Unlocking the potential of spinel MnV2O4 for highly durable aqueous zinc-ion batteries

Abstract

Aqueous zinc-ion batteries (AZIBs) have received comprehensive attention as promising candidates for large-scale energy storage owing to high security, low cost, and environmental friendliness. Developing appropriate cathode materials is of great significance for high-efficiency Zn2+ storage. Herein, we proposed an efficient in-situ electrochemical pretreatment strategy to unlock the potential of non-electrochemically active spinel MnV2O4via an irreversible phase reconstruction from crystalline structure to short-range ordered amorphous state. Specifically, the reconstructed electrodes not only deliver abundant active sites for Zn2+ ions accommodation, but also shorten diffusion paths for rapid reaction kinetics, thus achieving superior electrochemical properties. As revealed, the optimized electrodes present a prominent specific capacity of 445 mA h g−1 at 0.1 A g−1, a high capacity retention of 73.1 % over 2000 cycles at 5 A g−1, as well as exceptional energy density of 335 W h kg−1 and power density of 176 W kg−1 based on the mass of cathode. In addition, the reaction mechanism during Zn2+ ions storage process is systematically investigated by ex-situ X-ray diffraction and X-ray photoelectron spectroscopy. This in-situ electrochemical conversion mechanism sheds light on a new methodology of designing desirable cathode materials for aqueous ion batteries.