The impact of carbon shell on a Sn–C composite anode for lithium-ion batteries

Spherical Sn–carbon core-shell powders (CSCM/Sn) were synthesized through a resorcinol–formaldehyde microemulsion polymerization performed in the presence of SnO2 powders, followed by carbonization in an inert atmosphere. Scanning electron microscope and X-ray diffractometry analyses showed that the Sn powders were thoroughly encapsulated within the carbon microspheres. The CSCM/Sn presented much better cyclability than the conventional Sn–carbon microsphere composite. In core-shell-structured composite, most of the Sn particles were encased inside carbon microspheres and not easy to aggregate or fall off from the microspheres. The carbon shell suppressed the aggregation of tin particles and alleviated the volume change of tin, and the conductive carbon shell effectively decreased the polarization during cycling, giving rise to better high rate performance and excellent capacity retention ability. It is shown that surface structure plays an important role in alloy/C composite anode materials for lithium-ion battery.