Synthesis of Si/C Composites by the Co-Carbonization of Phenolic Resin with Various Polysilane Polymers and Their Application to the Anode Material for Li~+ Batteries

摘要

Si/C composites were synthesized by the co-carbonization of 3,5-xylenol-derived novolac resin with various polysilane polymers. A significant increase in the Li~+ reversible capacity due to the inclusion of Si in the C matrix was observed. However, the Li~+ irreversible capacities of the materials were also fairly large. The irreversible Li~+ capacities were fand to be explainable by two factors: the consumption of Li~+ due to the formation of solid electrolyte interface layers within the materials, the amount of which depends on the pore structure of the material, and the trapping of Li~+ by the O included in the material. It was also found that the Si in the materials synthesized using polydiphenylsilane as the Si source could store up to an average of 2.4 Li~+ per atom. These results indicate that by selecting a proper C source for the co-carbonization with polysilane polymers, an anode material for Li~+ batteries with a large reversible capacity and small irreversible capacity can be obtained.