Preparation And Study Of Silicon Carbon Composite Anode Material For Lithium Ion Power Battery

In recent years,the new energy power vehicle industry has ushered in considerable development,and the lithium-ion battery（LIB）anode material as a key component is developing to the direction of high energy density,low cost and environmental-friendly,and relevant researchers have made certain achievements.In this paper,using biomass rice husk（RHs）as raw material,first through ferric chloride（Fe Cl₃）to activate the RHs,through high temperature activation carbonization to obtain Fe₃O₄@C/Si O₂composite material,and then with phenolic resin（PF）and secondary combustion electrode waste（AG）coating modification,RH-PF and RH-AG composite materials are prepared.At the same time,the microstructure,pore structure and electrochemical properties of the obtained materials are investigated in depth.The specific research contents are as follows:1.Firstly,the rice husk is pretreated with deionized water and dilute hydrochloric acid to remove dust and other metal elements,and then the RHs is impregnated with Fe Cl₃of different molar concentrations.After activation and carbonization at different temperatures,the residue is removed with dilute hydrochloric acid and deionized water in turn.Finally,the porous Fe₃O₄@C/Si O₂composites were obtained by proper mechanical ball milling.the molar concentration of Fe Cl₃studied is 0M,0.5M,1M,2M and 4M,and the activation and carbonization temperature is 650℃,700℃and 750℃.After electrochemical testing and analysis,it is found that the optimal molar concentration is 2M and the optimal activation carbonization temperature is 700℃.At the current density of 0.1A.g^-1,the first specific discharge capacity of the electrode material is 1155 m Ah.g^-1,and the first Coulomb efficiency（ICE）is 55.4%.After 30cycles of charge and discharge,there is still a high specific capacity of 557m Ah.g^-1,with a capacity retention rate of 86.6%.2.In order to further improve the initial discharge ratio capacity of the Fe₃O₄@C/Si O₂composites,PF is used for coating modification.RH-PF composites are prepared from RHs and PF with different mass ratios and carbonization temperatures.After electrochemical testing and analysis,it is found that the optimal treatmentconditions are:the mass ratio is 1:1 and the carbonization temperature is700°C.At the current density of 0.1A.g^-1,the initial discharge capacity of the electrode material is 1383m Ah.g^-1and ICE is 47.5%.After 30 charge-discharge cycles,it is maintained at 467m Ah.g^-1,with a capacity retention rate of 67.6%.3.In order to better take into account the balance relationship among the specific capacity of initial discharge,ICE and capacity retention rate,PF is replaced by AG as the new coating agent.RH-AG composites are prepared by ultrasonic dispersion of different mass ratios of RHS and AG at different times.the mass ratio of the two is 2:1,1:1 and 1:2 respectively,and the ultrasonic sub-time is1h,2h and 4h.After electrochemical test and analysis,it is found that the optimal treatment conditions are:mass ratio is 1:1 and ultrasonic dispersion time is 2h.At the current density of 0.1A.g^-1,the initial discharge specific capacity of the electrode material under the optimal condition is 1017m Ah.g^-1.Although the capacity is slightly lower than that of Fe₃O₄@C/Si O₂,the ICE is as high as 62.3%.After 100 charge-discharge cycles,the reversible capacity of the electrode material can be stabilized at 562m Ah.g^-1.The capacity retention rate is 87.8%,showing a stable long cycle life.