Preparation And Modification Of SiO_x Composite Anode Materials For Lithium Ion Batteries

SiO_x-based anode materials are considered to be one of the promising anode materials in the next generation of commercial lithium-ion batteries.This article aims at the fact that the volume effect of SiO_x-based anode materials in the charge and discharge process is more serious.After a long time cycle,the material will be powdered and broken,resulting in a rapid decrease in cycle life and poor intrinsic electronic conductivity.The double coating of amorphous carbon and Li₃BO₃,the use of CNTs and metal Sn to build a three-dimensional conductive network structure,and the preparation of Ni-MOF porous materials are used to improve the cycle stability and rate performance of the material.The main contents are as follows:(1)SiO_x@C@Li₃BO₃composite material was successfully prepared by using the improved Stober liquid phase method,using TEOS as raw material,compounding with sucrose and Li₃BO₃through high-temperature treatment.The results show that the prepared SiO_x@C@Li₃BO₃has a uniform structure,which is composed of carbon matrix and SiO_xparticles with Li₃BO₃coating layer.The carbon material effectively improves the cycle stability and rate performance of the composite material.The Li₃BO₃which was introduced effectively improves the interface stability of the material.The first reversible capacity of the composite under the optimized conditions is 629.1 m Ah g^-1,and the capacity retention rate after 100 cycles is 78.1%.(2)CNTs was used as a flexible conductive network,and metal Sn was introduced for compounding,the SiO_x/CNTs/Sn composite material with a 3D network structure was successfully prepared.CNTs construct a flexible conductive network with good mechanical properties for SiO_x,effectively alleviating the volume effect of SiO_xmaterials,and improving the cycle stability of the materials.The synergistic effect of CNTs and metal Sn effectively improves the conductivity of the composite material and effectively improves the rate performance of the material.The initial reversible capacity of the composite under optimized conditions is 658.2 m Ah g^-1,and the capacity retention rate is as high as 93.7%after 100 cycles.(3)The Ni-MOF precursor material was prepared by the liquid phase method,and the SiO_xprepared by the improved Stober liquid phase method was loaded on the Ni-MOF material,and the SiO_x@Ni-MOF composite material was successfully prepared.The results show that SiO_xparticles are uniformly distributed on the derived framework of Ni-MOF material.Ni/Ni O and derived frameworks in Ni-MOF materials can effectively improve the electronic conductivity of the material and provide a stable structure to suppress the volume change of the material.Under the optimized conditions,the first reversible capacity of the composite is 1065.5 m Ah g^-1,and the capacity retention rate is 60.4%after 200 cycles.The material exhibits good cycle stability and excellent rate performance.After the carbon coating treatment,the electrochemical performance of the composite material is further improved,and the capacity retention rate is as high as 78.3%at a current density of 1 A g^-1for 450cycles.