Kinetics and Kinetically Limited Performance in PEMFCs and DMFCs with State-of-the-Art Catalysts
Over the past 10 years, extensive R&D efforts to optimize H2/air-fed proton exchange membrane fuel cell (PEMFC) performance resulted in power densities near 1 W/cm2 at ≈0.6 V and much reduced MEA (membrane electrode assembly) platinum loadings of ≈0.45 mgPt/cm2 MEA. These accomplishments were largely driven by the implementation of thin membranes (≈25 μm), highly conductive bipolar plate materials/coatings, and empirical improvements in electrode design. In order to close the remaining performance gap for automotive applications, it is critical to quantify the various voltage losses in state-of-the-art H2/air MEAs, as this will enable more targeted future MEA materials and design development.
Similarly, much progress has been made in materials and engineering design of direct methanol fuel cells (DMFCs), and it is instrumental to deconvolute materials related losses (catalyst activity and ohmic resistances) from mass-transport related losses. This analysis will again enable the determination of performance gains which can be made by either MEA materials or MEA design improvements.
Thus, this paper will review the activity of currently known anode and cathode catalysts in H2/air PEMFCs and DMFCS. Using these well-known kinetics, an analysis of the various voltage loss contributions will be conducted in order to determine the impact of mass transport losses and proton conduction losses, with the hope of being able to provide a clear focus on future development needs with regards to materials development and MEA engineering optimization.
KeywordsFuel Cell Oxygen Reduction Reaction Proton Exchange Membrane Fuel Cell Direct Methanol Fuel Cell Exchange Current Density
Unable to display preview. Download preview PDF.
- 2.P. Piela and P. Zelenay, Researchers Redefine The DMFC Roadmap, The Fuel Cell Review Aug./Sept., 17 (2004).Google Scholar
- 3.H.A. Gasteiger, W. Gu, R. Makharia, M.F. Mathias, and B. Sompalli, ‘Beginning-of-Life MEA performance-efficiency loss contributions’, in: Handbook of Fuel Cells: Fundamentals, Technology, and Applications, edited by W. Vielstich, A. Lamm, and H.A. Gasteiger (Wiley, Chichester, 2003), vol. 3, pp. 593-610.Google Scholar
- 8.J.S. Newman, Electrochemical Systems (Prentice Hall, Englewood Cliffs, NJ, 1991).Google Scholar
- 10.D. Thompsett, ‘Pt Alloys as Oxygen Reduction Catalysts’, in: Handbook of Fuel Cell, edited by W. Vielstich, A. Lamm, and H.A. Gasteiger (Wiley, NY, 2003), vol. 3, pp. 467-480.Google Scholar
- 19.M.P. Hogarth and T.R. Ralph, Catalysis for Low Temperature Fuel Cells, Part 111: Challenges for the Direct Methanol Fuel Cell, Platinum Metals Rev. 46, 146 (2002).Google Scholar
- 23.H.A. Gasteiger and J. Garche, ‘Fuel Cells’, in: Handbook of Heterogeneous Catalysis (2nd edn), edited by G. Ertl, H. Knözinger, F. Schüth, and J. Weitkamp (Wiley-VCH, Weinheim, Germany, 2008), in press.Google Scholar
- 26.S.S. Sandhu, R.O. Crowther, S.C. Krishnan, and J.P. Fellner, Direct Methanol Polymer Electrolyte Fuel Cell Modeling: Reversible Open-Circuit Voltage and Species Flux Equations, Electrochim. Acta 48, 2295 (2003).Google Scholar
- 27.M.F. Mathias, R. Makharia, H.A. Gasteiger, J.J. Conley, T.J. Fuller, C.J. Gittleman, S.S. Kocha, D.P. Miller, C.K. Mittelsteadt, T. Xie, S.G. Yan, and P.T. Yu, Two Fuel Cell Cars in Every Garage? Interface (The Electrochemical Society, 2005), 14, pp. 24-35.Google Scholar