Assessing the degradation pattern and mechanism of membranes in polymer electrolyte membrane fuel cells using open-circuit voltage hold and humidity cycle test protocols

As the degradation of polymer electrolyte membranes (PEMs) shows catastrophic failures with pinholes and cracks, studies on PEM degradation are essential to improve the reliability and lifetime of polymer electrolyte membrane fuel cell (PEMFC) membrane electrode assemblies (MEAs). However, the investigation of the degradation patterns and understanding of the degradation mechanisms of PEMs are still very limited at the PEMFC MEA level. Herein, open-circuit voltage (OCV) hold (chemical degradation) and humidity cycle test (mechanical degradation) protocols are applied to assess the durability of membrane components of PEMFC MEAs. OCV hold test is conducted at low relative humidity (30%) and OCV condition for 540 h. Humidity cycle test (5000 cycles) is carried out under repeating low (0%) and high (150%) relative humidities. We investigate degradation patterns and mechanisms of PEMs for MEAs after OCV hold and humidity cycle tests using various electrochemical and physicochemical analyses tools. The present study, by providing fundamental understanding of major degradation mechanisms, generates scientific information regarding design tools for the fabrication of highly durable PEMs. Additionally, this study, through accelerated degradation tests, can provide baseline information regarding the durability and lifetime of PEMs by statistically analyzing the deterioration pattern of MEAs.