Use of galvanostatic charge method as a membrane electrode assembly diagnostic tool in a fuel cell stack

To better measure and monitor the membrane electrode assembly (MEA) status in polymer electrolyte membrane fuel cell (PEMFC) stack, a galvanostatic charge method is improved. The electrochemical active surface area (EAS), double-layer capacitance, hydrogen crossover current, and cell ohmic resistance can be measured by this method. In this method, two or more constant currents are applied to the fuel cell stack, and the voltage response between two electrodes of each cell is recorded and analyzed. Tests on a two-cell stack which is supplied with hydrogen in anode and nitrogen in cathode are carried out, and the influences of temperature and relative humidity (RH) on the MEA parameters are investigated. Results show that with an increase of RH, both double-layer capacitance and EAS increase, while hydrogen crossover current and cell ohmic resistance decrease. With an increase of temperature, hydrogen crossover current increases, cell ohmic resistance decreases, and EAS and double-layer capacitance show little change. The galvanostatic charge method shows a convenient way to research cell consistency and MEA lifetime in a fuel cell stack.