Novel solvent-thermal preparation of a SnO2 nanoparticles/expanded graphite multiscale composite with extremely enhanced electrical performances for Li-ion batteries

Abstract

A novel SnO2 nanoparticles (NPs)/expanded graphite (EG) multiscale hybrid composite was prepared via an elaborately designed solvent-thermal reaction and the following anneal treatment. A mixed solvent system of acetone-H2O with volume proportion of 3:1 was employed for the solvent-thermal reaction in order to realize moderate hydrolysis rate of Sn4+ and favorable wettability between solvent molecules and EG surface. Acetone played a very positive role for the uniform nucleation and crystal growth of SnO2-NPs, which could be proved by the ultrafine sizes of 3–6nm and well-crystallized texture of SnO2-NPs, as well as their homogeneous anchor on the surface of EG. As an anode material for Li-ion batteries, the SnO2-NPs/EG composite exhibited excellent long-term cycling stability, e.g. decay-free reversible capacity of 976mAhg−1 after 100 cycles, and good rate capability (>400mAhg−1 at 2000mAg−1). The extraordinary electrochemical performances arise from the structural advantages of the composite: the ultrafine SnO2-NPs with high dispersity on conductive EG matrix supply not only large quantity of accessible active sites for lithium-ion insertion but also good conductivity and short diffusion length for lithium ions. These results suggest the SnO2-NPs/EG composite would be a promising candidate as anode material for next-generation LIBs.