Challenges and innovations of bipolar membranes to enhance water electrolysis performance

Bipolar membranes (BPMs), a specialized category of ion-exchange membranes, consist of a cation-exchange layer (CEL) and an anion-exchange layer (AEL) seamlessly integrated at their interface. These membranes enable the simultaneous transport of cations (e.g., H⁺) and anions (e.g., OH^-), thereby facilitating hydrogen generation in acidic environments and oxygen evolution under alkaline conditions. Due to their unique characteristics, BPMs exhibit remarkable potential for application in water electrolysis (WE), attracting increasing attention in recent research endeavors. Based on recent experimental findings, several innovative strategies have been proposed to enhance the performance of bipolar membrane water electrolysis (BPMWE) systems. These strategies encompass optimizing polymer chemistry for both the AEL and CEL, engineering asymmetric membrane architectures, integrating catalysts for water dissociation, designing advanced 3D structures at the bipolar interface, and employing cutting-edge fabrication methods. This review offers critical insights and perspectives that are anticipated to propel the advancement of BPM technology in the field of water electrolysis.