Preparation and characterization of Si-based composite anode materials for Lithium ion batteries

• Main Authors: Yao-Sheng Huang, 黃堯聖
• Other Authors: Wei-Ren Liu
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/94015381441973464485

碩士 === 中原大學 === 化學工程研究所 === 102 === In this study, we used the pitch as the carbon source and Si/SiC as the active material, made the carbon layer coating on the surface of Si/SiC, to restrain the volume expansion of Si/SiC from outside. And also added the flake graphite before coating process, to buffer volume expansion of Si/SiC from inside. The characterization of the composite were carried out by XRD, FE-SEM, TEM and Raman, and electrochemical analysis were used to investigate the effect of operating parameters. For improvement of the cycle ability, we used the sodium alginate to replace the CMC as a new binder, and added the FEC (Fluoroethylene Carbonate) in our electrolyte, try to improve the cycle ability of Si-base anode material. At first, the effect of the conductive additives (CA) content, 30 wt%, 40 wt% and 50 wt% is checked and it was found that CA content has a profound effect on the cycle life of the electrode, which increased with increasing CA content. Then, we coated diffrenet ratio of carbon content on the surface of Si/SiC. The resulte is, if increased the content of carbon-coating layer on surface of Si/SiC, the volume expansion scale of Si/SiC would be smaller, after 100 cycles the capacity retention still had 32%. Hoping the capacity retention can be improved, we added the flake graphite with Si/SiC, and coated the carbon layer on these two materials' surface. After experiment, 4 (Si / SiC): 3 (flake graphite) is the best ratio that the capacity retention after 100 cycles improved to 60%. In carbonization temperature test, 1000℃ can make the degree of carbonization more completely. On the choice of binder, high porosity construct of sodium alginate's can buffer volume expansion of Si/SiC more effective than CMC-SBR. At last, the FEC addition is added in electrolyte, it was successful that improved the capacity retention to 90% after 160 cycles.