Bridging ink formulation and proton exchange membrane fuel cell performance: Deciphering the role of catalyst ink composition in regulating ionomer behaviors and aggregates/agglomerates structures for high performance cell design

Proton Exchange Membrane Fuel Cell (PEMFC) catalyst inks' multi-scale structures are crucial determinants of electrode performance, while the composition of the inks plays a vital role in optimizing electrode design by regulating ionomer behavior and catalyst aggregation/agglomeration structures. Our work investigates the interaction mechanisms between ionomer dynamics and solid particle structures in catalyst inks, offering a comprehensive overview of recent research advancements in PEMFC catalyst ink. Initially, grounded in colloidal theoretical models, the applicability and limitations of classical DLVO theory and its extended model (xDLVO) in characterizing the complex interactions among ink components—such as van der Waals forces, electrostatic interactions, and ionomer adsorption effects—are discussed. Subsequently, advanced characterization techniques suitable for high-concentration opaque inks are reviewed, including scattering methods, rheological test, and cryo-electron microscopy, highlighting the importance of integrating multiple techniques to elucidate ink microstructures. Additionally, focusing on the four key parameters of ink formulation—catalyst type, I/C ratio, dispersion solvent, and solid content—this study provides an in-depth analysis of their regulatory effects on ionomer behavior, free ionomer self-assembly morphology, and catalyst aggregate/agglomerate structures. By integrating theoretical models, characterization methods, and experimental observations, we propose an advanced, multi-stage AI framework to accelerate the optimization of complex PEMFC catalyst ink formulations and establish the structure-function relationships among ink components, microstructures, and cell performance. • Analyzed particle interaction energy based on (x)DLVO theory to define an optimal ink state, offering guidance for optimizing PEMFC inks and highlighting current model shortcomings. • Systematically linked ink formulation to aggregate/agglomerate structure and ionomer adsorption behavior, establishing a direct, end-to-end connection to cell performance. • Underscore the critical role of variations in ink solid content on the properties of its components and highlights the current paucity of research on how solid content affects both ink behavior and fuel cell performance. • Proposing a multi-stage AI-aided framework to accelerate the optimization of complex, coupled ink systems—a methodology applicable to next-generation energy materials.