Preparation of Dendrimer-Sulfur Composites and their Application to Positive Active Material for Lithium Secondary Battery

更高功率和更薄的二次电池将减轻便携式电气设备的重量，例如蜂窝电话和便携式计算机。具有可聚合硫基团的有机硫化合物，例如2，5-二巯基-1，3，4-噻二唑（DMcT），是用于高能量存储二次电池的正极活性材料的最有希望的候选者之一。我们制备了新型二硫键聚合物，其具有超支化骨架和每个分支末端的环状二硫键结构。研究了它们在有机电解液中的电化学行为及作为正极活性物质的可能性。以支化聚酯和含环状二硫键的硫辛酸为原料，合成了具有环状二硫键结构的支化聚酯。通过FTIR、NMR和MALDI-TOFF MASS谱对聚合物的结构进行了表征。超支化聚合物在有机电解质溶液（如碳酸丙烯酯、1，2-二甲氧基乙烷和LiClO_4的电解质溶液）中的电极表现出基于环状二硫化物的电化学响应。超支化聚合物的氧化还原电位和二硫键的行为取决于其支化结构。具有基于该化合物的正电极的测试电池的容量为27.9 - 54.8Ah/kg<-1>。

A higher-power and thinner secondary battery will reduce the weight of potable electrical equipment, such as a cellular telephone and portable computer. Organosulfur compounds, such as 2, 5-dimercapto-1, 3, 4-thiadiazole (DMcT), which have polymerizable sulfur groups, are one of the most promising candidates of positive active materials for a high-energy storage secondary battery. We prepared new-type disulfide polymers that have a hyperbranch backbone and cyclic disulfide structures at the terminal of each branches. Their electrochemical behavior in an organic electrolyte and possibility as positive active material were investigated. Branched polyesters with cyclic disulfide structure were prepared from branched polyester and lipoic acid which has cyclic disulfide moiety. The structure of the polymers was identified from the results of FTIR, NMR, and MALDI-TOFF MASS spectroscopy. The electrodes with the hyperbranch polymers in the organic electrolyte solution (for example, the electrolyte solution form propylene carbonate, 1, 2-dimethoxyethane, and LiClO_4) showed electrochemical responses based on the cyclic disulfide. The redox potential and behavior of the disulfide bonds in the hyperbranch polymer depended on its branched structure. The capacity of the test cell with the positive electrode based on the compound was 27.9 - 54.8 Ah kg^<-1>.