Transcript
Aqueous Binders for Lithium Ion Battery
Presented by Wenquan Lu Electrochemical Energy Storage Chemical Sciences and Engineering Argonne National Laboratory Aug. 2014
Outline
Why Aqueous Binder for Lithium Ion Batteries Results and Discussions – Aqueous binder for carbon anode – Aqueous binder for cathode – Aqueous binder for future silicon electrode Future works
Why Aqueous Binders for Lithium Ion Battery Technically as electrode: high adhesion as battery: high capacity
Different binding mechanism Point vs. PVDF
Cost Shorting drying Cheap material No recycling Environmentally Organic solvent free
3
SBR for Anode SBR is becoming popular as a binder for carbon anode electrode.
Failed First Attempt to Make Graphite Electrode Using SBR as Binder
Li/Graphite cell 0V~1.5V C/10 rate
0.6
Voltage, V
Anode Graphite (A12, Phillips66 ) SBR (TRD2001, JSR) CMC (MAC350HC, Nippon Paper) Carbon black (C45, Timcal)
0.8
0.4
0.2
0.0 0
100
200
300
400
Capacity, mAh/g
Mixing temperature is critical to make good electrode.
SBR Composition Effect on Electrode Making Anode Graphite (A12, Phillips66 ) SBR (TRD2001, JSR) CMC (MAC350HC, Nippon Paper) Carbon black (C45, Timcal) electrode
Residuals on substrate (%)
tape
30
2%
4%
6%
8%
27 24 21 18 15 12 9 6 3 0 1
2
3
4
5
6
7
8
9
Percent of SBR in electrodes(%)
Balanced adhesion and cohesion was observed when lower amount of SBR is used.
Formation of Li/graphite Cells Using SBR 3rd discharge 0.8
2% SBR 4% SBR 6% SBR 8% SBR
Voltage (V)
0.6
0.4
Li/graphite cell 1.5V~0V C/10 rate
SBR (%)
0.2
Theoretical Test capacity capacity (mAh) (mAh)
2
4.88
4.61
338
4
4.51
4.14
324
6
4.30
3.43
270
8
4.33
3.03
225
0.0 0
50
100
150
200
250
300
350
Capacity (mAh/g)
Normal capacity (mAh/g)
The graphite electrode with lower SBR content shows higher reversible capacity.
SBR Effect on Electrode Impedance EIS
HPPC 120
2% SBR 6% SBR 8% SBR
-50
2% SBR 4% SBR 6% SBR 8% SBR
110 100 90
-40
ASI (ohm-cm2)
80
Z''
-30
-20
70 60 50 40 30 20
-10
10 0
0 0
50
100
Z'
150
200
0
10
20
30
40
50
60
70
DOD (%)
lower impedance were observed for the graphite electrode with lower SBR content. Larger semicircle indicates higher interfacial resistance.
80
Aqueous Binder for Cathode Materials
Lithium manganese rich transition metal oxide (LMRNMC) Cathode Binder/cathode/Carbon/CMC: x/93-x/5/2 (x=1, 2, 4) LMR-NMC (HE5050, Toda) FA (TRD202A, JSR) CMC (MAC350HC, Nippon Paper) Carbon black (C45, Timcal)
Formation of LMR-NMC half cell with 1% binder TRD202A
8% PVDF
5.0
5.0
2.0V~4.6V; CC (C/10): 0.25 mA 1.2M LiPF6 EC/EMC (3/7) Li/LMR-NMC half cell
4.5
4.5
4.0
Voltage, V
Voltage (V)
4.0
charg-1 charg-2 charg-3 disch-1 disch-2 disch-3
3.5
1st Charge 1st Discharge 2nd Charge 2nd Discharge 3rd Charge 3rd Discharge
3.0
2.5
2.0 0
50
100
150
3.5
Li/NCM cell 4.6V~2.0V 0.343mA 1st charg: 300mAh/g 1st disch: 249mAh/g ICL: 17%
3.0
2.5
wql200 200
Specific Capacity (mAh/g)
250
300
2.0
327 0
50
100
150
200
Capacity, mAh
Almost identical electrochemical performance was obtained for the electrode with TRD 202A compared to that with PVDF binder.
250
300
Electrochemical Performance of LMR-NMC using Fluorine Acrylic Latex Binder 240
HPPC
Rate
Specific Capacity (mAh/g)
230 220 210 200 190 180 170 0.0
1% SX 1% 2% 2% 2% 4% 4% 0.4
0.8
1.2
1.6
2.0
C Rate
HE5050 Cycle
– high specific capacity 244 mAh/g, – low Ohmic resistance <50 Ω•cm2, – excellent rate capability (> 178 mAh/g at 2C), and – outstanding capacity retention (>87% after 50 cycles). 11
Total Aqueous Binder Lithium Ion Battery Formation
Cycling
HPPC
Lithium ion battery with all aqueous binders for both anode and cathode were demonstrated. For graphite/LMR-NMC system, no obvious negative effect on electrochemical performance was observed. 12
Silicon Electrode Development Silicon-based negative electrodes have a better chance to meet the PHEV energy requirements due to their adjustable high capacities. Their utilization, however, still waits on developing the high capacity, stable active anode material PLUS developing non-active components (additives & binders), establishing testing protocols, and optimizing electrode engineering.
VOLUME EXPANSION mechanical integrity
PHASE TRANSITION structural stability
SOLID ELECTROLYTE INTERFACE parasitic side reactions
COLLECTIVE EFFORTS MATERIAL DEVELOPMENT
particle size; morphology; composites
ELECTRODE OPTIMIZATION INTERFACIAL MODIFICATION binder; formulation
additives; surface modification
TEST CONDITIONS
temp.; cut-off voltages
13
Silicon Electrode and Binder Binders tested: – – – – – –
Poly(vinylidenefluoride) (PVDF) Polyacrylic Acid (PAA) Na-Alginate Poly Amine Imide (PAI) carboxymethyl cellulose (CMC) Styrene-Butadiene Rubber (SBR)
Li/Si-C cell
1.2M LiPF6 in EC/EMC with 3 wt% FEC
5mV to 2V
General Electrode composition – 10% C-45 – 30% Silicon – 45% A12 Graphite – 15% Binder
Better cycle performances of silicon electrode were obtained when PAA or alginic acid binders were used as binder. 14
What makes PAA Better for Silicon Electrode Binder
Pros
Cons
PVDF
• Good electrode coating
• Does not cycle
CMC
• Carboxylic groups lead strong bonding with metal foil
• Low CMC concentration leads to low loading
Li-PAA
• More carboxylic groups • High degree of cyclability • Doesn’t hydrolyze well in water
• Binder tends to trap air bubbles Laminates can be brittle
NaAlginate
• High degree of cyclability • Relatively inexpensive • Easy to mix
• Short shelf life • Laminates can be brittle • Sodium ions add extra inactive material
PAI
• Makes a good electrode coating • Can cycle well with silicon
• NMP is the required solvent • Complex curing process
PAA
Optimization of Silicon Electrode The electrode using PAA as a binder is brittle.
Electrode after cycling 2500
Specific Capacity (mAh/g)
C/10 2000 1500
C/5
C/3
C/2
Si:Graphene:PAA = 70:10:20
2C
1C
CC 70:10:20 CC 70:10:15:5
1000
Si:Graphene:PAA:SBR = 70:10:15:5
500 0 0
5
10
15
20
Cycle Number (#)
SBR addition improved the electrode integrity and electrochemical performance.
Summary
In the work, the aqueous binder for lithium ion battery application has been investigated for both anode and cathode. We successfully made the full cells using graphite anode and high energy density lithium manganese rich metal oxide cathode. The preliminary results indicate that the full cell using aqueous binders only has the comparable electrochemical performance. The aqueous binder for future anode material, silicon, was also studied. In this case, the aqueous binder is “the must” for performance. The cost reduction or environmental effect will be considered in the next phase.
Acknowledgement
Qingliu Wu Joseph Kubal Miranda Miguel Steve Trask Bryant Polzin Andrew Jansen SeonBaek Ha (IIT) Jai Prakash (IIT) Dennis Dees
JSR: Jim Banas Nippon paper
Support from David Howell and Peter Faguy of the U.S. Department of Energy’s Office of Vehicle Technologies is gratefully acknowledged.
