Two-Dimensional VO2 Nanosheets with a Controllable Crystalline-Preferred Orientation for High-Performance Zinc-Ion Batteries

Due to the environmental friendliness, cost-effectiveness and inherent safety, rechargeable aqueous zinc ion batteries have attracted much interest as a promising energy storage device. VO2 is one of the most common materials for rechargeable zinc ion batteries. The insertion/extraction of zinc ions within VO2 is highly anisotropic, with different channel sizes along different axes. Therefore, it is quite important to control the orientation of VO2 crystals so as to manipulate the transportation of Zn2+ ions more effectively and sufficiently. Herein, a novel intercalation-type two-dimensional VO2 nanosheet with preferred orientation (PO-VO2) of the c-axis was prepared. Benefitting from the structural merits, the PO-VO2 nanosheets demonstrate an attractive capacity of 511.6 mAh g−1 at a current density of 0.05 A g−1 in a voltage of 0.2–1.6 V, which is obviously better than that of many vanadium oxide-based cathodes reported until now. The PO-VO2//Zn aqueous zinc ion full cell exhibits a high energy density of 290.5 Wh kg−1 at a power density of 38.4 W kg−1 (based on the mass of the VO2 cathode electrode). The outstanding energy storage behavior, together with the facile and affordable synthesis route, endows the PO-VO2 nanosheets with promising applications for aqueous zinc ion batteries.