Dual-Phase SiC + C Coated Microsize Si@SiO<sub><i>x</i></sub> Powder as Anode Material for Li-Ion Batteries
Shuai Wang, Qinyu Wu, Zhenfei Cai, Ziyang Ma, Zishan Ahsan, Yichun Li, Yangzhou Ma, Guangsheng Song, Weidong Yang, Cuié Wen
Abstract
Severe volume expansion and poor ionic transport greatly impede the further application of micro-Si anodes despite their high energy density and low processing cost. To address these challenges, we propose a Si/C composite anode (denoted as WM-30C). In this design, wet milling introduces an oxide layer as the core, while high-temperature heat treatment with bitumen regulates the silicon valence state and introduces a strong Si–C bond, forming the shell. In this design, during the wet milling process of micro-Si, a layer of oxide is introduced in situ on the surface to form Si@SiO 2 as the core. The high-temperature heat treatment is then employed to adjust the valence state of silicon, and in conjunction with bitumen, strong Si–C bonds are introduced, ultimately forming the shell layer. As a result, the WM-30C composites exhibit an impressive initial Coulombic efficiency of 83.4% and high rate performance. Furthermore, they maintain a steady cycling rate of 614 mA h/g (0.2C) for 325 cycles and nearly negligible capacity degradation at a constant capacity of 600 mA h/g. These results highlight the significant improvement in electrochemical properties achieved by incorporating a multiphase structure (SiO x + SiC + C) through a cost-effective wet chemical reaction of silicon and a bitumen heat treatment process in micro-Si-based composites.