Enhanced bipolar membrane for durable ampere-level water electrolysis

Abstract

Bipolar membrane (BPM) electrolyzers maintain a steady-state pH gradient, enabling optimal kinetics for electrode reactions. Traditional BPMs face issues with slow water dissociation (WD) kinetics and water transport limitations at high current densities, causing frequent failures during ampere-level electrolysis. This study introduces a durable BPM through strategic catalytic interface design and advanced membrane layer engineering. We synthesized a novel WD catalyst, 4-tertiary amine calix[4]arene-modified graphene oxide (GO-NCA), and integrated it into the BPM interface to enhance active site exposure and internal electric field strength for faster WD kinetics. The membrane, engineered to a thickness of ~32 µm, prevents interfacial delamination at high current densities. In a flow-cell electrolyzer, it achieved competitive cell voltages of 1.9 V at 1,000 mA cm–2 and 3.9 V at 6,500 mA cm–2. It also sustained over 500 hours of operation at 500 mA cm–2 and 60 °C, demonstrating exceptional durability. These findings set a new benchmark for BPM performance, advancing water electrolysis technology for practical applications.