A treatment process for crystallizing a metal sulfate involving pre-treating a feedstock comprising calcium, magnesium, and/or lithium impurities, the pre-treating involving pre-leaching the feedstock in the presence of a lixiviant, selectively extracting a first portion of any of the impurities from the feedstock, and forming a leached solution comprising an uncrystallized metal sulfate and any remaining impurities; and/or refining the leached solution and removing a second portion of any of the remaining impurities; and crystallizing the uncrystallized metal sulfate from the leached solution to form a crystallized metal sulfate. So processed, the crystallized metal sulfate may be battery-grade or electroplating-grade.

Provided are a battery-level Ni—Co—Mn mixed solution and a preparation method for a battery-level Mn solution, the steps thereof comprising: acid dissolution (S1), alkalization to remove impurities (S2), synchronous precipitation of calcium, magnesium, and lithium (S3), deep ageing to remove impurities (S4), synergistic extraction (S5), and refining extraction (S6). The steps of deep ageing to remove impurities (S4) and synergistic extraction (S5) comprise: performing deep ageing on a filtrate obtained from the step of synchronous precipitation of calcium, magnesium, and lithium (S3), and after performing filtration to remove impurities, obtaining an aged filtrate; using P204 to extract the aged filtrate and obtain a loaded organic phase, and subjecting the loaded organic phase to staged back-extraction to obtain the battery-level Ni—Co—Mn mixed solution and a Mn-containing solution. By means of the cooperation between the multiple process steps of synchronous precipitation of calcium, magnesium, and lithium (S3), deep ageing to remove impurities (S4), and synergistic extraction (S5), the impurity content of the obtained battery-level Ni—Co—Mn mixed solution is significantly lowered, and the battery-level Ni—Co—Mn mixed solution can be directly used to prepare a lithium battery ternary precursor material. At the same time, the battery-level Mn solution can also be obtained, which is favorable for large-scale applications of the process and increasing economic benefits.

Provided are a battery-level Ni—Co—Mn mixed solution and a preparation method for a battery-level Mn solution, the steps thereof comprising: acid dissolution (S1), alkalization to remove impurities (S2), synchronous precipitation of calcium, magnesium, and lithium (S3), deep ageing to remove impurities (S4), synergistic extraction (S5), and refining extraction (S6). The steps of deep ageing to remove impurities (S4) and synergistic extraction (S5) comprise: performing deep ageing on a filtrate obtained from the step of synchronous precipitation of calcium, magnesium, and lithium (S3), and after performing filtration to remove impurities, obtaining an aged filtrate; using P204 to extract the aged filtrate and obtain a loaded organic phase, and subjecting the loaded organic phase to staged back-extraction to obtain the battery-level Ni—Co—Mn mixed solution and a Mn-containing solution. By means of the cooperation between the multiple process steps of synchronous precipitation of calcium, magnesium, and lithium (S3), deep ageing to remove impurities (S4), and synergistic extraction (S5), the impurity content of the obtained battery-level Ni—Co—Mn mixed solution is significantly lowered, and the battery-level Ni—Co—Mn mixed solution can be directly used to prepare a lithium battery ternary precursor material. At the same time, the battery-level Mn solution can also be obtained, which is favorable for large-scale applications of the process and increasing economic benefits.

Provided are a battery-level Ni—Co—Mn mixed solution and a preparation method for a battery-level Mn solution, the steps thereof comprising: acid dissolution (S1), alkalization to remove impurities (S2), synchronous precipitation of calcium, magnesium, and lithium (S3), deep ageing to remove impurities (S4), synergistic extraction (S5), and refining extraction (S6).

The steps of deep ageing to remove impurities (S4) and synergistic extraction (S5) comprise: performing deep ageing on a filtrate obtained from the step of synchronous precipitation of calcium, magnesium, and lithium (S3), and after performing filtration to remove impurities, obtaining an aged filtrate; using P204 to extract the aged filtrate and obtain a loaded organic phase, and subjecting the loaded organic phase to staged back-extraction to obtain the battery-level Ni—Co—Mn mixed solution and a Mn-containing solution. By means of the cooperation between the multiple process steps of synchronous precipitation of calcium, magnesium, and lithium (S3), deep ageing to remove impurities (S4), and synergistic extraction (S5), the impurity content of the obtained battery-level Ni—Co—Mn mixed solution is significantly lowered, and the battery-level Ni—Co—Mn mixed solution can be directly used to prepare a lithium battery ternary precursor material. At the same time, the battery-level Mn solution can also be obtained, which is favorable for large-scale applications of the process and increasing economic benefits.

Provided are a battery-level Ni—Co—Mn mixed solution and a preparation method for a battery-level Mn solution, the steps thereof comprising: acid dissolution (S1), alkalization to remove impurities (S2), synchronous precipitation of calcium, magnesium, and lithium (S3), deep ageing to remove impurities (S4), synergistic extraction (S5), and refining extraction (S6).

The steps of deep ageing to remove impurities (S4) and synergistic extraction (S5) comprise: performing deep ageing on a filtrate obtained from the step of synchronous precipitation of calcium, magnesium, and lithium (S3), and after performing filtration to remove impurities, obtaining an aged filtrate; using P204 to extract the aged filtrate and obtain a loaded organic phase, and subjecting the loaded organic phase to staged back-extraction to obtain the battery-level Ni—Co—Mn mixed solution and a Mn-containing solution. By means of the cooperation between the multiple process steps of synchronous precipitation of calcium, magnesium, and lithium (S3), deep ageing to remove impurities (S4), and synergistic extraction (S5), the impurity content of the obtained battery-level Ni—Co—Mn mixed solution is significantly lowered, and the battery-level Ni—Co—Mn mixed solution can be directly used to prepare a lithium battery ternary precursor material. At the same time, the battery-level Mn solution can also be obtained, which is favorable for large-scale applications of the process and increasing economic benefits.

The invention relates to a method for obtaining a magnesium fluoride (MgF.sub.2) sol solution, comprising the steps of providing a magnesium alkoxide precursor in a non-aqueous solvent and adding 1.85 to 2.05 molar equivalents of non-aqueous hydrofluoric acid, characterized in that the reaction proceeds in the presence of a second magnesium fluoride precursor selected from the group of salts of strong, volatile acids, such as a chloride, bromide, iodide, nitrate or triflate of magnesium, or of a catalytic amount of a strong, volatile acid; and/or an additive non-magnesium fluoride precursor selected from the group of salts of strong, volatile acids, such as a chloride, bromide, iodide, nitrate or triflate of lithium, antimony, tin calcium, strontium, barium, aluminium, silicium, zirconium, titanium or zinc. The invention further relates to sol solutions, method of applying the sol solutions of the invention to surfaces as a coating, and to antireflective coatings obtained thereby.

A corrosion-resistant member including: a metal base material (10); and a corrosion-resistant coating (30) formed on the surface of the base material (10). The corrosion-resistant coating (30) is a stack of a magnesium fluoride layer (31) and an aluminum fluoride layer (32) in order from the base material (10) side. The aluminum fluoride layer (32) is a stack of a first crystalline layer (32A) containing crystalline aluminum fluoride, an amorphous layer (32B) containing amorphous aluminum fluoride, and a second crystalline layer (32C) containing crystalline aluminum fluoride in order from the magnesium fluoride layer (31) side. The first crystalline layer (32A) and the second crystalline layer (32C) are layers in which diffraction spots are observed in electron beam diffraction images obtained by electron beam irradiation and the amorphous layer (32B) is a layer in which a halo pattern is observed in an electron beam diffraction image obtained by electron beam irradiation.

A corrosion-resistant member including: a metal base material (10); and a corrosion-resistant coating (30) formed on the surface of the base material (10). The corrosion-resistant coating (30) is a stack of a magnesium fluoride layer (31) and an aluminum fluoride layer (32) in order from the base material (10) side. The aluminum fluoride layer (32) is a stack of a first crystalline layer (32A) containing crystalline aluminum fluoride, an amorphous layer (32B) containing amorphous aluminum fluoride, and a second crystalline layer (32C) containing crystalline aluminum fluoride in order from the magnesium fluoride layer (31) side. The first crystalline layer (32A) and the second crystalline layer (32C) are layers in which diffraction spots are observed in electron beam diffraction images obtained by electron beam irradiation and the amorphous layer (32B) is a layer in which a halo pattern is observed in an electron beam diffraction image obtained by electron beam irradiation.

A window module includes: a window; a first anti-reflection layer disposed on the window; and a second anti-reflection layer disposed on the first anti-reflection layer, including magnesium fluoride and having a refractive index smaller than a refractive index of the first anti-reflection layer.

A window module includes: a window; a first anti-reflection layer disposed on the window; and a second anti-reflection layer disposed on the first anti-reflection layer, including magnesium fluoride and having a refractive index smaller than a refractive index of the first anti-reflection layer.