| 摘要 |
PROBLEM TO BE SOLVED: To enhance energy density of a positive electrode active material composed of a metal oxide containing Ni as the principal metal element, and to provide manufacture thereof. SOLUTION: This active material is a metal oxide having Ni as the principal metal element, containing at least Mn in a solid solution or an eutectic state, an average valence of Mn being 3.3 or more, and a half value width of a peak around 2θ=37 to 40 deg. of X ray diffraction using the CuKα line is 1.2 degrees or less and/or a ratio of B/A is 1.25 or less, where A denotes an integrated intensity of a peak located around 2θ=37 to 40 deg. and B denotes that of a peak located around 2θ=18 to 21 deg., and/or a spatial volume containing fine pores having a radius not more than 40 Åoccupies 60% or more of the total spatial volume of fine pores. This oxide is obtained by growing the metal oxide while keeping dissolved oxygen in an aqueous solution within a reaction vessel at 5 mg/l or less and subsequently oxidizing it. |
