High-rate performance magnesium batteries achieved by direct growth of honeycomb-like V2O5 electrodes with rich oxygen vacancies

Rechargeable magnesium batteries (RMBs) have emerged as a promising next-generation electrochemical energy storage technology due to their superiority of low price and high safety. However, the practical applications of RMBs are severely limited by immature electrode materials. Especially, the high-rate cathode materials are highly desired. Herein, we propose a dual-functional design of V2O5 electrode with rational honeycomb-like structure and rich oxygen vacancies to enhance the kinetics synergistically. The result demonstrates that oxygen vacancies can not only boost the intrinsic electronic conductivity of V2O5, but also enhance the Mg2+ diffusion kinetics inside the cathode, leading to the good high-rate performance. Moreover, ex-situ X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) characterizations reveal that Mg2+ is mainly intercalated from the (101) plane of V2O5−x based on the insertion-type electrochemical mechanism; meanwhile, the highly reversible structure evolution during Mg2+ insertion/extraction is also verified. This work proposes that the dual-functional design of electrode has a great influence in enhancing the electrochemical performance of cathode materials for RMBs.