Preparation of Carbon-Silicon Composite from Silicon Slurry Waste and Its Surface Properties

• Main Authors: Yu-Cheng Hsiao, 蕭裕誠
• Other Authors: Tzu Hsuan Tsai
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/cv7ah2

碩士 === 國立臺北科技大學 === 資源工程研究所 === 106 === In the wafer cutting process, a large amount of waste sludge is generated. If it can be effectively recycled and reused, not only the processing cost, but also the waste will be reduced significantly. The carbon-silicon composite (C/Si) has been considered as the most promising anode materials for lithium ion batteries due to its high capacity. However, the poor conductivity of silicon and the large volume change during charge-discharge cycling limit its practical applications. In order to overcome the limitations of anodes with Si, preparing C/Si composite with high specific surface areas and good conductivity is critical. In this study, silicon powders recovered from the silicon slurry waste was used to prepare C/Si composite with high specific surface areas and conductivity. During the pretreatment process of silicon slurry wastes, the cutting solution was washed using acetone and removed with centrifugation. Then, the ball milling technology was used for miniaturization of silicon particles, the main size of silicon powder decreased to 43.82 nm after milling with ZrO2:Si=5:1 at 400 rpm for 20 hr. After ball milling, C/Si composite was synthesized by hydrothermal method (180°C, 12 hr) from the ball-milled silicon powder and glucose. The effects of various operation parameters on the structure of C/Si composite were discussed in this study. The synthesized Si-C composite was then used to make an electrode, and its surface property and electrical double layer capacitance were measured by electrochemical techniques including cyclic voltammetry and impedance spectroscopy. Both of the electrochemical methods provided the similar values in electrical double layer capacitance. Comparing with the results, C/Si composite after carbon dioxide activation owns higher specific capacitance, showing a higher specific surface area. This study provides the experimental analysis about the pretreatment of silicon slurry waste, ball milling, the formation of C/Si composite and the electrochemical measurement of electric double layer capacitance; in addition, the evaluation of the specific surface area corresponding to the electric double layer capacitance was also discussed.