An alkaline electrolyzer having a diaphragm surface coating to enable bubble formation and thus reduce the crossover rates of the product gases

Abstract

Alkaline electrolyzer technology is widely considered the most mature and cost-effective way of producing green hydrogen, provided the electricity to operate the electrolyzer is generated via renewable energies. These electrolyzers typically consist of two electrodes, anode and cathode, separated by a diaphragm which is often Zirfon™, a porous composite separator material composed of a polysulfone matrix and ZrO in powder form. This porous membrane allows for the ion transport in the electrolyte and separates the product gases hydrogen and oxygen from each other. However, there are dissolved product gases in the liquid electrolyte that cross the porous membrane via diffusion. The main reason for this crossover rate is the fact that the aqueous liquid electrolyte phase is supersaturated with hydrogen on one side and oxygen on the other. We are proposing to add a layer of coating to the outside faces of the Zirfon membrane to promote the formation of hydrogen/oxygen bubbles outside of the membrane and thus reduce the hydrogen and oxygen crossover.