Boosting the active sites and kinetics of VO2 by Mn pre-intercalated and PVP modified nanostructure to improve the cycle stability for aqueous zinc batteries

Abstract Aqueous zinc ion batteries (ZIBs) have attracted extensive attention because of its high cost-performance and high safety. This study reports a structural engineering method that embeds Mn ions as pillars into the VO2 layered structure, and improves the morphology through polyvinylpyrrolidone (PVP) to increase the specific surface area, thereby obtaining MnVO2-PVP. Increasing the number of electrochemically active sites allows it to have faster ion diffusion kinetics and better long-term cycle stability. The synthesized MnVO2-PVP with nanoprism and nanosheet composite structure shows a remarkable capacity of 470.2 mAh g-1 at 0.5 A g-1, and also has excellent cycle stability at 5000 times at 10 A g-1. The capacity after cycling is 176.5 mAh g-1, with high energy density (179 W h kg-1) and power density (7000 W kg-1). The synthesis method and marvelous performance of MnVO2-PVP can lay a foundation for the improvement of the synthesis method of ZIBs cathode materials in the future.