n型硅/碳复合材料的制备及电化学性能研究

Preparation and electrochemical performance study of n-type-Si/C composites

基于施主掺杂原理,制备了掺有微量磷元素的n型硅负极材料,为改善其循环性能,通过碳包覆的方法进一步制备了硅/碳复合锂离子电池负极材料。利用XRD、SEM、恒流充放电、交流阻抗谱(EIS)和循环伏安法(CV)等测试手段对所制n型硅及硅/碳复合材料的结构、形貌和电化学性能进行了表征分析。结果显示:所制n型硅具有与普通硅一致的晶体结构、良好的充放电平台、较高的容量以及很好的导电性,其电化学性能在碳包覆后有所改善,第一次放电比容量可达1 776.7 mAh/g,15次循环后仍可达1 000 mAh/g以上,库仑效率均保持在98%左右。

Based on the donor doping principle,phosphorus-doped n-type silicon anode material for lithium ion batteries was prepared.To improve the cycling performance of the n-type silicon anode material,n-type-Si/C composite anode material was prepared using the carbon coating method.The structure,morphology and electrochemical performance of the prepared n-type silicon and Si/C composite were characterized by using XRD and SEM and by performing constant current charge-discharge,electrochemical impedance spectroscopy（EIS） and cyclic voltammetry（CV） tests.The results show that the prepared n-type silicon possesses a same crystal structure to normal silicon,and shows a perfect charge-discharge platform,high capacity and good electrical conductivity.After coated with carbon,the electrochemical performance of the n-type silicon is improved.Its discharge capacity reaches 1 776.7 mAh/g in the first cycle and still remains at 1 000 mAh /g above after 15 cycles,while its coulomb efficiency is maintained at about 98%.