Comparison of MEA Degradation through FCV Actual Driving Test and Load-Cycle Durability Test

The degradation of a membrane electrode assembly (MEA) after an actual driving test was analyzed, and its mechanism was compared with that of a load-cycle durability test in a laboratory. MEA samples were extracted from an FC stack of a Toyota MIRAI 2014th model which had been operated in actual driving of 200,000 km for approximately 6000 h. The degradation distribution across the MEA plane was found to be insignificant. The electrolyte membrane did not show significant degradation affecting its properties following the durability tests. The MEA performance degradation is primarily attributed to the deterioration of the catalyst activity and oxygen transport properties in the catalyst layer, which is mainly caused by catalyst coarsening. The degradation was well simulated by the NEDO load-cycle durability test of 30,000 cycles. The evaluation results are applicable to validation of AST protocols and model-simulation of MEA degradation.