Cathode Catalyst Layer Design and Optimization for Portable Power Applications Using Non-Precious Metal Catalysts

Abstract

In recent years, the inherent activity of M/N/C (M=Fe, Co, or Mn) non precious metal catalyst (NPMCs) has advanced to a stage where these catalysts can be considered as potential alternatives to Pt/Pt-alloy catalysts for certain applications(1-4), provided stability/durability can be improved(5). Due to these achievements, NPMCs have advanced beyond purely rotating disc electrode (RDE) studies, and are now ready to be thoroughly evaluated at the membrane electrode assembly (MEA) level. While previous work has looked at in-situ MEA evaluation of NPMCs, few of these studies have investigated maximizing performance through rational design of the cathode catalyst layer (CCL). However, recent work by Serov et al. (3) has highlighted the importance of CCL design parameters in maximizing the performance of NPMC-based CCLs. The significant difference in CCL layer thickness of NPMC-based CCLs vs. conventional Pt/C CCLs means any optimization used for conventional Pt/C CCLs will likely not apply to these novel NPMC CCLs. This provides the research community with significant opportunity in this largely unexplored area. In this work, we will present some of our recent findings on designing and optimizing NPMC-based CCLs for portable power and backup power applications. The NPMC used in this work is developed by Nisshinbo Holdings, and has demonstrated world-leading performance in laboratory scale (50 cm2) MEA testing. After a brief discussion on the synthesis of this NPMC, the results of optimizing the CCL design (e.g. ionomer type/content) will be shown. Performance data recently obtained under conditions relevant for portable power/backup power will be presented and compared against product requirements. Acknowledgements The authors thank Alan Young for many helpful discussions,