Fluorine-Doped SnO₂@Graphene Porous Composite\nfor High Capacity Lithium-Ion Batteries

Abstract

For the first time, a composite of\nfluorine-doped SnO₂ and reduced graphene oxide (F-SnO₂@RGO) was synthesized\nusing a cheap F-containing Sn source, Sn­(BF₄)₂, through a hydrothermal process. X-ray photoelectron spectroscopy\nand X-ray diffraction results identified that F was doped in the unit\ncells of the SnO₂ nanocrystals, instead of only on the\nsurfaces of the nanoparticles. F doping of SnO₂ led to\nmore uniform and higher loading of the F-SnO₂ nanoparticles\non the surfaces of RGO sheets, as well as enhanced electron transportation\nand Li ion diffusion in the composite. As a result, the F-SnO₂@RGO composite exhibited a remarkably high specific capacity\n(1277 mA h g^–1 after 100 cycles), a long-term cycling\nstability, and excellent high-rate capacity at large charge/discharge\ncurrent densities as anode material for lithium ion batteries. The\noutstanding performance of the F-SnO₂@RGO composite electrode\ncould be ascribed to the combined features of the composite electrode\nthat dealt with both the electrode dynamics (enhanced electron transportation\nand Li ion diffusion due to F doping) and the electrode structure\n(uniform decoration of the F-SnO₂ nanoparticles on the\nsurfaces of RGO sheets and the three-dimensional porous structures\nof the F-SnO₂@RGO composite).