Aluminothermic reduction synthesis of Si/C composite nanosheets from waste vermiculite as high-performance anode materials for lithium-ion batteries

The utilization of mining wastes for value-added energy applications is vitally important in a clean and sustainable society. In this work, we report the preparation of nanostructured Si/C composites from a vermiculite waste via an aluminothermic reduction reaction. During the preparation process, chitosan is employed as the carbon source which can intercalate into the interspacing between the layers of vermiculate through cation exchange, which is the key to form a layered Si/C composite. Such obtained Si/C composites exhibit layered structure, large specific surface area, abundant nanopores, and minor SiOx and N components, thus having the merits of buffering volume expansion, good structure stability and high electrical conductivity. Finally, the Si/C composites are applied as anode for lithium-ion batteries and shows excellent specific capacity of ~948 mAh g−1 after 350 cycles at 1.0 A g−1 with a capacity retention of 85%, proving the applicability of such Si/C composite as an alternative to commercial graphite anode. This work not only provides a mild route for designing nanostructured Si/C composite anode materials, but also paves an innovative way for the reutilization of waste tailings for high value-added materials applications.