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制备一种炭纳米纤维-天然石墨复合材料,以改善作为锂离子电池阳极材料的天然石墨的倍率性能。通过优化控制天然石墨上炭纳米纤维的生长量及其形状提高了天然石墨的循环性能和倍率性能。与天然石墨原料相比,炭纳米纤维-天然石墨复合材料第一次放电容量达到了95%。炭纳米纤维的生长量被严格地控制在天然石墨质量的15%以下。研究发现:由于炭纳米纤维对充放电过程中阳极的体积膨胀和收缩程度的控制作用,天然石墨表面边位上生长的类似常青藤形的炭纳米纤维对倍率性能的提高最为有效。提出采用炭纳米纤维-天然石墨复合材料的原理结构模型解释重复充放电过程中电极的体积稳定性。通过在石墨表面上生长类常青藤形炭纳米纤维而使得SEI(固体电解质界面)变薄并减少了充放电过程中阳极的体积变化,因而提高了倍率性能。
A carbon nanofiber-natural graphite composite was prepared to improve the rate capability of natural graphite as an anode material for lithium-ion batteries. By optimizing the control of natural graphite carbon nanofiber growth and its shape to improve the natural graphite cycle performance and rate performance. Compared with natural graphite raw materials, carbon nanofiber - natural graphite composite discharge capacity reached 95% for the first time. The growth of carbon nanofibers is strictly controlled below 15% of the quality of natural graphite. It is found that the carbon nanotube-like carbon nanofibers grown on the edge of natural graphite are most effective for increasing the rate performance due to the control effect of the carbon nanofibers on the volume expansion and contraction of the anode during charging and discharging. The principle structure model of carbon nanofibers-natural graphite composites is proposed to explain the volume stability of electrodes during repeated charge-discharge. The rate capability is improved by thinning the SEI (solid electrolyte interface) and reducing the volume change of the anode during charging and discharging by growing the type of Ivy-like carbon nanofibers on the graphite surface.