Molecule Chemistry Inducing Crystallographic Reorientation and Smart Interface to Boost Zinc-Iodine Battery Capacity

Abstract

Aqueous zinc-iodine batteries (AZIBs) with high theoretical capacities, intrinsic safety, and low cost have been extensively explored as one of next-generation energy storage devices. Nevertheless, in the presence of aqueous electrolytes, AZIBs suffer severe metal corrosion, dendrite growth, and polyiodide shuttling, leading to fast capacity degradation. Here, we report a molecule chemistry strategy by making use of tris(2-cyanoethyl) borate to form a gradient solid electrolyte interface, which dynamically adapts to volume changes and induces even Zn deposits with crystal preferred orientation from (101) to (002) plane, promoting high reversibility and stability of Zn anode. Meanwhile, the molecules adsorbed on the cathode/electrolyte interface can immobilize polyiodide species by the strong interactions and improve conversion kinetics. Benefiting from these advantages, zinc anode exhibits long-term cycling with super-high zinc utilization and superior rate capability at 40 mA cm-2, Zn//I2 full cells also achieve ultralong lifespan (>6000 cycles) at large currents and high mass loading. Remarkably, this strategy also enables the normal operation of Cu//I2 battery with an energy density of 158 Wh kg-1, thus promoting the practical application of aqueous zinc batteries.