The effect of annealing on a 3D SnO2/graphene foam as an advanced lithium-ion battery anode

Abstract

3D annealed SnO2/graphene sheet foams (ASGFs) are synthesized by in situ self-assembly of graphene sheets prepared by mild chemical reduction. L-ascorbyl acid is used to effectively reduce the SnO2 nanoparticles/graphene oxide colloidal solution and form the 3D conductive graphene networks. The annealing treatment contributes to the formation of the Sn-O-C bonds between the SnO2 nanoparticles and the reduced graphene sheets, which improves the electrochemical performance of the foams. The ASGF has features of typical aerogels: low density (about 19 mg cm-3), smooth surface and porous structure. The ASGF anodes exhibit good specific capacity, excellent cycling stability and superior rate capability. The first reversible specific capacity is as high as 984.2 mAh g-1 at a specific current of 200 mA g-1. Even at the high specific current of 1000 mA g-1 after 150 cycles, the reversible specific capacity of ASGF is still as high as 533.7 mAh g1, about twice as much as that of SGF (297.6 mAh g-1) after the same test. This synthesis method can be scaled up to prepare other metal oxides particles/graphene sheet foams for high performance lithium-ion batteries, supercapacitors, and catalysts, etc.