锂离子电池硅/石墨烯负极材料的电化学性能

Electrochemical Performance of Silicon/Graphene Nanocomposites Anode Materials for Lithium-ion Batteries

采用高能球磨法制备了纳米硅/石墨烯(Si@G)复合锂离子电池负极材料,并研究了高能球磨时间对Si@G复合材料成分和电化学性能的影响。X射线衍射分析结果表明:球磨40 min后,产物中出现少量电化学惰性的碳化硅。球磨20 min的Si@G复合材料具有最高的首次放电比容量(3 418 mA?h/g)和首次Coulomb效率(89%),但其充放电循环稳定性较差,放电比容量在33次充放电后即衰减为首次的80%。而球磨40 min的Si@G复合材料,充放电84次后,其容量保持率仍为80%。表明没有储锂容量的杂质相SiC虽然导致Si@G负极材料的首次充放电比容量下降,但有利于提高充放电循环稳定性。

Silicon/graphene composites(Si@G)anode materials for lithium-ion battery were prepared via high-energy ball milling.The effect of milling time on the composition and electrochemical performance of Si@G composites was investigated.Based on the analysis by X-ray diffraction,a small amount of electrochemically inert silicon carbide(SiC)is formed at milling time of 40 min.The Si@G composite produced by miling for 20 min has the optimum initial specific discharge capacity(i.e.,3 418 m A?h/g)and the first coulombic efficiency(i.e.,89%),with 80%of the initial specific discharge capacity retained after 33 charge–discharge cycles.The Si@G composite produced by milling for 40 min is charged and discharged for 84 times,and its capacity retention rate is still 80%.This indicates that SiC shows no lithium storage capacity,resulting in a decrease in the first specific charge–discharge capacity.However,SiC can improve the cycling stability of Si@G composite anode materials.