A zirconium phosphate represented by M1Zr.sub.2(M2PO.sub.4).sub.a(PO.sub.4).sub.b.nH.sub.2O (M1 and M2 are monovalent cations, and may be the same or different from each other; a and b are numbers satisfying 0.3<a≤1.8, 3.1≤(a+b)≤3.6, and 2a+3b=9; and n is a number satisfying 0≤n≤2.).

The invention relates to a method and system for phosphate recovery from a stream such as waste flow, sewage or another sludge stream. The method comprises the steps of: providing an incoming stream comprising an initial amount of phosphate; dosing/controlling iron salt to the stream such that precipitates are formed in the stream, wherein the precipitates comprise vivianite like structures comprising more than 60% of the initial amount of phosphate in the incoming stream, and preferably also the steps of: separating the vivianite like structures from the stream; and recovering the phosphates from the separated vivianite like structures.

A solid electrolyte (SE) composition comprising a homogeneous blend of lithium thiophosphate particles and a polyalkylene oxide, wherein the lithium thiophosphate particles have the formula xLi.sub.2S.(1−x)P.sub.2S.sub.5 wherein x is a value within a range of 0.5-0.9, and wherein said polyalkylene oxide is present in an amount of 0.1-10 wt % of the solid electrolyte. Also described herein is a solid-state lithium-based battery comprising: a) an anode; (b) a cathode; and c) the SE composition described above. Further described herein is a method for producing the SE composition, comprising: (i) homogeneously mixing Li.sub.2S, P.sub.2S.sub.5, a polyalkylene oxide, and a solvent to form a liquid solution or liquid homogeneous dispersion, and (ii) heating the liquid solution or liquid homogeneous dispersion produced in step (i) to remove the solvent and produce the SE composition.

A solid electrolyte (SE) composition comprising a homogeneous blend of lithium thiophosphate particles and a polyalkylene oxide, wherein the lithium thiophosphate particles have the formula xLi.sub.2S.(1−x)P.sub.2S.sub.5 wherein x is a value within a range of 0.5-0.9, and wherein said polyalkylene oxide is present in an amount of 0.1-10 wt % of the solid electrolyte. Also described herein is a solid-state lithium-based battery comprising: a) an anode; (b) a cathode; and c) the SE composition described above. Further described herein is a method for producing the SE composition, comprising: (i) homogeneously mixing Li.sub.2S, P.sub.2S.sub.5, a polyalkylene oxide, and a solvent to form a liquid solution or liquid homogeneous dispersion, and (ii) heating the liquid solution or liquid homogeneous dispersion produced in step (i) to remove the solvent and produce the SE composition.

A process for recovering lithium phosphate and lithium sulfate from a lithium-bearing silicate is described. The process includes adding from 800 kg/t to 1600 kg/t of sulfuric acid to a slurry of the lithium-bearing silicate and from 40 kg/t to 600 kg/t of a source of fluoride to produce a leach mixture and heating said leach mixture. A lithium-bearing solution is then separated from the leach mixture and its pH is increased sequentially to pH 3.5 to 4, pH 5.5 to 6 then pH 10.5 to 11 to precipitate, respectively, a first, second and third set of impurities therefrom. The first, second and third sets of impurities are separated from the lithium-bearing solution and lime is added to maintain a soluble Ca concentration of at least 30 mg/L. The lithium-bearing solution is then softened by adding a two sequential amounts of phosphate to precipitate fluorapatite and apatite, respectively. A third amount of phosphate is added to produce a lithium phosphate precipitate which is then separated. The separated lithium phosphate precipitate is then digested in sulphuric acid to produce a digestion mixture from which a lithium sulfate precipitate is separated. An alkali metal hydroxide is added to the separated solution to produce an alkali metal phosphate solution and this is recycled for use as phosphate in the process.

A process for recovering lithium phosphate and lithium sulfate from a lithium-bearing silicate is described. The process includes adding from 800 kg/t to 1600 kg/t of sulfuric acid to a slurry of the lithium-bearing silicate and from 40 kg/t to 600 kg/t of a source of fluoride to produce a leach mixture and heating said leach mixture. A lithium-bearing solution is then separated from the leach mixture and its pH is increased sequentially to pH 3.5 to 4, pH 5.5 to 6 then pH 10.5 to 11 to precipitate, respectively, a first, second and third set of impurities therefrom. The first, second and third sets of impurities are separated from the lithium-bearing solution and lime is added to maintain a soluble Ca concentration of at least 30 mg/L. The lithium-bearing solution is then softened by adding a two sequential amounts of phosphate to precipitate fluorapatite and apatite, respectively. A third amount of phosphate is added to produce a lithium phosphate precipitate which is then separated. The separated lithium phosphate precipitate is then digested in sulphuric acid to produce a digestion mixture from which a lithium sulfate precipitate is separated. An alkali metal hydroxide is added to the separated solution to produce an alkali metal phosphate solution and this is recycled for use as phosphate in the process.

Provided is a cathode active material including a core including a compound represented by Formula 1; and a coating layer including a phosphorus-containing compound disposed on a surface of the core:

Li.sub.1-xNa.sub.xM1.sub.αM2.sub.1-αO.sub.2  Formula 1

In Formula 1, x, M1, M2, and α are the same as defined in relation to the present specification.

The present disclosure provides a technology of eliciting the heat generation suppressing effect of trilithium phosphate (Li.sub.3PO.sub.4) in a 4 V class battery stably. The nonaqueous electrolyte secondary battery disclosed herein includes a positive electrode having a positive electrode mixture material layer, a negative electrode, and a nonaqueous electrolyte. The positive electrode has a region with an open voltage of 4.25 V (Li/Li.sup.+) or less in an operating range of the battery. The positive electrode mixture material layer includes a positive electrode active material, trilithium phosphate (Li.sub.3PO.sub.4), and lithium dihydrogenphosphate (LiH.sub.2PO.sub.4). In the nonaqueous electrolyte secondary battery disclosed herein, in an XRD pattern of the positive electrode mixture material layer, a peak intensity I.sub.A detected near 27 cm.sup.−1, and a peak intensity B detected near 22 cm.sup.−1 satisfy 0<I.sub.A/I.sub.B≤0.03. This prevents decomposition of Li.sub.3PO.sub.4 and gelation of the positive electrode mixture material layer, and the heat generation suppressing effect by Li.sub.3PO.sub.4 can be stably elicited.

The present disclosure provides a technology of eliciting the heat generation suppressing effect of trilithium phosphate (Li.sub.3PO.sub.4) in a 4 V class battery stably. The nonaqueous electrolyte secondary battery disclosed herein includes a positive electrode having a positive electrode mixture material layer, a negative electrode, and a nonaqueous electrolyte. The positive electrode has a region with an open voltage of 4.25 V (Li/Li.sup.+) or less in an operating range of the battery. The positive electrode mixture material layer includes a positive electrode active material, trilithium phosphate (Li.sub.3PO.sub.4), and lithium dihydrogenphosphate (LiH.sub.2PO.sub.4). In the nonaqueous electrolyte secondary battery disclosed herein, in an XRD pattern of the positive electrode mixture material layer, a peak intensity I.sub.A detected near 27 cm.sup.−1, and a peak intensity B detected near 22 cm.sup.−1 satisfy 0<I.sub.A/I.sub.B≤0.03. This prevents decomposition of Li.sub.3PO.sub.4 and gelation of the positive electrode mixture material layer, and the heat generation suppressing effect by Li.sub.3PO.sub.4 can be stably elicited.

A method of treating mercury-contaminated material to obtain a treated product having reduced mercury leachability includes the steps of (a) admixing the mercury-contaminated material with a reagent system comprising calcium sulfide (CaS) and trisodium phosphate (TNaP), wherein the calcium sulfide and trisodium phosphate are preferably provided at a CaS:TNaP ratio of from 2:1 to 1:2, on a dry weight reagent basis, and the reagent system is preferably provided in an amount equal to 0.4% to 5% by weight of the contaminated material; and (b) adding water as needed to achieve a moisture content of at least 5% by weight of the contaminated material.