LITHIUM ION SECONDARY BATTERY

摘要

A lithium ion secondary battery in which a high capacity, as well as a high level of safety, is achieved, by using an oxide material containing Li and Fe for a negative electrode active material. In the lithium ion secondary battery, the negative electrode active material is a mixed phase of LiFeO2 and LiFe5O8 and a material in which the value calculated as the ratio of the height of a diffraction peak belonging to LiFeO2 (200) plane and the height of a diffraction peak belonging to LiFe5O8 (311) plane, which are obtained by X-ray diffraction method, is 0.18 to 20.4.

主权项

1. A lithium ion secondary battery comprising a positive electrode and a negative electrode facing each other through a separator, which is characterized in that a negative electrode active material is a mixed phase of LiFeO2 and LiFe5O8 obtained by hydrothermal synthesis and comprises a material in which a value calculated as the ratio of the height of a diffraction peak belonging to LiFeO2 (200) plane and the height of a diffraction peak belonging to LiFe5O8 (311) plane, which are obtained by X-ray diffraction method, is 0.18 to 20.4.