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)

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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)

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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.

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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

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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

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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

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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

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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

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-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.

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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)

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(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

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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

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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)

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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)

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280°C 240°C

Zn

NaCl

(~10µm)

(50~80µm)

Na-ZnCl2 Battery

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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

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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.

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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