Study On Preparation Process Of High Energy Density Lithium-ion Batteries Based On SiO/Graphite Composite Anode Materials

In recent years,consumers have higher and higher requirements for energy density and cycle life of lithium-ion batteries,which urgently requires the development of a new generation of anode materials with higher energy density than traditional graphite anodes.Silicon oxide（SiO）has been widely studied due to its high theoretical specific capacity,low lithium intercalation potential,and abundant natural resources.However,the volume change and poor electrical conductivity of SiO during cycling severely limit its commercial application.In this paper,SiO/graphite is used as the composite anode electrode materials,mainly from the three aspects of electrolyte,conductive agent and binder,to explore the influence of various variables on the performance of lithium-ion batteries,and to prepare a process system that matches these composite materials.The main research contents of this paper are as follows:（1）Research on the effect of electrolyte on the electrochemical performance of the batteries.Four different electrolytes were added to the button batteries and the soft-pack batteries respectively,and the electrochemical performance was tested.The results show that the batteries prepared with Tianci 8C electrolyte shows the best performance,The first charge specific capacity and first coulomb efficiency of the batteries are both 437.27 mAh g^-1and 91.80%,respectively.After 100 cycles of current density at 1 C,the capacity retention rate was 79.61%.The first discharge capacity of the soft-pack batteries is 1225.65 mAh,and the capacity retention rate after 500 cycles at 1 C current density is as high as 82.22%.（2）Research on the effect of conductive agent on the electrochemical performance of the batteries.The single conductive agent SP and the composite conductive agents SP+CNT,SP+Graghene and SP+CNT+Graghene were mixed with SiO/graphite composites to prepare button batteries and soft-pack batteries,and the electrochemical performance was tested.The results show that the cycle performance and rate performance of the composite conductive agent SP+CNT+Graghene are better.The effect of the addition ratio of CNT and Graghene on the performance of the batteries was further studied.The results showed that when the ratio of SP,CNT and Graghene was 92:4:4,the overall performance of the batteries was the best.The capacity recovery rate of the button batteries is 98.80%after being cycled at a high rate of 3 C.The capacity retention rate of the soft-pack batteries after 500 cycles at 1C is as high as 84.53%,and the capacity recovery rate after cycling at a high rate of 3C is as high as 96.33%,showing good reversibility.（3）The influence of the binder on the electrochemical performance of the batteries was studied.The conventional binder SBR+CMC,PAA and PAA+CMC were respectively made into button batteries and soft-pack batteries,and the electrochemical performance was studied.The results show that the batteries prepared by PAA+CMC has the best performance,with the most stable cycling performance at0.1 C,and the initial charge specific capacity is 442.83 mAh g^-1.The first discharge capacity of the soft-pack batteries is as high as 1242.87 mAh,the capacity retention rate after 500 cycles at 1 C is 84.30%,and the capacity recovery rate after cycling at a high rate of 3 C is 96.34%.