High performance of Mn-doped VO2 cathode for aqueous zinc-ion batteries: An insight into Zn2+storage mechanism

VO2 (B), as a potential cathode of aqueous zinc-ion batteries (AZIBs), suffers from its intrinsic inferior electrical conductivity. Herein, Mn-doping VO2 (MnVO) has been designed to modify its electronic structure, and thus improve the Zn2+ storage performance. The obtained MnVO electrode exhibits an excellent electrochemical performance at the current density of 5 A/g, especially after 2000 cycles, giving advanced capacity retention of 80.7 % within 10,000 cycles. Density functional theory (DFT) and experiment data demonstrate this superior electrochemical performance can be attributed to the in-situ generated Mn-doped Zn0.25V2O5 center dot nH2O (ZnVO) which might arise from the changed electron density introduced by Mn-dopant. The as-produced ZnVO possesses a bilayer structure with a large interlayer spacing of 11.55 angstrom facilitating the increase of Zn2+ dynamics and the number of active-site for Zn2+ storage. The results bring a new prospect to design and manufacturing high electrochemical performance vanadium-based cathode for AZIBs.