gas evol pb b submarine

8/3/2019 Gas Evol Pb B Submarine

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E L S E V I E R J o u r n a l o f P o w e r S o u r c es 5 3 ( 1 9 95 ) 9 % 1 0 7

G a s e v o l u t i o n a n d p e r f o r m a n c e a s s e s s m e n t o f s u b m a r i n el e a d / a c i d b a t t e r i e s

J . B . L a k e m a n 1DR A We s t Dra y t o n , K i n g s to n La n e , We s t Dra yt on , Mi d d x . U B7 9 QB, UK

Received 22 Aug ust 1994; accepted 9 September 1994

A b s t r a c tTh e g as -ev o lu t i o n r a t es f ro m n ew an d en d -o f - l i f e l ead / ac id su b mar in e ce l l s a t b o th o p en -c i r cu i t an d u n d er f l o a t - ch arg e h av e

b een ex amin ed , t o g e th er wi th t h e d i sch arg e p e r fo rm an ce o f t h e ce ll s. Th e ev o lv ed g as i s f o u n d t o co m p r i se h y d ro g en an do x y g en o n ly . Th e o p en -c i r cu i t an d f l o a t - ch arg e h y d ro g en -ev o lu t i o n r a t es v a ry lo g ar i th mica l l y wi th t em p era tu re . Th e en th a lp yof act ivat ion for open -ci rcu i t hydrog en evolu t ion i s ~ 70 kJ mo1-1 for bo th o ld and new cel ls . The op en-ci rcu i t hydrogen-ev o lu t io n r a t e p e r A h o f r a t ed ca p ac i t y fo r n ew ce l l s is b e tween 0 .0 0 63 6 an d 0 .1 0 5 cm3 h -1 Al l -1 at STP at 20-50 C,respect ively . Fo r o ld cell s , a > th ree-fo ld increas e i s obse rved , the evo lu t ion rate range s f rom 0 .0237 to 0 .361 cm 3 h - 1 A h - 1a t S T P a t 2 0 -5 0 C , r esp ec ti v e ly . On f l o a t - ch arg e , u s in g an u n co mp en sa t ed f l o a t v o l t ag e , t h e h y d ro g en -ev o lu t i o n r a t e o f n ewcel ls i s betw een 0 .0166 and 0 .241 cm 3 h-~ Ah -~ at S TP a t 20-50 C, respect ively . For o ld cel ls , the r ates inc rease to 0 .0298--0 .903cm 3 h - I A h - I a t S TP a t 2 0 -5 0 C , resp ec t iv e ly . I n co n t r as t , t h e e l ec t ri ca l d i sch arg e p e r fo rm an ce o f t h e ce l l s d ec reases wi thag e . Th i s su g g es ts t h a t t h e ac t iv e a r ea fo r h y d ro g en ev o lu t io n i n c reases wi th ag e , b u t t h a t t h e ac t i ve a r ea fo r e l ec t r ica l d i sch arg ed ecreases . No co r r e l a t i o n h as b e en es t ab l i sh ed b e tween h y d ro g en ev o lu t i o n in i n d iv id u al ce l ls an d e l ec t ri ca l d i sch arg e p e r fo rm an cefo r ce l l s o f t h e same ag e . Th e se l f -d i sch arg e r a t es o f t h e n eg a t i v e p l a t es a t 2 0 C a re 1 4 an d 5 0 % p er y ear fo r n ew an d o ldcells, respectively.Keywords: Open-circuit; Float-charge; Ga s evolution; Self-discharge; Lead/acid batteries; S ubma rines

1 . I n t r o d u c t i o n g a s e v o l u t i o n c a n p o s e a s e r i o u s t h r e a t t o v e h i c l e s a f e t y ,a n d m u s t b e k e p t t o a m i n i m u m w h e n t h e v e h i c le is

O n - c h a r g e g a s e v o l u ti o n , a n d t h e a s s o c i a t e d c h a r g i n g s u b m e r g e d . I t is , t h e r e f o r e , o f c r it ic a l i m p o r t a n c e t h a te f f ic i e n c y o f l e a d / a c i d c e l ls , c a n b e u s e d a s a n i n d i c a t o r t h e r a t e o f h y d r o g e n e v o l u t i o n , p a r t i c u l a r l y , i s k n o w no f c e l l c o n d i t i o n . T h e g a s e v o l v e d d e r i v e s l a r g e l y f r o m a t a ll s t a g e s o f t h e s u b m a r i n e b a t t e r y d u t y c yc l e , i nt h e e l e c tr o ly s i s o f w a t e r o n o v e r c h a r g e , w i t h t h e c o m - o r d e r t h a t a d e q u a t e g a s - m a n a g e m e n t s y s t e m s c a n b ep o n e n t s h y d r o g e n a n d o x y g e n p r o d u c e d in a f a ir ly d e s i g n e d a n d i m p l e m e n t e d .c o n s t a n t r a t i o [ 1] . L o w e v o l u t i o n o f g a s i s a s s o c i a t e d T h e i n c r e a s e d u s a g e o f v a l v e - r e g u l a t e d l e a d / a c i dw i t h b e t t e r c h a r g e r e t e n t i o n a n d l o w e r m a i n t e n a n c e b a t t e r i e s ( V R L A ) h a s a l so h i g h li g h te d t h e n e e d t o( t o p p i n g u p ) [2 ]. O n o p e n - c i r c u i t , h y d r o g e n e v o l u t i o n m i n i m i z e g a s e v o l u t i o n , a n d a g r e a t d e a l o f r e s e a r c hi s a s s o c i a t e d w i t h s e l f - d i s c h a r g e o f t h e n e g a t i v e p l a t e , h a s a l r e a d y b e e n c o n d u c t e d ( s e e , f o r e x a m p l e , R e f s .a n d o x y g e n w i t h t h e p o s it iv e . T h e r e f o r e , t h e c o m p o s i t i o n [ 3 -6 ] ). T h e d a t a o b t a i n e d o n v e r y l a r ge s u b m a r i n e c e ll so f t h e e v o l v e d g a s c o u l d v a r y. O n f l oa t - c h a r g e , i t c a n c a n b e e x t r a p o l a t e d b a c k t o gi ve m o r e a c c u r a t e i n -b e a s s u m e d t h a t t h e e v o l v e d g a s w i ll d e r i v e b o t h f r o m f o r m a t i o n a b o u t m u c h s m a l l e r s y s te m s , f o r w h i c h p r e c i s es e l f- d i s c ha r g e m e c h a n i s m s a n d f r o m t h e e le c t ro l y si s o f d a t a f o r g a s e v o l u ti o n o n o p e n - c i r c u i t a n d f l o a t- c h a r g e ,w a t e r , a r e n o t a v a i la b l e b e c a u s e o f t h e s m a l l a m o u n t s o f g a s

I n w e l l - v e n t i l a t e d e n c l o s u r e s , t h e g a s s i n g o f a q u e o u s e v o l v e d .e l e c t ro l y t e b a t t e r i e s d o e s n o t p r e s e n t a s e r i ou s h a z a r d . A r e p o r t o f o n - c h a r g e g a s - e v o lu t i on e x p e r i m e n t s o nB y c o n t r a s t , in c o n f i n e d s p a c e s , s u c h a s i n a s u b m a r i n e , s u b m a r i n e c e l l s h a s b e e n p u b l i s h e d p r e v i o u s ly [ 1] . T h e

w o r k d i s c u s s ed h e r e c o n c e r n s t h e m o r e o p e r a t i o n a l l y~ T el .: 0 89 5 45 641 1. c r i t i c a l s c e n a r i o , w h e n t h e s u b m a r i n e i s s u b m e r g e d ,

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J .B . La k e m a n / J o u rn a l o f Po w e r S o urc e s 5 3 (1 99 5 ) 9 9 -1 0 7 10 1

an d t h e b a t t e r y i s e i t h e r o n o p en - c i r cu i t o r o n f l o a t- s u r ed co n ti n u o u s l y u s i ng a p a r am ag n e t i c o x y g en an a -ch a r g e . T h e e f f ec t o f s e r v i ce l i fe o n h y d r o g en - ev o l u t i o n l y ze r ; t h e h y d r o g en co n t en t w as d e r i v ed b y d i f fe r en ce .r a t e i s ex am i n ed b y t e s t i n g b o t h n ew ce l l s an d ce l l s a tt h e e n d o f s e rv i ce . T h e t e m p e r a t u r e d e p e n d e n c y o f ga s 2.2. Electr ical per formanceev o l u t i o n , an d t h e r e l a t i o n s h i p b e t w een ev o l u t i o n r a t ean d e l ec t r ica l d i s ch a r g e p e r f o r m an ce a r e a l s o ex am i n ed . T h e d is ch a r g e p e r f o r m an ce o f t h e t w o b a t t e r i e s w asm e a s u r e d u s i n g a r e c e n t l y d e v e l o p e d m i c r o - c o m p u t e r

con t ro l led , 16-b i t , 0 .5 MW bat tery tes t f ac i l i ty . A sche-2 . Exp er im enta l ma t ic o f the f ac i l ity i s show n in F ig . 1 . D is cha rge/ch a r g e p r o f il e s o f u p t o 4 5 s t ep s o f co n s t an t p o w e r ,

T w o b a t t e r i e s o f s u b m ar i n e ce l l s w e r e t e s t ed . I n each cu r r en t an d re s i s t an ce o n d is ch a r g e , an d co n s t an t cu r -ca s e t h e n eg a t i v e g r id s w e r e m a d e f r o m a b i n a r y r en t o r v o l t ag e o n ch a r g e , c an b e p r o g r am m e d i n an yco m b i n a t i o n . D i s ch a r g e i s a ch i ev ed b y u s i n g r e s i s t i v el ead - ca l c i u m a l l o y , an d t h e p o s i t i v e g r i d s w e r eP b - 3 w t . % S b - l . 5 w t . % S n - 0 . 0 5 w t . % S e [7 ]. O n e b a t t e r y l o ad s ; t h e m a x i m u m c u r r e n t o f 1 6 0 0 0 A is r e s o lv e do f t en ce l l s w as n ew an d w as r ece i v ed i n t h e d r y - t o ~ 0 .2 5 A . C o n t r o l p r ec i s i o n i s l i m i t ed b y t h e s ev ench a r g ed s t a t e . T h e ce l l s w e r e f i ll ed w i t h s u l f u ri c ac i d cu r r en t - m eas u r i n g s h u n t s t o b e t t e r t h an 0 .2 % o f r ead i n g .an d cy c l ed t o t h e r a t ed cap ac i ty ; t h e r a t ed p e r f o r m an ce C h a r g i n g i s c a r r i ed o u t u s i n g a t h y r i s t o r - co n t ro l l edan d ch a r g in g p r o c ed u r e h as a l r ead y b ee n d es c r i b ed an a l o g u e s u p p l y.[ 1,2] . T h e s eco n d b a t t e r y , o f e i g h t ce l ls , w as s e l ec t ed T h e d i s ch a rg e cu r r en t i s co n t r o l l ed b y a r r an g in g t h ea t r an d o m f r o m an en d - o f - li f e s u b m ar i n e b a t t e r y , r e s is t iv e e l em e n t s i n t o t w o , 8 - b it b i n a r y p a t t e r n g r o u p s :o n e h i g h p o w er , th e o t h e r l o w p o w er . T h e h i g h - p o w er2.1. Gas evolut ion l o ad b an k i s s h o w n s ch em a t i ca l l y i n F i g . 2 . P o w erM O S F E T h e a t - s i n k m o d u l e s a r e u s e d t o s w i t c h t h e

C e l l s w e r e i n cu b a t ed i n a t h e r m o s t a t i ca l l y - co n t r o l l ed i n d iv i d u a l r e s is t iv e e l em en t s o f b o t h b an k s . F o r v e r yw a t e r t an k a t t em p er a t u r e s r an g in g f r o m ~ 1 1 t o 5 3 h i g h p o w er t e s t s, t h e l o ad i s s u p p l em en t ed b y f o u rwa ter - co o led r es i s t ive loads . A typ ica l five- s tage cons tan t C . G as - ev o l u t i o n r a t e s w e r e m eas u r ed e i t h e r a t o p en -c i r cu i t fo l lowing a fu l l gass ing charge , o r on a f loa t - pow er d i scharge p ro f i le on the 10-ce ll ba t tery i s g ivencharg e o f 2 .20 to 2 .22 V/cel l . Th e r a te o f gas evo lu t ion in F ig . 3 .w as m eas u r ed co n t i n u o u s l y w i t h e l ec t r o n i c m as s f l o w -m e t e r s . T h e g as co m p o s i t i o n w as an a l y zed i n it ia l ly u s i n g 3 . R es u l t s an d d i s cu s s i o na q u ad r u p o l e m as s s p ec t r o m e t e r , i n o r d e r t o e s t ab l i s ht h a t t h e o n l y s i gn i fi cant co m p o n en t s w e r e o x y g en an d F i g. 4 i l lu s t r a te s t h e v a r i a ti o n , a t o p en - c i r cu it , o f t h eh y d r o g en . G a s co m p o s i t i o n s w e r e s u b s eq u en t l y m ea - h y d r o g en - ev o l u t i o n r a t e ( in cm 3 h -1 ce l l - 1 ) a t STP

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F i g . 2 . S c h e m a t i c d i a g r a m o f t h e h i g h - p o w e r l o a d b a n k .


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T i m e / h o u r sFig. 5. Average total gas and oxygen-evolution rates vs. time on open-circuit after charge for end-of-life submarine cells at 38 C.

( S C C P H P C ) , a g a i n s t t i m e e l a p s e d s i n c e a f u ll g a s s in g t h e m a x i m u m . T h e c o r r e s p o n d i n g t r a c e s f o r t o t a l g a s ,c h a r g e f o r e n d - o f - l i f e s u b m a r i n e c e l l s a t 3 8 C . I n i ti a l ly , a n d f o r o x y g e n , a r e d i s p l a y e d i n F i g . 5 . T h e s e t r a c e st h e r e i s a d e c r e a s e i n f lo w r a t e a s t h e r e s i d u a l g a s a c h i e v e a m a x i m u m i n ~ 1 1 h , f o l l o w i n g w h i c h t h ef r o m th e p r ev i o u s c h a r g e i s r e l e a se d . T h e e v o l u ti o n o x y g e n - e v o l u t io n r a t e g r a d u a l ly d e c l in e s . T h e r e a s o nr a t e t h e n p r o g r e s s i v e l y i n c r e a s e s o v e r ~ 3 0 h t o r e a c h f o r t h e d e c l i n e i n o x y g e n e v o l u t i o n i s u n c l e a r , b u t m u s t


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J.B. Lakeman / Journal of Power Sources 53 (1995) 99-107 10 3

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T ime I hoursFig . 6 . A v era ge h y d ro gen - ev o lu t io n ra t e v s . t im e o n o p en - c ircu i t a f t er ch a rge f o r n ew s u b m a r in e ce l l s a t 3 8 C .

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T ime I hoursFig . 7 . A v era ge t o t a l ga s a n d o x y gen - ev o lu t io n ra t es v s. t im e o n o p en - c ircu i t a f t er ch a rge f o r n ew s u b m a r in e ce l l s a t 3 8 C .

T a b l e 1 m o r e s l o w l y i n t h e c a s e o f n e w c e l l s . T h e a v e r a g e ,T em p era t u re , h y d ro gen content, and average h y d ro gen - ev o lu t io n ra t e s t e a d y - s t a t e , h y d r o g e n f l o w - r a t e f o r o l d a n d n e w c e l l sf o r en d - o f - l i f e ce l l s o p en - c ircu i tn a t 3 8 C w a s f o u n d t o b e 1 0 4 0 a n d 3 1 5 S C C P H P C ,Temperature H2 Hz f lo w ra t e r e s p e c t i v e l y . T h i s i n d i c a t e s t h a t t h e o p e n - c i r c u i t h y -( c) (% ) ( S C C P H P C ) d r o g e n - e v o l u t i o n r a t e h a s i n c r e a s e d b y m o r e t h a n t h r e e -

f o l d o v e r t h e l i f e o f t h e c e l l s .11.4 99 89 R e s u l t s a t o t h e r t e m p e r a t u r e s a r e l is t e d i n T a b l e s22 98.5 18429 9 8 .3 4 9 1 1 a n d 2 f o r o l d a n d n e w c e l l s , r e s p e c t i v e l y . I n e a c h2 9 9 8.2 5 36 c a s e , t h e h y d r o g e n c o n t e n t o f t h e e v o l v e d g a s i s a l w a y s3 8 9 4 . 5 13073 8 9 6 . 7 1 0 26 T a b le 25 3 8 9 . 8 3 7 0 7 T em p era t u re , h y d ro gen co n t en t , a n d a v era ge h y d ro gen ev o lu t io n ra t e5 3 . 3 9 0 . 5 3 8 4 8 f o r n ew ce l l s o n o p en - c ircu i t

T em p era t u re H2 H2 f lo w ra t er e f l e ct a r e d u c t i o n i n t h e a c t i v e a r e a f o r s e l f - d i s c h a r g e ( c ) ( % ) ( S C C P H P C )a t t h e p o s i t i v e , r a t h e r t h a n a n i n c r e a s e i n t h e r a t e o fo x y g e n r e d u c t i o n a t t h e n e g a t i v e . 2 1 9 8 . 9 7 424 .3 9 8 . 9 9 4F i g . 6 il l u s t r a te s t h e v a r i a t i o n i n t h e a v e r a g e h y d r o g e n - 28 .7 9 8 . 9 1 16e v o l u t i o n r a t e a t o p e n - c i r c u i t w i t h t i m e f o r n e w s u b - 3 4 .9 9 8 .9 21 0m ar i ne c e l l s a t 38 C. F i g . 7 s h ow s t he c or r e s p ond i ng 38.3 95.3 361t r ac e s f or t o t a l gas and f or oxy ge n . Co m p ar i s on o f F i g s . 39.7 98.8 3124 and 5 wi t h F i gs . 6 and 7 r e ve a l s t ha t t he hyd r og e n- 44.3 97.2 5575 1 . 5 9 6 . 8 1286e v o l u t i o n r a t e r i s e s , a n d t h e o x y g e n - e v o l u t i o n r a t e f a l l s ,


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104 J.B. Lakeman / Journal of Power Sources 53 (1995) 99-107

9 0 % o r a b o v e . T h i s c o n f i r m s p r e v i o u s o b s e r v a t i o n s t h a t T ab le 4t h e r a t e o f s e l f - d i s c h a r g e o f t h e p o s i t i v e i s s i g n if i c a n tl y H y d r o g e n - e v o l u t i o n data for new cells o n f l o a t - c h a r g el o w e r t h a n t h a t o f t h e n e g a t i v e [ 8 ]. I n t h e c a s e o f o l d T e m p e r a t u r e H 2 f lo w H 2 M e a n c e ll F l o a tc e l ls , t h e r e i s s o m e i n d i c a t i o n t h a t t h e h y d r o g e n c o n t e n t ( c ) (S C CP H PC ) ( % ) v o l t a g e c ur re ntd e c r e a s e s w i t h i n c r e a s in g t e m p e r a t u r e . ( v ) (A )

T h e o p e n - c i rc u i t , h y d r o g e n - e v o l u t i o n r a t e i s f o u n dt o v a r y l o g a r i t h m i c a l l y w i t h t e m p e r a t u r e , a n d t h e r e s u l t s 2 2.4 165 5 7 2.213 1.92 7 2 3 7 5 4 2 . 2 1 5 2 . 3o f T ab l e s i an d 2 a r e p lo t t e d i n F ig s . 8 an d 9 , r e s p ec t i v e ly , 3 0.7 4 84 5 2.5 2 .2 19 4 .8w i t h t h e r e g r e s s i o n e q u a t i o n s i n d i c a t e d . F r o m t h e e q u a - 3 7.8 823 4 9 2 .20 9 6.7t i o n s , t h e o p e n - c i r c u i t , h y d r o g e n - e v o l u t i o n r a t e p e r A h 38 957 5 0 2.219 7.8o f r a t e d c a p a c i t y f o r n e w c e l l s w a s f o u n d t o b e b e t w e e n 4 3.2 1332 4 0 2.218 12.10 .0 0 6 3 6 an d 0 .1 0 5 cm 3 h -1 A h -1 a t S T P , a t 2 0 -5 0 C , 4 8.9 1952 4 4 2 .2 08 13.35 0 . 0 1 6 2 5 4 7 2 . 2 0 0 1 5 . 3r e s p e c t i v e l y . F o r o l d c e l l s , t h e c o r r e s p o n d i n g e v o l u t i o nr a t e s a r e b e t w e e n 0 . 02 3 7 a n d 0 . 36 1 c m 3 h - 1 A h - 1 a tS T P . T a b l e 5Th e s lopes of both p lo ts a re essent ia l ly the same, I n d i v i d u a l h y d r o g e n - e v o l u t i o n r a t e s f o r o l d a n d n e w c e ll s o n f l o a t-and the en tha lpy of ac tiva t ion for open-c i rcui t hydrog en c h a r g e a t 3 8 C a n d t h e i n d i v i d u al e n d - o f - d i s c h a r g e v o l t ag e s ( E D V )a t t h e e n d o f C/5 r a t e d i s c h a r g e o f t h e b a t t e r ye v o l u t i o n i s c a l c u l a t e d a s ,-, 7 0 k J m o l - 1 . T h e s i m i l a r it yo f s l o p e i s i l l u s t r a t e d i n F i g . 1 0, b u t i t c a n b e s e e n C ell O l d c el ls N e w c e l l st h a t t h e r e is a n u p w a r d s h i f t f o r t h e r e s u l t s o f e n d - n um b ero f - l if e c e ll s . T h i s s u g g e s t s t h a t t h e m e c h a n i s m f o r o p e n - H2 f l o w EDV HE flow ED Vc i r c u i t h y d r o g e n e v o l u t i o n i s t h e s a m e i n b o t h c a s e s , ( SC C PH P C) ( V) (SCCPHPC) (V )b u t t h a t t h e a c t i v e a r e a f o r e v o l u t i o n i n c r e a s e s w i t h 1 1731 1 .634 915 1 .662ag e . Th i s i s p r es u m ab ly b e ca u s e o f t h e p ro g re ss i v e 2 1604 1.301 96 0 1.69 0l ea ch in g o u t o f an t im o n y f r o m th e p o s i t i v e g r i d b y 3 1659 1 .7 66 9 64 1.674co r ro s io n , fo l l o w ed b y i t s d e p o s i t i o n o n t h e n e g a t i v e 4 1680 1 .7 66 9 81 1.68 3a c t i v e m a t e r i a l . H y d r o g e n i s p r e f e r e n t i a l l y e v o l v e d f r o m 5 1664 1.760 9 44 1.6656 1 6 7 8 1 . 7 1 2 9 7 4 1 . 6 8 0l o ca l ce l l s o n t h e n eg a t i v e p l a t e b e tw ee n t h e sp o n g y 7 1831 1 .722 96 5 1.70 6l ea d an d t h e d e p o s i t ed an t im o n y [2 ] . 8 1463 1.738 9 55 1.689

T h e o p e n - c i r c u i t , h y d r o g e n - e v o l u t i o n r a t e s w e r e u s e d M e a n 1664 1.675 9 57 1.681t o c a l c u l a t e t h e r a t e o f s e l f- d i s c h a r g e . T h e d a t a a r e S t a n d a r d 1 0 4 .9 0 . 1 5 7 2 0 . 6 0 . 0 1 4s u m m a r i z e d i n F i g . 1 1 . A t 2 0 C , t h e s e l f - d i s c h a r g e d e v i a t i o nr a t e s o f ol d a n d n e w c e ll s a r e f o u n d t o b e 5 0 a n d 1 4 %p e r y e a r , r e s p e c t i v e l y ; t h i s d a t a s h o u l d b e c o m p a r e dw i t h t h a t o f L i n d e n [9 ]. I n t h e p r e s e n t c a s e , t h e r e s u l t s a n d n e w c e l l s a r e s i m i l a r , a n d t h e r e i s a s i g ni f ic a n ts h o w a n i n c r e a s e d t e m p e r a t u r e d e p e n d e n c y . I t s h o u l d i n c r e a s e in t h e o x y g en c o n t e n t o f th e e v o l v e d g a sb e r e m e m b e r e d , h o w e v e r , t h a t t h e ra t e is d e t e r m i n e d c o m p a r e d w i t h t h e o p e n - c i r c u i t c a s e. T h i s s u g g es t s t h a tb y m a n y f a c t o r s , i n c l u d in g t h e l e n g t h o f s t o r a g e , t h e r e i s a F a r a d a i c c o n t r i b u t i o n t o g a s e v o l u t i o n . T h e

T a b l e s 3 a n d 4 s u m m a r i z e f l o a t - c h a r g e d a t a fo r o l d h y d r o g e n c o n t e n t o f t h e e v o lv e d g a s w a s g r e a t e r f o ra n d n e w c e l ls , r e s p e c t i v e l y . T h e c e l ls w e r e m a i n t a i n e d t h e o l d c e ll s, b u t d id n o t s h o w a n y t e m p e r a t u r e d e -o n f l o a t- c h a r g e , w i t h n o t e m p e r a t u r e c o m p e n s a t i o n o f p e n d e n c e . F o r t h e n e w c e ll s, t h e r e is s o m e i n d ic a t i o nt h e a p p l i e d v o l ta g e . T h e f lo a t c u r r e n t s a c h i e v e d f o r o l d o f a d e c r e a s e i n h y d r o g e n c o n t e n t a s t h e t e m p e r a t u r e

i n c r e a s e s .T ab le 3 F i g s. 1 2 a n d 1 3 a g a i n d e m o n s t r a t e a l o g a r i t h m i cH y d r o g e n - e v o l u t i o n d a t a f o r e n d - o f - l if e c e l ls o n f l o a t - ch a r g e r e l a t io n s h i p o f h y d r o g e n - e v o l u t i o n r a t e w i t h t e m p e r -T e m p e r a t u r e H 2 fl ow H 2 M e an c el l F lo at a t u r e . I n t h i s c a s e , t h e s l o p e s a r e n o t t h e s a m e , a n d( C ) ( S C C P H P C ) ( % ) v o l t a ge c urre nt t h e o l d c e l l s d e m o n s t r a t e a g r e a t e r t e m p e r a t u r e d e -

( v ) (A ) p e n d e n c e . F r o m t h e r e g r e s s i o n e q u a t i o n , t h e h y d r o g e ne v o l u ti o n r a t e p e r A h o f r a t e d c a p a c i t y f o r n e w c e ll s1 9.5 198 6 4 2 .2 08 1 .2 w as fo u n d t o r a n g e b e tw ee n 0 .0 1 6 6 an d 0 .2 4 1 cm 3 h - 12 3 3 9 8 6 9 2 . 2 0 8 2 . 32 5 5 19 6 9 2 .2 14 2 .6 A h -1 a t S T P , a t 2 0 - 5 0 C , r esp ec t i v e ly . F o r o ld ce l l s ,

29.5 855 67 2.215 4.3 t h e c o r r e s p o n d i n g r a t e s w e r e f o u n d t o l i e b e t w e e n34 1209 63 2 .211 5 .5 0 .029 8 an d 0 .903 cm 3 h -1 A h -1 at ST P.3 8 1664 6 5 2 .2 10 7 .2 T h e r es u l t s h ig h l i g h t t h e s i g n i f i c an t im p a c t t h a t ce l l43 5184 64 2.211 1 0 . 0 t e m p e r a t u r e m a k e s o n t h e r a t e o f h y d r o g e n e v o l u t i o n5 1 . 5 7 6 5 8 7 1 2 . 2 0 8 1 6 . 3 d u r i n g f l o a t c h a r g e , w h e n t h e a p p l i e d v o l t a g e is n o t


7/9

J.B. Lakeman / J ou r n a l of Power Sources 53 (1995) 99-107 10 5

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4 I I I I I I I I I I0 . 0 0 3 0 5 0 . 0 0 3 1 0 . 0 0 3 1 5 0 . 0 0 3 2 0 . 0 0 3 2 5 0 . 0 0 3 3 0 . 0 0 3 3 5 0 . 0 0 3 4 0 . 0 0 3 4 5 0 . 0 0 3 5 0 . 0 0 3 5 5

1 / T ( I L K )F i g . 8 . P l o t o f I n H 2 f l o w r a t e ( S C C P H P C ) v s . T - t ( K - t ) f o r e n d - o f - l i fe c e l l s o n o p e n - c i r c u i t .

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3 I I I I I I I I I I0 . 0 0 3 0 . 0 0 3 0 5 0 . 0 0 3 1 0 . 0 0 3 1 5 0 . 0 0 3 2 0 .0 0 3 2 5 0 . 0 0 3 3 0 . 0 0 3 3 5 0 .0 0 3 4 0 . 0 0 3 4 5 0 . 0 0 3 5

1 / T ( I L K )F i g . 9 . P l o t o f I n H 2 f l o w r a t e ( S C C P H P C ) v s . T - t ( K - t ) n e w c e l l s o n o p e n - c i r c u i t .

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1 [ 1 " ( l / K )F i g . 1 0 . P l o t o f I n H 2 f l o w r a t e ( S C C P H P C ) v s . T - I ( K - 1 ) f o r e n d - o f - l if e a n d n e w c e l l s o n o p e n - c i r c u i t .

c o m p e n s a t e d f o r t e m p e r a t u r e . F o r n e w c e ll s , t h e r e i s e f f e c ti v e t e m p e r a t u r e c o m p e n s a t i o n i s n o t f e a s ib l e . Aa 14- fo ld increase in ra te on moving f rom 20 to 50 C; s imi lar s i tuat ion w i l l perta in in any l arge bank o ff o r o l d c e l l s i t i s a 3 0 - f o ld i n c r e a s e . I n t h e c o n f i n e s o f b a t t e r ie s o r c e l l s a n d a d e q u a t e p r e c a u t i o n s m u s t b ea subm arine bat tery tank , indiv idua l ce l l t emp eratur es tak en .c a n v ar y w i d e l y , d e p e n d i n g o n l o c a t io n . T h e r e f o r e , l a rg e T h e t w o b a t t e r ie s w e r e d i sc h a r g e t e s t e d in o r d e r t ovaria t ions in gas -evo lut ion ra te can be expected , but es tabl i sh the re la t i onship bet we en the d i scharge per-


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1/ ' r ( l /K)Fig. 13. Plot of In H2 flow rate (SCCPHPC ) vs. T -~ (K -~) for new cells on float-charge.

f o r m a n c e a n d t h e h y d r o g e n - e v o l u t i o n r a t e i n c e ll s . A t a t 3 8 C . T h e s t a n d a r d d e v i a t i o n s i n d i c a t e t h e i n c r e a s e dthe C /5 rate, the end-of-life battery of cells was found variability in behaviour of old cells compared with newt o h a v e s u f f e r e d a 1 3 . 7 % r e d u c t i o n i n c a p a c i t y o v e r c e ll s. E n d - o f - d i s c h a r g e v o l t a g e s ( E D V s ) a r e a l s o l i s te di ts se r v i c e l i fe , w h i l s t t h e b a t t e r y o f n e w c e l l s a c h i e v e d f o r t h e i n d i v i d u a l c e l l s a t t h e e n d o f a C /5 r a t e d i s c h a r g e .t h e r a t e d c a p a c i t y . T a b l e 5 l is ts t h e i n d i v i d u a l h y d r o g e n - A g a i n , a n in c r e a s e d s p r e a d i n p e r f o r m a n c e i s s e e n f o re v o l u t i o n r a t e s f o r o l d a n d n e w c e l l s o n f l o a t - c h a r g e e n d - o f - l i f e c e ll s . T h e d a t a a l so d e m o n s t r a t e t h a t t h e r e


9/9

Z B . L a k e m a n / J o u r n a l o f P o w e r S o u r c e s 5 3 ( 1 9 9 5 ) 9 9 - 1 0 7 10 7

i s n o c o r r e l a t io n b e t w e e n t h e d i s c h a r g e p e r f o r m a n c e 5 . T h e o p e n - c i r c u i t h y d r o g e n e v o l u t i o n r a t e c a n b eo f in d i v i d u a l c e ll s a n d t h e c o r r e s p o n d i n g h y d r o g e n - u s e d as a n i n d i c a t o r o f t h e r a te o f s e l f- d i s ch a r g e o fe v o l u t i o n r a t e . T h e s a m e b e h a v i o u r i s a l so o b s e r v e d t h e n e g a t iv e p l a t e .f o r c e l ls o n o p e n - c i r c u i t . T h e i n d i v i d u a l c e l l s a r e c o n - 6 . O n o p e n - c i r c u i t , t h e r a t e o f s e l f - d i s c h a r g e o f t h es i s t e n t , h o w e v e r , i n t h e i r h y d r o g e n - e v o l u t i o n r a t e s a n d p o s i t iv e p l a t e is s i g n i f ic a n t l y l o w e r t h a n t h a t o f t h ei n t h e i r d i s c h a r g e p e r f o r m a n c e s . E n d - o f - l i f e c e l ls w e r e n e g a t i v e , a n d p r o g r e s s i v e l y f a l ls w i t h t i m e .f o u n d t o h a v e s u f f e r e d a s i g n i f i c a n t r e d u c t i o n i n d i s - 7 . G a s - e v o l u t i o n l e v e ls w h e n f l o a t c h a r g i n g a t ~ 2 . 2c h a r g e p e r f o r m a n c e o v e r t h e i r s e r v i c e l i fe , b u t t h e r a t e V / c e l l a r e s i g n i f ic a n t l y h i g h e r t h a n o n o p e n - c i r c u i t , a n do f h y d r o g e n e v o l u t io n o n f l o a t- o r o p e n - c i r c u i t s ig n if - t h e o x y g en c o n t e n t is h i g h e r .i c a n t ly i n c r e a s e s o v e r t h e s a m e p e r i o d . T h i s m e a n s t h a t 8 . F l o a t c h a r g i n g w i t h o u t c o m p e n s a t i n g t h e a p p l i e da l t h o u g h th e a ct iv e a r e a f o r e l e c tr i c a l d i s c h a r g e h a s v o l t a g e f o r c e ll t e m p e r a t u r e c a n l e a d t o a d r a m a t i cr e d u c e d , t h e a c ti v e a r e a f o r h y d r o g e n e v o l u t i o n h a s i n c r e a s e in t h e r a te o f h y d r o g e n e v o l u ti o n as th ei n c r e a s e d , p r o b a b l y b e c a u s e o f t h e p r o g r e ss i v e t r a n s - t e m p e r a t u r e r is e s .f e r e n c e o f a n t i m o n y .

R e f e r e n c e s4 . C o n c l u s i o n s[ 1] J .B . L ake man , J . P o w e r S o u rc e s , 2 7 (1989) 155-165.1 . F o r c e l ls o f t h e s a m e a g e , t h e g a s - e v o l u t i o n r a t e [21 N .E . Bagshaw, J . Po w e r Sour c e s , 4 0 ( 1992) 113-122.f r o m a c e l l o n o p e n - c i r c u i t , o r o n f l o a t - c h a r g e , d o e s [31 M . M a j a a n d N . P e n a z z i , J . Pow e r Sour c e s , 22 91988) 1-9.n o t c o r r e l a t e w i t h i ts e l e c tr i c a l d i s c h a r g e p e r f o r m a n c e . [ 41 M. Johnso n , S .R . E l l is , N .A . Ha mps on , F . Wi lk inson and M.C.Bal l , J . P o w e r S o u r c e s , 2 2 ( 1988) 11 - 20 .2 . A s a ce l l ages , i t s ga s -evo lu t i on r a t e i nc rea se s bu t 15l L .T . Lam, J .D. Doug las , R . P i l l i g and D.A.J. Rand, J . Pow e ri t s d i s c h a r g e p e r f o r m a n c e d e c r e a s e s . T h e m e c h a n i s m Sour c e s , 4 8 ( 1994) 219-232.f o r o p e n - c i r c u i t h y d r o g e n e v o l u t i o n d o e s n o t c h a n g e [ 6] S . Ven ugop a l an , J . Pow e r Sour c e s , 4 8 (1994) 371-384.wi t h age . [7 l H . W a t e r h o u s e a n d R . W i l l o w s , B r . P a t e n t N o . 6 2 2 5 1 2 (1949) .

3 . T h e a c t i v e a r e a f o r h y d r o g e n e v o l u t i o n i n c r e a s e s [8 l A . J . S a l k i n d , G . E . M a y e r a n d D . L i n d e n , i n D . L i n d e n ( e d . ) ,H a n d b o o k o f B a t te r i es a n d F u e l C e l ls , M c G r a w - H i l l , N e w Y o r k ,wi t h age , bu t t he ac t i ve a re a fo r d i sc ha r ge dec r ea se s . 1984, pp. 14-17.4 . H y d r o g e n e v o l u t i o n r a t e s a t o p e n - c i r c u i t a n d f l o at - [ 9] D . L inden , i n D . L inde n (ed . ) , H a n d b o o k o f B a t te r ie s a n d F u e lc h a r g e v a r y l o g a r i th m i c a l l y w i t h t e m p e r a t u r e . Cells, McGr aw- Hi l l , New Yor k , 1984 , pp . 13 - 18 .

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