Preparation And Properties Of High Specific Energy Silicon-Carbon Composite Anode Materials For Lithium Ion Batteries

Under the pressure of increasing environmental pollution and depletion of petroleum resources,it has become an urgent need for humans to find a new green renewable energy source to replace the existing fossil energy system.Due to its many advantages,lithium-ion batteries have been widely used in humans in just ten years since they were successfully commercialized in 1991,considered to be the most effective way to solve the double crisis of human energy and the environment.Although after 20 years of research and development,the current commercial application of lithium-ion batteries still uses graphite as the battery anode material,which hinders the further capacity of lithium-ion batteries.Improve,because of the low specific capacity of the graphite-based negative electrode material.Therefore,in order to improve the specific capacity of existing lithium-ion batteries and apply them in more fields to completely solve environmental and energy problems,it is necessary to improve the existing graphite negative electrode system.Therefore,in order to improve the specific capacity of existing lithium-ion batteries and apply them in more fields to completely solve environmental and energy problems,it is necessary to improve the existing graphite negative electrode system.After more than 20 years of development,the researchers found the silicon-based anode of the negative electrode material with the highest specific capacity,but the silicon anode has many disadvantages such as large volume expansion,poor cycle stability,and unstable SEI film.Therefore,the researchers want to combine the graphite anode material and the silicon-based anode material,combined with the electrochemical stability of the graphite anode material and the high specific capacity of the silicon-based anode,to produces the next-generation lithium ion anode material with perfect properties.In order to research the preparation process,composition,and electrochemical performance of the existing commercial silicon carbon anode materials on the market,this paper prepare four kinds of silicon carbon anode materials from mainstream silicon carbon anode manufacturers.Through series of characterization methods and electrochemical performance tests,the experimental variables are strictly controlled for comparison experiments.We have found that the existing commercial silicon-carbon anode materials are mainly prepared by mechanically compounding nano-sized silicon particles or silicon monoxide particles with graphite or amorphous carbon,in which silicon accounts for 3% to 50%.Etc.However,when the proportion of silicon is too high,the cycle stability and rate performance of the negative electrode are significantly deteriorated.In order to further explore the influence of existing mainstream binders on the properties of silicon-carbon anode materials with different mass ratios,this paper sets up an orthogonal experimental group and does a lot of basic experiments to explore the preparation process of different binders in silicon-carbon composite anodes.The results show that when the silicon content is less than 5%,the water-based bonding using CMC+SBR can effectively ensure the first effect and cycle stability of the electrode,and when the silicon content exceeds 20%,the oil-based bonding using PAA+NMP.The agent can significantly improve the first effect and reversible specific capacity of the electrode.