PEO-Based Composite Lithium Polymer Electrolyte

8/2/2019 PEO-Based Composite Lithium Polymer Electrolyte

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lonics 8 (2002) 79

PEO-based Composi te Li thium Polymer Electrolyte ,

PEO-BaTiO3-Li(C2FsSO~)~N

Q. Li* , N. Imanishi*, Y. Takeda*, A. Hirano* and O. Yam amoto**

* D e p a r t m e n t o f C h e m i s t r y , F a c u l t y o f E n g i n e e r i n g, M i e U n i v e r s it y , T s u , 5 1 4 - 8 5 0 7 , J a p a n

* * Gen es i s Resea rch In s t i tu t e , Nag o y a 4 5 1 -0 0 5 1 , Jap a n

A b s t r a c t . P o l y e t h y l e n e o x i d e ( P E O ) b a s e d p o l y m e r e l e c tr o l yt e s w i t h B a T i O 3 as f l l e r a nd

L i(C2F sSO2 )2 N as sa l t h av e b een ex amin ed in l i t h iu m p o ly me r b a t te r i e s . Th e a lu m in u m d i s-

so lu t io n po ten t ial in PEO-Li(C2FsSO2)2N wa s es t im ated to be 4 .1 V vs . Li /L i § at 80 ~ which

was co m p are d t o t h a t o f 3 .8 V v s . L i /L i + i n PEO-Li (CF ~SO2 )2 N. Th e e l ec t r ica l co n d u c t i v i t y o f t h esy s t e m wa s measu red as a fu n c t i o n o f O/L i r a t i o . Th e h ig h es t co n d u c t i v i t y was o b se rv ed i n

O/L i= 8 . Th e co n d u c t i v i t y was 1 .6 5 x 1 0 3 S / cm a t 8 0 ~ an d 1 .5 x 1 0 -5 S / cm a t 2 5 ~ Th e i n t e r-

f ac i a l r e s i s t an ce o f L i / p o ly m er e l ec t ro ly t e /L i an n ea l ed a t 8 0 ~ fo r 1 5 d ay s was l o w er t h an 1 0 0

~2 cm 2.

1 . Introduct ion

S i n c e p o l y e t h y l e n e o x id e ( P E O ) - ba s e d l i th i u m p o l y m e r

e l ec t ro ly t es were i n t ro d u ced i n li t h iu m seco n d ary b a t t e ri e s

i n t h e l a t e 1 9 7 0 s [1 ] , man y p o ly mer e l ec t ro ly t es h av e

b een d ev e lo p ed . S o m e p o ly me r e l ec t ro ly t es wi th a h ig h

co n d u c t i v i t y sh o w ed a p o o r mec h an i ca l p ro p er t i e s , an d th e

rev er se . A t p r esen t , P EO-b ased l i t h iu m co n d u c t i n g e l ec -

t ro ly tes hav e been found to be the be st candidate a s the

e l ec t ro ly t e i n l i t h iu m p o ly m er b a t t e r ie s i n v i ew o f t h e

e l ec t r ica l co n d u c t i v i t y an d t h e m ech an i ca l p ro p er t i e s . I n

th e p rev io u s p ap er s [2 ,3 ] , we h av e r ep o r t ed t h e e l ec t r i ca l

co n d u c t i v i t y o f t h e sy s t em , P EO -L iX- f i l l e r , an d o b se rv ed

that the composi te e lect ro ly te , PEO-Li(CF3SO2)2N-

BaTiO~ , sh o we d a h ig h co n d u c t i v i t y an d a l o w in te r f aci a l

r es i s t an ce wi th li t h iu m m eta l . T h e ad d i ti o n o f 1 0 we ig h t

% (wt% ) BaT iO 3 en h an ced t h e co n d u c t i v i t y an d imp ro v ed

th e s t ab i l it y w i th e l ec tro d e mate r i a l s . Ho w ev er , t h e a lu -

m in u m cu r r en t co l l ec to r , wh ich i s u sed wid e ly as a ca -

t h o d e cu r r en t co l l ec to r in l i t h iu m seco n d ary b a t t e r ie s ,

u n d erg o es se r i o u s co r ro s io n i n ca rb o n a t e -based e l ec t ro ly t e

so lu t ions con tain ing Li (CF3SO2)2N [4] . Recen t ly an al ter -

n a t i v e l i t h iu m sa l t w i th h ig h co r ro s io n r es i s t an ce fo r a l u -

min u m, b i sp e r f l u ro ro e th y l su l fo n in i i d e [L i (C2 F sS O2 )2 N] ,

h as b een p ro p o sed as a e l ec t ro ly t e in l i t h iu m b a t t e r i e s [5] .

Th i s l i t h iu m sa l t ex h ib i t ed a h ig h er d i s so lu t i o n v o l t ag e

com pared to Li(CF3SO2)2N in l iqu id elect ro ly te . In th is

s t u d y , th e e lec t r ica l co n d u c t i v i t y o f t h e co m p o s i t e e l ec -

t ro ly te , P EO-L i (C2 F sS O2 )2 N-B aTiO 3 an d t h e r eac t i v i t y o f

t h e e l ec t ro ly t e wi th l i t h iu m meta l an d t h e ca th o d e ac t i v e

mate r i a l o f L iNi0 8 Co ~2 0 2 as we l l a s t h e a lu m in u m d i s -

so lu t i o n p o t en t i a l i n to t h e co mp o s i t e e l ec t ro ly t e a t a h ig h

t emp era tu re h av e b een ex amin ed .

2 . Ex per i m en ta l D es cr i p t i o n

T h e P E O - b a s e d c o m p o s i t e p o l y m e r e l e c t ro l y t e w e r e o b -

t a in ed b y a so lv en t cas t i n g t ech n iq u e u s in g ace to n i t r il

( A N ) a s a c a r r i e r s o l v e n t [6 ]. H i g h m o l e c u l a r w e i g h t P E O

(Ald r ich Ch em ica l , 6 x 1 0 5 av erag e mo lecu l a r we ig h t ) ,

Li (CF3SO2)2N (Fu lka Ch em ical ) , Li (C2FsSO2)2N (3M)

were u sed as rece ived . Bar iu m t i t an a te (S ak a i Ch e mic a l s ,

0 .5 ~tm and 0 . I ~ t avera ge par t ic le s ize) wa s dr ied under

v ac u u m a t 1 0 0 -1 5 0 ~ fo r 2 4 h . P rep ara t i o n o f th e co m -

p o s i t e e l ec t ro ly t es i n v o lv ed t h e d i sp e r s io n o f t h e B aT iO 3

p o w d er an d l i t h iu m sa l t in AN, t h en fo l l o we d t h e ad d i t io n

o f P E O . T h e s l u rr y w a s c o m p l e t e l y h o m o g e n i z e d a n d

th en cas t o n to a f l a t p o ly t e t r a f lu ro ro e th l en e v e sse l . Th e

so lv en t i n t h e s l u r ry was a l l o wed t o ev ap o ra t e s l o wly

u n d er t h e f l o w o f n i t ro g en g as fo r 2 4 h a t r o o m t em-

p e r a tu r e . F i n a ll y t h e c o m p o s i t e p o l y m e r e l e c t r o l y te f i l m s

were d ri ed a t 6 0 -9 5 ~ u n d er v ac u u m fo r 4 8 h . Th ese



80 l on i c s 8 (2002)

p r o c e d u r e s y i e l d m e c h a n i c a l l y s t a b l e m e m b r a n e s w i t h a n

a v e r a g e t h i c k n e s s o f a b o u t 3 0 0 / a m .

T h e a l u m i n u m d i s s o l u t io n p o t e n t ia l w a s e s ti m a te d

w i t h t he h e l p o f c y c l ic v o l t a m m o g r a m s i n t h e c el l

L i / P E O - L i X - 1 0 w t % B a T i O f l A l a t 8 0 ~ w h e r e a S o l a -

t r o n 1 2 8 7 p o t e n t i o s t a t w a s r u n a t a s c a n r a t e o f 1 0 m V /

s e c a n d t h e d i s s o l u t i o n p o t e n t i a l w a s d e t e r m i n e d a t a

c o r r o s i o n c u r r e n t o f 5 l a A / c m 2. T h e e l e c t ri c a l c o n d u c t i v i t y

o f th e c o m p o s i t e p o l y m e r e l e c t r o l y t e a n d t h e i n te r fa c i al

r e s i s ta n c e b e t w e e n t h e e l e c tr o l y t e a n d t h e l i t h i u m a n o d e

[o r t he c om po s i t e ca thod e o f L iN i0. sC o0 .202 , e l ec t ro ly t e

a n d a c e t y l e n e b l a c k ( 6 5 : 2 0 : 1 5 w t r a ti o ) ] w e r e m e a s u r e d b y

a c i m p e d a n c e m e t h o d u s i n g S o l a t r o n 1 2 6 0 fr e q u en c y

a n a l y z e r . S t a i n l e s s s t ee l b l o c k i n g e l e c t r o d e c e l l s w e r e u s e d

f o r c o n d u c t i v i t y m e a s u r e m e n t s , a n d s y m m e t r i c a l n o n -

b l o c k i n g l i t h i u m ( o r t h e c a th o d e c o m p o s i t e e l ec t ro d e )

c e l l s w e r e u s e d t o i n v e s t i g a t e i n t e rf a c i a l p h e n o m e n a . A 1 0

m V a c a m p l i t u d e w a s a p p l i e d a n d th e d a t a w e r e c o ll e c te d

b y r e c o r d i n g t e n p o i n t s p e r d e c a d e o v e r a f r e q u e n c y r an g e

f r o m 1 H z t o 1 M H z i n c o n d u c t i v i ty m e a s u r e m e n t s , a nd

f i o m 0 . 0 5 H z t o 1 0 k H z i n i n te r r ac i a l r e s i st a n c e m e a -

s u r e m e n t s .

3 . R e s u l t s a n d D i s c u s s i o n

P r e v i o u s l y r e p o r t e d l i t h i u m p o l y m e r e l e c t r o l y t e c e l ls c o n -

s i s te d o f li t h i u m a n o d e a n d 3 V c l a s s c a t h o d e m a t e ri a ls

s u c h a s v a n a d i u m o x i d e s [ 7 ]. A l u m i n u m d i s so l v e d in t oL i ( C F 3 S O 2 ) 2 N c o n t a i n i n g p r o p y l e n e c a r b o n a t e s o l u t i o n

a rou nd 4 V vs . L i /L i § [4 ] . I n 3 V c l a s s ce l l s , t he r e fo re , t he

c o r r o s i o n o f a l u m i n u m c u r r e n t c o l le c t o r s h as n o p r o b l e m .

4 V c l a s s l i t h i u m c e l l s m e e t w i t h a c o r r o s i o n p r o b l e m o f

a l u m i n u m w h e n L i( C F 3 S O 2 ) 2 N w a s u s e d i n t h e e l e c tr o -

l y te . T a b l e 1 s h o w s t h e a l u m i n u m d is s o l u ti o n v o l t a g e

a l o n g w i t h t h e A 1 / c o m p o s i t e c a t h o d e c o n t a c t r e s i s t a n c e s

Table I . A lum inum dissolut ion potent ia l of PEO-LiX and the

con t ac t r e si s tance be tw een a lum inum and C om pos i t e ca thode :

[LiNi0.sCo0~O, -PEO~(C2FsSO:)2N-acetylene black (70:15:15

weight ra t io) ] .

LiX

A l

d i s s o l u t i o n

P o t e n t i a l

vs. Li/Li § V

LiX free

Li(CF3SO)2N 3.8

Li(C.FsSO,)2N 4. I

Contact res is tance f2cm:

Pt AI A1

(99.999'0) foil

2 2

2 5 0 8 0

2 20 55

"7

Eo

ra~

~,d.ae.)

Or,.)

10"3

10 4

""tu s -- 0 -1 9 /

1 0 4 ~ s - O - 2 " ~

- - 0 - 4

1 ! !

3 .5 3. 6

I O 0 0 / T [ K "1]Fig. 1 . The Arrhenius p lots fo r the comp osi te po lym er

PEO~Li(C2F~SO,),N- 10wt%BaTiO~ as a fu nction o f O/Li.

~E

o

.B

0

a t 8 0 ~ T h e a lu m i n u m d i s s o l u ti o n v o l ta g e w a s es t i-

m a t e d t o b e 3 . 8 V v s . L i / L i § a t 8 0 ~ A s e x p e c t e d ,

P E O - L i (C 2 F s S O _ ,) 2 N s h o w e d m o r e h i g h e r a l u m i n u m d i s-

s o l u t i o n v o l t a g e o f 4 . 1 V v s . L i / L i + . T h i s h i g h d i s-

so lu t i o n vo l t ag e i s qu i t e a t t r ac t i ve [' o r t he l i t h ium po ly -

m e r b a tt e r ie s , b e c a u s e w e h a v e p o s s i b i l i t y t o u s e t h e c a -

t h o d e a c t i v e m a t e ri a l s w i t h h i g h c e l l v o l t a g e s u c h a s

L i C o O 2 a n d L i N i O : [ 1 0 ]. T h e c o n t a c t r e s is t an c e o f A I /c o m p o s i t e c a t h o d e r e a c h e d 8 0 f 2c m -" a f t e r a n n e a l i n g a t 8 0

~ f o r 5 5 0 h . T h e c o n t a c t r e s i s ta n c e o f A l / c o m p o s i t e

c a t h o d e c o n t a i n i n g L i (C 2 F s S O 2 )2 N w a s l o w e r t h a n t h a t o f

10-~ ,, ,

, e X

10"

1 0 s

10 4

1 0 a

10"*

2 5 ~

50*C

._ A - soOc

t

' ', ; ' , ; . . . . . . . u6 1 1 20 30 S S 40 46 50

O:L i ratio

Fig . 2. Con duct ivi ty i sothermal of PEO-Li(C2FsSOz)2N-

10wt% BaTiO 3 as a function of O /Li .



I on i c s 8 ( 2002 ) 81

T a b l e 2 . E l e c tr i c a l c ondu c t i v i t y a nd l i th i um i on t r a ns f e re nc e

Li(C2F~SO~.)zN]-10wt%BaTiO3.

num be r i n [ P E O x -

C on duc t i v i t y ( S / c m ) T r a ns f e r e nc e

C o m p o s i t i o n N u m b e r ( 80 ~

80 ~ 25 ~

PEO~-Li(C2FsSO2)2N- O/Li

10wt%BaTiO~(0.5 I . tm)

5 0 0 . 4 5 • .3 0.5X I0 "6 0 . 1 6

1 5 0 . 7 1 4 . 0 0 . 1 3

1 2 1 . 0 l 8 . 0 0 . 1 0

8 1 . 65 15 0 . 0 7

4 0 . 7 6 5 . 5 0 . 0 5

PEOlzLi(C~.F~SO~)2N- BaTiO~wt%

XB aTiO 3 (0 .5 l ain)

1 5 0 . 8 6 x l 0 ~ 5 . 2 6 x 1 0 -6 0 . 0 7

1 0 1 . 2 4 6 . 5 3 0 . 0 8

5 1 .4 6 7 . 7 5 0 . 0 9

1 1 . 1 5 7 . 6 7 0 . 1 0

0 0 . 9 2 7 . 4 7 0 . I 0

PEOI2Li(C2FsSO2)2N- Siz e of

5wt%BaTiO3 BaTiO3(lam

0 . 1 1 . 15 x10 -3 4 . 8 4x 10 "6 0 . 11

0 . 5 1 . 4 6 7 . 7 5 0 . 0 9

PEOtgLi(CF3SO2)2N 1.7• 10 -3 7 .9 • 10 -6 0 .1 3

10wt%BaTiO3(0.5 lam)

PE O L~Li(CF3SO2)2N- 8 • l 0 .4 10• 10 6

10wt%BaTiO3(0.5 ~tm)

L i (C F 3 S O 2 ) R N . T h i s r e s is t a n c e m a y b e d u e t o f o r m a t i o n

o f a n in t e rf a c e l a y e r o n a l u m i n u m w i t h h i g h r e s is t a n ce .

I t i s e x p e c t e d t h a t a l u m i n u m w i l l t h e r m o d y n a m i c a l l y

c o r r o d e d u r i n g c h a r g i n g a n d d i s c h a r g i n g b e c a u s e t h e s t a n d -

a r d el e c t r o d e p o t e n t i a l o f a l u m i n u m ( 1 .3 9 V v s . L i / L i § i s

m u c h l o w e r t h a n th e n o r m a l p o t e n t i a l o f t h e p o s i t i v e

e l e c t r o d e i n t h e l i th i u m b a t t e ri e s . H o w e v e r , a l u m i n u m i s

k i n e t i c a l l y s t a b l e in m a n y c i r c u m s t a n c e s b e c a u s e i t i s

c o v e r e d w i t h a p a s s i v e f i l m . T h e c h a r a c t e r i s t i c s o f t h e

p a s s i v e f i l m i n t h e l i t h i u m b a t t e r i e s d e p e n d o n t h e c a -

t h o d e c o m p o s i t e , m a i n l y , o n t h e e l e c tr o l y t e s a l t i n t h e

c a th o d e c o m p o s i t e. T h e h i g h a l u m i n u m d i s s o lu t i o n p o -

t e n t i al o f P E O - L i ( C 2 F s S O 2 ) 2 N m a y b e d u e t o t h e f o r -

m a t i o n o f a f i l m o n a l u m i n u m . H o w e v e r , i t i s n o t s u r e

y e t w h a t k in d o f f i lm w a s f o r m e d o n a l u m i n u m .

A p o l y m e r e l e ct r o ly t e s h o u l d h a v e a h i g h l i t h iu m i o n

c o n d u c t i v i t y t o o b t a i n h i g h p e r f o r m a n c e p o l y m e r b a t te -

r i es . A n a c c e p t ab l e c o n d u c t i v i t y v a l u e is 1 0 3 S / c m a t

o p e r a t i n g t e m p e r a t u re , w h i c h i s c o m p a r a b l e t o t h e c o n -

d u c t i v i t y in l i q u i d l it h i u m i o n c o n d u c t i v e e l e c t r o l y t e w i t h

a p o r o u s s e p a r at o r . T h e h i g h e l e c tr i c a l c o n d u c t i v i t y r e-

d u c e s t h e e le c t r o l y t e r e s i s t a n c e a n d a l s o e l e c t r o d e r e a c t i o n

r e s i s t a n c e . T h e t e m p e r a t u r e d e p e n d e n c e s o f t h e e l e c t r ic a l

c o n d u c t i v i t y o f th e P E O - L i (C 2 F s S O 2 ) 2 N - B a T iO 3 s y s t e m

a r e s h o w n a s a fu n c t i o n o f a O / L i r a t i o i n F i g . 1 a n d t h e

c o n d u c t i v i t y i so t h e r m s o f th e s y s t e m i n F i g . 2 . T h e

h i g h e s t c o n d u c t i v i t y i s o b s e r v e d i n O / L i = 8 a t a ll t h e

t e m p e r a t u r e s o b s e r v e d . T h e c o n d u c t i v i t y o f t h e p o l y m e r



82 l on i c s 8 (2002)

e l ec t r o ly t e i s o f t en e xp l a ined i n t e rm o f t he t r ade-o f f be t -

w e e n i n c r e a s i n g n u m b e r o f c h a r g e c a r r i e r s a n d i o n m i g r a -

t i o n a n d i n c r e a s e d v i s c o s i t y d u e t o i o n i c c r o s s - l i n k i n g .

T h e A r r h e n i u s p l o t s i n F i g . 1 s h o w e d a c u r v a t u r e at 4 0 -

6 0 ~ P E O - L i ( C e F s S O 2 ) 2 N s y s t e m t e n d t o m e l t a t a

t e m p e r a t u r e a r o u n d 5 0 - 6 0 ~ T h e m e l t i n g p o i n t s d e pe n d

o n t h e s a l t c o n c e n t r a t i o n . T h e t e m p e r a t u r e s o f th e c u r v a -

t u r e c o r r e s p o n d t o t he p h a s e t r a n s i t i o n t e m p e r a t u r e . T h e

a c t i v a t i o n e n e r g y f o r c o n d u c t i o n i n a h i g h t e m p e r at u r e

r a n g e i s l o w e r t h a n t h a t i n a l o w e r t e m p e r a t u r e r a n g e . I n

t h e h i g h te m p e r a t u r e r a n g e , t h e c o n d u c t i o n i s d u e t o l o w

v i s c o u s m e l t p h a s e a n d i n th e l o w e r t e m p e r a t u re d u e t o

h i g h v i s c o u s g l a s s y p h a s e .

T h e e l e c t ri c a l c o n d u c t i v i t y o f P E O - L i ( C 2 F s S O e ) 2 N -

B aT iO 3 s y s t e m d e p e n d e d o n t h e c o n t e n t o f B aT iO ~ a n d t h e

p a r t i c l e s iz e . T h e c o n d u c t i v i t i e s a n d t h e l i th i u m i o n t r a n s -

f e re n c e n u m b e r s o f th i s s y s t e m a r e s u m m a r i z e d i n T a b l e

2 . T h e t ra n s f e r e n ce n u m b e r w a s m e a s u r e d b y t w o i m p e -

d a n c e - p o l a r i z a t i o n c o u p l i n g t e c h n i q u e s [ 9 ] . T h e c o n d u c -

t i v i ty i n t h e P E O - L i ( C e F s S O , ) 2 N - B a T i O 3 s y s t e m i s c o m -

pa rab l e t o t ha t i n t he PEO -Li (C F3SO 2)~ _N -sys t em . The

r o o m te m p e r a t u r e c o n d u c t i v i t y o f 1 . 5 • -5 S / c m i n

P E O s L i ( C , F s S O 2 ) e N - 1 0 w t % B a T i O 3 is s l i g h t l y h i g h e r

t h a n t h a t i n P E O - L i ( C F ~ S O _ ,) 2 N - B a T iO 3 . T h e l i t h i u m i o n

t r a n s f e r e n c e n u m b e r i n P E O - L i ( C 2 F s S O 2 ) 2 N - B a T i O ~ i s

a r o u n d 0 . 1 , w h i c h is c o m p a r a b l e t o t h a t i n P E O -

L i ( C F ~ S O e ) : N - B a T i O . T h e t o t a l c o n d u c t i v i t y i n t h i ssys t em inc reased and the t r ans f e r en ce nu m b er dec reased

w i t h d e c re a s i n g t h e O / L i . T h e l i t h i u m i o n c o n d u c t i v i t y

w a s a l m o s t c o n s t a n t i n th e r a n g e o f O / L i = 15 -8 .

A n a n o t h e r i m p o r t a n t p a r a m e t e r i n c h a r a c t e r i z a t i o n

o f a g i v e n p o l y m e r e l e c t r o l y t e is t h e e l e c t r o c h e m i c a l

0 . 0 0 0 1 5

^ 0 . 0 0 0 1

0.00005

I

0 3

l : '

: i

I

4 5 6

C e l l V o l l n g e / V

Fig. 3 . Linear sweep vol tam metry of s ta inless s tee l / PEO-Li(C2F.~SO_,):N-10wt%BaT iOJLi at 80 ~ Sweep rate: 0.1

mV/sec. O:Li = a: 15, b: 12. c: 8, d: 19, e: 50.

s t a b i l i t y w i n d o w . T h e s t a b i l i t y w i n d o w w a s e v a l u a t e d b y

l i n e a r s w e e p v o l t a m m e t r y u s i n g s t a i n l e s s s t e el a s

w o r k i n g e l e c t ro d e a n d l i t h i u m f i l m a s c o u n t e r e l e ct r o de .

F i g u r e 3 s h o w s t y p i c a l v o l t a m m e t r y r e s u l t s f o r

P E O , L i ( C ~ F s S O 2 ) 2 N - 1 0 w t % B a T i O ~ a t 8 0 ' C . W e n o t i c e

t h a t t h e s w e e p m a y b e e x t e n d e d t o o v e r 4 V v s L i / L i + i n

t h e a n o d e r e g i o n b e f o r e o b s e r v i n g a p p r e c i a b l e c u n ' e n t ,

w he re t he sw e ep r a t e w as 0 ,1 m V /sec . I t is a l i t tl e d i f fi -

c u l t t o e s t i m a t e t h e e x a c t d e c o m p o s i t i o n p o t e n t i a l b y t h i s

m e t h o d . H o w e v e r , w e c a n s a y th a t t h i s s y s t e m c o u l d b e

used i n 4 V c l a s s l i t h ium ba t t e r i e s .

Th e s t ab i l i t y o f t he e l ec t ro ly t e / e l ec t rode i n t e r f ace i s

o n e o f t h e m o s t i m p o r t a n t p a r a m e t e r s i n t e r m s o f b a t t e r y

c y c l a b i l i t y a n d s t o r a g e . I n t h e p r e v i o u s p a p e r [ 6 ] , w e

repor t ed t he i n t e r f ac ia l r e s i s t ance be tw een l i t h ium anode

a n d P E O - L i X - B a T i O ~ . T h e i n t e r f a c e r e s i s t a n c e d e p e n d e d

on t he p rope r t i e s o f l i t h ium sa l t s . Th e i n t e r f ac i a l r e-

s i s t ance be tw een l i t h ium m e ta l and PEO jgLi(C F. ~SO 2)_~ N -

1 0 w t % B a T i O 3 w a s a s l o w a s 6 7 f 2 c m -~ a f t e r c o n t a c t i n g 8 0

~ fo r 30 days . h t con t r a s t , t he i n t e r f ac i a l r e s i s t ance

b e t w e e n l it h i u m m e t a l an d P E O s L i C I O 4 w a s a s h i g h a s

1020 f2c m -~ a f t e r con t ac t i ng a t 70 '~ C lb r 25 days . A l s o ,

t he i n t e r f ac ia l re s i s t ance be tw ee n a ca tho de m a te r i a l an d a

p o l y m e r e l e c t r o l y t e w a s e x a m i n e d b y L i e t al . [ 8 ] . T h a t

o f P E O I 9 L i (C F 3 S O 2 ) :N 1 0 w t % ~ f f i O J c a t h o d e m i x t u r e

(L iN i , . sC o0 . 202 , po lym er e l ec t ro ly t e , and ace ty l ene b l ack )

w a s a ro u n d 2 0 cm - ' a f te r c o n t a c t i n g a t 8 0 ~ f o r 4 0 0 h .The i n t e r f ac i a l r e s i s t ance be tw een t he ca thode m a te r i a l s

and t he e l ec t ro ly t e show ed no no t ab l e d i f f e r ence on t he

l i t h i u m s a l ts in P E O . F i g u r e 4 s h o w s t h e t i m e

dependence o f t he i n t e rf ac i a l r e s i s t ance o f t he ce l l , L i / (o r

c a t h o d e m i x t u r e ) / PEO,Li(C2FsSO:)2N-IOwt%BaTiOJLi

(o r t he ca thode m ix tu re ) , annea l ed a t 80 ~ w he re t he

ac t i ve e lec t rode a r ea w as 0 . 5 cm 2 . Th e ca thode m ix tu re

c o n s i s t e d o f L i N i 0 ., C o ,, ~ O 2 , P E O ~ L i ( C 2 F s S O 2 ) : N -

1 0 w t % B a T iO 3 , a n d a c e t y l e n e b l a c k ( 7 0 : 1 5 : 1 5 w e i g h t

r a t i o ) . T h e i n t e r f a c i a l r e s i s t a n c e s b e t w e e n t h e p o l y m e r

e l e c t r o ly t e a n d l i th i u t n m e t a l ( o r c a th o d e m i x t u r e ) w e r e

c o m p a r a b l e t o t h at o f P E O , L i (C F ~ S O , ) z N - 1 0 w t % B a T i O 3 .

T h e l o w i n te r f ac i a l r e si s t a n c e b e t w e e n e l e c t r o l y t e a n d

e l e c t ro d e m a t e ri a ls p r o v i d e s a n e x c e l l e n t p o l y m e r l i t h i u m

s e c o n d a r y . T h e l i t h i u m s e c o n d a r y c e l l s w i t h

P E O ~ z L i ( C 2 F s S O 2 ) 2 N - 1 0 w t % B a T i O : a s t h e e l e c t r o ly t e ,

l i t h iu m m e t a l a s t h e a n o d e , a n d t h e m i x t u r e o f

L iN i . . sC o~ . ~ O _ , , po lym er e l ec t ro ly t e , and ace ty l ene b l ack

( 6 5 : 2 0 : 1 5 w t % ) a s t h e c a t h o d e w e r e e x a m i n e d . I n F i g 5 , a

t y p i c a l c h a r g e r a n d d i s c h a r g e c y c l i c p e r f o r m a n c e a t 8 0 ~

i s show n , w he re t he ce l l w as cha r , , ed up t o 3 . 9 V and



I o n i c s 8 ( 2 0 0 2 ) 8 3

S O 0

4 0 0

3O O

2O O

1 0 0

( a )

- - I I - - O :L i 12

~ - - - O : L i 15

~ - - - O : L i 1 9

I

0 1 0 0 2 0 0 3 0 0

Tim e Oa)

4 0 0

8

t 4 0

1 3 0

1 2 0

1 1 0

t 0 0

9 0

8 0

7' 0

6 0

5 0

4 0

3 0

2 0

--O --- 2 .5-3.9V charge

3.9-2.5V discharge

; 1 ; ;0 30 6 5 ; 6 ; 7 ;

C y c l e n u m b e r

3 0 0

2 6 0

8 2 0 0

~ , 1 6 0

1 0 0

60

(b)

- m - O : L I 1 9

~ o:t,i 8

0 1 0 0 2 0 0 3 0 0 4 0 0

T i m e ( h )

F i g . 4 . T i m e c h a n g e a t 8 0 ~ o f t h e i n t e r f a c i a l

res is tance in L i /PEO~(C2F~SO2)zN-I0wt%BaTiO 2 (a ) and inc a t h o d e c o m p o s i t e / P E O ~ ( C ~ F s S O : ) : N - 1 0 w t % B a T i O 3 ( b ). C a -

thode compos i te : L iNi08Co0202-PEOx(C2FsSO, )zN-ace ty leneb l a c k ( 7 0 : 1 5 : 1 5 w e i g h t r a t i o ) .

d i s c h a r g e d t o 2 .5 V . T h e i n i t i a l c a t h o d e c a p a c i t y o f 1 15

m A h / g o f L i N i o s C o 0 .2 0 2 w a s o b t a i n e d , t h e v a l u e o f

w h i c h w a s c o m p a r a b l e t o t h a t o b t a i n e d i n t h e c e l l

w i t h l i qu i d e l e c t r o l y t e , 1 2 0 m A h / g . T h e c e l l s h o w s a

g o o d c y c l i n g p e r f o r m a n c e . T h e c a p a c i t y f a d i n g b y

c y c l i n g w a s a b o u t 0 . 3 5 % / c y c l e , w h i c h w a s c o m p a r e d t o

0 . 6 % / c y l c e in th e c e l l , L i / P E O 2 o L i S O s C F s - T L i A 1 0 2 /

L i M n z O 4 [ 10 ].

F ig . 5 . Cyc l ic pe r fo rmance o f L i /PEO~zLi(C2FsSO,_)_~N-

1 0 w t % B a T i O 3 /c a th o d e c o m p o s i t e a t 8 0 ~ C a t h o d e c o m -p o s i t e : L i N i 0 . s C % O:-PEO~zLi(C_~F~SO_0zN-1 0 w t % B a T i O ~( 7 0 : 1 5 : 1 5 w e i g h t r a t i o ) , c h a r g e an d d i s c h a r g e c u r r e n t d e n -s i t y : 0 . 2 m A / c m 2.

4 . C o n c l u s i o n

T h e P E O b a s e d p o l y m e r e le c t r o ly t e s w i t h Li(C2FsSO2)2N

a s t h e s a l t h a v e b e e n e x a m i n e d a s t h e e l e c t r o l y t e i n

l i t h i u m p o l y m e r b a tt e r ie s . T h i s e l e c t r o l y t e s h o w s t h eh i g h a l u m i n u m c o r r o s i o n p o t e n t i a l o f 4 .1 V v s . L i / L i + a t

8 0 ~ a n d t h e h i g h e l e c t r i c a l c o n d u c t i v i t y o f 1 . 6 5 x 1 0 -3

S / c m a t 8 0 ~ a n d 1 . 5 x 1 0 5 S / c m a t 2 5 ~ T h e a d d it i on

o f B a T i O 3 c e r a m i c s e n h a n c e t h e e l e c tr i c a l c o n d u c t i v i t y o f

e l e c t r o l y te as w e l l a s m e c h a n i c a l s t r e n g t h . N o s i g n i f i c a n t

c a p a c i t y f a d e u p o n c y c l i n g i n L i / P E O ~ 2 L i ( C 2 F s S O 2 ) 2 N -

B a T i O f f L i N i o . 8 C o o . 2 0 2 i s o b s e r v e d u p o n c h a r g i n g u p t o

3 . 9 V a t 8 0 ~

5 . A c k n o w l e d g e m e n t s

T h i s w o r k w a s c a r r i e d o u t u n d e r a c o l l a b o r a t i o n p r o g r a m

b e t w e e n M i e U n i v e r s i t y a n d G e n e s i s R e s e a r c h I n s t i t u t e .

I n c .

6 . R e f e r e n c e s

[ I ] M . B . A r m a n d , J . M . C h o q u e t t e a n d M . D u c l o t , i n :

E x t e n d A b s t r a c t s , 2 n d I n t e r n a t i o n a l M e e t i n g o n

S o l i d E l e c tr o l y t e s , S t A n d r e w s , S c o t l a n d ( 1 9 7 8 ) .

[ 2] H . Y . S u n , H . - J . S o h n , O . Y a m a m o t o , Y . T a k e da ,

a n d N . I m a n i s h i , J . E l e c t r o c h e m . S o c . 1 4 6 , 1 6 7 2

( 1 9 9 9 ) .



84 lonics 8 (2002)

[ 3] H .Y . Sun , Y . Takeda , N . I manish i . O . Y am amoto

and H . - J . Sohn , J . E lec t r ochem. Soc . 14 7 , 2462

(2000) .

[ 4] H . Y ang, K . K w on , T .M. D evine and J .W. Evans ,

J . E lec t r ochem. Soc . 147 , 4399 ( 2000) .

[ 5] S .D . B oyd, B . J . John son , L . J . K r aus , W.M .

Lam anna , P .T . Ph am and H . Shimada , 10 th I n ter -

na t iona l Mee t ing on L i th ium Ba t te r ie s , A bs t r ac t

N o. 278 . Como, I t a ly ( 2000) .

[6] Q. Li , H.Y. Sun. Y. Takeda, N. Imanishi , J . Yang

a n d O . Y a m a m o t o , J. P o w e r S o u r c e s 9 4 , 2 01

(2001 ).

[7] M. Gsu thier . M. Armand and L. Krause, 7th

I n te r na t iona l Mee t ing on L i th ium Ba t te rie s , Ex t .

A bs t r ac t , Bos ton , U SA , 1994, P . 177 .

[8] Q. Li , Y. Tak eda, N. Imanishi , J . Yang. H.Y. S un

a n d O . Y a m a m o t o , J . P o w e r S o u r c e s 9 7 / 9 8 , 7 9 5

(200 I ) .

[ 9] J . Evanc e , C .A . V incen t and P .G . Br uce , Poly mer

28 , 2324 ( 1987) .

[ 10] G .B. A ppe tecchi , F . G r oce , M. Ma s t r ogos t ino , B .

Scrosat i , E. Soavi and A. Zanell i , J . Electrochem.

Soc . 145 , 4133 ( 1998) .

P a p e r p r e s e n t e d a t t h e 8 t h E u r o C o n f e r e n c e o n l o n i c s ,

C a r v o e i r o , A l g a n ' e , P o r t u g a l , S e p t . 1 6 - 2 2 , 2 0 0 1 .

M a nusc r ip t rec . Sep t . 17 , 2001; r ev . Jan . 2 . 2002 ; acc .

Jan . 15 , 2002 .

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