Anodic Hydration V₂O₃@C for Mg-Ion Battery Cathode

Magnesium-ion batteries are a promising candidate as a next-generation energy storage systems due to high working voltage, high abundance of magnesium metal, and multivalent nature of magnesium-ion. However, finding a suitable cathode material presents a major challenge: low practical capacity and low power density. Due to the strong interaction of the Mg²⁺ ions with the metal oxides commonly used in the cathode. To solve these issues, we demonstrated a novel Mg ion storage mechanism using the in-situ anodic hydration reaction of V₂O₃@C. Through In-situ XRD and Solid-state NMR, we observed the development of V₂O₃@C as a high-power energy storage material during anodic hydration of crystal, which displayed a capacity of more than 381.0 mA h g^-1 at 0.2 A g^-1 and 130.4 mA h g^-1 at 50.0 A g^-1. This work not only provides a new type of cathode material for the magnesium-ion system, but also suggests a new mechanism to prevent the loss of active cations due to irreversible reaction (i.e. formation of solid electrolyte interface (SEI) layer) that occurs in the cathode material during the first charge and discharge.