Shell-by-Shell Synthesis and Applications of Carbon-Coated SnO2 Hollow Nanospheres in Lithium-Ion Battery

SnO2 hollow nanospheres were synthesized from glucose and SnCl2 solution under hydrothermal environment and calcinations. The carbon layer was then deposited as a buffer layer via hydrothermally treated glucose solution. The thickness of the SnO2 shell in the hollow structures could be adjusted by changing the concentration of the SnCl2 coating solution. The crystalline structure and morphological observation of the as-synthesized hollow structures were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The thickness of SnO2 under 0.1 and 1 M SnCl2 coating solution was 15 and 60 nm, respectively. It was demonstrated that the electrochemical performance was significantly improved by the hollow structure and strongly affected by the shell thickness of SnO2. The hollow structure with 15 nm in SnO2 thickness exhibited an outstanding reversible capacity of 500 mA hg(-1) at 5 C. The extraordinary performance should be associated with the ultrathin SnO2 shell and the carbon layer, which could accommodate the volume changes and prevent the agglomeration of Sn particles during cycling.