An advantage is to provide a non-aqueous electrolyte secondary battery with improved heat resistance. A positive electrode active material contains a lithium-transition metal composite oxide containing 80 mol % or more of Ni and 0.1 mol % to 1.5 mol % of B on the basis of the total number of moles of metal elements excluding Li, and B and at least one element (M1) selected from Groups 4 to 6 are present on at least the surfaces of particles of the composite oxide. When particles having a volume-based particle size larger than 70% particle size (D70) are first particles, and particles having a volume-based particle size smaller than 30% particle size (D30) are second particles, the molar fraction of M1 on the basis of the total number of moles of metallic elements excluding Li on the surfaces of the second particles is greater than that of the first particles.

A process for producing a surface-modified particulate lithium nickel metal oxide material is provided. The process comprises the addition of a controlled quantity of a coating liquid to lithium nickel metal oxide particles followed by a calcination step.

A positive electrode active material for a non-aqueous electrolyte secondary battery, according to an example of this embodiment, includes a lithium transition metal composite oxide which has a layered structure and contains at least Ni, Al, and Ca. The lithium transition metal composite oxide has a Ni content of 85-95 mol %, an Al content of at most 8 mol %, and a Ca content of at most 2 mol % with respect to the total amount of metal elements other than Li. In addition, the proportion of metal elements other than Li present in a Li layer is 0.6-2.0 mol % with respect to the total amount of metal elements other than Li contained in the composite oxide.

A positive active material includes a nickel-based composite metal oxide having the form of secondary particles in which a plurality of primary particles are agglomerated, where each secondary particle includes a core and a shell, the primary particles of the shell are coated with a manganese-containing nickel-based composite metal oxide, and the manganese-containing nickel-based composite metal oxide has a layered structure.

Provided is a positive electrode active material for a non-aqueous electrolyte secondary battery, the active material including a lithium-transition metal composite oxide containing lithium, nickel, cobalt, and manganese, having a layered structure, having a ratio D.sub.50/D.sub.SEM of from 1 to 4, and having a ratio of a number of moles of nickel to a total number of moles of metals other than lithium of greater than 0.8 and less than 1, a ratio of a number of moles of cobalt to the total number of moles of metals other than lithium of less than 0.2, a ratio of a number of moles of manganese to the total number of moles of metals other than lithium of less than 0.2, and a ratio of the number of moles of manganese to a sum of the number of moles of cobalt and the number of moles of manganese of less than 0.58.

A positive-electrode active material for a lithium-ion secondary battery, wherein an average pore size of the positive-electrode active material is 0.2 μm to 1.0 μm when a pore size is measured in a range of 0.0036 μm to 400 μm.

The present invention relates to a lithium metal complex oxide and a preparation method thereof, and more particularly, to a lithium metal complex oxide mixed with a metal compound for a lithium reaction, stirred and heat-treated to allow residual lithium and a metal compound for reducing lithium (or a metal compound for lithium reduction) to react with each other on a surface to form a product, which is included in the lithium metal complex oxide, in which the content of Ni.sup.3+ is higher than the content of Ni.sup.2+ and a ratio of Ni.sup.3+/Ni.sup.2+ is 1.5 or greater so that life characteristics and capacity characteristics are improved, while residual lithium is reduced, and a preparation method thereof.

A cathode active material precursor for a lithium metal oxide is provided. The cathode active material precursor comprises a metal-containing oxyhydroxide. The metal-containing oxyhydroxide comprises nickel and an additional metal. At least 50 mol. % of the nickel of the metal-containing oxyhydroxide has an oxidation state of +3. A method of forming a cathode active material precursor is also provided. The method comprises combining a nickel-containing compound, an additional metal-containing compound, an oxidizing agent, and a solvent to form a solution. The method further comprises exposing the solution to heat at a temperature of from about 30° C. to about 90° C. to form a precipitate comprising the metal-containing oxyhydroxide.

Process for making a partially coated electrode active material wherein said process comprises the following steps: (a) Providing an electrode active material according to general formula Li.sub.1+xTM.sub.1-xO.sub.2, wherein TM is Ni and, optionally, at least one of Co and Mn, and, optionally, at least one element selected from Al, Mg, and Ba, transition metals other than Ni, Co, and Mn, and x is in the range of from zero to 0.2, wherein at least 50 mole-% of the transition metal of TM is Ni, (b) treating said electrode active material with an aqueous medium, (c) partially removing water by solid-liquid separation method, (d) treating the solid residue with an aqueous formulation of at least one heteropolyacid or its respective ammonium or lithium salt, (e) treating the residue thermally.

The present disclosure relates to a positive active material including a lithium transition metal oxide substituted with Na, W, Mg, Ti, and S, a method of preparing the same, and a lithium secondary battery having a positive electrode including the positive active material.