An object is to reduce variation in shape of crystals that are to be formed. Solutions containing respective raw materials are made in an environment where an oxygen concentration is lower than that in air, the solutions containing the respective raw materials are mixed in an environment where an oxygen concentration is lower than that in air to form a mixture solution, and with use of the mixture solution, a composite oxide is formed by a hydrothermal method.

A positive electrode for a sodium ion secondary battery includes a positive electrode active material that intercalates and deintercalates sodium ions, a conductive assistant, a binder, and a carboxylic acid, the binder containing a vinylidene fluoride-based polymer, the carboxylic acid having at least one of a boiling point and a thermal decomposition point, and whichever of the boiling point and the thermal decomposition point is lower being higher than 150 C. The carboxylic acid is preferably at least one selected from the group consisting of hydroxy acids and polycarboxylic acids.

A positive electrode for a sodium ion secondary battery includes a positive electrode active material that intercalates and deintercalates sodium ions, a conductive assistant, a binder, and a carboxylic acid, the binder containing a vinylidene fluoride-based polymer, the carboxylic acid having at least one of a boiling point and a thermal decomposition point, and whichever of the boiling point and the thermal decomposition point is lower being higher than 150 C. The carboxylic acid is preferably at least one selected from the group consisting of hydroxy acids and polycarboxylic acids.

A method for processing lithium ion battery scrap according to this invention includes a leaching step of leaching lithium ion battery scrap to obtain a leached solution; an aluminum removal step of neutralizing the leached solution to a pH range of from 4.0 to 6.0, then performing solid-liquid separation and removing aluminum in the leached solution to obtain a first separated solution; and an iron removal step of adding an oxidizing agent to the first separated solution and adjusting the pH in a range of from 3.0 to 5.0, then performing solid-liquid separation and removing iron in the first separated solution to obtain a second separated solution.

A tranition metal composite hydroxide can be used as a precursor to allow a lithium transition metal composite oxide having a small and highly uniform particle diameter to be obtained. A method also is provided for producing a transition metal composite hydroxide represented by a general formula (1) M.sub.xW.sub.sA.sub.t(OH).sub.2+, coated with a compound containing the additive element, and serving as a precursor of a positive electrode active material for nonaqueous electrolyte secondary batteries. The method includes producing a composite hydroxide particle, forming nuclei, growing a formed nucleus; and forming a coating material containing a metal oxide or hydroxide on the surfaces of composite hydroxide particles obtained through the upstream step.

Provided are polycrystalline lithium manganese oxide particles represented by Chemical Formula 1 and a method of preparing the same:
Li.sub.(1+x)Mn.sub.(2xyf)Al.sub.yM.sub.fO.sub.(4z)<Chemical Formula 1> where M is any one selected from the group consisting of boron (B), cobalt (Co), vanadium (V), lanthanum (La), titanium (Ti), nickel (Ni), zirconium (Zr), yttrium (Y), and gallium (Ga), or two or more elements thereof, 0x0.2, 0<y0.2, 0<f0.2, and 0z0.2. According to an embodiment of the present invention, limitations, such as the Jahn-Teller distortion and the dissolution of Mn.sup.2+, may be addressed by structurally stabilizing the polycrystalline lithium manganese oxide particles. Thus, life characteristics and charge and discharge capacity characteristics of a secondary battery may be improved.

Provided are polycrystalline lithium manganese oxide particles represented by Chemical Formula 1 and a method of preparing the same:
Li.sub.(1+x)Mn.sub.(2xyf)Al.sub.yM.sub.fO.sub.(4z)<Chemical Formula 1> where M is any one selected from the group consisting of boron (B), cobalt (Co), vanadium (V), lanthanum (La), titanium (Ti), nickel (Ni), zirconium (Zr), yttrium (Y), and gallium (Ga), or two or more elements thereof, 0x0.2, 0<y0.2, 0<f0.2, and 0z0.2. According to an embodiment of the present invention, limitations, such as the Jahn-Teller distortion and the dissolution of Mn.sup.2+, may be addressed by structurally stabilizing the polycrystalline lithium manganese oxide particles. Thus, life characteristics and charge and discharge capacity characteristics of a secondary battery may be improved.

A positive electrode active material, a method for the preparation thereof and a positive electrode plate, a secondary battery and an electrical device containing the same are provided. The positive electrode active material has a core-shell structure, comprising a core and a cladding layer covering at least a portion of said core, wherein said core has a chemical formula of Li.sub.aA.sub.xMn.sub.1-yB.sub.yP.sub.1-zC.sub.zO.sub.4-nD.sub.n, said cladding layer comprises a polymer containing an electron withdrawing group. The positive electrode active material of the present application enables a secondary battery to have a relatively high energy density, while further having a significantly improved rate performance, cycling performance and/or high-temperature stability.

A method of producing perovskite nanocrystalline particles using a liquid crystal includes a first operation for preparing a mixed solution including a first precursor compound, a second precursor compound, and a first solvent. a second operation for preparing a precursor solution by adding an organic ligand to the prepared mixed solution, a third operation for performing crystallization treatment after adding the prepared precursor solution to a reactor containing a liquid crystal, and a fourth operation for separating the perovskite nanocrystalline particles from the crystallized solution through a centrifugal separator.

A negative electrode material applied to a lithium battery or a sodium battery is provided. The negative electrode material is composed of a first chemical element, a second chemical element and a third chemical element with an atomic ratio of x, 1-x, and 2, wherein 0<x<1, the first chemical element is selected from the group consisting of molybdenum (Mo), chromium (Cr), tungsten (W), manganese (Mn), technetium (Tc) and rhenium (Re), the second chemical element is selected from the group consisting of Mo, Cr and W, the third chemical element is selected from the group consisting of sulfur (S), selenium (Se) and tellurium (Te), and the first chemical element is different from the second chemical element.