Formation mechanism and morphology control of cracks in PEMFC catalyst layer during fabrication process: A review

The catalyst layer (CL) is susceptible to cracking during the fabrication process, which presents challenges to the performance and durability of proton exchange membrane fuel cell (PEMFC). This review systematically cascades mechanisms, factors, methods, and applications to provide the first all-encompassing analysis of CL cracking. To construct a research framework, this review comprehensively analyzes the formation mechanism of CL cracks and outlines various approaches for crack morphology optimization. By combining linear elastic fracture mechanics (LEFM) and related research on the drying of colloidal films, the causes of CL cracks can be attributed to structural defects and stress concentrations. On this basis, the means of crack regulation are illustrated from the perspective of ink components and drying conditions. In the end, the impact of cracks on the performance of CL is analyzed and some novel crack inhibition techniques are introduced. Although this review organizes and summarizes the results of related research, there is still a gap in the field of CL crack research. This is evidenced by the lack of a more accurate mechanism for CL crack formation, the unclarity on the effect of crack morphology on CL performance, and the fact that methods to regulate cracking by changing the drying pattern have yet to be further investigated.