Performance Degradation and Strategy Optimization of PEMFCs Under Subfreezing Temperature

Abstract:

Polarization curve, electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and segmented cell techniques were adopted to investigate the performance degradation of proton exchange membrane fuel cell (PEMFC) during storage and startup processes under subfreezing temperatures(<0 ℃). The experimental results indicate that freeze/thaw cycles without gas purge during shutdown process will increase the polarization resistance and deteriorate the current density output of PEMFC. In addition, the electrochemical surface area (ECSA) of catalyst layer decreased and the uniformity of current density distribution of PEMFC worsened, which deteriorates the overall durability of PEMFC. Based on the optimized twicepurge strategy, the efficiency of residual water removing was enhanced with less gas consumption. With the aid of circulating coolant heating solution, the cold start of single cell from -30 ℃ was successfully achieved within 340 s.

Key words:proton exchange membrane fuel cell (PEMFC); cold start; current density distribution; performance degradation; strategy optimization