基于PAN前驱体不同热处理温度制备NCFs及在锂硫电池中的电化学行为

The electrochemical behavior of nitrogen-doped carbon nanofibers derived from a polyacrylonitrile precursor in lithium sulfur batteries

  • 摘要: 基于电纺聚丙烯腈(PAN)前驱体制备三维氮掺杂炭纳米纤维(NCFs)自支撑集流体,以Li2S6溶液为活性物质,研究了不同热处理温度下制备的NCFs理化性能及其在锂硫电池中的电化学行为。结果表明,热处理温度为900 ℃时,制备的NCFs(NCFs-900)表现出优异的电化学性能。当载硫量为4.19 mg·cm−2时,NCFs-900@Li2S6电极在0.2 C下,初始放电容量为875 mAh·g−1,经250周循环后仍有707 mAh·g−1,库伦效率为98.55%。同时在高倍率1 C下循环150周后容量保持率为81.53%。

     

    Abstract: A 3D assembly of nitrogen-doped carbon nanofibers (NCFs) derived from polyacrylonitrile was synthesized by a combined electrospinning/carbonization technique and was used as the positive current collector in lithium sulfur (Li-S) batteries containing a Li2S6 catholyte solution. The physical and electrochemical behavior of the NCFs were investigated and it was found that their electrochemical performances depended on the pyrolysis temperature. Of the samples carbonized at 800, 900 and 1 000 °C, those carbonized at 900 °C performed best, and delivered a reversible capacity of 875 mAh•g−1 at a high sulfur loading of 4.19 mg•cm2 and retained at 707 mAh•g−1 after 250 cycles at 0.2 C. The coulombic efficiency of the NCF-900@Li2S6 electrode was almost 98.55% over the entire cycle life. In addition, the capacity retention of the electrode reached 81.53% even at a high current density of 1 C for over 150 cycles. It was found that the NCFs carbonized at 900 °C had the highest electrical conductivity, which might be the dominant factor that determined its performance for use as a positive current collector.

     

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