Electrode pore structure degradation in alkaline polymer electrolyte fuel cells

Poor durability is a major obstacle in the development of practical alkaline polymer electrolyte fuel cells (APEFCs). Understanding the degradation mechanisms of the APEFCs is essential for designing improvement strategies. Here we use quaternary ammonia poly N-methyl-piperidine-co-p-terphenyl (QAPPT) as the alkaline polymer electrolytes (APE) and ionomer in a model APEFC and carry out cell-level durability tests. The evolution in Pt/C catalysts, membrane, ionomer, and pore structure are investigated using a suite of complementary characterization techniques. The results show that the pore structure of the APEFC electrode deteriorated seriously, which hinders water and gas transport and plays an important role in reducing the overall performance. The heterogeneous evolution of the pore structure is linked to the decomposition of QAPPT ionomer and the loss of binding capability. This work points to new directions in improving the durability of APEFCs.