Proton-exchange membrane fuel cells kinetics

J. Srmivason, et al., "High Energy Efficiency and High Power Density Proton Exchange Membrane Fuel Cells - Electrode Kinetics and Mass Transport," Journal of Power Sources, p. 36, 1991. 

DMFCs and direct ethanol fuel cells (DEFCs) are based on the proton exchange membrane fuel cell (PEM FC), where hydrogen is replaced by the alcohol, so that both the principles of the PEMFC and the direct alcohol fuel cell (DAFC), in which the alcohol reacts directly at the fuel cell anode without any reforming process, will be discussed in this chapter. Then, because of the low operating temperatures of these fuel cells working in an acidic environment (due to the protonic membrane), the activation of the alcohol oxidation by convenient catalysts (usually containing platinum) is still a severe problem, which will be discussed in the context of electrocatalysis. One way to overcome this problem is to use an alkaline membrane (conducting, e.g., by the hydroxyl anion, OH ), in which medium the kinetics of the electrochemical reactions involved are faster than in an acidic medium, and then to develop the solid alkaline membrane fuel cell (SAMFC). 

Fig. 13.27. Potential vs. current density plots for state-of-the-art fuel cells, o, proton exchange membrane fuel cell , solid oxide fuel cell , pressurized phosphonic acid fuel cell (PAFC) a, direct methanol fuel cell, direct methanol PAFC , alkaline fuel cell. (Reprinted from M. A. Parthasarathy, S. Srinivasan, and A. J. Appleby, Electrode Kinetics of Oxygen Reduction at Carbon-Supported and Un-supported Platinum Microcrystal-lite/Nafion Interfaces, J. Electroanalytical Chem. 339 101-121, copyright 1992, p. 103, Fig. 1, with permission from Elsevier Science.)...

Mukerjee S, Siinivasan S, Appleby AJ (1993) Effect of sputtered film of platinum on low platinum loading electrodes on electrode kinetics of oxygen reduction in proton exchange membrane fuel cell. Electrochim Acta 38(12) 1661-9... 

Alkaline fuel cells have numerous advantages over proton exchange membrane fuel cells on both cathode kinetics and ohmic polarization [115]. 

Neyerlin, K.C., Singh, A., and Chu, D. (2008) Kinetic characterization of a Pt-Ni/C catalyst with a phosphoric acid doped PBI membrane in a proton exchange membrane fuel cell. J. Power Sources, 176, 112-117. 

Srinivasan S, Velew OA, Parthasarathy A, Manko DJ, Appleby AJ. High energy efficiency and high power density proton exchange membrane fuel cells - electrode kinetics and mass transport. J Power Sources 1991 36 299-320. 

Huth A, Schaar B, Oekermann T (2009) A proton pump concept for the investigation of proton transport and anode kinetics in proton exchange membrane fuel cells. Electrochim Acta 54 2774-2780... 

High-temperature proton exchange membrane fuel cells (HT-PEM fuel cells), which use modified perfluorosulfonic acid (PFSA) polymers [1—3] or acid-base polymers as membranes [4—8], usually operate at temperatures from 90 to 200 °C with low or no humidity. The development of HT-PEM fuel cells has been pursued worldwide to solve some of the problems associated with current low-temperature PEM fuel cells (LT-PEM fuel cells, usually operated at <90 °C) these include sluggish electrode kinetics, low tolerance for contaminants (e.g. carbon monoxide (CO)), and complicated water and heat management [4,5]. However, operating a PEM fuel cell at >90 °C also accelerates degradation of the fuel cell components, especially the membranes and electrocatalysts [8]. 

Recent developments in AAEMs have opened up the possibiUty of an alkaline analog of the acidic solid polymer electrolyte fuel cell. This could utilize the benefits of the alkaline cathode kinetics and at the same time eradicate the disadvantages of using an aqueous electrolyte. As the AAEM is also a polymer electrolyte membrane (sometimes abbreviated as PEM), some clarity in abbreviations is required. In this chapter, PEM refers only to the proton exchange membrane fuel cells (acidic), AAEM refers to the anion exchange membrane H2/O2 fuel cells, and AFC exclusively refers to the aqueous electrolyte alkaline H2/O2 fuel cells. Anion exchange membranes are also employed in alkaline direct alcohol fuel cells, discussion of which will refer to them as ADMFC/ADEFC (methanol/ ethanol). 

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