Unraveling the Mechanism of Cooperative Redox Chemistry in High-Efficient Zn2+ Storage of Vanadium Oxide Cathode

The inferior capacity and cyclic durability of V2O5 caused by inadequate active sites and sluggish kinetics are the main problems to encumber the widespread industrial applications of vanadium-zinc batteries (VZBs). Herein, a cooperative redox chemistry (CRC) as electron carrier is proposed to facilitate the electron-transfer by capturing/providing electrons for the redox of V2O5. The increased oxygen vacancies in V2O5 provoked in situ by CRC offers numerous Zn2+ storage sites and ion-diffusion paths and reduces the electrostatic interactions between vanadium-based cathode and intercalated Zn2+, which enhance Zn2+ storage capability and structural stability. The feasibility of this strategy is fully verified by some CRCs. Noticeably, VZB with [Fe(CN)(6)](3-)/[Fe(CN)(6)](4-) as CRC displays conspicuous specific capacity (433.3 mAh g(-1)), approximate to 100% coulombic efficiency and superb cyclability (approximate to 3500 cycles without capacity attenuation). Also, the mechanism and selection criteria of CRC are specifically unraveled in this work, which provides insightful perspectives for the development of high-efficiency energy-storage devices.

Automated summary

A cooperative redox chemistry (CRC) strategy is proposed to enhance the capacity and cyclic stability of V2O5. The VZB with [Fe(CN)(6)](3-)/[Fe(CN)(6)](4-) as CRC displays excellent performance.