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.sub.xMn.sub.yM.sub.z(OH).sub.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.

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.sub.xMn.sub.yM.sub.z(OH).sub.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.

A nickel composite hydroxide includes nickel, cobalt, manganese, and an element M with an atomic ratio of Ni:Co:Mn:M=1−x1−y1−z1:x1:y1:z1 (wherein M is at least one element selected from a group consisting of a transition metal element other than Ni, Co, Mn, a II group element, and a XIII group element, 0.15≤0.25, 0.15≤y1≤0.25, 0≤z1≤0.1), the nickel composite hydroxide having a cobalt or manganese rich layer from a surface of a particle of the secondary particles toward an inside of the secondary particles and a layered low-density layer between the cobalt or manganese rich layer and a center of the particle of the secondary particles, and a thickness of the cobalt or manganese rich layer and low-density layer is 1% or more and 10% or less to a diameter of the secondary particles.

A nickel composite hydroxide includes nickel, cobalt, manganese, and an element M with an atomic ratio of Ni:Co:Mn:M=1−x1−y1−z1:x1:y1:z1 (wherein M is at least one element selected from a group consisting of a transition metal element other than Ni, Co, Mn, a II group element, and a XIII group element, 0.15≤0.25, 0.15≤y1≤0.25, 0≤z1≤0.1), the nickel composite hydroxide having a cobalt or manganese rich layer from a surface of a particle of the secondary particles toward an inside of the secondary particles and a layered low-density layer between the cobalt or manganese rich layer and a center of the particle of the secondary particles, and a thickness of the cobalt or manganese rich layer and low-density layer is 1% or more and 10% or less to a diameter of the secondary particles.

The present disclosure provides a precursor of a positive electrode active material, capable of obtaining the positive electrode active material that can exhibit a high discharge capacity and high charge/discharge efficiency, by being mounted on a secondary battery using a non-aqueous electrolyte, and the positive electrode active material obtained from the precursor, as well as a method for producing the positive electrode active material.

The nickel composite hydroxide particles that are precursors of a positive electrode active material of a non-aqueous electrolyte secondary battery, having a void ratio of 45.0% or more and 55.0% or less.

The present disclosure provides a precursor of a positive electrode active material, capable of obtaining the positive electrode active material that can exhibit a high discharge capacity and high charge/discharge efficiency, by being mounted on a secondary battery using a non-aqueous electrolyte, and the positive electrode active material obtained from the precursor, as well as a method for producing the positive electrode active material.

The nickel composite hydroxide particles that are precursors of a positive electrode active material of a non-aqueous electrolyte secondary battery, having a void ratio of 45.0% or more and 55.0% or less.

The nickel composite hydroxide that is a precursor of a positive electrode active material of a non-aqueous electrolyte secondary battery, comprising Ni, Co, and one or more additive metal elements M selected from the group consisting of Mn, Al, Fe, and Ti, wherein when a peak intensity of a diffraction peak appearing in a range of 2θ=8.0±2.0° in powder X-ray diffraction measurement using CuKα rays is defined as α, and a peak intensity of a diffraction peak appearing in a range of 2θ=19.0±2.0° in powder X-ray diffraction measurement using CuKα rays is defined as β, of the nickel composite hydroxide having a secondary particle diameter having a cumulative volume percentage of 90% by volume (D90) or more, a value of β/α is 13.0 or less.

The nickel composite hydroxide that is a precursor of a positive electrode active material of a non-aqueous electrolyte secondary battery, comprising Ni, Co, and one or more additive metal elements M selected from the group consisting of Mn, Al, Fe, and Ti, wherein when a peak intensity of a diffraction peak appearing in a range of 2θ=8.0±2.0° in powder X-ray diffraction measurement using CuKα rays is defined as α, and a peak intensity of a diffraction peak appearing in a range of 2θ=19.0±2.0° in powder X-ray diffraction measurement using CuKα rays is defined as β, of the nickel composite hydroxide having a secondary particle diameter having a cumulative volume percentage of 90% by volume (D90) or more, a value of β/α is 13.0 or less.

The present invention relates to a positive electrode active material comprising a secondary particle formed of agglomerates of a plurality of primary particles, wherein each primary particle comprises a first primary particle constituting a core portion of the secondary particle, and a second primary particle provided so as to surround the first primary particle and constituting a shell portion of the secondary particle. In particular, the first primary particle consists of a1 and a2, wherein the a1 is the average length of the major axis of the first primary particle, and the a2 is the average length of the minor axis perpendicular to the a1, wherein the a1 is equal to or greater than the a2. In addition, the second primary particle consists of b1 and b2, wherein the b1 is an average length of the major axis of the second primary particle, and b2 is an average length of the minor axis perpendicular to the b1, wherein the b1 is greater than b2, and the ratio (b1/b2) of the b1 to b2 is 1 to 25.

The present invention relates to a cathode additive, a method for preparing the same, and a cathode and a lithium secondary battery including the same. More specifically, one embodiment of the present invention provides a cathode additive that can offset an irreversible capacity imbalance, increase the initial charge capacity of a cathode, and simultaneously inhibit the generation of gas in a battery.