Superior lithium storage in a 3D macroporous graphene framework/SnO2 nanocomposite

Abstract

A three-dimensional (3D) interconnected graphene framework (GF)-based SnO₂ nanocomposite (3D SnO₂/GFs) was prepared using self-assembly of polystyrene (PS)@SnO₂ nanospheres and graphene oxide (GO) nanosheets under suitable pH conditions, followed by a thermal treatment. The electroactive material (SnO₂) is anchored to the wall of electrochemically and ionically conductive 3D interconnected GFs. When used as anodes for LIBs, the 3D SnO₂/GFs deliver an excellent reversible capacity (1244 mA h g⁻¹ in 50 cycles at 100 mA g⁻¹) and outstanding rate capability (754 mA h g⁻¹ in 200 cycles at 1000 mA g⁻¹). The ultra-small size of SnO₂ (sub 10 nm) and dimensional confinement of SnO₂ nanoparticles by the wall of GFs limit the volume expansion upon lithium insertion, and the 3D interconnected porous structures serve as buffered spaces during charge–discharge and result in superior electrochemical performance by facilitating the electrolyte to contact the entire nanocomposite materials and reduce lithium diffusion length in the nanocomposite.