Construction of iodine-rich solid electrolyte interphase to achieve highly stable aqueous zinc-ion batteries

Aqueous zinc ion batteries (AZIBs) are considered highly potential secondary energy storage equipment for their higher energy density, lower risk, and affordability. However, parasitic reactions within the anode affect the Zn²⁺ deposition behavior with uncontrollable dendrite formation significantly shortening the battery lifetime. For improvement of the Zn anode cycling stability, tetraethylammonium iodide (TEAI), a multifunctional additive was introduced into ZnSO₄, which constructs an iodine-rich solid electrolyte interphase (SEI) on the zinc anode surface and significantly inhibits the parasitic reactions and nucleation of zinc dendrites. Furthermore, the TEAI also reshapes the solvation sheath of Zn²⁺, contributing to better transportation kinetics of zinc ions. Attributing to these functions, highly stable AZIBs are realized with the addition of TEAI, in which a stable cycling life of over 3500 h was achieved for symmetric Zn//Zn batteries under 1 mA cm^-2. With higher current densities, the battery also exhibited excellent cycling stability over 3500 h. Full cells with the V₂O₅ cathode were fabricated to examine the commercial availability of TEAI additives, achieving a high reversible discharge capacity of 381 mAh g^-1, and the capacity of 102 mAh g^-1 was still maintained after 800 cycles at 1 A g^-1.