A positive-electrode active material contains a lithium composite oxide containing at least one selected from the group consisting of F, Cl, N, and S. The crystal structure of the lithium composite oxide belongs to a space group C2/m. An XRD pattern of the lithium composite oxide comprises a first peak within the first range of 44 degrees to 46 degrees of a diffraction angle 2θ and a second peak within the second range of 18 degrees to 20 degrees of the diffraction angle 2θ. The ratio of the second integrated intensity of the second peak to the first integrated intensity of the first peak is within a range of 0.05 to 0.90.

Exemplary embodiments of positive electrode active materials in the form of single particles, and a method of preparing each of them, are provided. The single particles of the exemplary embodiments include single particles of a nickel-based lithium composite metal oxide, having a plurality of crystal grains, each having a size of 180 nm to 300 nm, as analyzed by a Cu Kα X-ray (X-rα). The single particles include a metal doped in the crystal lattice thereof. One embodiment includes a surface coating. The total content of the metal doped in the crystal lattice thereof and the metal of the metal oxide coated on the surface thereof is controlled in the range of 2500 ppm to 6000 ppm.

A cathode active material for a lithium secondary battery includes lithium transition metal oxide particles, wherein the lithium transition metal oxide particles may include first lithium transition metal oxide particles (first particles) including an interparticular pore and second lithium transition metal oxide particles (second particles) having an average particle diameter within a range of a diameter of the interparticular pore, measured by mercury intrusion porosimetry. By including first particles including an interparticular pore and second particles having an average particle diameter within a range of a diameter of the interparticular pore measured by mercury intrusion porosimetry, the cathode active material may have a reduced interparticular pore present therein. Accordingly, the cathode active material may have an improved pellet density. Consequently, when a lithium secondary battery is manufactured using the cathode active material, the energy density thereof may improve.

This disclosure relates to an SO.sub.2-based electrolyte for a rechargeable battery cell containing at least one conducting salt of the Formula (I) ##STR00001##
wherein M is a metal selected from the group consisting of alkali metals, alkaline earth metals, metals of group 12 of the periodic table of the elements and aluminum; x is an integer from 1 to 3; the substituents R, R.sup.2, R.sup.3 and R.sup.4 are each independently selected from the group consisting of C.sub.1-C.sub.10 alkyl, C.sub.2-C.sub.1 alkenyl, C.sub.2-C.sub.1 alkynyl, C.sub.3-C.sub.10 cycloalkyl, C.sub.6-C.sub.14 aryl, and C.sub.5-C.sub.14 heteroaryl; and Z is aluminum or boron.

The present invention provides a positive electrode active material for a secondary battery, which includes a core, a shell disposed to surround the core, and a buffer layer which is disposed between the core and the shell and includes pores and a three-dimensional network structure connecting the core and the shell, wherein, the core, the shell, and the three-dimensional network structure of the buffer layer each independently include a lithium nickel manganese cobalt-based composite metal oxide and at least one metallic element of the nickel, the manganese, and the cobalt has a concentration gradient that gradually changes in any one region of the core, the shell, and the entire positive electrode active material.

A positive electrode material includes a first powder. The first powder includes first secondary particles. The first secondary particles includes at least two first primary particles. An average particle diameter D1 of the first primary particles is 500 nm to 3 μm. An average particle diameter D2 of the first secondary particles is 2 μm to 8 μm. A ratio K1 of D2 to D1 satisfies: 2≤K1≤10. The first powder includes an element Co and optionally further includes a metal element M. The metal element M includes at least one of Mn, Al, W, Ti, Zr, Mg, La, Y, Sr, or Ce. A molar ratio R1 between Co and M is greater than or equal to 5. The positive electrode material achieves relatively high rate performance and safety on the basis of achieving a relatively high energy density.

The present disclosure provides a lithium-rich carbonate precursor, a preparation method therefor, and an application thereof. The lithium-rich carbonate precursor has a solid spherical structure, and the chemical formula of the lithium-rich carbonate precursor is Ni.sub.xCo.sub.yMn.sub.(1−x−y)CO.sub.3. The precursor has the advantages of having controllable particle size, uniform particle size distribution, high sphericity, high tap density, good fluidity, and excellent electrochemical performance and energy density.

A ternary positive electrode material, a method for preparing the same, a positive electrode sheet and a lithium ion battery in which the ternary positive electrode material has a chemical composition of Li.sub.a(Ni.sub.xCo.sub.yM.sub.1-x-y).sub.1-bM′bO.sub.2-cA.sub.c, wherein 0.75≤a≤1.2, 0.5≤x<1, 0<y≤0.1, 0≤b≤0.01, 0≤c≤0.2; M is at least one selected from the group consisting of Mn and Al; M′ is at least one selected from the group consisting of Al, Zr, Ti, Y, Sr, W and Mg; A is at least one selected from the group consisting of S, F and N; and 2%≤C.sub.Col−C.sub.Co, 5%≤C.sub.Al−C.sub.All. The lithium ion battery shows better short-term kinetic performances and long-term kinetic performances, and it also exhibits excellent stability in long-term cycles.

A method for reusing a positive electrode active material includes dry-milling a positive electrode scrap comprising an active material layer on a current collector to convert the active material layer into a powdered state and to separate the active material layer from the current collector. The active material layer is a lithium composite transition metal oxide positive material active material layer. The method further includes adding a lithium precursor to a the active material layer. The method further includes thermally treating the active material layer in the powdered state to collect an active material. The method further includes obtaining a reusable active material by washing the collected active material with a basic lithium compound aqueous solution and drying the collected active material.

A cathode active material for a lithium secondary battery according to an embodiment of the present invention includes a plurality of a lithium-transition metal composite oxide particle having a shape of a secondary particle in which a plurality of primary particles are aggregated. The lithium-transition metal composite oxide particle includes a lithium-molybdenum-containing portion having a hexagonal close-packed structure formed between the primary particles.