Preventing Electrode Degradation Against Reverse Current By Interrupting Ion Transfer during Shut-Down in Alkaline Water Electrolysis

The renewable energy integrated alkaline water electrolysis (AWE) is a potential candidate for large scale and economically viable technology for green hydrogen production. However, the periodic power off mode causes reverse current in alkaline electrolyzer, which is inevitable intermittent characteristics of renewable energy sources. The reverse current spontaneously occurs by potential difference between electrodes to release the accumulated charges of electrodes during shut-down state. It adversely affects to the performance and the lifetime of the AWE stacks by an irreversible phase change of the electrodes. To prevent degradation of electrodes against the reverse current, we designed a system interrupting ion transfer by significantly lowering ion conductivity of the electrolyte during power shut-down in the AWE stacks. Consequently, we verify the relationship between the ionic conductivity and reverse current by analyzing the decrease rates of each cell potential corresponding phase change in the AWE stacks during the shut-down state. Through this research, we anticipate providing fundamental solutions to prevent electrode degradation and enhance the durability of stacks for renewable energy integrated AWE system.