Building high-rate silicon anodes based on hierarchical Si@C@CNT nanocomposite

In order to achieve a high rate silicon (Si) anode for lithium-ion batteries, a nanostructured Si@C@CNT composite with multistage conductive networks and interpenetrating voids is designed and fabricated by a spray drying approach, which could obviously improve the electronic/ionic conductivity, and effectively release the strain generated during Li⁺ intercalation/de-intercalation into/from Si, thereby leading to a high-rate (620 mA h g⁻¹ at 7.5 A g⁻¹) and stable Si anode. For actual applications, Si@C@CNT-PG (porous graphene) electrode has been built by simple mixing of the Si@C@CNT nanocomposite and home-made PG at the weight ratio of 2:8 as the active material, which exhibits the overwhelming electrochemical performances: the reversible capacity reaches 600 mAh g⁻¹ at 4 A g⁻¹; moreover, 80% of the initial capacity is still attained after charge/discharge at 800 mA g⁻¹ for 200 times.