To provide a positive electrode material excellent in cycle characteristic and high-load characteristic by using the spinel LiMn2O4, specified by the specific surface area, the ratio of the crystallization parameter of the X-ray diffraction pattern and the solid NMR spectrum using lithium nuclei, as the positive electrode active material.
The spinel LiMn2O4 used as a positive electrode material has the specific surface area of 0.5-1.9 m2/g, the crystallization parameters α for diffractions (311), (222), (400), (440) has a values in the range of 1.1-2.3 when the ratio of the half width to the peak intensity of the diffraction peak (111) of the power X-ray diffraction pattern, has the area ratio of 30-50% of the spectrum B against the spectrum A within the spectrum constituted of the broad spectrum A having the line width exceeding 1000 ppm and the spinning side band spectrum B of at least below 1000 ppm in the solid NMR spectrum using lithium nuclei, and mainly belongs to the space group Fd3m (No.227).
NAGAYAMA MASATOSHI
NAKAJIMA TAKUYA
HASHIMOTO AKIRA
ARIMOTO SHINJI
