Toward Forty Thousand‐Cycle Aqueous Zinc‐Iodine Battery: Simultaneously Inhibiting Polyiodides Shuttle and Stabilizing Zinc Anode through a Suspension Electrolyte

Abstract Aqueous zinc‐iodine (Zn‐I 2 ) batteries are promising candidates for grid‐scale energy storage due to their safety and cost‐effectiveness. However, the shuttle effect of polyiodides, Zn corrosion, and accumulation of by‐products restrict their applications. Herein, a simple vermiculite nanosheets (VS) suspension electrolyte is designed for simultaneous confinement of polyiodides and stabilization of Zn anode. It is found that the generation of I 5 − as dominant intermediate and the precipitation reaction between I 5 − and alkaline by‐products should cause irreversible iodine species loss. Benefiting from the high binding energy between polyiodides and silica‐oxygen bonds of VS, dissolved polyiodides are effectively anchored on the surface of VS suspended in the bulk electrolyte to suppress the shuttle effect, which is confirmed by in situ Raman, Ultraviolet‐visible characterizations and theoretical calculations. Furthermore, the self‐assembly VS interfacial layer on the surface of Zn anode hinders side reactions induced by polyiodides. Meanwhile, the interlayer and surface excess negative charges of VS tend to be compensated by Zn 2+ from diffuse layer, which serves as ion accelerators for transferring Zn 2+ at the interface immediately, rendering dendrite‐free Zn plating/stripping behavior. Consequently, the Zn‐I 2 battery with VS electrolyte achieves an ultra‐long lifespan of 40000 cycles with a negligible capacity decay at 20 C.