包覆型Si/C复合材料的制备及其性能研究

Preparation and Performance of Carbon-Coated Si/C Composites

分别采用球磨法和高温热解法制备了Si/C复合材料.XRD、SEM、电化学阻抗谱、循环伏安法和恒流充放电测试表征该Si/C复合材料的结构、形貌和电化学性能.结果表明,相比于球磨法,高温热解HDPE制备的Si/C复合材料颗粒形貌规则,碳的包覆较为均匀,导电性较好,阻抗较小.其首次嵌锂容量为4495 mAh/g,首次库仑效率65.3%,从第2周开始库仑效率都保持在97%左右,经过100次充放电循环后仍能达到438 mAh/g的可逆容量,具有较好的电化学循环稳定性.

The Si/C composite for lithium ion batteries was obtained by pyrolyzing and ball-milling.The microstructure and component of the composite was characterized by SEM and XRD,the electrochemical performance was investigated by electrochemical impedance spectroscopy（EIS）,cyclic voltammetry（CV） and galvano static charge-discharge tests.The results illustrate that the particle of Si/C composite prepared by pyrolysis exhibits inerratic morphology,uniform carbon-coating layer,good electrical conductivity,low resistance.The first intercalated-lithium capacity of the composite material is 4495 mAh/g;the first coulomb efficiency is 65.3%.From the second week the coulomb efficiency maintains 97%,and the capacity at the 100th cycle can retain 438 mAh/g.The Si/C composite has good electrochemical cycle stability.