Durable Fuel Cell Electrode Design via Efficient Distribution of the Acidic Ionomer

Abstract

Proton Exchange Membrane (PEM) fuel cell based electrochemical energy conversion systems represent a cleaner alternative to replace diesel-based internal combustion engines for heavy-duty vehicle (HDV) applications. Enhanced durability of the fuel cell cathode is critical to decrease the total cost of ownership (TCO) of the vehicles. The fuel cell cathode comprises a platinum-based catalyst and perfluorosulfonic (PFSA) ionomer, which is needed to aid in proton conductivity, but it also creates an acidic environment for platinum dissolution. Here we report a new surface treatment process of the catalyst using an organic fluorocarbon molecule to efficiently distribute the ionomer and decrease the level of Pt dissolution. This allows for a ∼2-fold decrease in ionomer usage without compromising proton conductivity (∼25 mS cm^–1) due to the condensed, superprotonic ionomer pathways, thereby significantly improving platinum surface area retention. The structure of the electrode design and plausible reasons for the improved durability are discussed in detail here.