In situ polyol-assisted synthesis of nano-SnO 2/carbon composite materials as anodes for lithium-ion batteries

Abstract

Nano-SnO 2/carbon composite materials were synthesized in situ using the polyol method by oxidizing SnCl 2·2H 2O in the presence of a carbon matrix. All the as-synthesized composites consisted of SnO 2 nanoparticles (5–10 nm) uniformly embedded into the carbon matrix as evidenced by TEM. XRD confirmed the presence of nano-sized SnO 2 particles that are crystallized in a rutile structure and XPS revealed a tin oxidation state of +4. Cyclic voltammetry of the composites showed an irreversible peak at 1.4 V in the first cycle and a typical alloying/de-alloying process at 0.1–0.5 V. The best composite (“composite I”, 15 wt% SnO 2) showed an improved lithium storage capacity of 370 mAh g −1 at 200 mA g −1 (∼C/2) which correspond to 32% improvement and lower capacity fade compared to commercial SnO 2 (50 nm). We have also investigated the effect of the heating method and we found that the use of a microwave was beneficial in not only shortening reaction time but also in producing smaller SnO 2 particles that are also better dispersed within the carbon matrix which also resulted in higher lithium storage capacity.