High Energy Rechargeable Li-S Battery Development at … Mikhayl… · High Energy Rechargeable Li-S Battery Development at ... Li-S cell capacity and allow charge control ... solar

The Rechargeable Battery Company

®

High Energy Rechargeable

Li-S Battery Development at

Sion Power and BASF

Y. Mikhaylik*, C. Scordilis-Kelley*, M. Safont*, M. Laramie*, R. Schmidt**, H. Schneider**,

K. Leitner**

*Sion Power Corporation, **BASF SE

1 IBA2013, Barcelona, March11-15

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2

Outline

Fundamentals of Li-S electrochemical system.

Current status of 350 Wh/kg Sion Power cells and their

high power and extreme low temperature variations.

Sion Power and BASF approach for next generation of

Li-S technology.


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Fundamentals of Li-S electrochemical system Theoretical Energy Density Comparison

DG ~ - 425 kJ/mol

OCV ~ 2.2 V

Energy density ~ 2800 Wh/L

Specific Energy ~ 2500 Wh/kg

Compare Specific Energy with:

Li-ion ~ 580 Wh/kg

TNT equivalent ~ 1280 Wh/kg

S + 2Li = Li2S

IBA2013, Barcelona, March11-15

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1.8

2.0

2.2

2.4

0.00 0.25 0.50 0.75 1.00 1.25 1.50

Electrons per S atom

Vo

lta

ge

1256 mAh/g

1

2

3

4

Voltage Deep due to

Li2S Nucleation

Polarization

1. Slightly soluble elemental

sulfur reduction to soluble Li2S8

S8 + e- + Li+ Li2S8

2. Soluble Li2S8 reduction to

soluble Li2S4

Li2S8 + e- + Li+ Li2S4

3. Soluble Li2S4 reduction to

solid Li2S and partially Li2S2

Li2S4 + e- + Li+ Li2S+Li2S2

4. High polarization due to

exhaustion of soluble Li2S4 and

porosity blocking by solid Li2S

Up to 1500 mAh/g capacity can

be gained at rates below C/50

Typical Li-S cell discharge profile at room

temperature and rates C/10 - C/2

Fundamentals of Li-S electrochemical system

Discharge mechanism


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Discharge profilers at low rate

and temperatures below –40oC

showed multi-step sulfur

reduction.

-30

-25

-20

-15

-10

-5

0

5

1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4

Voltage

dQ

/dV

+ 25 oC

-0.9

-0.8

-0.7

-0.6

-0.5

-0.4

-0.3

-0.2

-0.1

0

0.1

1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4Voltage

dQ

/dV

- 50 oC

Differential

discharge capacity

at -50 oC suggests

existence of up to 6

intermediate sulfur

reduction species.

Fundamentals of Li-S electrochemical system

Discharge mechanism

1.2

1.6

2

2.4

0 0.1 0.2 0.3 0.4 0.5 0.6

Ah

Vo

ltag

e

- 40 oC


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Fundamentals of Li-S electrochemical system Polysulfide shuttle mechanism

Soluble Li2Sx

species on the

Upper Plateau

diffuse to the anode

where they are

reduced to lower

polysulfides.

This results in

Rapid Self-

Discharge and loss

of the Upper

Plateau capacity,

~400 mAh/gS.

Polysulfide

Shuttle


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Typical charge (C/8) and discharge (C/5)

profiles with strong shuttle.

NOX compounds chemically protect Li anode, suppress the

shuttle, restore Li-S cell capacity and allow charge control

at 99.8% efficiency


Typical charge (C/8) and discharge (C/5)

for cells containing Nitrate.

Sion’s shuttle inhibitors permit near 100% utilization of the high voltage

plateau sulfur and up to 75% of total sulfur utilization at C/10 - C/5 rates.

1.7

1.9

2.1

2.3

2.5

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4V

olt

ag

e

Specific Capacity, Ah/g

First Discharge

All Recharges

Subsequent Discharges

1.7

1.9

2.1

2.3

2.5

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4

Vo

ltag

e

Specific Capacity, Ah/g

First Discharge

All Recharges

Subsequent Discharges

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Chemical protection of Li from polysulfide

shuttle

Charge

2.0

2.1

2.2

2.3

2.4

2.5

0 100 200 300 400 500

Time, min

Vo

lta

ge

23

24

25

26

27

28

Te

mp

era

ture

Ambient temperature

Cell temperature

Voltage

Charge

2.0

2.1

2.2

2.3

2.4

2.5

0 50 100 150 200 250 300

Vo

lta

ge

23

24

25

26

27

28

29

30

Te

mp

era

ture

Ambient temperature

Cell temperature

Voltage

Cells without protection from shuttle

showed significant overcharge and

heat generation while charged at upper

plateau. Soluble polysulfides were not

converted into elemental sulfur

Cells protected from shuttle can be

charged completely and demonstrated

endothermic effects at upper plateau

when soluble polysulfides were

converted into elemental sulfur.


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Current status of 350 Wh/kg Sion Power cells

with chemically protected Li anode


Wound Prismatic

37mm x 55mm x 11mm

17 grams

350 Wh/kg

320 Wh/l

-20°C to + 45°C operating

temp.

30 to 60 cycles @ 100%

DOD

25 mΩ impedance

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First Commercial Li-S Application is

Unmanned Aerial Vehicles - UAVs

Flew to >70,000 ft where temperature is < -60oC.

QinetiQ's Zephyr 7 UAV Captures World Record for

Longest Duration Flight (unmanned or otherwise).

23 meter Wing Span

July, 2010

Used solar power to fly & recharge batteries by day.

New World Record: >14 days of continuous flight.

Flight was powered by Sion Li-S batteries at night.


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Charge and Discharge Profiles at -60 oC

0.0

0.5

1.0

1.5

2.0

2.5

3.0

0.0 0.5 1.0 1.5 2.0 2.5

Ah

Vol

tage

Charge

50 mA to 2.95 V

Discharge

2500 mA to 1.0 V

Batteries with modified electrolyte delivered:

1)~160 Wh/kg at -60oC at 1C,

2)~130 Wh/kg at -70oC at 1C,

3) The battery can be recharged at -60°C.

2.5A Discharge Profiles

0.0

0.5

1.0

1.5

2.0

2.5

3.0

0.0 0.5 1.0 1.5 2.0 2.5 3.0

Discharge Capacity, Ah

Vo

lta

ge

- 70oC

- 60oC

+ 20oC

Current status of 350 Wh/kg Sion Power cells Low Temperature Modification

Work was partially supported by NASA Glenn Research Center.

Contract NNC06CA85C


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Cell design and active materials balance modification

Specific Energy vs Cycle

0

50

100

150

200

250

300

350

400

0 20 40 60 80 100

Cycle

Wh

/kg

Standard Cells

2.8 Ah

16 g

Experimental Cells

4.8 Ah

27 g

Work was partially supported by NASA Johnson Space Center.

Contract NNJ10JA74P


Optimizing active

and cell

construction

materials balance

allows prolonged

cycle life at high

specific energy

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0

1000

2000

3000

4000

0% 20% 40% 60% 80% 100%

Cell DoD

Sp

ecif

ic P

ow

er,

W/k

g

30 A

20 A


Cell design modification for high power

Optimized cell designs were

able to deliver specific power

up to 2000 W/kg at

continuous discharge

(currents up to 15 A) and

over 3000 W/kg for 10 s

duration high current pulses

for wide range of cell Depth

of Discharge (DoD)


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Ragone plot, comparing specific

energy to specific power of Li-S to

conventional battery chemistries.

Li-Ion Li-Iron Phosphate

Continuous

discharge up to

2 kW/kg.

30 A pulses up

to 3.3 kW/kg.

ASR = 10-26

Ω•cm2 (Cell area

specific

resistance)

Li-S Parameters


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Addressing Remaining Challenges Keys to the EV Market for Lithium-Sulfur

Cycle life of Li-S cells with chemically protected Li anode is

limited to ~ 100 cycles for 350 Wh/kg and higher specific

energies designs.

Elevated temperature stability/safety is limited to ~ 150 oC

Causes of the problems:

Development of rough lithium morphology affecting cycle

life and safety.

Lithium/Electrolyte depletion affecting cycle life and

capacity through cathode clogging.

Lithium reaction with sulfur and polysulfides affecting

thermal stability/safety.


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Lithium/Electrolyte depletion

Specific Energy-Cycle Life relationship for Sion Power experimental

cells


0

100

200

300

400

500

600

1 10 100 1000

Sp

ec

ific

En

erg

y,

Wh

/kg

Cycle Life to 80%

With excessive

amounts of electrolyte

and lithium cycle life

can exceed 500

cycles at 150 Wh/kg.

Reduced amounts of

electrolyte and Li lead

to 500 Wh/kg at the

expense of cycle life.

The key for success

is stopping electrolyte

and Li depletion.

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O O

O OLi

MeOLi

O

CH4

MeSxLi

Li/Li2Sx

O O

O OLi

Li/Li2Sx

H2

RO

O OLi

n

High amount, highly soluble and highly

detrimental for S cathode performance.

Moderate amount, low solubility, neutral.

Small amount, soluble, consumes S.

Traces.

Traces.

Increases anode polarization

Traces

Highly soluble and highly detrimental

for S cathode performance.

Identified at Sion Power

Identified at Sion Power and by D. Aurbach, J. Electrochem. Soc.156,8. 2009.

1,2-Dimethoxyethane

Identified depletion products and their impact on battery performance.

The Chemistry of Electrolyte Solvent Depletion

1,3-Dioxolane


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Sion Power approach for next

generation Li-S technology

Suppressing rough Li morphology development through

externally applied uniaxial pressure

Physical protection of lithium with multi-functional

membrane assemblies:

– Multi-layer solid electrolyte ceramic/polymer coating

– Gel electrolyte

– Dual-phase electrolyte

Optimize cathode structure and porosity to limit pore

blocking and increase sulfur specific capacity


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47 um

60 um

No pressure Li anode cycled under pressure

Suppressing rough Li morphology development through

externally applied uniaxial pressure

Proprietary design with applied uniaxial pressure allowed for

increased charging rate without developing in Li anode surface

roughness.

0

400

800

1200

1600

0 50 100 150Cycle

Sp

ec

ific

Ca

pa

cit

y, m

Ah

/g

Conventional

design

Proprietary

design

Charge Current Changed from:

an 8-hour charge

to a 2.5-hour charge

Experimental batteries cycling behavior


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Sion Power BASF approach for

next generation Li-S technology

Physically Protected Li Anode

Work is partially supported by USA Department of Energy. Contract DE-AR0000067


Gel-Electrolyte Polymer layer

Protective layer

Vacuum Deposited Lithium

After cycling at C/5

SEM image of Protected Li Anode

cross-section after cycling in the

electrochemical cell

Working electrode

surface

Back-side electrode

surface

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Dual Phase Electrolyte Li-S Battery “Anode” Liquid 1:

• Immobilized within polymeric gel applied to anode.

• Stable with lithium preventing side reactions and dendrite growth.

• Immiscible with Phase 2 electrolyte and does not dissolve polysulfides.

• Polymeric gel can serve as coated separator.

“Cathode” Liquid 2:

• Tailored to improve high energy Sion Power sulfur cathode performance.

• Immiscible with Phase 1 electrolyte.

• High ion conductivity and lithium polysulfide solubility.

Sion Power approach for next

generation Li-S technology

Work is partially supported by USA Department of Energy. Contract DE-EE0001997


Li Anode Lio

Gel-Polymer Li +

No Li2Sx Solubility with

Liquid 1 Li +

Li +

Porous

Carbon-Sulfur

Cathode

with Liquid 2

Charge

Discharge

S8 Li2S8 Li2S6 Li2S4 Li2S3 Li2S2 Li2S

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Safety Improved by Sion-BASF Gel Layer

including Dual-Phase Electrolyte and Cycling

Under Pressure

Fully charged experimental Li-S cells ramped at 5 oC/min after 10 cycles

-5

15

35

55

75

95

100 120 140 160 180 200 220 240

Heater Temperature, oC

Tcell

- T

Heate

r, o

C

Sulfur

meltingLi

melting

No

compressionExternal

uniaxial

pressure

Sion-BASF

Protective

Layer

and

Compression

There was no

thermal runaway for

cells surpassing the

melting point of

metallic lithium.

Molten lithium and

molten sulfur were

kept apart, and Li

protected cells

experienced only

about 3-8 ºC

temperature rise

above ambient.


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Progress on cathode structure

Improved pore

structure provides

cathode functioning

under pressure

without pores

clogging and with

increased sulfur

utilization.

This development paves the way to increasing specific energy from the

current 350 Wh/kg to the 550 Wh/kg needed to achieve a 500 km EV range


0

400

800

1200

1600

0 2000 4000 6000 8000

Sp

ec

ific

Ca

pa

cit

y, m

Ah

/g

Specific Discharge Rate, mA/g S

C/30

C/3

10C

1C

2C 4C

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Next Generation Li-S Technology

Sion Power is moving to the next generation with new

anode and cathode materials to enable a quantum leap

in performance.

Sion’s breakthrough anode protection technology will

enable higher energy densities and safety than

previously possible.

– Already demonstrated techniques in the laboratory that extend

cycle life while inhibiting thermal runaway in Li-S cells.

Manufacturing technology utilizes standard methods for

cell and battery assembly.

Volume cost for Sion’s Li-S battery is expected to meet

or beat long term cost targets for EV commercialization.

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Sion Power Partners in Development

January 12, 2012 – BASF announced that it has invested

$50 million to acquire an equity ownership position in

privately held Sion Power, the global leader in the

development of lithium-sulfur (Li-S) batteries, based in

Tucson, Arizona.

This equity partnership expands upon an existing joint

development agreement that BASF Future Business

GmbH established with Sion Power in 2009 to accelerate

the commercialization of Sion’s proprietary Li-S battery

technology for electric and plug-in electric vehicles and

other high-energy applications over the next decade.


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Sion Power Corporation, in collaboration with

BASF, is very optimistic that the future of all

EV applications will be dominated by Sion

Power’s lithium-sulfur technology.

Takeaway


Documents

High Energy Rechargeable Li-S Battery Development at … Mikhayl… · High Energy Rechargeable Li-S Battery Development at ... Li-S cell capacity and allow charge control ... solar