Production and characterization of carbon-silicon nanocomposite anode materials for secondary lithium batteries

Miser, Burcu
Amongst other anode materials, silicon has the highest capacity (for Li22Si5: 4200 mAh.g-1), whereas; the commonly used graphite has only a capacity of 320 mAh.g-1. Although this property of silicon makes it a worthwhile subject, there are technical issues which makes it difficult for commercial use. In this study, the aim is to investigate methods of producing silicon anode materials from a readily available powder via top down nano-particle forming methods for next generation lithium ion batteries which have higher capacity, longer cycle life, and are safer. These methods are high energy ball milling, metal assisted chemical etching, thermal plasma synthesis and sol-gel methods. Readily available silicon powder was converted into Si/C nanocomposite anode materials by using these methods and their electrochemical performances were tested. For this purpose, cycle life, impedance and power density of the cells were determined. According to the obtained results, the produced powders showed high capacity in the first few cycles and then lost their capacity. In particular, metal assisted chemical etching and induction plasma synthesis have yielded promising results to increase the cycle life of the readily available silicon powder. By applying these methods the surface area of silicon powder was increased from 2.4 m2.g-1 to around 7 m2.g-1. The sol-gel method selected for coating was not homogeneous and can not be obtained uniformly on all surfaces, so that it has not been successful in terms of cycle life increment except for ball-milled powder. 
Citation Formats
B. Miser, “Production and characterization of carbon-silicon nanocomposite anode materials for secondary lithium batteries,” Ph.D. - Doctoral Program, Middle East Technical University, 2017.