热处理对三聚磷腈复合硫正极材料性能的影响

Effects of Heat Treatment on Properties of Triphosphazene- sulfur Composites as Cathode

通过亲核取代方法合成了一种新型三聚磷腈复合硫正极材料TPS,并对其进行了热处理。TPS是环部分破裂的硫化三聚磷腈和单质硫的混合物,磷腈基团将表面修饰呈棱角形貌;热处理后氮磷链断裂,主体结构为硫,在Li CF3SO3/DME+DGM电解液50u A电流下首次放电比容量为1058.7m Ah/g,高于热处理前的627.4m Ah/g。热处理后硫引起的"飞梭效应"较严重,前15次循环比容量都高于TPS,从第5次开始,容量保持率要低于TPS。30次循环后比容量为102m Ah/g,小于TPS的197.44m Ah/g。

A novel sulfur- containing triphosphazenes （TPS） was synthesized with the method of nucleophilic substitution, and then TPS was treated by heating. TPS was a mixture of partly rupture ring of triphosphazenes sulfide and sulfur, and phosphazene groups played a modified role on the surface of sulfur with angular morphology. After heat treatment, bond of nitrogen-phosphorus broke, the main structure was the same as elemental sulfur. In the 1M LiCF3SO3/DME ＋ DGM electrolyte, the first discharge capacity was 1058.7mAh/g at the current of 50uA, higher than 627.4mAh/g of TPS. Compared to TPS, after heat treatment, ＂shuttle effect＂ caused by sulfur was more serious. The specific capacity of the first 15 cycles was higher than TPS, from the 5th cycle, the capacity retention rate was lower than TPS, in the 30th cycle, capacity was 102mAh./g, lower than 197.44mAh/g of TPS.