Ultrafine SnO 2 dispersed carbon matrix composites derived by a sol–gel method as anode materials for lithium ion batteries

Abstract

Ultrafine crystalline SnO 2 particles (2–3 nm) dispersed carbon matrix composites are prepared by a sol–gel method. Citric acid and hydrous SnCl 4 are used as the starting constituents. The effect of the calcination temperatures on the structure and electrochemical properties of the composites has been studied. Structure analyses show that ultrafine SnO 2 particles form and disperse in the disordered carbon matrix in the calcination temperature range of 500–800 °C, forming SnO 2/C composites, and the carbon content shows only a slight increase from 35.8 wt.% to 39.1 wt.% with the temperature. Nano-Sn particles form when the calcination temperature is increased to 900 °C, forming a SnO 2/Sn/C composite, and the carbon content is increased to 49.3 wt.%. Electrochemical testing shows that the composite anodes provide high reversible cycle stability after several initial cycles, maintaining capacities of 380–400 mAh g −1 beyond 70 cycles for the calcination temperature of 600–800 °C. The effect of the structure feature of the ultrafine size of SnO 2 and the disordered carbon matrix on the lithium insertion and extraction process, especially on the reversible behavior of the lithium ion reaction during cycling, is discussed.