In order to improve the cycle stabilities of tin based anode materials and keep their high capacities

Sn/C composites with different carbon contents were prepared by disperse polymerization and pyrolysis of poly(para-divinyl benzene)encapsulated tin dioxide nanoparticles.The morphologies of Sn/C composites were analyzed by means of transmission electron microscope (TEM) and powder X-ray diffraction (XRD).Tin-based particles(about 100 nm) can be uniformly distributed in carbon matrix when the carbon content in composite exceeded 50 wt%.With the decrease of carbon content

the aggregation of tin oxides became serious for no enough carbon as barrier

and the diameter of tin based particles increased.During the pyrolysis of poly(para-divinyl benzene)

part of SnO2 was reduced into metallic tin and SnO

and as the carbon content in composite increased

the degree of reduction increased.The electrochemical performances of Sn/C composites as electrodes were compared.Electrochemical performances of the Sn/C composite depended on morphologies of tin and carbon phases.The reversible capacities of Sn/C composites increased with the decrease of carbon content because the pyrolyzed carbon showed a low reversible capacity.On the other hand

the cycle ability of Sn/C composites increased as the carbon content increased because the carbon effectively suppressed the sintering agglomeration of tin based material and maintained the electrical conductivity of composites.Further

the morphologies of electrodes were analyzed by SEM and XRD.With the increase of carbon content

the electrochemical sinter of tin based material in electrode was inhibited.The different morphologies of various electrodes were consistent with their different cycle performances.According to the analysis results of morphologies and properties of Sn/C composites

stable electrochemical performances of the Sn/C composites can only be achieved by homogeneous dispersion of the tin-based particles in carbon matrix so as to avoid aggregation of tin and its pulverization and to keep conductivity of the Sn/C composites.