Nickel manganese composite hydroxide and method for producing same, positive electrode active material for nonaqueous electrolyte secondary battery and method for producing same, and nonaqueous electrolyte secondary battery
Provided are a nickel-manganese composite hydroxide capable of producing a secondary battery having a high particle fillability and excellent battery characteristics when used as a precursor of a positive electrode active material and a method for producing the same. A nickel-manganese composite hydroxide is represented by General Formula: Ni x Mn y M z (OH) 2+α and contains a secondary particle formed of a plurality of flocculated primary particles. The primary particles have an aspect ratio of at least 3, and at least some of the primary particles are disposed radially from a central part of the secondary particle toward an outer circumference thereof. The secondary particle has a ratio I(101)/I(001) of a diffraction peak intensity I(101) of a 101 plane to a peak intensity I(001) of a 001 plane, measured by an X-ray diffraction measurement, of up to 0.15.
1. A positive electrode active material for a nonaqueous electrolyte secondary battery, the positive electrode active material comprising:
a lithium-nickel-manganese composite oxide containing a secondary particle formed of a plurality of flocculated primary particles and represented by General Formula (2):
Li 1+u Ni x Mn y M z O 2+β (in Formula (2), M is at least one additional element selected from Co, Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, Fe, and W; and u, x, y, z, and β satisfy −0.05≤u≤0.5, 0.1≤x≤0.8, 0.1≤y≤0.6, 0≤z≤0.8, x+y+z=1.0, and 0≤β≤0.5), wherein
when an arbitrary radial direction from a center of a cross section of the secondary particle toward an outside thereof is regarded as an x-axis direction and a direction perpendicular to the x-axis direction is regarded as a y-axis direction, an orientation rate of a crystal ab plane measured by an electron backscatter diffraction method is at least 55% in each of the x-axis direction and the y-axis direction.
2. A positive electrode active material for a nonaqueous electrolyte secondary battery, the positive electrode active material comprising:
a lithium-nickel-manganese composite oxide containing a secondary particle formed of a plurality of flocculated primary particles and represented by General Formula (2):
Li 1+u Ni x Mn y M z O 2+β (in Formula (2), M is at least one additional element selected from Co, Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, Fe, and W; and u, x, y, z, and β satisfy −0.05≤u≤0.5, 0.1≤x≤0.8, 0.1≤y≤0.6, 0≤z≤0.8, x+y+z=1.0, and 0≤β≤0.5), wherein
the primary particles have an aspect ratio of at least 2, and at least some of the primary particles are disposed radially in a direction from a central part of the particle to an outer circumference thereof, a sparse density obtained from an image analysis result of a SEM image of a cross section of the secondary particle is at least 0.5% and up to 25%, and a particle strength is at least 70 MPa and up to 100 MPa, and
a volume-average particle diameter MV is at least 5 μm and up to 20 μm, and [(D90-D10)/average particle diameter] that is an indicator to represent a spread of particle size distribution is at least 0.7.
3. The positive electrode active material for a nonaqueous electrolyte secondary battery according to claim 2 , wherein in an area within 50% of a radius of the secondary particle from the outer circumference of the secondary particle toward the central part thereof, at least 50% of the primary particles in number relative to a total number of the primary particles present within this area are disposed radially.
4. The positive electrode active material for a nonaqueous electrolyte secondary battery according to claim 1 , wherein a volume-average particle diameter MV is at least 5 μm and up to 20 μm, and [(D90-D10)/average particle diameter] that is an indicator to represent a spread of particle size distribution is at least 0.7.
5. A nonaqueous electrolyte secondary battery comprising:
a positive electrode that comprises the positive electrode active material for a nonaqueous electrolyte secondary battery according to claim 1 .
6. A nonaqueous electrolyte secondary battery comprising:
a positive electrode that comprises the positive electrode active material for a nonaqueous electrolyte secondary battery according to 11.