Abstract: Self-humidifying fuel cell systems achieve automatic internal humidification through optimized materials, structures, and fuel cell control strategies. Due to their potentials for reducing system complexity and cost, they have become a prominent area of research. This review provides a comprehensive overview of the development of self-humidifying fuel cells in terms of materials, components, and systems and discusses potential applications of these cells in next-generation fuel cell systems. To enhance the performance of self-humidifying fuel cells, researchers are continuously exploring new technologies, materials, and methods including membrane design improvements, catalyst layer innovations, gas diffusion layer structure optimizations, membrane electrode assembly advancements, and flow field design enhancements along with system control optimizations. However, some challenges remain such as proton exchange membrane modifications, catalyst layer/microporous layer structure designs, bipolar plate flow-field innovations, and intelligent controls. Additionally, future directions are proposed that comprise machine learning-assisted material development, optimization of additive and catalyst compatibility, and dynamic simulation and fault prediction for system analysis. This review not only summarizes the main research directions highlighting recent progress in self-humidifying fuel cell technology, but also addresses technical problems faced during practical implementation of this technology. It is highly significant in clarifying the strategic position held by self-humidifying fuel cell technology and indicating frontier areas for further research and innovation.

Key words: PEM fuel cells, Self-humidifying, Membrane electrode assembly, Flow field design, Intelligent control strategy