The positive electrode active material with lithium composite oxide A containing W and Ni and W-free lithium composite oxide B containing Ni. Regarding the lithium composite oxide A, the proportion of Ni relative to the total moles of metal elements except for lithium is 30 to 60 mol %, 50% particle size D50 is 2 to 6 μm, 10% particle size D10 is 1.0 μm or more, and 90% particle size D90 is 6.8 μm or less. Regarding the lithium composite oxide B, the proportion of Ni relative to the total moles of metal elements except for lithium is 50 to 95 mol %, 50% particle size D50 is 10 to 22 μm, 10% particle size D10 is 7.0 μm or more, and 90% particle size D90 is 22.5 μm or less. The mass ratio of the lithium composite oxide B to the lithium composite oxide A is 1:1 to 5.7:1.

This application provides a lithium-nickel-manganese-based composite oxide material, where a K value of the lithium-nickel-manganese-based composite oxide material ranges from 1 to 2, and the K value is calculated based on the following formula: K=D.sub.v50/d.sub.v50, where d.sub.v50 is a volume median crystallite diameter of crystal particles of the lithium-nickel-manganese-based composite oxide material; and D.sub.v50 is a volume median particle diameter of the lithium-nickel-manganese-based composite oxide material.

This application provides a lithium-nickel-manganese-based composite oxide material, where a K value of the lithium-nickel-manganese-based composite oxide material ranges from 1 to 2, and the K value is calculated based on the following formula: K=D.sub.v50/d.sub.v50, where d.sub.v50 is a volume median crystallite diameter of crystal particles of the lithium-nickel-manganese-based composite oxide material; and D.sub.v50 is a volume median particle diameter of the lithium-nickel-manganese-based composite oxide material.

The present disclosure relates to a positive electrode active material, a preparing method therefor, and a lithium secondary battery including same. A positive electrode active material according to an embodiment comprises: a core including a lithium nickel composite oxide represented by Chemical Formula 1; and a surface layer present on the core and including at least one of a water-soluble ammonium-based organic compound and a water-soluble amine-based organic compound. The details of Chemical Formula 1 are as defined in the specification.

The cathode active material is capable of reducing cathode resistance of a secondary battery by enhancing electron conductivity thereof without reducing discharge capacity of the secondary battery. The method for manufacturing a cathode active material includes: mixing transition metal-containing composite compound particles containing lanthanum with a lithium compound to obtain a lithium mixture; calcinating the lithium mixture at a temperature equal to or lower than the melting point of the lithium compound; and then subjecting the lithium mixture to main firing at a firing temperature within a range of 725° C. to 1000° C. Lithium carbonate is preferably used as the lithium compound, and in this case, the calcination temperature is within a range of 600° C. to 723° C. It is preferable to obtain the transition metal-containing composite compound particles containing lanthanum by a coprecipitation method and to uniformly disperse a lanthanum element in the particles.

Provided are a battery-level Ni—Co—Mn mixed solution and a preparation method for a battery-level Mn solution, the steps thereof comprising: acid dissolution (S1), alkalization to remove impurities (S2), synchronous precipitation of calcium, magnesium, and lithium (S3), deep ageing to remove impurities (S4), synergistic extraction (S5), and refining extraction (S6). The steps of deep ageing to remove impurities (S4) and synergistic extraction (S5) comprise: performing deep ageing on a filtrate obtained from the step of synchronous precipitation of calcium, magnesium, and lithium (S3), and after performing filtration to remove impurities, obtaining an aged filtrate; using P204 to extract the aged filtrate and obtain a loaded organic phase, and subjecting the loaded organic phase to staged back-extraction to obtain the battery-level Ni—Co—Mn mixed solution and a Mn-containing solution. By means of the cooperation between the multiple process steps of synchronous precipitation of calcium, magnesium, and lithium (S3), deep ageing to remove impurities (S4), and synergistic extraction (S5), the impurity content of the obtained battery-level Ni—Co—Mn mixed solution is significantly lowered, and the battery-level Ni—Co—Mn mixed solution can be directly used to prepare a lithium battery ternary precursor material. At the same time, the battery-level Mn solution can also be obtained, which is favorable for large-scale applications of the process and increasing economic benefits.

The present disclosure 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 disclosure 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 a gas in a battery.

Electrode active material comprising (A) a core material according to general formula Li.sub.1+x1TM.sub.1−x1O.sub.2 wherein TM is a combination of Ni and at least one of Mn, Co and Al, and, optionally, at least one more metal selected from Mg, Ti, Zr, Nb, Ta, and W, and x1 is in the range of from −0.05 to 0.2, and (B) particles of cobalt compound(s) and of aluminum compound(s) and of titanium compound(s) or zirconium compound(s) wherein the molar ratio of lithium to cobalt in said particles is in the range of from zero to below 1 and wherein said particles are attached to the surface of the core material.

The present disclosure relates to a positive active material, a method of preparing the same, and a lithium secondary battery having a positive electrode including the positive active material, the positive active material including: a lithium transition metal oxide having a portion of Li substituted by Na, and including Ni and Co; and a cobalt-containing coating layer arranged on the surface of the lithium transition metal oxide particle, wherein the lithium transition metal oxide particle includes a concentration gradient region in which the concentration of Co decreases in a direction from the surface to the center of the particle.

The present disclosure relates to a positive electrode active material, a method of preparing the same, and a lithium secondary battery having a positive electrode including the same. The positive electrode active material includes: a lithium transition metal oxide particle in which a portion of Li is substituted with Na, and which includes Ni and Co atoms, wherein the lithium transition metal oxide particle includes a concentration gradient region in which the concentration of Co atoms decreases from the surface toward the center of the particle.