SiC-Free Carbon-Silicon Alloys Prepared by Delithiation as Lithium-Ion Battery Negative Electrodes

Carbon-silicon alloys in different stoichiometric ratios are synthesized by delithiation of carbon-lithium-silicon ternary alloys with ethanol, followed by washing with HCl and distilled water. The as-prepared carbon-silicon materials are air- and water-stable. In contrast to mechanically milled or sputtered C-Si alloys studied in the past, the method of synthesizing C-Si alloys introduced in this work avoids the formation of inactive SiC even after 2 h of high-energy ball milling. This results in C-Si alloys with significantly greater volumetric and specific capacity. When cycled in Li half-cells, C-Si alloys exhibit good cycling performance and a lower volume expansion compared to conventionally made Si alloys. This is attributed to the presence of void spaces in the structure that can accommodate some of the Si volume expansion.