Materials innovations for flexible and wearable PEM fuel cells: From proton exchange membranes to stretchable electrodes

Flexible and wearable proton exchange membrane fuel cells (F-PEMFCs) are emerging as promising hydrogen-based power sources for next-generation portable electronics devices. Their successful implementation requires materials providing high electrochemical performance, mechanical compliance, durability under repeated deformation. This review critically discusses recent advances in material innovations for wearable PEMFCs, covering proton exchange membranes, hydrocarbon and nanocomposite membranes, stretchable and self-healing electrolytes, flexible electrodes, gas diffusion layers, current collectors, and device architectures. Nanocomposite membranes incorporating graphene oxide, MXenes, SiO 2 , TiO 2 , and nanocellulose show improved water retention, reduced crossover, while stretchable and self-healing polymer networks offer new opportunities for mechanically resilient F-PEMFCs. Flexible electrodes based on carbon nanotubes, graphene, conductive polymers, and hybrid catalyst architectures can retain more than 90% of their conductivity under bending, although catalyst-layer delamination and interfacial degradation remain key challenges. This review identifies current limitations and provides a roadmap toward efficient, and scalable wearable hydrogen energy technologies.