Method for producing low-acid lithium borate salts and mixtures of low-acid lithium borate salts and lithium hydride

Abstract

A mixture of low-acid lithium borate salts and lithium hydride, to methods for producing the same and to the use thereof for battery electrolytes.

1 - 34 . (canceled) 
     
     
         35 . A mixture of crude lithium borate salts, lithium hydride and an aprotic solvent or solvent blend which does not dissolve the lithium borate salt, wherein the concentration of lithium hydride, relative to the weight of crude lithium borate salt, is at least 0.001 and at most 10 wt. % and the concentration of dissolved and undissolved solids in the solvent is at least 5 and at most 95% in total and the water content is at most 100 μmol/g and the acid content is at most 10 μmol H +  of crude lithium borate salt. 
     
     
         36 . The mixture according to  claim 35 , wherein the lithium hydride is present in powder form with an average particle size of at most 100 μm. 
     
     
         37 . A mixture according to  claim 35 , wherein the crude lithium borate salt is of formula I or formula II 
       
         
           
           
               
               
           
         
         wherein L is a chelating agent having two terminal oxygen atoms with the formula 
       
       
         
           
           
               
               
           
         
         
           and wherein 
         
         Y 1  and Y 2  together denote O, where m=0 or 1, n=0 or 1, o=0 and R 1  and R 2  independently of one another denote H, F, Cl, Br, OR(R=alkyl) or R′ (alkyl), or 
         Y 1 , Y 2 , Y 3 , Y 4  independently of one another each denote OR(R=alkyl), H, F, Cl, Br, R′ (alkyl), where m=0 or 1, n=0, o=1, or 
         Y 1 , C 1 , Y 3  and C 2  are members of a 5- or 6-membered aromatic or heteroaromatic ring (with N, O or S as heteroelement), which can optionally be substituted with alkyl, alkoxy, carboxy or nitrile, wherein Y 2  and Y 4  are omitted, with n=0 and m=0 or 1, o=1. 
       
     
     
         38 . A mixture according to  claim 35 , wherein the crude lithium borate salt is selected from the group comprising lithium bis(oxalato)borate (LiBOB), lithium malonato-oxalatoborate (LiMOB), lithium glycolato-oxalatoborate (LiGOB), lithium salicylato-oxalatoborate (LiSOB), lithium lactato-oxalatoborate (LiLOB), lithium catecholato-oxalatoborate (LiBZOB), lithium difluorooxalatoborate (LiDFOB), lithium difluoromalonatoborate, lithium difluoroglycolatoborate, lithium difluorosalicylatoborate, lithium difluorolactatoborate, lithium difluorocatecholatoborate. 
     
     
         39 . A mixture according to  claim 35 , wherein the aprotic solvent or solvent blend contains aromatic or saturated hydrocarbons, perfluorinated or partially fluorinated hydrocarbons or dialkyl ethers or is selected from these. 
     
     
         40 . A solvent-free mixture of a crude lithium borate salt and lithium hydride, wherein the percentage by weight of lithium hydride is at least 0.001 and at most 10 wt. % and the water content is at most 100 μmol/g and the acid content is at most 10 μmol H + /g of crude lithium borate salt. 
     
     
         41 . A solvent-free mixture according to  claim 40 , wherein the lithium hydride is present in powder form with an average particle size of at most 100 μm. 
     
     
         42 . A solvent-free mixture according to  claim 40 , wherein that crude lithium borate salts according to formula I or formula II 
       
         
           
           
               
               
           
         
         are used, wherein L is a chelating agent having two terminal oxygen atoms with the formula 
       
       
         
           
           
               
               
           
         
         
           and wherein 
         
         Y 1  and Y 2  together denote O, where m=0 or 1, n=0 or 1, o=0 and R 1  and R 2  independently of one another denote H, F, Cl, Br, OR(R=alkyl) or R′ (alkyl), or 
         Y 1 , Y 2 , Y 3 , Y 4  independently of one another each denote OR(R=alkyl), H, F, Cl, Br, R′ (alkyl), where m=0 or 1, n=0, o=1, or 
         Y 1 , C 1 . Y 3  and C 2  are members of a 5- or 6-membered aromatic or heteroaromatic ring (with N, O or S as heteroelement), which can optionally be substituted with alkyl, alkoxy, carboxy or nitrile, wherein Y 2  and Y 4  are omitted, with n=0 and m=0 or 1, o=1. 
       
     
     
         43 . A solvent-free mixture according to  claim 40 , wherein the crude lithium borate salt is selected from the group comprising lithium bis(oxalato)borate (LiBOB), lithium malonato-oxalatoborate (LiMOB), lithium glycolato-oxalatoborate (LiGOB), lithium salicylato-oxalatoborate (LiSOB), lithium lactato-oxalatoborate (LiLOB), lithium catecholato-oxalatoborate (LiBZOB), lithium difluorooxalatoborate (LiDFOB), lithium difluoro-malonatoborate, lithium difluoroglycolatoborate, lithium difluorosalicylatoborate, lithium difluorolactatoborate, lithium difluorocatecholatoborate. 
     
     
         44 . A solution of a lithium borate salt in an aprotic solvent which dissolves the lithium borate salt or an aprotic solvent blend, wherein the concentration of the lithium borate salt is at least 1 and at most 50%, preferably at least 5 and at most 30%, and the contamination with water is at most 100 μmol/g and that with acids at most 10 μmol H +  per g of dissolved lithium borate salt. 
     
     
         45 . A solution of a lithium borate salt according to  claim 44 , wherein lithium borate salts according to formula I or formula II 
       
         
           
           
               
               
           
         
         wherein L is a chelating agent having two terminal oxygen atoms with the general formula 
       
       
         
           
           
               
               
           
         
         
           and wherein 
         
         Y 1  and Y 2  together denote O, where m=0 or 1, n=0 or 1, o=0 and R 1  and R 2  independently of one another denote H, F, Cl, Br, OR(R=alkyl) or R′ (alkyl), or 
         Y 1 , Y 2 , Y 3 , Y 4  independently of one another each denote OR(R=alkyl), H, F, Cl, Br, R′ (alkyl), where m=0 or 1, n=0, o=1, or 
         Y 1 , C 1 , Y 3  and C 2  are members of a 5- or 6-membered aromatic or heteroaromatic ring (with N, O or S as heteroelement), which can optionally be substituted with alkyl, alkoxy, carboxy or nitrile, wherein Y 2  and Y 4  are omitted, with n=0 and m=0 or 1, o=1. 
       
     
     
         46 . A solution of a lithium borate salt according to  claim 44 , wherein the lithium-borate-salt-dissolving aprotic solvent contains ethers, ketones, carbonic acid esters, γ-lactones, carboxylic acid esters and/or nitriles or consists of these. 
     
     
         47 . A process for producing a mixture according to  claim 35  of crude lithium borate salts, lithium hydride and an aprotic solvent or solvent blend which does not dissolve the lithium borate salt, wherein a crude lithium borate salt in the solid phase or in suspension is brought into contact with an aprotic solvent or solvent blend which does not dissolve the lithium borate salt and lithium hydride, and stirred or otherwise mixed in an appropriate way so that all or some of the protic contaminants react to form neutral or insoluble products. 
     
     
         48 . A process according to  claim 47 , wherein the concentration of lithium hydride relative to the amount of crude lithium borate salt is 0.001 to 10%. 
     
     
         49 . A process according to  claim 47 , wherein mixing takes place in a mixing unit with exclusion of air and moisture. 
     
     
         50 . A process according to  claim 47 , wherein the purification operation is preferably performed under inert gas or under vacuum and furthermore at elevated temperatures, generally between 40 and 280° C. 
     
     
         51 . A process according to  claim 47 , wherein the aprotic solvent or solvent blend which does not dissolve lithium borate salt boils in the range between 110 and 280° C. 
     
     
         52 . A process according to  claim 47 , wherein the solvent or solvent blend contains aromatic or saturated hydrocarbons, perfluorinated or partially fluorinated hydrocarbons or dialkyl ethers. 
     
     
         53 . A process according to  claim 47 , wherein the aprotic solvent or solvent blend comprises at least one member selected from the group consisting of toluene, ethylene benzene, xylenes, cumene, heptane, octane, nonane, decane, undecane, dodecane, perfluoro(methyldecalin), perfluorononane, perfluorooctane, perfluorodecane, perfluorodecalin, perfluorokerosenes, dibutyl ether, diamyl ether and diphenyl ether. 
     
     
         54 . A process according to  claim 47 , wherein drying and neutralization preferably take place at temperatures of between 110 and 220° C. and under pressures of less than 50 mbar. 
     
     
         55 . A process according to  claim 47 , wherein drying and neutralization take place under reflux conditions in the presence of an aprotic solvent which does not dissolve the lithium borate salt and water is completely or partially separated off by azeotropic distillation. 
     
     
         56 . A process for producing a solvent-free mixture of crude lithium borate salts and lithium hydride wherein the percentage by weight of lithium hydride is at least 0.001 and at most 10 wt. % and the water content is at most 100 μmol/g and the acid content is at most 10 μmol H + /g of crude lithium borate salt, wherein the process steps according to  claim 47  are performed and then the aprotic solvent which does not dissolve the lithium borate salt is removed from the mixture of lithium borate salt and lithium hydride either by distillation or by mechanical solid/liquid separation. 
     
     
         57 . A process according to  claim 56 , wherein the removal of the aprotic solvent by distillation preferably takes place under reduced pressure. 
     
     
         58 . A process for producing a solution of a lithium borate salt according to  claim 44 , wherein a crude lithium borate salt-containing substance that is a solvent-free mixture of a crude lithium borate salt and lithium hydride, wherein the percentage by weight of lithium hydride is at least 0.001 and at most 10 wt. % and the water content is at most 100 μmol/g and the acid content is at most 10 μmol H + /g of crude lithium borate salt, is brought into contact with a solvent or solvent blend which dissolves the crude lithium borate salt and the crude lithium borate salt is dissolved therein. 
     
     
         59 . A process according to  claim 58 , wherein the constituents which are insoluble in the aprotic solvent or solvent blend are removed by a solid/liquid separation operation. 
     
     
         60 . A process for producing a clear solution of an anhydrous lithium borate salt in an aprotic solvent according to  claim 58 , wherein insoluble constituents are removed by either filtration or centrifugation. 
     
     
         61 . A process for producing a pure lithium borate salt from clear solutions according to  claim 58 , wherein the lithium borate salt is obtained from the clear solution by one of the operations total evaporation, displacement crystallisation, evaporative crystallisation or a combination of the cited processes and isolated in solid form. 
     
     
         62 . A process according to  claim 58 , wherein as crude lithium borate salts those having the general formula I or formula II 
       
         
           
           
               
               
           
         
         are used, wherein L is a chelating agent having two terminal oxygen atoms with the formula 
       
       
         
           
           
               
               
           
         
         
           and wherein 
         
         Y 1  and Y 2  together denote O, where m=0 or 1, n=0 or 1, o=0 and R 1  and R 2  independently of one another denote H, F, Cl, Br, OR(R=alkyl) or R′ (alkyl), or 
         Y 1 , Y 2 , Y 3 , Y 4  independently of one another each denote OR(R=alkyl), H, F, Cl, Br, R′ (alkyl), where m=0 or 1, n=0, o=1, or 
         Y 1 , C 1 , Y 3  and C 2  are members of a 5- or 6-membered aromatic or heteroaromatic ring (with N, O or S as heteroelement), which can optionally be substituted with alkyl, alkoxy, carboxy or nitrile, wherein Y 2  and Y 4  are omitted, with n=0 and m=0 or 1, o=1. 
       
     
     
         63 . A process according to  claim 58 , wherein the aprotic solvent which dissolves the crude lithium borate salt contains ethers, ketones, carbonic acid esters, carboxylic acid esters, γ-lactones and/or nitriles or consists thereof. 
     
     
         64 . A process according to  claim 58 , wherein the aprotic solvent which dissolves the crude lithium borate salt additionally contains a hydrocarbon. 
     
     
         65 . A process according to  claim 58 , wherein the aprotic solvent which dissolves the crude lithium borate salt is selected from the group comprising ethylene carbonate, propylene carbonate, butylene carbonate, γ-butyrolactone or γ-valerolactone. 
     
     
         66 . A process according to  claim 58 , wherein the separation of insoluble constituents takes place by membrane filtration, wherein the pore size of the filter material is less than 0.5 μm. 
     
     
         67 . A battery electrolyte comprising the mixture of  claim 35  and an additive. 
     
     
         68 . A battery electrolyte according to  claim 67 , further comprising an additive selected from the group consisting of a film-forming substance and a redox shuttle molecule.