Route Analysis and Reduction Method of Parasitic Current in Alkaline Water Electrolyzer

Under the background of global carbon neutrality, water electrolysis hydrogen produced is a widely recognized technology to store the fluctuated and intermittent renewable energy. Alkaline water electrolyzer (AWE) is currently the most popular type of water electrolyzers, with the advantages of technology maturity, cost and lifetime. The parasitic current, taking about 2–10% total energy of AWE, has a great influence on the energy efficiency of AWE. However, its mechanism is not yet clear and reduction method is still under research. In this work, the parasitic current mechanism is firstly analyzed, then its routes are proposed, and at last an estimation method of the domain route of parasitic current is obtained by theoretical derivation with some reasonable assumptions. According to the theoretical analysis, the parasitic current occurs by three routes, namely Route1: electrolysis reaction happens at the electrode surface, and the current flows through the inlet and outlet ducts and manifolds; Route2: reaction occurs on the inner surface of the bipolar plate, and the current flows through the inlet and outlet ducts; Route3: The current flows through the inlet and outlet pipelines and the reaction occurs at the inner surface of pipes. And route 1 is possibly the dominated route of parasitic current. For parasitic current route 1, a theoretical derivation is obtained. Moreover, some feasible methods to reduce parasitic current are proposed.