Performing cyclic voltammetry in a proton exchange membrane fuel cell stack: what you should keep in mind

Abstract Cyclic voltammetry (CV) is a very commonly used technique for the study of electrochemical interfaces. Its application to proton exchange membrane fuel cell (PEMFC) is of great interest as it is sensitive to change in the catalyst layer and membrane state-of-life. Using cyclic voltammograms, it is possible to easily obtain information on the catalyst roughness factor and the hydrogen cross-over current. This study focuses on the best way to perform CV on individual cells at the stack level. To prevent the whole stack polarisation, eight different connection configurations have been tested to obtain comparable CV as the reference case with current applied on the whole stack. The comparison between the cyclic voltammograms and potentiostatic electrochemical impedance spectroscopy (PEIS) for all these configurations lead to some recommendations for bipolar plates design. Contact resistances and proximity of current and potential connections are the main hindrances to the measurement of reliable CV. The authors advise to maximise as much as possible the number of connection pins and to place them on both sides of the PEMFC bipolar plates. If it is not possible on current design, the authors recommend the use of dynamic ohmic drop compensation to minimise the error regarding the determination of roughness factor. Graphical abstract