氧化钨/碳纳米管膜复合负极的制备及其储锂性能

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

  • 摘要: 氧化钨(WO3)因具有较高的理论比容量(693 mAh/g)已成为锂离子电池负极材料的有力候选者。但在电池充放电即锂离子脱/嵌入过程中WO3会产生较大的体积变化,导致其放电比容量快速衰减,故对其循环稳定性研究仍是热点之一。文中采用水热法和喷涂法分别在碳纳米管膜(CMF)基底上成功合成了水热型-氧化钨/碳纳米管膜(H-WO3/CMF)和喷涂型-氧化钨/碳纳米管膜(S-WO3/CMF)复合电极。XRD测试结果显示H-WO3/CMF和S-WO3/CMF中的WO3分别属于单斜相和六方相。将H-WO3/CMF和S-WO3/CMF分别组装成扣式电池进行电化学性能测试,结果表明H-WO3/CMF的首次放电比容量高于S-WO3/CMF。当H-WO3/CMF以0.2 C倍率循环时,第1圈放电比容量达到635 mAh/g,循环50圈时放电比容量为510 mAh/g,仍有上升趋势; S-WO3/CMF在0.2 C倍率下循环时,第1圈放电比容量仅为515 mAh/g,在后续循环过程中容量衰减较快。交流阻抗测试结果显示H-WO3/CMF的导电性高于S-WO3/CMF。研究结果表明:H-WO3/CMF作为锂离子电池负极,有望提升WO3的电化学稳定性。

     

    Abstract: 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.

     

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