螺旋纳米碳纤维在锂离子电池负极中的应用研究

发布时间：2018-03-21 01:18

  本文选题：螺旋纳米碳纤维　切入点：化学气相沉积法　出处：《四川理工学院》2015年硕士论文　论文类型：学位论文

【摘要】：锂离子电池具有开路电压高,比容量大,安全环保,使用寿命长等诸多优点,已在各领域广泛使用,但动力型和大功率设备的大量应用对锂离子电池提出了更高要求,传统的碳材料已不能满足高性能的锂离子电池要求,只有探索新的储能材料才能突破锂离子电池的发展瓶颈。螺旋纳米碳纤维的导电性能好,比表面积大,石墨片层结构无序度高,能提供更多锂离子嵌入与脱出的通道,有利于提高锂离子电池的充放电容量、循环稳定性以及倍率性能。本文主要研究螺旋纳米碳纤维的制备、微观结构与电化学性能。(1)以三水合酒石酸铜为催化剂前驱体、乙炔为碳源,采用化学气相沉积法制备螺旋纳米碳纤维。在250-380℃制备的螺旋纳米碳纤维,螺旋不规则,直径在100-300nm;在480-680℃制备的螺旋纳米碳纤维,螺旋规则,形貌均匀,直径约为100nm左右。在480℃的低温条件下制备出螺旋规则、形貌均匀的螺旋纳米碳纤维,实验流程简单,操作方便,实验重现性好,能耗和成本低,可推广到工业化。(2)480℃、580℃、680℃制备的螺旋纳米碳纤维作为锂电池负极材料,首次放电比容量分别为811m Ah/g、702m Ah/g、613m Ah/g,循环充放电40次后,放电比容量分别为503m Ah/g、443m Ah/g、439m Ah/g,库伦效率分别为97.8%、98.6%、97%,表现出良好的循环性能和高倍率性能。在一定温度范围,随着制备温度的升高,螺旋纳米碳纤维的石墨片层有序度提高,可逆嵌锂容量降低。(3)DNA状、弹簧状、麻花状的螺旋纳米碳纤维作为锂电池负极材料,首次放电比容量分别是1066m Ah/g、834m Ah/g、702m Ah/g,循环充放电40次后,放电比容量分别为584m Ah/g、501m Ah/g、443m Ah/g,库伦效率分别为98.5%、99%、98.6%。DNA状的螺旋纳米碳纤维的充放电比容量最高,弹簧状的次之,麻花状的最低。DNA状的螺旋纳米碳纤维表面粗糙,碳沉积不规则,为维持其DNA结构的螺旋,出现许多“搭接孔”或“微裂纹”,锂离子可嵌入到碳纳米纤维的石墨微晶的表面及边缘,为锂离子的脱出和嵌入提供更多的通道,更利于充放电。
[Abstract]:Li-ion batteries have many advantages such as high open-circuit voltage, large specific capacity, safety and environmental protection, long service life and so on, and have been widely used in various fields. However, a large number of applications of power and high-power equipment put forward higher requirements for lithium-ion batteries. Traditional carbon materials can not meet the requirements of high performance lithium ion batteries. Only by exploring new energy storage materials can we break through the development bottleneck of lithium ion batteries. The graphite lamellar structure has a high degree of disorder and can provide more channels for intercalation and removal of lithium ions, which is beneficial to the improvement of the charge and discharge capacity, cyclic stability and performance of the lithium ion battery. In this paper, the preparation of spiral carbon nanofibers is studied. Using copper tartrate trihydrate as catalyst precursor and acetylene as carbon source, spiral carbon nanofibers were prepared by chemical vapor deposition. The spiral carbon nanofibers prepared at 480-680 鈩，

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