Effect of Residual Water Contents in MEA on Performance Degradation Caused by Repeated Startup of Frozen Cell in PEFCs

The effect of residual water content in the MEA on performance degradation caused by repeated cold starts of a frozen cell at -30deg. C was investigated. The results indicated that when the residual water content in the MEA was low, a condition occurred in which both the diffusion and electrochemical activation capability of the ionomer in the catalyst layer of the cathode declined and degradation of cell performance increased compared with the high residual water content. Significant functional decay of the anode activation and polymer electrolyte membrane were not measured. Presumably, dry operation of the cell during startup from a frozen state caused the decline in ionomer performance, resulting in degraded cell performance.