Improved methods to measure hydrogen crossover current in proton exchange membrane fuel cell.

Hydrogen crossover current has a great influence on the performance and durability of proton exchange membrane (PEM) fuel cells. The common measuring method is linear sweep voltammetry (LSV). But some usual approximations, such as ignoring the influence of scan rates or short-circuit resistances, can lead to greater measurement deviations. Therefore, in this study to accurately measure hydrogen crossover current, LSV is improved by building a novel charging model based on fitted zero scan rate curves and on taking effects of short circuit into consideration. On the basis of this new model, galvanostatic charging method is improved by taking short circuit of PEMs into consideration and a mass spectrometry assisted with hydrogen pump is proposed with no need of calibration with standard gas. Hydrogen crossover current and short-circuit resistance of a 34 cm 2 single cell are measured by three improved methods, which are then compared with methods previously available. It is found that hydrogen crossover currents are reduced and more accurate than those obtained by previous methods, and values obtained by different improved methods are highly consistent with each other. So the proposed charging model is valid and can be used to optimize other electrochemical measurements of fuel cells. [ABSTRACT FROM AUTHOR]