Comparative performance evaluation of self-humidifying PEMFCs with short-side-chain and long-side-chain membranes under various operating conditions

Highlights: • The performance of self-humidifying PEMFCs is analyzed under various operating conditions. • Two membranes with different side-chain lengths are used as the electrolyte. • The operating conditions are optimized by using response surface methodology. • Self-humidification characteristics are analyzed based on the dynamic response. • The short-side-chain membrane shows better system efficiency and stability. The performance of a proton electrolyte membrane fuel cell (PEMFC) with a perfluorosulfonic-acid-based membrane is strongly dependent on the water content in the membrane. In this study, comparative performance evaluation of self-humidifying PEMFCs with short-side-chain (SSC) and long-side-chain (LSC) membranes is conducted under various operating temperatures, air stoichiometries, back pressures, and voltages. The optimal operating conditions at each voltage are determined by using response surface methodology. The self-humidifying PEMFC with the SSC membrane exhibits higher power density than that with the LSC membrane owing to higher water retention. The dominant operating parameter for the system performance changes from the back pressure to air stoichiometry with a decrease in the voltage. Moreover, based on the dynamic response tests, the self-humidifying PEMFC with the SSC membrane exhibits better reliability and settling time than that with the LSC membrane.