Weaker Interactions in Zn2+ and Organic Ion‐pre‐intercalated Vanadium Oxide toward Highly Reversible Zinc‐ion Batteries

Abstract

Driven by safety issues, environmental concerns, and high costs, rechargeable aqueous zinc‐ion batteries (ZIBs) have received increasing attention in recent years owing to their unique advantages. However, the sluggish kinetics of divalent charge Zn2+ in the cathode materials caused by the strong electrostatic interaction and their unsatisfactory cycle life hinder the development of ZIBs. Herein, organic cations and Zn2+ ions co‐pre‐inserted vanadium oxide ([N(CH3)4]0.77,Zn0.23)V8O20·3.8H2O are reported as the cathode for ultra‐stable aqueous ZIBs, in which the weaker electrostatic interactions between Zn2+ and organic ion‐pinned vanadium oxide can induce the high reversibility of Zn2+ insertion and extraction, thereby improving the cycle life. It is demonstrated that ([N(CH3)4]0.77,Zn0.23)V8O20·3.8H2O cathodes deliver a discharge capacity of 181 mA h g−1 at 8 A g−1 and ultra‐long life span (99.5% capacity retention after 2000 cycles). A reversible Zn2+/H+ ions (de)intercalation storage process and pseudocapacitive charge storage are characterized. The weaker interactions between organic ion and Zn2+ open a novel avenue for the design of highly reversible cathode materials with long‐term cycling stability.