In‐Situ Lattice Tunnel Intercalation of Vanadium Pentoxide for Improving Long‐Term Performance of Rechargeable Magnesium Batteries

Abstract Layered V₂O₅ is a promising and versatile cathode for rechargeable magnesium batteries (RMBs), but its narrow interlayer spacing makes rapid Mg²⁺ diffusion difficult, resulting in poor electrochemical performance. Herein, a facile and scalable technique is established for tailoring the (001) spacing of V₂O₅ by in‐situ polyaniline polymerization. The intercalated polyaniline molecules operate as pillars in the V₂O₅ interlayer, providing plentiful storage sites as well as improved cation diffusivities of Mg ion. As expected, by using V₂O₅/polyaniline as the cathode (anode: Mg metal), a high specific capacity of 361 mAh g⁻¹ with charging/discharging current density of 20 mA g⁻¹ can be achieved for RMBs. Besides, V₂O₅/polyaniline electrode shows favorable rate capability with 103 mAh g⁻¹ at 500 mA g⁻¹ (500 cycles) and ultra long‐term cycling performance after 5000 cycles. Ex situ X‐ray photoelectron spectroscopy is used to study the magnesium storage mechanism of the V₂O₅/polyaniline electrode.