Synthesis of co-oligomers containing 1,1-Dialkyl-3,4-diphenyl-2,5-silolene and aromatic diolene and analysis of their anodic properties for lithium-ion battery

Abstract

The co-oligomerization of 1,1-dialkyl-2,5-dibromo-3,4-diphenyl-siloles Ia,b with aromatic diols IIa′∼ c′ in the presence of K2CO3 and N-methyl-2-pyrrolidone/toluene as cosolvents by nucleophilic aromatic substitution yielded oligomers containing 1,1-dialkyl-3,4-diphenyl-2,5-silolene and aromatic diolene such as IIIaa′∼bc′ as brownish solids. The oligomeric materials IIIaa′∼bc′ were characterized using spectroscopic methods, such as 1H, 13C NMR, FT-IR, photoelectronic properties, and thermal stabilities. Typically, oligomers IIIac′ and IIIbc′ show good anodic properties for lithium-ion batteries, such as rate capabilities of 720 and 490 mAh/g at 0.5 A/g after the 35th cycle, charge capacities of 740 mAh/g at the 150th cycle and 500 mAh/g at the 200th cycle, and long-cycle performances of 820 mAh/g after the 157th cycle and 530 mAh/g after the 180th cycle, respectively. The anodic property of the cell fabricated with the oligomer IIIac′ Li cell was generally superior to that of the cell made with oligomer IIIbc′ and was also much higher than that of graphite. Both IIIac′ and IIIbc′ may be applicable as anodic materials in lithium-ion secondary batteries.