Synthesis and Electrochemical Properties of Aluminum-Doped Vanadium Oxide as a Cathode Material for Rechargeable Magnesium Batteries

Rechargeable magnesium batteries (RMBs) have attracted attention as next-generation energy storage systems due to their high safety, large volumetric capacity, low redox potential of magnesium anode, and cost effectiveness. However, the development of highly reversible cathode materials for RMBs with fast intercalation kinetics is very challenging due to the slow diffusion of Mg²⁺ ions and the low reversible capacity, characteristic of divalent magnesium ions in the cathode material. This is a consequence of the strong electrostatic interaction between the Mg²⁺ ions and the cathode material, which makes the reversible intercalation difficult. In this work, a cathode material based on aluminum-doped vanadium oxide with an expanded interlayer space was synthesized. The structure of the material was studied by high-resolution X-ray diffraction. Its electrochemical properties in propylene carbonate magnesium-containing electrolytes have been studied by cyclic voltammetry. The initial values of the specific capacity of the Al_xV₂O₅ cathode of about 136 mAh g^–1 at a scan rate of 0.4 mV s^–1 were obtained from the CVs by integrating the current under the cathodic curve. The analysis of chemical composition of the Al_xV₂O₅ cathode after the discharge cycle showed a significant amount of intercalated magnesium ions.