Study On Silicon And Activatied Carbon Materials For Electrochemical Energy Storage

Lithium-ion batteries and super capacitors are two most promising electrochemical energy storage devices. And the most effective way to improve its performance is to develop new materials. Silicon is an important lithium-ion battery anode material. In this paper, one kind of butyl-coated silicon nano-materials was prepared by the certain original liquid phase synthesis, then the carbon-coating silicon nanomaterials was prepared after high-temperature sintering, and took related tests of physical characterizations and electrochemical performances. Active carbon is a kind of good super capacitor electrode. This article used petroleum coke as the carbon source; and prepared a carbon material witn high surface area by activation of sodium hydroxide. Explore the assembly process of super capacitors, and study the relationship between different preparation conditions and material properties.Firstly, in this paper, it optimized the experimental conditions gradually, to prepare one kind of butyl-coated silicon nano-materials with proper size, and uniform distribution. After tests founded that its size was about 50nm with excellent distribution. Took a further process of high-temperature sintering in a tube furnace, the materials got shaw a good cycling properties, the maximum specific capacity of lithium-extracted was 410.31mAh/g. The gasification loss of active materials could be improved effectively through the method of vacuum sintering, by which obtained the silicon-coated carbon nano materials of better electrochemical properties and carbon-coating equably. Its maximum specific capacity of lithium-extracted reached to 663.25mAh/g, with excellent cycling properties and no obvious capacity attenuation after 70 cycles.Secondly, The study of the influences of silicon material in different binder systems was carried. Which revealed the nature of how the binder affect battery performance. Discovered that cycle properties of pure silicon could be improved when using CMC of water-based adhesive system instead of the traditional PVDF. However, when applied in carbon-coating silicon nano-materials PVDF is better.Finally, studied the electrochemical properties of the super capacitors when using activatied carbon as electrode materials. Revealed the relationship between the structure of the materials and its performance. Using petroleum coke as the carbon source, activation at 700℃with NaOH, the specific capacitance of the activatied carbon got under 1mV/s was 68.78F/g. The retention efficiency under 100mV/s was 47.52%. However, the activation process before joining hydrogen peroxide to pre-oxidation can improve the carbon material's performance significantly. The specific capacitance under 1mV/s reached to 83.47F/g. It still remained 68.75F/g under 100mV/s. The retention efficiency was 77.57%.