| CPC H01M 8/04701 (2013.01) [H01M 4/9075 (2013.01); H01M 8/04753 (2013.01); H01M 8/04835 (2013.01); H01M 8/1004 (2013.01); H01M 8/1023 (2013.01); H01M 2008/1095 (2013.01); H01M 2300/0082 (2013.01)] | 13 Claims | 

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               1. A method of operating a fuel cell comprising a membrane electrode assembly containing an electrolyte membrane, catalyst layers, and gas diffusion layers, the method including, in a single step, (a) setting an operating temperature of the fuel cell at 100° C. or more, and (b) concurrently setting a relative humidity of a supply gas to be supplied to the fuel cell to 70% or more and a back pressure of the supply gas to 330 kPa or more. 
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