A method for preparing a positive electrode active material for a secondary battery is provided. The method includes providing a lithium complex transition metal oxide which contains nickel (Ni) and cobalt (Co), and contains at least one selected from the group consisting of manganese (Mn) and aluminum (Al); removing lithium by-products present on a surface of the lithium complex transition metal oxide by washing the lithium complex transition metal oxide with water; and mixing the washed lithium complex transition metal oxide, a cobalt (Co)-containing raw material, and a boron (B)-containing raw material and performing high-temperature heat treatment at a temperature of 600 C. or higher.

A positive electrode active material includes a lithium transition metal oxide represented by Formula 1, and a lithium-containing inorganic compound layer formed on a surface of the lithium transition metal oxide,

Li.sub.1+a(Ni.sub.bCo.sub.cX.sub.dM.sup.1.sub.eM.sup.2.sub.f).sub.1aO.sub.2 [Formula 1] in Formula 1, X is at least one selected from the group consisting of manganese (Mn) and aluminum (Al), M.sup.1 is at least one selected from the group consisting of sulfur (S), fluorine (F), phosphorus (P), and nitrogen (N), M.sup.2 is at least one selected from the group consisting of zirconium (Zr), boron (B), cobalt (Co), tungsten (W), magnesium (Mg), cerium (Ce), tantalum (Ta), titanium (Ti), strontium (Sr), barium (Ba), hafnium (Hf), F, P, S, lanthanum (La), and yttrium (Y), 0a0.1, 0.6b0.99, 0c0.2, 0d0.2, 0<e0.1, and 0<f0.1. A method of preparing the positive electrode active material, a positive electrode and a lithium secondary battery are also provided.

A compound strontium fluoroborate, nonlinear optical crystal of strontium fluoroborate, preparation method thereof; the chemical formula of the compound is SrB5O7F3, its molecular weight is 310.67, and it is prepared by solid-state reaction; the chemical formula of the crystal is SrB5O7F3, its molecular weight is 310.67, the crystal is of the orthorhombic series, the space group is Ccm21, and the crystal cell parameters are=10.016(6) , b=8.654(6)(4) , c=8.103(5) , Z=4, and V=702.4(8) 3. A SrB5O7F3 nonlinear optical crystal has uses in the preparation of a harmonic light output when doubling, tripling, quadrupling, quintupling, or sextupling the frequency of a 1064-nm fundamental-frequency light outputted by a Nd:YAG laser, or the generation of a deep-ultraviolet frequency doubling light output lower than 200 nm, or in the preparation of a frequency multiplier, upper or lower frequency converter, or an optical parametric oscillator.

A process for recovering valuable products from ore containing boron and lithium, such as jadarite ore, includes an acid digestion step and downstream steps that recover valuable boron-containing and lithium-containing products.

In order to provide a novel oriented apatite-type oxide ion conductor which can achieve an increase in area through suppression of crack generation and preferably can be manufactured more inexpensively by an uncomplicated process, an oriented apatite-type oxide ion conductor composed of a composite oxide represented by A.sub.9.33+x[T.sub.6yM.sub.y]O.sub.26.00+z A in the formula is one kind or two or more kinds of elements selected from the group consisting of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Be, Mg, Ca, Sr, and Ba. T in the formula is an element including Si, Ge, or both of them. M in the formula is one kind or two or more kinds of elements selected from the group consisting of B, Ge, Zn, Sn, W, and Mo.

A calcium metaborate birefringent crystal and a preparation method and use thereof, the crystal having a chemical formula of CaB.sub.2O.sub.4 and a molecular weight of 125.70, and belonging to the orthorhombic crystal system and space group Pbcn with unit-cell parameters a=11.60(4), b=4.28(8), c=6.21(6), and Z=4, wherein the calcium metaborate birefringent crystal is a negative biaxial crystal with a transmission range of 165-3400 nm and a birefringence between 0.09-0.36; the crystal is applicable to infrared-visible-ultraviolet-deep ultraviolet bands, and is grown by a melt method, a flux method, a Bridgman method or a heat exchange method; the crystal obtained by the method of the present invention is easy to grow and easy to process; and can be used for making polarizing beam-splitting prisms.

A positive electrode active material including a nickel-containing lithium transition metal oxide containing nickel in an amount of 60 mol % or more based on a total number of moles of transition metals excluding lithium, and a coating layer which is formed on a surface of the nickel-containing lithium transition metal oxide and includes a lithium-containing inorganic compound, a nickel oxide, and a nickel oxyhydroxide is provided. A method of preparing the positive electrode active material, and a positive electrode for a lithium secondary battery and a lithium secondary battery which include the positive electrode active material are also provided.

A positive electrode active material including a nickel-containing lithium transition metal oxide containing nickel in an amount of 60 mol % or more based on a total number of moles of transition metals excluding lithium, and a coating layer which is formed on a surface of the nickel-containing lithium transition metal oxide and includes a lithium-containing inorganic compound, a nickel oxide, and a nickel oxyhydroxide is provided. A method of preparing the positive electrode active material, and a positive electrode for a lithium secondary battery and a lithium secondary battery which include the positive electrode active material are also provided.

Provided is a positive electrode active material that has high output characteristics and battery capacity when used for a positive electrode of a nonaqueous electrolyte secondary battery and can inhibit gelation of positive electrode mixture paste. A method for producing the positive electrode active material is also provided. A positive electrode active material for a nonaqueous electrolyte secondary battery contains a lithium-nickel-cobalt-manganese composite oxide represented by General Formula (1): Li.sub.i+sNi.sub.xCo.sub.yMn.sub.zB.sub.LM1.sub.uO.sub.2+ and having a hexagonal layered crystal structure. The lithium-nickel-cobalt-manganese composite oxide contains a secondary particle formed of a plurality of flocculated primary particles and a boron compound containing lithium present at least on part of surfaces of the primary particles. A water-soluble Li amount present on the surfaces of the primary particles is up to 0.1% by mass relative to the entire amount of the positive electrode active material.

Provided is a positive electrode active material that has high output characteristics and battery capacity when used for a positive electrode of a nonaqueous electrolyte secondary battery and can inhibit gelation of positive electrode mixture paste. A method for producing the positive electrode active material is also provided. A positive electrode active material for a nonaqueous electrolyte secondary battery contains a lithium-nickel-cobalt-manganese composite oxide represented by General Formula (1): Li.sub.i+sNi.sub.xCo.sub.yMn.sub.zB.sub.LM1.sub.uO.sub.2+ and having a hexagonal layered crystal structure. The lithium-nickel-cobalt-manganese composite oxide contains a secondary particle formed of a plurality of flocculated primary particles and a boron compound containing lithium present at least on part of surfaces of the primary particles. A water-soluble Li amount present on the surfaces of the primary particles is up to 0.1% by mass relative to the entire amount of the positive electrode active material.