Modifying the Electrocatalyst-Ionomer Interface via Sulfonated Poly(ionic liquid) Block Copolymers to Enable High-Performance Polymer Electrolyte Fuel Cells

Yawei Li; Tim Van Cleve; Rui Sun; Ramchandra Gawas; Guanxiong Wang; Maureen Tang; Yossef A Elabd; Joshua Snyder; K C Neyerlin

doi:10.1021/acsenergylett.0c00532

Modifying the Electrocatalyst-Ionomer Interface via Sulfonated Poly(ionic liquid) Block Copolymers to Enable High-Performance Polymer Electrolyte Fuel Cells

ACS Energy Lett. 2020 Apr 29;5(6):1726-1731. doi: 10.1021/acsenergylett.0c00532. eCollection 2020 Jun 12.

Authors

Yawei Li¹, Tim Van Cleve¹, Rui Sun², Ramchandra Gawas³, Guanxiong Wang¹, Maureen Tang³, Yossef A Elabd², Joshua Snyder³, K C Neyerlin¹

Affiliations

¹ Chemistry and Nanoscience Center, National Renewable Energy Laboratory, Golden, Colorado 80401, United States.
² Department of Chemical Engineering, Texas A&M University, College Station, Texas 77843, United States.
³ Department of Chemical and Biological Engineering, Drexel University, Philadelphia, Pennsylvania 19104, United States.

Abstract

Polymer electrolyte membrane fuel cell (PEMFC) electrodes with a 0.07 mg_Pt cm^-2 Pt/Vulcan electrocatalyst loading, containing only a sulfonated poly(ionic liquid) block copolymer (SPILBCP) ionomer, were fabricated and achieved a ca. 2× enhancement of kinetic performance through the suppression of Pt surface oxidation. However, SPILBCP electrodes lost over 70% of their electrochemical active area at 30% RH because of poor ionomer network connectivity. To combat these effects, electrodes made with a mix of Nafion/SPILBCP ionomers were developed. Mixed Nafion/SPILBCP electrodes resulted in a substantial improvement in MEA performance across the kinetic and mass transport-limited regions. Notably, this is the first time that specific activity values determined from an MEA were observed to be on par with prior half-cell results for Nafion-free Pt/Vulcan systems. These findings present a prospective strategy to improve the overall performance of MEAs fabricated with surface accessible electrocatalysts, providing a pathway to tailor the local electrocatalyst/ionomer interface.