Research progress of catalyst layer and interlayer interface structures in membrane electrode assembly (MEA) for proton exchange membrane fuel cell (PEMFC) system

Stricter requirements for MEA structure have to be met in order to realize the rapid commercialization and marketization of polymer electrolyte membrane fuel cell (PEMFC). Optimization and design of catalyst layer and interlayer interface structures is helpful to increase the utilization of Pt, reduce mass transfer loss and realize the high-performance output of membrane electrode assembly (MEA) with Low-Pt loading. Herein, this paper reviews recent developments of catalyst layer and GDL/PEM/CL interlayer interface structures in MEA. The evolution process from conventional catalyst layer to gradient and ordered catalyst layer is presented. The interactions among Pt-based catalysts, carbon supports, ionomers and solvent in catalyst ink are comprehensively discussed, and its influence on the structure of conventional porous catalyst layer are analyzed. Moreover, this paper discusses the gradient distribution law of ionomer, Pt loading and hydrophilicity/hydrophobicity in the catalyst layer, and introduces the design and preparation strategies of ordered electrode based on nanoarray structure. In addition, novel approaches to engineer the PEM/CL interface are schematically summarized as engineering surface-patterned membranes, direct deposited membrane technology, and porous membrane design. GDL/CL interface gap lead to liquid water pooling in the interfacial void space and reduces contact area, and the impact of GDL/CL interface characteristics on contact resistance and internal mass transfer in MEA are also taken into account. This review highlights the importance of combination design strategy of catalyst layer bulk structure and interlayer structure, and gives a brief discussion about future development prospects.