Provided are a nickel-based active material for a lithium secondary battery, a method of preparing the nickel-based active material, and a lithium secondary battery including a positive electrode including the nickel-based active material. The nickel-based active material includes at least one secondary particle that includes at least two primary particle structures, the primary particle structures each including a porous inner portion and an outer portion having a radially arranged structure, and the secondary particle including at least two radial centers.

Spherical silica and/or silicate particles having a d50 median particle size from 1 to 5 μm, a d95 particle size less than 8 μm, an oil absorption from 40 to 100 cc/100 g, a pack density from 20 to 60 lb/ft.sup.3, and a sphericity factor (S.sub.80) of at least 0.9, are disclosed, as well as methods for making these spherical particles, and dentifrice compositions containing the spherical particles.

A perovskite-type composite oxide powder is a perovskite-type composite oxide powder represented by a general formula ABO.sub.3-δ (where δ represents an amount of deficiency of oxygen and 0≤δ<1), an element contained in an A site is La, elements contained in a B site are Co and Ni and a crystallite size determined by a Williamson-Hall method is equal to or greater than 20 nm and equal to or less than 100 nm. In this way, when the perovskite-type composite oxide powder is used as an air electrode material for a fuel cell, an air electrode in which the resistance thereof is low and the conductivity thereof is high can be obtained.

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.

A film-forming powder containing a rare earth oxyfluoride has an average particle size D50 of 0.6-15 μm, a total volume of ≤10 μm pores of 0.51-1.5 cm.sup.3/g as measured by mercury porosimetry, and a BET surface area of 3-50 m.sup.2/g is suitable for forming a dense film in high yields or deposition rates and high productivity. The film-forming powder having a greater pore volume can be prepared by forming a rare earth ammonium fluoride complex salt on surfaces of rare earth oxide particles to provide precursor particles, and heat treating the precursor particles at a temperature of 350 to 700° C.

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 present invention relates to a positive electrode active material which has the structural stability of a lithium composite oxide constituting a positive electrode active material and a lithium secondary battery including the same. The lithium composite oxide constituting the positive electrode active material according to the present invention is able to reduce the surface area and grain boundary of secondary particles having a side reaction with an electrolyte solution, thereby improving high-temperature stability and reducing gas generation caused by the positive electrode active material, and the structural stability of the lithium composite oxide may be improved using a cation-mixing layer covering the surface of a primary particle.

A positive electrode active material has a small difference in a crystal structure between the charged state and the discharged state. For example, the crystal structure and volume of the positive electrode active material, which has a layered rock-salt crystal structure in the discharged state and a pseudo-spinel crystal structure in the charged state at a high voltage of approximately 4.6 V, are less likely to be changed by charging and discharging as compared with those of a known positive electrode active material. In order to form the positive electrode active material having the pseudo-spinel crystal structure in the charged state, it is preferable that a halogen source such as a fluorine and a magnesium source be mixed with particles of a composite oxide containing lithium, a transition metal, and oxygen, which is synthesized in advance, and then the mixture be heated at an appropriate temperature for an appropriate time.

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.