Characterisation tools development for PEM electrolysers

Electrochemical impedance spectroscopy (EIS), current interrupt (CI) and current mapping (CM) were investigated as in-situ characterisation tools for PEM electrolysers. A 25 cm2 cell with titanium anode and carbon cathode plates were utilised in this study. A commercial MEA consisting of 1 mg IrO2/cm2 on the anode and 0.3 mg Pt/cm2 on the cathode was used. The electrocatalyst was deposited on Nafion® membranes. The electrochemical losses in a PEM electrolyser namely: activation, ohmic and mass transfer losses were identified using EIS and CI and both the advantages and disadvantages of the methods were discussed. The current distribution over the membrane electrode assembly (MEA) at different current densities was measured using the current mapping method. It is also shown that under the given experimental conditions the current density decreases along the serpentine flow field.