Provided is a positive electrode active material for a non-aqueous electrolyte secondary battery. Also provided is a method for producing a positive electrode active material for a non-aqueous electrolyte secondary battery, comprising: providing a lithium transition metal composite oxide having a ratio D.sub.50/D.sub.SEM of 1 or more and 4 or less, having a layered structure, and having a ratio of a number of moles of nickel to a total number of moles of metals other than lithium of 0.3 or more and less than 1, and a ratio of a number of moles of cobalt to the total number of moles of metals other than lithium of 0 or more and less than 0.5; bringing the lithium transition metal composite oxide into contact with a cobalt compound to obtain an adhered material; and heat-treating the adhered material at a temperature higher than 700° C. and lower than 1100° C.

Process for precipitating a mixed carbonate or mixed (oxy)hydroxide comprising nickel from an aqueous solution comprising a nickel salt, wherein such process is carried out in a vessel comprising (A) a vessel body, (B) one or more elements selected from draft tubes and guide vanes, (C) at least one stirrer whose pressure zone is in or between element(s) (B), and wherein the process comprises the step of simultaneously adding said solution comprising a nickel salt in or between element(s) (B) and a solution of alkali metal carbonate or hydroxide in or between or outside element(s) (B).

A positive electrode active material powder for a lithium secondary battery, which includes a lithium composite transition metal oxide in the form of a single particle consisting of one nodule, or a pseudo-single crystal, which is a composite of 30 or less nodules, where the positive electrode active material powder satisfies Expression 1: 0.5≤D.sub.mean33 d.sub.press/D.sub.50≤3.Where D.sub.mean is an average particle diameter of the nodules as measured using an electron backscatter diffraction (EBSD) pattern analyzer, d.sub.press is a press density measured after 5 g of the positive electrode active material powder is input into a circular mold with a diameter of 2 cm and pressurized at a pressure of 2000 kgf, and D.sub.50 is a value corresponding to a cumulative volume of 50% in the particle size distribution of the positive electrode active material powder.

A positive electrode active material for a lithium secondary battery comprising a compound represented by Chemical Formula 1 is introduced.

Li.sub.1+mNi.sub.1-w-x-y-zCo.sub.wMn.sub.xM1.sub.yM2.sub.zO.sub.2-pX.sub.p  [Chemical Formula 1] (In the Chemical Formula 1, M1 and M2 are different from each other, and any one element selected from the group consisting of Al, Mg, Zr, Sn, Ca, Ge, Ti, Cr, Fe, Zn, Y, Ba, La, Ce, Sm, Gd, Yb, Sr, Cu and Ga respectively, X is any one element selected from the group consisting of F, N, S, and P, w, x, y, z, p and m are respectively 0.125<w<0.202, 0.153<x<0.225, 0≤y≤0.1, 0≤z≤0.1, 0.34≤w+x≤0.36, 0≤p≤0.1, and −0.1≤m≤0.2.)

A positive-electrode active material precursor for a nonaqueous electrolyte secondary battery is provided that includes a nickel-cobalt-manganese carbonate composite represented by general formula Ni.sub.xCo.sub.yMn.sub.zM.sub.tCO.sub.3 (where x+y+z+t=1, 0.05≤x≤0.3, 0.1≤y≤0.4, 0.55≤z≤0.8, 0≤t≤0.1, and M denotes at least one additional element selected from a group consisting of Mg, Ca, Al, Ti, V, Cr, Zr, Nb, Mo, and W) and a hydrogen-containing functional group, wherein H/Me representing the ratio of the amount of hydrogen to the amount of metal components Me included in the positive-electrode active material precursor is greater than or equal to 1.60.

A positive electrode active material precursor has a hydroxide represented by Formula 1, wherein the positive electrode active material precursor is a secondary particle, in which a plurality of primary particles are aggregated, and includes crystallines in which major axes of the primary particles are arranged in a direction from a center of the secondary particle toward a surface thereof and a (001) plane of the primary particle is arranged parallel to the major axis of the primary particle. A method of preparing the positive electrode active material precursor, and a positive electrode active material prepared by using the positive electrode active material precursor are also provided.

A method for preparing ternary positive material in a lithium battery includes mixing nickel salt, cobalt salt, and manganese salt to form a mixed solution. A precipitant and a complexing agent are added into the mixed solution, thereby adjusting a pH value to a range of 10.5 to 12 and obtaining a precursor A. The precursor A and lithium salt are ground by a ball mill to obtain a precursor B, precursor B then being sintered in an air or oxygen atmosphere. The sintering includes heating at a first heating speed of 5 to 15° C./min to a first temperature of 400 to 800° C. and being held at such temperature for 1 to 6 h, and heating at a second heating speed of 1 to 10° C./min to a second temperature of 900 to 980° C. and being held there for 8 to 10 h.

A method of preparing a bimodal positive electrode active material precursor and a positive electrode active material prepared from the same are disclosed herein. In some embodiments, the method includes inputting a first reaction source material including a first aqueous transition metal solution into a reactor, precipitating at pH 12 or more to induce nucleation of a first positive electrode active material precursor particle, and at less than pH 12 to induce growth of the same, inputting a second reaction source material including a second aqueous transition metal solution into the reactor containing the first positive electrode active material precursor particle, precipitating at pH 12 or more to induce the nucleation of a second positive electrode active material precursor particle, and at less than pH 12 to induce simultaneous growth of the first and second positive electrode active material precursor particles, thereby preparing a bimodal positive electrode active material precursor.

A positive electrode active material and a method for producing the same are disclosed herein. In some embodiments, a positive electrode active material includes a lithium-nickel-based oxide in the form of at least one of single particles or a pseudo-single particles, wherein each single particle consists of one nodule, wherein each pseudo-primary particles is a composite of 30 or fewer nodules, wherein on the surface of the lithium-nickel-based oxide, a number of nickel ions having an oxidation number of +3 or higher is greater than a number of nickel ions having an oxidation number less than +3.

The present invention provides a composite oxide that can achieve a high low-temperature output characteristic, a method for manufacturing the same, and a positive electrode active material in which the generation of soluble lithium is suppressed and a problem of gelation is not caused during the paste preparation. A positive electrode active material for non-aqueous electrolyte secondary batteries, including a lithium-metal composite oxide powder including a secondary particle configured by aggregating primary particles containing lithium, nickel, manganese, and cobalt, or a lithium-metal composite oxide powder including both the primary particles and the secondary particle. The secondary particle has a porous structure inside as a main inside structure, the slurry pH is 11.5 or less, the soluble lithium content rate is 0.5[% by mass] or less, the specific surface area is 3.0 to 4.0 [m.sup.2/g], and the porosity is more than 50 to 80[%].