Preparation And Electrochemical Performance Of SiO Anode Materials For Lithium Ion Batteries

SiO,as an anode material,has become one of the research hotspots because of its high theoretical specific capacity,low price,and environmental friendliness.However,in the process of lithium deintercalation and intercalation,SiO may cause capacity attenuation due to volume effect and low conductivity,which limits the practical application of SiO.In this article,the electrochemical performance of SiO anode materials was studied from the aspects of electrode composition and material design,and the cycle performance was improved.Although the initial discharge specific capacity of the commercially available SiO reached 1994.5 mAh/g,the specific capacity decreased to 171.0 mAh/g after 10 cycles.Through ball milling and ultrasonic treatment of SiO,the initial discharge specific capacity was 2062.0 mAh/g,the coulomb efficiency was 61.5%,the specific capacity of the finer SiO can reach 949.9 mAh/g after 99 cycles,and the Coulomb efficiency was 99.8%.By comparing the cycle performance of the electrode preparation process(different electrode composition,coating thickness,prelithium treatment),the best electrode preparation process was obtained:the electrode composition ratio of active material,conductive agent,CMC,SBR was 68:20:9:3.Prelithium treatment significantly improved the first Coulomb efficiency but didn’t improve cycle performance.At different temperatures,different times and glucose concentrations,the carbon microspheres were composited on SiO by hydrothermal reaction.The initial specific discharge capacity of the material reached 2047.1 mAh/g and the coulomb efficiency was 63.5%after 100 cycles.The reversible specific capacity was 1194.4 mAh/g and the Coulomb efficiency was 99.8%.It showed that the composite carbon microspheres can effectively suppress the volume effect and improve the conductivity.SiO was used to composited with different contents of TiO2.The material with the least TiO2 content had the best performance.The initial discharge specific capacity was 1816.8 mAh/g,the Coulomb efficiency was 63.9%,and the reversible specific capacity was still 1035.0 mAh/g after 100 cycles,and the coulomb efficiency is 99.7%.It showed that the TiO2 composite had no improvement in comparison capacity and circulation.The composite treatment of carbon microspheres and TiO2 also failed to achieve the desired results.When using the flake graphite composited with different contents of SiO,and the graphite content was 20%,the performance was the best.The initial discharge specific capacity was 1906.0 mAh/g,the Coulomb efficiency was 60.6%,and the reversible capacity was still maintaining 1046.3 mAh/g after 100 cycles,the Coulomb efficiency was 99.7%.The results showed that the flake graphite composite can significantly improve the electrochemical performance of SiO,and significantly improved the specific capacity fluctuation of SiO due to the volume effect.Hydrothermal reaction was used on SiO-graphite-composite materials to coat the SiO surface with carbon as much as possible.The initial discharge specific capacity is 1405.6 mAh/g.After the material reaches a low rate of 250 mA/g after a high power test up to 1600 mA/g,the material can continue its stable cycle,and its specific capacity remained 802.0 mAh/g after 100 cycles.This showed that the combination of the two treatment methods can improve the cycle stability of the material.