Study On Preparation And Electrochemical Properties Of SiO Composite Anode Materials

With the development of lithium-ion batteries to electric/hybrid electric vehicles,aerospace and other large energy storage fields,graphite anode materials are difficult to meet people's demand for high specific capacity.Silicon-based anode materials have gradually entered people's field of vision due to its high specific capacity,among them,SiO is an amorphous structure,which can overcome the loss of capacity caused by silicon phase change during the first charge and discharge,and its volume expansion rate is less than that of silicon.However,the volume effect of SiO still exists in the process of cycling,which leads to the pulverization and fracture of the electrode active material,resulting in a sharp decline of specific capacity,and its low conductivity also limits the practical application of SiO.I n view of the above problems,the electrochemical properties of SiO materials can be improved through modification,carbon composite and auxiliary heat treatment.The research contents of this paper are as follows:a.Introducing phosphorus into SiO for ball milling,and then compounding them with carbon to preliminarily explore and analyze its electrochemical properties;b.Preparing SiO/C composite anode materials under different experimental conditions,and studying the influence of process parameters on their morphology and electrochemical properties;c.Reducing the heat treatment temperature and preservation time by means of auxiliary heat treatment,and exploring the influence of different proportion parameters on its morphology,structure and electrochemical properties.When the mass ratio of P and SiO is 1:1,the electrochemical properties of the prepared composite were optimal.After 80 cycles,it still remains a larger discharge specific capacity of 564.4 mAh/g with a higher capacity retention rate of 75.6%at the current density of 0.2 A/g.The mixture of PAN and SiO(PAN:SiO=3:7 wt%)was sintered at 600? for 5 h under Argon gas to obtain the composite,which shows the best electrochemical performance.Even 500 cycles,it still remains a larger specific capacity of 573mAh/g.The mixture of SiO and LiOH(SiO:LiOH=15:1 wt%)was sintered at 800? for 10 min under Argon gas to obtain the composite,which shows the best electrochemical performance.After 300 cycles,it still has the specific capacity of 640 mAh/g,showing excellent cycle performance.