EDTA regulates magnesium storage capacity of a layered vanadium oxide cathode

Aqueous magnesium ion batteries (AMIBs) have attracted widespread attention due to their high safety and low cost. However, conventional V₂O₅ material suffers from issues such as narrow interlayer distance, slow Mg²⁺ diffusion kinetics, and severe interfacial side reactions during Mg²⁺ insertion and extraction, resulting in insufficient capacity and cycling performance. This work presents a dual-function organic molecule doping strategy, in which ethylenediaminetetraacetic acid (EDTA) molecules are doped into a layered V₂O₅ to construct an EDTA-V₂O₅ (EVO) composite material. EDTA doping increases the interlayer distance and lowers the Mg²⁺ diffusion energy barrier. More importantly, it changes the surface properties of the material, indirectly regulates the inner Helmholtz plane (IHP) and reconstructs the electric double layer (EDL) structure at the electrode/electrolyte interface. Through theoretical calculations and characterizations, it is revealed that EDTA doping enhances the interfacial stability of V₂O₅ and suppresses the hydrogen evolution side reaction. This synergistic strategy between the body-doping and interface regulation enables 1-EVO (1-EDTA-V₂O₅) to maintain a capacity retention rate of 87.7 % after 2000 cycles at a current density of 1 A g^-1, providing new insights for the development of highly diffusion kinetics, long-life AMIBs cathode.