Effect of asphalt-decomposed soft carbon on the performance of Si-based anode material in lithium ion battery
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摘要: 以沥青为软碳原料(质量分数为10%、20%、30%、50%),通过高温热解法成功合成了不同软碳含量的碳/硅(C/Si)复合材料。实验结果表明,软碳材料的引入能有效抑制Si基材料的体积效应和提高其电子电导率,从而在极大的改善负极材料循环性能的同时,还提高了其比容量。其次,通过系统研究不同C含量的C/Si复合材料性能,发现最佳的沥青加入量为20%。该条件所合成样品具有高达2356.7 mAhg-1的首次充电比容量和86.6%的库伦效率。经过50次循环后依然有726.4 mAhg-1的充电比容量,远高于工业化石墨负极材料,应用前景广阔。本研究还详细研究和讨论了软碳材料的形成机制以及不同软碳含量对材料形貌的影响。Abstract: The silicon (Si) was mixed with different amounts of asphalt (0%, 10%, 20%, 30% and 50% in mass fraction) as the soft carbon (C) source, respectively, to form the C/Si composites via the thermal decomposition method. As a result, the volume expansion of the Si material during the insertion/deinsertion process is effectively supressed, and the electric conductivity is improved at the same time, leading to the cycling stability and specific capacity increasing. For instance, a first-charge capacity as high as 2 356.7 mAhg-1 is achieved for the C/Si sample synthesized using 20% asphalt. After 50 cycles, 726.4 mAhg-1 of the capacity is retained, which is much higher than that of the commercial graphite and promising for industrial application. Moreover, the synthesis mechanism and effect of different amounts of asphalt on the morphology of obtained materials were also discussed.
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Key words:
- lithium ion battery /
- anode material /
- C/Si composite /
- soft carbon /
- asphalt
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