High capacity VO2(B) nanostrips synthesized by microwave-hydrothermal method

Abstract

VO2(B) nanostrips were synthesized by microwave-hydrothermal method. The XRD patterns show that VO2(B) nanostrips are pure metastable monoclinic phase. VO2(B) nanostrips, in length of 1.5–2[Formula: see text][Formula: see text]m, width of 200–400[Formula: see text]nm, and thickness of 10–20[Formula: see text]nm, present exposed (001) facets and parallel alignment structure. The VO2(B) nanostrips are composed of nanosheets with 2–5[Formula: see text]nm thickness. A very high initial discharge capacity of 318.3[Formula: see text]mAh[Formula: see text]g[Formula: see text] is obtained and the capacity of 100th cycle is 248.5[Formula: see text]mAh[Formula: see text]g[Formula: see text] (about 78.0% retention) at 50[Formula: see text]mA[Formula: see text]g[Formula: see text]. The capacity fades at about 4.08% per cycle for the first 10 cycles. After 10 cycles, the fading slows down to 0.32% per cycle. The rate performance shows the first discharge capacities of VO2(B) nanostrips are 249.6, 212.0, 181.8, 161.7, and 145.2[Formula: see text]mAh[Formula: see text]g[Formula: see text] at 0.1, 0.2, 0.4, 0.8, and 1.6[Formula: see text]A[Formula: see text]g[Formula: see text], respectively, with around 100% coulombic efficiency. Glycerol and microwave-hydrothermal method contribute to the shaping and thickness of VO2(B) nanostrips with the parallel alignment nanostructure, which directly improves the electrical properties of this material.