Abstract: A positive electrode material for a nickel metal hydride secondary battery and a method for producing the positive electrode material for a nickel hydrogen secondary battery, capable of improving characteristics of a nickel metal hydride secondary battery by lowering volume resistivity, are provided. The positive electrode material for a nickel metal hydride secondary battery has, in a differential pore distribution in which a pore diameter range is 1.7 nm or more and 300 nm or less, a local maximum value of a highest peak of a differential pore volume positioned in a range of a pore diameter of 1.7 nm or more and 10.0 nm or less.

Abstract: A nickel-containing hydroxide particle covered with cobalt capable of preventing cracks and fissures in the particle and fine powder from being generated due to having an excellent particle strength is provided. The nickel-containing hydroxide particle covered with cobalt, including a covering layer containing cobalt oxyhydroxide formed on a nickel-containing hydroxide particle, wherein an average particle strength is 65.0 MPa or more and 100.0 MPa or less for a particle diameter with a cumulative volume percentage of 50% by volume (D50) of 10.0 ?m or larger and 11.5 ?m or smaller.

Abstract: The nickel-containing hydroxide particle covered with cobalt, wherein in a volume-based particle size distribution, the nickel-containing hydroxide particle covered with cobalt has the maximum peak with a height a, one peak at a height of (½)a or higher, and has a value A of formula (1) calculated from a width b of the maximum peak at a height of (½)a, and in a volume-based particle size distribution after compression treatment, the nickel-containing hydroxide particle covered with cobalt has the maximum peak with a height c, and has a value B of formula (2) calculated from a width d of the maximum peak at a height of (½)c, and wherein the value B and the value A have a relation represented by formula (3): A=[(b×(½)a]/2??(1) B=[(d×(½)c]/2??(2) ?1.50?[(B?A)/A]×1005.

Abstract: The positive electrode active material particle for a secondary battery, containing a metal and/or a metal compound; and a nickel-containing composite compound, wherein a value of X is 0.00 or more and 0.08 or less. X=(C?A)/B ??(I) wherein A means a molar ratio of an amount of the metal in the metal and/or the metal compound to an amount of metals in the nickel-containing composite compound at a secondary particle diameter D90, B means a molar ratio of an amount of the metal in the metal and/or the metal compound to an amount of the metals in the nickel-containing composite compound at a secondary particle diameter D50, and C means a molar ratio of an amount of the metal in the metal and/or the metal compound to an amount of the metals in the nickel-containing composite compound at a secondary particle diameter D10.