A positive electrode active material, a method for producing the same, and a positive electrode and a lithium secondary battery in including the same are disclosed herein. In some embodiments, a method of producing a positive electrode active material includes mixing a lithium transition metal oxide and a carbon-based material having a hollow structure to form a mixture, and mechanically treating the mixture to form a carbon coating layer on the surface of the lithium transition metal oxide, wherein the carbon-based material has a chain shape, and has a specific surface area of 500 m.sup.2/g or greater, a graphitization degree (I.sub.D/I.sub.G) of 1.0 or higher, and a dibutylphthalate (DBP) absorption of 300 mL/100 g or greater.

The present disclosure generally relates to compositions comprising substrate-free crystalline 2D bismuthene, and the method of making and using the substrate-free crystalline 2D bismuthene.

Disclosed are a method for preparing a ceramic material including a compound of a formula of A.sub.2B.sub.xO.sub.y and a ceramic material prepared by the method. The method includes: mixing a first oxide of AO.sub.m and a second oxide of BO.sub.n to obtain a mixture, ball-milling the mixture until a particle size of the mixture is not greater than 1 μm with a medium selected from a group consisting of ethanol, acetone, deionized water and a combination thereof, to obtain a powder, drying the powder at a temperature in a range of 60 to 80° C., and sintering the powder with a laser irradiation having a laser wavelength of 980 nm, an irradiation power ranging from 50 to 1500 W and an irradiation period of 3 s to 8 min to obtain the ceramic material.

A method of production of a solid electrolyte, which comprises: a step of obtaining a mixture comprising a sulfide solid electrolyte and a tertiary alcohol including 9 or less carbon atoms, and a step of removing the tertiary alcohol from the mixture.

A positive electrode active material for an all-solid-state lithium-ion battery composed of particles containing crystals of a lithium metal composite oxide, wherein the particles have a layered structure and contain at least Li and a transition metal, and in powder x-ray diffraction measurement using CuKα rays, a ratio I.sub.003/I.sub.004 of an integrated intensity I.sub.104 of a diffraction peak in a range of 2θ=44.4±1° to an integrated intensity I.sub.003 of a diffraction peak in a range of 2θ=18.5±1° exceeds 1.23, and wherein a press density A when the positive electrode active material for an all-solid-state lithium-ion battery is compressed at a pressure of 45 MPa is 2.90 g/cm.sup.3 or more.

This particle contains at least one titanium compound crystal grain, and satisfies requirements 1 and 2. Requirement 1: |dA(T)/dT| of the titanium compound crystal grain satisfies 10 ppm/° C. or more at at least one temperature T1 in a range of −200° C. to 1200° C. A is (a-axis (shorter axis) lattice constant of the titanium compound crystal grain)/(c-axis (longer axis) lattice constant of the titanium compound crystal grain), and each of the lattice constants is obtained by X-ray diffractometry of the titanium compound crystal grain. Requirement 2: the particle contains a pore, and in a cross section of the particle, the pore has an average equivalent circle diameter of 0.8 μm or more and 30 μm or less, and the titanium compound crystal grain has an average equivalent circle diameter of 1 μm or more and 70 μm or less.

One aspect of the present invention is a positive active material that contains an oxide containing lithium, a transition metal element and a typical element, and having an antifluorite crystal structure, in which the transition metal element is cobalt, iron, copper, manganese, nickel, chromium, or a combination thereof, the typical element is a group 13 element, a group 14 element, phosphorus, antimony, bismuth, tellurium or a combination thereof, and a molar ratio of a content of the typical element to a total content of the transition metal element and the typical element in the oxide is more than 0.05 and 0.5 or less.

Provided is a novel solid electrolyte material of high density and high ionic conductivity, and an all-solid-state lithium ion secondary battery that utilizes the solid electrolyte material. The solid electrolyte material has a chemical composition represented by Li.sub.7-3xGa.sub.xLa.sub.3Zr.sub.2O.sub.12 (0.08≤x<0.5), has a relative density of 99% or higher, belongs to space group I-43d, in the cubic system, and has a garnet-type structure. The lithium ion conductivity of the solid electrolyte material is 2.0×10.sup.−3 S/cm or higher. The solid electrolyte material has a lattice constant a such that 1.29 nm≤a≤1.30 nm, and lithium ions occupy the 12a site, the 12b site and two types of 48e site, and gallium occupies the 12a site and the 12b site, in the crystal structure. The all-solid-state lithium ion secondary battery has a positive electrode, a negative electrode, and a solid electrolyte. The solid electrolyte is made up of the solid electrolyte material of the present invention.

A cathode active material for a lithium secondary battery comprises a lithium metal oxide that has a layered crystal structure and contains nickel and aluminum. The lithium metal oxide contains 70 mol % or more of nickel based on a total number of moles of all elements excluding lithium and oxygen. A ratio of lithium sites occupied by nickel instead of lithium among all lithium sites in the lithium metal oxide is in a range from 1% to 3.5%. A weight ratio of aluminum to nickel in the lithium metal oxide is in a range from 1/550 to 1/100.

The present invention discloses a preparation method for high density aluminum doped cobalt oxide, which comprises following steps: 1) adding a cobalt salt solution, an alkaline solution and an oxidizer to a reactor for reaction; adding an aluminum cobalt solution to the reaction system for reaction; stopping adding the aluminum cobalt solution after D50 reaches 3.5-4.0 μm, stopping the reaction when D50 reaches the desired particle size, thus obtaining aluminiferous cobalt oxyhydroxide slurry; 2) aging, dehydrating, washing and drying the aluminiferous cobalt oxyhydroxide slurry, thus obtaining aluminiferous cobalt oxyhydroxide powder; 3) calcining the aluminiferous cobalt oxyhydroxide powder, thus obtaining the target object. With the method of the present invention, doped aluminum can be perfectly embedded into cobalt oxide lattices, thus effectively enhancing the tap density and uniformity of aluminum doped cobalt oxide and improving the cycle performance and charge-discharge performance of batteries.