| 초록 |
Ternary composites of reduced graphene oxide (RGO), SnO2 and carbon were synthesized at low temperature without heat treatment at high temperature. In the composites size of SnO2 nanoparticles are 2.5 nm. Graphene oxide was reduced to appreciable extent at this temperature by ascorbic acid which also serves as carbon source. The composites and the presence of carbon therein were proved through several techniques like, Raman spectroscopy, thermogravimetric analysis, transmission electron microscopy and energy dispersive X-ray analysis. The ternary composite shows specific capacity slight excess over the theoretical capacity (1493 mAh/g) of SnO2 at 100 mA/g after 100 cycles and a Coulombic efficiency ＞99%. Moreover, it displays good rate performance. Cyclic voltammetry proves that the conversion reaction (reduction of SnO2 with Li+ to produce Sn and the synchronous formation of Li2O) is reversible in the ternary composite whereas it is irreversible in SnO2 and binary composites. High specific capacity and good rate performance were attributed to the quantum dot sized SnO2 nanoparticles which shortens Li ion diffusion length, effective accommodation of volume change offered by RGO and carbon and reversibility of the conversion reaction. |
