碳纳米管导电剂对硅碳负极锂电池性能提升的探索

Exploring mechanism of carbon nanotubes as conductive agent for improving performance of a silicon/carbon anode in LIB

锂离子电池已被广泛用于小型消费类电子、动力汽车和大型储能电网中。硅负极由于具有更高的比容量,是下一代锂离子电池最优选的负极。然而,硅材料较大的体积膨胀以及由此带来的颗粒粉化、材料与集流体剥离和不稳定的SEI阻碍了其大规模应用的进程。本试验以具有高电导率并且易形成导电网络的碳纳米管(CNTs)为导电剂,显著提升了电池的循环寿命(500周之后的容量保持率为92%)。通过微分电化学曲线、交流阻抗谱(EIS)、直流内阻(DCIR)、SEM和XPS测试分析发现,CNTs有助于解决氧化亚硅负极在循环初期由于导电性差导致的容量衰减问题,以及能够改善界面的稳定性,提升电池的综合性能。可以预见的是,CNTs对于提升其他电极材料的性能也会有一定的积极作用。

LIBs have been widely used in consumer electronics,electric vehicles,and large-scale energy storage grids.The next generation of LIBs,with silicon/carbon as the anode,will exhibit higher energy density.Nevertheless,the large volume expansion,the particle pulverization,the separation of the active material and the current collector,and the unstable SEI of the silicon anode hinder its largescale application.Here,carbon nanotubes(CNTs)with high conductivity and an easily formed conductive network are used as the conductive agent,significantly improving the cycle life of the battery(the capacity retention after 500 cycles is 92%).Through the differential electrochemical curves,EIS,DCIR,SEM and XPS,it is found that CNTs can limit the capacity degradation of an SiO anode in the initial several cycles by improving the conductivity of the battery and the stability of the interface.It can be predicted that CNTs will also play a positive role in improving the performance of other electrode materials in LIBs.