Long life expectancy of alkaline fuel cells in hybrid vehicles
The alkaline Hydrogen-Air fuel cell system with circulating KOH-electrolyte and low-cost catalyzed carbon electrodes has a simple design and a good efficiency (high voltage). With new electrodes current densities of 200 to 300 mA/cm 2 are expected with air operation at 80 o C. The Austin A-40 City Car Hybrid vehicle which K. Kordesch operated on public roads for 3 years, demonstrated already in the early 1970s that the useful life of the alkaline system with circulating electrolyte can be increased by completely shutting down the fuel cell part of an AFC-lead-acid battery hybrid system. In this way, only the operating hours during driving time of the vehicle are counting and the electrode deterioration processes going on at open circuit (e.g. carbon oxidation, deep wetting of the electrode interface, parasitic current phenomena, etc.) are reduced. Like with a combustion engine, 3000--4000 actual operating hours are what are required for 200.000 km driving. The stacks, which use low-cost modular cell units, could be replaced after that. Another objective is to lower the fuel cell system cost on a mass production scale to the range of $ 100 to 150 per kW, which is then competitive with car engines, which cost only $ 50 to 75 per kW. No other fuel cell system could even approach such cost estimates. For reasons demanded by space requirements the historic development of AFC's shifted to matrix AFC systems. However, for terrestrial applications the use of circulation systems is more advantageous for thermal and water management. Jet pumps are usable for providing a load-dependent gas circulation. The exchangeability of the KOH makes it possible to operate on air with a less than complete removal of the CO{sub 2}. Cell reversal of series-connected cells, a frequent failure mode during shut-down and starting, is one of the main causes for the short life of electrodes in a high voltage stack. It can be prevented by a parallel, potential providing circuit.
- Research Organization:
- Technical University Graz (AT)
- OSTI ID:
- 20000174
- Resource Relation:
- Conference: 33rd Intersociety Energy Conversion Engineering Conference, Colorado Springs, CO (US), 08/02/1998--08/06/1998; Other Information: 1 CD-ROM. Operating system required: Windows 3.x; Windows 95/NT; Macintosh; UNIX. All systems need 2X CD-ROM drive., PBD: 1998; Related Information: In: Proceedings of the 33. intersociety energy conversion engineering conference, by Anghaie, S. [ed.], [2800] pages.
- Country of Publication:
- United States
- Language:
- English
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