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| To measure and monitor the membrane electrode assembly (MEA) status, the cyclic voltammetry (CV) and galvanostatic method are improved and compared. The electrochemical active surface area (EAS), double layer capacitance, H2 crossover current are measured by both the CV and galvanostatic method, and the cell resistance is also gained by the galvanostatic method. In the galvanostatic method, two or more constant currents are applied to a fuel cell stack, and the voltage responds between two electrodes of every cell are recorded and analyzed. Tests on a two-cell stack supplied with hydrogen in the anode and nitrogen in the cathode are carried out, and the influences of the temperature and relative humidity (RH) on the MEA parameters are investigated. Results show that with an increase in RH, both the double layer capacitance and EAS linear increase, while the hydrogen crossover current and cell resistance linear decrease; and with an increase in temperature, the hydrogen crossover current linear increases, cell resistance decreases, EAS and double layer capacitance show little change. The galvanostatic method shows a convenient technique to research the cell uniformity and the MEA lifetime in fuel cell stack. |
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| Keywords:PEM fuel cell; electrochemical active surface area; double layer capacitance; hydrogen crossover current; cell resistance |
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