 Electrochemistry Basics
- electrochemical cells & ion transport
- electrochemical potential
- half-cell reactions
 Lithium Ion Batteries (LiBs)
- battery materials
- application of batteries
- “post-LiBs”
 Fuel Cell Basics & Applications
- fuel cell types and materials
- basic electrocatalysis
- H2 reduction & O2 reduction kinetics
- transport resistances
- cell-reversal & start-stop degradation
2012-05-22 AMS Battery & FC Lectures - Battery (Michele P. for Hubert G.).ppt
p. 30
Lithium Ion Batteries (LiBs) - Solvents
 use of (metallic) lithium electrodes requires aprotic organic electrolytes
Li  Li  e
;E(0Li / Li)  3.045 V ( -1 standardreduction potential)
H  e  0.5 H2
;E(0H / H2)  0 V
Li  H  Li  0.5 H2
;E(0H / H2)  3.045 V
 Li unstable with H+ (and H2O)
 aprotic organic solvents
from: K. Xu; Chem. Rev. 104 (2004) 4303
2012-05-22 AMS Battery & FC Lectures - Battery (Michele P. for Hubert G.).ppt
p. 31
Lithium Ion Batteries - Solvents
 requirements: - high dielectric constant (e)
- low viscosity (h)
- low melting point (Tm), high boiling point (Tb), high flash point (Tf)
 propylene carbonate (PC) seems almost perfect
(1958: first Li-plating from PC)
2012-05-22 AMS Battery & FC Lectures - Battery (Michele P. for Hubert G.).ppt
from: K. Xu; Chem. Rev. 104 (2004) 4303
p. 32
Lithium Ion Batteries - Salts
 lithium salts soluble in aprotic electrolytes  aprotic organic electrolytes
from: K. Xu; Chem. Rev. 104 (2004) 4303
 requirements: - complete dissociation  high conductivity (s)
- oxidative/reductive stability
- thermal stability (high Tdecomposition)
- chemical stability towards all cell components (e.g., Al current collector)
2012-05-22 AMS Battery & FC Lectures - Battery (Michele P. for Hubert G.).ppt
p. 33
Positive Electrodes for LiBs
 TiS2 : first reversible Li+ intercalation compound (Whittingham, 1973)
 x Li  x e  TiS2  Lix TiS2
(singlephase within x  0 - 1)
- TiS2 sheets
- hexagonal close-packed S-lattice
- S stacking sequence ABABAB
from: M.S. Whittingham; Chem. Rev. 104 (2004) 4271
 specific capacity  theoretical capacity normalized by weight
(referenced to lithiated/de-lithiated compound for positive/negative electrode)
s
 CLiTiS

2
 specific energy:
96485 As mol
As
mAh
 811
 225
119 g mol
gLiTiS2
gLiTiS2
s
s
WLiTiS
[
mWh
/
g
]

C
[mWh / gLiTiS2 ]  E( vs .Li / Li)
LiTiS
LiTiS
2
2
2
2012-05-22 AMS Battery & FC Lectures - Battery (Michele P. for Hubert G.).ppt
p. 34
Li / TiS2 Battery
Li // 2.5M LiClO4 in DL // TiS2 at 10 mA/cm2 (25C)
from: M.S. Whittingham; Chem. Rev. 104 (2004) 4271
(M.S. Whittingham; Prog. Solid State Chem. 12 (1978) 41; 790 cits.)
  E( vs .Li / Li)  2.0 V
s
 WLiTiS
 450mWh / gLiTiS2
2
note: dioxolane was used, since PC
co-intercalated with Li+ into TiS2
 first large automotive LiB in 1977
using LiAl-alloy negative electrode
(0.2 V vs. Li/Li+; used for safety reasons)
from: M.S. Whittingham; Chem. Rev. 104 (2004) 4271
2012-05-22 AMS Battery & FC Lectures - Battery (Michele P. for Hubert G.).ppt
p. 35
Li Metal Negative Electrode
 highest specific capacity (3800 mAh/gLi )
 but, formation of dendrites (safety!)
& shape-change (loss of active material)
from: K. Xu; Chem. Rev. 104 (2004) 4303
 in addition:
continuous reduction of electrolyte
 no lithium-metal electrodes in
today’s rechargeable LiBs
2012-05-22 AMS Battery & FC Lectures - Battery (Michele P. for Hubert G.).ppt
p. 36
LiC6 Negative Electrode (Sony 1990)
 Li+ insertion in between graphene planes of graphite  up to 1 Li+ per 6 C


 Li  x e  6 C  LiC6 , with CCs 
 ELixC vs. Li+/Li
96485 As mol
mAh
 372
72 g mol
gC
 no Li-plating (ELixC > ELi )
 no shape-change (fixed C-”cage”)
 but, …
2012-05-22 AMS Battery & FC Lectures - Battery (Michele P. for Hubert G.).ppt
from: R.A. Huggins; Advanced Batteries (Springer, 2009)
p. 37
Solid Electrolyte Interface (SEI)
 SEI: electrolyte reduction products on LixC or Li (fluorides from LiBF4 or LiPF6)
 Li+-conducting, but
electronically insulating (20 Å)
 prevents continuous electrolyte reduction
 Li+ consumed for initial SEI formation
(batteries must be built with excess Li+)
 but, …
from: K. Xu; Chem. Rev. 104 (2004) 4303
2012-05-22 AMS Battery & FC Lectures - Battery (Michele P. for Hubert G.).ppt
p. 38
Graphite Electrode Defoliation
 strong solvation of Li+ with PC  intercalation of PC into graphite
 prevents formation of stable SEI w. PC
 EC, however, forms stable SEI
 need to add DMC, DEC, or EMC
to increase conductivity at  25C
 stable negative graphite electrode 
 lithium must be introduced via
the positive electrode materials
(does not work, e.g., with TiS2)
from: K. Xu; Chem. Rev. 104 (2004) 4303
2012-05-22 AMS Battery & FC Lectures - Battery (Michele P. for Hubert G.).ppt
p. 39
Positive Intercalation Electrode with Li
 discovery of LiCoO2 (layer compound) in 1980:
 reversible inter-/deintercalation of Li+
between LiCoO2 and Li0.45CoO2
0.55 Li+ + 0.55 e– + Li0.45CoO2  LiCoO2
s
CLiCoO

2
0.55  96485 As mol
mAh
 150
98 g mol
gLiCoO2
 graphite // alkylcarbonates + LiPF6 // LiCoO2 developed by Sony in 1990
is the currently predominant LiB system
from: R.A. Huggins; Advanced Batteries (Springer, 2009)
2012-05-22 AMS Battery & FC Lectures - Battery (Michele P. for Hubert G.).ppt
p. 40
LiB – Summary
from: B. Dunn, H. Kamath, J.M. Tarascon; Science 334 (2011) 928
2012-05-22 AMS Battery & FC Lectures - Battery (Michele P. for Hubert G.).ppt
p. 41
Electrolyte Filled Separator
 porous polymer matrix: electrolyte reservoir
& electronic insulation
estimated ionic resistance:
Rareal 
t separator
selectrolyte  e electrolyte 
1.5
from: P. Arora & . Zhang; Chem. Rev. 104 (2004) 44193
2012-05-22 AMS Battery & FC Lectures - Battery (Michele P. for Hubert G.).ppt
p. 42
Battery Assembly
 spiral-wound cylindrical design (for high energy batteries: pouch or prismatic cells)
 note: commonly the negative electrode is referred to as anode and the positive
electrode as cathode (based on the discharge reaction)
typical dimensions:
- negative current collector (Cu): 10 mm
- positive current collector (Al): 20 mm
- separator:
25 mm
- separator:
25 mm
- electrodes: - high power
- high energy
20-40 mm
60-100 mm
 for high energy LiBs:
2.5 mAh/cm2  4V  10 mWh/cm2
 huge area for electric vehicle batteries!
from: P. Arora & . Zhang; Chem. Rev. 104 (2004) 44193
2012-05-22 AMS Battery & FC Lectures - Battery (Michele P. for Hubert G.).ppt
p. 43
Ragone Plots
 celates specific energy to specific power (rate)
 C-rate is defined as specific power/specific energy [1/h]
from: B. Dunn, H. Kamath, J.M. Tarascon; Science 334 (2011) 928
2012-05-22 AMS Battery & FC Lectures - Battery (Michele P. for Hubert G.).ppt
p. 44
 Electrochemistry Basics
- electrochemical cells & ion transport
- electrochemical potential
- half-cell reactions
 Lithium Ion Batteries (LiBs)
- battery materials
- application of batteries
- “post-LiBs”
 Fuel Cell Basics & Applications
- fuel cell types and materials
- basic electrocatalysis
- H2 reduction & O2 reduction kinetics
- transport resistances
- cell-reversal & start-stop degradation
2012-05-22 AMS Battery & FC Lectures - Battery (Michele P. for Hubert G.).ppt
p. 45
Electromobility Challenges: BEVs
Tesla EV (2009)
 battery system weight & cost:
120 Whname-plate/kgsystem (Tesla)  highest Wh/kg battery pack, but very complex system
 400 km range (53 kWhname-plate): 450 kg and  13000 € (2030 projection*) )
 charging time: hour(s)
 safety:
short-term: higher Wh/kg electrode materials and/or high-cost system architecture
long-term: novel electrode and electrolyte materials
 safer and higher Wh/kg batteries are required for full BEVs
*) “Transitions
to Alternative Transportation Technologies – Plug-In Hybrid Electric Vehicles”,
National Research Council (2010); see: www.nap.edu/catalog/12826.html
2012-05-22 AMS Battery & FC Lectures - Battery (Michele P. for Hubert G.).ppt
p. 46
LiNiPO4
LiCoPO4
cathodes (positive)
Battery Materials/Concepts
modified from: J.-M. Tarascon & M. Armand,
Nature 414 (2001) 359
Li/air
anodes (negative)
Li/sulfur
silcon
2012-05-22 AMS Battery & FC Lectures - Battery (Michele P. for Hubert G.).ppt
p. 47
Battery Specific Energy [Wh/kgelectrodes ]
 higher Wh/kg: - 5V cathodes (Co,Mn,Fe-phosphoolivines, Mn-spinels)   25% gain
- higher specific capacity materials
LiNiPO4
LiCoPO4
modified from: J.-M. Tarascon & M. Armand,
Nature 414 (2001) 359
Li/air
Li/sulfur
silcon
 “post-LiB”: Li/air and Li/S batteries with Si-based anodes
2012-05-22 AMS Battery & FC Lectures - Battery (Michele P. for Hubert G.).ppt
p. 48
Battery Materials
 anodes:
 cathodes:
 durability, safety, and cost are additional critical considerations
from: Lamm, A.; Warthmann, W.; Soczka-Guth, T.; Kaufmann, R.; Spier, B.; Friebe, P.; Stuis, H.; Mohrdieck;
“Lithium-Ionen Batterie – Erster Serieneinsatz im S400 Hybrid“; ATZ (07-0812009) 2009, 111, 490.
2012-05-22 AMS Battery & FC Lectures - Battery (Michele P. for Hubert G.).ppt
p. 49
Limit of Lithium-Ion Batteries
 spec. energy of C-anodes & NMC-cathodes:
LiNixMnyCozO2 / C
specific capacity of electrodes [Ah/kgelectrodes]:
110
cathode voltage (positive) [V]
4.0
anode voltage (negative) [V]
0.1
battery voltage [V]
specific energy of electrodes [Wh/kgelectrodes]:
3.9
Cs  Cs
where C 
(Cs  Cs )
s

430
 specific of cells and battery-packs:
- electrodes: 70% of cell weight
(rest: current collectors & electrolyte)
 LiNixMnyCozO2 / C: 300 Wh/kgcell
 long-term projection:
200 Wh/kgbattery-pack
(from F.T. Wagner et al.)
2012-05-22 AMS Battery & FC Lectures - Battery (Michele P. for Hubert G.).ppt
from: F.T. Wagner, B. Lakshmanan,
M.F. Mathias; J. Phys. Chem.
Lett. 1 (2010) 2204
p. 50
BEV Battery Weight & Cost
 projected performance of today’s LiB technology: - 200 Wh/kgbattery-pack*)
- 95% discharge efficiency
- 80% state-of-charge range
- 250 €/kWhname-plate**)
 energy required for small 4-passenger car:
- 100 Wh/km*)
150 km range
500 km range
15 kWhnet
50 kWhnet
20 kWhname-plate
66 kWhname-plate
battery weight:
100 kg
330 kg
battery cost:
5000 €
16500 €
required net energy:
required name-plate energy:
 current cost & weight 2-fold higher
 fast charging  increases perceived range
*) F.T.
**)
Wagner, B. Lakshmanan, M.F. Mathias; J. Phys. Chem. Lett. 1 (2010) 2204
“Transitions to Alternative Transportation Technologies – Plug-In Hybrid Electric Vehicles”,
National Research Council (2010); see: www.nap.edu/catalog/12826.html
2012-05-22 AMS Battery & FC Lectures - Battery (Michele P. for Hubert G.).ppt
p. 51
Rapid Charging
 charging time vs. power: kWhelectricity / kWcharging = tcharging
from:
E.ON presentation
at the IAS Opening
by J. Eckstein
(Oct. 22, 2010)
 rapid charging: impacts battery life & business case of electric utilities
 long-range BEVs need advanced batteries
2012-05-22 AMS Battery & FC Lectures - Battery (Michele P. for Hubert G.).ppt
p. 52
Battery Targets for 500 km BEVs
 battery requiriements for 500 km-range small 4-passenger cars:
- 70 kWhname-plate
 < 200 kg weight  > 350 Wh/kgbattery-pack
- 35 kW constant power
 C-rate of 0.5 h-1 (continuous)
- 100 kW accelerating power
 C-rate of 1.5 h-1 (short-term)
- 25000 km life (50% avg. charge)
 > 1000 cycles
- <10000 € battery cost
 < 150 €/kWhname-plate (15 €/m2cell !)
 current LiB technology will not meet the long-range Wh/kg requirements
 Wh/l of concern for current car architectures:
 380 kg / 500 l (ICE)  430 kg / 350 l (20kWh BEV)
 alternative batteries – “post-LiBs” ?
2012-05-22 AMS Battery & FC Lectures - Battery (Michele P. for Hubert G.).ppt
p. 53
 Electrochemistry Basics
- electrochemical cells & ion transport
- electrochemical potential
- half-cell reactions
 Lithium Ion Batteries (LiBs)
- battery materials
- application of batteries
- “post-LiBs”
 Fuel Cell Basics & Applications
- fuel cell types and materials
- basic electrocatalysis
- H2 reduction & O2 reduction kinetics
- transport resistances
- cell-reversal & start-stop degradation
2012-01-31 AMS Battery & FC Lectures – Fuel Cell - 1 (Hubert G.).ppt
p. 54
Li-S Batteries
S + 2 Li+ + 2 e-  (Li2S)solid
2 Li  2 Li+ + 2 e-
Li  + eLi2S2
& Li2S
e-
e-
e-
Li2S2/Li2S
S8
Li2S8
Li+
e-
Li2S6
Li+
Li2S4
Li+
Li+
poly-sulfide redox-shuttle
Li2S4
Li-electrode
current-collector
separator
current-collector
2 Li + S  (Li2S)solid ; E0  2.0 VLi
+
sulfur-electrode (e.g., porous carbon)
 challenges & development needs:
- polysulfide diffusion to anode
 Li+-conducting diffusion-barrier
- poor C-rate & cathode “clogging”  cathode design
- stable anode configuration
 improved Li-metal anode design or alternative
2012-01-31 AMS Battery & FC Lectures – Fuel Cell - 1 (Hubert G.).ppt
p. 55
Li-S Batteries: State-of-the-Art
Cathode / Electrolyte / Anode
C+S / liquid electrolyte / Li
C+S / liquid+solid-electrolyte/ Li
C+S / polymer electrolyte / Li
C+Li2S / liquid electrolyte / Si
C+Li2S / polymer electrolyte / Sn
S-Utilization
70%
70%
70-50%
40%
40%
C-Rate
0.10 h-1
0.20 h-1
0.20 h-1
0.13 h-1
0.20 h-1
Cycles
20
150
200
20
100
Ref.
[1]
[2]
[3]
[4]
[5]
[1] X. Ji, K.T. Lee, L.F. Nazar; Nature Materials 8 (2009) 500.
[2] SION Power presentation; ORNL Symposium on Scalable Energy Storage Beyond Li-Ion:
Materials Perspective (Oct. .2010)
https://www.ornl.gov/ccsd_registrations/battery/presentations/Session7-1020-Affinito.pdf.
[3] G. Ivanov (Oxis Energy Ltd.); (Jan. 2010); Oxis web site:
http://www.oxisenergy.com/downloads/Recent%20progress%20Polymer%20Li-S_2010.pdf;
[4] J. Li, R.B. Lewis, J.R. Dahn; Electrochem. & Solid-State Lett. 10 (2007) A17.
[5] H.S. Ryu, Z. Guo, H.J. Ahn, G.B. Cho, H. Liu; J. Power Sources 189 (2009) 1179.
 increased cycle-life with poly-sulfide diffusion barriers
 still insufficient performance: - S-utilization  70% vs. 90% target
- C-rate  0.2 h-1 vs. 0.5 h-1 target
- cycle-life  200 cycles vs. 2000 cycle target
 further advances needed, also wrt. Li-metal safety
2012-01-31 AMS Battery & FC Lectures – Fuel Cell - 1 (Hubert G.).ppt
p. 56
Li-S Batteries: Metallic Li-Anodes
 supression of Li dendrite formation / shape-change is challenging
 alternative anode concepts ?
2012-01-31 AMS Battery & FC Lectures – Fuel Cell - 1 (Hubert G.).ppt
p. 57
spec. capacity of electrodes [Ah/kg]
Anode Effect on Wh/kg
900
800
C  C
C electrodes 
(C   C  )
700
600
500
Si-anode
400
Li-anode
300
C-anode
200
100
0
0
500
1000
1500
2000
2500
3000
3500
specific capacity of negative electrode [Ah/kg]
 high capacity anodes essential for Li-S & Li-air batteries
 Si-anodes (Li15Si4): volumetric expansion (4x) is challenging
2012-01-31 AMS Battery & FC Lectures – Fuel Cell - 1 (Hubert G.).ppt
p. 58
Wh/kg of LiB vs. Li/S
Li/air
Li/sulfur
 spec. capacity & energy projections:
J.-M. Tarascon & M. Armand,
Nature 414 (2001) 359
silcon
LiNixMnyCozO2 / C
Li2S / Si
specific capacity of electrodes [Ah/kgelectrodes]:
110
630
cathode voltage (positive) [V]
4.0
2.0
anode voltage (negative) [V]
0.1
0.5
battery voltage [V]
specific energy of electrodes [Wh/kgelectrodes]
3.9
1.5
430
950
gain vs. current batteries
2-fold
 2x Wh/kgbattery-pack gains projected for Li-S
2012-01-31 AMS Battery & FC Lectures – Fuel Cell - 1 (Hubert G.).ppt
p. 59
Li-Air Batteries: Thermodynamics
O2
O2 + 2 Li+ + 2 e-  (Li2O2)solid
2 Li  2 Li+ + 2 e2 Li + O2  (Li2O2)solid ; E0 = 2.96 VLi1)
 Li2O2 observed by ex-situ Raman2,3)
O2 + 4 Li+ + 4 e-  (Li2O)solid
Limetal
4 Li  4 Li+ + 4 e-
O2
4 Li + O2  (Li2O)solid ; E0 = 2.91
VLi1)
 partial Li2O formation via O2 balance4)
 evidence for Li2O2 & Li2O in organic electrolytes
 bulk-LiO2 only stable at 15 K5), but [LiO2]solvated in organic electrolytes
1) M.W.
Chase; NIST-JANAF Thermochemical Tables 4th Ed. (1998)
2) K.M. Abraham, Z. Jiang; J. Electrochem. Soc. 143 (1996) 1
3) A. Débart, A.J. Paterson, J. Bao, P.G. Bruce; Angew. Chem. Int. Ed. 47 (2008) 4521
4) J. Read; J. Electrochem. Soc. 149 (2002) A1190
5) L. Andrews, R. Smardzew; J. Chem. Phys. 58 (1973) 2258
2012-01-31 AMS Battery & FC Lectures – Fuel Cell - 1 (Hubert G.).ppt
p. 60
separator
current-collector
Li-Air Batteries: Processes
-
e
ec
c
c
Li2O2 / Li2O
c
Li+
Li
O2 (air)
LixO2
( H2O, CO2 )
Li2CO3
LiOH
Li-electrode
c
c
[ LiO2 ]solv. c
e-
+
porous air-electrode
 challenges:
- solid Li2O2/Li2O can clog electrodes and limit O2 & Li+ mass-transport
- O2, H2O, & CO2 can react on the lithium anode
2012-01-31 AMS Battery & FC Lectures – Fuel Cell - 1 (Hubert G.).ppt
p. 61
engineering
fundamentals
Challenges for Li/Air Batteries
 slow reaction rates at the air-cathode
 low round-trip efficiency ( 70%)
 low rate capability (C-rate  0.1 h-1)
 insufficient cycle-life (<50 cycles)
 reaction of O2 with carbonate-based electrolytes
 Li-metal electrode (dendrites, shape-change, corrosion)
(electro)catalysis,
electrode design
 open-system due to air-feed
 contamination/degradation from H2O-vapor & CO2
 electrolyte evaporation
 low volumetric energy density (air-feed channels)
 improved catalysts, electrodes, electrolytes, & Li+-ion selective separators
 high-risk / high-gain technology
2012-01-31 AMS Battery & FC Lectures – Fuel Cell - 1 (Hubert G.).ppt
p. 62
Wh/kg of LiB, Li/S, & Li/Air Electrodes
Li/air
Li/sulfur
 spec. capacity & energy projections:
J.-M. Tarascon & M. Armand,
Nature 414 (2001) 359
silcon
LiNixMnyCozO2 / C
Li2S / Si
Li2O / Si
specific capacity of electrodes [Ah/kgelectrodes]:
110
630
800
cathode voltage (positive) [V]
4.0
2.0
2.7
anode voltage (negative) [V]
0.1
0.5
0.5
battery voltage [V]
specific energy of electrodes [Wh/kgelectrodes]
3.9
1.5
2.2
430
950
1,700
2-fold
4-fold
gain vs. current batteries
 large Wh/kgbattery-pack gains projected for Li-S (2x) and Li-air (3x)
2012-01-31 AMS Battery & FC Lectures – Fuel Cell - 1 (Hubert G.).ppt
p. 63