硅/碳复合负极材料在18650型锂离子电池中的应用

Application of Si/C composite cathode materials in 18650 Li-ion cells

在研究硅/碳复合负极材料和人造石墨负极材料混合负极的比容量与电极膨胀率之间的变化关系的基础上,通过配方优化,成功制作了硅/碳复合负极材料与人造石墨负极材料混合负极的18650型锂离子电池。采用扫描电子显微镜法(SEM)、电化学交流阻抗频谱(EIS)等技术,分析了循环前后负极的变化,研究了氟代碳酸乙烯酯(FEC)添加剂对电池性能的影响。结果表明:FEC加入量较高时,可与硅负极材料形成更加稳定的SEI膜,抑制负极材料的粉化,电池180次循环后,容量保持率达到71.3%,循环性能得到显著提高。

The 18650 Li-ion cells with Si/C composite and artificial graphite blending cathode materials were fabricated successfully through composition optimization based on the study of relationship between specific capacity and swelling of Si/C composite. The change of cathode before and after cycle was analyzed through using SEM and EIS methods. The impact of FEC content on the performance of cells was investigated. The results show that FEC additive can notably improve the cycle life of 18650 U-ion cells. The capacity retention rate reaches 71.3% after 180% cycles, the improved performance attributed to stable solid-electrolyte interface （SEI） layers which suppressed surface pulverization of cathode materials.