Automatic operation of decoupled water electrolysis based on bipolar electrode

Abstract

Electrolytic hydrogen production faces a technological issue of gas crossover through the ion-membrane between hydrogen and oxygen chambers, especially under renewable energy low power driving conditions. As a solution, decoupled water electrolysis was proposed and has made important progress in laboratory research but faces the problem of how to implement it in industry. The present work develops a decoupled alkaline water electrolysis system without the need to change the filter press structure of industrial electrolyzers. A wireless bipolar electrode was designed and prepared from a redox pair (NiOOH/Ni(OH)2), which functions as a substitute for conventional ion-membrane but enables complete blocking of the gas crossover (and ion transfer also) between the hydrogen and oxygen chambers. A matching control scheme was designed and implemented for continuous water electrolysis. The high purity hydrogen production achieved a coulombic efficiency of 99.2% and a specific electricity consumption of 57.5 kWh kg−1 H2 at a current density of 50 mA cm−2. This bipolar decoupling scheme of automatic operation makes an important step towards industrial implementation of decoupled water electrolysis technology.