锂氟电池用高倍率氟化多壁碳纳米管正极材料

Fluorinated multiwall carbon nanotubes for high rate lithium ion primary batteries

  • 摘要: 研究了相同氟碳比的氟化石墨(F-graphtie)和氟化多壁碳纳米管(F-MWCNTs)的电化学性能。高纯石墨化多壁碳纳米管经氟化处理后,获得一种核壳结构的F-WMCNTs (氟碳原子比C/F=1∶1)。经TEM、XRD、XPS表征表明,F-WMCNTs外层被氟化,形成氟化碳结构,而内层依然保持原有的石墨结构。以此F-WMCNTs作正极活性材料组装成锂氟(Li/CFx)一次电池。经电化学测试表明,在相同的放电倍率下,对比F-graphite电极(C/F=1∶1),F-WMCNTs电极能够有效提高Li/CFx一次电池的放电容量和电压平台。大倍率(≥1 C)放电时,尤其明显。当放电倍率为0.05 C时,F-WMCNTs极和F-graphite电极比容量分别为822 mAh/g和786.1 mAh/g,F-WMCNTs电极放电容量比F-graphite电极提高4.5%。当放电倍率为2 C时,F-WMCNTs电极和F-graphite电极分别达到375.4 mAh/g和283.7 mAh/g,F-WMCNTs电极的放电比容量比F-graphite电极提高了32.2%。F-WMCNTs电极显示出优异的倍率性能。

     

    Abstract: Fluorinated graphite (F-graphite) and multiwall carbon nanotubes (F-MWCNTs) were synthesized by direct fluorination with fluorine gas and used as the cathode materials of lithium primary batteries. Their microstructures were characterized by SEM, TEM, XRD and XPS. Results show that the F-MWCNTs have a core-shell structure with the outer layers fluorinated while the inner ones retain their pristine graphitized structure. A F-MWCNT electrode exhibited a higher discharge capacity and a higher discharge plateau than a F-graphite electrode at the same C rates. The discharge capacities of the F-MWCNT and F-graphite electrodes reached 822 and 786.1 mAh/g at 0.05 C, respectively. The corresponding values reached 375.4 and 283.7 mAh/g at 2 C, indicating an excellent rate performance for the former.

     

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