Current Challenges and Perspectives of Polymer Electrolyte Membranes

Polymer electrolyte membranes are charged polymers in the membrane shape, which can separate the anode reaction from the cathode reaction, allowing the fabrication of compact and highly efficient electrochemical devices. In recent years, great success has been witnessed in the development of advanced polymer electrolyte membranes, driven by the fast development of fuel cells that promise a clean and highly efficient sustainable energy supply. However, drawbacks limiting the widespread adoption of polymer electrolyte membranes still exist. These include the high cost of fluorinated polymer electrolyte membranes, the poor ion transport capability of non-fluorinated aromatic polymer-based polymer electrolyte membranes (especially under low-humidity conditions), the insufficient durability, and the function-led design of advanced polymer electrolyte membranes for applications beyond fuel cells. Herein we briefly discuss several important challenges that should be solved before polymer electrolyte membranes could be extensively adopted in real-world applications. These challenges include how to break through the limitation of phase-separation polymer electrolyte membrane design strategy on further increasing membrane conductivity, how to develop proton exchange membranes for high-temperature and low-humidity working environments, and how to design an alkaline-resistant anion exchange membrane and target its applications beyond hydrogen fuel cells. We also introduce breakthroughs made in these aspects during the past few years and suggest future directions that require extra attention.