1.
 Effect of Preparation Method of Catalytic Layer on the Performance of Polymer Electrolyte Membrane Fuel Cells
  

         

  ***^†

* 

**   

(2000 8 28! "#, 2000 11 2! $%)

Effect of Preparation Method of Catalytic Layer on the Performance of Polymer Electrolyte Membrane Fuel Cells

Jeong-Kyu Lee, Heung Yong Ha, Seong-Ahn Hong, Hai-Soo Chun*, Tae Won Lim** and In-Hwan Oh^†

Battery and Fuel Cell Research Center, Korea Institute of Science and Technology

*Department of Chemical Engineering, Korea University

**Fuel Cell Vehicle Team, Hyundai Motor Company (Received 28 August 2000; accepted 2 November 2000)



'( 78 9 1/3 :
, 5 *+,- ;< &'() 1/4,  =. &'( >? 3/43@ *+,-A  / B* CD EF G H IJ$. K &'LM N  KO 9P Q@*RO SK?  H T*U VVW XYZ [\]V ^_`  * _J$.  NO ab  cd ef O. Fg hi jkO l dm nO*o pq( *Kr  nO l s [tu$.

Abstract−The performance of polymer electrolyte membrane fuel cells(PEMFC) has investigated by varying composition of the electrodes which consist of catalyst and proton-conductive ionomer. Their performance appeared to be significantly affected by the total amount and the distribution of the ionomer in the electrodes. The best performance was obtained when the ionomer content was 1/3 of the total amount of the catalyst(by weight); but, 1/4 of the ionomer was inside the catalytic layer and 3/4 at the interface between the catalytic layer and polymer electrolyte membrane. The performance of the electrodes was also influenced by the preparation method of catalyst inks which were composed of solvent, catalyst powders and ionomer solution, in such a manner that the so called “colloidal method” showed better results than did the conventional “solution method”. The former method appeared to secure continuity of the ionomer network and also a higher porosity in the catalytic layer, resulting in a higher proton conductivity and a less mass transfer resistance. The effect of preparation methods was inves- tigated by employing the various electrochemical analysis techniques.

Key words: Fuel Cells, PEMFC, Electrode, Colloidal Method, Ionomer

†E-mail: [email protected]

1.  

        

 Carnot’s    
 !" #$  

%& ' ( ) *+ ),-, . / 01 234 5 6

78 9:;  <=  >?@ ABCD BEFG "H

D4 ID J
KL +MNO )". PQ ORA  1

  1 S3+ 6O T$ U4 VB- WX+ 6 Y Z[\, stack design ]^_, ` aEC 9 bK_, c (d e

*, fg ABCh +BF L i= jk fXlO )

"[1].

 _m #+ J  n o_p Ko qiL +MNrs -, PQ n I_ 01 tDl uv wxyz H

 {+O n_m |}>~ J  nb I_* € L>s ". ‚ƒh  1 tDl ORA „$ O… lN ) N n yz†p  1p ‡ˆj_ ‡L )". ‰\, +ƒ

 ‡ˆ ˆi €L>~ J  yz† hŠU ‹$ +Œ

Ž& > yz +ŒŽ ‘y |}> ’Ns -, +7 j_“ ”} ‡ˆ  yzf wx +D+ #Z• “". ‚ƒ

h hŠU$  –
…+ 78 —˜ ™ˆ š›• œ• ž Ÿ

 39 1 2001 2

  A +B ¡ • “". q¢ N wxp ORA  1 t + ‡ˆ ˆi €L>~ J  £$ ¤+ ¥lO )¦, Liu e[2]$ ORA„ ™ˆ -§F /¨, wx 4x©O,

Verbrugge[3] wx +U ªO )  1 tD  4x

«  yz† ™ˆ J wx† j_4 ©". ‚ƒh +ƒ

 ¡«$ P¬ ¤p ­® o/¨+ ¯Kl° ± i,

 yz†² 4³ ]´ /¨+ £+ tDlO )". Uchida e[4]

$ +ŒŽ µ+¶ D· wxyz ¸¹º »¼“ ½ R¾ (PTFE-C) ¿N yz ÀÁ& oO, + ½Ã+ J R, gp>~ ¡«  n og Ä$ _m 'Å,-,

Giorgi e[5]$ ½Ã+ J ¸¹ºp ½R¾+ ¿f Ɔ 4³

O ‚ J yz† ÇN n o©".

˜
K n K_¯L ´J _m È É| O Ê J yz†  1 Ëp yz ÀÁ o ¡«+


 _m È É| ÌÍ!Î". ., i Ï 0Ði ¡«

 tDg n P_ RÑ©".

2.  

2-1.
    

yz ÈÒ ½ÓA(Vulcan XC-72R) wx+ R“ Pt/C(E- Tek)& tD©O, yz … PTFE& 20% ª —˜ Ã+

(TGPH-060, Toray)& tD©".  1„$ Nafion 115(Dupont)&,

 1 D·$ 5% Nafion D· tD©".

yz 10-60 wt% Pt/C& tD©,-, n >Ô +ŒŽ

 H$ Õl yz ֕ 9g 1/6 1/2 ×>Ø". yz R¾ +ŒŽ& >Ù 7 tD Dz isopropyl alcohol (IPA, Ú4 99.5%) normal butyl acetate(NBA, Ú4 99%) š ÃÛ

& tD©". IPA& Dz tD “ 1 D «” Dz +ŒŽL ÜQ D lN l°, yz R¾p IPAL Ý=“ D

· i¨ hŠU D· ±> Ý=g yz ÀÁ& o©".

“ 1 µ+¶«”$ IPA!" Þ(_+ i$ NBA& Dz tD

°ß +ŒŽL µ+¶ jk à• l¦, yzR¾p NBA L Ý=“ D· áâã ä ˆ hŠU D· oxå æNç è Ý=g yzÀÁ& o©". + ‹$ ¡«, o  n oD ÀÁ& —˜Ã+ J ?¹é+ »¼> yz† j_>

Ø". o“ ꍶ Ï ë¶ np hŠU 115 „ 140^oC Ï 200 atm oì 90á]  aí g  1/n ‘=…(membrane- electrode assembly, MEA)& o©".

2-2.

ªL j_“ î
ïp ðMÈñ O¨ï, +MNò  ó  n ˆi 25 cm² MEA& íg ´J _m ô¨©". n  _m ô¨ Jg Û W(electronic load, Daegil electronics, EL 500P)& +Dg  ap Û& ô¨©".  õo ì$ VB U4 80^oC, VBaE 1a, ©,-, Lö“  (

& ë¶ ꍶ /÷©". i I_ ™ˆi ô¨

 Jg Vø nf ë¶ 1& /÷O, ù n+A }9

nf ꍶ (& /÷g potentiostat/galvanostat(EG&G, M 273) Ú§J« +Dg ë¶ ( úí & RÑ©, -[6], impedance analyzer(EGûG 5210 LOCK-IN Amplifier)& tD

g 1 mHz 50 kHz frequency üJ 5 mV òý äÛ ÓE 9 Û& ô¨g MEA þÿ ô¨©".

IPA NBA Dz b yz +ŒŽ ÓA Á& ô¨ J  dynamic light scattering f Zeta Master(Malvern Instruments,

England)& tD©O, yz† b /R³& ô¨ Jg ($

/ô¨(Micromeritics 9220)& tD©".

3.  

3-1.    !" #$

± i, yz† ORA  1(+ŒŽ)& >~ ¡«,

 yz† ™ˆ  1 D·
  ìo>~ ¡« tD

". o“ yz†$  1 „p   aí>~ˆ yz† ™ˆ +

ŒŽ†+ yz†, • lN yz† b +UL j_“

". ‚ƒh + Ÿ  +U L yz† ™ˆ² lO

 yzL }WR à• “". ‰\ +& ¥ >~ J yz† op¨ yz  1 D· Ý=g +U  ŸL yz†b ±• R³l4  ¡« tD4 "[7-9].

˜
K yz†b +ŒŽ R³& ±• O yz†

p  1 „ ‡ˆ +U4_p ‘=_ |}>~ J , yz

  1 D· Ý=g yz† oO ‚ ™ˆJ ">  1 † j_>~ ¡« tDg n o©".

Fig. 1$ ¸¹º yz ֕ 9g 10%»¼ 20 wt% wx Õ

yz& tDO  1 D « tD oì, n Õl

hŠU H ‰ _m ×& h Â+". g +Œ

Ž H$ n yz(Pt/C) ֕ 9 }9if ֕u hbÅ".

Fig. 1 ð ( )  ‹+ +ŒŽL yzH 1/3± 7 L Ä

$ _m !©,-, ‚ +}, €Lˆ _mœL Á• h

". yz†b +ŒŽL p"• Õlˆ n /+ œ

g 0p _0 01 þÿ+ €L• lO, hŠU+ w

hŠU$  W4…+° n  _“ A +B ¡

 þÿ • l°ß n _m+ œ• l Â+".

Fig. 2 +ŒŽ …Ë ±¨• ª>Ô oì yz†

 +ŒŽ R³ ‰ É| Ì͘ Â+". ‚ h 

‹+ hŠU R³Ë$ … ¯ hŠU H 1/4(yzH ù, 

ˆ yz֕ 1/12) yz†, 3/4(yz֕ 1/4) ‡ˆ >

 { 7 0.6 V 816 mA/cm² L #$  _m hbÅ".

Fig. 1. Effect of ionomer contents in the electrode on the cell perfor- mance. Pt/C=20 wt%, solvent=IPA, H₂/O₂=1/1 atm, and T=80^oC.

‚ +}, €Lˆ _mœL Á• hh¦, +Â$ yz†b +ŒŽL p"• Õlˆ n /+ œlN 0p  _0 01 þÿ+ €LlO ., +ŒŽL wxÓA& œ•

Fig. 3$ hŠU R³ ‰ i ˆi Ú§J« 

ô¨ p h Â+- wx™ˆ (FA monolayer L í/úí ¯ & 220µC/cm², L¨O ‚ ‰

roughness factor& ‡g Table 1 5©"[10]. i

ˆi$ Fig. 2 _m p ‹$ Ÿ| hbO )".  y z† à +ŒŽË+ €LO ‡ˆ l H+ VZ1 (  _m+ œO )¦, +Â$ yz† ™ˆ  1Ë+

œˆ yz†p  1 „ t+ ‡ˆþÿ+ €LO ., yz

†b hŠU+ p4• à• lˆ yz† /+ œg

… _0 01  þÿ+ €L 78f Â, !f".

^, +ŒŽ& ;š ‡ˆ² 4³© 7 ` _mþL ± Nh ÎO, i ˆi4 Á• œ Î". +Â$

?¹é+ «, hŠU D· yz† ™ˆ 4³ Ÿ  +Œ

Ž ±WL yz† bW lˆ
if +ŒŽ  !Á

& j_,ß (+U  D+•  p& hb 7 8f Â, !f".

3-2. % & ' () !" #$

± i, n Õl wx H+ £( n _m+ € L• “". ‚ƒh Curtis e[11]$ yz H+ €L( yz†

šL š"!r …f  Æ+ Nè!• lO ‰\, 01  þÿ €L f wx +D+ TZò"O !O  )

". ‰\ ˜
K qi yz† š wxË ðZ!

J n Õ“ wxË 0.1 mg/cm² 1 mg/cm²G ×>

‚ ‰ _m ×& ÌÍ!Î". Fig. 4 wx ÕË ‰

 _m ×& h Â, 400 mA/cm²+ T$ Û#4 É

 yzÕË+ €L( _m+ €L©,h, 400 mA/

cm²+} #$ Û#4 oì 0.1 mg/cm² 0.4 mg/cm²G

 wxË+ €L ‰\ _m+ €LlÅ,h, wxË 1.0 mg/

cm² ÷$ _m þL h". +Â$ #$ Û#4 É

 wx ÕË+ 0.7 mg/cm²+}+ lˆ 01 þÿ+ €L

78, !f". , ꍶ 0 /÷+ W% O ë

¶ _“ 0+ FIQ 5l Z &('}+ hh• l N n_m+ œ• l Â+". . Table 2 wx ÕË ‰

 yz† š _m uä Â+". ‰\ yz† š 50µmf Fig. 2. Effect of the ionomer distribution in the catalytic layer on the

cell performance. Pt loading = 0.7 mg/cm², Pt/C=20 wt%, solvent

=IPA, H₂/O₂=1/1 atm, and T=80^oC.

in: relative amount of ionomer in the catalytic layer, on: relative amount of ionomer on the surface of the catalytic layer.

Fig. 3. Cyclic voltammograms as a function of ionomer distribution in the catalyst layer(scan rate 50 mV/s), Pt loading = 0.7 mg/cm², 20 wt% Pt/C, Ca./An. = N₂/H₂, at 80^oC and 1 atm.

Table 1. Roughness factors of electrodes with Nafion distribution Ionomer distribution

in 0 1/12 1/6 1/4

on 1/3 1/4 1/6 1/12

Roughness factor 28.56 35.51 27.51 27.48

Fig. 4. Effect of the Pt loading on the cell performance. Ionomer content

=1/3 of catalyst, Pt/C=20 wt%, solvent=IPA, H₂/O₂=1/1 atm and T=80^oC.

 39 1 2001 2

0.4 mg/cm² wx ÕË+ qi( ð ( )".

3-3. *+, -.+   

n wx +D €L>~ J  —˜ ™ˆ Õ“ wx

+ŒŽL yz†b à ;) wx ÓA ‘yˆ yz Ó A t+
if +U & j_>~4 s ". ˜
K  tD no ¡«$ ?¹é+& +Dg yz ÀÁ& ½

Ã+ J »¼ Â,ß, + ¡« tDˆ yz ±WL ½

 LrŒ• “". yz† op¨ hh +ƒ '} „, èˆ yz ÀÁb yzÓAp hŠU t,] -E €9> ‘ y |}>.p B>, yz-hŠU -… Á _ ª4g yzÓAL ½Ã+ bW l 4 ˆ Lm Â+". ‰

\ ˜
K yz† o¡« ¥  J  1 µ+

¶« >4©".

hŠU$ Þ(_p Þª_ B> /O ) ORA 01ß, t D“ Dz n_ ‰\ Ü D lN ± Dz& j_5h .

 D l O -lN 0 j_4 ". 0& N Þ (_+ 1 ðµf IPA(isopropyl alcohol)  ÜQ D lN

± D· j_h, Þ(_+ V$ ?¸2 ‡ NBA(normal

butyl acetate)  ÜQ D l O µ+¶ jk -

…& j_g R“". ˜
K Þ(_+ V$ NBA& Dz

tDg hŠU +ŒŽ& µ+¶ >~O, +ŒŽ µ+¶L yz ÓAp -l4 ª4©". + ¡« tDg o yz ÀÁ yz† oˆ yz† b +ŒŽ
if  3 + j_lO, yz +ŒŽ] ‘y+ |}l-[12], . yz-hŠ

U -… 4NÐL 5r yz† /+ €Lg 01 þ

ÿ+ œ". , wx +D+ €LlO +ŒŽ†+ —˜ ™ˆ

}9i, 6• j_lN A  þÿ+ œ• “"[13]. Uchida e[12]$ J ¡«, o“ +ŒŽ yzR¾+ ¿f ÀÁ& —

˜Ã+ J R> Dz& 5 gp« tDg yz† j _>Ø". ‚ƒh, µ+¶« tD Ÿ 4 yz† bW +

ŒŽL p"• à• lˆ yz† / œ, wx ÓA + D þ Ï  4_ þ e, f  _m+ œž ( )

". ‰\ ˜
K yz† 7L +ŒŽ 8 ±W

µ+¶ D· o> 7Lg yz† Õ>~O, hŽ yz†

™ˆ 9L 4³©". yz† J 9L 4³“ +ŒŽ 9 WR+ yz† J àg MEA o>  1 „p yz† t+

‡ˆ þÿ œ>~• lO, ‚ 8 ±WR$ yz† / bW 

g -…] +U  • “".

Fig. 5 yz ÀÁ Dz IPA& tD np NBA& tDg hŠU µ+¶ ¡«, o n _m uä Â+". 

_m$ 0.6 V ù, IPA& tD n+ 728 mA/cm² hbÅ O, NBA tD> 868 mA/cm² _m !g : 20% _m |}

 hbÅ".

Fig. 6$ Dz IPA& tD D «p NBA& tD µ+¶«,

 o n  i ˆi ðZ! J Ú§ J«

, RÑ p& h Â+". Fig. 6 h ( úí 

& +Dg wx ´J ֕ ˆi ‡ p, µ+¶«,

 o n+ 81 m²/g+O, D «, o n+ 42 m²/g h

bN µ+¶« tD Ÿ  n ˆi+ : 30% €L

 ð ( )Å".

Fig. 7$ Dz ÃÛ ‰ Rn þÿ(polarization resistance)×& ð Z ! Jg 0.9 V impedance RÑ p& h Â+". 

 þÿp Æ þÿ  hb Rn þÿ[5, 14]$  1 µ

+¶ « tD Ÿ L D « tD Ÿ !" 0.9 V 7Ωcm²

¨4 {NÅ". + RÑ pW; NBA Dz& tD  1 µ

+¶ ¡« tDg n oˆ yz ™ˆ hŠU †+ 6•

j_lN A þÿ+ œlO ., yz†b /+ €LlN Æ þÿ+ œ< ð ( )".

+} Ì͘  ‹+ yz ÀÁ P_ ‰\ o“ n

 i I_ ` C+L h". +ƒ C+ yz ÀÁ Ï

o“ n 0Ði P_p =+ ) Â+". ‰\ +ƒ 0Ð Table 2. Physical properties of electrodes

Properties Solvent

Pt/C-Nafion agglomerate size (nm)

Catalytic layer thickness(µm)

IPA avg. size 550 20

polydispersity 0.044

NBA avg. size 736 40

polydispersity 0.487

Fig. 5. Effect of the catalytic ink solvents on the cell performance. Pt loading=0.4 mg/cm², Pt/C=20 wt%, H₂/O₂=1/1 atm and T=80^oC

Fig. 6. Cyclic voltammograms for the different catalytic ink solvents (scan rate 50 mV/s). Pt loading=0.4 mg/cm², Ca./An.=N₂/H₂=1/1 atm, and T=80^oC.

i P_ ðZ! J > Dz& tDg o yz ÀÁ ÓA Á n yz† š& RÑg Table 3 hbÅ". Table 3  5  ‹+, yz ÀÁ RlN ) µ+¶ ÓA , h

ŠU + yz -… Á NBAL IPA!" 180 nm ? Á• hh, NBA Dz& tD Ÿ  ÀÁ yz -…L Á• _ ð ( )". . B± wx Ë yz† š4 NBAL IPA!"

20µm¨4 ? š"õ Â, h". yz -… ÓAL 5•

lˆ yz† j_> †f —˜Ã+ bW l yz H+

{NN yz *++ iNO, . … /÷+ FI•

lN pi, Fig. 5 @ ( )A+ 500 mA/cm²+} #$  Û#4 É 01   '}+ }Q œ• “".

3-4. /01   

… p ( +U 44 ¥ gW& ðZ! Jg

n Ko& š ¥ † , yz†p þÿ†, K_g ‚ É|

ÌÍ!Î"[15]. þÿ†$ nb … Æ . (+U

þÿ €9>.,ß _m É| È• “". ‰\ þ ÿ† ooì+ (+U p 01 NB É| È

& ãC ( )". þÿ†$ ½R¾p hŠU +ŒŽ +MN D,-, tD“ ½R¾ H$ yz† à yzR¾ wx

 E ½Ëp B±O, +ŒŽ4 yz† B± H,

FN’Å". +7 þÿ† ÀÁ Dz IPA . NBA& tD©O

;) n yz†$ NBA& tD µ+¶«  o©".

þÿ†$ +ŒŽ ½R¾ +MNr ) 78 

$ ±Nh O … Æ . (+U  

² •“". Fig. 8$ þÿ† J& h Â,, (a) ‹+

þÿ†+  1 „p yz† t+ à• lˆ n _m$ þ ÿ†  ( +U 44  G l-, (b) ‹+ þÿ†+ ½

Ã+†p yz† t+ à• lˆ n_m$ þÿ† 

… Æ4  G “".

Hþ yz†p  1 „ t+ þÿ†+ à n oO, +7 þÿ† o> Dz& ×> ‚ É| ÌÍ!Î". Fig. 9 h  ‹+ IPA& Dz tD  1 D « +Dg  o þÿ†, K_“  _m$ 0.7 V ù, 16 mA/cm²&

hbÅO, NBA& Dz tD µ+¶«, o n$

36 mA/cm² _m !©". +ƒ _m$ þÿ†+ 6 Ÿ  _m (350-400 mA/cm² at 0.7 V) u z  T$ I,ß np  1 „ t+ þÿ†+ à,ß (+U þÿ+ €Lg _m+ Á• œ©â ð ( )". .  1 D « u µ

+¶«, o þÿ† _m+ #• h Â$ NBA&

Dz tD µ+¶« tDˆ þÿ†b hŠU }J

Fig. 7. Nyquist plots of the electrodes at 0.9 V for the different catalytic ink solvents.

Table 3. Cell performance and thickness of the catalytic layer with Pt loading amounts

Pt loading(mg/cm²) 0.1 0.2 0.4 0.7 1.0 Current density(mA/cm²) 712 772 816 816 684 Thickness of catalytic layer(m) 10 30 50 100 190

Fig. 8. Schematic diagram of the multilayer electrode system.

(a) System for proton conductivity, (b) System for mass transfer.

Fig. 9. Effect of the resistance layer to proton conductivity on the cell per- formance.

 39 1 2001 2

+ |}lN ( +U 44L |}l 78, ﴓ".

Fig. 10$ þÿ† yz†p ½Ã+ t+ J> o n

 _m h Â,, þÿ†  01 þÿ É| Ì Í ˜ Â+". ‚ !ˆ _m$ 400 mA/cm² + T$  Û#4 É þÿ† É|+ 5 6,h, 600 mA/cm²+}

OÛ #4 É þÿ† É|+ Á• hhO )". 0.4 V&

ù,  7  1 D « tD n _m$ 864 mA/cm²&

hbÅO, µ+¶« tD 7 1,044 mA/cm² _m hbN PQ, OÛ É µ+¶« pL š¶ƒ• h". +

ƒ p µ+¶« tD n yz-… ÁL _

lO ‚ ‰ n /+ €LlN … Æ+ !" F I• l 78, ﴓ".

3-5. 234 56 #$

± i, ORA  1
 n Ko +8†, lN ),h, q¢ ”†Ko n tD >4L +MNO )"

[5]. +8† n$ (_ ª †(—˜Ã+)p +ŒŽ& 

ª yz†, K_lN ),-, ”†Ko n$ †(—˜Ã+) J ¸¹ºp ½R¾ +MNò Ɔ Õ>~O, + J "

> +ŒŽ& ª yzR¾ j_> o".

+8† n L ` 8*$ yz† †f —˜Ã+ J K‘ 4³ 78 yz† ±WL "/_ —˜Ã+ bW 

• l Â+". ‚ƒh —˜Ã+ J ¸¹º+½R¾ “ Ɔ

6• 4³ , + J "> yz† Õ>~• lˆ yz *+

 {± ( )". +E4 Ɔ$ yz†p † t+ ‘y

 |}>~ 4 • “".

Paganin e[16]$ Ɔ š ¸¹º Ë ‰ É|
K

©¦, Ɔ šL %Ö 6,ˆ(L35µm) † ™ˆ ¯M   É| Z Ɔp yz† i ‘y+ Ä • lN,

šL 35µm+}, Ɔ j_>Ù 7!"  4þÿ+ Á

". ˆ Ɔ šL %Ö š" ˆ(N50µm) … ÆL ONr 0 + NP• lO &('}(flooding) ±,Ù ( )". + p ‰2ˆ Ɔ š& 40-50µm ¨4 j_>~

Â+ ªÐ".

˜
K Ɔ, ¸¹º+ 40% Õ“ ½ R¾ : 40µm š 4³g ‚ É| ÌÍ!Î". Fig. 11 h 

 ‹+ _m p Ɔ+ 6 n+ 0.6 Vù, 736 mA/

Fig. 10. Effect of the resistance layer to mass transport on the cell per- formance.

Fig. 11. Effect of the diffusion layer on the cell performance.

Pt loading=0.4 mg/cm, Pt/C=40 wt%, solvent=NBA, H₂/O₂=1/1 atm, and T=80^oC.

Fig. 12. Distribution of platinum and sulfur on the cross section of the electrodes analysed by EPMA.

cm² hbÅO, Ɔ+ à n$ 928 mA/cm² _m h

bN Ɔ j_  : 26% _m|} 'Å". PQ O  Û#4 É _m|}+ 5 Ɔ+ … /÷p _0

5& FI•  ð ( )".

Fig. 12 13 Ɔ à gW ‰ yz R³& ðZ!

J EPMA SEM tD n ´ˆ RÑ Â+". Fig. 12(a)  4>“  ‹+ Ɔ+ 6+ —˜Ã+ J yz† 4³  n yzÓAL —˜Ã+ bW g —˜Ã+ bWG w x ŠÁL h,-, Fig. 13(a) SEMtòQR yz† KR

 NèS". ^ Ɔ+ à n[Fig. 12(b)] —˜Ã+

™ˆ² wxŠÁL h,-, Fig. 13(b) ‹+ yz† j } TUQ @ ( )Å". + ‹$ pW;, Ɔ j_>~•

lˆ ½Ã+ bW yzÓAL l Z yz *+6+ 9

4.  

n o_ Ï o¡«+
 _m È É| ÌÍ!

 J +ŒŽ Ëp yzÀÁ o¡« É| ÌÍ!Î,-,

i Ï 0Ði ¡« tDg Ff RÑ©". +ŒŽ

yz†b Ë$ yz 9g ֕u 1/3 O, … +ŒŽ8  1/4$ yz† 3/4$  1 „p yz† ‡ˆ R³>Ù 7 q O _m hbÅ". ^ IPA& Dz   1 D «

tDˆ n† b +ŒŽ
+ Ä O, +ŒŽL yz ÈÒ /G lN 0 ‘¢ NP• ". . yz

+ VЕ “". + u NBA& Dz  µ+¶« tD

g yz ÀÁ& oˆ yz -… ÁL 5r n /

+ €LlO, yz -… t+ +ŒŽ }J
+ ÄZr (+U 44L |}lÅ". . ½Æ† É| Ì͘ p

½Ã+ J ½Æ† 4³ W yz† j_>~ˆ yz * + {± ( ) Y² Z[\ ½Ã+ †p yzà t+ ‘y þÿ Ï 01þÿ {± ( )â ð ( )Å".

+ ‹+ +ŒŽ H Ï R³& qiO NBA& Dz µ

+¶«, yz† o- ½Æ† 4Ó p H2/O₂=1/

1 atm, T=80^oC oì _m+ 0.6 V& ù,  7 928 mA/cm²& hb e n _m Á• |}>Ù ( )Å".

 

1. Lee, S. J. and Mukergee, S.: Electrochimica Acta, 43, 3693(1998).

2. Liu, R. and Her, W. H.: ibid, 139, 15(1992).

3. Verbrugge, M. W.: ibid, 139, 15(1992).

4. Uchida, M. and Aoyama, Y.: Journal of Electrochem. Soc., 142(12), 1443(1995).

5. Giorgi, L. and Antolini, E.: Electrochimica Acta, 43(24), 3675(1998).

6. Cheng, X. and Yi, B.: Journal of Power Sources, 79, 75(1999).

7. Ticianelli, E. A., Derouin C. R. and Srinivasan, S.: Journal of Elec- trochem. Soc., 135(9), 2209(1988).

. Wilson, M. S. and Gottesfeld, S.: Journal of Applied Electrochemis- try, 22, 1(1992).

9. Wilson, M. S., Valerio, J. A. and Gottesfeld, S.: Electrochimica Acta, 40(3), 355(1995).

10. Ticianelli, E. A., Derouin C. R. and Srinivasan, S.: Journal of Elec- troanal. Chem., 251, 275(1988).

11. Curtis, M. and Xianguo, L.: Journal of Power Sources, 77, 17(1999).

12. Uchida, M. and Aoyama, Y.: Journal of Electrochem. Soc., 142(2), 463(1995).

13. Lee, J. K., Ha, H. Y., Oh, I. H., Choi, H. J., Hong, S. A. and Chun, H. S.: Theories and Applications of Chem, Eng., 5(2), 3769(1999).

14. Wagner, N. and Schnurnberger, W.: Electrochimica Acta, 43(24), 3785 (1998).

15. Shim, J. P. Park, Y. S., Lee, H. K. and Lee, J. S.: Journal of Power Sources, 74, 151(1998).

16. Paganin, V. A. and Ticianelli, E. A.: Journal of Applied Electrochem- istry, 26, 297(1996).

Fig. 13. SEM photographs of the cross-sectional area of the MEAs.