碳纳米管导电剂对硅复合电极初始裂纹的调控作用

REGULATION OF CARBON NANOTUBE CONDUCTIVE AGENT ON INITIAL CRACK OF SILICON COMPOSITE ELECTRODE

硅作为新型高容量锂离子电池最具潜力的负极材料,具有极高的能量密度。然而,硅材料在充放电过程中的巨大体积变形,导致电极的严重损伤和快速退化,使得硅基电池的循环寿命普遍较低,难以同时满足高容量与长寿命的设计要求,是高容量锂离子电池研发的核心难题。导电剂作为锂离子电池复合电极活性层的主要构成之一,传统上认为主要起到提高电极电导率的作用。通过研究导电剂(以碳纳米管为例)的组分含量,实验揭示了导电剂对硅复合电极的初始裂纹密度存在调控作用,得到了碳纳米管含量的最优值,并发现了碳纳米管的加入会引入缺陷的负面机制,此机制在电化学循环中也起到重要作用。以上实验结果对指导高容量长寿命硅复合电极的设计和制备具有重要意义。

Silicon is the most potential anode material for new high capacity lithium ion batteries with high energy density.However,the huge volume deformation of silicon materials during charging and discharging leads to severe damage and rapid degradation of electrodes,making the cycle life of silicon⁃based batteries generally low and difficult to meet the design requirements of both high capacity and long life,which is the core problem in the development of high⁃capacity lithium⁃ion batteries.As one of the main components of the active layer of lithium ion battery composite electrode,conductive agent is traditionally considered to improve the electrical conductivity of the electrode.By studying the component content of the conductive agent(taking carbon nanotubes as an example),the experiment revealed that the conductive agent has a regulating effect on the initial crack density of the silicon composite electrode,and the optimal value of the carbon nanotube content was obtained,and the negative mechanism by which the addition of carbon nanotubes introduces defects was discovered.This mechanism also plays an important role in electrochemical cycling.The above experimental results are of great significance for the design and preparation of high capacity and long⁃life silicon composite electrode.