WO2016093400A1 - Method for preparing lithium bis(fluorosulfonyl) imide salt and intermediate product obtained from the same - Google Patents

Method for preparing lithium bis(fluorosulfonyl) imide salt and intermediate product obtained from the same Download PDF

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Publication number
WO2016093400A1
WO2016093400A1 PCT/KR2014/012204 KR2014012204W WO2016093400A1 WO 2016093400 A1 WO2016093400 A1 WO 2016093400A1 KR 2014012204 W KR2014012204 W KR 2014012204W WO 2016093400 A1 WO2016093400 A1 WO 2016093400A1
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Prior art keywords
chemical formula
imide
fonyl
lithium
lithium bis
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PCT/KR2014/012204
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French (fr)
Inventor
Sang Ryul Lee
Kyoung Chol Kim
Kyoung Hwan Kim
Sung Hong Lee
Gang Woo Lee
Ja Young Park
Ji Ung Jeon
Yoon Sung Jung
Soo Jin Kim
Seok Hee JO
Young Tae Jeon
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Chun Bo.,Ltd
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Priority to PCT/KR2014/012204 priority Critical patent/WO2016093400A1/en
Publication of WO2016093400A1 publication Critical patent/WO2016093400A1/en

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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B21/00—Nitrogen; Compounds thereof
    • C01B21/082—Compounds containing nitrogen and non-metals and optionally metals
    • C01B21/086—Compounds containing nitrogen and non-metals and optionally metals containing one or more sulfur atoms
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C303/00—Preparation of esters or amides of sulfuric acids; Preparation of sulfonic acids or of their esters, halides, anhydrides or amides
    • C07C303/34—Preparation of esters or amides of sulfuric acids; Preparation of sulfonic acids or of their esters, halides, anhydrides or amides of amides of sulfuric acids
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0568—Liquid materials characterised by the solutes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present invention relates to amethod for preparing a lithium bi s( f luorosul fonyl ) imide and an intermediate product obtained by the preparation method and, more particularly to, a method for preparing a lithium bis(f luorosulfonyl ) imide salt that includes recrystal 1 izing an intermediate product obtained in a preparation method for bis(f luorosulfonyl) imide and then using a lithium compound to prepare a lithium bi s(f luorosul fonyl ) imide salt.
  • electric condensers for small-sized high-energy density purposes such as data-related devices, communication devices, video cameras, digital still cameras, portable devices, etc.
  • electric condensers for large-sized power purposes such as electric cars, hybrid cars, auxiliary power for fuel battery car, electric power storage, etc.
  • non-aqueous electrolyte batteries such as lithium ion battery, lithium battery, lithium ion capacitor, etc.
  • the non-aqueous electrolyte batteries use, as an ion conductor, a non-aqueous electrolyte or a non-aqueous electrolyte pseudo-sol idi f ied with a gelling agent.
  • the solvent is a mixed solvent including at least one solvent selected from non- proton solvents, including ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, etc.; and the solute is a 1 i thium salt .
  • Battery capacity is one of the characteristics of the battery. In order to improve the battery capacity, it is necessary to minimize the content of impurities in the electrolyte and suppress the chemical reaction during the charging/discharging of the battery. Generally, the solvent and the solute constituting the electrolyte use materials with high purity of at least 99.0 wt .%.
  • the solvents of at least 99.9 wt.% in purity are commonly used with the progress of the high-purity technology, but the lithium salt of high purity for use as the solute is still under development.
  • lithium salts have been developed as a solute for non-aqueous electrolyte.
  • the lithium salts include lithium hexaf luorophosphate (LiPFe), lithium fluoroborate (LiBF 4 ), lithium perchlorate (L1CIO4), lithium bis(trif luorome thane sulfonyl) imide (LiN(CF3S02)2) , lithium trif luoromethane sulfonate (L1CF3SO3), lithium tris(trif luoromethane sulfonyl) methide (LiC(CF3S02)s) , etc.
  • Lithium hexaf luorophosphate is unstable to the heat and susceptible to decomposition into the hydrofluoric acid gas in the presence of water.
  • Lithium salts of organic acids such as lithium bis( trif luoromethane sulfonyl) imide (LiNCCFsSCk ⁇ ) , lithium tri f luoromethane sulfonate (L1CF3SO3), lithium tris( tri f luoromethane sulfonyl) methide, etc., are solutes that are excellent in thermal resistance but contain a high quantity of impurities, in which case the use of the solutes possibly has an adverse effect on the battery performance.
  • LiNCCFsSCk ⁇ lithium bis( trif luoromethane sulfonyl) imide
  • Li1CF3SO3 lithium tri f luoromethane sulfonate
  • Li tris( tri f luoromethane sulfonyl) methide etc.
  • lithium bis(tri f luoromethane sulfonyl) imide and lithium bis(f luorosulfonyl ) imide, which are a little or hardly susceptible to spontaneous decomposition.
  • the lithium bis(trif luoromethane sulfonyl) imide causes corrosion in regards to aluminum collectors. Therefore, lithium bis(f luorosulfonyl) imide is suggested as an alternative to lithium hexaf 1 uorophosphat e .
  • Korean Publication Patent No. 2014-0020959 (January 19, 2014) describes a method for preparing a lithium f luorosul fonate by reacting a lithium halide and a f luorosul fonic acid in the presence of a non-aqueous solvent.
  • Korean Publication Patent No. 2013-0140216 discloses a method for preparing a lithium or sodium bis(f luorosulfonyl ) imide salt that includes preparing a bis(sul fonato) imide tertiary salt, using the bis(sulfonato) imide tertiary salt to prepare a bis(f luorosulfonyl ) imide acid, and performing a cation exchange method to prepare a lithium or sodium bis(f luorosulfonyl ) imide salt.
  • a method for preparing a lithium bis(f luorosul fonyl ) imide salt that includes: (a) reacting a chlorosul fonic acid and a ch 1 or osul fonyl isocyanate to prepare a chlorosul fonyl imide; (b) reacting the chlorosul fonyl imide and a N- fluoroalkyl ammonium represented by the following chemical formula 1 to prepare an intermediate product represented by the chemical formula 2;(c) recrystal 1 izing the intermediate product in the presence of an organic solvent; and(d) reacting the recrystal 1 i zed intermediate product from the recrystal 1 izat ion step (c) and a lithium compound to prepare a lithium bis(f luorosulfonyl) imide salt,
  • Ri is hydrogen, halogen, nitro, f luoroammonia, phenyl, or Ci-C6 linear, branched or cyclic alkyl or alkoxy; and n is an integer from 0 to 10.
  • the method further includes, after the step (d) of preparing the lithium bi s( f luorosul fonyl ) imide salt, dissolving the lithium bis(f luorosulfonyl) imide salt in a solvent containing a heterocyclic compound and then eliminating impurities through a contact with a carbon substance.
  • the heterocyclic compound is a monocyclic or condensed cyclic compound having
  • the step of eliminating impurities includes letting a solvent containing a heterocyclic group with the lithium bis(f luorosul fonyl) imide salt dissolved therein to pass through blocks including filter medium type carbon nanotubes and thereby eliminating impurities.
  • the step of eliminating impurities includes letting a solvent containing a heterocyclic group with the lithium bis(f luorosul fonyl ) imide salt dissolved therein to pass through a filter of multi-layered porous panels containing carbon nanotubes and thereby eliminating impurities.
  • N-f luoroalkyl ammonium of the chemical formula 1 is N,N ⁇ di f luoroalkyl diammonium represented by the following chemical formula 3:
  • n is an integer from 0 to 10.
  • the step of preparing an intermediate product includes reacting the chlorosul fonyl imide and the N,N- cli f luoroalkyl diammonium of the chemical formula 3 to prepare an intermediate product represented by the following chemical formula 4:
  • n is an integer from 0 to 10.
  • N-f luoroalkyl ammonium of the chemical formula 1 is n,n(l,4- phenylene)bis(N-f luoroalkylammonium) represented by the following chemical formula 5:
  • n is an integer from 1 to 10.
  • the step of preparing an intermediate product includes reacting the chlorosul fonyl imide and the n,n(l,4-phenylene)bis(N ⁇ f luoroalkyl ammonium) of the chemical formula 5 to prepare an intermediate represented by the following chemical formula 6:
  • n is an integer from 1 to 10.
  • lithium bi s( f luorosul fonyl ) iinide salt prepared by the above-described preparation method.
  • a non-aqueous electrolyte comprising a lithium bis(f luorosul fonyl ) imide salt prepared by the above-described preparation method.
  • n is an integer from 0 to 10.
  • n is an integer from 0 to 10.
  • a compound represented by the following chemical formula 6 prepared by reacting a chlorosul fonyl imide and a n, n (1, 4-pheny 1 ene) bis(N-f luoroalkyl ammonium) represented by the following chemical formula 5 ⁇ '
  • n is an integer from 1 to 10.
  • the method for preparing a lithium bis(f luorosul fonyl ) imide salt and the intermediate product obtained from the preparation method according to the present invention involves recrystal 1 izing an intermediate product easy to purify through a general distillation apparatus and then using a lithium compound to yield a lithium bi s( f luorosul fonyl ) imide salt that is not only of high purity but also excellent in economical efficiency in the aspect of the whole process.
  • the individual steps may be not performed in the order as indicated by the ordinal numbers of the steps. In other words, the individual steps may be performed in the specified order, or substantially at the same time, or in the reverse order.
  • the f luorosul fonyl imide includes di (f luorosul fonyl ) imide having two f luorosul fonyl groups or N-(f luorosul fonyl )-N- (f luoroalkyl sul fonyl ) imide having a f luorosul fonyl group and a fluorinated alkyl group.
  • the chlorosul fonyl imide includes di (chlorosul fonyl) imide having two chlorosul fonyl groups or N- (chlorosul fonyl )-N-(chloroalkylsul fonyl) imide having a chlorosul fonyl group and a chlorinated alkyl group.
  • f luoroalkyl as used herein means an alkyl group having 1 to 4 carbon atoms with at least one hydrogen atom substituted by a fluorine atom and includes a f luoromethyl group, a di f luoromethyl group, a tri f luoromethyl group, a fluoroethyl group, a di f luoroethyl group, a tri fluoroethyl group, a pentaf luoroethyl group, etc.
  • the method for preparing a lithium bis(f luorosul fonyl ) imide salt and the intermediate product obtained from the preparation method according to the present invention will be described in further detail.
  • a method for preparing a lithium bis(f luorosul fonyl ) imide salt that includes: (a) reacting a chlorosulfonic acid and a chlorosul fonyl isocyanate to prepare a chlorosul fonyl imide; (b) reacting the chlorosulfonyl imide and a N- f luoroalkyl ammonium represented by the following chemical formula 1 to prepare an intermediate product represented by the following chemical formula 2; (c) recrystal 1 izing the intermediate product in the presence of an organic solvent; and (d) reacting the recrystal 1 ized intermediate product from the recrystal 1 i zat ion step (c) and a lithium compound to prepare a lithium bis(f luorosul fonyl ) imide salt, [Chemical Formula 1
  • Ri is hydrogen, halogen, nitro, f luoroammonia, phenyl, or Ci ⁇ C6 linear, branched or cyclic alkyl or alkoxy; and n is an integer from 0 to 10.
  • the step (a) of preparing a chlorosul fonyl imide includes reacting a chlorosul fonic acid and a chlorosul fonyl isocyanate to prepare a chlorosul fonyl imide in the nitrogen atmosphere.
  • a chlorosul fonic acid and a chlorosul fonyl isocyanate to prepare a chlorosul fonyl imide in the nitrogen atmosphere.
  • a chlorosul fonyl isocyanate containing a clorine atom to produce a white solid compound
  • the step (a) is carried out while the reactants are slowly heated up.
  • An abrupt increase in the temperature during the reaction can increase the formation of carbon dioxide (CO 2 ) to raise the inner pressure of the reaction container. It is therefore preferable to slowly heat the reaction container up to an inner temperature of 120 ° C and reflux the carbon dioxide (CO 2 ) produced at the same time.
  • the heat is raised up to 120 0 C and, when the carbon dioxide to be refluxed does not form, the reaction is terminated to prepare the sulfonyl imide salt.
  • the step (b) of preparing an intermediate product includes reacting the chlorosul fonyl imide and a N-f luoroalkyl ammonium of the chemical formula 1 in the presence of an organic solvent to prepare an intermediate product of the chemical formula 2; or reacting the chlorosulfonyl imide and a N,N- di f luoroalkyl diammonium of the chemical formula 3 in the presence of an organic solvent to prepare an intermediate product represented by the following chemical formula 4; or reacting the chlorosulfonyl imide and a n,n(l,4-phenylene)bis(N-f luoroalkylammonium) of the chemical formula 5 in the presence of an organic solvent to prepare an intermediate represented by the following chemical formula 6:
  • n is an integer from 0 to 10.
  • n is an integer from 1 to 10.
  • the molar ratio of the chlorosul fonyl imide to the N-f luoroalkyl ammonium of the chemical formula 1 is preferably in the range of 1:0,5 to 1:10.
  • the proportion of the N-f luoroalkyl ammonium of the chemical formula 1 is too small, the chlorosul fonyl imide can remain unreacted.
  • the proportion of the N-f luoroalkyl ammonium of the chemical formula 1 is too large, the unreacted N-f luoroalkyl ammonium is difficult to eliminate and the content of impurities greatly increases.
  • the step of preparing an intermediate product is preferably performed at 0 ° C to 200 ° C for 5 minutes to 48 hours, more preferably 1 ° C to 100 ° C for 1 hour to 24 hours.
  • the organic solvent is at least one selected from the group consisting of ethylene carbonate, propylene carbonate, butyl carbonate, ⁇ -butylolactone, ⁇ -valerolactone, dimethoxy methane, 1 ,2-climethoxy ethane, tetrahydrofuran, 4-methyl-l,3-dioxorane, methyl formate, methyl acetate, methyl propionate, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, sulforane, 3- methyl sulforane, dimethyl sulfoxide, ⁇ , ⁇ -dimethyl form amide, N-methyl oxazol idinone, valeronitri le, benzonitrile, ethyl acetate, isopropyl acetate, butyl acetate, nitro methane, and benzene.
  • the termination of the step (b) can be determined by, for example, 1 F-NMR, etc.
  • the progress of the reaction is shown as a peak for the chemical shift to the fluoro group, where the relative intensity of the peak (integral) is increased. It is therefore possible to determine the termination of the reaction by checking on the progress of the reaction through the 19 F-NMR analysis.
  • the yield of the by-products increases when the reaction time is exceedingly long, it is desirable to terminate the reaction of the step (b) of preparing an intermediate product at the point of time the peak for the target product has the greatest relative intensity.
  • the recrystal 1 izat ion step (c) is recrystal 1 izing the intermediate product in the presence of an organic solvent.
  • the recrystal 1 izat ion process may be performed according to a general purification method. More, speci f ical ly, the intermediate product is dissolved in the organic solvent and slowly cooled down to form crystals. Such a recrystal 1 izat ion procedure may be repeated at least twice.
  • the organic solvent is preferably a solvent having a low boiling temperature and forming a two-phase system with water.
  • the organic solvent includes at least one selected from the group consisting of n-hexane, benzene, ethyl acetate, hexane, cyclohexane, acetone, ethanol , aniline, toluene, dichloromethane, and dimethyl sulfoxide (DMSO) .
  • DMSO dimethyl sulfoxide
  • the preferred organic solvent is di chl or ome thane (CCI2H2).
  • the step (d) of preparing a lithium bis(f luorosul fonyl ) imide salt includes reacting the recrystal 1 ized intermediate product from the recrystal 1 izat ion step (c) and a lithium compound to prepare a lithium bis(f luorosul fonyl ) imide salt.
  • the step (d) may use a method of reacting the intermediate product with a salt containing a lithium cation or a method of having the intermediate product in contact with a cation exchange resin.
  • the molar ratio of the lithium compound to one mole of the recrystal 1 ized intermediate product is in the range of 4 to 10.
  • the substitution reaction occurs insufficiently.
  • the used amount of the lithium compound per one mole of the intermediate product is greater than 10 moles, the content of the lithium compound in the lithium bis(f luorosul fonyl ) imide salt is increased to have an increase in the content of impurities.
  • the lithium compound includes at least one selected from the group consisting of lithium hydroxide monohydrate (LiOH'l ⁇ O), lithium carbonate (L12CO3), lithium hydrogen carbonate (L1HCO3), lithium chloride (LiCl), lithium fluoride (LiF), lithium methoxide (CH 3 0Li), lithium ethoxide (EtOLi), ethyl lithium (EtLi), butyllithium (BuLi), and t-butyl 1 ithium (t-BuLi), where Et is ethyl and Bu is butyl.
  • the preferred lithium compound is lithium hydroxide monohydrate.
  • Hydrogen halide or halides can be produced in the process of preparing the lithium bis(f luorosul fonyl ) imide salt. It is however not easy to cause corrosion on the reaction container or the peripheral equipment during the preparation process, because all the reactions in the step of preparing the chlorosul fonyl imide and the step of preparing the intermediate product and the recrystal 1 izat ion step take place in the anhydrous atmosphere. However, the inside of the reaction container is apart from the anhydrous atmosphere with the progress of the preparation process, and the liquid property of the reactant solution tends to become acidic.
  • the -contact with the reactant solution containing an acidic component readily causes corrosion on the reaction container, as a result of which the impurities released from the reaction container become incorporated into the product.
  • the reaction container is made of silicon (glass), boron or stainless steel, iron (Fe), chrome (Cr) or nickel (Ni) can be incorporated into the product.
  • the recrystal 1 i zed intermediate product is reacted with the lithium hydroxide monohydrate that is an alkaline aqueous solution, the acidic component of the reactant solution is neutralized to prevent the reaction container from corrosion.
  • the by-product obtained from the step of preparing the intermediate product can form a water-soluble complex with the lithium hydroxide monohydrate. This can achieve an effective removal of the impurities.
  • the method may further include a step of eliminating impurities after the preparation step (d) of the lithium bis(f luorosul fonyl ) imide salt in order to obtain the lithium bis(f luorosul fonyl ) imide salt with high purity.
  • the step of eliminating impurities includes dissolving the lithium bis(f luorosul fonyl ) imide salt in a solvent containing a heterocyclic compound and then eliminating impurities through a contact with a carbon substance.
  • the heterocyclic compound is at least one selected from the group consisting of a heterocyclic alkyl and/or aryl .
  • the heterocyclic alkyl and/or aryl is a monocyclic or condensed cyclic compound having 5 to 15 cyclic atoms including at least one or two heteroatoms selected from N, 0 and S; and/or an aromatic cyclic compound having 5 to 12 cyclic atoms including at least one or two heteroatoms selected from N, 0 and S.
  • the heterocyclic alkyl and/or aryl is at least one selected from the group consisting of imidazole, 1- methyl imidazole, oxazole, 1,4-oxazole, 1,4-dioxane, 1,3-dioxane, 1,3- dioxolane, oxathiole, oxathiane, furan, tetrahydrofuran, tetrahydropyran, tetrahydrozol ine, 2-methyltetrahydrofuran, and methyl N-methylanthrani late.
  • the heterocyclic alkyl and/or aryl may be any organic solvent available to recrystal 1 ize the lithium bis(f luorosul fonyl ) imide salt and is not specifically limited to the above-mentioned compounds.
  • the dissolved amount of the lithium bis(f luorosulfonyl) imide salt in the organic solvent is preferably in the range of 10 to 40 wt. .
  • the dissolved amount of the lithium bis(f luorosulfonyl) imide salt in the organic solvent is less than 10 wt.%, the lithium bis(f luorosulfonyl ) imide salt is too completely dissolved to achieve recrystal 1 izat ion.
  • the lithium bis(f luorosulfonyl) imide salt in the organic solvent is greater than 40 wt.%, the lithium bis(f luorosulfonyl ) imide salt is difficult to dissolve completely under normal conditions, deteriorating the efficiency of purification.
  • the lithium bis(f luorosulfonyl) imide salt is dissolved in a solvent containing the heterocyclic compound and thereby put in contact with the carbon substance.
  • the carbon substance is an adsorbent material capable of adsorbing impurities dissolved in the solvent and may be replaced by zeolite, alumina, silica gel, ordiatomite. But, the carbon substance that has a high adsorption capacity is preferred as the adsorbent material.
  • the carbon substance may be selected from activated carbon, graphene, carbon nanotube, and fullerene. Among these, carbon nanotube is more preferable as the carbon substance in the aspect of adsorption efficiency.
  • the contact method is not specifically limited so long as it includes a step of performing an adsorptive filtration of impurities by passing the solvent through a porous panel containing carbon nanotubes or a filter filled with blocks containing carbon nanotubes.
  • a plurality of porous panels containing carbon nanotubes are laminated, where the porous panels have a plurality of pores and are asymmetrically laminated so that the pores of one porous panel are not vertically in accord with the pores of adjacent porous panels.
  • the impurities are eliminated while the solvent in which the lithium sulfonyl imide salt is dissolved passes through the pores of the porous panels.
  • the solvent is passed through the blocks containing filter medium type carbon nanotubes so that the impurities contained in the solvent can be adsorbed by the carbon nanotubes and eliminated.
  • the lithium bis(f luorosul fonyl ) imide salt may be dissolved in a solvent containing the heterocyclic compound and then subjected to recrystal 1 i zat ion. This is to enhance the efficiency of purification by way of the multi-stage purification effect .
  • the heterocyclic compound does not bond with impurities but with the lithium bis(f luorosulfonyl) imide salt only to form a solvate complex crystal.
  • the crystal obtained after recrystal 1 izat ion can be purified and filtered to yield a lithium bis(f luorosulfonyl ) imide salt with high purity alone.
  • the solvate complex crystal used in the present invention is a compound formed by an equivalent bonding between a solute and at least one solvent molecule through chemical interactions.
  • the solvate complex crystal varies in chemical stability.
  • the solvate complex crystal such as hydrate may be a crystalline solid having a bonding between the solute and the solvent not readily breakable; or a solid very unstable so that the bonding between the solute and the solvent is too loose to form a salt; or a solid with medium stability that is capable of forming a salt and readily dissolved without many steps; or a solid with the intermediate stability that is able to form a salt and ready to dissolve without many steps.
  • the molar ratio of the heterocyclic compound to the lithium bis(f luorosulfonyl) imide salt is preferably 10:1 to 1:10, more preferably 5 " -l to 1:5.
  • the solvate complex crystal is heated under vacuum at a temperature lower than the melting temperature of the solvate complex crystal.
  • the heating temperature range is preferably from the melting temperature of the solvate complex crystal minus 35 ° C to the melting temperature of the solvate complex crystal, more preferably from the melting temperature of the solvent complex crystal minus 20 ° C to the melting temperature of the solvate complex crystal.
  • the type and quantity of the impurities in the lithium bis(f luorosulfonyl) imide salt can be analyzed by the ICP emission spectrochemical analysis or NMR measurement.
  • the preferred analysis method is the NMR (Nuclear Magnetic Resonance) method.
  • the nuclides are preferably 3 ⁇ 4, 19 F, 13 C, etc. and more preferably 19 F.
  • the lithium bis(f luorosulfonyl ) imide salt obtained by the preparation method of the present invention can be used as a material for ion conductors that constitute electrochemical devices, such as batteries with charging/discharging equipment (e.g., secondary batteries, lithium secondary batteries, fuel cells, etc.), electrolyte condensers, electric double- layered capacitors, solar cells, electro-chromic display devices, and so forth.
  • batteries with charging/discharging equipment e.g., secondary batteries, lithium secondary batteries, fuel cells, etc.
  • electrolyte condensers e.g., electric double- layered capacitors, solar cells, electro-chromic display devices, and so forth.
  • the lithium bis(f luorosulfonyl ) imide salt of the present invention can also be used as a non-aqueous electrolyte, in which case it offers high ion conductivity from low to high temperatures, remarkably reduces the content of impurities to enhance the performance of the electrolyte and properly maintains the viscosity of the electrolyte to improve the mobility of lithium ions.
  • reaction container 250 g of chlorosul fonic acid and 313 g of chlorosul fonyl isocyanate are added into a 1L reaction container (flask) in the nitrogen atmosphere and mixed under agitation.
  • the reaction container is slowly heated and agitated.
  • the inner temperature of the reaction container reaches 120 0 C, the reaction container is cooled down with a stop of the agitation to obtain 413 g of chlorosul fonyl imide.
  • the chlorosul fonyl imide thus obtained is identified as bis(chlorosul fonyl ) imide through the IR (Varian 2000 FT-IF, liquid film method) analysis.
  • Example 1 50 g of the bis(chlorosul fonyl ) imide prepared in Experimental Example 1 is added to 200 g of acetonitri le. The mixture is stirred at an average temperature of 50 ° C and cooled down to 3 ° C. 35.2 g of N-fluoro methane ammonium is slowly added dropwise to the mixture, which is then stirred for 3 hours to prepare an intermediate product (Example 1).
  • Example 4 89.5 g of ⁇ , -(l,4-phenylene)bis(N-f luoro methane ammonium) is slowly added dropwise to the mixture, which is then stirred for 3 hours to prepare an intermediate product (Example 4).
  • the intermediate products are analyzed by 19 F-NMR (Unity plus 400 type, standard substance - tri f luoromethyl benzene, number of additions - 28 times). The area of each peak is measured and the conversion rate from chlorine to fluorine is quantitatively determined to identify the products of Examples 1 to 4.
  • 011 phase is distilled and dried out to yield a solid crystal.
  • the solid crystal (Examples 1 to 4) is added to 30 g of 1-methyl imidazole, and the mixture is agitated at an average temperature of 70 ° C for 12 hours. After completion of the agitation, the mixture is heated up to 200 C for 6 hours and filtered out for recrystal 1 izat ion.
  • the recrystal 1 ized product is dissolved in 1-methyl imidazole, which is then passed through a filter filled with filter medium type blocks containing carbon nanotubes at a rate of 35 m/hr to eliminate impurities through adsorption filtration.
  • Examples 1 to 4 The product (Examples 1 to 4) filtered out is stood at the room temperature for 10 hours and then subjected to a second filtration to yield a solvate complex crystal (Examples 1 to 4).
  • Examples 1 to 4 5 g of the solvate complex crystal (Examples 1 to 4) is heated up to 100 ° C for 6 hours, to 120 ° C for more 12 hours, and then to 140 ° C for more 12 hours in a vacuum oven to yield a lithium bis(f luorosul fonyl ) imide salt (Examples 1 to 4) .
  • ⁇ 1 indicates that is greater than 0.1 ppm( which is the weight detection limit) and less than 1 ppm.
  • the lithium bis(f luorosul fonyl ) imide salt obtained by the preparation method of the present invention is of high purity that the content of impurities is 3 ppm or less.
  • the present invention has an industrial applicability since it involves recrystal 1 izing an intermediate product easy to purify through a general distillation apparatus and then using a lithium compound to yield a lithium bis(f luorosul fonyl ) imide salt that is not only of high purity but also excellent in economical efficiency in the aspect of the whole process.

Abstract

The present invention is directed to a method for preparing a lithium bis(fluorosulfonyl) imide and an intermediate product obtained by the preparation method and, more particularly to, a method for preparing a lithium bis(fluorosulfonyl) imide salt that includes recrystallizing an intermediate product obtained in a preparation method for bis(fluorosulfonyl) imide and then using a lithium compound to prepare a lithium bis(fluorosulfonyl) imide salt.

Description

[DESCRIPTION]
[Invent ion Tit le]
METHOD FOR PREPARING LITHIUM BIS(FLUOROSULFONYL) IMIDE SALT AND INTERMEDIATE PRODUCT OBTAINED FROM THE SAME
[Technical Field]
The present invention relates to amethod for preparing a lithium bi s( f luorosul fonyl ) imide and an intermediate product obtained by the preparation method and, more particularly to, a method for preparing a lithium bis(f luorosulfonyl ) imide salt that includes recrystal 1 izing an intermediate product obtained in a preparation method for bis(f luorosulfonyl) imide and then using a lithium compound to prepare a lithium bi s(f luorosul fonyl ) imide salt.
[Background Art]
In recent years, electric condensers for small-sized high-energy density purposes, such as data-related devices, communication devices, video cameras, digital still cameras, portable devices, etc., and electric condensers for large-sized power purposes, such as electric cars, hybrid cars, auxiliary power for fuel battery car, electric power storage, etc., have been under spotlight. As one of the promising electric condensers, non-aqueous electrolyte batteries, such as lithium ion battery, lithium battery, lithium ion capacitor, etc., are currently under active research and development. In general, the non-aqueous electrolyte batteries use, as an ion conductor, a non-aqueous electrolyte or a non-aqueous electrolyte pseudo-sol idi f ied with a gelling agent. As for the constitution of the non-aqueous electrolyte, the solvent is a mixed solvent including at least one solvent selected from non- proton solvents, including ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, etc.; and the solute is a 1 i thium salt .
Battery capacity is one of the characteristics of the battery. In order to improve the battery capacity, it is necessary to minimize the content of impurities in the electrolyte and suppress the chemical reaction during the charging/discharging of the battery. Generally, the solvent and the solute constituting the electrolyte use materials with high purity of at least 99.0 wt .%.
In particular, the solvents of at least 99.9 wt.% in purity are commonly used with the progress of the high-purity technology, but the lithium salt of high purity for use as the solute is still under development.
Generally, a variety of lithium salts have been developed as a solute for non-aqueous electrolyte. Specific examples of the lithium salts include lithium hexaf luorophosphate (LiPFe), lithium fluoroborate (LiBF4), lithium perchlorate (L1CIO4), lithium bis(trif luorome thane sulfonyl) imide (LiN(CF3S02)2) , lithium trif luoromethane sulfonate (L1CF3SO3), lithium tris(trif luoromethane sulfonyl) methide (LiC(CF3S02)s) , etc.
Most of the perchlorates are highly explosive, so the lithium perchlorate is also very ready to explode. Lithium hexaf luorophosphate is unstable to the heat and susceptible to decomposition into the hydrofluoric acid gas in the presence of water. Lithium salts of organic acids, such as lithium bis( trif luoromethane sulfonyl) imide (LiNCCFsSCk^) , lithium tri f luoromethane sulfonate (L1CF3SO3), lithium tris( tri f luoromethane sulfonyl) methide, etc., are solutes that are excellent in thermal resistance but contain a high quantity of impurities, in which case the use of the solutes possibly has an adverse effect on the battery performance.
Hence, there have been developed alternative salts, such as lithium bis(tri f luoromethane sulfonyl) imide and lithium bis(f luorosulfonyl ) imide, which are a little or hardly susceptible to spontaneous decomposition. Unfortunately, the lithium bis(trif luoromethane sulfonyl) imide causes corrosion in regards to aluminum collectors. Therefore, lithium bis(f luorosulfonyl) imide is suggested as an alternative to lithium hexaf 1 uorophosphat e .
The synthesis method of the lithium bis(f luorosulfonyl) imide is disclosed in several documents as follows.
Korean Publication Patent No. 2014-0020959 (January 19, 2014) describes a method for preparing a lithium f luorosul fonate by reacting a lithium halide and a f luorosul fonic acid in the presence of a non-aqueous solvent.
In addition, Korean Publication Patent No. 2013-0140216 (December 23, 2013) discloses a method for preparing a lithium or sodium bis(f luorosulfonyl ) imide salt that includes preparing a bis(sul fonato) imide tertiary salt, using the bis(sulfonato) imide tertiary salt to prepare a bis(f luorosulfonyl ) imide acid, and performing a cation exchange method to prepare a lithium or sodium bis(f luorosulfonyl ) imide salt.
However, these known preparation methods leave a lot to be desired in the aspect of purification and purity and still need to be developed in the economical aspect.
[Prior Documents]
[Patent Documents]
Korean Publication Patent No. 2014-0020959 (January 19, 2014)
Korean Publication Patent No. 2013-0140216 (December 23, 2013)
[Summary of Invention]
[Technical Problem]
It is an object of the present invention to suggest a method for preparing a lithium bis(f luorosul fonyl ) imide salt and an intermediate product obtained by a method for preparing a lithium bis(f luorosul fonyl) imide, where the preparation method includes recrystal 1 izing an intermediate product obtained in the preparation method for bis(f uorosul fonyl ) imide and then using a lithium compound to prepare a lithium bis(f luorosul fonyl ) imide salt with high purity and economical efficiency. .
It is another object of the present invention to provide a highly pure lithium bis(f luorosul fonyl ) imide salt that has such a low content of impurities as not to deteriorate the battery capacity when used as an additive for non-aqueous electrolyte batteries.
[Technical Solution]
In accordance with one embodiment of the present invention to achieve the objects of the present invention, there is provided a method for preparing a lithium bis(f luorosul fonyl ) imide salt that includes: (a) reacting a chlorosul fonic acid and a ch 1 or osul fonyl isocyanate to prepare a chlorosul fonyl imide; (b) reacting the chlorosul fonyl imide and a N- fluoroalkyl ammonium represented by the following chemical formula 1 to prepare an intermediate product represented by the chemical formula 2;(c) recrystal 1 izing the intermediate product in the presence of an organic solvent; and(d) reacting the recrystal 1 i zed intermediate product from the recrystal 1 izat ion step (c) and a lithium compound to prepare a lithium bis(f luorosulfonyl) imide salt,
[Chemical Formula 1]
Figure imgf000007_0001
[Chemical Formula 2]
Figure imgf000007_0002
In the chemical formulas 1 and 2, Ri is hydrogen, halogen, nitro, f luoroammonia, phenyl, or Ci-C6 linear, branched or cyclic alkyl or alkoxy; and n is an integer from 0 to 10.
The method further includes, after the step (d) of preparing the lithium bi s( f luorosul fonyl ) imide salt, dissolving the lithium bis(f luorosulfonyl) imide salt in a solvent containing a heterocyclic compound and then eliminating impurities through a contact with a carbon substance.
The heterocyclic compound is a monocyclic or condensed cyclic compound having
5 to 15 cyclic atomsincluding at least one or two heteroatoms selected from N, 0 and S.
The step of eliminating impurities includes letting a solvent containing a heterocyclic group with the lithium bis(f luorosul fonyl) imide salt dissolved therein to pass through blocks including filter medium type carbon nanotubes and thereby eliminating impurities. Alternatively, the step of eliminating impurities includes letting a solvent containing a heterocyclic group with the lithium bis(f luorosul fonyl ) imide salt dissolved therein to pass through a filter of multi-layered porous panels containing carbon nanotubes and thereby eliminating impurities.
The N-f luoroalkyl ammonium of the chemical formula 1 is N,N~di f luoroalkyl diammonium represented by the following chemical formula 3:
[Chemical Formula 3] H
H 1 -F
I
H
In the chemical formula 3, n is an integer from 0 to 10.
In another embodiment of the present invention, the step of preparing an intermediate product includes reacting the chlorosul fonyl imide and the N,N- cli f luoroalkyl diammonium of the chemical formula 3 to prepare an intermediate product represented by the following chemical formula 4:
[Chemical Formula 4]
Figure imgf000009_0001
In the chemical formula 4, n is an integer from 0 to 10.
The N-f luoroalkyl ammonium of the chemical formula 1 is n,n(l,4- phenylene)bis(N-f luoroalkylammonium) represented by the following chemical formula 5:
[Chemical Formula 5]
Figure imgf000009_0002
In the chemical formula 5, n is an integer from 1 to 10. In further another embodiment of the present invention, the step of preparing an intermediate product includes reacting the chlorosul fonyl imide and the n,n(l,4-phenylene)bis(N~f luoroalkyl ammonium) of the chemical formula 5 to prepare an intermediate represented by the following chemical formula 6:
[Chemical Formula 6]
Figure imgf000010_0001
In the chemical formula 6, n is an integer from 1 to 10.
In still another embodiment of the present invention, there is provided a lithium bi s( f luorosul fonyl ) iinide salt prepared by the above-described preparation method.
In still another embodiment of the present invention, there is provided a non-aqueous electrolyte comprising a lithium bis(f luorosul fonyl ) imide salt prepared by the above-described preparation method.
In still another embodiment of the present invention, there is provided a compound represented by the following chemical formula 2 and prepared by reacting a chlorosul fonyl imide and a N-f luoroalkyl ammonium represented by the following chemical formula 1:
[Chemical Formula
Figure imgf000011_0001
[Chemical Formula 2]
Figure imgf000011_0002
In the chemical formulas 1 and 2,
Figure imgf000011_0003
is hydrogen, halogen, nitro, f luoroammonia, phenyl, or Ci~C6 linear, branched or cyclic alkyl or alkoxy; and n is an integer from 0 to 10.
In still another embodiment of the present invention, there is provided a compound represented by the followi ng chemical formula 4 and prepared by reacting a chlorosul fonyl imide and a Ν,Ν-dif luoroalkyl di ammonium represented by the following chemical formula 3: [Chemical Formula 3]
Figure imgf000012_0001
[Chemical Formula
Figure imgf000012_0002
In the chemical formulas 3 and 4, n is an integer from 0 to 10.
In still another embodiment of the present invention, there is provided a compound represented by the following chemical formula 6 and prepared by reacting a chlorosul fonyl imide and a n, n (1, 4-pheny 1 ene) bis(N-f luoroalkyl ammonium) represented by the following chemical formula 5·'
[Chemical Formula 5]
Figure imgf000013_0001
[Chemical Formula 6]
Figure imgf000013_0002
In the chemical formulas 5 and 6, n is an integer from 1 to 10.
[Advantageous Effects]
The method for preparing a lithium bis(f luorosul fonyl ) imide salt and the intermediate product obtained from the preparation method according to the present invention involves recrystal 1 izing an intermediate product easy to purify through a general distillation apparatus and then using a lithium compound to yield a lithium bi s( f luorosul fonyl ) imide salt that is not only of high purity but also excellent in economical efficiency in the aspect of the whole process. [Mode for Invention]
Hereinafter, a detailed description will be given as to the preferred embodiment of the present invention. The terms or words used in the specification and claims of the present invention are not to be confined to the general or dictionary meanings but to have meaning coinciding with those of terms in the related technology.
If not stated otherwise, it will be further understood that the terms "comprises" and/or "includes" throughout the specification of the present invention specify the presence of stated components but do not preclude the presence of addition of one or more other components.
If not specified definitely in association with the specific ordinal numbers, the individual steps may be not performed in the order as indicated by the ordinal numbers of the steps. In other words, the individual steps may be performed in the specified order, or substantially at the same time, or in the reverse order.
In the present invention, the f luorosul fonyl imide includes di (f luorosul fonyl ) imide having two f luorosul fonyl groups or N-(f luorosul fonyl )-N- (f luoroalkyl sul fonyl ) imide having a f luorosul fonyl group and a fluorinated alkyl group. In the same manner, the chlorosul fonyl imide includes di (chlorosul fonyl) imide having two chlorosul fonyl groups or N- (chlorosul fonyl )-N-(chloroalkylsul fonyl) imide having a chlorosul fonyl group and a chlorinated alkyl group. The term "f luoroalkyl" as used herein means an alkyl group having 1 to 4 carbon atoms with at least one hydrogen atom substituted by a fluorine atom and includes a f luoromethyl group, a di f luoromethyl group, a tri f luoromethyl group, a fluoroethyl group, a di f luoroethyl group, a tri fluoroethyl group, a pentaf luoroethyl group, etc. Hereinafter, the method for preparing a lithium bis(f luorosul fonyl ) imide salt and the intermediate product obtained from the preparation method according to the present invention will be described in further detail.
In one embodiment of the present invention, there is provided a method for preparing a lithium bis(f luorosul fonyl ) imide salt that includes: (a) reacting a chlorosulfonic acid and a chlorosul fonyl isocyanate to prepare a chlorosul fonyl imide; (b) reacting the chlorosulfonyl imide and a N- f luoroalkyl ammonium represented by the following chemical formula 1 to prepare an intermediate product represented by the following chemical formula 2; (c) recrystal 1 izing the intermediate product in the presence of an organic solvent; and (d) reacting the recrystal 1 ized intermediate product from the recrystal 1 i zat ion step (c) and a lithium compound to prepare a lithium bis(f luorosul fonyl ) imide salt, [Chemical Formula 1
Figure imgf000016_0001
[Chemical Formula 2]
Figure imgf000016_0002
In the chemical formulas 1 and 2, Ri is hydrogen, halogen, nitro, f luoroammonia, phenyl, or Ci~C6 linear, branched or cyclic alkyl or alkoxy; and n is an integer from 0 to 10.
The step (a) of preparing a chlorosul fonyl imide includes reacting a chlorosul fonic acid and a chlorosul fonyl isocyanate to prepare a chlorosul fonyl imide in the nitrogen atmosphere. As the nitrogen can react with the chlorosul fonyl isocyanate containing a clorine atom to produce a white solid compound, its supply is terminated immediately after the nitrogen atmosphere is provided in the reaction container.
The step (a) is carried out while the reactants are slowly heated up. An abrupt increase in the temperature during the reaction can increase the formation of carbon dioxide (CO2) to raise the inner pressure of the reaction container. It is therefore preferable to slowly heat the reaction container up to an inner temperature of 120 ° C and reflux the carbon dioxide (CO2) produced at the same time. As by-products form when the inner temperature of the reaction container exceeds 130 0 C, the heat is raised up to 120 0 C and, when the carbon dioxide to be refluxed does not form, the reaction is terminated to prepare the sulfonyl imide salt.
The step (b) of preparing an intermediate product includes reacting the chlorosul fonyl imide and a N-f luoroalkyl ammonium of the chemical formula 1 in the presence of an organic solvent to prepare an intermediate product of the chemical formula 2; or reacting the chlorosulfonyl imide and a N,N- di f luoroalkyl diammonium of the chemical formula 3 in the presence of an organic solvent to prepare an intermediate product represented by the following chemical formula 4; or reacting the chlorosulfonyl imide and a n,n(l,4-phenylene)bis(N-f luoroalkylammonium) of the chemical formula 5 in the presence of an organic solvent to prepare an intermediate represented by the following chemical formula 6:
[Chemical Formula 3]
Figure imgf000017_0001
[Chemical Formula 4]
Figure imgf000018_0001
In the chemical formulas 3 and 4, n is an integer from 0 to 10.
[Chemical Formula 5]
Figure imgf000018_0002
[Chemical Formula 6]
Figure imgf000018_0003
In the chemical formulas 5 and 6, n is an integer from 1 to 10.
The molar ratio of the chlorosul fonyl imide to the N-f luoroalkyl ammonium of the chemical formula 1 is preferably in the range of 1:0,5 to 1:10. When the proportion of the N-f luoroalkyl ammonium of the chemical formula 1 is too small, the chlorosul fonyl imide can remain unreacted. When the proportion of the N-f luoroalkyl ammonium of the chemical formula 1 is too large, the unreacted N-f luoroalkyl ammonium is difficult to eliminate and the content of impurities greatly increases. The step of preparing an intermediate product is preferably performed at 0 ° C to 200 ° C for 5 minutes to 48 hours, more preferably 1 ° C to 100 ° C for 1 hour to 24 hours.
The organic solvent is at least one selected from the group consisting of ethylene carbonate, propylene carbonate, butyl carbonate, γ -butylolactone, γ -valerolactone, dimethoxy methane, 1 ,2-climethoxy ethane, tetrahydrofuran, 4-methyl-l,3-dioxorane, methyl formate, methyl acetate, methyl propionate, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, sulforane, 3- methyl sulforane, dimethyl sulfoxide, Ν,Ν-dimethyl form amide, N-methyl oxazol idinone, valeronitri le, benzonitrile, ethyl acetate, isopropyl acetate, butyl acetate, nitro methane, and benzene. Among these non-proton solvents are preferred. The termination of the step (b) can be determined by, for example, 1F-NMR, etc. In other words, the progress of the reaction is shown as a peak for the chemical shift to the fluoro group, where the relative intensity of the peak (integral) is increased. It is therefore possible to determine the termination of the reaction by checking on the progress of the reaction through the 19F-NMR analysis. As the yield of the by-products increases when the reaction time is exceedingly long, it is desirable to terminate the reaction of the step (b) of preparing an intermediate product at the point of time the peak for the target product has the greatest relative intensity.
The recrystal 1 izat ion step (c) is recrystal 1 izing the intermediate product in the presence of an organic solvent. The recrystal 1 izat ion process may be performed according to a general purification method. More, speci f ical ly, the intermediate product is dissolved in the organic solvent and slowly cooled down to form crystals. Such a recrystal 1 izat ion procedure may be repeated at least twice.
The organic solvent is preferably a solvent having a low boiling temperature and forming a two-phase system with water. The organic solvent includes at least one selected from the group consisting of n-hexane, benzene, ethyl acetate, hexane, cyclohexane, acetone, ethanol , aniline, toluene, dichloromethane, and dimethyl sulfoxide (DMSO) . But the organic solvent is not specifically limited to the above-mentioned organic solvents so long as it can be used to dissolve the intermediate product. The preferred organic solvent is di chl or ome thane (CCI2H2).
The step (d) of preparing a lithium bis(f luorosul fonyl ) imide salt includes reacting the recrystal 1 ized intermediate product from the recrystal 1 izat ion step (c) and a lithium compound to prepare a lithium bis(f luorosul fonyl ) imide salt. The step (d) may use a method of reacting the intermediate product with a salt containing a lithium cation or a method of having the intermediate product in contact with a cation exchange resin. Preferably, the molar ratio of the lithium compound to one mole of the recrystal 1 ized intermediate product is in the range of 4 to 10.
When the used amount of the lithium compound per one mole of the intermediate product is less than 4 moles, the substitution reaction occurs insufficiently. When the used amount of the lithium compound per one mole of the intermediate product is greater than 10 moles, the content of the lithium compound in the lithium bis(f luorosul fonyl ) imide salt is increased to have an increase in the content of impurities.
The lithium compound includes at least one selected from the group consisting of lithium hydroxide monohydrate (LiOH'l^O), lithium carbonate (L12CO3), lithium hydrogen carbonate (L1HCO3), lithium chloride (LiCl), lithium fluoride (LiF), lithium methoxide (CH30Li), lithium ethoxide (EtOLi), ethyl lithium (EtLi), butyllithium (BuLi), and t-butyl 1 ithium (t-BuLi), where Et is ethyl and Bu is butyl. The preferred lithium compound is lithium hydroxide monohydrate.
Hydrogen halide or halides can be produced in the process of preparing the lithium bis(f luorosul fonyl ) imide salt. It is however not easy to cause corrosion on the reaction container or the peripheral equipment during the preparation process, because all the reactions in the step of preparing the chlorosul fonyl imide and the step of preparing the intermediate product and the recrystal 1 izat ion step take place in the anhydrous atmosphere. However, the inside of the reaction container is apart from the anhydrous atmosphere with the progress of the preparation process, and the liquid property of the reactant solution tends to become acidic. Thus, the -contact with the reactant solution containing an acidic component readily causes corrosion on the reaction container, as a result of which the impurities released from the reaction container become incorporated into the product. For example, when the reaction container is made of silicon (glass), boron or stainless steel, iron (Fe), chrome (Cr) or nickel (Ni) can be incorporated into the product. But, when the recrystal 1 i zed intermediate product is reacted with the lithium hydroxide monohydrate that is an alkaline aqueous solution, the acidic component of the reactant solution is neutralized to prevent the reaction container from corrosion. In addition, the by-product obtained from the step of preparing the intermediate product can form a water-soluble complex with the lithium hydroxide monohydrate. This can achieve an effective removal of the impurities.
The method may further include a step of eliminating impurities after the preparation step (d) of the lithium bis(f luorosul fonyl ) imide salt in order to obtain the lithium bis(f luorosul fonyl ) imide salt with high purity.
The step of eliminating impurities includes dissolving the lithium bis(f luorosul fonyl ) imide salt in a solvent containing a heterocyclic compound and then eliminating impurities through a contact with a carbon substance. The heterocyclic compound is at least one selected from the group consisting of a heterocyclic alkyl and/or aryl . The heterocyclic alkyl and/or aryl is a monocyclic or condensed cyclic compound having 5 to 15 cyclic atoms including at least one or two heteroatoms selected from N, 0 and S; and/or an aromatic cyclic compound having 5 to 12 cyclic atoms including at least one or two heteroatoms selected from N, 0 and S. The heterocyclic alkyl and/or aryl is at least one selected from the group consisting of imidazole, 1- methyl imidazole, oxazole, 1,4-oxazole, 1,4-dioxane, 1,3-dioxane, 1,3- dioxolane, oxathiole, oxathiane, furan, tetrahydrofuran, tetrahydropyran, tetrahydrozol ine, 2-methyltetrahydrofuran, and methyl N-methylanthrani late. The heterocyclic alkyl and/or aryl may be any organic solvent available to recrystal 1 ize the lithium bis(f luorosul fonyl ) imide salt and is not specifically limited to the above-mentioned compounds.
The dissolved amount of the lithium bis(f luorosulfonyl) imide salt in the organic solvent is preferably in the range of 10 to 40 wt. . When the dissolved amount of the lithium bis(f luorosulfonyl) imide salt in the organic solvent is less than 10 wt.%, the lithium bis(f luorosulfonyl ) imide salt is too completely dissolved to achieve recrystal 1 izat ion. When the dissolved amount of the lithium bis(f luorosulfonyl) imide salt in the organic solvent is greater than 40 wt.%, the lithium bis(f luorosulfonyl ) imide salt is difficult to dissolve completely under normal conditions, deteriorating the efficiency of purification.
The lithium bis(f luorosulfonyl) imide salt is dissolved in a solvent containing the heterocyclic compound and thereby put in contact with the carbon substance. The carbon substance is an adsorbent material capable of adsorbing impurities dissolved in the solvent and may be replaced by zeolite, alumina, silica gel, ordiatomite. But, the carbon substance that has a high adsorption capacity is preferred as the adsorbent material. The carbon substance may be selected from activated carbon, graphene, carbon nanotube, and fullerene. Among these, carbon nanotube is more preferable as the carbon substance in the aspect of adsorption efficiency. The contact method is not specifically limited so long as it includes a step of performing an adsorptive filtration of impurities by passing the solvent through a porous panel containing carbon nanotubes or a filter filled with blocks containing carbon nanotubes.
Preferably, a plurality of porous panels containing carbon nanotubes are laminated, where the porous panels have a plurality of pores and are asymmetrically laminated so that the pores of one porous panel are not vertically in accord with the pores of adjacent porous panels. The impurities are eliminated while the solvent in which the lithium sulfonyl imide salt is dissolved passes through the pores of the porous panels. Alternatively, the solvent is passed through the blocks containing filter medium type carbon nanotubes so that the impurities contained in the solvent can be adsorbed by the carbon nanotubes and eliminated.
Before or after the step (d) of eliminating impurities, the lithium bis(f luorosul fonyl ) imide salt may be dissolved in a solvent containing the heterocyclic compound and then subjected to recrystal 1 i zat ion. This is to enhance the efficiency of purification by way of the multi-stage purification effect . The heterocyclic compound does not bond with impurities but with the lithium bis(f luorosulfonyl) imide salt only to form a solvate complex crystal. Thus, the crystal obtained after recrystal 1 izat ion can be purified and filtered to yield a lithium bis(f luorosulfonyl ) imide salt with high purity alone.
The solvate complex crystal used in the present invention is a compound formed by an equivalent bonding between a solute and at least one solvent molecule through chemical interactions. The solvate complex crystal varies in chemical stability. For example, the solvate complex crystal such as hydrate may be a crystalline solid having a bonding between the solute and the solvent not readily breakable; or a solid very unstable so that the bonding between the solute and the solvent is too loose to form a salt; or a solid with medium stability that is capable of forming a salt and readily dissolved without many steps; or a solid with the intermediate stability that is able to form a salt and ready to dissolve without many steps.
The molar ratio of the heterocyclic compound to the lithium bis(f luorosulfonyl) imide salt is preferably 10:1 to 1:10, more preferably 5"-l to 1:5.
In order to obtain a lithium bi s( f luorosul fonyl ) imide salt purified from the solvate complex crystal of the heterocyclic compound and the lithium sulfonyl imide salt, the solvate complex crystal is heated under vacuum at a temperature lower than the melting temperature of the solvate complex crystal. The heating temperature range is preferably from the melting temperature of the solvate complex crystal minus 35 ° C to the melting temperature of the solvate complex crystal, more preferably from the melting temperature of the solvent complex crystal minus 20 ° C to the melting temperature of the solvate complex crystal.
The type and quantity of the impurities in the lithium bis(f luorosulfonyl) imide salt can be analyzed by the ICP emission spectrochemical analysis or NMR measurement. The preferred analysis method is the NMR (Nuclear Magnetic Resonance) method. In the NMR method, the nuclides are preferably ¾, 19F, 13C, etc. and more preferably 19F.
The lithium bis(f luorosulfonyl ) imide salt obtained by the preparation method of the present invention can be used as a material for ion conductors that constitute electrochemical devices, such as batteries with charging/discharging equipment (e.g., secondary batteries, lithium secondary batteries, fuel cells, etc.), electrolyte condensers, electric double- layered capacitors, solar cells, electro-chromic display devices, and so forth.
In addition, the lithium bis(f luorosulfonyl ) imide salt of the present invention can also be used as a non-aqueous electrolyte, in which case it offers high ion conductivity from low to high temperatures, remarkably reduces the content of impurities to enhance the performance of the electrolyte and properly maintains the viscosity of the electrolyte to improve the mobility of lithium ions.
Hereinafter, a detailed description will be given as to the preferred embodiments of the present invention, which are not limited to the specific examples or disclosure of the present invention but susceptible to many changes and modifications without departing from the scope and spirit of the present invention. Such modifications and variations which may be apparent to a person skilled in the art are intended to be included within the scope of this invention.
[Experimental Example 1]
Preparation of Chlorosul fonyl Imide
250 g of chlorosul fonic acid and 313 g of chlorosul fonyl isocyanate are added into a 1L reaction container (flask) in the nitrogen atmosphere and mixed under agitation. The reaction container is slowly heated and agitated. When the inner temperature of the reaction container reaches 120 0 C, the reaction container is cooled down with a stop of the agitation to obtain 413 g of chlorosul fonyl imide.
The chlorosul fonyl imide thus obtained is identified as bis(chlorosul fonyl ) imide through the IR (Varian 2000 FT-IF, liquid film method) analysis.
IR (neat): US(N-H) 3155, Uas(S-0) 1433, 1428, Us(S-0) 1183, US(N-S) 824 cm"1. [Experimental Example 2]
Preparation and Purification of Intermediate Product
50 g of the bis(chlorosul fonyl ) imide prepared in Experimental Example 1 is added to 200 g of acetonitri le. The mixture is stirred at an average temperature of 50 ° C and cooled down to 3 ° C. 35.2 g of N-fluoro methane ammonium is slowly added dropwise to the mixture, which is then stirred for 3 hours to prepare an intermediate product (Example 1).
71.3 g of N^I^-dif luoroethane-l,2-di ammonium is slowly added dropwise to the mixture, which is then stirred for 3 hours to prepare an intermediate product (Example 2) .
74.2 g of N-f luoro-l-phenylene methane ammonium is slowly added dropwise to the mixture, which is then stirred for 3 hours to prepare a product (Example 3).
89.5 g of Ι, -(l,4-phenylene)bis(N-f luoro methane ammonium) is slowly added dropwise to the mixture, which is then stirred for 3 hours to prepare an intermediate product (Example 4). The intermediate products are analyzed by 19F-NMR (Unity plus 400 type, standard substance - tri f luoromethyl benzene, number of additions - 28 times). The area of each peak is measured and the conversion rate from chlorine to fluorine is quantitatively determined to identify the products of Examples 1 to 4.
19F-NMR (CDsCN): δ 56.0
20 g of each product of Examples 1 to 4 is dissolved in 100 g of dichloromethane heated up to 30 ° C and then slowly cooled down to 10 ° C to yield recrystal 1 ized solid crystals.
[Experimental Example 3]
Preparation of Lithium Bi s(Fluorosul fonyl ) Imide Salt
10 g of each solid crystal (Examples 1 to 4) obtained in Experimental Example 2 is dissolved in 100 g of acetonitrile and then mixed with 5 g of distilled water in which 1 g of lithium hydroxide monohydrate is dissolved. Subsequently, the mixture is removed of the water phase, and the remaining
011 phase is distilled and dried out to yield a solid crystal.
The solid crystal (Examples 1 to 4) is added to 30 g of 1-methyl imidazole, and the mixture is agitated at an average temperature of 70 ° C for 12 hours. After completion of the agitation, the mixture is heated up to 200 C for 6 hours and filtered out for recrystal 1 izat ion. The recrystal 1 ized product is dissolved in 1-methyl imidazole, which is then passed through a filter filled with filter medium type blocks containing carbon nanotubes at a rate of 35 m/hr to eliminate impurities through adsorption filtration.
The product (Examples 1 to 4) filtered out is stood at the room temperature for 10 hours and then subjected to a second filtration to yield a solvate complex crystal (Examples 1 to 4).
5 g of the solvate complex crystal (Examples 1 to 4) is heated up to 100 ° C for 6 hours, to 120 ° C for more 12 hours, and then to 140 ° C for more 12 hours in a vacuum oven to yield a lithium bis(f luorosul fonyl ) imide salt (Examples 1 to 4) .
[Experimental Example 4]
Measurement of Impurity Content (Examples 1 to 4)
The impurity content of the lithium bis(f luorosul fonyl ) imide salt (Examples 1 to 4) obtained in Experimental Example 3 is analyzed through the 19F~NMR (CD3CN) .
Measurement instrument: JNM-GSX400 type NMR instrument (JE0L Ltd.) Solvent: Dichloroform
Reference material: Freon-11 (CFCI3)
19F-NMR (CD3CN): δ 56.0
In the following Table 1, "< 1" indicates that is greater than 0.1 ppm( which is the weight detection limit) and less than 1 ppm.
[Table 1]
Figure imgf000032_0001
As can be seen from the results of Table 1, the lithium bis(f luorosul fonyl ) imide salt obtained by the preparation method of the present inventionis of high purity that the content of impurities is 3 ppm or less.
[Industrial Applicability]
The present invention has an industrial applicability since it involves recrystal 1 izing an intermediate product easy to purify through a general distillation apparatus and then using a lithium compound to yield a lithium bis(f luorosul fonyl ) imide salt that is not only of high purity but also excellent in economical efficiency in the aspect of the whole process.

Claims

[CLAIMS] [Claim 1] A method for preparing a lithium bis(f luorosul fonyl ) imide salt, comprising:(a) reacting a chlorosul fonic acid and a chlorosul fonyl isocyanate to prepare a chlorosul fonyl imide", (b) reacting the chlorosul fonyl imide and a N-f luoroalkyl ammonium represented by the following chemical formula 1 to prepare an intermediate product represented by the following chemical formula 2; (c) recrystal 1 izing the intermediate product in the presence of an organic solvent; and (d) reacting the recrystal 1 ized intermediate product from the recrystal 1 izat ion step (c) and a lithium compound to prepare a lithium bis(f luorosul fonyl) imide salt,
[Chemical Formula 1]
Figure imgf000033_0001
[Chemical Formula 2]
C OO r
F
H2N
Ri wherein Ri is hydrogen, halogen, nitro, f luoroammonia, phenyl, or linear, branched or cyclic alkyl or alkoxy; and n is an integer from 0 to 10.
[Claim 2]
The method as claimed in claim 1, further comprising:
after the step (d) of preparing the lithium bis(f luorosulfonyl ) imide salt, dissolving the lithium bis(f luorosulfonyl ) imide salt in a solvent containing a heterocyclic compound and then eliminating impurities through a contact with a carbon substance.
[Claim 3]
The method as claimed in claim 2, wherein the heterocyclic compound is a monocyclic or condensed cyclic compound having 5 to 15 cyclic atoms including at least one or two heteroatoms selected from N, 0 and S.
[Claim 4]
The method as claimed in claim 2, wherein the step of eliminating impurities includes letting a solvent containing a heterocyclic group with the lithium bis(f luorosulfonyl) imide salt dissolved therein to pass through blocks including filter medium type carbon nano tubes and thereby eliminating impur i t ies .
[Claim 5]
The method as claimed in claim 2, wherein the step of eliminating impurities includes letting a solvent containing a heterocyclic group with the lithium bis(f luorosulfonyl) imide salt dissolved therein to pass through a filter of multi-layered porous panels containing carbon nanotubes and thereby
eliminating impurities.
[Claim 6]
The method as claimed in claim 1, wherein the N-f luoroalkyl ammonium of the chemical formula 1 is N',N-di f luoroalkyl di ammonium represented by the following chemical formula 3:
[Chemical Formula 3]
Figure imgf000035_0001
wherein n is an integer from 0 to 10.
[Claim 7]
The method as claimed in claim 6, wherein the step of preparing an intermediate product includes reacting the chlorosul fonyl imide and the N,N- di f luoroalkyl di ammonium of the chemical formula 3 to prepare an intermediate product represented by the following chemical formula 4:
[Chemical Formula 4]
Figure imgf000036_0001
wherein n is an integer from 0 to 10.
[Claim 8]
The method as claimed in claim 1, wherein the N-f luoroalkyl ammonium of the chemical formula 1 is n,n(l,4-phenylene)bis(N-f luoroalkylammonium) represented by the following chemical formula 5:
[Chemical Formula 5]
Figure imgf000036_0002
wherein n is an integer from 1 to 10.
[Claim 9]
The method as claimed in claim 8, wherein the step of preparing an intermediate product includes reacting the chlorosul fonyl imide and the n,n(l,4-phenylene)bis(N-f luoroalkylammonium) of the chemical formula 5 to prepare an intermediate represented by the following chemical formula 6: [Chemical Formula 6]
Figure imgf000037_0001
wherein n is an integer from 1 to 10.
[Claim 10]
A lithium bis(f luorosulfonyl) imide salt prepared by the preparation method as claimed in any one of claims 1 to 9.
[Claim 11]
A non-aqueous electrolyte comprising a lithium bis(f luorosulfonyl ) imide salt prepared by the preparation method as claimed in any one of claims 1 to 9.
[Claim 12]
A compound represented by the following chemical formula 2 and prepared by reacting a chlorosul fonyl imide and a N-f luoroalkyl ammonium represented by the following chemical formula l:
[Chemical Formula 1]
Figure imgf000037_0002
[Chemical Formula 2]
Figure imgf000038_0001
wherein Ri is hydrogen, halogen, nitro, f luoroammonia, phenyl, or Ci~C6 linear, branched or cyclic alkyl or alkoxy; and n is an integer from 0 to 10.
[Claim 13]
A compound represented by the following chemical formula 4 and prepared by reacting a chlorosul fonyl imide and a N,N-di f luoroalkyl diammonium represented by the following chemical formula 3·'
[Chemical Formula 3]
Figure imgf000038_0002
[Chemical Formula 4]
Figure imgf000038_0003
wherein n is an integer from 0 to 10.
[Claim 14]
A compound represented by the following chemical formula 6 and prepared by reacting a chlorosulfonyl imide and a n,n(l,4-phenylene)bis(N-f luoroalkyl ammonium) represented by the following chemical formula 5:
[Chemical Formula 5]
Figure imgf000039_0001
[Chemical Formula
Figure imgf000039_0002
wherein n is an integer from 1 to 10.
PCT/KR2014/012204 2014-12-11 2014-12-11 Method for preparing lithium bis(fluorosulfonyl) imide salt and intermediate product obtained from the same WO2016093400A1 (en)

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CN110745795A (en) * 2019-11-07 2020-02-04 兰州大学 Method for electrochemically synthesizing lithium bis (fluorosulfonate) imide
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