Challenges in membrane electrode assemblies at elevated temperatures for proton exchange membrane fuel cells: A review

Abstract

Elevated temperatures within membrane electrode assemblies (MEAs) have gained considerable attention as the development of proton exchange membrane fuel cells (PEMFCs) has progressed. For PEMFCs to achieve widespread commercialization, ensuring the stable operation of MEA under elevated temperatures is essential, but elevated temperatures create several challenges that can negatively impact a PEMFC’s performance and lifespan. These challenges include limited mass transfer, charge conduction, and electrochemical reactions, as well as difficulty managing water and gas flows within a system. elevated temperatures also induce the accelerated degradation of materials and structures, thereby affecting the long-term durability of various MEA components. This review provides an in-depth analysis of these challenges, describing the causes and classifications of elevated temperature states within a MEA and the critical changes in transport processes and load response characteristics that they cause. It also discusses the effects of elevated temperatures on the material properties and structural integrity of MEA components (catalyst layer, proton exchange membrane, and gas diffusion layer), and the resulting performance loss mechanism. Recent progress in overcoming challenges caused by the elevated temperatures is also summarised. Finally, based on the identified challenges and current research, the review emphasises the significant role of heat in suboptimal MEA performance and lifespan and offers valuable insights into future directions for optimizing MEA performance and longevity under elevated temperatures. This provides guidance for the further development of PEMFCs for applications under elevated temperatures.