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

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),Zn-0.23)V8O20 center dot 3.8H(2)O 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),Zn-0.23)V8O20 center dot 3.8H(2)O 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.