Chemically activated graphene/porous Si@SiOx composite as anode for lithium ion batteries

•Chemically activated graphene encapsulated porous Si composite was prepared.•The graphene offers a continuous electrically conductive network.•The porous structure can accommodate volume expansion of Si-based materials.•The composite exhibits excellent lithium storage performance.

Chemically activated graphene/porous Si@SiOx (CAG/Si@SiOx) composite has been synthesized via magnesiothemic reduction of mesoporous SiO2 (MCM-48) to porous Si@SiOx and dispersing in the suspension of chemically activated graphene oxide (CAGO) followed by thermal reduction. The porous Si@SiOx particles are well encapsulated in chemically activated graphene (CAG) matrix. The resulting CAG/Si@SiOx composite exhibits a high reversible capacity and excellent cycling stability up to 763 mAh g−1 at a current density of 100 mA g−1 after 50 cycles. The porous structure of CAG layer and Si@SiOx is beneficial to accommodate volume expansion of Si during discharge and charge process and the interconnected CAG improves the electronic conductivity of composite.