Layered magnesium vanadate film electrodes as high-performance cathode materials for thin-film non-aqueous zinc-ion batteries

Thin-film non-aqueous zinc -ion batteries (ZIBs) are recognized as an alternative energy storage technology with large-scale application prospects. The use of organic electrolytes with a wide window of electrochemical stability to construct non-aqueous ZIBs results in high operating voltage and energy density. In this paper, magnesium vanadate (Mg 0.01 V 2 O 5 ) films were in situ grown and annealed on indium tin oxide (ITO) conductive glass using low-temperature liquid-phase deposition, and directly assembled into thin-film ZIBs. The battery achieved a stable capacity of 137.5 mA h m - 2 after 80 cycles at 167 mA m - 2 . In addition, it exhibited an initial capacity of 104.1 mA h m - 2 at 250 mA m - 2 and a capacity retention of 75.6 % after 200 cycles. Good rate performance feedback was also obtained. According to X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), the electrochemical reaction process of the Mg 0.01 V 2 O 5 film electrode was analyzed and the insertion/extraction mechanism of Zn 2+ was investigated. Due to the instability of the V 2 O 5 structure, the pre-inserted layer of Mg 2+ plays a role as a pillar between layers during preparation, supporting the vanadium -oxygen layer and improving structural stability and battery life. At the same time, thin-film ZIB directly composed of film, diaphragm, electrolyte and zinc sheet has good diffusion dynamics, simplicity and size controllability, making it more suitable for commercial applications. Therefore, the thin-film non-aqueous ZIBs in this work may provide new ideas for mobile novel micro power sources.