Porous SnO2/Graphene Composites as Anode Materials for Lithium-Ion Batteries: Morphology Control and Performance Improvement

The rational design of graphene-encapsulated nanomaterials is of great significance to the high-rate and long-cycle anode materials in lithium-ion batteries. Herein, composites of three-dimensional reduced graphene oxide-encapsulated SnO2 nanoparticles (SnO2/RGO) have been synthesized by combining hydrothermal treatment with spray drying or freeze drying, and finally calcination. The morphology of a SnO2/RGO composite can be controlled and SnO2/RGO microspheres obtained by spray drying possess a large specific surface area and abundant inner spaces. Such kinds of morphology and porosity characteristics cannot only provide sufficient interior void to buffer the large volume variation but also provide an effective contacting area of electrolyte with electrode materials and more active sites for a redox reaction, which effectively avoids shedding of active components during lithiation/delithiation. The obtained SnO2/RGO shows a high specific capacity of 1592 mA h g–1 after 500 cycles at 500 mA g–1, and it can maintain 319 mA h g–1 even at 5 A g–1.