Reduced Graphene Oxide Wrapped Si/C Assembled on 3D N-Doped Carbon Foam as Binder-Free Anode for Enhanced Lithium Storage

Three-dimensional (3D) and flexible N-doped carbon (NC) foam was prepared by the carbonization of low-cost and commercial melamine foam. Flexible reduced graphene oxide wrapped Si/C assembled on N-doped carbon (Si/C/RGO/NC) foam was further prepared by the pyrolysis of the Si/polyvinyl alcohol/graphene oxide coated on the melamine foam. The polyvinyl alcohol enhances the bonding strength of Si and melamine, which ensures the uniform distribution of Si in the 3D NC foam after the pyrolysis process. The NC foam and composited reduced graphene oxide (RGO) in the electrode as continuous conductive frameworks and elastic matrix can maintain the structural integrity, improve electron and ion transport and accommodate the severe volume change of Si-based electrode. Double carbon layers (amorphous carbon and RGO) coated Si core can effectively protect the Si core and avoid the direct contact between Si and electrolyte. The flexible 3D Si/C/RGO/NC foam with -40 wt% Si as freestanding anode for lithium ion batteries exhibits a high reversible capacity of 740 mAh g(-1) after 100 cycles at 100 mA g(-1) and 314 mAh g(-1) after 500 cycles at 1 A g(-1) (based on the weight of the composite), along with excellent rate capability and cycling stability.