Supplementary Information
An Aqueous Rechargeable Lithium Battery Using Coated Li Metal as Anode
Xujiong Wang 1, Yuyang Hou 1, Yusong Zhu 1, Yuping Wu 1,*, Rudolf Holze 2
1. Preparation of cathode material: All reagents were of analytical grade. LiMn2O4 nanochains
were synthesized by a starch-assisted sol–gel method. In a typical synthesis, 0.4 g starch was
placed in a flask and 25 ml distilled H2O was added into the flask. The resulting mixture was
heated initially at 110 °C until the solution became transparent under stirring (acted as solution A).
Then 5 mmol manganese nitrate (50%) and 2.5 mmol lithium nitrate were added together and
dissolved in water to get a homogeneous solution (acted as solution B). Solution B was added into
solution A under stirring and then the mixture was kept at 110 °C for 1.5 h. The resultant mixture
was dried initially at 110 °C to get the precursor in the form of foam. The dried foam was further
heated at 250 °C for 3 h followed by a thermal treatment at 700 °C for 3 h to get LiMn2O4. SEM
micrograph and XRD of the as-prepared materials were shown in Fig.S1 and Fig.S2.
2. Materials characterization. XRD patterns were collected using a Rigaku D/MAX-IIA X-ray
diffractometer with Cu Kα radiation. SEM micrograph was obtained with a Philips XL30
microscope operated at 25 kV.
3. SEM micrograph of the prepared LiMn2O4 nanochain
Figure S1. SEM micrograph of LiMn2O4 nanochain.
SEM micrograph of the cathode LiMn2O4 material is shown in Figure S1. The spinel exists in a
nanochain morphology and consists of beads of about 100 nm. This kind of nanostructure presents
very excellent cycling behavior and rate performance in aqueous electrolyte as shown in the
following.
4. X-ray diffraction (XRD) pattern of the prepared LiMn2O4 nanochain
X-ray diffraction (XRD) pattern is shown in Figure S2. The diffraction peaks at 18.3°, 36.3°, 38.0°,
44.1°, 48.3°, 58.2°, 63.8° and 67.2° are indexed to the characteristic diffractions of spinel
LiMn2O4. Its crystallinity is not very high, which may be due to the nanostructure of LiMn2O4.
1
New Energy and Materials Laboratory (NEML), Department of Chemistry, Fudan University,
Shanghai 200433, China. Correspondence and requests for materials should be addressed to Y.W
(e-mail: wuyp@fudan.edu.cn).
2 Technische Universität Chemnitz, Institut für Chemie, AG Elektrochemie, D-09107 Chemnitz,
Germany.
Intensity (a.u.)
LiMn2O4 nanochain
JCPDS file No.35-0782
20
40
60
80
o
2 Theta ( )
Figure S2. XRD of LiMn2O4 nanochain.
5. Cyclic voltammograms of the coated Li metal anode and the LiMn2O4 cathode in 0.5 mol
l-1 Li2SO4 aqueous solution
0.020
0.006
(a)
0.004
LiMn2O4
Current (A)
Current (mA)
0.002
0.000
Li metal
-0.002
-0.004
-1
0.016
(b)
0.012
LiMn O
2 4
1 mV s
-1
3 mV s
-1
5 mV s
-1
10mV s
-1
15mV s
-1
20mV s
-1
30mV s
-1
50mV s
0.008
0.004
0.000
-0.004
-0.008
-0.012
-0.006
-4.0
-3.5
-3.0
-2.5
-2.0 0.0
0.5
1.0
1.5
0.0
0.3
Potential (V vs. SCE)
0.6
0.9
1.2
Potential (V vs. SCE)
Figure S3. CV curves of (a) the coated lithium metal as anode and the LiMn2O4 nanochain as
cathode and (b) the LiMn2O4 cathode at different scans in the 0.5 mol l-1 Li2SO4 aqueous solution.
The CV curves of the coated lithium metal as anode and the LiMn2O4 nanochain as cathode in the
0.5 mol l-1 Li2SO4 aqueous solution are shown in Figure S3. In the case of LiMn2O4, there are two
anodic peaks situated at 0.82 and 0.96 V (vs. SCE), respectively, which correspond to the
de-intercalation of Li+ ions from the tetrahedral 8a and octahedral 16c sites in the LiMn2O4 spinel.
On the reverse scan, two cathodic peaks at 0.70 and 0.83V (vs. SCE) can be ascribed to
intercalation of Li+ into LiMn2O4. As to the redox of Li, during the positive and negative scan, the
Li metal anode undergo the plating of Li metal from -3.1 V (vs. SCE) and the dissolving of Li
metal at - 2.4 V (vs. SCE), respectively. Combining these results, the calculated redox peaks of
integrated battery are consistent with those of CV curves shown in Figure 2.
80
100
60
80
Capacity
Coulomb efficiency
60
Current density: 500 mA g
40
40
-1
20
In aqueous electrolyte
20
0
0
50
100
150
0
200
Cycle number
140
120
100
(b)
80
100
60
80
Capacity
Efficiency
60
40
Current density: 100 mA g-1
In organic electrolyte
40
20
0
20
0
0
5
10
15
20
25
Coulomb efficiency (%)
100
(a)
120
Discharge capacity (mAh g-1)
-1
140
Coulomb efficiency (%)
Discharge capacity (mAh g )
6. The cycling performance of the prepared LiMn2O4 in aqueous and organic electrolytes
30
Cycle number
Figure S4. Cycling performance of cathode LiMn2O4 in (a) 0.5 mol l-1 Li2SO4 aqueous electrolyte
and (b) 1 mol l-1 LiPF6 solution of dimethyl carbonate, diethyl carbonate and ethylene carbonate
S2
(volumetric ratio = 1:1:1).
The cycling performance of the cathode LiMn2O4 in the aqueous and organic electrolytes is shown
in Figure S4. The reversible capacity of the cathode LiMn2O4 does not change evidently after 200
cycles at a current density of 500 mA g-1 in the aqueous solution. This indicates that LiMn2O4
shows an excellent cycling performance in our designed ARLB. In contrast, since LiMn2O4 is not
doped, its capacity fades very fast within 30 cycles in the organic electrolyte, which is similar to
results of previous reports.
7. The charge and discharge curves of the prepared LiMn2O4 at different charge and
discharge current densities in 0.5 mol l-1 Li2SO4 aqueous solution
Voltage (V vs.SCE)
1.2
1.0
0.8
0.6
-1
500 mA g charge
-1
500 mA g discharge
-1
1000 mA g charge
-1
1000 mA g discharge
-1
5000 mA g charge
-1
5000 mA g discharge
-1
10000 mA g charge
-1
10000 mA g discharge
0.4
0.2
0.0
0
20
40
60
80
100
120
-1
Capacity (mAh g )
Figure S5. Galvanostatic charge-discharge curves of LiMn2O4 cathode at different current
densities.
The nanochain LiMn2O4 shows a discharge capacity of 100 mAh g-1 at charge/discharge current
densities of 1000 mA g-1, 97 mAh g-1 at those of 5000 mA g-1 and 95 mAh g-1 even at those of
10000 mA g-1 between 0 - 1.05 V. The flat plateaus in the charge and discharge curves are
well-defined at all current densities and the voltage decrease is mild at very high current densities.
This excellent rate capability in the aqueous solution is very rare in the organic electrolytes.
S3