Realizing high-performance Zn-ion batteries by a reduced graphene oxide block layer at room and low temperatures

Abstract

Rechargeable aqueous Zn-ion batteries (ZIBs) have attracted great attention due to their cost-effectiveness, high safety, and environmental friendliness. However, some issues associated with poor structural instability of cathode materials and fast self-discharge hinder the further development of ZIBs. Herein, a new configuration is introduced by placing a reduced graphene oxide film as a block layer between the separator and the V2O5·nH2O cathode. This layer prevents the free diffusion of dissolved active materials to the anode and facilitates the transport of Zn ion and electrons, largely improving the cyclic stability and alleviating the self-discharge. Accordingly, the optimized battery delivers a remarkable capacity of 191 mAh g−1 after 500 cycles at 2 A g−1. Moreover, a high capacity of 106 mAh g−1 is achieved after 100 cycles at −20 °C. The strategy proposed is expected to be applicable to other electrode systems, thus offering a new approach to circumvent the critical challenges facing aqueous batteries.