Structure and physical property of Lithium intercalation materials

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We focused basic aspect of electrode materials for lithium-ion battery. To improve the characteristics and to design new lithium battery systems, we clarified the structure-property relationships for the following subjects.The transition metal oxide LiMO_2 (M-Ni, Co, Ni_<l-y>Co_y) with the layered rock salt structure has been studied as insertion electrode in rechargeable lithium ion battery. It is known that the disorder of lithium and transition metal sites produced in the sintering process affects the magnetic and electrochemical properties. In this study, we have investigated the relationships between the disorder and magnetic and electrochemical property using neutron diffraction and SQUID measurement.Li_<l-∂>(Ni_<l-y>Co_y)_<1+∂>O_2 samples(∂: extent of disorder) indicated spin-glass like behavior. The spin-glass transition temperature (Tg) shifted higher with the increase in ∂. The discharge capacity also increased with the decrease in ∂. These results indicate that the disorder … More in LiMO_2 is correlated with the magnetic and electrochemical property.In order to design the ideal interface of the lithium battery electrode, we attempted making single crystal thin film of LiNiO_2 and LiCoO_2 using the pulse laser deposition method. The epitaxial thin films of LiCoO_2 and LiNiO_2 were obtained, those orientation was controlled by the substrate orientation.The deterioration of lithium manganese oxide spinet (LiMn_2O_4) during charge-discharge cycle at high temperature is a serious defect for the practical use as a lithium battery electrode. Neutron diffraction measurement of lithium manganese oxide spinet powders synthesized under various conditions was carried out before and after the high temperature storage and the. structures were refined. These results suggest dissolution of manganese ion proceeds at bulk structure as well the surface of the material. The decrease in occupancy of oxygen also supports the conclusion that the bulk structure of LiMn_2O_4 is broken by high temperature storage. Less