Investigation of real-time changes and recovery of proton exchange membrane fuel cell in voltage reversal

Highlights: • Carbon corrosion mainly occurs in the outlet of fuel cell during reversal. • Different regions have different performance degradation. • Part of the performance is recoverable after reversal. Hydrogen starvation at the anode of a proton exchange membrane fuel cell (PEMFC) causes cell voltage reversal followed by water electrolysis and carbon corrosion due to an increasing anode voltage. This study designed a set of online testing methods in different regions to take a closer look at the real-time changes of the internal current density and local temperature during the voltage reversal process. Mass spectrometer is used to test the anode tail gas to quantitatively characterize the progress of the reversal. Local Electrochemical Impedance Spectroscopy (Local EIS) and local Pt shedding before and after the reversal are innovatively performed to analyze the performance degradation of the fuel cell in different regions. In addition, the performance of fuel cell before and after the recovery process after the reversal is analyzed. Results show that the carbon corrosion in the outlet region of the reversal anode is the most severe, and the temperature at the inlet region due to the consumption of residual hydrogen is the highest. Compared with the inlet region, the Pt loss and High-Frequency Resistance (HFR) increase in the outlet is more serious. The process of performance recovery after reversal can make the current density distribution in fuel cell more uniform. Besides, the recovery process conducts a more positive impact on fuel cell outlet region than on inlet region. Data of mass spectrometer prove that water electrolysis and carbon corrosion disappear in the second reversal process, and then appear again in the third reversal process due to the performance recovery process.