Water electrolysis plateau in voltage reversal process for proton exchange membrane fuel cells

Abstract It is generally considered that the fuel cell is relatively safe in the region of the water electrolysis plateau (WEP) during voltage reversal. Therefore, the voltage-reversal tolerance of the cell is expected to be improved by extending the time of the WEP as much as possible. However, the cell is still likely to be damaged due to the extremely high anode potential. In this work, we have studied the WEP in the voltage reversal process for the first time. The results show that within the WEP, the performance of the cell is still declined, and the longer the time, the more the decline. This implies that the excessive pursuit of a long WEP will not truly help the improvement of voltage-reversal tolerance. In order to analyze the cause of performance degradation, the voltage losses induced by the electrochemically active surface area (ECSA), ohmic resistance have been studied. The calculated performance loss induced by decreased ECSA and increased ohmic losses account for only 8.43% of total loss (@50min, 1A·cm−2). Furthermore, the thinning of the anode catalyst layer and the obvious collapse of the microstructure rather than catalyst degradation itself is suspected to be the main cause of performance decay.