Synthesis of tin-encapsulated spherical hollow carbon for anode material in lithium secondary batteries.

The tributylphenyltin (TBPT)-encapsulated resorcinol (R)-formaldehyde (F) sol was prepared inside the micelles of cetyltrimethylammonium bromide (CTAB). This core-shell-type sol was polymerized and further carbonized to obtain nanosized Sn-encapsulated spherical hollow carbon. The size of spherical hollow carbon and Sn metal particles was controllable by changing the R/CTAB or TBPT/CTAB mole ratio, respectively. It is likely that, when tested as the anode in Li secondary batteries, the spherical hollow carbon acts as a barrier to prevent the aggregation of nanosized Sn particles and provides a void space for Sn metal particles to experience a volume change without a collapse of carbon shell, giving rise to a better cycle performance than that of pure Sn metal.