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

The VO 2 after Mn-doped and PVP-modified as aqueous zinc ion battery cathode materials. Both embedding of Mn and the modification of PVP can improve the morphology and internal structure of the material to improve performance. • Mn-doped and PVP-modified VO 2 as cathode materials for aqueous zinc battery. • Surfactant PVP significantly improves the morphology of the material. • The insertion of Mn ions boosts the internal structure and stability. • Dual engineering strategy of intercalation and morphology improvement. 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 VO 2 layered structure, and improves the morphology through polyvinylpyrrolidone (PVP) to increase the specific surface area, thereby obtaining MnVO 2 -PVP. Increasing the number of electrochemically active sites allows it to have faster ion diffusion kinetics and better long-term cycle stability. The synthesized MnVO 2 -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 MnVO 2 -PVP can lay a foundation for the improvement of the synthesis method of ZIBs cathode materials in the future.