Mechanical failure and mitigation strategies for the membrane in a proton exchange membrane fuel cell

Abstract

Proton exchange membrane (PEM) fuel cells are promising zero-emission power source for automobiles, portable devices, backup power system and stationary applications. However, their relatively short lifespan remains a major obstacle to the commercial deployment of this type of fuel cell. The membrane's mechanical degradation is the main cause of early-stage failure in fuel cell lifetimes. In order to provide engineers and researchers with a basis for extending fuel cell durability, this paper presents an overview of important issues relating to mechanical failure and mitigation strategies for PEM fuel cell membranes, drawing on a survey of the existing literature. This review begins with a sketch of failure mechanisms in an effort to establish an unambiguous definition of membrane degradation in each stage of its lifespan. The material properties of typical membranes are outlined below to illustrate the fundamentals of their mechanical behavior and cell degradation. Following the lifespan of a membrane, the causes and mechanisms of mechanical degradation in the fabrication process, cell assembly process, short-term phase and long-term phase of cell operation are discussed in detail. Practical strategies for reducing the degradation rate are introduced to each process. Finally, in-situ and ex-situ methods for the evaluation and characterization of mechanical durability are summarized to pursue the measurement methods and protocols of membranes. The aim is to assess which mechanisms affect the mechanical failure of membranes and how degradation should be mitigated across the entire lifetime of fuel cells. A summary of further work in this area is also provided to give a direction to future research.