Tadiran Confidential and Proprietary

Major Improvement

of the TMV

for

Li/SOCl2 System

H.Yamin ,A. Ulus and J. Heller

Tadiran Confidential and Proprietary

Outline

• Introduction

- TMV & the voltage delay phenomena

- TMV Improvement –historical perspective

• Experimental

- The electrochemical cells

- Test equipment

• Results & Discussion

- Pulse and discharge tests

- EIS & SEM study

Summary & Conclusions

2

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Introduction

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TMV & Voltage Delay Phenomena

Volt

age

Time

OCV

TMV

0

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Transition Minimum Voltage (TMV)

• The major drawback of Li/SOCl2 system is the voltage delay phenomenon

• Formation of LiCl film on the Li surface increases cell impedance with storage/operation time

• The ionic conductivity of the LiCl film is relatively low and its thickness is very difficult to be controlled

• Our idea is to coat the Li by a proprietary, unique and stable film

The TMV drawback

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Improvement of voltage delay- historical perspective

Gabano claims dissolving Li2O or Li2S in electrolyte

Carl Schlaikjer GTE Labs : Li2B10Cl10

Chua & Merz 5% SO2 in electrolyte

A.N. Dey Duracell SO2 caused film to acquire more orderly appearance

J.W. Boyd addition of PVC in electrolyte coat the lithium surface

Fleischer & Thomas Ray O Vac coat the lithium foil by cyanoacrylate

Yamin & Eichinger patented polymer and Acid in solution

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The Two Layers Model

7

Li

SEI 10-1000Å

Secondary

Layer

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Experimental

The Electrochemical cell

• Standard size AA/2 , AA ,D

• Surface area : 5 Cm2 , 14 Cm2 ,45 Cm2

• Bobbin type construction

• Electrolyte

- Reference cells LiAlCl4 ,standard electrolyte

- Test cells : standard electrolyte + additive

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Experimental

• Pulse test – Fast response Arbin data collecting system

• Electrochemical Impedance Spectroscopy - Solartron Sl 1260 impedance analyzer - typical 10mHz to 1MHz

• SEM study

- Specimens were prepared at dry room

- -40ºC due point

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Voltage Transient after 427 Days

R&D Cell

Reference XOL Cell

D size cells @ 100mA Pulse @ RT

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Voltage Transient after 180 Days

40mA pulse XOL electrolyte AA size cell

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Treated Lithium AA size XOL

40mA pulse 154 days old

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The Role of the new film

The new film separates between lithium and

SOCl2:

It prevents the vigorous reaction of SOCl2 with lithium metal :

- More ordered film is formed

- More dense and more compact SEI

- Less structural defects are formed by the slow reaction

2.0

2.2

2.4

2.6

2.8

3.0

3.2

3.4

3.6

0 10 20 30 40 50 60 70 80 90 100 110 120 130

V (

@1

ms)

t (Days from connecting the load)

OCV 360kΩ 180kΩ

Voltage after 1 mSec

Pulse test with background currents

20mA pulse for AA/2 Cell

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Additives decrease capacity variations

TL 7903 AA size XOL electrolyte @ 330 Ω

15% more capacity with the TMV improved cell

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Additives decrease capacity variations

TL 7903 AA size XOL electrolyte @ 680Ω

15% more capacity with the TMV improved cell

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Additives to Xtra Version cells

TL 8903 discharged @ 330 ohm Xtra

10 % more capacity than iXtra cell

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Additives to Xtra version AA cells

TL 8903 discharged @ 680 ohm

15% more capacity than iXtra cell

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Cell Types in Production

Tadiran Rapid Response Series TRR*

TRR 79XX – TMV improved XOL Type cells

AA size TRR 7903

D size TRR 7930

TRR 89XX – TMV improved Xtra type cells

AA size TRR 8903

D size TRR 8930

* Series Name Creator - Lou Adams

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Electrochemical Impedance Spectroscopy

Reference cells Test cells

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SEM Photograph 1M Old Cell

Reference cell

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SEM Photograph 1M Old Cell

Test Cells

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SEM Photograph 1 Y old Cell

Reference cell

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SEM photograph 1 Y old cell

Test Cell

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Summary & Conclusions

• Lithium anode was coated in situ by lithium ion conducting solid electrolyte interphase.

• The film morphology and cell impedance exhibit a small variation with storage time.

• This leads to a significant improvement of the voltage delay behavior of the Li/SOCl2 cells.

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Thank You