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.