A positive electrode active material, which has higher capacity and excellent charge and discharge cycle performance, for a lithium-ion secondary battery is provided. The positive electrode active material includes lithium, cobalt, magnesium, oxygen, and fluorine; when a pattern obtained by powder X ray diffraction using a CuKα1 ray is subjected to Rietveld analysis, the positive electrode active material has a crystal structure having a space group R-3m, a lattice constant of an a-axis is greater than 2.814×10(−10th power) m and less than 2.817×10(−10th power) m, and a lattice constant of a c-axis is greater than 14.05×10(−10th power) m and less than 14.07×10(−10th power) m; and in analysis by X-ray photoelectron spectroscopy, a relative value of a magnesium concentration is higher than or equal to 1.6 and lower than or equal to 6.0 with the cobalt concentration regarded as 1.

The present invention relates to a positive electrode active material for a rechargeable lithium battery and a rechargeable lithium battery including same, wherein the positive electrode active material comprises a core and a surface layer formed on the surface of the core, the core comprising a first crystalline structure, the surface layer comprising a first crystalline structure and a second crystalline structure different from the first crystalline structure, the first crystalline structure being present more than the second crystalline structure in the surface layer.

Compounds, particles, and cathode active materials that can be used in lithium ion batteries are described herein. Methods of making such compounds, powders, and cathode active materials are described. The particles have a particle size distribution with a D50 ranging from 10 m to 20 m.

A particulate precursor compound for manufacturing a lithium transition metal oxide powder for use as an active positive electrode material in lithium-ion batteries, the precursor having the general formula Ni.sub.xMn.sub.yCo.sub.zA.sub.aO.sub.v(OH).sub.w, wherein 0.15<v<0.30, v+w=2, 0.30x0.75, 0.10y0.40, 0.10z0.40, A being a dopant with a0.05, and x+y+z+a=1, the precursor consisting of a crystal structure having an XRD pattern with twin peaks at 2=380.5, the twin peaks having a left peak having a peak intensity I.sub.L and a right peak having a peak intensity I.sub.R, and a peak intensity ratio R=I.sub.R/I.sub.L with R>0.7, and the XRD pattern being free of peaks belonging to either one or both of a spinel and an oxyhydroxide compound.

A positive electrode active material includes powder of composite particles including a lithium transition metal composite oxide having a lamellar rock-salt structure and a spinel phase. The spinel phase includes an oxide including lithium and at least a first element X1 selected from the group consisting of magnesium, aluminum, titanium, manganese, yttrium, zirconium, molybdenum, and tungsten, and the lithium transition metal composite oxide includes nickel or cobalt and the first element X1.

Provided positive electrode active substance particles for non-aqueous electrolyte secondary batteries which is excellent in life characteristics of a battery with respect to a repeated charging and discharging performance thereof, as well as a non-aqueous electrolyte secondary battery. A positive electrode active substance for non-aqueous electrolyte secondary batteries comprising lithium transition metal layered oxide having a composition represented by the formula: Li.sub.a(Ni.sub.xCo.sub.yMn.sub.1-x-y)O.sub.2 wherein a is 1.0a1.15; x is 0<x<1; and y is 0<y<1, in which the positive electrode active substance is in the form of secondary particles formed by aggregating primary particles thereof, and a coefficient of variation of a compositional ratio: Li/Me wherein Me is a sum of Ni, Co and Mn (Me=Ni+Co+Mn) as measured on a section of the secondary particle is not more than 25%.

Methods are presented for synthesizing a metal precursor for a cathode-active material. The methods include adding urea to a solution comprising dissolved ions of at least one transition metal selected from Mn, Co, and Ni. The methods also include increasing a pH of the aqueous solution to a threshold pH. The methods additionally include heating the aqueous solution to precipitate a compound that includes the at least one transition metal. Such heating may involve urea decomposition. Methods are also presented that include filtering the compound from the solution and contacting the compound with at least a lithium precursor to produce a reactant charge. In these methods, the reactant charge is calcined to produce the cathode-active material. Other methods are presented.

An improved process is provided for forming a precursor to a lithium metal oxide. An improved lithium metal oxide formed by calcining the precursor is also provided. The process includes providing lithium bicarbonate in a first aqueous mixture. The lithium bicarbonate is then reacted with metal acetate thereby forming a second aqueous mixture comprising metal carbonate, lithium acetate, acetic acid and water wherein the acetic acid is neutralized with lithium hydroxide thereby forming a first mixture comprising metal carbonate and lithium acetate. The first mixture is separated into a second mixture and a third mixture wherein the second mixture comprises the metal carbonate and a first portion of lithium acetate with metal carbonate and lithium acetate being in a predetermined molar ratio. The third mixture comprises a second portion of lithium acetate. The second mixture is dried thereby forming the precursor comprising metal carbonate and lithium acetate in the predetermined molar ratio.

An improved process is provided for forming a precursor to a lithium metal oxide. An improved lithium metal oxide formed by calcining the precursor is also provided. The process includes providing lithium bicarbonate in a first aqueous mixture. The lithium bicarbonate is then reacted with metal acetate thereby forming a second aqueous mixture comprising metal carbonate, lithium acetate, acetic acid and water wherein the acetic acid is neutralized with lithium hydroxide thereby forming a first mixture comprising metal carbonate and lithium acetate. The first mixture is separated into a second mixture and a third mixture wherein the second mixture comprises the metal carbonate and a first portion of lithium acetate with metal carbonate and lithium acetate being in a predetermined molar ratio. The third mixture comprises a second portion of lithium acetate. The second mixture is dried thereby forming the precursor comprising metal carbonate and lithium acetate in the predetermined molar ratio.

Doped cathode active materials, and methods of manufacture, are described. The doped cathode active materials enable energy storage devices with improved performances, including but not limited to improved energy densities and capacity retention.