The Study on the Amorphous Oxides as Cathodes for Lithium Secondary Battery

点击翻译按钮获取中文摘要

From the aspects of developing the practical lithium secondary battery, the various cathode, anode and electrolyte materials were investigated. As a theme for each subject, we selected (1) the study on the amorphous oxides based on Cr_3O_8 and V_2O_5, (2) developing the salty electrolyte salt substituted for LiClO_4, and (3) the study on the lithium-carbon composite electrode as anode for lithium secondary battery, respectively. The results for these studies during the term of this project were mentioned below.(1) The amorphous Cr_3O_8 prepared from crystal Cr_3O_8 showed the superior characteristics. It has high energy density, high power density and good cyclability. It is discharged homogeneously because of its amorphous structure, of which the potential energy is flattened and the discharge proceeds very smoothly. One of the problems of this compound was the difficulties of making fine of each Cr_3O_8 particle. This results in the worse charge-discharge characteristics at the high … More rate discharging. The brannerite type compound CuV_<2-x>Mo_xO_6 also showed the good cyclability. In addition, there is the interesting feature that the intercalation and deintercalation of lithium and copper occurred in alternate directions at the same time. And the vanadium rich composition compared with the molybdenum rich one has the amorphous structure and shows the good charge-discharge characteristics. (2) In respect of current density and cyclability, the LiPF_6 in PC : DME (1 : 1) electrolyte had the best properties among all electrolytes. (3) It was shown that lithium-carbon composite electrode restrained the formation of lithium dendrites on the lithium substrate. The reaction between lithium and carbon depends on the structure of carbon which means the crystallinity, orientation etc. The higher crystallinity showed the larger amount of lithium accommodation. It is proved that the orientation of carbon crystal has a large effect on the rate of lithium intercalation. From these knowledge, the most suitable structure as the anode of lithium secondary battery was proposed. Less