Tailoring Electrocatalyst–Ionomer Coupling for High-Performance PEM Fuel Cells via Optimizing Long/Short-Range Interactions

Dispersing solvent is an exclusive mediator to tailor solvent–electrocatalyst–ionomer coupling dynamics and further proton exchange membrane fuel cell (PEMFCs) performance. On one hand, this coupling tailors the nucleation and subsequent growth dynamics of electrocatalyst–ionomer aggregates, determining the diffusion pathway as well as electron/proton-conduction continuity. On the other hand, this coupling controls the accessibility and local structure of the triple-phase boundary, affecting the amounts of active centers and local O2 transport resistance. Therefore, unveiling the relationship between ink composition and electrocatalyst–ionomer coupling at short/long range improves electrochemical reaction dynamics and facilitates construction of high-performance membrane electrode assemblies (MEAs). In this review, the regulation mechanism of solvent–electrocatalyst–ionomer coupling and performance enhancement are systematically summarized. Also, the composition effect including the physiochemical property of solvents, molecular morphology of ionomers, and structure of electrocatalysts is sufficiently unveiled by analyzing oxygen-transport impedance and accessibility of triple-phase boundary. Meanwhile, the design principle for structurally matching solvents, ionomers, and electrocatalysts is also presented on the basis of short-range and long-range interactions. This review provides a guideline for constructing high-performance MEA via electrocatalyst–ionomer–solvent coupling modulation.