POSITIVE ELECTRODE ACTIVE MATERIAL FOR NON-AQUEOUS ELECTROLYTE SECONDARY CELL

摘要

A positive electrode active material for a non-aqueous electrode secondary cell which comprises a composite oxide containing iron and sodium as main components, having a hexagonal crystal structure, and exhibiting a value obtained by dividing the intensity of a peak corresponding to an interplanar spacing of 2.20 Š by the intensity of a peak corresponding to an interplanar spacing of 5.36 Š of 2 or less in the X-ray diffraction analysis of said composite oxide; and a method for preparing the positive electrode active material wherein the above composite oxide is prepared by heating a metal compound mixture mainly containing a sodium compound and an iron compound in the temperature range of 400 to 900‹C, which comprises heating the metal compound mixture in an inert atmosphere in the temperature range of less than 100‹C on the way of the rise in the temperature. The use of the above active material allows the manufacture of a cell which is free from the rapid reduction of the discharge voltage with the progress of discharge. ® KIPO & WIPO 2007