Manipulating defects simultaneously boosts the crystal stability and the electrochemical reversibility toward long-life aqueous zinc ion batteries

A great deal of attention has been paid on vanadium-based materials as the promising cathode candidates for aqueous zinc ion batteries (AZIBs) due to their excellent theoretical capacity. However, the strong interactions among Zn2+, H2O and vanadium-based cathode easily trigger the irreversible dissolution and structure collapse of vanadium, especially at low current density. To address these problems, a defect engineering of sulfur doping (point defect) and heterojunction formation (interface defect) is reported herein for designing a robust S-VO2/V6O13 (SVO) cathode via a one-step sulfurization. The SVO could not only restrict the formation of inactive by-product originating from irreversible dissolution, but also boost the reaction reversibility and kinetics of Zn2+ and H+, simultaneously solving the major questions of capacity degradation. As a result, a series of spectroscopic and theoretical studies verified that SVO-2 obsesses stable crystal structure and manifests excellent Zn2+ and H+ storage performance at both low and high current densities. Specifically, a high capacity retention rate of 85.8% can be achieved with the specific capacity of 416 mAh g-1 after 500 cycles at 0.5 A g-1. Even at 10 A g-1, the specific capacity reaches 252 mAh g-1 after 3000 cycles. This work highlights a practical strategy into designing long-term electrodes with great reliability for aqueous batteries.