What We Can Learn from Watermelon Skin for the Design of Artificial Ion-Transport Membranes

Selective ion-transport membranes (ITMs) are core components of electrochemical energy conversion and storage devices. However, the development of low-ion-resistance and high-ion-selectivity transport membranes still poses challenges. To propose effective design strategies for achieving high performance ITMs, this work conducted a deep exploration of watermelon skin membranes (WSMs) obtained by the freezing-exfoliation method through a combination of experimental research and molecular dynamics simulation. The micropores and continuous hydrogen-bonding network constructed by the synergistic effect of cellulose fiber and pectin enables WSM to have an ion conductivity of 235.2 mS cm-1 (RT). The negatively charged groups and many hydroxyl groups modified on the surface of the microporous channels enhance the formate penetration resistance of WSMs by 12.8 times compared to that of commercial Fumasep membranes. Therefore, the Confinement of proton donor and negatively charged group-enriched microporous polymers within three-dimensional framework systems is expected to become a new design strategy for high-performance ITMs.