JP2007123171A - Nonaqueous electrolyte composition and nonaqueous electrolyte secondary battery using the composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a nonaqueous electrolyte composition for a nonaqueous electrolyte secondary battery having excellent cycle characteristics and excellent low temperature characteristics. <P>SOLUTION: A glycol ether compound represented by formula (1) is used as an organic solvent in the nonaqueous electrolyte composition prepared by dissolving an electrolyte salt in the organic solvent. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention provides a non-aqueous electrolyte composition using an organic solvent containing a glycol ether compound having a specific structure, and a non-aqueous electrolyte secondary battery using the composition. By using the compound in the electrolyte solution, the rate of change in electric capacity and internal resistance is small during repeated charging and discharging, and the increase in internal resistance at low temperatures is small, so it has excellent cycle characteristics and low temperature characteristics that maintain high electric capacity. A non-aqueous electrolyte secondary battery is provided.

  With the spread of portable electronic devices such as portable personal computers and handy video cameras in recent years, non-aqueous electrolyte secondary batteries having high voltage and high energy density are widely used as power sources. In addition, due to environmental problems, battery cars and hybrid vehicles using electric power as a part of power have been put into practical use.

  However, the non-aqueous electrolyte secondary battery exhibits a decrease in electric capacity or an increase in internal resistance at low temperatures or by repeated charge and discharge, and lacks reliability as a stable power supply source.

  Various additives have been proposed to improve the stability and electrical characteristics of non-aqueous electrolyte secondary batteries. For example, it has been proposed to use a fluorobenzene compound as an organic solvent in an organic solvent-based electrolyte (see Patent Document 1 and Patent Document 2). However, although cycle characteristics have been improved, there is a drawback in that the capacity decreases. Further, it has been proposed to add a methoxybenzene compound to the electrolytic solution (see Patent Document 3 and Patent Document 4), but although the capacity has been increased, the cycle characteristics and the low temperature characteristics have not been satisfactory. Furthermore, as a solvent for the electrolyte, particularly glycol ethers coordinate with bidentate to lithium ions, the lithium salt electrolyte has excellent characteristics in terms of conductivity and stability. Yes. However, when a general glycol ether such as dimethoxyethane is used for the electrolytic solution of the secondary battery, there is a problem that the surface of the negative electrode is easily decomposed, and the charging efficiency is deteriorated and the internal resistance is increased. Therefore, in secondary batteries, it is common to use a mixed solvent of chain carbonate and cyclic carbonate instead of glycol ether.

Japanese Patent No. 3354057 Japanese Patent No. 3456650 Japanese Patent Laid-Open No. 9-17447 JP-A-10-308236

  Accordingly, an object of the present invention is to provide a non-aqueous electrolyte composition from which a non-aqueous electrolyte secondary battery excellent in cycle characteristics and low-temperature characteristics can be obtained.

  As a result of intensive studies, the present inventors have found that the above object can be achieved by including a glycol ether compound having a specific structure as a solvent when producing a non-aqueous electrolyte secondary battery. Was completed.

  That is, the present invention is an organic solvent comprising a glycol ether compound represented by the following general formula (1) in a non-aqueous electrolyte composition obtained by dissolving an electrolyte salt in an organic solvent. A non-aqueous electrolyte composition characterized by the above is provided.

  According to the non-aqueous electrolyte composition of the present invention, a non-aqueous electrolyte secondary battery excellent in cycle characteristics and low-temperature characteristics can be obtained.

Hereinafter, the non-aqueous electrolyte composition of the present invention and the non-aqueous electrolyte secondary battery using the composition will be described in detail.
In the general formula (1), examples of the alkylene group having 2 to 6 carbon atoms which may be branched or cyclic represented by R include ethylene, trimethylene, tetramethylene, pentamethylene, hexamethylene and the like. These may be bonded to an oxygen atom, a nitrogen atom, or a silicon atom.
Examples of the alkyl group having 1 to 10 carbon atoms represented by X _{1 to} X ₁₀ include methyl, ethyl, propyl, butyl, sec-butyl, tert-butyl, pentyl, hexyl, heptyl, octyl 2-ethyl- Hexyl, nonyl, decyl are mentioned, and examples of the alkoxy group having 1 to 10 carbon atoms and the alkylthio group having 1 to 10 carbon atoms include methyl, ethyl, propyl, butyl, sec-butyl, tert-butyl, pentyl, hexyl , Alkoxy groups and alkylthio groups derived from heptyl, octyl 2-ethyl-hexyl, nonyl, decyl and the like.

As the glycol ether compound represented by the above general formula (1), in the above general formula (1), “a compound in which R is an ethylene group and X _{1 to} X ₁₀ are each independently a fluorine atom or a hydrogen atom” , “A compound in which R is a trimethylene group, and X _{1 to} X ₁₀ are each independently a fluorine atom or a hydrogen atom”.
More preferable examples of the glycol ether compound represented by the general formula (1) include the following compound Nos. 1-No. 7 etc. are mentioned. However, this invention is not restrict | limited at all by the following illustrations.

For example, the glycol ether compound represented by the general formula (1) used in the present invention is obtained by reacting dibromoalkylene with difluorophenol in the presence of an alkali (Williamson synthesis) to obtain a glycol ether, followed by ethyl acetate. The product is obtained by washing with a solvent such as hexane, diethyl ether or water and purifying it.
The glycol ether compound represented by the general formula (1) can be used as an organic solvent for a non-aqueous electrolyte, has excellent stability, and is less likely to increase internal resistance when used in a secondary battery. This has the advantage that the cycle characteristics are improved and the life is extended.

  The glycol ether compound represented by the general formula (1) can be used alone as an organic solvent for the non-aqueous electrolyte, but preferably one or more other solvents (for example, carbonates, lactones). And non-aqueous solvents such as ethers, sulfolanes, and dioxolanes) are used as organic solvents for non-aqueous electrolytes. In particular, it is preferable to contain at least one chain carbonate compound and at least one cyclic carbonate compound. By using this combination, not only the cycle characteristics are excellent, but also the viscosity of the electrolytic solution, the electric capacity / output of the obtained battery, etc. Can be provided.

  Examples of the chain carbonate compounds include dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), ethyl-n-butyl carbonate, methyl-t-butyl carbonate, di-i-propyl carbonate, t- Examples include butyl-i-propyl carbonate. Examples of the cyclic carbonate compound include ethylene carbonate (EC), propylene carbonate (PC), vinylene carbonate (VC), 1,2-butylene carbonate, and isobutylene carbonate.

  Examples of the other organic solvents include cyclic ester compounds such as γ-butyrolactone and γ-valerolactone, sulfolanes such as sulfolane, sulfolene, tetramethylsulfolane, diphenylsulfone, dimethylsulfone and dimethylsulfoxide, and N-methyl. Amide compounds such as pyrrolidone, dimethylformamide, dimethylacetamide and the like can be mentioned.

Further, as the other organic solvent, a chain or cyclic ether compound that has a low viscosity and can improve the performance of the electrolyte solution at a low temperature may be used. Such chain or cyclic ether compounds include dimethoxyethane (DME), ethoxymethoxyethane, diethoxyethane, tetrahydrofuran, dioxolane, dioxane, 1,2-bis (methoxycarbonyloxy) ethane, 1,2-bis (ethoxycarbonyl). Oxy) ethane, 1,2-bis (ethoxycarbonyloxy) propane, ethylene glycol bis (trifluoroethyl) ether, i-propylene glycol (trifluoroethyl) ether, ethylene glycol bis (trifluoromethyl) ether, diethylene glycol bis ( (Trifluoroethyl) ether and the like.
Furthermore, chain ester compounds such as methyl formate, ethyl formate, methyl acetate, ethyl acetate, propyl acetate, sec-butyl acetate, butyl acetate, methyl propionate and ethyl propionate can be used, and other acetonitrile and propionitrile Nitromethane and derivatives thereof can also be used.

The content of the glycol ether compound represented by the general formula (1) is preferably 0.5 to 60% by volume, and particularly preferably 1 to 50% by volume in the total organic solvent. Moreover, it is preferable that the compounding quantity of organic solvents other than the glycol ether compound represented by the said General formula (1) mix | blended as needed is 0-99 volume% in all the organic solvents.
Moreover, it is preferable that content of the glycol ether compound represented by the said General formula (1) is 0.5-60 mass parts with respect to 100 mass parts of electrolyte solution which melt | dissolved electrolyte salt in the organic solvent.

  In the non-aqueous electrolyte composition of the present invention, generally known additives may be added in order to impart more excellent cycle characteristics.

  In addition, in order to impart flame retardancy to the non-aqueous electrolyte composition of the present invention, halogen-based, phosphorus-based, and other flame retardants can be added as appropriate. Examples of the phosphorus flame retardant include phosphoric esters such as trimethyl phosphate and triethyl phosphate, melamine polyphosphate, ammonium polyphosphate, ethylene diamine polyphosphate, hexamethylene diamine polyphosphate, piperazine polyphosphate, and the like. .

  5-100 mass parts is preferable with respect to 100 mass parts of all the organic solvents which comprise a non-aqueous electrolyte composition, and, as for the usage-amount of flame retardants, such as the said phosphorus flame retardant, 10-50 mass parts is especially preferable. If it is less than 5 parts by mass, a sufficient flame retarding effect cannot be obtained.

As the electrolyte salt in the non-aqueous electrolyte composition of the present invention, a conventionally known electrolyte can be used. For example, LiPF ₆ , LiBF ₄ , LiAsF ₆ , LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) _{2 , LiC (CF 3 SO 2)} 3, LiSbF 6, LiSiF 5, LiAlF 4, LiSCN, LiClO 4, LiCl, LiF, LiBr, LiI, LiAlF 4, LiAlCl 4, NaClO 4, NaBF 4, such as NaI and the like, Among these, LiPF ₆ , LiBF ₄ , LiClO ₄ and LiAsF ₆ which are inorganic salts, and LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiC (CF ₃ SO ₂ ) ₃ and derivatives thereof which are organic salts. One or more types selected from the group consisting of are preferable because of their excellent electrical characteristics.

  The electrolyte salt is dissolved in the organic solvent so that the concentration in the non-aqueous electrolyte composition is 0.1 to 3.0 mol / liter, particularly 0.5 to 2.0 mol / liter. Is preferred. When the concentration of the electrolyte salt in the non-aqueous electrolyte composition is less than 0.1 mol / liter, a sufficient current density may not be obtained. There is a risk of damage.

  The non-aqueous electrolyte secondary battery of the present invention uses the non-aqueous electrolyte composition of the present invention as the non-aqueous electrolyte, and materials other than the non-aqueous electrolyte such as electrode materials and separators are particularly The various materials conventionally used for the nonaqueous electrolyte secondary battery can be used as they are without limitation.

Examples of the electrode material include a positive electrode and a negative electrode. As the positive electrode, a material obtained by applying a slurry of a positive electrode active material, a binder and a conductive material to a current collector and drying it into a sheet can be used. Examples of the positive electrode active material include TiS ₂ , TiS ₃ , MoS ₃ , FeS ₂ , Li _(1-x) MnO ₂ , Li _(1-x) Mn ₂ O ₄ , Li _(1-x) CoO ₂ , Li _{( 1-x)} NiO ₂ , LiV ₂ O ₃ , V ₂ O _{5 and the} like. In addition, X in the illustration of this positive electrode active material shows the number of 0-1. Of these positive electrode active materials, composite oxides of lithium and transition metals are preferable, and specific examples thereof include LiCoO ₂ , LiNiO ₂ , LiMn ₂ O ₄ , LiMnO ₂ , and LiV ₂ O ₃ . Examples of the binder for the positive electrode active material include, but are not limited to, polyvinylidene fluoride, polytetrafluoroethylene, EPDM, SBR, NBR, and fluororubber.

  Examples of the conductive material for the positive electrode include graphite fine particles, carbon black such as acetylene black, and amorphous carbon fine particles such as needle coke, but are not limited thereto. As the solvent used for slurrying, an organic solvent that dissolves the above binder is usually used. Specific examples include N-methylpyrrolidone, dimethylformamide, dimethylacetamide, methyl ethyl ketone, cyclohexanone, methyl acetate, and methyl acrylate. , Diethyltriamine, NN-dimethylaminopropylamine, ethylene oxide, tetrahydrofuran and the like, but are not limited thereto. In some cases, the active material is slurried with a latex such as SBR by adding a dispersant, a thickener or the like to water.

  As the negative electrode, a negative electrode active material and a binder slurryed with a solvent is applied to a current collector and dried to form a sheet. Examples of the negative electrode active material include lithium, lithium alloys, tin compounds and other inorganic compounds, carbonaceous materials, conductive polymers, and the like. In particular, carbonaceous materials that can occlude and release highly safe lithium ions are preferable. . The carbonaceous material is not particularly limited, but graphite, petroleum-based coke, coal-based coke, petroleum-based pitch carbide, coal-based pitch carbide, phenolic resin / crystalline cellulose resin carbide, etc., and partially carbonized carbon. Examples thereof include materials, furnace black, acetylene black, pitch-based carbon fibers, and PAN-based carbon fibers. Moreover, what was illustrated as a binder and a solvent which can be used for the said positive electrode can respectively be used as the said binder and said solvent used for a negative electrode.

  Copper, nickel, stainless steel, nickel-plated steel or the like is usually used for the current collector of the negative electrode, and aluminum, stainless steel, nickel-plated steel or the like is usually used for the current collector of the positive electrode.

  In the non-aqueous electrolyte secondary battery of the present invention, a separator is used between the positive electrode and the negative electrode. As the separator, a polymer microporous film usually used for non-aqueous electrolyte secondary batteries can be used without any particular limitation. For example, polyethylene, polypropylene, polyvinylidene fluoride, polyvinylidene chloride, polyacrylonitrile, polyacrylamide, polytetrafluoroethylene, polysulfone, polyethersulfone, polycarbonate, polyamide, polyimide, polyethers such as polyethylene oxide and polypropylene oxide, carboxy Consists of various celluloses such as methylcellulose and hydroxypropylcellulose, high molecular compounds mainly composed of poly (meth) acrylic acid and various esters thereof, derivatives thereof, copolymers and mixtures thereof. Irumu and the like. Moreover, these films may be used independently and may be used as a multilayer film which laminated | stacked the several film. Furthermore, various additives may be used for these films, and the kind and content thereof are not particularly limited. Among these microporous films, a film made of polyethylene, polypropylene, polyvinylidene fluoride, or polysulfone is preferably used for the nonaqueous electrolyte secondary battery of the present invention.

  The film used as the separator is microporous so that the non-aqueous electrolyte can permeate and ions can easily pass through. This microporosification method includes a “phase separation method” in which a film of the above polymer compound and a solvent is formed while microphase separation is performed, and the solvent is extracted and removed to make it porous. Extruded into a film after drafting, heat treated, crystals are aligned in one direction, and a “stretching method” in which gaps are formed between the crystals by stretching to achieve porosity. Is done.

  A phenolic antioxidant, a phosphorus antioxidant, a thioether antioxidant, and a hindered amine compound are added to the non-aqueous electrolyte composition of the present invention, the electrode material and the separator for the purpose of improving safety. May be.

  Examples of the phenol-based antioxidant include 1,6-hexamethylene bis [(3-tert-butyl-5-methyl-4-hydroxyphenyl) propionic acid amide], 4,4′-thiobis (6-tert. Tributyl-m-cresol), 4,4′-butylidenebis (6-tert-butyl-m-cresol), 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane 1,3,5-tris (2,6-dimethyl-3-hydroxy-4-tert-butylbenzyl) isocyanurate, 1,3,5-tris (3,5-ditert-butyl-4-hydroxybenzyl) ) Isocyanurate, 1,3,5-tris (3,5-ditert-butyl-4-hydroxybenzyl) -2,4,6-trimethylbenzene, tetrakis [3- (3,5-ditert-butyl- 4- Droxyphenyl) methyl propionate] methane, thiodiethylene glycol bis [(3,5-ditert-butyl-4-hydroxyphenyl) propionate], 1,6-hexamethylenebis [(3,5-ditert-butyl- 4-hydroxyphenyl) propionate], bis [3,3-bis (4-hydroxy-3-tert-butylphenyl) butyric acid] glycol ester, bis [2-tert-butyl-4-methyl-6- (2 -Hydroxy-3-tert-butyl-5-methylbenzyl) phenyl] terephthalate, 1,3,5-tris [(3,5-ditert-butyl-4-hydroxyphenyl) propionyloxyethyl] isocyanurate, 3, 9-bis [1,1-dimethyl-2-{(3-tert-butyl-4-hydroxy-5-methylphenyl) propiyl Nyloxy} ethyl] -2,4,8,10-tetraoxaspiro [5,5] undecane, triethylene glycol bis [(3-tert-butyl-4-hydroxy-5-methylphenyl) propionate] and the like. .

  Examples of the phosphorus antioxidant include trisnonylphenyl phosphite, tris [2-tert-butyl-4- (3-tert-butyl-4-hydroxy-5-methylphenylthio) -5-methylphenyl]. Phosphite, tridecyl phosphite, octyl diphenyl phosphite, di (decyl) monophenyl phosphite, di (tridecyl) pentaerythritol diphosphite, di (nonylphenyl) pentaerythritol diphosphite, bis (2,4-di Tert-butylphenyl) pentaerythritol diphosphite, bis (2,6-ditert-butyl-4-methylphenyl) pentaerythritol diphosphite, bis (2,4,6-tritert-butylphenyl) pentaerythritol diphosphite Phosphite, bis (2,4-dicumylphenyl) pen Erythritol diphosphite, tetra (tridecyl) isopropylidene diphenol diphosphite, tetra (tridecyl) -4,4′-n-butylidenebis (2-tert-butyl-5-methylphenol) diphosphite, hexa (tridecyl) -1 , 1,3-Tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane triphosphite, tetrakis (2,4-ditert-butylphenyl) biphenylene diphosphonite, 9,10-dihydro-9 -Oxa-10-phosphaphenanthrene-10-oxide, 2,2'-methylenebis (4,6-tert-butylphenyl) -2-ethylhexyl phosphite, 2,2'-methylenebis (4,6- Tributylphenyl) -octadecyl phosphite, 2,2′-ethylidenebis (4 6-ditert-butylphenyl) fluorophosphite, tris (2-[(2,4,8,10-tetrakis tert-butyldibenzo [d, f] [1,3,2] dioxaphosphine-6 -Yl) oxy] ethyl) amine, phosphite of 2-ethyl-2-butylpropylene glycol and 2,4,6-tritert-butylphenol, and the like.

  Examples of the thioether-based antioxidant include dialkylthiodipropionates such as dilauryl thiodipropionate, dimyristyl thiodipropionate, and distearyl thiodipropionate, and pentaerythritol tetra (β-alkylmercaptopropionate esters). Is mentioned.

  Examples of the hindered amine compound include 2,2,6,6-tetramethyl-4-piperidyl stearate, 1,2,2,6,6-pentamethyl-4-piperidyl stearate, 2,2,6,6. -Tetramethyl-4-piperidylbenzoate, bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (1,2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (1-Octoxy-2,2,6,6-tetramethyl-4-piperidyl) sebacate, tetrakis (2,2,6,6-tetramethyl-4-piperidyl) -1,2,3,4-butanetetra Carboxylate, tetrakis (1,2,2,6,6-pentamethyl-4-piperidyl) -1,2,3,4-butanetetracarboxylate, bis (2,2,6 6-tetramethyl-4-piperidyl) di (tridecyl) -1,2,3,4-butanetetracarboxylate, bis (1,2,2,6,6-pentamethyl-4-piperidyl) di (tridecyl) ) -1,2,3,4-butanetetracarboxylate, bis (1,2,2,4,4-pentamethyl-4-piperidyl) -2-butyl-2- (3,5-ditert-butyl- 4-hydroxybenzyl) malonate, 1- (2-hydroxyethyl) -2,2,6,6-tetramethyl-4-piperidinol / diethyl succinate polycondensate, 1,6-bis (2,2, 6,6-tetramethyl-4-piperidylamino) hexane / 2,4-dichloro-6-morpholino-s-triazine polycondensate, 1,6-bis (2,2,6,6-tetramethyl-4- Piperidylamino) hex Sun / 2,4-dichloro-6-tert-octylamino-s-triazine polycondensate, 1,5,8,12-tetrakis [2,4-bis (N-butyl-N- (2,2,6 , 6-tetramethyl-4-piperidyl) amino) -s-triazin-6-yl] -1,5,8,12-tetraazadodecane, 1,5,8,12-tetrakis [2,4-bis ( N-butyl-N- (1,2,2,6,6-pentamethyl-4-piperidyl) amino) -s-triazin-6-yl] -1,5,8-12-tetraazadodecane, 1,6 , 11-tris [2,4-bis (N-butyl-N- (2,2,6,6-tetramethyl-4-piperidyl) amino) -s-triazin-6-yl] aminoundecane, 1,6 , 11-tris [2,4-bis (N-butyl-N- (1,2,2,6 6-pentamethyl-4-piperidyl) amino) -s-triazin-6-yl] such as aminoundecanoic the like.

  The non-aqueous electrolyte secondary battery of the present invention having the above-described configuration is not particularly limited in shape, and can be batteries having various shapes such as a flat type (button type), a cylindrical type, and a square type. . Representative examples of the non-aqueous electrolyte secondary battery of the present invention include lithium secondary batteries that use lithium or a lithium alloy or a material capable of inserting and extracting lithium ions as a negative electrode active material, but are not limited thereto. It is also possible to adopt a configuration whose structure is appropriately changed within a range not impairing the effects of the present invention. FIG. 1 shows an outline of an example of the internal structure of the non-aqueous electrolyte secondary battery of the present invention as a coin-type battery, and FIG. 2 shows the basic configuration of the cylindrical battery of the non-aqueous electrolyte secondary battery of the present invention. FIG. 3 shows an outline of an example of the internal structure of the cylindrical battery.

1, 1 is a positive electrode, 1a is a positive electrode current collector, 2 is a negative electrode, 2a is a negative electrode current collector, 3 is an electrolyte, 4 is a positive electrode case, 5 is a negative electrode case, and 6 is a gasket. , 7 are separators. 2 and 3, 11 is a negative electrode, 12 is a negative electrode current collector, 13 is a positive electrode, 14 is a positive electrode current collector, 15 is an electrolyte, 16 is a separator, and 17 is a positive electrode. Reference numeral 18 is a negative electrode terminal, 19 is a negative electrode plate, 20 is a negative electrode lead, 21 is a positive electrode, 22 is a positive electrode lead, 23 is a case, 24 is an insulating plate, 25 is a gasket, 26 is a safety valve, and 27 is a PTC element.
In the non-aqueous electrolyte secondary battery of the present invention, constituent materials other than those usually used in the non-aqueous electrolyte secondary battery can be used as necessary.

  Hereinafter, the present invention will be described in detail with reference to production examples and examples. However, this invention is not restrict | limited at all by the following manufacture examples and Examples.

(Production Example 1)
Synthesis of ethylene glycol-bis-2,4-difluorophenyl ether (Compound No. 1) In a 500 ml four-necked flask, 57.2 g (0.44 mol) of 2,4-difluorophenol and K ₂ CO ₃ were 66. 2 g (0.48 mol) and 120 g of N-dimethylacetamide (DMAc) were charged as a solvent, and 37.8 g (0.20 mol) of ethylene bromide was added dropwise at 80 ° C. over 30 minutes. Then, since salt precipitated and slurry concentration became high, it heated up to 100 degreeC. After adding 30 g of N-dimethylacetamide (DMAc) and reacting at 120 ° C. for 2 hours, 120 g of ethyl acetate, 60 g of hexane and 300 g of water were added at room temperature (25 ° C.), followed by separation. Further, it was washed with 200 g of water. The resultant was washed twice with 30 ml of 2N sodium hydroxide, the remaining phenol was removed, and further washed with 30 g of water three times. The oil layer was desolvated and recrystallized with 45 g of methanol. The obtained target product was white crystals, and the yield was 18 g, the yield was 30%, and the GC purity was 100%.

The analysis results by IR and NMR are shown below.
^{IR (cm -1): 800cm -1} , 839cm -1, 1493cm -1 ( benzene), 1214cm ^-1, 1519cm ^-1 (ether)
H ¹ -NMR (CDCl ₃ , ppm): 2.24 (q: 2H), 4.11 (t: 4H), 6.44 (m: 6H)

(Production Example 2)
Synthesis of 1,3-bis-3,5-difluorophenoxypropane (Compound No. 5) In a 50 ml four-necked flask, 19.1 g (0.147 mol) of 3,5-difluorophenol and 20 K ₂ CO ₃ were added. .3 g (0.147 mol) and 44 g of N-dimethylacetamide (DMAc) as a solvent were charged, and 13.6 g (0.061 mol) of 1,3-dibromopropane was added dropwise at 50 ° C. over 1 hour. The salt was precipitated by the dropwise addition, and the slurry concentration was increased. The mixture was further reacted at 70 ° C. for 1 hour, and separated at room temperature (25 ° C.) by adding 30 g of ethyl acetate, 15 g of hexane and 45 g of water. The resultant was washed twice with 10 ml of 2N sodium hydroxide, the remaining phenol was removed, and further washed with 10 g of water three times. The oil layer was desolvated and recrystallized with 30 g of methanol. The yield of the obtained target product was 13.6 g, the yield was 57%, and the GC purity was 100%.

The analysis results by IR and NMR are shown below.
^{IR (cm -1): 832cm -1} , 841cm -1, 1054cm -1, 1470cm -1 ( benzene), 1153cm ^-1, 1620cm ^-1 (ether)
H ¹ -NMR (CDCl ₃ , ppm): 4.38 (t: 4H), 6.79 (d: 2H), 6.87 (d: 2H), 7.03 (d: 2H)

Example 1
A lithium secondary battery was produced according to the following procedure.

(Preparation of positive electrode)
85 parts by mass of the positive electrode active material LiCoO _2, 10 parts by mass of acetylene black as a conductive agent, and 5 parts by mass of polyvinylidene fluoride (PVDF) as a binder were mixed to obtain a positive electrode material. This positive electrode material was dispersed in N-methyl-2-pyrrolidone (NMP) to form a slurry. This slurry was applied to both sides of a positive electrode current collector made of aluminum, dried and press-molded to obtain a positive electrode plate. Then, this positive electrode plate was cut into a predetermined size, and a sheet-like positive electrode was produced by scraping off the electrode mixture at a portion that became a lead tab weld for extracting current.

(Preparation of negative electrode)
A negative electrode material was prepared by mixing 7.5 parts by mass of PVDF with 92.5 parts by mass of the carbon material powder. This negative electrode material was dispersed in NMP to form a slurry. This slurry was applied to both sides of a copper negative electrode current collector, dried and press-molded to obtain a negative electrode plate. Then, this negative electrode plate was cut into a predetermined size, and a sheet-like negative electrode was produced by scraping off a portion of the electrode mixture that would become a lead tab weld for extracting current.

(Preparation of non-aqueous electrolyte composition)
LiPF ₆ was dissolved at a concentration of 1.0 mol / liter in a mixed organic solvent having the composition (volume%) shown in Table 1 and Table 2 to obtain a non-aqueous electrolyte composition. EC represents ethylene carbonate, EMC represents ethyl methyl carbonate, DMC represents dimethyl carbonate, DEC represents diethyl carbonate, and DME represents dimethoxyethane.

(Assembly of lithium secondary battery)
The sheet-like positive electrode and the sheet-like negative electrode obtained above were wound through a film made of microporous polyethylene having a thickness of 25 μm to form a wound electrode body. The obtained wound electrode body was inserted into the case and held in the case. At this time, the current collecting lead having one end welded to the lead tab welded portion of the sheet-like positive electrode and the sheet-like negative electrode was joined to the positive electrode terminal or the negative electrode terminal of the case. Thereafter, the non-aqueous electrolyte composition was injected into the case holding the wound electrode body, and the case was sealed and sealed. By the above procedure, a cylindrical lithium secondary battery having a diameter of 18 mm and an axial length of 65 mm was produced.

  The characteristics (initial output, output after 500 cycles, and discharge capacity retention after 500 cycles) of the manufactured lithium secondary battery were measured by the following measuring method. These measurements were performed at 20 ° C. and −30 ° C., respectively. The results are shown in Tables 1 and 2. However, the initial output indicated the measured value in Comparative Example 1-1 as 100.

(Initial output measurement method)
First, the battery was charged at a constant current at room temperature, and the state of charge (SOC) of the battery was adjusted to 60%. Then, the operating voltage range of the battery is set to a range from 4.1 V to 3 V, the discharge current of the battery is changed, each discharge is performed for 10 seconds, a current-voltage line at the 10th second is obtained, and the lower limit voltage is 3 V. The value of the output characteristic was calculated by multiplying the current value by the lower limit voltage of 3V.

(Output measurement method after 500 cycles)
A lithium secondary battery, placed in an ambient temperature 60 ° C. in a constant temperature bath, and constant current charging to 4.1V at a charging current 2.2 mA / cm ^2, a constant current discharge at a discharge current of 2.2 mA / cm ² to 3V The cycle to be performed was repeated 500 times. For this lithium secondary battery, the value of the output characteristic was calculated according to the above (initial output measurement method).

(Measurement method of discharge capacity maintenance rate after 500 cycles)
First, constant current and constant voltage charging was performed up to 4.1 V at a charging current of 0.25 mA / cm ² , and constant current discharging was performed up to 3.0 V at a discharging current of 0.33 mA / cm ² . Then, the charging current 1.1mA / cm ² with a constant current constant voltage charge to 4.1 V, after 4 times the constant current discharge at a discharge current of 1.1mA / cm ² to 3.0 V, charging current 1.1mA / cm ² with a constant current constant voltage charge to 4.1 V, the discharge current 0.33 mA / cm ² up to 3.0V constant current discharge, the discharge capacity at this time was a battery initial capacity. The initial battery capacity was measured in an atmosphere at 20 ° C.
A lithium secondary battery, placed in an ambient temperature 60 ° C. in a constant temperature bath, and constant current charging to 4.1V at a charging current 2.2 mA / cm ^2, a constant current discharge at a discharge current of 2.2 mA / cm ² to 3V The cycle to be performed was repeated 500 times. After that, the ambient temperature is set to the measurement temperature (20 ° C. or −30 ° C.), the charging current is 1.1 mA / cm ² and the constant current is constant voltage charging up to 4.1 V, and the discharging current is 0.33 mA / cm ² and the voltage is fixed to 3.0 V The current was discharged, and the ratio of the discharge capacity to the initial battery capacity at this time was defined as the discharge capacity retention rate (%) after 500 cycles.

FIG. 1 is a longitudinal sectional view schematically showing an example of the internal structure of a coin-type battery of the nonaqueous electrolyte secondary battery of the present invention. FIG. 2 is a schematic diagram showing a basic configuration of a cylindrical battery of the nonaqueous electrolyte secondary battery of the present invention. FIG. 3 is a perspective view showing an example of the internal structure of the cylindrical battery of the nonaqueous electrolyte secondary battery of the present invention as a cross section.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Positive electrode 1a Positive electrode collector 2 Negative electrode 2a Negative electrode collector 3 Electrolyte 4 Positive electrode case 5 Negative electrode case 6 Gasket 7 Separator 10 Coin type nonaqueous electrolyte secondary battery 10 'Cylindrical nonaqueous electrolyte secondary battery DESCRIPTION OF SYMBOLS 11 Negative electrode 12 Negative electrode assembly 13 Positive electrode 14 Positive electrode assembly 15 Electrolytic solution 16 Separator 17 Positive electrode terminal 18 Negative electrode terminal 19 Negative electrode plate 20 Negative electrode lead 21 Positive electrode 22 Positive electrode lead 23 Case 24 Insulating plate 25 Gasket 26 Safety valve 27 PTC element

Claims (14)

A non-aqueous electrolyte composition obtained by dissolving an electrolyte salt in an organic solvent, wherein the organic solvent is an organic solvent containing a glycol ether compound represented by the following general formula (1). Water electrolyte composition.

The non-aqueous electrolyte composition according to claim 1, wherein, in the general formula (1), R is an ethylene group, and X _{1 to} X ₁₀ are each independently a fluorine atom or a hydrogen atom. The general formula (1), wherein X ₁ , X ₃ , X ₈ and X ₁₀ are fluorine atoms, and X ₂ , X ₄ , X ₅ , X ₆ , X ₇ and X ₉ are hydrogen atoms. The non-aqueous electrolyte composition described. The general formula (1), wherein X ₂ , X ₄ , X ₇ and X ₉ are fluorine atoms, and X ₁ , X ₃ , X ₅ , X ₆ , X ₈ and X ₁₀ are hydrogen atoms. The non-aqueous electrolyte composition described. The general formula (1), wherein X ₁ , X ₅ , X ₆ and X ₁₀ are fluorine atoms, and X ₂ , X ₃ , X ₄ , X ₇ , X ₈ and X ₉ are hydrogen atoms. The non-aqueous electrolyte composition described. The general formula (1), wherein X ₁ , X ₃ , X ₅ , X ₆ , X ₈ and X ₁₀ are fluorine atoms, and X ₂ , X ₄ , X ₇ and X ₉ are hydrogen atoms. The non-aqueous electrolyte composition described. 2. The non-aqueous electrolyte composition according to claim 1, wherein, in the general formula (1), R is a trimethylene group, and X _{1 to} X ₁₀ are each independently a fluorine atom or a hydrogen atom. In the above general formula (1), X ₂ , X ₄ , X ₇ and X ₉ are fluorine atoms, and X ₁ , X ₃ , X ₅ , X ₆ , X ₈ and X ₁₀ are hydrogen atoms. 8. The non-aqueous electrolyte composition according to 7. In the general formula (1), X ₁ , X ₃ , X ₈ and X ₁₀ are fluorine atoms, and X ₂ , X ₄ , X ₅ , X ₆ , X ₇ and X ₉ are hydrogen atoms. 8. The non-aqueous electrolyte composition according to 7.   The nonaqueous electrolyte composition according to any one of claims 1 to 9, wherein the organic solvent contains one or more selected from the group of nonaqueous solvents consisting of carbonates, lactones, ethers, sulfolanes, and dioxolanes. object.   The non-aqueous electrolyte composition according to any one of claims 1 to 10, wherein the organic solvent contains at least one cyclic carbonate compound and a chain carbonate compound. The electrolyte salt is an inorganic salt composed of lithium ions and an anion selected from PF ₆ , BF ₄ , ClO ₄ and AsF ₆ , and lithium ions and CF ₃ SO ₃ , N (CF ₃ SO ₂ ) _2. The non-aqueous electrolyte composition according to claim 1, which is at least one selected from the group consisting of organic salts composed of C, CF (SO ₃ SO ₂ ) ₃ or derivatives thereof.   The glycol ether compound represented by the general formula (1) is contained in an amount of 0.5 to 60 parts by mass with respect to 100 parts by mass of an electrolytic solution obtained by dissolving an electrolyte salt in an organic solvent. The non-aqueous electrolyte composition described in 1. A non-aqueous electrolyte secondary battery comprising the non-aqueous electrolyte composition according to claim 1 as an electrolyte.

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