Advances in Short‐Side‐Chain Perfluorosulfonic Acid Electrolytes for Proton Exchange Membrane Fuel Cells

ABSTRACT This review discusses electrochemical energy systems with a focus on proton exchange membrane fuel cells (PEMFCs), highlighting the key role of proton exchange membranes (PEMs) in fuel cell performance. Among various PEM materials, Perfluorosulfonic acid (PFSA) ionomers are widely used due to their excellent chemical and proton‐conducting properties. The present review places special emphasis on short‐side‐chain (SSC) PFSA ionomers, which have gained attention over conventional long‐side‐chain (LSC) types like Nafion. SSC‐PFSAs offer improved thermal stability, higher crystallinity, and better proton conductivity, making them more suitable for demanding fuel cell conditions, especially under low humidity. The review also discusses important membrane properties such as water uptake, proton transport, and durability challenges. To address performance limitations, the use of composite membranes with suitable reinforcements and functional fillers is explored as a strategy to enhance conductivity, mechanical strength, and long‐term stability. Overall, this review sets the foundation for understanding the significance of SSC‐PFSA membranes and their potential in next‐generation fuel cells.