The influence of graphene/carbon mass ratio on microstructure and electrochemical behavior in the graphene-SnO₂-carbon composite as anodes for Li-ion batteries

This paper reports a simplified one-step hydrothermal approach to prepare the graphene-SnO₂-amorphous carbon (Gr-SnO₂-C) composites which have a fixed SnO₂ content and various graphene to amorphous carbon (Gr/C) mass ratio as anode for Li-ion batteries. The Gr-SnO₂-C with a Gr/C mass ratio of 1:4 shows the best cycling stability at a current density of 300 mA g^-1. Then, at a low current density of 50 mA g^-1, it reveals a reversible capacity of around 878 mA h g^-1 after 50 cycles. By studying the microstructure evolution and electrochemical performance as a function of the Gr/C mass ratio, it is discovered that the Gr/C mass ratio can affect the Gr-SnO₂-C composites in the aspects of porous structures, conductivity of active materials and microstructural stability. The enhanced performance of the Gr-SnO₂-C composites is attributed to the synergism between the graphene, amorphous carbon and SnO₂ nanoparticles.