Evaluation of double layer capacitance and carbon support corrosion under variable conditions

The performance and longevity of proton-exchange membrane fuel cell (PEMFC) depends on, among, other factors, health, and durability of the catalyst layer. The state of health and degradation rate of PEMFC membrane electrode assemblies (MEAs) is typically assessed using diagnostic markers such as electrochemical surface area (ECSA), gas crossover and double layer capacitance. Recently, galvanostatic charge and discharge techniques have been developed and successfully replicated for both single cell and a fuel cell stack. These methods utilize potential-time differentials and galvanostatic current to calculate ECSA and double layer capacitance (Cdl) and other parameters. However, analyses of double layer capacitances using this method under varying conditions — such as relative humidities, carbon support type — remain limited. Additionally, Cdl as a time-resolved diagnostic marker has not been widely used for stacks when derived from the galvanostatic methods. Here is presented a framework to deconvolute Cdl contributions from Pt, carbon, and ionomer using galvanostatic method, establish degradation patterns and propose a predictive model for remaining useful life.