3D Graphene Encapsulated Hollow CoSnO Nanoboxes as a High Initial Coulombic Efficiency and Lithium Storage Capacity Anode.

3D Graphene sheets encapsulated amorphous hollow CoSnO nanoboxes (H-CoSnO @reduced graphene oxide [RGO]) are successfully fabricated by first preparing 3D graphene oxides encapsulated solid CoSn(OH) nanocubes, followed by an alkaline etching process and subsequent heating treatment in Ar. The hollow CoSnO nanoboxes with average particle size of 230 nm are uniformly and tightly encapsulated by RGO sheets. As an anode material for Li-ion batteries, H-CoSnO @RGO displays high initial Coulombic efficiency of 87.1% and large reversible capacity of 1919 mA h g after 500 cycles at the current density of 500 mA g . Moreover, excellent rate capability (1250, 1188, 1141, 1115, 1086, 952, 736, and 528 mA h g at 100, 200, 300, 400, 500, 1000, 2000, and 5000 mA g , respectively) is acquired. The reasons for excellent lithium storage properties of H-CoSnO @RGO are discussed in detail.