JP2006134817A - Electrolyte composition and battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrolyte composition having excellent ion conductivity and an excellent electrochemical characteristic. <P>SOLUTION: This electrolyte composition comprises: (A) at least either of (1) a polymer having ether binding and (2) a low-molecular ether compound having an ethylene oxide unit; and (B) a lithium methide salt compound. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electrolyte composition comprising a lithium methide salt compound in a low molecular ether compound having an ether bond or an ethylene oxide unit, and particularly suitable as a material for electrochemical devices such as batteries, capacitors and sensors. Related to things.

  Conventionally, electrolytes constituting electrochemical devices such as batteries, capacitors, sensors, etc. have been made from electrolytes or polymer electrolytes containing gels from the viewpoint of ion conductivity. It has been pointed out that there is a risk of damage to the device due to leakage, and that the electrolytic solution reacts with the positive electrode and the negative electrode to deteriorate the electrochemical characteristics. In contrast, solid electrolytes such as inorganic crystalline substances, inorganic glasses, and organic polymer substances have been proposed. Organic polymer materials are generally excellent in processability and moldability, and the solid electrolyte obtained has flexibility and bending workability, and the progress has been made in terms of increasing the degree of freedom in the design of applied devices. Expected. However, the current state is that it is inferior to other materials in terms of ion conductivity.

  The discovery of ionic conductivity in ethylene oxide homopolymers and alkali metal ion systems has led to active research on polymer solid electrolytes. As a result, polyethers such as polyethylene oxide are considered most promising as a polymer matrix in terms of high mobility and solubility of metal cations. It is predicted that ion migration will occur in the amorphous part of the polymer, not in the crystalline part. Since then, copolymerization with various epoxides has been performed to reduce the crystallinity of polyethylene oxide. U.S. Pat. No. 4,818,644 discloses a solid electrolyte made of a copolymer of ethylene oxide and methyl glycidyl ether. However, none of the ionic conductivities were always satisfactory.

For this reason, an attempt to apply a specific alkali metal salt to a diethylene glycol methyl glycidyl ether-ethylene oxide crosslinked product and apply it to a polymer solid electrolyte has been proposed in JP-A-9-324114. No degree value has been obtained. In order to further improve the ionic conductivity, a solid polymer electrolyte containing an aprotic organic solvent or a branched polyethylene glycol derivative has been proposed in WO98 / 07772 including the present applicant. However, when lithium metal is used as an electrode for these electrolytes, the reaction with the lithium metal or dendrite is deposited on the surface of the lithium metal, the electrochemical characteristics are remarkably lowered.
U.S. Patent No. 4,818,644 JP-A-9-324114 WO98 / 07772

  An object of the present invention is to provide an electrolyte composition having excellent ion conductivity and electrochemical characteristics.

The present invention comprises (A) (1) a polymer having an ether bond, (2) at least one of a low-molecular ether compound having an ethylene oxide unit, and (B) a lithium metide salt compound, and the components (1) and (2) Provided is an electrolyte composition characterized in that at least one of them is present.
The present invention also provides a crosslinked electrolyte composition obtained by crosslinking a polymer having an ether bond described in (1).

  In addition, the present invention also provides a battery using the electrolyte composition.

  It has also been found that when the electrolyte composition of the present invention is used, a battery having excellent cycle characteristics and high energy density can be obtained.

  The electrolyte composition containing the component (1) of the present invention is excellent in processability, moldability, mechanical strength, flexibility, heat resistance, and the like. The electrolyte composition of the present invention has remarkably improved electrochemical characteristics for lithium metal. Therefore, application to electronic devices such as batteries (particularly secondary batteries), large-capacity capacitors, display elements such as electrochromic displays is expected.

［式中、R^１は炭素数 1〜6のアルキル基、フェニル基または -CH_２O-R^２を表し、R^２は炭素数 1〜6のアルキル基またはフェニル基または-(-CH_２-CH_２-O-)a-R^２’または-CH[CH_２-O-(-CH_２-CH_２-O-)b-R^２’]_２を表し、R^２’ は炭素数 1〜6のアルキル基、aおよびb は 0〜12の整数である。］

［式中、R^３は（ａ）反応性ケイ素基、（ｂ）メチルエポキシ基、（ｃ）エチレン性不飽和基または（ｄ）ハロゲン原子を有する反応性基を表す］ The electrolyte composition of the present invention contains at least one of a polymer (1) and a low molecular ether compound (2). The electrolyte composition may include both the polymer (1) and the low molecular weight ether compound (2).
The main chain of the polymer having an ether bond is a copolymer having a structural unit represented by the following formula (i) and a structural unit represented by the following formula (ii), A copolymer having a structural unit represented by the following formula (iii) and a crosslinkable structural unit, or the structural unit (i), the structural unit (ii), and the following formula (iii) It is preferable that it is a copolymer which has a crosslinkable structural unit represented by these. Furthermore, a random copolymer is preferred.

[Wherein, R ¹ represents an alkyl group having 1 to 6 carbon atoms, a phenyl group, or —CH ₂ OR ² , and R ² represents an alkyl group having 1 to 6 carbon atoms, a phenyl group, or — (— CH ₂ —CH ₂ -O-) aR ^{2 'or} _{-CH [CH 2 -O - (-} CH 2 -CH 2 -O-) bR 2'] represents _2, R ^{2 'is} an alkyl group having 1 to 6 carbon atoms, a and b is an integer from 0 to 12. ]

[Wherein R ³ represents (a) a reactive silicon group, (b) a methylepoxy group, (c) an ethylenically unsaturated group or (d) a reactive group having a halogen atom]

  The monomer constituting the structural unit (i) in the polymer (1) is ethylene oxide.

  Examples of the oxirane compound constituting the structural unit (ii) in the polymer (1) include an alkylene oxide and a glycidyl ether compound which may have a substituent. Specifically, oxirane compounds such as propylene oxide, methyl glycidyl ether, butyl glycidyl ether, styrene oxide, phenyl glycidyl ether, 1,2-epoxyhexane, ethylene glycol methyl glycidyl ether, diethylene glycol methyl glycidyl ether, triethylene glycol methyl glycidyl Examples include ether, 1,3-bis (2-methoxyethoxy) propane 2-glycidyl ether, and 1,3-bis [2- (2-methoxyethoxy) ethoxy] propane 2-glycidyl ether.

  The reactive functional group of the oxirane compound forming the crosslinkable structural unit (iii) in the polymer (1) is (a) a reactive silicon group, (b) a methylepoxy group, (c) an ethylenically unsaturated group, or (D) A halogen atom.

  Examples of oxirane compounds having a reactive silicon group (a) include 2-glycidoxyethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 4-glycidoxybutyl Methyltrimethoxysilane, 3- (1,2-epoxy) propyltrimethoxysilane, 4- (1,2-epoxy) butyltrimethoxysilane, 5- (1,2-epoxy) pentyltrimethoxysilane, 1- ( 3,4-epoxycyclohexyl) methylmethyldimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane and the like. Of these, 3-glycidoxypropyltrimethoxysilane and 3-glycidoxypropylmethyldimethoxysilane are particularly preferred.

  Examples of oxirane compounds having a methyl epoxy group (b) include 2,3-epoxypropyl-2 ′, 3′-epoxy-2′-methylpropyl ether, ethylene glycol-2,3-epoxypropyl-2 ′, 3 ′. -Epoxy-2'-methylpropyl ether and diethylene glycol-2,3-epoxypropyl-2 ', 3'-epoxy-2'-methylpropyl ether, 2-methyl-1,2,3,4-diepoxybutane 2-methyl-1,2,4,5-diepoxypentane, 2-methyl-1,2,5,6-diepoxyhexane, hydroquinone-2,3-epoxypropyl-2 ', 3'-epoxy- Examples include 2'-methylpropyl ether, catechol-2,3-epoxypropyl-2 ', 3'-epoxy-2'-methylpropyl ether, and the like.

  Among them, especially 2,3-epoxypropyl-2 ', 3'-epoxy-2'-methylpropyl ether and ethylene glycol-2,3-epoxypropyl-2', 3'-epoxy-2'-methylpropyl Ether is preferred.

Examples of oxirane compounds having an ethylenically unsaturated group (c) include allyl glycidyl ether, 4-vinylcyclohexyl glycidyl ether, α-terpinyl glycidyl ether, cyclohexenyl methyl glycidyl ether, p-vinylbenzyl glycidyl ether, allyl phenyl glycidyl ether. Ether, vinyl glycidyl ether, 3,4-epoxy-1-butene, 3,4-epoxy-1-pentene, 4,5-epoxy-2-pentene, 1,2-epoxy-5,9-cyclododecadiene, 3,4-epoxy-1-vinylcyclohexene, 1,2-epoxy-5-cyclooctene, glycidyl acrylate, glycidyl methacrylate, glycidyl sorbate, glycidyl cinnamate, glycidyl crotonic acid, glycidyl-4-hexenoate It is done.
Preferably, allyl glycidyl ether, glycidyl acrylate, and glycidyl methacrylate are used.

  Examples of the oxirane compound having a halogen atom (d) include epibromohydrin, epiiodohydrin, epichlorohydrin and the like.

  The polymerization method of a polymer having an ether bond is a polymerization method for obtaining a copolymer by a ring-opening reaction of an ethylene oxide moiety, and the method described in JP-A-63-154736 and JP-A-62-169823 The same is done.

  The polymerization reaction can be performed as follows. Using a catalyst system mainly composed of organoaluminum, a catalyst system composed mainly of organic zinc, or an organotin-phosphate ester condensate catalyst system as a ring-opening polymerization catalyst, each monomer is present in the presence or absence of a solvent. The polyether copolymer is obtained by reacting under stirring at a reaction temperature of 10 to 80 ° C. Of these, an organotin-phosphate ester condensate catalyst system is particularly preferred from the viewpoint of the degree of polymerization or the properties of the copolymer to be produced. In the polymerization reaction, the reactive functional group does not react, and the polymer (1) having the reactive functional group is obtained.

  The proportion of ethylene oxide constituting the structural unit (i) is 10 to 95% by weight, preferably 20 to 90% by weight, for example 25 to 80% by weight, based on the polymer having an ether bond used in the electrolyte composition of the present invention. The amount of the oxirane compound constituting the structural unit (ii) is 90 to 5% by weight, preferably 80 to 10% by weight, for example 70 to 15% by weight. The oxirane compound constituting the crosslinkable structural unit (iii) is 0 -30% by weight, preferably 0-20% by weight, for example 1-15% by weight.

  When the amount of the oxirane compound constituting the crosslinkable structural unit (iii) is 30% by weight or less, the crosslinked polymer has good ionic conductivity.

When the amount of ethylene oxide constituting the structural unit (i) is 10% by weight or more, the lithium salt compound is easily dissolved even at a low temperature, so that the ionic conductivity is high.
In general, polymer electrolytes are known to improve ion conductivity by lowering the glass transition temperature. However, in the case of an electrolyte composition containing the polymer (1) having an ether bond of the present invention, the effect of improving ion conductivity. Was found to be much larger.

The molecular weight of the polymer used in the electrolyte composition is within the range of a weight average molecular weight of 10 ⁴ to 10 ⁸ , preferably 10 ⁵ to 10 ⁷ in order to obtain good processability, moldability, mechanical strength and flexibility. Those within range are suitable.

  As a crosslinking method of the polymer (1) whose reactive functional group is the reactive silicon group (a), crosslinking can be performed by reaction of the reactive silicon group with water. To increase reactivity, tin compounds such as dibutyltin dilaurate and dibutyltin malate, titanium compounds such as tetrabutyl titanate and tetrapropyl titanate, aluminum compounds such as aluminum such as aluminum trisacetylacetonate and aluminum trisethylacetoacetate, etc. An organometallic compound or an amine compound such as butylamine or octylamine may be used as a catalyst.

In the crosslinking method of the polymer (1) in which the reactive functional group is a methyl epoxy group (b), polyamines, acid anhydrides and the like are used.
Examples of polyamines include aliphatic polyamines such as diethylenetriamine and dipropylenetriamine, and aromatic polyamines such as 4,4′-diaminodiphenyl ether, diaminodiphenylsulfone, m-phenylenediamine, and xylylenediamine. The amount of polyamine added varies depending on the type of polyamine, but is usually in the range of 0.1 to 10 parts by weight per 100 parts by weight of polymer (1).

  Examples of the acid anhydrides include maleic anhydride, phthalic anhydride, methylhexahydrophthalic anhydride, tetramethylene maleic anhydride, tetrahydrophthalic anhydride and the like. The amount of acid anhydride added varies depending on the type of acid anhydride, but is usually in the range of 0.1 to 10 parts by weight per 100 parts by weight of the polymer (1). Accelerators may be used for these crosslinks, such as phenol, cresol, and resorcin for polyamine cross-linking reactions, and benzyldimethylamine and 2- (dimethylaminoethyl) phenol for cross-linking reactions of acid anhydrides. And dimethylaniline. The addition amount of the accelerator varies depending on the accelerator, but is usually in the range of 0.1 to 10 parts by weight per 100 parts by weight of the crosslinking agent.

  Examples of the crosslinking method of the polymer (1) in which the reactive functional group is an ethylenically unsaturated group (c) include radical initiators selected from organic peroxides, azo compounds, and the like, and active energy rays such as ultraviolet rays and electron beams. Used. Furthermore, a crosslinking agent having silicon hydride can also be used.

  Examples of organic peroxides include ketone peroxides, peroxyketals, hydroperoxides, dialkyl peroxides, diacyl peroxides, peroxydicarbonates, peroxyesters, and the like that are usually used for crosslinking. 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane, di-t-butyl peroxide, t-butylcumyl peroxide, dicumyl peroxide, 2,5-dimethyl-2, 5-di (t-butylperoxy) hexane, benzoyl peroxide, and the like. The amount of organic peroxide added varies depending on the type of organic peroxide, but is usually in the range of 0.1 to 10 parts by weight per 100 parts by weight of the polymer (1).

  As the azo compound, those usually used for crosslinking such as an azonitrile compound, an azoamide compound, an azoamidine compound, etc. are used. 2,2′-azobisisobutyronitrile, 2,2′-azobis (2-methylbutyrate) Nitrile), 2,2'-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2,2-azobis (2-methyl-N-phenylpropionamidine) dihydrochloride, 2,2'-azobis [2- (2-imidazolin-2-yl) propane], 2,2'-azobis [2-methyl-N- (2-hydroxyethyl) propionamide], 2,2'-azobis (2-methylpropane) 2,2′-azobis [2- (hydroxymethyl) propionitrile] and the like. Although the addition amount of an azo compound changes with kinds of azo compound, it is in the range of 0.1-10 weight part normally with respect to 100 weight part of polymers (1).

  In crosslinking by irradiation with active energy rays such as ultraviolet rays, glycidyl acrylate, glycidyl methacrylate, and glycidyl cinnamate are particularly preferable. Further, as sensitization aids, diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, acetophenones such as phenyl ketone, benzoin ethers such as benzoin and benzoin methyl ether, benzophenone, 4- Benzophenones such as phenylbenzophenone, thioxanthones such as 2-isopropylthioxanthone and 2,4-dimethylthioxanthone, and azides such as 3-sulfonyl azidobenzoic acid and 4-sulfonylazidebenzoic acid can be arbitrarily used.

  Crosslinking aids such as ethylene glycol diacrylate, ethylene glycol dimethacrylate, oligoethylene glycol diacrylate, oligoethylene glycol dimethacrylate, allyl methacrylate, allyl acrylate, diallyl malate, triallyl isocyanurate, bisphenylmaleimide, maleic anhydride, etc. Can be used arbitrarily.

  As the compound having silicon hydride for crosslinking the ethylenically unsaturated group (c), a compound having at least two silicon hydrides is used. In particular, a polysiloxane compound or a polysilane compound is preferable.

  Examples of the hydrosilylation reaction catalyst include transition metals such as palladium and platinum, or compounds and complexes thereof. In addition, peroxides, amines, and phosphines are also used. The most common catalysts include dichlorobis (acetonitrile) palladium (II), chlorotris (triphenylphosphine) rhodium (I), and chloroplatinic acid.

  As a method for crosslinking the polymer (1) having an ether bond whose reactive functional group is a halogen atom (d), a crosslinking agent such as polyamines, mercaptoimidazolines, mercaptopyrimidines, thioureas, and polymercaptans is used. . Examples of polyamines include triethylenetetramine and hexamethylenediamine. Examples of mercaptoimidazolines include 2-mercaptoimidazoline and 4-methyl-2-mercaptoimidazoline. Examples of mercaptopyrimidines include 2-mercaptopyrimidine, 4,6-dimethyl-2-mercaptopyrimidine, and the like. Examples of thioureas include ethylene thiourea and dibutyl thiourea. Examples of the polymercaptans include 2-dibutylamino-4,6-dimethylcapto-s-triazine, 2-phenylamino-4,6-dimercaptotriazine, and the like. Although the addition amount of a crosslinking agent changes with kinds of crosslinking agent, it is 0.1-30 weight part normally with respect to 100 weight part of polymers (1).

  In addition, it is effective from the viewpoint of the thermal stability of the halogen-containing polymer to add a metal compound serving as an acid acceptor to the electrolyte composition. Examples of metal oxides that serve as such acid acceptors include Group II metal oxides, hydroxides, carbonates, carboxylates, silicates, borates, phosphites, periodic Table VIa group metal oxides, basic carbonates, basic carboxylates, basic phosphites, basic sulfites, tribasic sulfates, and the like. Specific examples include magnesia, magnesium hydroxide, magnesium carbonate, calcium silicate, calcium stearate, red lead, tin stearate, and the like. The amount of the metal compound serving as the acid acceptor varies depending on the type, but is usually in the range of 0.1 to 30 parts by weight with respect to 100 parts by weight of the polymer (1).

  The low molecular ether compound (2) having an ethylene oxide unit functions as a plasticizer when used in combination with the polymer (1). When the low molecular weight ether compound (2) having an ethylene oxide unit is added to the polymer electrolyte composition, the crystallization of the polymer is suppressed, the glass transition temperature is lowered, and a large number of amorphous phases are formed even at a low temperature. Get higher.

[式中、R^４〜R^１８ は、炭素数 1〜6のアルキル基、c〜r は 0〜12の数である。] The low molecular ether compound (2) containing an ether compound having an ethylene oxide unit is preferably an ether compound having a molecular weight of 3000 or less. Preferred examples of the molecular structure of the low molecular ether compound are preferably low molecular ether compounds represented by any of the following formulas (iv) to (vii).

[Wherein, R ^{4 to} R ¹⁸ are alkyl groups having 1 to 6 carbon atoms, and c to r are 0 to 12 numbers. ]

[式中、R^１９ は SO_２C_ｎF_２ｎ＋１ または C_ｎH_２ｎ＋１, n は 1〜5 の整数である。]
リチウムメチド化合物の具体例としては、リチウムトリス（トリフルオロメタンスルホニル）メチド、リチウムトリス（ペンタフルオロエタンスルホニル）メチドが挙げられる。
また、他のリチウム塩化合物と併用することもできる。他のリチウム塩化合物としては、陽イオンのリチウムイオンと、塩素イオン、臭素イオン、ヨウ素イオン、過塩素酸イオン、チオシアン酸イオン、テトラフルオロホウ素酸イオン、硝酸イオン、AsF_６ ⁻、PF_６ ⁻、ステアリルスルホン酸イオン、オクチルスルホン酸イオン、ドデシルベンゼンスルホン酸イオン、ナフタレンスルホン酸イオン、ドデシルナフタレンスルホン酸イオン、7,7,8,8-テトラシアノ-ｐ-キノジメタンイオン、X^１SO_３ ⁻、[(X^１ＳＯ_２)(X^２SO_２)N]⁻から選ばれた陰イオンとからなる化合物が挙げられる。但し、X^１、X^２及び Yは電子吸引性基である。好ましくはX^１及びX^２は各々独立して炭素数が１から６迄のパーフルオロアルキル基又はパーフルオロアリール基であり、Ｙはニトロ基、ニトロソ基、カルボニル基、カルボキシル基又はシアノ基である。X^１及びX²は各々同一であっても、異なっていてもよい。 The lithium methide salt compound (B) used in the present invention comprises the component (A) constituting the electrolyte composition, that is, the polymer (1), the low molecular ether compound (2), or the polymer (1) and the low molecular ether compound (2 It is preferably soluble in the mixture of Examples of the lithium methide compound are preferably those represented by the following formula (viii).

[Wherein R ¹⁹ is SO ₂ C _n F _{2n + 1} or C _n H _{2n + 1} , n is an integer of 1 to 5. ]
Specific examples of the lithium methide compound include lithium tris (trifluoromethanesulfonyl) methide and lithium tris (pentafluoroethanesulfonyl) methide.
Moreover, it can also use together with another lithium salt compound. Other lithium salt compounds include cation lithium ions, chlorine ions, bromine ions, iodine ions, perchlorate ions, thiocyanate ions, tetrafluoroborate ions, nitrate ions, AsF ₆ ⁻ , PF ₆ ⁻ , Stearyl sulfonate ion, octyl sulfonate ion, dodecylbenzene sulfonate ion, naphthalene sulfonate ion, dodecyl naphthalene sulfonate ion, 7,7,8,8-tetracyano-p-quinodimethane ion, X ¹ SO ₃ ⁻ , And a compound comprising an anion selected from [(X ¹ SO ₂ ) (X ² SO ₂ ) N] ⁻ . However, X ¹ , X ² and Y are electron withdrawing groups. Preferably X ¹ and X ² are each independently a perfluoroalkyl group or a perfluoroaryl group having 1 to 6 carbon atoms, and Y is a nitro group, a nitroso group, a carbonyl group, a carboxyl group or a cyano group. . X ¹ and X ² may be the same or different.

  In the present invention, the total amount used with the lithium metide salt compound (B) or other lithium salt compound is (A), that is, the polymer (1), the low molecular weight ether compound (2), or (1) and ( The range of 1 to 500 parts by weight, preferably 3 to 300 parts by weight, based on the total 100 parts by weight of 2). When this value is 500 parts by weight or less, when the electrolyte composition contains the polymer (1), the workability, the moldability, the mechanical strength and flexibility of the obtained electrolyte are high, and the ionic conductivity is also high. . The amount of the other lithium salt compound to be used is in the range of 0 to 100,000 parts by weight, preferably 0 to 10,000 parts by weight, for example 1 to 2,000 parts by weight, based on 100 parts by weight of the lithium metide salt compound (B).

  A flame retardant can be used when a flame retardance is required when using an electrolyte composition. Flame retardants include brominated epoxy compounds, tetrabrombisphenol A, halides such as chlorinated paraffin, antimony trioxide, antimony pentoxide, aluminum hydroxide, magnesium hydroxide, phosphate ester, polyphosphate, and zinc borate Select from and add an effective amount.

  A stabilizer can be used in combination when stability with lithium metal is required when the electrolyte composition is used. An effective amount of a cyclic carbonate having an unsaturated group such as vinylene carbonate or vinyl ethylene carbonate is added as a stabilizer.

  In the case of a lithium metal battery, the lithium methide salt (B) is stable to the metal lithium of the negative electrode, and suppresses dendrite growth of lithium.

  Although there is no restriction | limiting in particular in the manufacturing method of the electrolyte composition of this invention, Usually, what is necessary is just to mix each component mechanically. When the polymer (1) is used as the component (A) constituting the electrolyte composition, various kneaders, open rolls, extruders, and the like can be arbitrarily used. In the case of the polymer (1) requiring cross-linking, it is produced by a method such as cross-linking after mechanically mixing the respective components. After crosslinking, the low molecular weight ether compound (2) may be immersed for a long time to be impregnated.

  The method for mixing the lithium methide salt compound (B) and the low molecular weight ether compound (2) with the polymer (1) is not particularly limited, but the polymer (1 ) For a long time soaking and impregnation, a method of mechanically mixing the lithium methide salt (B) and the low molecular weight ether compound (2) into the polymer (1), a low molecular weight of the polymer (1) and the lithium methide salt (B) There are a method in which the ether compound (2) is dissolved and mixed, or a method in which the polymer (1) is once dissolved in another organic solvent and then the low molecular ether compound (2) is mixed. When producing using an organic solvent, various polar solvents such as tetrahydrofuran, acetone, acetonitrile, dimethylformamide, dimethyl sulfoxide, dioxane, methyl ethyl ketone, methyl isobutyl ketone and the like are used alone or in combination.

  The electrolyte composition shown in the present invention has a low vapor pressure, and in particular, the crosslinked electrolyte composition is excellent in mechanical strength and flexibility. Is easily obtained. For example, it is possible to produce a battery using the electrolyte composition of the present invention. In this case, the positive electrode material may be any positive electrode material capable of inserting and extracting lithium, and a lithium-containing compound such as lithium oxide, lithium sulfide, or an intercalation compound containing lithium is suitable. Specifically, lithium-manganese composite oxide, lithium cobaltate, lithium nickelate, vanadium pentoxide, olivine-type iron phosphate, polyacetylene, polypyrene, polyaniline, polyphenylene, polyphenylene sulfide, polyphenylene oxide, polypyrrole, polyfuran, polyazulene, etc. is there. Lithium metal can be used as the negative electrode material. The negative electrode material may be any negative electrode material capable of inserting and extracting lithium, and may be a carbon material, a metal element or a metalloid element or compound capable of forming an alloy with lithium, another metal compound or High molecular compounds are suitable. Specific examples of the carbon material include graphite, non-graphitizable carbon, and graphitizable carbon. Specific examples of the metal element or metalloid element capable of forming an alloy with lithium include tin, aluminum, lead, indium, silicon, zinc, magnesium, boron, gallium, and germanium. Specific examples of other metal compounds include iron oxide, ruthenium oxide, molybdenum oxide and the like. Specific examples of the polymer compound include polyacetylene, polyaniline, and polypyrrole. Moreover, utilization as a diaphragm of an ion electrode of cations, such as an alkali metal ion, Cu ion, Ca ion, and Mg ion, is also considered using high ion conductivity. The electrolyte composition of the present invention is particularly suitable as a material for electrochemical devices such as batteries, capacitors and sensors.

  Hereinafter, the present invention will be specifically described with reference to examples. In addition, the electrolyte composition and the secondary battery in the present invention are not limited to those shown in the following examples, and can be appropriately modified and implemented without departing from the scope of the invention.

The monomer equivalent composition of the polymer (1) having an ether bond was determined by ¹ H NMR spectrum. For measuring the molecular weight of the polymer having an ether bond, gel permeation chromatography was performed, and the molecular weight was calculated in terms of standard polystyrene. Gel permeation chromatography measurement was performed by Shimadzu Corporation RID-6A, Showa Denko Co., Ltd. columns Shodex KD-807, KD-806, KD-806M and KD-803, and solvent dimethylformamide ( DMF) at 60 ° C. The glass transition temperature is DSC 220 manufactured by Seiko Denshi Kogyo Co., Ltd., and the heat of fusion is DSC 7 differential scanning calorimeter manufactured by PerkinElmer. Measured in min. The conductivity was measured by a complex impedance method using an electrode made of SUS, placing the cell in a thermostat at 10 ° C., and using an AC method with an applied voltage of 30 mV and a frequency range of 10 Hz to 10 MHz.
In order to evaluate the stability of the lithium metal and the electrolyte composition of the present invention, a lithium precipitation dissolution efficiency test was conducted. A charge / discharge tester BTS-2004W manufactured by Nagano Co., Ltd. was used for the lithium precipitation dissolution efficiency test. A test cell was prepared by using metallic lithium for the copper foil and the counter electrode and sandwiching the electrolyte composition between the two electrodes. After 10 hours lithium at a current density of 0.1 mA / cm ² is deposited on the copper electrode, operation was repeated for dissolving lithium to a final voltage 2.0V at a current density of 0.1 mA / cm ^2. The lithium precipitation dissolution efficiency was determined from the following equation.
Lithium precipitation dissolution efficiency (%) = (time required for dissolution in n cycle / time required for precipitation in n cycle) × 100

Synthesis example (catalyst production)
In a three-necked flask equipped with a stirrer, thermometer and distillation device, add 10 g of tributyltin chloride and 35 g of tributyl phosphate and heat at 250 ° C. for 20 minutes with stirring under a nitrogen stream to distill off the distillate. As a product, a solid condensate was obtained. Thereafter, this was used as a polymerization catalyst.

Polymerization Example 1 (Production of polymer)
The inside of a glass 4-necked flask with an internal volume of 3 L was purged with nitrogen, 2 g of the condensate shown in the catalyst production example as a catalyst, 60 g of glycidyl methacrylate adjusted to a water content of 10 ppm or less, and n-hexane 1,000 g as a solvent Then, 195 g of ethylene oxide was sequentially added while monitoring the polymerization rate of glycidyl methacrylate by gas chromatography. The polymerization reaction was stopped with methanol. The polymer was taken out by decantation and then dried at 40 ° C. under normal pressure for 24 hours and further under reduced pressure at 45 ° C. for 10 hours to obtain 207 g of polymer. This copolymer had a glass transition temperature of -62 ° C, a weight average molecular weight of 1,200,000, and a heat of fusion of 65 J / g. As a result of analyzing the composition in terms of monomer of the copolymer by ¹ H NMR spectrum, ethylene oxide was 80 wt% and glycidyl methacrylate was 20 wt%.

Polymerization Example 2 (Production of polymer)
The inside of a glass 4-necked flask with an internal volume of 3 L was purged with nitrogen, and as a catalyst, 2 g of the condensate shown in the catalyst production example, 100 g of propylene oxide adjusted to a water content of 10 ppm or less, 10 g of glycidyl methacrylate and n as a solvent -1,000 g of hexane was charged, and 200 g of ethylene oxide was sequentially added while monitoring the polymerization rate of propylene oxide by gas chromatography. The polymerization reaction was stopped with methanol. The polymer was taken out by decantation and then dried at 40 ° C. under normal pressure for 24 hours and further at 45 ° C. for 10 hours under reduced pressure to obtain 283 g of polymer. This copolymer had a glass transition temperature of −68 ° C., a weight average molecular weight of 1.7 million, and a heat of fusion of 7 J / g. As a result of analyzing the composition of the copolymer in terms of monomers by ¹ H NMR spectrum, ethylene oxide was 67 wt%, propylene oxide was 30 wt%, and glycidyl methacrylate was 3 wt%.

Polymerization Example 3 (Production of polymer)
The inside of a 3L glass four-necked flask with nitrogen content was replaced with nitrogen, and as a catalyst, 2g of the condensate shown in the catalyst production example and 100g of oxirane compound (GM) of formula (x) Then, 10 g of allyl glycidyl ether and 1,000 g of n-hexane were charged, and 120 g of ethylene oxide was sequentially added while monitoring the polymerization rate of GM by gas chromatography. The polymerization reaction was stopped with methanol. The polymer was taken out by decantation and then dried at 40 ° C. under normal pressure for 24 hours and further at 45 ° C. for 10 hours under reduced pressure to obtain 205 g of polymer. This copolymer had a glass transition temperature of -74 ° C., a weight average molecular weight of 1.15 million, and a heat of fusion of 3 J / g. As a result of monomer composition analysis of this copolymer by ¹ H NMR spectrum, ethylene oxide was 53 wt%, GM was 43 wt%, and allyl glycidyl ether was 4 wt%.

Polymerization Example 4 (Production of polymer)
The inside of a glass 4-necked flask with an internal volume of 3 L is purged with nitrogen, and as a catalyst, 2 g of the condensate shown in the catalyst production example and 180 g of oxirane compound (EM) of the following formula (ix) adjusted to a water content of 10 ppm or less Then, 20 g of allyl glycidyl ether and 1,000 g of n-hexane were charged, and 120 g of ethylene oxide was sequentially added while monitoring the polymerization rate of EM by gas chromatography. The polymerization reaction was stopped with methanol. The polymer was taken out by decantation and then dried at 40 ° C. under normal pressure for 24 hours and further under reduced pressure at 45 ° C. for 10 hours to obtain 298 g of polymer. This copolymer had a glass transition temperature of −72 ° C., a weight average molecular weight of 1.3 million, and a heat of fusion of 3 J / g. ^The results of analyzing the composition of this copolymer in terms of monomer by ¹ H NMR spectrum were ethylene oxide 37 wt%, EM 57 wt%, and allyl glycidyl ether 6 wt%.

Example 1
An electrolyte composition was obtained by mixing 3 g of a low molecular weight ether compound having an ethylene oxide unit of the following formula (vii-1) and 1.7 g of lithium tris (trifluoromethanesulfonyl) methide as a lithium salt compound until uniform. The ionic conductivity was 1.8 × 10 ⁻⁴ S / cm, and the average value of the lithium precipitation dissolution efficiency was 93%. The results are shown in Table 1.

Example 2
An electrolyte composition was obtained by mixing 3 g of a low molecular weight ether compound having an ethylene oxide unit of the following formula (iv-1) and 1.7 g of lithium tris (trifluoromethanesulfonyl) methide as a lithium salt compound until uniform. The ionic conductivity was 2.4 × 10 ⁻⁴ S / cm, and the average lithium precipitation dissolution efficiency was 95%. The results are shown in Table 1.

Example 3
An electrolyte composition was obtained by mixing 3 g of a low molecular weight ether compound having an ethylene oxide unit of the following formula (iv-2) and 1.7 g of lithium tris (trifluoromethanesulfonyl) methide as a lithium salt compound until uniform. The ionic conductivity was 3.6 × 10 ⁻⁴ S / cm, and the average value of the lithium precipitation dissolution efficiency was 96%. The results are shown in Table 1.

Comparative Example 1
An electrolyte composition was obtained by mixing 3 g of a low molecular weight ether compound having an ethylene oxide unit of the above formula (vii-1) and 1.2 g of lithium bis (trifluoromethanesulfonyl) imide (LiTFSI) as a lithium salt compound until uniform. The ionic conductivity was 3.2 × 10 ⁻⁴ S / cm, and the average lithium precipitation dissolution efficiency was 58%. The results are shown in Table 1.

Comparative Example 2
An electrolyte composition was obtained by mixing 3 g of a low molecular weight ether compound having an ethylene oxide unit of the above formula (iv-1) and 0.3 g of lithium borofluoride (LiBF ₄ ) as a lithium salt compound until uniform. The ionic conductivity was 2.1 × 10 ⁻⁴ S / cm, and the average value of the lithium precipitation dissolution efficiency was 32%. The results are shown in Table 1.

Comparative Example 3
An electrolyte composition was obtained by mixing 3 g of a low molecular weight ether compound having an ethylene oxide unit of the above formula (iv-2) and 0.3 g of lithium perchlorate (LiClO ₄ ) as a lithium salt compound until uniform. The ionic conductivity was 3.2 × 10 ⁻⁴ S / cm, and the average value of the lithium precipitation dissolution efficiency was 30%. The results are shown in Table 1.

Example 4
1 g of an ethylene oxide / glycidyl methacrylate binary copolymer having a weight average molecular weight of 1.2 million obtained in Polymerization Example 1, 5 g of a low molecular weight ether compound having an ethylene oxide unit of the above formula (vii-1), and lithium as a lithium salt compound After mixing 3.4 g of tris (trifluoromethanesulfonyl) methide in 20 g of acetonitrile until it is uniform, it was coated on both sides of a 16 μm thick porous membrane (E16 manufactured by Tonen Chemical Co., Ltd.) and then dried under reduced pressure at 30 ° C. for 12 hours. A 37 μm electrolyte film was obtained. The average lithium precipitation dissolution efficiency was 95%. The results are shown in Table 1.

Comparative Example 4
An electrolyte film of 32 μm was obtained in the same manner using 2.4 g of lithium bis (trifluoromethylsulfonyl) imide (LiTFSI) instead of lithium tris (trifluoromethanesulfonyl) methide in Example 4. The average lithium precipitation dissolution efficiency was 62%. The results are shown in Table 1.

Example 5
1 g of ethylene oxide / propylene oxide / glycidyl methacrylate terpolymer having a weight average molecular weight of 1.7 million obtained in Polymerization Example 2, 2 g of a low molecular weight ether compound having an ethylene oxide unit of the above formula (iv-1), lithium salt After mixing 1.7 g of lithium tris (trifluoromethanesulfonyl) methide as a compound, 0.015 g of benzoyl peroxide as an initiator, and 0.3 g of ethylene glycol diacrylate as a crosslinking aid in 27 g of acetonitrile until homogeneous, a polyethylene terephthalate resin ( PET) film was uniformly applied. Thereafter, it was dried under reduced pressure at 30 ° C. for 12 hours, and further heated at 100 ° C. for 3 hours in a nitrogen atmosphere to obtain a 50 μm crosslinked electrolyte film. The ionic conductivity was 1.1 × 10 ⁻⁴ S / cm, and the average value of the lithium precipitation dissolution efficiency was 94%. The results are shown in Table 1.

Comparative Example 5
A 45 μm electrolyte film was obtained in the same manner by replacing lithium tris (trifluoromethanesulfonyl) methide in Example 5 with 0.3 g of lithium borofluoride (LiBF 4). The ionic conductivity was 9.3 × 10 ⁻⁵ S / cm, and the average value of the lithium precipitation dissolution efficiency was 35%. The results are shown in Table 1.

Example 6
1 g of ethylene oxide / GM / allyl glycidyl ether terpolymer having a weight average molecular weight of 1.15 million obtained in Polymerization Example 3, 2 g of a low molecular ether compound having an ethylene oxide unit of the above formula (iv-2), lithium salt compound Lithium bis (perfluoroethylsulfonyl) imide (LiBETI) 1.4 g, lithium tris (trifluoromethanesulfonyl) methide 0.17 g, benzoyl peroxide 0.015 g as an initiator, ethylene glycol diacrylate 0.3 g as a crosslinking aid in 50 g of acetonitrile Was mixed until uniform, and then uniformly applied to a PET film. Thereafter, it was dried under reduced pressure at 30 ° C. for 12 hours, and further heated at 100 ° C. for 3 hours in a nitrogen atmosphere to obtain a 50 μm crosslinked electrolyte film. The average value of the lithium precipitation dissolution efficiency was 94%. The results are shown in Table 1.

Comparative Example 6
A lithium salt of Example 6 was replaced with 1.6 g of lithium bis (perfluoroethylsulfonyl) imide (LiBETI), and a 60 μm electrolyte film was obtained in the same manner. The average value of the lithium precipitation dissolution efficiency was 77%. The results are shown in Table 1.

Example 7
3 g of ethylene oxide / EM / allyl glycidyl ether terpolymer having a weight average molecular weight of 1.3 million obtained in Polymerization Example 4, 1.7 g of lithium tris (trifluoromethanesulfonyl) methide as a lithium salt compound, and benzoyl peroxide as an initiator 0.015 g and 0.15 g of ethylene glycol dimethacrylate as a crosslinking aid were mixed in 50 g of acetonitrile until uniform, and then uniformly applied to a PET film. Thereafter, it was dried under reduced pressure at 30 ° C. for 12 hours, and further heated at 100 ° C. for 3 hours in a nitrogen atmosphere to obtain a 50 μm crosslinked electrolyte film. The ionic conductivity was 4.2 × 10 ⁻⁶ S / cm, and the average lithium precipitation dissolution efficiency was 97%. The results are shown in Table 1.

Comparative Example 7
The lithium tris (trifluoromethanesulfonyl) methide of Example 7 was replaced with 0.3 g of lithium perchlorate (LiClO ₄ ) to obtain a 43 μm electrolyte film in the same manner. The ionic conductivity was 2.8 × 10 ⁻⁶ S / cm, and the average value of the lithium precipitation dissolution efficiency was 29%. The results are shown in Table 1.

Production example 1 of positive electrode
90 g of lithium cobaltate powder (Honjo FMC Energy Systems), 4 g of acetylene black (Denka Black manufactured by Denki Kagaku Kogyo Co., Ltd.), 6 g of polyvinylidene fluoride (SOLEF 1015 manufactured by SOLVAY SOLEXIS), and 100 g of dimethylformamide were mixed using a disper. Then, after coating on an aluminum foil (thickness 25 μm), the solvent was removed by drying under reduced pressure. After pressing using two rolls, it was cut into a disk shape with a diameter of 14 mm. The cut electrode was dried by heating to 120 ° C. under reduced pressure and stored in a glove box under an argon atmosphere.

Production example 2 of positive electrode
83 g of lithium cobaltate powder (Honjo FMC Energy Systems), 5 g of acetylene black (Denka Black manufactured by Denki Kagaku Kogyo Co., Ltd.), 12 g of the ethylene oxide / EM / allyl glycidyl ether terpolymer obtained in Polymerization Example 4 and lithium tris 6.8 g of (trifluoromethanesulfonyl) methide was added, mixed in acetonitrile dispersion for 2 hours, applied as a paste uniformly on aluminum foil, dried at 100 ° C. for 2 hours, and then rolled with a press machine (Chibi manufactured by Sunk Co., Ltd.). (Roll press). After cutting into a disk shape having a diameter of 14 mm, the cut electrode was dried by heating to 80 ° C. under reduced pressure and stored in a glove box in an argon atmosphere.

Production Example 3 of positive electrode
A positive electrode was produced in the same manner as in Production Example 2 of the positive electrode using 1.5 g of lithium borofluoride instead of lithium tris (trifluoromethanesulfonyl) methide in Production Example 2 of the positive electrode.

Example 8
A secondary battery in which an electrolyte composition obtained in Example 2, a lithium metal foil having a thickness of 30 μm as a negative electrode, a positive electrode prepared in Preparation Example 1 of a positive electrode, and a polyethylene microporous film having a thickness of 25 μm are arranged between the electrodes. Configured.
Charging was performed at a constant current of 0.1 mA / cm ² up to 4.2 V, and then until the current value decreased to 0.005 mA / cm ² at a constant voltage of 4.2 V. Discharging was performed at a constant current of 0.1 mA / cm ² up to 3V. The discharge capacity at the 50th cycle was 90% of the discharge capacity at the 5th cycle.

Comparative Example 8
A secondary battery was prepared in the same manner as in Example 8 except that the electrolyte composition obtained in Comparative Example 2 was used, and a charge / discharge test was performed.

Example 9
A secondary battery was configured using the electrolyte crosslinked film obtained in Example 5, a lithium metal foil having a thickness of 30 μm as the negative electrode, and the positive electrode prepared in Production Example 2 of the positive electrode.
Charging was carried out at a constant current of 0.1 mA / cm ² up to 4.2 V, and then at a constant voltage of 4.2 V until the current value dropped to 0.005 mA / cm ² . Discharging was performed at a constant current of 0.1 mA / cm ² up to 3V. The discharge capacity at the 50th cycle was 93% of the discharge capacity at the 5th cycle.

Comparative Example 9
A secondary battery was prepared in the same manner as in Example 9 except that the electrolyte crosslinked film obtained in Comparative Example 5 and the positive electrode prepared in Positive Electrode Preparation Example 3 were used. Short circuited.

The electrolyte composition of the present invention is excellent in lithium deposition dissolution efficiency, and the lithium battery using the electrolyte composition is excellent in cycle characteristics. Therefore, application to electronic devices such as batteries, large-capacity capacitors and display elements such as electrochromic displays, and application as antistatic agents for plastics are expected.

Claims (8)

(A) (1) a polymer having an ether bond;
(2) An electrolyte composition comprising at least one of a low-molecular ether compound having an ethylene oxide unit and (B) a lithium methide salt compound.   The electrolyte composition according to claim 1, wherein the polymer (1) having an ether bond is a polyether having an ethylene oxide unit. A copolymer in which the main chain of the polymer (1) having an ether bond has a structural unit represented by the following formula (i) and a structural unit represented by the following formula (ii); and / or A copolymer having a structural unit (i) and a crosslinkable structural unit represented by the following formula (iii) and / or the structural unit (i), the structural unit (ii), and the following formula (iii) The electrolyte composition according to claim 1, which is a copolymer having a crosslinkable structural unit.

[Wherein R ³ represents (a) a reactive silicon group, (b) a methylepoxy group, (c) an ethylenically unsaturated group or (d) a reactive group having a halogen atom] The electrolyte composition according to any one of claims 1 to 3, wherein the low molecular weight ether compound (2) having an ethylene oxide unit is a compound represented by any one of (iv) to (vii).

[Wherein, R ^{4 to} R ¹⁸ are alkyl groups having 1 to 6 carbon atoms, and c to r are 0 to 12 numbers. ] The electrolyte composition according to any one of claims 1 to 4, wherein the lithium metide salt compound (B) is represented by the following formula (viii).

[Wherein R ¹⁹ is SO ₂ C _n F _{2n + 1} or C _n H _{2n + 1} , n is an integer of 1 to 5. ]   The crosslinked electrolyte composition obtained by bridge | crosslinking the polymer (1) which has an ether bond in any one of Claims 1-5.   A battery comprising the electrolyte composition according to claim 1, a positive electrode, and a negative electrode. The battery according to claim 7, wherein the negative electrode is lithium metal.