In situ polyol-assisted synthesis of nano-SnO2/carbon composite materials as anodes for lithium-ion batteries

Nano-SnO2/carbon composite materials were synthesized in situ using the polyol method by oxidizing SnCl2·2H2O in the presence of a carbon matrix. All the as-synthesized composites consisted of SnO2 nanoparticles (5–10 nm) uniformly embedded into the carbon matrix as evidenced by TEM. XRD confirmed the presence of nano-sized SnO2 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% SnO2) 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 SnO2 (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 SnO2 particles that are also better dispersed within the carbon matrix which also resulted in higher lithium storage capacity.