Synergistic effect of V₃O₇/VO₂ film electrodes as high-performance cathode materials for magnesium-ion batteries

Magnesium -ion batteries have become important candidates for secondary batteries due to their low cost, dendrite-free and multivalent nature. However, the lack of structural stability of most electrode materials and the slow diffusion kinetics of Mg2+ have hindered the development of magnesium -ion batteries. In this work, V3O7/ VO2 film electrodes were grown in situ on indium tin oxide conductive glass using a low-temperature liquid phase deposition method. After calcination at different temperatures in a nitrogen atmosphere, it was concluded that the films calcined at 400 C-degrees had an appropriate crystallinity and biphasic structure. With 0.5 M Mg(ClO4)(2)/ PC as the electrolyte, the initial discharge capacity was 111.5 mA h m(- 2) at 100 mA m(- 2 )and the stabilized capacity was 156.7 mA h m(- 2) after 100 cycles. According to high-resolution transmission electron microscopy, ex-situ X-ray diffraction, and X-ray photoelectron spectroscopy, V3O7, formed by the partial phase transformation of VO2, has an extraordinarily large interlayer space as the calcination temperature increases. It assisted VO2 to increase the Mg2+ transport channels and provided more active sites to promote diffusion kinetics (the average D(Mg)( 2+)was 2.83 x 10(-12) cm(2) s(- 1)). These results may provide a new idea for the use of V3O7/VO2 films as electrode materials for magnesium -ion batteries.