching
Efficiency (%)
Metal Recovery (Precipitation, SX, Ion exchange)
Chemical
Temp (
Yield
◦
C)
(%)
Reference
94.3
5 M NaOH
82.6
90
97.5
Na2 S to form NaFeS2
85
92
Li2 Co3
Li2 Co3
82
N2
Li2 Co3
N/A
Li2 Co3
6 M HCl, NH4 OH
LiOH, Sucrose
83
LiFePO4
84
H2 / Ar
85
H2 / Ar
86
87
N2
88
LiOH
Heat treatment
H2 / Ar
Table 4
Hydrometallurgy Process to leach and recover Li from spent LiFePO4 .
No
Leaching
Chemical
Time
(h)
1
0.6 M H3 PO4
20
30
2
Mechanochemical activation with
EDTA-2Na
(NH4 )2 S2 O8
3
Temp (
◦
C)
Pulp Density
1
1.5
25
40 g/L
94
4
Methanesulfonic acid, ptoluenesulfonic acid H2 O2
Na2 S2 O8
1/3
25
300 g/L
5
6
0.3 M Oxalic acid
0.8 M Acetic acid, 6vol% H2 O2
1
1/2
80
50
60 g/L
120 g/L
2.8 M H2 O2
4
25
200 g/L
95.4
8
Citric acid, H2 O2
2
9
0.28 M H2 SO4
20 g LFP / 20 g
acid
100 g/L
97
7
10
11
12
13
14
15
4
85
2.5 M H2 SO4
4
60
0.3 M H2 SO4 , H2 O2
2
2 M H2 SO4
4 M H2 SO4 , 2vol% H2 O2
H2 SO4 , O2 / H2 O2
96
99
Na2 CO3
95
98
95.1
Na2 CO3
95
84.8
99.35
Na2 CO3
95
85.4
97
98.46
Na2 PO4
84.2
98
80
60
80–120
100 g/L
92
HCl
16
4 M HCl
17
6.5 M HCl, 15vol% H2 O2
60
200 g/L
92.2
94
95
96
99
100
Na3 PO4
65
92.5
101
Na3 PO4
60
90
102
SX: 40% D2EHPA with
Kerosene
Strip with HCl
35
90
104
Precipitate with
Na2 CO3
80
Na3 PO4
90
Na2 CO3
103
35
Na3 PO4
2
93
Na2 CO3
H3 PO4
60
2
91
Na2 CO3
96
105
80.9
106
Cardarelli et al. [108] used a freezing method to harden the polymer
electrolyte and comminute the cooled and hardened material before the
comminuted material subjected to incineration, leaching and precipi­
tation to recover lithium and vanadium.
membrane to form LiOH. Li+ could then be recovered through adding
Na2 CO3 to form Li2 CO3 .
Table 4 shows the comparison of the leach and metal recover oper­
ation conditions of the hydrometallurgy process.
Due to the low cost of iron phosphate, hydrometallurgical recycling
to recover individual materials like Fe, PO3−
4 and Li is not economic
feasible. Direct recycling to regenerate LiFePO4 or direct generate
LiFePO4 during hydrometallurgical recycling should be the focus.
3. Brief description of pyrometallurgical recycling process and
recycling processes in the market
3.1. Pyrometallurgical recycling process
2.13. Lithium polymer battery recycle
Currently, there are several pyrometallurgy or smelting facilities that
commercially recycling Lithium-ion batteries. The pyrometallurgical
process often runs at near 1500 ◦ C to recover cobalt, nickel, and copper
but not lithium, aluminum, or any organic compounds. Fig. 13 shows a
Lithium metal polymer batteries consist an ultra-thin lithium metal
foil anode, a solid copolymer electrolyte containing a lithium salt, and a
lithium vanadium oxide cathode. To recycle lithium polymer battery,
13
J.C.-Y. Jung et al.
Journal of Energy Storage 35 (2021) 102217
Fig. 13. Schematic of pyrometallurgical recycling of spent lithium ion battery [109].
schematic of pyrometallurgy recycling process. [109]
Pyrometallurgical recycling process is capital intensive, in part
because of the need to treat the emission of toxic fluorine compounds
released during the smelting. After the pyrometallurgy process, valuable
metals are reduced and then recovered in the form of alloys. For
example, Umicore develops the pyrometallurgical and hydrometallur­
gical processes to recycle Ni, Co, and Li from spent lithium-ion batteries
[110]. Georgi-Maschler et al. [111] used a reductive smelting process to
recover valuable metals from the spent lithium-ion batteries. The Fe, Co,
Ni, and Mn in the batteries were converted to alloys, and Li during the
reductive smelting reported to slag which could be recovered with
further leaching using H2 SO4 . Trager et al. [112] used vacuum evapo­
ration and selective carrier gas evaporation at temperatures above
1400 ◦ C to evaporate Li from the spent lithium-ion batteries. Liang et al.
[113] reported a high-temperature pyrolysis to regenerate spent
LiFePO4 cathode materials with smooth material surface and small
particle sizes. Tang et al. [114] reported a vacuum pyrolysis approach to
recover Li and Co from the spent LiCoO2 . Wang et al. [115] roasted
Li2 CoO2 with NaHSO4 ⋅H2 O to selectively separate Li and Co. Wang et al.
[116] investigated catalytic carbothermic reduction by heating the
mixture of LiCoO2 , graphite, and NaOH at 520 ◦ C for 180 min. Water
leach of the heated mixture showed that 93% Li could be extracted while
Co retained in the solid.
3.2. AkkuSer
AkkuSer, a Finnish company, develops a Dry-Technology method to
recycle high-grade cobalt Li-ion batteries. The Dry-Technology method
is a mechanical process and does not require any preprocessing steps for
discharging the Lithium-Ion batteries. The mechanical process is based
on two-stage crushing line followed by magnetic and mechanical sepa­
ration unit. The outputs of the process are metal concentrates which are
delivered as the raw material to metal refineries. The process uses no
water, chemicals or heating thus does not produce any related emis­
sions. [117]
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Journal of Energy Storage 35 (2021) 102217
3.3. American manganese
3.7. Lithion recycling
American Manganese Inc., a company headquarter in British
Columbia Canada, with its research partner Kemetco Research Inc.,
develops RecycLiCo™ process, a closed-loop, hydrometallurgical pro­
cess with SO2 reductive leaching system and electrochemical process to
recycle cathode material scraps from cathode manufacturers and spent
cathode materials. The process achieves near 100% recovery and battery
grade purity of materials such as lithium, cobalt, nickel, manganese, and
aluminum from varies cathode chemistries including NCA, NMC, LCO,
and LMO [118].
Lithion Recycling, a company headquarter in Quebec Canada, de­
velops a hydrometallurgical recycling process solution that recovers
95% of all components from lithium-ion batteries with battery chemis­
tries from LCO, NMC, LMO, NCA, and LFP and regenerates materials
with high purity [123].
3.8. LithoRec process - Duesenfeld
Duesenfeld GmbH, a company in Weendeburg Germany develops a
patented the mechanical, thermodynamic, and hydrometallurgical
process which adopts LithoRec process, as shown in Fig. 15. LithoRec
process first deeply discharges the spent lithium-ion batteries and then
shreds the batteries under an inert atmosphere. Second, battery elec­
trolyte that is consisted of a mixture of linear and cyclic carbonates, and
a conducting salt is extracted by vacuum distillation, sub- and super­
critical CO2 extraction, dimethyl carbonate (DMC) liquid extraction, or a
thermal drying step. Third, subsequently iron parts are removed via
magnetic separation and transferred to scrap metal recycling. Fourth,
the residual non-magnetic material is fed to a zig-zag air classifier,
where the shredded material is further separated into two fractions
containing the current collectors and active materials and the other
fraction consisting of the separator and plastic foils. Fifth, the active
material, graphite, and the current collector are separated and collected
by heating up to 400 – 600 ◦ C to remove the binder and using air jet
sieves. Sixth, the active material is fed to a hydrometallurgical step
where the active material is dissolved in an acidic mixture and lithium
can be leached out [124, 125].
3.4. Brunpt recycling
Brunpt Recycling (Brunpt) is a subsidiary of Contemporary Amperex
Technology Co. Ltd (CATL), one of the biggest lithium-ion battery
manufacturers in China. Brunpt recycles spent cathode material through
a hydrometallurgical process with solvent extraction, which can achieve
a recovery rate of nickel, cobalt, and manganese up to 99.3% [119].
3.5. Direct recycling and onto direct recycling
Direct recycling, as shown in Fig. 14(1), separates different battery
active materials through physical processes like gravity separation and
flotation without causing chemical changes to recover cathode materials
that are reusable. The reusable cathode materials are replenished with
lithium through a solid-state method topping up with stoichiometric
addition of lithium. Also, the process resets transition metal oxidation
numbers to the original spinel structures. However, contamination like
polyvinyl difluoride polymer that binds cathode-carbon mixtures and
transition metal dissolution have limited the development [120].
OnTo Technology LLC, a company in Oregon USA, develops a direct
recycling process with CO2 deactivation and hydrothermal process, as
shown in Fig. 14(2) to directly reutilise the parts taken from the used
batteries to make new lithium-ion batteries [120, 121].
3.9. Retriev technologies
Retriev Technologies, a company in British Columbia Canada, de­
velops a process involving disassemble and dismantle spent lithium-ion
battery pack followed by feeding the separated spent lithium-ion battery
cells and smaller packs (i.e. laptop, power tool, and cell phone) by
conveyor to an automated crusher. The crusher, which operates under a
liquid solution to prevent fugitive emissions and to reduce the reactivity
of processed batteries, produces three types of materials, which are
metal solids, metal-enriched liquid, and plastic fluff [126, 127].
Pending on the chemistry of spent lithium-ion batteries, the metal
solids may contain various amounts of Cu, Al, and Co, which can all be
used as raw materials in new products. The metal-enriched liquid is
solidified using filtering technology and sent off-site for further metal
purification.
3.6. Li-Cycle
Li-Cycle is a startup from Canada that uses a combination of me­
chanical size reduction and hydro-metallurgical recovery techniques to
recycle lithium-ion batteries. Li-Cycle process breaks down the batteries
to inert battery materials and the mixed copper/aluminum metals. The
inert battery materials, which are consisted of a mix of cathode and
anode battery materials, including lithium, nickel and cobalt, as well as
graphite, copper and aluminum, are further treated with a hydromet­
allurgical process to produce nickel sulfate, cobalt sulfate, manganese
carbonate, and lithium carbonate [122].
Fig. 14. (1) Direct recycling, (2) OnTo direct recycling process [120].
15
J.C.-Y. Jung et al.
Journal of Energy Storage 35 (2021) 102217
Fig. 15. LithoRec process [124,125].
Fig. 16. Sumitomo recycling process [128].
3.10. Sumitomo
refined using a hydrometallurgical process to recycle the nickel and
cobalt for use as a battery material and the copper for electrolytic
copper.
Sumitomo Metal Mining Co. Ltd. (SMM), a company headquartered
in Tokyo, develops a process to recover and recycle Cu and Ni from the
spent lithium-ion batteries by smelting and refining the metals, as shown
in Fig. 16 [128].
The process that SMM developed selectively recovers nickel, cobalt
and copper as an alloy by using a pyrometallurgical refining process
independent of the existing process to separate most of the impurities
from the spent lithium-ion batteries. Then the alloy is leached and
3.11. Umicore
Umicore, a company headquartered in Brussels Belgium, develops a
unique pyro-metallurgical treatment and a hydro-metallurgical process,
as shown in Fig. 17 [129].
The pyro-metallurgical phase converts spent lithium-ion batteries
16
J.C.-Y. Jung et al.
Journal of Energy Storage 35 (2021) 102217
Fig. 17. Umicore battery recycling process [129].
Table 5
Current recycling companies in the market.
No
Company
Process
Pre-treatment
Mechanical
Pyrometallurgy
Hydrometallurgy
Recycled Battery
Element Form
Energy
Consumption
Status@2020
1
AkkuSer
Sorting
Size reduction,
magnetic separation
N/A
N/A
N/A
Co, Cu, Fe
Low
Pilot Plant
2
American
Manganese
Sorting, active
material / Current
collector separation
N/A
H2 SO4 , SO2
reductive leach
LiOH, Ni(OH)2 ,
Co(OH)2 , Mn(OH)2 ,
Al
Low
Pilot Plant
3
Brunpt
Recycling
Discharge,
Dismantling
N/A
N/A
H2 SO4 , H2 O2
reductive leach,
Solvent extraction
Ni, Co, Mn, Al
Medium
Commercial
Plant
4
Duesenfeld
Discharge,
Disassembly
Discharge
Crushing
Calcination
Li2 CO3 Metal Oxide
High
Pilot Plant
Size reduction
Magnetic separation
Flotation
N/A
Undisclosed
Leaching reagent
H2 SO4 , H2 O2 ,
reductive leach
Solvent extraction
5
Li-Cycle
NiSO4 , COSO4 ,
MnCO3 , Li2 CO3
Medium
Commercial
Plant
6
Lithion
Recycling
OnTo
Technology
N/A
N/A
Co, Ni, Mn, Al
Medium
Pilot Plant
Discharge,
Dismantling
Shredding,
Supercritical CO2
electrolyte removal
Brief Heating
Undisclosed
Leaching reagent
Hydrothermal
Cathode Materials
Medium
Pilot Plant
Dismantling
N/A
Al, Cu, Li Ni, Co
Low
Sorting, Dismantling
Wet crushing,
screening, flotation
Heat Treatment
N/A
9
Retriev
Technologies
Sumitomo
Smelting
Ni, Co, Cu
High
10
Umicore
Dismantling
N/A
Smelting
Electrowinning
H2 SO4 leach
Commercial
Plant
Commercial
Plant
Ni(OH)2 , LiMeO2
High
7
8
Leaching, Solvent
Extraction
Co, Ni refining
into 3 fractions. The first is an alloy fraction that contains valuable
metals like Co, Ni, and Cu designed for the downstream hydrometallurgical process. The second is a slag fraction which can be used
in the construction industry or further processed for metal recovery. The
third fraction is clean air released from the stack after it has been treated
by the unique gas cleaning process. The alloy fraction is fed to the
subsequent hydro-metallurgical process, where the alloy is further
refined to convert the metals into active cathode materials for new
lithium-ion batteries. [130]
The following Table 5 compares the available recycling technologies
in the market.
Commercial
Plant
4. Challenges in recycling lithium-ion battery cathode materials
4.1. Economy challenges
Currently, the main options for the treatment of spent lithium-ion
batteries are landfilling, reuse, and recycling with pyrometallurgical
process and hydrometallurgical processes or direct recycling. Landfilling
may cause pollution as metal like Co, Li, Fe, Mn, and Cu may slowly
leaching into soil, groundwater, or surface water. Reusing the retired
electric vehicle batteries is of great interest as these batteries usually
holding 70 ~ 80% of residual energy capacities and can support proper
application for long-term [131]. However, to reuse, the retired batteries
need to be tested, recategorized, reconfigured, and fitted with a suitable
battery-management system (BMS). The cost for these exercises could be
17
J.C.-Y. Jung et al.
Journal of Energy Storage 35 (2021) 102217
higher than new batteries. Recycling with pyrometallurgical process
recovers the valuable metals like Ni, Co, Mn, and Cu and let go of Li,
electrolyte, and anode material. Due to the high energy consumption,
the economy of pyrometallurgical process depends on the metal prices
especially Co. As current trend of research is to reduce the quantity of Co
in lithium ion battery, the economic challenges is greater down the road
[132].
Recycling with hydrometallurgical processes are largely price driven
as technology is not a critical differentiating factor. Despite the choice of
leaching agent or metal recovery method, the hydrometallurgical pro­
cesses offer the same level of final products. Therefore, the key differ­
entiating factor becomes price. Although the cost to process spent
cathode material is lower than the cost to process virgin raw material
when fabricating new cathode material, recycling with hydrometallur­
gical process is still not economically feasible after including the cost of
transportation, dismantle, and disassemble [133]. Furthermore, current
cost to product lithium from brine solution is around USD $1800 per
tonne and from hard rock is USD $5000 per tonne [134]. The low cost of
lithium production creates a barrier for recycling lithium from spent
lithium-ion batteries. Lithium-ion batteries contain only a small fraction
of lithium as a percent of weight. The average lithium cost associated
with Lithium-ion battery production is less than 3% of the production
cost. As such, although lithium is 100% recyclable through recycling
spent cathode material, electrolyte, and LTO anode, recycling lithium
will not be the focus until the volume of the spent lithium-ion batteries
grows exponentially.
Another challenge hindering the industry is the long-term nature of
financial investments required by market participants to develop spe­
cialised waste disposal services. As the market is still unexplored, spe­
cialised processes and dedicated small scale recycling plants closer to
vehicle manufacturers or lithium-ion battery recycling facilities are
likely to be the trend in the near future. These specialised, customized
processes increase the required financial investments and render the
overall profitability of investments unknown, thereby create ambiguity
and uncertainty about making such commitments.
to be extracted without contacting water to avoid the release of poisonous
hydrofluoric acid (HF) by the following reaction:
LiPF6 + H2 O→HF + LiOH + PF5
(71)
Furthermore, if electrolyte is not extracted and high heat is gener­
ated during battery disassemble due to partial internal short circuits,
water moisture could turn to steam and react with LiPF6 to generate
highly corrosive HF and phosphorus oxyfluoride (POF3 ) by the following
reaction:
LiPF6 + H2 O→POF3 +2HF + LiF
(72)
In addition, during decomposing, if internal short circuits and ther­
mal runaway happen, it will cause explosion. To avoid thermal runaway,
the safest approach is to have the lowest amount of spent li-ion batteries
on site as possible. However, this is contradictory to the requirement to
secure stable feedstock for processing purposes. The development of safe
storage is further complicated by the various form factors and not
knowing if the batteries are damaged or not. As a result, strict protocols
must be implemented regarding the pallet/container spacing, total
storage density and application of appropriate fire suppression systems
within any lithium-ion battery storage space in order to mitigate the risk
associated with thermal runaway and fire [138].
These concerns and requirements increase the upfront capital in­
vestment, operation cost, and risk for spent lithium-ion battery recy­
cling. As such, it is important to develop a simple, environmentally
acceptable, and economic recycling process to recycle the valuable
metals from lithium-ion batteries.
5. Conclusion
Unlike oil, where the volatile price fluctuations will lead to increase
in only the running costs, potential price fluctuations of lithium and
metals would impact the total purchase price of the Lithium-ion battery
powered electric vehicles. It is believed that the current trend of electric
vehicle development, demands from consumer electronics, geo-political
relationships, and environmental regulations will crunch the supply and
raise the price of lithium and other important metals. The concentra­
tions of lithium and metals inside spent lithium-ion batteries exceed the
concentrations in natural ores, making spent lithium-ion batteries
similar to upgraded, highly enriched ore and offer an alternative supply
source for battery material. Currently, there is no simple route to recy­
cling of Lithium-ion batteries. The commercialized recycle process
largely based on pyrometallurgy or hydrometallurgy with solvent
extraction, both have toxic waste emission.
The hydrometallurgy recycle processes reviewed in this paper,
including hydrochloric acid (HCl), nitric acid (HNO3 ), sulfuric acid
(H2 SO4 ), oxalate (H2 C2 O2 ), DL-malic acid (C4 H5 O6 ), citric acid
(C6 H8 O7 ), ascorbic acid (C6 H8 O6 ), phosphoric acid (H3 PO4 ) or acid­
ithiobacillus ferrooxidans, still require further investigations. These re­
ported hydrometallurgical processes still need to be refined to determine
key parameters in terms of reagent consumption, water balance, byproducts, discharge, and product yield to establish the overall flow­
sheets and mass balance for process commercialization and economics.
For example, leaching with HCl will likely generate chlorine (Cl2 ) and
leaching with HNO3 will likely generate NOX . Furthermore, as Ni, Co,
and Mn are the current recycle focus, solvent extraction is the main
practice for the hydrometallurgical recycling companies in operation.
Solvent extraction process has a bigger environment impact as it does
not recycle lithium and has wastewater to handle.
The methods to capture and deal with these by-products would have
huge impacts on the economic of spent lithium-ion battery recycling.
Finding economical and environmentally friendly recycling pro­
cesses is imminent. The following research directions can be proposed to
achieve the goals:
4.2. Feedstock supply and logistics
The various lithium ion battery chemistries, (i.e. LFP, NCA, NMC,
LCO, LMO etc.), scatter size and format, complicated distribution
channels challenge recycling plant to collect a stable feedstock. A more
flexible and universal recycling process is required for the recovery of
different types of spent lithium-ion batteries, as well as a process
including the recycle of electrolyte and anode materials [135].
Furthermore, the spent lithium-ion batteries, especially damaged/
defective batteries can possibly undergo thermal runaway, typically
resulting from internal shorting, leading to fire or explosion. Govern­
ments around the world are modifying the transportation regulations
year to year as they recognize the potential hazardous of the spent
lithium-ion batteries.
Currently in North America, spent lithium-ion battery are classified
as Class 9, miscellaneous hazardous materials, under United States
regulations (40 CFR 173.21(c)) [136]. The transportation of spent
lithium-ion battery needs to be in specification packaging (UN Pack­
aging), which increase the cost, the effort is needed to achieve regula­
tory compliance, and the complexity of transportation spent lithium-ion
batteries to the recycling plant.
4.3. Safety and storage
Lithium-ion batteries when over-charging, over-discharging, or heat­
ed might cause chemical such as electrolyte leakages or explosions. [137].
To ensure the safety of spent lithium-ion battery recycling process, spent
batteries first need to be deep-discharged to avoid violent reaction from
the charged electrodes releasing the stored energy when exposed to air.
Secondly, battery electrolyte, lithium hexafluorophosphate (LiPF6 ), needs
18
Journal of Energy Storage 35 (2021) 102217
J.C.-Y. Jung et al.
1 Establishing theoretical modeling for fundamental understanding of
the recycling systems for material downstream selection and effi­
ciency improvement.
2 Researching pre-treatment to recover fluoride contained electrolyte
and separator to enable the recycling process building with inex­
pensive materials.
3 Understanding and control impurity that will be entering the recycle
process in order to produce high purity and high value products.
4 Finding more economical recycling processes and developing prod­
ucts from all by-products to reduce the overall recycling process.
5 Developing closed loop recycle process to reuse reagent or regen­
erate reagent to minimize reagent consumption and emission and
avoid the production of toxic gasses and waste liquids.
Lithium ion Batteries and its Characterization by Gas Chromatography with
Chemical Ionization, J. Power Sources 352 (2017) 56–63.
[16] Y. Liu, D. Mu, R. Li, Q. Ma, R. Zheng, C. Dai, Purification and Characterization of
Reclaimed Electrolytes from Spent Lithium-Ion Batteries, J. Phys. Chem. C 121
(2017) 4181–4187.
[17] Mitch Jacoby, It’s time to get serious about recycling lithium-ion batteries, Chem.
Eng. News 97 (28) (2019). https://cen.acs.org/materials/energy-storage/time
-serious-recycling-lithium/97/i28.
[18] A.W. Golubkov, D. Fuchs, J. Wagner, H. Wiltsche, C. Stangl, G. Fauler, G. Voitic,
A. Thaler, V. Hacker, Thermal-runaway Experiments on Consumer Li-ion
Batteries with Metal-Oxide and Olivin-type Cathodes, RSC Adv. 4 (2014) 3633.
[19] X. Zheng, Z. Zhu, X. Lin, Y. Zhang, Y. He, H. Cao, Z. Sun, A Mini-Review on Metal
Recycling from Spent Lithium Ion Batteries, Engineering 4 (2018) 351–379.
[20] P. Zhang, T. Yokoyama, O. Itabashi, T. Suzuki, K. Inoue, Hydrometallurgical
process for recovery of metal values from spent lithium-ion secondary batteries,
Hydrometallurgy 47 (1998) 259–271.
[21] M. Contestabile, S. Panero, B. Scrosati, A laboratory-scale lithium-ion battery
recycling process, J. Power Sources 92 (2001) 65–69.
[22] Z. Takacova, T. Havlik, F. Kukurugya, D. Orac, Cobalt and lithium recovery from
active mass of spent li-ion batteries: theoretical and experimental approach,
Hydrometallurgy 163 (2016) 9–17.
[23] R. Wang, Y.C. Lin, S.H. Wu, A novel recovery process of metal values from the
cathode active materials of the lithium-ion secondary batteries, Hydrometallurgy
99 (2009) 194–201.
[24] Y. Yang, S. Lei, S. Song, W. Sun, L. Wang, Stepwise recycling of valuable metals
from Ni-rich cathode material of spent lithium-ion batteries, Waste Manage.
(Oxford) 102 (October) (2019) 131–138.
[25] Castillo S., Ansart F., Labberty R., and Portal J., Advances of recovering of spent
lithium battery compounds, J. Power Sources 112: 247–254.
[26] C.K. Lee, K.I. Rhee, Preparation of LiCoO2 from spent lithium-ion batteries,
J. Power Sources 109 (2002) 17–21.
[27] C.K. Lee, K.I. Rhee, Reductive leaching of cathodic active materials from lithium
ion battery wastes, Hydrometallurgy 68 (2003) 5–10.
[28] L. Li, R. Chen, F. Sun, F. Wu, J. Liu, Preparation of LiCoO2 films from spent
lithium-ion batteries by a combined recycling process, Hydrometallurgy 108
(2011) 220–225.
[29] C. Vu, K.N. Han, F. Lawson, Leaching behaviour of cobaltous and cobalto-cobaltic
oxides in ammonia and in acid solutions, Hydrometallurgy 6 (1980) 75–87.
[30] L. Sun, K. Qiu, Vacuum pyrolysis and hydrometallurgical process for the recovery
of valuable metals from spent lithium-ion batteries, J. Hazard Mater. 194 (2011)
378–384.
[31] D.A. Ferreira, L.M. Prados, D. Majuste, Mansur MB, Hydrometallurgical
separation of aluminum, cobalt, copper, and lithium from spent li-ion batteries,
J. Power Sources 187 (2009) 238–246.
[32] A.A. Nayl, R.A. Elkhashab, S.M. Badawy, M.A. El-Khateeb, Acid leaching of mixed
spent li-ion batteries, Arabian J. Chem. 10 (2017) S3632–S3639.
[33] G. Dorella, M.B. Mansur, A study of the separation of cobalt from spent li-ion
battery residues, J. Power Sources 170 (2007) 210–215.
[34] L. Chen, X. Tang, Y. Zhang, L. Li, Z. Zhen, Y. Zhang, Process for the recovery of
cobalt oxalate from lithium ion batteries, Hydrometallurgy 108 (2011) 80–86.
[35] J. Kang, G. Senanayake, J.S. Sohn, Shin SM, Recovery of cobalt sulfate from spent
lithium ion batteries by reductive leaching and solvent extraction with Cyanex
272, Hydrometallurgy 100 (2010) 168–171.
[36] S.M. Shin, N.H. Kim, J.S. Sohn, D.H. Yang, Y.H. Kim, Development of a metal
recovery process from li-ion battery wastes, Hydrometallurgy 79 (2005) 172–181.
[37] S. Zhu, W. He, G. Li, X. Zhou, X. Zhang, J. Huang, Recovery of Co and Li from
spent lithium-ion batteries by combination method of acid leaching and chemical
precipitation, Trans. Nonferrous Metal Soc. China 22 (2012) 2274–2281.
[38] B. Swain, J. Jeong, J. Lee, G.H. Lee, J. Sohn, Hydrometallurgical process for
recovery of cobalt from waste cathodic active material generated during
manufacturing of lithium ion batteries, J. Power Sources 167 (2007) 536–544.
[39] J. Nan, D. Han, M. Yang, M. Cui, X. Hou, Recovery of metal values from a mixture
of spent lithium-ion batteries and nickel-metal hydride batteries,
Hydrometallurgy 84 (2006) 75–80.
[40] W.S. Chen, H.J. Ho, Recovery of valuable metals from lithium-ion batteries NMC
cathode waste materials by hydrometallurgical methods, Metals (Basel) (May)
(2018).
[41] X. Yang, P. Dong, T. Hao, Y. Zhang, Q. Meng, Q. Li, S. Zhou, A combined method
of leaching and co-precipitation for recycling spent LiNi0.6Mn0.2O2 cathode
materials: process optimization and performance aspects, J. Minerals Metals
Mater. Soc. (TMS) 72 (11) (2020) 3843–3852.
[42] J. Wang, M. Chen, H. Chen, T. Luo, Z. Xu, leaching study of spent li-ion batteries,
Procedia Environ. Sci. 16 (2012) 443–450.
[43] N. Vieceli, C. Nogueira, C. Guimaraes, M. Pereira, F. Durao, F. Margarido,
Hydrometallurgical recycling of lithium-ion batteries by reductive leaching with
sodium metabisulphite, Waste Manage. (Oxford) 71 (2018) 350–361.
[44] Long B.Q., Diao J., and Ceng F.Y., Method of leaching spent lithium cathode
material - lithium cobalt dioxide, CN103757394A (2014).
[45] Chow N., Jung, J., Nacu A., Warkentin, D., Processing of cobaltous sulphate/
dithionate liquors derived from cobalt resource, United State Patent 10246343
B2, April (2019).
[46] G. Granata, E. Moscardini, F. Pagnanelli, F. Trabucco, L. Toro, Product recovery
from li-ion battery waste coming from an industrial pre-treatment plant: lab scale
tests and process simulations, J. Power Sources 206 (2012) 393–401.
Recycling is expected to be an important factor for consideration in
effective material supply for battery production to hedge against the
uncertain and potential price fluctuations and supply shortage, as well
as the usage sustainability of lithium-ion batteries.
Declaration of Competing Interest
The authors declare that they have no known competing financial
interests or personal relationships that could have appeared to influence
the work reported in this paper.
Acknowledgement
The authors gratefully acknowledge the financial support from
Shanghai University under the Shanghai University Ph.D. Programs, and
the Project of Establishing Shanghai University Institute for Sustainable
Energy Co-Funded by Shanghai Education Administration Committee
and Shanghai University.
References
[1] E.V. Global, Outlook 2020, IEA Publications, June 2020.
[2] Y. Ding, Z.P. Cano, A. Yu, J. Lu, Z. Chen, Automotive Li-Ion Batteries: current
Status and Future Perspectives, Electrochem. Energy Rev. 2 (2019) 1–28.
[3] Mineral Commodity Summaries, U.S. Geological Survey, U.S. Department of the
Interior, 2020. January 2020.
[4] Average cobalt spot price in the United States from 2008 to 2019 (in U.S. dollars
per pound), https://www.statista.com/statistics/339743/average-spot-price-ofcobalt-in-the-us/#:~:text=In%202019%2C%20the%20average%20spot,37.4%
20U.S.%20dollars%20per%20pound.
[5] S. Jewell, S.M. Kimball, Mineral Commodity Summaries, US Department of the
Interior, US Geological Survey, 2017.
[6] Mitch Jacoby, It’s time to recycle lithium-ion batteries, Chem. Eng. News 97 (28)
(2019) 29–32. https://pubs.acs.org/doi/10.1021/cen-09728-cover.
[7] L. Li, X. Zhang, M. Li, R. Chen, F. Wu, K. Amine, J. Lu, The recycling of spent
lithium-ion batteries: a review of current processes and technologies,
Electrochem. Energy Rev. 1 (2018) 461–482.
[8] Chow N., Jung J., Nacu A., Warkentin D., Processing of cobaltous sulphate/
dithionate liquors derived from cobalt resource, United State Patent 10308523
B1, June (2019).
[9] H. He, Z.Y. Zhang, L. Alai, F.S. Zhang, A. Green, Process for exfoliating electrode
materials and simultaneously extracting electrolyte from spent lithium-ion
batteries, J. Hazard. Mater. 375 (2019) 43–51.
[10] J. Li, Y. Lu, T. Yang, D. Ge, D. Wood, Z. Li, Water-based electrode manufacturing
and direct recycling of lithium-ion battery electrodes – a green and sustainable
manufacturing system, iScience 23 (May) (2020), 101081.
[11] F. Larouche, F. Tedjar, K. Amouzegar, G. Houlachi, P. Bouchard, G.
P. Demopoulos, K. Zaghib, Progress and status of hydrometallurgical and direct
recycling of Li-ion batteries and beyond, Materials (Basel) 13 (801) (2020).
[12] J. Kasnatscheew, R. Wagner, M. Winter, C. Cekic-Laskovic, Interfaces and
materials in lithium ion batteries: challenges for theoretical electrochemistry,
Top. Curr. Chem. 376 (2018) 16.
[13] M. Grutzke, V. Kraft, W. Weber, C. Wendt, A. Friesen, S. Klamor, M. Winter,
S. Nowak, Supercritical Carbon Dioxide Extraction of Lithium-ion Battery
Electrolytes, J. Supercrit. Fluids 94 (2014) 216–222.
[14] M. Grutzke, X. Monnighoff, F. Horsthemke, V. Kraft, M. Winter, S. Nowak,
Extraction of lithium-ion battery electrolytes with liquid and supercritical carbon
dioxide and additional solvents, RSC Adv. 43209 (May) (2015).
[15] X. Monnighoff, A. Friesen, B. Konersmann, F. Horsthemke, M. Grutzke, M. Winter,
S. Nowak, Supercritical Carbon Dioxide Extraction of Electrolyte from Spent
19
J.C.-Y. Jung et al.
Journal of Energy Storage 35 (2021) 102217
[47] G. Furlani, F. Pagnanelli, L. Toro, Reductive acid leaching of manganese dioxide
with glucose: identification of oxidation derivatives of glucose, Hydrometallurgy
81 (2006) 234–240.
[48] F. Pagnanelli, M. Garavini, F. Veglio, L. Toro, Preliminary screening of
purification processes of liquor leach solutions obtained from reductive leaching
of low-grade manganese ores, Hydrometallurgy 71 (2004) 319–327.
[49] F. Veglioi, M. Trifoni, L. Toro, Leaching of manganiferous ores by glucose in a
sulfuric acid solution: kinetic modeling and related statistical analysis, Ind. Eng.
Chem. Res. 40 (2001) 3895–3901.
[50] E. Sayilgan, T. Kukrer, G. Civelekoglu, F. Ferella, A. Akcil, F. Veglio, M. Kitis,
A review of technologies for the recovery of metals from spent alkaline and zinccarbon batteries, Hydrometallurgy 97 (2009) 158–166.
[51] J. Xu, H.R. Thomas, R.W. Francis, K. Lum, J. Wang, Liang Bo, A review of
processes and technologies for the recycling of lithium-ion secondary batteries,
J. Power Sources 177 (2008) 512–527.
[52] B. Swain, J. Jeong, J.C. Lee, G.H. Lee, Development of process flow sheet for
recovery of high pure cobalt from sulfate leach liquor of lib industry waste: a
mathematical model correlation to predict optimum operational conditions, Sep.
Purif. Technol. 63 (2008) 360–369.
[53] C. Lupi, M. Pasquali, Electrolytic nickel recovery from lithium-ion batteries,
Miner. Eng. 16 (2003) 537–542.
[54] J. Nan, D. Han, D. Han, X. Zuo, Recovery of metal values from spent lithium-ion
batteries with chemical deposition and solvent extraction, J. Power Sources 152
(2005) 278–284.
[55] G. Zante, A. Braun, A. Masmoudi, R. Barillon, D. Trebouet, M. Boltoeva, Solvent
extraction fractionation of manganese, cobalt, nickel and lithium using ionic
liquids and deep eutectic solvents, Miner. Eng. 156 (2020), 106512.
[56] Y. Sun, M. Zhu, Y. Yao, H. Wang, B. Tong, Z. Zhao, A novel approach for the
selective extraction of Li+ from the leaching solution of spent lithium-ion
batteries using benzo-15-crown-5 ether as extractant, Sep. Purif. Technol. 237
(2020), 116325.
[57] L. Sun, K. Qiu, Organic oxalate as leachant and precipitant for the recovery of
valuable metals from spent lithium-ion batteries, Waste Manage. 32 (2012)
1575–1582.
[58] X. Zheng, W. Goa, X. Zhang, M. He, X. Lin, H. Cao, Y. Zhang, Z. Sun, Spent
lithium-ion battery recycling – Reductive ammonia leaching of metals from
cathode scrap by sodium sulphite, Waste Manage. (Oxford) 60 (February) (2017)
680–688.
[59] C. Wu, B. Li, C. Yuan, S. Ni, L. Li, Recycling valuable metals from spent lithiumion batteries by ammonium sulfite-reduction ammonia leaching, Waste Manage.
(Oxford) 93 (15 June) (2019) 153–161.
[60] S.Y. Moon, S.H. Hong, T.Y. Kim, Metabolic engineering of escherichia coil for the
production of malic acid, Biochem. Eng. J. 40 (2008) 312–320.
[61] E.P. Donald, G.W. Gellan, IFT’s Food Technology Industrial Achievement Award,
Food Technol. 47-9 (1993) 94–96.
[62] L. Li, J. Ge, R. Chen, F. Wu, S. Chen, X. Zhang, Environmental friendly leaching
reagent for cobalt and lithium recovery from spent lithium-ion batteries, Waste
Manage. (Oxford) 30 (2010) 2615–2621.
[63] S. Zhou, Y. Zhang, Q. Meng, P. Dong, Z. Fei, Q. Li, Recycling of LiCoO2 cathode
material from spent lithium ion batteries by ultrasonic enhanced leaching and
one-step regeneration, J. Environ. Manage. 277 (2021), 111426.
[64] Y. Zhang, Q. Meng, P. Dong, J. Duan, Y. Lin, Une of grape seed as reductant for
leaching of cobalt from spent lithium-ion batteries, J. Ind. Eng. Chem. 66 (2018)
86–93.
[65] Q. Meng, Y. Zhang, P. Dong, A combined process for cobalt recovering and
cathode material regeneration from spent LiCoO2 batteries: process optimization
and kinetics aspects, Waste Manage. (Oxford) 71 (2018) 372–380.
[66] Q. Meng, Y. Zhang, P. Dong, F. Liang, A novel process for leaching of metals from
LNi1/3Co1/3Mn1/3O2 material of spent lithium ion batteries: process
optimization and kinetics aspects, J. Ind. Eng. Chem. 61 (2018) 131–141.
[67] Q. Meng, Y. Zhang, P. Dong, Use of electrochemical cathode-reduction method for
leaching of cobalt from spent lithium-ion batteries, J. Cleaner Prod. 180 (2018)
64–70.
[68] L. Li, J. Ge, F. Wu, R. Chen, S. Chen, B. We, Recovery of Cobalt and Lithium from
spent lithium ion batteries using organic citric acid as leachant, J. Hazard. Mater.
176 (2010) 288–293.
[69] R. Golmohammadzadeh, F. Rashchi, E. Vahidi, Recovery of lithium and cobalt
from spent lithium-ion batteries using organic acids: process optimization and
kinetic aspects, Waste Manage. (Oxford) 64 (June) (2017) 244–254.
[70] B. Musariri, G. Akdogan, C. Dorfling, S. Bradshaw, Evaluating organic acids as
alternative leaching reagents for metal recovery from lithium ion batteries,
Miner. Eng. 137 (15 June) (2019) 108–117.
[71] L. Zhuang, C. Sun, T. Zhou, H. Li, A. Dai, Recovery of valuable metals from
LiNi0.5Co0.2Mn0.3O2 cathode materials of spent Li-ion batteries using mild mixed
acid as leachant, Waste Manage. (Oxford) 85 (15) (2019) 175–185. February.
[72] X. Chen, H. Ma, C. Luo, T. Zhou, Recovery of valuable metals from waste cathode
materials of spent lithium-ion batteries using mild phosphoric acid, J. Hazard.
Mater. 326 (15 March) (2017) 77–86.
[73] L. Li, J. Lu, Y. Ren, X.X. Zhang, R. Chen, F. Wu, K. Amine, Ascorbic acid assisted
recovery of cobalt and lithium from spent li-ion batteries, J. Power Source 218
(2012) 21–27.
[74] Y. Fu, Y. He, H. Chen, C. Ye, Q. Lu, R. Li, W. Xie, J. Wang, Effective leaching and
extraction of valuable metals from electrode material of spent lithium-ion
batteries using mixed organic acids leachant, J. Ind. Eng. Chem. 79 (25) (2019)
154–162. November.
[75] D. Mishra, D.J. Kim, D.E. Ralph, J.G. Ahn, Y.H. Rhee, Bioleaching of metals from
spent lithium ion secondary batteries using Acidithiobacillus Ferrooxidans, Waste
Manage. 28 (2008) 333–338.
[76] B. Xin, D. Zhang, X. Zhang, Bioleaching mechanism of Co and Li from spent
lithium-ion battery by the mixed culture of acidophilic sulphur-oxidising and
iron-oxidising bacteria, Bioresour. Technol. 100-24 (2009) 6163–6169.
[77] G. Zeng, X. Deng, S. Luo, X. Luo, J. Zou, A Copper-catalyzed bioleaching process
for enhancement of cobalt dissolution from spent lithium-ion batteries, J. Hazard.
Mater. 199-200 (2012) 164–169.
[78] M. Silverman, D. Lundgren, Studies on the chemoautotrophic iron bacterium
ferrobacillus ferrooxidans I. An improved medium and a harvesting procedure for
securing high cell yields, J. Bacteriol. 77 (1959) 642–647.
[79] T. Huang, L. Liu, S. Zhang, Recovery of cobalt, lithium, and manganese from the
cathode active materials of spent lithium-ion batteries in a bio-electrohydrometallurgical process, Hydrometallurgy 188 (2019) 101–111.
[80] W. Song, J. Liu, L. You, S. Wang, Q. Zhou, Y. Gao, R. Yin, W. Xu, Z. Guo, Resynthesis of nano-structured LiFePO4/graphene composite derived from spent
lithium-ion battery for booming electric vehicle application, J. Power Sources
419 (April) (2019) 192–202.
[81] Q. Sun, X. Li, H. Zhang, D. Song, X. Shi, J. Song, C. Li, L. Zhang, Resynthesizing
LiFePO4/C materials from the recycled cathode via a green full-solid route,
J. Alloys Compd. 818 (2020), 153292.
[82] J. Li, Y. Wang, L. Wang, B. Liu, H. Zhou, A facile recycling and regeneration
process for spent LiFePO4 batteries, J. Mater. Sci.: Mater. Electronics 30 (2019)
14580–14588.
[83] X. Jiang, P. Wang, L. Li, J. Yu, Y. Yin, F. Hou, Recycling process for spent cathode
materials of LiFePO4 batteries, Mater. Sci. Forum 943 (2019) 141–148.
[84] X. Song, T. Hu, C. Liang, H.L. Long, L. Zhou, W. Song, L. You, Z.S. Wu, J.W. Liu,
Direct regeneration of cathode materials from spent lithium iron phosphate
batteries using a solid phase sintering method, RSC Adv. 7 (8) (2017) 4783–4790.
[85] X. Li, J. Zhang, D. Song, J. Song, L. Zhang, Direct regeneration of recycled
cathode material mixture from scrapped LiFePO4 batteries, J. Power Sources 345
(2017) 78–84.
[86] J. Chen, Q. Li, J. Song, D. Song, L. Zhang, X. Shi, Environmentally friendly
recycling and effective repairing of cathode powders from spent LiFePO4
batteries, Green Chem. 18 (8) (2016) 2500–2506.
[87] D. Bian, Y. Sun, S. Li, Y. Tian, Z. Yang, X. Fan, W. Zhang, A novel process to
recycle spent LiFePO4 for synthesizing LiFePO4/C hierarchical microflowers,
Electrochim. Acta 190 (2016) 134–140.
[88] E. Shin, S. Kim, J.K. Noh, D. Byun, K.Y. Chung, H.S. Kim, B.W. Cho, A green
recycling process designed for LiFePO4 cathode materials for Li-ion batteries,
J. Mater. Chem. A 3 (21) (2015) 11493–11502.
[89] F. Forte, M. Pietrantonio, S. Pucciarmati, M. Puzone, D. Fontana, Lithium iron
phosphate batteries recycling: an assessment of current status, Crit. Rev. Environ.
Sci. Technol. 1054-3389 (2020) 1547–6537.
[90] Y. Yang, X. Zheng, H. Cao, C. Zhao, X. Lin, P. Ning, Y. Zhang, W. Jin, Z. Sun,
A closed-loop process for selective metal recovery from spent lithium iron
phosphate batteries through mechanochemical activation, ACS Sustain. Chem.
Eng. 5 (2017) 9972–9980.
[91] K. He, Z.Y. Zhang, F.S. Zhang, A green process for phosphorus recovery from
spent LiFePO4 batteries by transformation of delithiated LiFePO4 crystal into
NaFeS2, J. Hazard. Mater. 395 (2020), 122614.
[92] P. Yadav, C.J. Jie, S. Tan, M. Srinivasan, Recycling of cathode from spent lithium
iron phosphate batteries, Recycling of cathode from spent lithium iron phosphate
batteries, J. Hazard. Mater. 300 (2020), 123068.
[93] J. Zhang, J. Hu, Y. Liu, Q. Jing, C. Yang, Y. Chen, C. Wang, Sustainable and facile
method for the selective recovery of lithium from cathode scrap of spent LiFePO4
batteries, ACS Sustain. Chem. Eng. 7 (6) (2019) 5626–5631.
[94] L. Li, J. Lu, L. Zhai, X. Zhang, L. Curtiss, Y. Jin, F. Wu, R. Chen, K. Amine, A facile
recovery process for cathodes from spent lithium iron phosphate batteries by
using oxalic acid, CSEE J. Power Energy Syst. 4 (2) (2018) 219–255.
[95] Y. Yang, X. Meng, H. Cao, X. Lin, C. Liu, Y. Sun, Y. Zhang, Z. Sun, Selective
recovery of lithium from spent lithium iron phosphate batteries: a sustainable
process, Green Chem. 20 (13) (2018) 3121–3133.
[96] Q. Jing, J. Zhang, Y. Liu, C. Yang, B. Ma, Y. Chen, C. Wang, E-pH diagrams fort he
Li-Fe-P-H2O system from 298 to 473 K: thermodynamic analysis and application
to the wet chemical processes of the LiFePO4 cathode material, J. Phys. Chem. C
123 (23) (2019) 14207–14215.
[97] L. Li, Y. Bian, X. Zhang, Y. Yao, Y. Xue, E. Fan, F. Wu, R. Chen, A green and
effective room-temperature recycling process of LiFePO4 cathode materials for
lithium-ion batteries, Waste Manage. (Oxford) 85 (2019) 437–444.
[98] S. Tao, J. Li, L. Wang, L. Hu, H. Zhou, A method for recovering Li3PO4 from spent
lithium iron phosphate cathode material through high-temperature activation,
Ionics (Kiel) 25 (12) (2019) 5643–5653.
[99] R. Zheng, L. Zhao, W. Wang, Y. Liu, Q. Ma, D. Mu, R. Li, C. Dai, Optimized Li and
Fe recovery from spent lithium-ion batteries via a solution-precipitation method,
RSC Adv. 6 (49) (2016) 43613–43625.
[100] Tedjar F., Foudraz J.C., Method for the mixed recycling of lithium-based anode
batteries and cells, US Patent No: US7820317B2 (2010).
[101] H. Li, S. Xing, Y. Liu, F. Li, H. Guo, G. Kuang, Recovery of lithium, iron, and
phosphorus from spent LiFePO4 batteries using stoichiometric sulfuric acid
leaching system, ACS Sustain. Chem. Eng. 5 (9) (2017) 8017–8024.
[102] G. Cai, K.Y. Fung, K.M. Ng, C. Wibowo, Process development for the recycle of
spent lithium ion batteries by chemical precipitation, Ind. Eng. Chem. Res. 53
(47) (2014) 18245–18259.
20
J.C.-Y. Jung et al.
Journal of Energy Storage 35 (2021) 102217
[103] Schurmans M., Thijs B., Process for the recovery of lithium and iron from LFP
batteries, Patent Application WO2012072619A1, (2012).
[104] Y. Song, L. He, Z. Zhao, X. Liu, Separation and recovery of lithium from Li3PO4
leaching liquor using solvent extraction with saponified D2EHPA, Sep. Purif.
Technol. 229 (2019), 115823.
[105] X. Wang, X. Wang, R. Zhang, Y. Wang, H. Shu, Hydrothermal preparation and
performance of LiFePO4 by using Li3PO4 recovered from spent cathode scraps as
Li source, Waste Manage. (Oxford) 78 (2018) 208–216.
[106] Y. Huang, G. Han, J. Liu, W. Chai, W. Wang, S. Yang, S. Su, A stepwise recovery of
metals from hybrid cathodes of spent Li-ion batteries with leaching-flotationprecipitation process, J. Power Sources 325 (2016) 555–564.
[107] Z. Li, D. Liu, J. Xiong, L. He, Z. Zhao, D. Wang, Selective recovery of lithium and
iron phosphate /carbon from spent lithium iron phosphate cathode material by
anionic membrane slurry electrolysis, Waste Manage. (Oxford) 107 (2020) 1–8.
[108] Cardarelli F., Dube J., Method for Recycling Spent Lithium Metal Polymer
Rechargeable Batteries and Related Materials, US Patent No: US 7,192,564 B2,
(2007).
[109] M. Assefi, S. Maroufi, Y. Yamauchi, V. Sahajwalla, Pyrometallurgical recycling of
Li-ion, Ni-Cd, and Ni-MH batteries: a minireview, Curr. Opin. Green Sustain.
Chem. 24 (2020) 26–31.
[110] P. Meshram, B.D. Pandey, T.R. Mankhd, Extraction of lithium from primary and
secondary sources by pre-treatment, leaching, and separation: a comprehensive
review, Hydrometallurgy 150 (2014) 192–208.
[111] T. Georgi-Maschler, B. Friedrich, R. Weyhe, H. Heegn, M. Rutz, Development of a
recycling process for Li-ion batteries, J. Power Sources 207 (2012) 173–182.
[112] T. Trager, B. Friedrich, R. Weyhe, Recovery concept of value metals from
automotive lithium-ion batteries, Chem. Ing. Tech. 87 (11) (2015) 1550–1557.
[113] Q. Liang, H. Yue, S. Wang, S. Yang, K.H. Lam, X. Hou, Recycling and crystal
regeneration of commercial used LiFePO4 cathode materials, Electrochim. Acta
330 (10) (2020), 135323. January.
[114] Y. Tang, H. Xie, B. Zhang, X. Chen, Z. Zhao, J. Qu, P. Xing, H. Yin, Recovery and
regeneration of LiCoO2-based spent lithium-ion batteries by a carbothermic
reduction vacuum pyrolysis approach: controlling the recovery of CoO or Co,
Waste Manage. (Oxford) 97 (September) (2019) 140–148.
[115] D. Wang, X. Zhang, H. Chen, J. Sun, Separation of Li and Co from the active mass
of spent Li-ion batteries by selective sulfating roasting with sodium bisulfate and
water leaching, Miner. Eng. 125 (September) (2018) 28–35.
[116] W. Wang, Y. Han, T. Zhang, L. Zhang, S. Xu, Alkali metal salt catalyzed
carbothermic reduction for sustainable recovery of LiCoO2: accurately controlled
reduction and efficient water leaching, ACS Sustain. Chem. Eng. 7 (2019)
16729–16737.
[117] AkkuSer Oy, https://www.akkuser.fi/en/home/.
[118] American Manganese Inc., https://americanmanganeseinc.com/.
[119] Brunpt Recycling, https://www.catl.com/en/solution/recycling/.
[120] Direct Recycling and OnTo Technology LLC, https://www.bestmag.co.uk/content
/play-it-again-steve%E2%80%94-how-direct-recycling-can-repair-battery-cath
odes.
[121] S. Sloop, L. Crandon, M. Allen, K. Koetje, L. Reed, G. Gaines, W. Sirisaksoontorn,
M. Lerner, A direct recycling case study from a lithium-ion battery recall, Sustain.
Mater. Technol. 25 (2020) e00152.
[122] Li-Cycle Corp., https://li-cycle.com/technology/.
[123] Lithion Recycling Inc., https://www.lithionrecycling.com/lithium-ion-battery
-recycling-process/.
[124] S. Nowak, M. Winter, Recycling of Lithium Ion Batteries, Wiley Analytical
Science, 2018.
[125] S. Nowak, M. Winter, The role of sub- and supercritical CO2 as “processing
solvent” for the recycling and sample preparation of lithium ion battery
electrolytes, MDPI, Molecules 22 (March) (2017) 403.
[126] Retriev Technologies Inc., https://www.retrievtech.com/lithiumion.
[127] Smith W., Swoffer S., Process for recovering and regenerating lithium cathode
material from Lithium-ion Batteries, US Patent # 8,882,007 B1, Nov (2014).
[128] Sumitomo Metal Mining Co. spent battery recycling process for lithium-ion
batteries https://www.recyclingtoday.com/article/japanese-company-develops
-lithium-ion-battery-recycling-process/, March (2019).
[129] T. Elwert, D. Goldmann, F. Romer, M. Buchert, C. Merz, D. Schueler, J. Sutter,
Current developments and challenges in the recycling of key components of
(hybrid) electric vehicles, Recycling 1 (2016) 25–60.
[130] Umicore battery recycling process, https://csm.umicore.com/en/battery-recyc
ling/our-recycling-process/.
[131] W.C. Lih, J.H. Yen, F.H. Shieh, Y.M. Liao, Second use of retired lithium-ion
battery packs from electric vehicles: technological challenges, cost analysis and
optimal business model, in: 2012 International Symposium on Computer,
Consumer and Control, 2012.
[132] L. Gaines, Profitable recycling of low-cobalt lithium-ion batteries will depend on
new process developments, One Earth 1 (Dec) (2019).
[133] D. Steward, A. Mayyas, M. Mann, Economics and challenges of Li-ion battery
recycling from end-of-life vehicles, Procedia Manuf. 33 (2019) 272–279.
[134] Low Cost, High Margins: lithium Brine Extraction | INN (investingnews.com), htt
ps://investingnews.com/innspired/lithium-brine-extraction-electric-vehicle-mar
ket/ Nov (2018).
[135] Y. Yao, M. Zhu, Z. Zhao, B. Tong, Y. Fan, Z. Hua, Hydrometallurgical processes for
recycling spent lithium-ion batteries: a critical review, ACS Sustain. Chem. Eng. 6
(2018) 13611–13627.
[136] L. Gaines, The future of automotive lithium-ion battery recycling: charting a
sustainable course, Sustain. Mater. Technol. 1-2 (2014) 2–7.
[137] Y.J. Park, M.K. Kim, H.K. Kim, B.M. Lee, Risk assessment of lithium-ion battery
explosion: chemical leakages, J. Toxicol. Environ. Health, Part B 21 (6) (2019)
370–381.
[138] S. Hogg, Batteries need to be ‘renewable’ too: why recycling matters now, Energy
Storage News (Sept) (2019).
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