Preparation of tungsten oxide/carbon macrofilms composite anode electrode and lithium storage performance

Thanks to its high theoretical specific capacity (693 mAh/g), tungsten oxide (WO₃) is a good substitute for anode material of lithium-ion batteries. However, WO₃ suffers a large volume change during the process of lithium-ion removal/embedding, leading to the rapid decline of discharge specific capacity. Therefore, the cycle stability of WO₃ anode electrode has been one of the research focuses. H-WO₃/CMF and S-WO₃/CMF composite electrodes were successfully synthesized on CMF substrate by hydrothermal method and spraying method, respectively. XRD results show that WO₃ in H-WO₃/CMF and S-WO₃/CMF are categorized into monoclinic phase and hexagonal phase respectively. H-WO₃/CMF and S-WO₃/CMF were separately assembled into button cells for electrochemical performance test. The results show that the first discharge specific capacity of H-WO₃/CMF was higher than that of S-WO₃/CMF. When H-WO₃/CMF was cycled at a rate of 0.2 C, the specific discharge capacity reached 635 mAh/g in the first cycle and 510 mAh/g in the 50 cycles, which still showed an upward trend. When S-WO₃/CMF is cycled at 0.2 C, the specific discharge capacity in the first cycle is only 515 mAh/g, and the capacity decays rapidly in the subsequent cycle. Ac impedance test results show that the conductivity of H-WO₃/CMF is higher than that of S-WO₃/CMF. The research results show that H-WO₃/CMF, as the negative electrode of lithium-ion battery, is expected to improve the electrochemical stability of WO₃.