Optimization on Composition and Structure of Catalyst Layer for High-Temperature Polymer Electrolyte Membrane Fuel Cells

Abstract High-temperature polymer membrane fuel cells (HT-PEMFCs) are considered the trend of PEMFC future development due to their accelerated electrochemical reaction kinetics, simplified water/thermal management, and improved tolerance to impurities (CO). As the core part of the membrane electrode assembly in HT-PEMFCs, the catalyst layer significantly affects the cost, performance, and lifetime of HT-PEMFCs. However, platinum (Pt) catalyst degradation and carbon corrosion are apparently accelerated because of the high-temperature and acid environment in HT-PEMFC. Moreover, the loss of phosphoric acid (PA) that serves as the proton conductor is observed after long-term operation. In addition, the adsorption of phosphate on the Pt surface leads to poor Pt utilization. Thus, high cost and fast performance decay must be addressed to achieve better commercialization of HT-PEMFC. Optimizing the composition and structure of the catalyst layer is demonstrated as an effective strategy to resolve these problems. In this review, we first summarize the latest progress in the optimization of the catalyst layer composition for HT-PEMFC, including catalysts, binders, electrolytes (PAs), and additives. Thereafter, the structural characteristics of the catalyst layer are introduced, and the optimization strategies are reviewed. Finally, the current challenges and research perspectives of the catalyst layer in HT-PEMFC are discussed.