알칼리 연료전지용 라니니켈 수소극에서 촉매층의 구조와 촉매 Loading 량의 영향

조장호; 김형진; 문세기

HWAHAK KONGHAK, Vol.34, No.5, 629-635, October, 1996

Export Citation

알칼리 연료전지용 라니니켈 수소극에서 촉매층의 구조와 촉매 Loading 량의 영향

Structure of Catalyst Layer and Effect of Catalyst Loading In Raney Nickel Hydrogen Electrodes for Alkaline Fuel Cells

조장호, 김형진, 문세기

초록

성능과 경제적인 측면에서 가장 우수한 연료전지 중의 하나인 알칼리형 연료전지에서는 백금과 같은 귀금속 촉매 대신 비귀금속 촉매가 사용될 수 있다. 라니니켈은 이러한 알칼리형 연료전지 시스템에 적합한 비귀금속 촉매로 잘 알려져 있다. 본 연구에서는 촉매 loading량이 분극특성에 미치는 영향과 라니니켈 수소극의 촉매층 구조에 대해 알아보았다. 이 연구를 통해, 촉매 loading량이 105mg cat./cm²일 때 100mV 과전압에서 전류밀도 270mA/cm²의 전극 성능을 얻었다. 본 연구의 결과에 의하면, 촉매 loading 량을 증가시킴에 따라 전극의 분극저항은 일정값으로 수렴하였으며, 촉매 이용도는 감소하였다. 또한, 한계전류밀도는 촉매 loading량에 선형적으로 비례하였고, limiting mass activity는 촉매 loading량에 대해 독립적이었다. 이러한 촉매 loading량의 영향과 촉매층 구조의 분석으로부터, 이 연구에 사용된 촉매의 미세기공은 OH^-의 확산에 대한 저항이 큰 구조를 갖고 있는 반면, 본 연구를 통해 제작된 촉매층의 거대기공은 기상확산에 대한 저항이 거의 없는 구조를 갖고 있는 것을 알 수 있었다.

In alkaline fuel cell, which is one of most excellent fuel cells in performance and economical aspects, non-noble metal catalysts can be used instead of no- ble metal catalysts like Pt. Raney Nickel is well known as a suitable non- noble metal catalyst for this fuel cell system. In the present work, we investi- gated the effects of the catalyst loading on polarization characteristics and the structure of the catalyst layer of Raney nickel hydrogen electrodes. Through this work, we obtained the electrode performance of current density of 270mA /cm² at overpotential of 100mV when the electrode loaded with a 105mg/cm² catalyst. According to the results of the present study, with increasing the catalyst loading, the polarization resistance of the electrode converged to constant value and the degree of the catalyst utilization decreased. Also, limiting current density was linearly proportional to the catalyst loading and limiting mass activity was independent of catalyst loading. From these effects of the catalyst loading and the analysis of structure of the catalyst layer, it was found that the micropore of the catalyst used for this study had the structure of which resistance for the OH^- diffusion is large, on the other hand, the macropore of the catalyst layers prepared through this work had structure of which resistance for gas-phase diffusion is almost absent.

Keywords:Alkaline Fuel Cell;Raney Nickel;Hydrogen Electode;Catalyst Layer;Limiting Current Density

[References]

Linden D, "Handbook of Batteries and Fuel Cells," McGraw-Hill, New York (1984)
Appleby AJ, Foulkes FR, "Fuel Cell Handbook," Van Nostrand Reinhold, New York (1989)
Gulzow E, Schulzc M, Steinhilher G, Blowin K, "Program and Abstracts: 1994 Fuel Cell Seminar," San Diego, U.S.A. (1994)
Mund K, Ritcher G, Sturm F, J. Electrochem. Soc., 124, 1 (1977)
Kenjo T, J. Electrochem. Soc., 132, 383 (1985)
Kenjo T, Bull. Chem. Soc. Jpn., 54, 2553 (1981)
Jenseit W, Khalil A, Wendt H, J. Appl. Electrochem., 20, 893 (1990)
Wendt H, "Electrochemical Hydrogen Technologies," Elsevier Science, Amsterdam (1990)
Jo JH, Kim HJ, Lee JS, "Abstracts of '95 Asian Conference on Electrochemistry," Osaka, Japan (1995)
Kenjo T, J. Electrochem. Soc., 132, 1583 (1985)
Cutlip MB, Electrochim. Acta, 20, 767 (1975)
Bjornbom P, Electrochim. Acta, 32, 115 (1987)
Bockris JOM, Srinivasan S, "Fuel Cells: Their Electrochemistry," McGraw-Hill, New York (1969)
Kimble MC, White RE, J. Electrochem. Soc., 138, 3370 (1991)
Strasser K, J. Power Sources, 29, 149 (1990)
Newman JS, "Electrochemical Systems," Prentice-Hall, Inc., Englewood Cliffs, NJ (1988)
Kinoshita K, "Carbon: Electrochemical andPhysicochemical Properties," John Wiley & Sons, Inc., New York (1988)
Kenjo T, Denki Kagaku, 53, 957 (1985)

[Referenced By]

[1] Linden D, "Handbook of Batteries and Fuel Cells," McGraw-Hill, New York (1984)

[2] Appleby AJ, Foulkes FR, "Fuel Cell Handbook," Van Nostrand Reinhold, New York (1989)

[3] Gulzow E, Schulzc M, Steinhilher G, Blowin K, "Program and Abstracts: 1994 Fuel Cell Seminar," San Diego, U.S.A. (1994)

[4] Mund K, Ritcher G, Sturm F, J. Electrochem. Soc., 124, 1 (1977)

[5] Kenjo T, J. Electrochem. Soc., 132, 383 (1985)

[6] Kenjo T, Bull. Chem. Soc. Jpn., 54, 2553 (1981)

[7] Jenseit W, Khalil A, Wendt H, J. Appl. Electrochem., 20, 893 (1990)

[8] Wendt H, "Electrochemical Hydrogen Technologies," Elsevier Science, Amsterdam (1990)

[9] Jo JH, Kim HJ, Lee JS, "Abstracts of '95 Asian Conference on Electrochemistry," Osaka, Japan (1995)

[10] Kenjo T, J. Electrochem. Soc., 132, 1583 (1985)

[11] Cutlip MB, Electrochim. Acta, 20, 767 (1975)

[12] Bjornbom P, Electrochim. Acta, 32, 115 (1987)

[13] Bockris JOM, Srinivasan S, "Fuel Cells: Their Electrochemistry," McGraw-Hill, New York (1969)

[14] Kimble MC, White RE, J. Electrochem. Soc., 138, 3370 (1991)

[15] Strasser K, J. Power Sources, 29, 149 (1990)

[16] Newman JS, "Electrochemical Systems," Prentice-Hall, Inc., Englewood Cliffs, NJ (1988)

[17] Kinoshita K, "Carbon: Electrochemical andPhysicochemical Properties," John Wiley & Sons, Inc., New York (1988)

[18] Kenjo T, Denki Kagaku, 53, 957 (1985)