Si@SiO2/N掺杂碳复合材料的制备及电化学性能研究

提出了一种核壳结构的Si@SiO_2@NC(NC为N掺杂碳)复合材料用于改善锂离子电池硅基负极材料在充放电过程中硅的体积膨胀和导电性差而导致的容量衰减等问题。该复合材料采用氧等离子体技术处理Si纳米颗粒的表面获得SiO_2层,然后在其表面碳化聚苯胺涂层获得N掺杂的无定形碳。SiO_2中间层具有可靠的缓冲效果和良好的机械支撑,可以在充放电过程中抑制Si纳米颗粒的体积膨胀,N掺杂的无定形碳可以用作电子和Li~+的快速传输通道。与Si纳米颗粒相比,Si@SiO_2@NC复合材料的首次放电容量可达2 583.1 m Ah/g,库仑效率为81%,在电流密度为200 m A/g时,循环40次后仍然具有1 015 m Ah/g的高可逆容量。

Preparation and Electrochemical Properties of Si@SiO2/N Doped Carbon Composites

A core-shell Si@SiO₂@NC (N-doped carbon) composite material is proposed for improving the performance of silicon-based lithium-ion battery resulting from the volume expansion and poor conductivity of Si during the charge and discharge processes. SiO₂ layer is prepared by treating the surface of Si nanoparticles with oxygen plasma, and N-doped amorphous carbon is obtained by carbonizing the polyaniline coating. The SiO₂ interlayer has a reliable buffer effect and good mechanical support to restrain the volume expansion of Si nanoparticles during charge and discharge processes, and N-doped amorphous carbon can serve as a fast transport channel for electrons and Li⁺. Compared with Si nanoparticles, Si@SiO₂@NC composites show a high initial discharge capacity of 2 583.1 mAh/g with Coulombic efficiency of 81% as well as a high reversible capacity of 1 015 mAh/g at a current density of 200 mA/g after 40 cycles.