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

Abstract Layered V 2 O 5 is a promising and versatile cathode for rechargeable magnesium batteries (RMBs), but its narrow interlayer spacing makes rapid Mg 2+ diffusion difficult, resulting in poor electrochemical performance. Herein, a facile and scalable technique is established for tailoring the (001) spacing of V 2 O 5 by in‐situ polyaniline polymerization. The intercalated polyaniline molecules operate as pillars in the V 2 O 5 interlayer, providing plentiful storage sites as well as improved cation diffusivities of Mg ion. As expected, by using V 2 O 5 /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, V 2 O 5 /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 V 2 O 5 /polyaniline electrode.