Controlled Hydrothermal Growth and Li⁺ Storage Performance of 1D VO_x Nanobelts with Variable Vanadium Valence

One-dimensional (1D) vanadium oxide nanobelts (VO_x NBs) with variable V valence, which include V₃O₇·H₂O NBs, VO₂ (B) NBs and V₂O₅ NBs, were prepared by a simple hydrothermal treatment under a controllable reductive environment and a following calcination process. Electrochemical measurements showed that all these VO_x NBs can be adopted as promising cathode active materials for lithium ion batteries (LIBs). The Li⁺ storage mechanism, charge transfer property at the solid/electrolyte interface and Li⁺ diffusion characteristics for these as-synthesized 1D VO_x NBs were systematically analyzed and compared with each other. The results indicated that V₂O₅ NBs could deliver a relatively higher specific discharge capacity (213.3 mAh/g after 50 cycles at 100 mA/g) and median discharge voltage (~2.68-2.71 V vs. Li/Li⁺) during their working potential range when compared to other VO_x NBs. This is mainly due to the high V valence state and good crystallinity of V₂O₅ NBs, which are beneficial to the large Li⁺ insertion capacity and long-term cyclic stability. In addition, the as-prepared VO₂ (B) NBs had only one predominant discharge plateau at the working potential window so that it can easily output a stable voltage and power in practical LIB applications. This work can provide useful references for the selection and easy synthesis of nanoscaled 1D vanadium-based cathode materials.