In PAFC, the degradation on cathode electrode caused by carbon corrosion[l], platinum dissolution[2] and growth[3] is especially severe. An acceleration test is a good technique for evaluating the degradation of elcctrode performance, because it does not need long time. Coleman et al[4] used thermal cycling and on-off cycling as an acceleration test Song et al[5] showed that hydrogen shortage decreased the elcctrode performance more rapidly than that of air shortage in gas shortage test Honji et al[6] reported that the rate of coarsening of Pt particle is rapid in open circuit potential and this is one of major causes on the performance degradation of electrode. The cathode performance has been studied by using acid absorption, acceleration and ac-impedance measurements as functions of the polytetrafluoroethylene(PTFE) contents and sintering temperatures of the electrode.

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