石墨载体对硅/炭复合负极材料性能的影响

Effect of graphite carrier on the properties of silicon/carbon composite anode materials

研究了人造石墨和天然石墨2种载体对所制备的硅/炭复合负极材料电化性能的影响。结果表明:石墨载体严重影响硅/炭复合材料的首次效率、容量、循环寿命和大电流充放电性能,采用人造石墨载体制备的硅/炭复合负极材料性能明显优于天然石墨。充放电曲线表明,第一个循环由于材料未活化,存在极化,放电电压平台较低;随着循环次数的增加,在活性物质表面形成SEI膜,阻碍锂离子的脱嵌,充放电曲线电压平台差扩大;随着充放电电流密度的加大,极化就越严重,充放电曲线电压平台差就越大。

The effects on the electrochemical properties of silicon/carbon composite anode materials by using artificial graphite and natural graphite as carrier were studied.It can be found that both the capacity and cycle life as well as the high current charge/discharge properties of silicon/carbon composites are seriously affected by graphite carrier.The properties of silicon/carbon composites with artificial graphite carrier are better than those of the natural graphite carrier.Discharge voltage platform of first cycle is low because of the polarization,which the materials have not been activated.The voltage platform difference between charging and discharging curves is enlarged with the increasing of cycles due to the formation of SEI films on the surface of active materials,which hinders the deintercalation of Li-ions.The polarization is more serious with the higher current density,therefore the difference between the charging and discharge curve voltage platform is greater.