Tailoring microstructure of polysulfone composite membranes for alkaline water electrolysis

Alkaline water electrolysis (AWE) systems have been the focus of increasing attention in the green energy field due to their zero carbon emissions. The composite membrane, as a critical component of AWE, is typically used to enhance hydrogen production efficiency by incorporating nanofillers. However, over time, the separation of nanofillers can result in gas cross-permeation, thereby increasing operational risks. This study introduces polyethyleneimine (PEI) into the composite membrane, where hydrogen bonds are formed within the membrane, resulting in a composite membrane with a tunable microporous structure. The resulting composite membrane separator exhibited outstanding performance, achieving a maximum bubble point pressure of 3.96 bar and a decreased area resistance of 0.21 Ω cm². When subjected to a voltage of 2 V, the composite membrane separator achieved a current density of 896 mA cm⁻² at 80 °C in 30 wt% KOH, demonstrating excellent stability. Compared with existing advanced composite membranes, this membrane exhibited a notable advantage in terms of electrolytic performance. This study offers crucial insights for advancing the development of high-performance AWE membranes.