Bioinspired Spatially Topological Strategy Boosts the Anion Exchange Membrane for Industrial-scale Water Electrolysis

The transport of ions through the anion exchange membrane (AEM) depends on the overall energy barriers imposed by the collective interplay of ion channel architecture. The efficient transport of water and ions can be observed ubiquitously in plants. Inspired by the pectin in nature, we developed a spatially topological strategy for designing high-performance AEMs. To achieve precision control at the molecular level, several spatially topological molecules such as triptycene and 9,9’-spirobifluorene were utilized as single or dual framework centers for the anion exchange membrane. By manipulating the ratio of triptycene and 9,9’-spirobifluorene in the polymer, a high ionic conductivity (197.4 mS cm-1 at 80 °C) and an exceedingly low swelling ratio (8.6% at 80 °C) can be attained. The present AEM-WEs achieved a new record high current density of 8.4 A cm−2 at 2.0 V with a 1 M KOH at 80 °C using platinum group metal (PGM)-free catalysts, which surpassed that of state-of-the-art proton exchange membrane water electrolyzers (PEM-WEs) (~ 6 A cm−2 at 2.0 V) and operated stably at a current density of 2 A cm−2 with a cell voltage of 1.8 V for more than 600 h at 60 °C. Notably, when we used the cell with five stacked PGM-free based membrane (T4-1.0-0.5, 80 μm) electrodes, a hydrogen production rate of 0.54 Nm3 h−1 was achieved. The industrial system demonstrates a high level of efficiency and stability while operating under working conditions with a current density of 1 A cm-2 at 2 V.