▎ 摘　　要

The morphology of electrode materials plays an important role in determining the performance of lithium-ion batteries (LIBs). However, studies on determining the most favorable morphology for high-performance LIBs have rarely been reported. In this study, a series of F-doped SnOx (F-SnO2 and F-SnO) materials with various morphologies was synthesized using ethylenediamine as a structure-directing agent in a facile hydrothermal process. During the hydrothermal process, the F-SnOx was embedded in situ into the three-dimensional (3D) architecture of reduced graphene oxide (RGO) to form F-SnOx@RGO composites. The morphologies and nanostructures of F-SnOx, i.e., F-SnO2 nanocrystals, F-SnO nanosheets, and F-SnO2 aggregated particles, were fully characterized using electron microscopy, x-ray diffraction, and x-ray photoelectron spectroscopy. Electrochemical characterization indicated that the F-SnO2 nanocrystals uniformly distributed in the 3D RGO architecture exhibited higher specific capacity, better rate performance, and longer cycling stability than the F-SnOx with other morphologies. These excellent electrochemical performances were attributed to the uniform distribution of the F-SnO2 nanocrystals, which significantly alleviated the volume changes of the electrode material and shortened the Li ion diffusion path during lithiation/delithiation processes. The F-SnO2@RGO composite composed of uniformly distributed F-SnO2 nanocrystals also exhibited excellent rate performance, as the specific capacities were measured to be 1158 and 648mA h g(-1) at current densities of 0.1 and 5 A g(-1), respectively.