Investigation of graphite intercalation compounds of some transition metal chlorides as the cathodematerials for lithium rechargeable battery

某些过渡金属氯化物的石墨嵌入化合物具有刚性的层状结构和较高的电子导电性。本文研究了将锂电化学插入过渡金属氯化物的GICs中，从而将GICs应用于锂二次电池正极材料。研究了C_<20>TaCl_5五氯化钽一级GIC在1 M LiClO_4/碳酸丙烯酯电解质中的电化学锂化行为。在放电开始时，证实了从一级到更高一级的退化，表明钽种从宿主材料中脱插发生了。在主材料或电解质中的五价钽被认为被还原到较低的氧化态。另一方面，指控是不可能的。结果表明，氯化钽不适合作为锂二次电池的正极材料。然而，有人认为锂可以插入到含有各种价态过渡金属的高阶gic中，而不会破坏层状结构。

Graphite intercalation compounds (GIC) of some transition metal chlorides have rigid layered structures and high electronic conductivity. In this study, electrochemical insertion of lithium into the GICs of some transition metal chlorides was investigated in order to apply the GICs to the cathode materials for lithium secondary batteries.The electrochemical lithiation behavior of a 1 st stage GIC of tantalum pentachloride, C_<20>TaCl_5, was investigated in 1 M LiClO_4/propylene carbonate electrolyte. The degradation of the stage number from 1 st to higher stages was confirmed at the beginning of the discharge, indicating that the deintercalation of tantalum species from the host material occurred. The pentavalent tantalum species, which is in the host material or in the electrolyte, were considered to be reduced to the lower oxidation states. On the other hand, the charge was impossible.These results showed that the GICs of tantalum chloride are not suit able for cathode materials for lithium secondary batteries. However, it was suggested that lithium can be inserted into the higher stage GICs containing the transition metals which can take various valence states without destruction of the layered structures.