Enhanced Lithium Storage Performance of VO with Oxygen Vacancy

Orthorhombic phase VO nanosheets with a high V content (V-VO) have been fabricated a facile sol-gel method and freeze-drying technology followed with a vacuum annealing process. XPS tests demonstrated that the content of V in the as-prepared V-VO sample was 7.4%, much higher than that (4.7%) in the VO sample annealed in air. Compared with the VO annealed in air, the V-VO sample exhibited better cycling stability, higher lithium storage activity, and smaller electrochemical reaction resistance when evaluated as a cathode active material for lithium ion batteries. For example, the specific capacity of the V-VO and VO electrodes after 100 cycles at 200 mA g are 224.7 and 199.2 mA h g, respectively; after 200 cycles at 3 A g are 150 and 136.7 mA h g, respectively.