锂离子电池SiO/TiH_(2)复合负极材料的制备及其电化学性能

Preparation and Electrochemical Performances of SiO/TiH_(2) Composite Anode Materials for Lithium-Ion Batteries

SiO材料具有较高的理论比容量、较低的电压平台以及比Si低的体积膨胀率,被认为是最具有商业化潜力的负极材料,但是SiO存在因初始库伦效率低、体积膨胀率高引起的循环快速衰减等问题。将SiO负极材料与钛氢化合物复合,采用简单、易于工业化的球磨和热处理方法制备了SiO/TiH_(2)负极材料,探讨了热处理温度与SiO和TiH_(2)的质量比对SiO/TiH_(2)复合负极材料的影响。结果表明,热处理过程中形成的高导电性中间相可以起到增强导电性、缓冲体积膨胀、显著改善复合负极材料循环和倍率性能的作用。其中热处理温度为700℃、质量比为4∶1的SiO/TiH_(2)复合负极材料的初始库伦效率为74.4%,100次循环后比容量为555.2 mA·h/g,比容量保持率为53.6%。

SiO material is considered as the most potential anode material for commercialization due to its higher theoretical specific capacity,lower voltage plateau and lower volume expansion ratio than that of Si.However,SiO has some problems,such as rapid cycle decay caused by low initial Coulomb efficiency and large volume expansion ratio.SiO anode material was combined with titanium hydrogen compound.The SiO/TiH_(2) anode material was prepared by ball milling and heat treatment.The method is simple and industrially achievable.The effects of heat treatment temperature and mass ratio of SiO and TiH_(2) on the SiO/TiH_(2) composite anode material were investigated.The results show that the highly conductive intermediate phases formed during heat treatment can enhance the conductivity,buffer the volume expansion,and significantly improve the cycle and rate performance of the composite anode material.The initial Coulomb efficiency of the SiO/TiH_(2) composite anode material reaches 74.4%at a heat treatment temperature of 700℃with the SiO/TiH_(2) anode material mass ratio of 4∶1.Its specific capacity retention rate is 53.6%after 100 cycles with a remaining specific capacity of 555.2 mA·h/g.