Layered hydrated vanadium oxide as highly reversible intercalation cathode for aqueous Zn-ion batteries

Aqueous Zn-ion batteries(ZIBs)hold great potential in large-scale energy storage systems due to the merits of low-cost and high safety.However,the unstable structure of cathode materials and sluggish(de)intercalation kinetics of Zn2+pose challenges for further development.Herein,highly reversible aqueous ZIBs are constructed with layered hydrated vanadium oxide as a cathode material.The electrochemical performances are further tested with the optimized electrolyte of 3M Zn(CF3SO3)2 and a cut-off voltage of 0.4 to 1.3 V,exhibiting a remarkable capacity of 290mAh g−1 at 0.5Ag−1,and long-term cycling stability at high current density.Furthermore,the Zn2+storage mechanism of V3O7⋅H2O is recognized as a highly reversible(de)intercalation process with good structural stability,implying the potential application in the field of large-scale energy storage.

A functionalized separator enables dendrite-free Zn anode via metal-polydopamine coordination chemistry

Designing a multifunctional separator with abundant ion migration paths is crucial for tuning the ion transport in rocking-chair-type batteries.Herein,a polydopamine-functionalized PVDF(PVDF@PDA)nanofibrous membrane is designed to serve as a separator for aqueous zinc-ion batteries(AZIBs).The functional groups(OH and NH)in PDA facilitate the formation of Zn O and Zn N coordination bonds with Zn ions,homogenizing the Zn-ion flux and thus enabling dendrite-free Zn deposition.Moreover,the PVDF@PDA separator effectively inhibits the shuttling of V-species through the formation of V-O coordination bonds.As a result,the Zn/NH_(4)V_(4)O_(10) battery with the PVDF@PDA separator exhibits enhanced cycling stability(92.3%after 1000 cycles at 5 A g^(-1))and rate capability compared to that using a glass fiber separator.This work provides a new avenue to design functionalized separators for high-performance AZIBs.