Degradation-Mitigating Composite Membrane That Exceeds a 1 W cm-2Power Density of a Polymer Electrolyte Membrane Fuel Cell Operating under Dry Conditions

Abstract

One material dominating the polymer electrolyte membrane (PEM) technologies is the Nafion membrane due to its excellent properties in ion conduction and chemical stability. That notwithstanding, its reduced performance under low humidity and rapid degradation limit its wide application. Here, a scalable and straightforward method is reported to form cerium titanate nanoparticles dispersed on smooth carbon nanofibers (CTO/CTO@CNF). We demonstrate that, when CTO/CTO@CNF was incorporated as a degradation-mitigating additive to the Nafion ionomer, it significantly reduced the membrane degradation by up to 2 orders of magnitude and durability over 400 h, surpassing those features of the state-of-the-art Nafion-211 membrane. The composite membrane in a PEM fuel cell operated under low relative humidity (RH) resulted in the highest power output (1219 mW cm-2) and current density (3986 mA cm-2) to the authors' knowledge. Fluoride emission rate (FER) results of 400 h of open-circuit voltage hold validates the rationale of merging Nafion membranes with this degradation-mitigating additive in witnessing a path to possible life span extension of the fuel cell membrane. © 2021 American Chemical Society.