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Intermediate Temperature Planar Na-Metal Halide Batteries
2012 DOE EES Program Peer Review & Update Meeting Sept. 26~28, 2012 Washington DC
Jin Y. Kim, Guosheng Li, Xiaochuan Lu, John Lemmon, Vincent Sprenkle, Jun Cui, Brent Kirby, Nathan Canfield, Dave Reed, Kerry Meinhardt, Jeff Bonnett, Greg Coffey, Jirgal Mansonav, Gary Yang
Pacific Northwest National Laboratory R ichland, WA 99352
Sponsored by DOE EES Program (Program Manager: Dr. Imre Gyuk)
<2>
Sodium β”-Alumina Batteries (NBBs)
Batteries consisting of molten sodium anode and β"-Al2O3 solid electrolyte (BASE).
Use of low-cost, abundant sodium low cost High specific energy density (120~240 Wh/kg) Good specific power (150-230 W/kg)
Good candidate as a large-scale energy storage device for renewable energy Operated at relatively high temperature (300~350°C)
<3>
Na-S Battery vs. Na-Metal Halide Battery Sodium-sulfur (Na-S) battery
2Na + xS Na2Sx (x = 5~3) E = 2.08~1.78 V at 350°C
Sodium-nickel chloride (Zebra) battery 2Na + NiCl2 2NaCl + Ni
E = 2.58V at 300°C Use of catholyte (NaAlCl4)
Merits Safe cell failure mode Easiness of assembly in discharged state Less corrosive nature of cathode materials
Drawback Relatively expensive Cost reduction is a key issue to commercialize this technology for large energy storage applications.
<4>
Approaches to Reduce Cost
Intermediate Temperature (≤200°C) Na-NiCl2 Battery Use of economical construction materials and process such as polymer seals, enabling high throughput manufacturing methods
Low maintenance cost
Better cycle life by suppressing degradation mechanisms
Zn-Based Battery Replacement of nickel with low-cost zinc
<5>
Intermediate Temperature Na-NiCl2 Battery
Technical Challenges
High cell polarizations at reduced temperatures
Thick BASE tube (1~2 mm thick) Use of thin high-strength composite planar BASE
Catholyte NaAlCl4 (Tm = 157°C)
Wettability of Na melt on BASE at reduced temperatures
<6>
1.7
1.8
1.9
2.0
2.1
2.2
2.3
2.4
2.5
2.6
2.7
2.8
2.9
0 20 40 60 80 100
Volta
ge (V
)
State of Charge (%)
280°C (1st Cycle)280°C (3rd Cycle)280°C (6th Cycle)280°C (20th Cycle)
V vs. SoC cycled at various temperatures under C/3 rate
Cannot charge fully at 175⁰C, gradually shift to more discharged state
Na-NiCl2 Battery with Thin Planar BASE
1.7
1.8
1.9
2.0
2.1
2.2
2.3
2.4
2.5
2.6
2.7
2.8
2.9
0 20 40 60 80 100
Volta
ge (V
)
State of Charge (%)
200°C (1st Cycle)200°C (3rd Cycle)200°C (6th Cycle)200°C (20th Cycle)
1.7
1.8
1.9
2.0
2.1
2.2
2.3
2.4
2.5
2.6
2.7
2.8
2.9
0 20 40 60 80 100
Volta
ge (V
)
Stateof Charge (%)
175°C (1st Cycle, 9.8% deeper discharge)175°C (3rd Cycle, 1.4% deeper discharge)175°C (6th Cycle)175°C (20th Cycle)
280°C
200°C 175°C
Test conditions • 3 cm2 active area button cell • 1.5 g cathode (Ni, NaCl, NaAlCl4) • 60% Theoretical capacity (20-80% SoC) • 150 Whr/kg @ C/3
<7>
Cell voltage and corresponding resistance at various temperatures
0 10 20 30 40 50 602.5
2.6
2.7
2.8
2.9
Volta
ge (V
)
Cycle number
280°C 240°C 200°C 175°C
0 10 20 30 40 50 601.6
1.8
2.0
2.2
2.4
2.6
2.8
Volta
ge (V
)
Cycle number
280°C 240°C 200°C 175°C
0 10 20 30 40 50 602
4
6
8
10
Cell r
esist
ance
(Ω)
Cycle number
280°C 240°C 200°C 175°C
0 10 20 30 40 50 600
4
8
12
16
20
24
Cell r
esist
ance
( Ω)
Cycle number
280°C 240°C 200°C 175°C
End-of-charge voltage
End-of-discharge voltage
Polarization at the end of charge
Polarization at the end of discharge
Na-NiCl2 Battery with Thin Planar BASE
280°C
240°C
200°C
175°C
280°C
240°C
200°C
175°C
<8>
Backscattered electron images of the cathodes after 60 cycles
Na-NiCl2 Battery with Thin Planar BASE
280oC
240oC
175oC
Ni particle NaCl particles
NaCl ~ 50µm
Starting NaCl size ~ 10 μm, no growth observed after cycling at 175⁰C
NaCl ~ 25µm
<9>
-0.015
-0.010
-0.005
0.000
0.005
0.010
0.015
0.020
0.025
0.030
0.035
-0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5
Cur
rent
(A)
Voltage (V) vs. Al/Al3+
50% LiBr
50% NaBr
50% LiCl
Operating Voltage
NaAlCl4
Ionic Conductivity Electrochemical Window
Replacement of NaCl with lower melting-point salts
Robelin et. al, J. Chem. Thermodynamics (2004)
NaAlCl4 (Tm=157oC)
Low Tm Catholyte Development
• Decrease Tm of catholyte by 20 - 40°C • High ionic conductivity < 200°C with ≥ 25% salt replacement. • Does not impact electrochemical stability of catholyte.
<10> 0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
0 10 20 30 40 50
Volta
ge (V
)
Cycle Number
Voltage at the end of charge
Voltage at the end of discharge
Low Tm Catholyte Development Electrochemical Performance (50% NaCl replacement w/ NaBr)
Voltage vs. SOC (175°C) Impedance Plots
State of Charge (%)
0
10
20
30
40
50
60
70
80
90
100
0 10 20 30 40 50
Cap
acity
(mA
h)
Cycle Number
Charge Capacity(C/10)Discharge Capacity(C/10)
Capacity vs. Cycles (150°C, C/10)
Standard NaAlCl4 (175°C)
New Catholyte (175°C)
New Catholyte (150°C)
End-of-Step Voltage vs. Cycles (150°C, C/10)
New Catholyte
Standard NaAlCl4 (175°C)
<11>
(C/3 Discharge) (C/3 Discharge)
Low Temperature Na Wetting BASE Treatment on Anode Side
Limitation on charge pushed cycling window to more discharged state with cycling
Untreated (175°C) Anode-treated BASE (175°C)
BASE
Cathode
Na melt
Active Area
<12>
Na-ZnCl2 Battery Parthasarathy et al. *
Na-ZnCl2 battery with ZnCl2-NaCl catholyte Operate at high temperature (≥350°C) due to high eutectic point of ZnCl2-NaCl catholyte (Tm=253°C) ≥ 33 mol% ZnCl2 cannot be discharged to maintain the molten state of ZnCl2-NaCl catholyte Use of eutectic ZnCl2-NaCl catholyte makes the cell assembly in partially charged state (use of sodium in anode)
New Na-ZnCl2 Battery Cathode consists of active materials (NaCl + Zn), NaAlCl4 catholyte, and electrically conducting materials (metals, carbon, etc) in the form of powder, foam, mesh, etc. Assembled in discharged state (no addition of sodium in anode) Can be operated at relatively lower temperature (<300°C) Can fully utilize ZnCl2 during discharge * P. Parthasarathy, N. Weber, A.V. Virkar, ECS Trans. 6 (2007) 67
<13>
Na-ZnCl2 Battery vs. Na-NiCl2 Battery Na-ZnCl2 Battery
280°C (liquid phase formation) 1. 4NaCl + Zn ⇔ Na2ZnCl4 + 2Na E ~ 1.92 V 2. Na2ZnCl4 + Zn ⇔ Salt Liquid (ZnCl2: 62 mol%) + 2Na E ~ 2.07 V 3. Liquid (lower ZnCl2) + Zn ⇔ Liquid (higher ZnCl2) + 2Na E: 2.07~ 2.12 V 4. Salt Liquid (ZnCl2: 78 mol%) + Zn ⇔ ZnCl2 + 2Na E ~ 2.13 V 240°C (solid-state reactions) 1. 4NaCl + Zn ⇔ Na2ZnCl4 + 2Na 2. Na2ZnCl4 + Zn ⇔ ZnCl2 + 2Na
0.62 (280°C) 0.78 (280°C)
0.67(253°C)
<14>
Na-ZnCl2 Battery Cell voltage and corresponding resistance at 280°C and 240°C
C/3, 45% theoretical capacity
1.8
1.9
2.0
2.1
2.2
2.3
0 5 10 15 20 25 30
Cell
Volta
ge (V
)
Cycle Number
280°C (End of Charge)280°C (End of Discharge)240°C (End of Charge)240°C (End of Discharge)
1
2
3
4
5
6
7
8
0 5 10 15 20 25 30
Cell
Pola
rizat
aion
(Ohm
)
Cycle Number
280°C (End of Charge)280°C (End of Discharge)240°C (End of Charge)240°C (End of Discharge)
End of Step Voltage Cell Polarization at the end of step
280°C (Ch)
240°C (Ch)
240°C (Dch)
280°C (Dch) 280°C (Ch)
240°C (Ch)
<15>
280°C 240°C
Zn
NaCl
(~10µm)
(50~80µm)
Na-ZnCl2 Battery
<16>
Deep cycling (73% Theoretical capacity)
Na-ZnCl2 Battery
0 20 40 60 80 1001.6
1.8
2.0
2.2
2.4
2.6
2.8
3.0
Volta
ge (V
)
State of Charge (%)
1st cycle 10th cycle 30th cycle 40th cycle
280oC
0 10 20 30 40 50 601.7
1.8
1.9
2.0
2.1
2.2
2.3
2.4
Volta
ge (V
)
Cycle Number
End-of-charge Voltage End-of-discharge Voltage
Cell
Resi
sten
ce (Ω
)
280oC
0
1
2
3
4
5
6
7
8
Resistance at the end of charge Resistance at the end of discharge
280°C
Voltage vs. SOC Cell Polarization and Voltage at the end of step
<17>
Summary Intermediate Temperature Na-NiCl2 Battery
Intermediate temperature (≤200°C) Na-NiCl2 battery was successfully developed by incorporating thin planar BASE, low melting temperature catholyte, and anode-treated BASE. These cells show much reduced degradation compared to high temperature cells (at 175 with 60% cycling capacity under C/3; at 150°C with 53% cycling capacity under C/10).
New Na-ZnCl2 Battery
New Na-ZnCl2 battery with NaAlCl4 catholyte was successfully tested at 280°C at which electrochemical reactions include liquid phase formation. The formation of the liquid phase helps to decrease degradation possibly due to the suppression of particle growth This battery was capable of deep cycling up to >70% of theoretical capacity with good stability.
<18>
Future Work Large-scale cell test (64 cm2 active area) Long term test Other
Polymer seal development Thin BASE (≤50 µm) with porous support Investigation on degradation mechanisms
Publications X. Lu, G. Li, J.Y. Kim, J.P. Lemmon, V.L. Sprenkle, Z. Yang, “The Effects of Temperature on the Electrochemical Performance of Sodium-Nickel Chloride Batteries”, J. Power Sources 215 (2012) 288 G. Li, X. Lu, C.A Coyle, J.Y. Kim, J.P. Lemmon, V.L. Sprenkle, Z. Yang, “Novel ternary molten salt electrolytes for intermediate-temperature sodium/nickel chloride batteries,” J. Power Sources 220 (2012) 193 D.M. Reed, G.W. Coffey, E.S. Mast, N.L. Canfield, J. Mansurov, X. Lu, and V.L. Sprenkle, “Thin BASE (≤50 µm) with porous support,” J. Power Sources, submitted X. Lu, G. Li, J.Y. Kim, J.P. Lemmon, V.L. Sprenkle, Z. Yang, “Novel Sodium-Zinc Chloride Battery,” in preparation