Facile conversion of micron/submicron Si particles into Si/C composites with excellent cycle performance

Conversion of micron/submicron Si into Si/C composites as anode material for lithium ion battery (LIB) has received extensive attention. However, there is lack of simple methods for changing micron/submicron Si into Si/C composites with good long cycle performance (>550 cycles). In this study, micron/submicron Si was sequentially mixed with graphite (G) and glucose by ball milling, and then carbonized to yield Si@G-C composite. The proposed process for converting micron/submicron Si into Si/C is pretty simple, because it does not need complex synthesis steps, expensive carbon precursors, or special equipment. Most Si particles in this composite were covered by graphite and glucose-based amorphous carbon, which hindered contact of Si with electrolyte and enhanced material conductivity. Benefiting from this feature, the material showed a reversible specific capacity of 903.2 mAh/g after 700 cycles at 0.5 A/g current density, with capacity retention reaching 95.6 %. The long-cycle specific capacity exceeded the corresponding value of many micron/submicron-Si-based Si/C composites. The proposed simple method for preparing micron/submicron-Si-based Si/C was promising for industrial application. •A simple method was proposed to convert micron/submicron Si into Si/C composites.•The conversion contained no complex treatment steps.•The method did not need expensive carbon precursors or complicated equipment.•The obtained Si/C displayed superior specific capacity after 700 cycles.