Dipole-unit mediated Co-solute engineering to construct nanodomain electrolytes for highly reversible and shuttle-free ZnI2 batteries

Aqueous zinc ion batteries (ZIBs) are promising energy storage technologies, but face formidable challenges from hydrogen evolution reaction, dendrite growth, and active material shuttle. However, how to manipulate the electrolyte structure at the nanoscale to boost battery performance remains largely unexplored. Herein, nanodomain electrolytes with structural nano-heterogeneity are developed by introducing α-Dipole Unit as co-solute and through their self-assembly, which enables precise control over ion-transport kinetics and interfacial reversibility of both anode and cathode. The ionized α-dipole units self-aggregate to form clusters induced by the dipole effect, which not only reconstructs hydrogen bond network of electrolyte and realizes the rapid diffusion of Zn 2+ to obtain HER/dendrite-free Zn anode, but also serves as barrier to inhibit the shuttle effect of I 3 − via repulsion-capture synergy mechanism. Remarkably, the Zn symmetric cells can still maintain a satisfactory cycle life at a low temperature of −20 °C, and the capacity retention rate of the assembled Zn I 2 battery is as high as 94.31 % after 13,000 cycles. This pioneering attempt to manipulate electrolyte nanostructure reveals a new dimension in electrolyte design for high-performance batteries.