Performance deterioration and recovery in high-temperature polymer electrolyte membrane fuel cells: Effects of deliquescence of phosphoric acid

Abstract Phosphoric acid (PA)-doped polybenzimidazole (PBI) membranes used in high-temperature polymer electrolyte membrane fuel cells (HT-PEMFCs) have high proton conductivity, and excellent mechanical and thermal stability. However, the deliquescence of PA leads to performance deterioration in humid atmosphere. The performance degradation upon exposure of the PA-doped membrane to humidity and the changes in the performance as a function of the PA loading in the electrodes are investigated. The performance of the HT-PEMFC employing the humidity-exposed membrane declines by 74.1% compared to that of the pristine membrane due to ineffective formation of the three-phase boundary. Loading a small amount of PA into the electrode induces drastic performance recovery with a decrease in the charge transfer resistance, especially at the anode. PA-dosing of both electrodes produces the best performance recovery, exceeding that of the pristine counterparts. This is a simple and effective method of recovering the performance of HT-PEMFCs after humidity-related deterioration.