Three-dimensional porous carbon-coated graphene composite as high-stable and long-life anode for sodium-ion batteries

Sodium-ion batteries (SIBs) have been investigated as promising alternatives to lithium-ion batteries (LIBs) because of the rich sodium natural resource. Exploring suitable electrode materials is still a great challenge for the practical applications of SIBs. Herein, we demonstrate a novel three-dimensional porous carbon-coated graphene (3D PG@C) anode for SIBs using silica as the porous template combined with a subsequent polyaniline (PANI)-converted carbon coating. The synthesis process mainly consists of deposition of SiO₂nanoparticles on graphene surface, in situ polymerization of aniline monomers and carbonization of PANI and etching of SiO₂. The resultant 3D PG@C composite possesses high electrical conductivity, rapid ion insertion, sufficient active sites, short ionic diffusion distance and stable structural integrity for efficient Na-storage. As an anode material for SIBs, the 3D PG@C composite delivers excellent Na-storage performance, in terms of high initial discharge capacity (824 mAh g⁻¹at 50 mA g⁻¹), large reversible capacity and long cyclability (323 mAh g⁻¹after 1000 cycles at 1000 mA g⁻¹) and remarkable rate capability (207 mAh g⁻¹at 10000 mA g⁻¹). The design strategy reported in this work would provide a promising approach toward high-stable and long-life carbonaceous anode materials for SIBs.