Vanadium Pentoxide-Based Composite Synthesized Using Microwave Water Plasma for Cathode Material in Rechargeable Magnesium Batteries

Multivalent cation rechargeable batteries are expected to perform well as high-capacity storage devices. Rechargeable magnesium batteries have an advantage in terms of resource utilization and safety. Here, we report on sulfur-doped vanadium pentoxide (S-V₂O₅) as a potential material for the cathodes of such a battery; S-V₂O₅ showed a specific capacity of 300 mAh·g^-1. S-V₂O₅ was prepared by a method using a low-temperature plasma generated by carbon felt and a 2.45 GHz microwave generator. This study investigates the ability of S-V₂O₅ to achieve high capacity when added to metal oxide. The highest recorded capacity (420 mAh·g^-1) was reached with MnO₂ added to composite SMn-V₂O₅, which has a higher proportion of included sulfur than found in S-V₂O₅. Results from transmission electron microscopy, energy-dispersive X-ray spectroscopy, Micro-Raman spectroscopy, and X-ray photoelectron spectroscopy show that the bulk of the SMn-V₂O₅ was the orthorhombic V₂O₅ structure; the surface was a xerogel-like V₂O₅ and a solid solution of MnO₂ and sulfur.