Oxygen defects engineering and structural strengthening of hydrated vanadium oxide cathode by coating glucose hydrothermal carbon and pre-embedding Mn (II) ion for high-capacity aqueous zinc ion batteries.

Vanadium oxide-based cathode with unique layered structure is considered as a candidate for aqueous zinc ion batteries (AZIBs). Unfortunately, considering poor electronic conductivity, sluggish diffusion kinetics, and the destruction of layered structures in the cycling process, the actual capacity and rate capability are constrained. Herein, the glucose hydrothermal carbon (GHC) and transition metal Mn ion have been utilized to incorporate hydrated vanadium oxide (Mn-VOH@GHC). The oxygen vacancies defects of VOH, induced by GHC anchored on surface and Mn inserted between interlayers, provides more active sites, higher electronic conductivity, and faster ion diffusion. In addition, GHC reinforces the integrity of external structure, while Mn ion acts as structural pillars to support the interlayer structure. The Mn-VOH@GHC electrode can produce a high capacity of 530 mAh/g at the current density of 0.2 A/g thanks to these crucial properties, and after 2000 cycles at a high current density of 2 A/g, it can also produce a reversible capacity of 344 mAh/g. The results suggest that the synergistic effect of defect engineering and metal ion pre-insertion provides a new idea in enhancement of the electrochemical performance of AZIBs cathode materials.