A positive electrode active material includes 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 lithium-containing inorganic compound layer formed on a surface of the nickel-containing lithium transition metal oxide, wherein the positive electrode active material has a first peak in a range of 5 eV or less, a second peak in a range of 7 eV to 13 eV, and a third peak in a range of 20 eV to 30 eV when intensity is measured by X-ray photoelectron spectroscopy, and the first peak has a maximum value of 80% to 120% with respect to the third peak. A method of preparing the positive electrode active material, and a positive electrode and a lithium secondary battery are also provided.

A positive electrode active material for a secondary battery includes a lithium composite transition metal oxide comprising nickel (Ni), cobalt (Co), and manganese (Mn), and a coating layer formed on surfaces of the lithium composite transition metal oxide, wherein, in the lithium composite transition metal oxide, an amount of the nickel (Ni) in a total amount of transition metals is 60 mol % or more, and an amount of the manganese (Mn) is greater than an amount of the cobalt (Co), and the coating layer comprises a compound represented by Formula 1:

Li.sub.aM.sup.1.sub.bO.sub.c [Formula 1]

wherein, M1 includes aluminum (Al) and at least one selected from the group consisting of boron (B), silicon (Si), titanium (Ti), and phosphorus (P), and 1a4, 1b8, and 1c20.

A process produces salt by way of strong brine concentration after sea water desalination by using a two-way circulation method and bromine extraction. The process includes the following steps: A, preparing fresh water and strong brine from sea water in a high-pressure reverse osmosis unit by using a reverse osmosis method, wherein the concentration of the prepared strong brine is 70000 to 80000 PPM; and B, performing fresh and concentrated separation on the strong brine with the concentration of 70000 to 80000 PPM in a two-way circulation manner by using a concentration difference method till the strong brine is crystallized.

An inorganic solid state electrolyte includes a metal cation selected from Li.sup.+, Na.sup.+, Mg.sup.2+, Ca.sup.2+, Zn.sup.2+, or Al.sup.3+, and a single phase crystalline solution with a first borate cluster anion and at least one second borate cluster anion different than the first borate cluster anion. The first borate cluster anion and the at least one second borate cluster anion have the same number of vertices, but a different number of hydrogens exchanged with a halogen atom selected from F, Cl, Br, I, or a combination thereof. The inorganic solid state electrolyte also has an elastic modulus of less than 15 GPa and supports a coulombic efficiency of metal or alloy anode charging/discharging greater than 99%.

A non-linear optical crystal, such as a Lithium triborate (LiB.sub.3O.sub.5 or LBO) crystal, includes a first nanostructured optical surface including distributed pillars and gaps having random heights and cross sections to provide anti-reflection control and scatter control of first light incident on the first structured optical surface. The LBO crystal has an anti-reflective random structured optical surface formed by selective substitution of the surface species Boron-pentoxide (B.sub.3O.sub.5.sup.) by Lithium Fluoride (LiF), resulting in a depletion layer with low reflectivity and low reflective scatter in the visible, ultraviolet (UV), and near infrared (IR) bands. The LBO crystal with the anti-reflective structured optical surface may be a monolithic structure and thus need not include a coating of an anti-reflective (AR) material, although the LBO crystal may include an optical surface coated by an AR material. The pillars and gaps may be randomly distributed or periodically distributed on the optical surface.

A non-linear optical crystal includes a nanostructured optical surface including distributed pillars and voids to provide anti-reflection and scatter control of light incident on an optical surface. The crystal with the anti-reflective structured optical surface may be a monolithic structure and thus need not include a coating of an anti-reflective (AR) material. The pillars and gaps may be randomly distributed on the optical surface to form a gradient optical index.

The present disclosure relates to a method for processing a liquid by-product of sodium borohydride hydrolysis to obtain a borate compound, the method comprising the following steps: separating the liquid by-product by sedimentation, to obtain a borate-rich supernatant; drying the borate-rich supernatant under vacuum to obtain a solid composition comprising a borate compound. An aspect of the present disclosure relates composition obtainable by the disclosed method comprising at least 90% (w/w) of sodium boron hydroxide and its use as a source of borate in the production of sodium borohydride and/or hydrogen.

The present invention generally discloses a metalloid metal oxide coating composition of Formula (I) for the alkali mixed metal oxide based battery cathode. The coating of said composition reduces reaction based degradation of the cathode as well as electrolyte, thereby improving performance, cycle life, and rate capacity of the battery. The present invention further relates to a method of preparing the coated cathode active material and process thereof.

Disclosed are cathode active material (CAM) coated with a lithium carbonate doped with lithium borate with a formula of Li.sub.2+xC.sub.1xB.sub.xO.sub.3 wherein 0<x<0.5 and a preparation method therefor. Also disclosed is a cathode layer comprising the coated CAM in the form of particles. In one embodiment, an all-solid-state battery comprising the cathode layer exhibits improved stability and cycling performance.