Preparation Of Si/c Cathode Materials By Metal Reduction For Lithium Storage Properties

With the popularity of electronic devices and the rise of electric vehicles,silicon materials with high theoretical capacity,environmental protection,non-toxicity and wide sources have attracted the attention of researchers.However,the high energy density of silicon makes its volume expand greatly in the charging and discharging process of lithium,which makes the material pulverize and affects the battery capacity and cycle retention rate.In this paper,different silicon-carbon composites were prepared by metal reduction,the main purpose of which was to reduce the preparation cost,simplify the experimental operation and improve the electrochemical properties of lithium anode materials.In this study,we first explored the preparation of nano-silica at room temperature,and then prepared nano-silicon material by metal reduction.The nano-silicon material is prepared by a simple and feasible method,and related performance tests are performed on the prepared material.During the experiment,it was found that there are a large amount of biomass diatomite raw materials in the natural world.By consulting the relevant literature,it was found that the reduction of silica by the low-temperature molten salt method can produce better economic benefits.The Si/C compound formed by coating with a carbon source then performs well in cycling stability and specific capacity at high current density.In our work,a simple and feasible test method was used to form a double template by mixing solution of hexadecyl ammonium bromide(CTAB)and triblock copolymer F127,and then silica was prepared by hydrolysis of ethyl orthosilicate(TEOS).The silicon oxide nanowires were prepared by adjusting the temperature and the amount of reactants,and the silicon nanowires were obtained by metal reduction of the silicon oxide nanowires.A series of related tests were carried out on the reduced nanowires.The results showed that the silicon nano wires prepared by magnesium thermal reduction at 700? had good lithium performance.After 100 cycles at a current density of 200mA/g,its reversible circulation capacity was still 1210.2mAh/g.In this paper,the effects of temperature,reduction time and other experimental conditions on the electrochemical properties of the product were investigated.Explore with silica and aluminium,anhydrous aluminium trichloride as reactants in different temperature,reduction time,the impact on the reduction product,after using different carbon sources on coated reducing product explores the influences of the reaction products,using SEM,TEM,XRD,TG,CV and other test methods under different conditions to explore the materials related to the morphology,crystal structure and lithium electricity performance.Experimental results show that in 300? after 12 h metal reduction can obtain better crystalline silicon material,through electrochemical performance test can be concluded that,under the condition of the reduction product under the current density of 200 ma/g,loop 200 times its specific capacity reached 1333.5 mAh/g,through ratio performance tests show that the product under 50 ma/g current density,the specific capacity of 2373.3 mAh/g,the electrode material in 200 ma/g under the current density,the specific capacity of 2115.7 mAh/g,the product under the current density of 500 ma/g,The specific capacity is 1772.1mAh/g,the electrode material at 1000mA/g current density,the specific capacity is 1397.2mAh/g,the electrode material at 2000mA/g current density,the specific capacity is 1009.8mAh/g,when the current density is adjusted again to 50mAh/g,its capacity is 2329.2 mAh/g,the maintenance rate is up to 98.1%.It was found that the electrochemical performance of silicon materials coated with asphalt was better when silicon materials were coated with different carbon sources at 300? for 12h reduction.TG tests showed that the silicon mass percentage and carbon mass percentage of the silicon-carbon composite were 47%and 53%respectively.The electrode material still had a specific capacity of 864.3mAh/g for 300 cycles at the current density of 1000mA/g.