JP4940285B2 - Electrolyte material - Google Patents

Abstract

An object of the present invention is to provide a material for an electrolytic solution having improved ionic conductivity and, showing excellent in low temperature property, being stable with time,and being electrochemically stable at a high potential, and an ionic material-containing composition exhibiting excellent fundamental performance such as electrochemical stability, and preferably usedin a variety of utilities. Another object of the present invention is to provide utilities thereof. The material for an electrolytic solution is the material containing an ionic compound, and the material comprises a cyano group-containing anion represented by the formula (1) and 1 to 99% by mass of a solvent in 100% by mass of the material for an electrolytic solution.

Description

  The present invention relates to an electrolyte material. More specifically, the present invention relates to an electrolytic solution material suitably used for an electrolytic solution that is an ionic conductor of an electrochemical device.

Electrolytic solution materials are widely used in various types of batteries using ion conduction. For example, in addition to batteries having charging and discharging mechanisms such as primary batteries, lithium (ion) secondary batteries and fuel cells, electrolysis It is used in electrochemical devices such as capacitors, electric double layer capacitors, solar cells, and electrochromic display elements. In these, a battery is generally composed of a pair of electrodes and an electrolytic solution which is an ionic conductor filling between the electrodes. Examples of such ionic conductors include organic solvents such as γ-butyrolactone, N, N-dimethylformamide, propylene carbonate, tetrahydrofuran, lithium perchlorate, LiPF ₆ , LiBF ₄ , tetraethylammonium borofluoride, tetramethyl phthalate. An electrolytic solution in which an electrolyte such as ammonium is dissolved is used. In such an ionic conductor, when the electrolyte is dissolved, it is dissociated into a cation and an anion to conduct ions in the electrolytic solution.

FIG. 1 shows a schematic cross-sectional view of one form of a general lithium (ion) secondary battery. Such a lithium (ion) secondary battery has a positive electrode and a negative electrode formed from an active substance, and an electrolyte solution composed of an organic solvent in which a lithium salt such as LiPF ₆ is dissolved as a solute, An ionic conductor is formed between the negative electrode. In this case, at the time of charging, a reaction of C ₆ Li → 6C + Li + e occurs in the negative electrode, and electrons (e) generated on the negative electrode surface are ion-conducted in the electrolytic solution and move to the positive electrode surface, and on the positive electrode surface, CoO ₂ + Li + e → A reaction of LiCoO ₂ occurs, and a current flows from the negative electrode to the positive electrode. When discharging, a reverse reaction occurs during charging, and current flows from the positive electrode to the negative electrode.

  However, in the electrolytic solution constituting such an electrochemical device, there is a problem that the organic solvent is likely to volatilize and the flash point is low, and a liquid leakage is likely to occur, resulting in lack of long-term reliability. Therefore, a material capable of improving these problems has been demanded.

  Then, examination which applies liquid room temperature molten salt at room temperature is performed (for example, refer nonpatent literature 1). Known as room temperature molten salts are complexes of aromatic quaternary ammonium halides such as N-butylpyridium and N-ethyl-N'-methyl-imidazolium with halogen aluminum, and mixtures of two or more lithium salts. (For example, see Non-Patent Document 2). However, the former complex has a problem of corrosivity due to halide ions, and the latter is a supercooled liquid which is thermodynamically unstable and solidifies with time.

  On the other hand, imidazolium salts and pyridium salts such as tetrafluoroborate anion and bistrifluoromethanesulfonylimide anion are relatively stable electrically and have been actively studied in recent years. However, performance such as ionic conductivity is not sufficient, and since it contains fluorine, there is a problem such as electrode corrosion, and a material for constituting an ionic conductor that exhibits excellent basic performance. There was room for ingenuity.

  In addition, the dicyanoamide salt of N-alkyl-N-methylpyrrolidinium or 1-alkyl-3-methylimidazolium was studied for thermal characteristics, viscosity, and qualitative potential stability. It is disclosed that it is useful as a low-viscosity ionic liquid (see, for example, Non-Patent Document 3). However, there is no disclosure regarding a technique for applying such a dicyanoamide salt to an ionic conductor material of an electrochemical device, and there is room for contrivance to make a material constituting an ionic conductor that exhibits excellent basic performance. there were.

For cyano-substituted salts, including cyano-substituted methides and amides, the group consisting of N-cyano-substituted amides, N-cyano-substituted sulfonamides, 1,1,1-dicyano-substituted sulfonyl methides and 1,1,1-dicyanoacyl methides An electrolyte containing at least one salt selected from the above and a matrix material is disclosed (for example, see Patent Document 1). In this electrolyte, a salt in the form of powder is prepared and dissolved in an organic solvent as a matrix material to form a liquid electrolyte or a solid polymer electrolyte. The present invention also relates to a solid conductive material containing an ionic dopant as a conductive species in an organic matrix. For example, N-methyl-N-propylpyrrolidinium dicyanoamide salt is used as an organic matrix and LiSO ₃ CF ₃ is used as an ionic dopant. (For example, refer to Patent Document 2). However, in these techniques, there is no disclosure of applying a compound in the form of a salt to the material of an electrolytic solution that is excellent as an ionic conductor of an electrochemical device, and making the salt itself liquid.

In addition, regarding an ionic compound including an anionic moiety bonded to the cationic moiety M ^{+ m} , M in the cationic moiety is hydroxonium, nitrosonium NO ⁺ , ammonium NH ₄ ⁺ , a metal cation having a valence m, a valence m Or an anionic moiety having one of the formulas R _D —Y—C (C≡N) ₂ ^— or Z—C (C≡N) ₂ ^—. It is disclosed that this ionic compound can be used for an ion conductive material or the like (see, for example, Patent Document 3). In such an ionic compound, the anionic portion is composed of only the carbon atom (C) as an anion element, and is a suitable material that constitutes an electrolytic solution that exhibits excellent basic performance. There was room for ingenuity.

Further, regarding a molten salt electrolyte for driving an electrolytic capacitor, an electrolyte salt composed of a nitrogen-containing heterocyclic cation having a conjugated double bond or a nitrogen-containing condensed heterocyclic cation having a conjugated double bond is melted or melted without using a solvent. Post-solidification is disclosed (for example, refer to Patent Document 4). This electrolyte is used for an electrolytic capacitor, and it is described that a carboxylate ion is used as an anion.
However, there is no disclosure of the temperature of conductivity, which is an important performance factor as an electrolytic solution for electrochemical devices, and the performance of ion conductivity and the like is not sufficient. There was room for ingenuity to make the material to be composed.

JP-T-2002-523879 (pages 1-7, 30-43) WO 01/15258 pamphlet (pages 14-17) Japanese translation of PCT publication No. 2000-508677 (page 1-12) Japanese Patent No. 3182793 (No. 1, pages 5-8)

Koura et al. Electrochem. Soc. 1993, 140, p. 602 C. A. Angell et al., Nature, 1933, 362, p. 137 Douglas R.D. MacFarlane et al., Chem. Commun. 2001, p. 1430-1431

  The present invention has been made in view of the above-mentioned present situation, improves ionic conductivity, suppresses corrosiveness to electrodes and the like, is stable over time, and is electrochemically stable at a high potential. It aims at providing the electrolyte solution material which is.

  As a result of various studies on materials constituting the electrolyte solution which is an ionic conductor, the present inventors have dissolved the electrolyte in the molten salt because it can be safely handled because it is in the form of a salt and thus can be safely handled. Focusing on the usefulness of ionic conductors in the liquid state, it contains two or more types of ionic liquids, even if the ionic liquid solidifies at a low temperature by itself and the ionic conductivity may not be measured. By adopting a form, it can be made excellent in ionic conductivity, by containing an ionic liquid in a specific combination, or by making the ionic conductivity at a specific temperature more than a specific range, It was found that the material can be suitable for the material constituting the conductor, and the inventors have conceived that the above problems can be solved brilliantly. In addition, when such a material does not have a fluorine atom, the corrosiveness to the electrode or the like can be suppressed due to this, and it can function stably over time, and constitutes an electrolytic solution. It has been found that it can function as a liquid material and can be suitable for electrochemical devices. Furthermore, by having a form having an anion or cation with a specific structure, it becomes a room temperature molten salt that stably maintains a molten state at room temperature, and does not contain a solvent, so that it does not volatilize outside at high temperatures, and for a long time. The present invention has also been found to be more suitable as a material constituting the electrolyte solution of an electrochemical device that can withstand the above-mentioned conditions.

That is, the present invention provides an electrolytic solution material comprising two or more ionic liquids, the electrolytic solution material is made as an essential ammonium cationite down to have at least one unsaturated bond, the following general Formula (1);

(In the formula, X, B, C, .a representing at least one element selected N and O or al is an integer of 1 or more, d is an integer of 0 or more.) Represented by It is an electrolyte solution material in which two or more anions are essential .

The electrolyte material is also an electrolyte material having an ionic conductivity at −55 ° C. of 1 × 10 ⁻⁶ S / cm or more.
Upper Symbol electrolyte material, under 30 ° C. atmosphere, glassy carbon electrode as a working electrode, using Ag electrode as a reference electrode, a platinum electrode as the counter electrode, respectively, sweep rate is 100 mV / s, the sweep range is determined by the natural potential ~3V when the potential is applied in the cyclic voltaic down cytometry measurements, the peak current of the first cycle of oxidation side _{i p1,} 2 and subsequent cycles of the peak current and _{i pn,} by _{(i p1 -i pn) / i} p1 × 100 is a value determined electrostatic position upon application 3 subsequent cycles of the peak current reduction rate is also the electrolyte material is 20% or more.
The present invention is described in detail below.

  The electrolyte material of the present invention has the above-described configuration, improves ionic conductivity, is not corrosive to electrodes and the like, is stable over time, and electrolyte salts can be decomposed even at a high potential. Suppressed and electrochemically stable, it is suitable as an electrolyte material that constitutes an ionic conductor, and has a charging and discharging mechanism for primary batteries, lithium (ion) secondary batteries, fuel cells, etc. It can be suitably applied to electrochemical devices such as electrolytic capacitors, electric double layer capacitors, solar cells and electrochromic display elements, in addition to the batteries having them.

It is a cross-sectional schematic diagram which shows one form of a lithium secondary battery. (A) is a perspective view which shows one form of an electrolytic capacitor, (b) is a cross-sectional schematic diagram which shows one form of an aluminum electrolytic capacitor. It is the cross-sectional schematic diagram which shows one form of an electrical double layer capacitor, and the enlarged schematic diagram of the electrode surface.

The electrolytic solution material of the present invention contains two or more ionic liquids, and (1) an ammonium cation having no unsaturated bond and an ammonium cation having an unsaturated bond are essential, and the general formula (1 ) An anion represented by (2), (2) an ammonium cation that does not have at least two unsaturated bonds, and one or both of them have a ring structure, (3) at least two kinds A form in which an ammonium cation having an unsaturated bond is essential, and the anion with which the cation is paired is different and the anion represented by the general formula (1) is essential, or (4) -55 ° C. form ion conductivity is 1 × 10 -6 ^{S /} cm or more, or in, (5) contains one or more ionic liquids, Contact cyclically Volta down cytometry measurements In the form Keru conductive position upon application 3 subsequent cycles of the peak current reduction of 20% or more, it may be these are combined two or more forms. Moreover, you may contain other cations other than the cation in each form. Furthermore, the anion represented by the general formula (1) may or may not be an anion constituting the ionic liquid. By setting it as such a form, it is excellent in ionic conductivity and can be made suitable for the material which comprises an ionic conductor. In addition, by adopting the form of (5) above, it becomes possible to obtain an ion conductor that exhibits sufficient withstand voltage characteristics and is electrochemically more stable. Further, any of the above (1) to (4) Or a combination of (1) and (5) above can be used as an electrolyte solution having both good ionic conductivity and voltage resistance, and further as a material constituting the ionic conductor. It becomes possible to make it suitable.

  The electrolytic solution material of the present invention can be suitably used as a medium (solvent) and / or an electrolyte that is a material constituting an electrolytic solution of an electrochemical device. The ionic liquid is composed of a compound composed of a cation and an anion. In the present invention, the ionic liquid contains one kind or two or more kinds of such ionic liquids. Need only contain two or more compounds composed of a cation and an anion, and the cation or anion may be the same. Such an ionic liquid is preferably a liquid having a constant volume and fluidity at 40 ° C., and specifically, a liquid of 200 mPa · s or less at 40 ° C. is preferable. More preferred is a liquid of 100 mPa · s or less, and still more preferred is a liquid of 50 mPa · s or less.

First, the form (4) will be described.
In the form (4), when the ionic conductivity at −55 ° C. is less than 1 × 10 ⁻⁶ S / cm, the electrolytic solution using the electrolytic solution material of the present invention has excellent ionic conductivity. It will not be possible to sufficiently maintain and function stably over time. Preferably, it is 1 × 10 ⁻⁵ S / cm or more, more preferably 5 × 10 ⁻⁵ S / cm or more, and further preferably 1 × 10 ⁻⁴ S / cm or more.
The ion conductivity is measured by, for example, a complex impedance method using an impedance analyzer HP4294A (trade name, manufactured by Toyo Technica) using a SUS electrode or an impedance analyzer SI1260 (trade name, manufactured by Solartron). Is preferred.

  In the form of the above (4), the following general formula (2);

(In the formula, L represents C, Si, N, P, S, or O. R is the same or different, and is an organic group, which may be bonded to each other. S is 3, 4, or 5) It is a value determined by the valence of the element L. It is preferable that the onium cation represented by Such a cation is preferably a cation that forms an ionic liquid contained in the electrolyte material of the present invention.

  Examples of the onium cation represented by the general formula (2) include the following general formula:

(In formula, R is the same as that of General formula (2).) What is represented is preferable.
Among these, the following onium cations are preferable.
(I) the following general formula;

10 heterocyclic onium cations represented by
(II) the following general formula;

5 types of unsaturated onium cations represented by
(III) the following general formula;

9 kinds of saturated ring onium cations represented by
In said general formula, R < ¹ > -R < ¹² > is the same or different, is an organic group, and may mutually be couple | bonded.
(IV) R is an alkyl group of _C 1 -C ₈ chain onium cations.
Among such onium cations, more preferably, L in the general formula (2) is a nitrogen atom, and more preferably the following general formula:

(Wherein R ^{1 to} R ¹² are the same as above), triethylmethylammonium, dimethylethylpropylammonium, diethylmethylmethoxyethylammonium, trimethylpropylammonium, trimethylbutyl And chain onium cations such as ammonium and trimethylhexylammonium.
Examples of the organic group of R ^{1 to} R ¹² include a hydrogen atom, a fluorine atom, an amino group, an imino group, an amide group, an ether group, an ester group, a hydroxyl group, a carboxyl group, a carbamoyl group, a cyano group, a sulfone group, and a sulfide group. Or a hydrocarbon group having 1 to 18 carbon atoms which may be linear, branched or cyclic, and may contain a nitrogen atom, an oxygen atom, a sulfur atom, etc., more preferably a hydrogen atom, a fluorine atom, A cyano group, a sulfone group, a hydrocarbon group having 1 to 8 carbon atoms, and a fluorocarbon group.

Next, the form (1) will be described.
In the above form (1), an ammonium cation having no unsaturated bond and an ammonium cation having an unsaturated bond, which are contained as essential components in the electrolyte material, may be cations in two or more ionic liquids. It may be derived from other compounds.
The ammonium cation having no unsaturated bond may be an alkyl ammonium cation composed of a single bond between elements. The single bond includes a single bond between the same elements and a single bond between different elements.
The ammonium cation having no unsaturated bond, (4) 9 kinds represented by formula (III) formula in the form of a saturated ring onium cations, the alkyl group of C ₁ ~C ₈ (IV) R Among the chain onium cations and the like, those in which L in the general formula (2) is a nitrogen atom are preferable.

The ammonium cation having an unsaturated bond may be an alkyl ammonium cation having an unsaturated bond. The unsaturated bond includes a multiple bond between the same elements such as a carbon-carbon multiple bond and a nitrogen-nitrogen multiple bond, and a multiple bond between different elements such as a carbon-nitrogen multiple bond. Such an unsaturated bond is preferably a conjugated double bond. A conjugated double bond refers to a double bond in the case where two or more double bonds are connected to each other with a single bond interposed therebetween.
Examples of the ammonium cation having an unsaturated bond include (I) 10 types of heterocyclic onium cations represented by the general formula in the form (4), and (II) 5 types of unsaturated oniums represented by the general formula. Among the cations and the like, those in which L in the general formula (2) is a nitrogen atom are preferable.

Next, the mode (2) will be described.
In the form of (2) above, in the ammonium cation having no two kinds of unsaturated bonds, (a) one of which has a ring structure and the other does not have a ring structure, or (b) both of which have a ring structure The ammonium cation having no unsaturated bond may be a cation in two or more ionic liquids contained in the electrolyte material, and may be derived from other compounds. Also good.
As the cation having a ring structure in the forms (a) and (b), for example, a cation having a ring structure is preferable among the ammonium cations having no unsaturated bond in the form (1). As an ammonium cation having no unsaturated bond having such a ring structure, for example, nine types of saturated ring onium cations represented by the general formula (III) in the form (4) are preferable.
Moreover, as a cation which does not have a ring structure in the form of said (a), the cation which does not have a ring structure among the ammonium cations which do not have an unsaturated bond in the form of said (1) is suitable. Such ammonium cations, e.g., the (4) (IV) in the form of R is a chain onium cation such as an alkyl group of C ₁ -C ₈ are preferred.

Next, the form (3) will be described.
In the form of (3) above, the ammonium cation having at least two types of unsaturated bonds contained as essential in the electrolyte material and the anion paired with the cation are two or more types contained in the electrolyte material. It may be a cation and an anion in the ionic liquid, or may be derived from other compounds.
As the ammonium cation having an unsaturated bond, an ammonium cation having an unsaturated bond in the form (1) is preferable. Such an ammonium cation having at least two kinds of unsaturated bonds is derived from a compound composed of a cation and an anion, and at least two kinds of anions paired with such a cation are contained in the electrolyte material. Will be.
The anion may be different. Different types are, for example, those having the same kind of anion constituents or having similar composition of anions but having different composition ratios. It is sufficient if the types are different.

Next, the form (5) will be described.
In the above (5), when the electric level is applied during the third cycle after the peak current reduction rate in the cyclic voltaic down cytometry measurement is less than 20%, it can not be more sufficiently exhibited voltage resistance, There is a possibility that an electrochemically more stable electrolytic solution cannot be obtained. Preferably, it is 20% or more, more preferably 40% or more, and still more preferably 60% or more. That is, as the electrolyte material in the form of (5), cyclic Volta emissions cytometry in conductive position upon application 3 subsequent cycles of the peak current reduction ratio measurement preferably at least 20%, more preferably 60% or more.
Also in the embodiment (5), it is preferred conductive position upon application after the second cycle peak current reduction rate in the cyclic voltaic down cytometry measurement is 10% or more, more not less than 20% preferable.
Here, the conductive position upon application after the second cycle peak current reduction rate, when electric position applied and the peak current of the first cycle i _p1, the _second and subsequent cycles of the peak current and i _pn, (i _p1− i _pn ) / i _p1 × 100.

The above cyclic Volta down cytometry (CV: cyclic
It is preferable that the measurement is performed by using a standard voltammetric tool HSV-100 (trade name, manufactured by Hokuto Denko) using a three-electrode cell in an atmosphere of 30 ° C., for example. The measurement conditions in this case are as follows.
(Measurement condition)
Working electrode: Glassy carbon electrode, Reference electrode: Ag electrode, Counter electrode: Platinum electrode Sweep speed: 100 mV / s
Sweep range: natural potential to 3V

The electrolyte material in the form (5) preferably has a viscosity at 40 ° C. of 200 mPa · s or less. If the viscosity exceeds 200 mPa · s, the ionic conductivity may not be sufficiently improved. More preferably, it is 100 mPa * s or less, More preferably, it is 50 mPa * s or less.
As a method for measuring the viscosity, for example, a method of measuring at 25 ° C. using a TV-20 viscometer coplate type (manufactured by Tokimec) is suitable.

  The electrolyte material in the form of the above (5) also contains an onium cation represented by the general formula (2) and / or an anion represented by the general formula (1). This makes it possible to obtain an electrolytic solution having both better ionic conductivity and voltage resistance. More preferably, it contains both the onium cation represented by the general formula (2) and the anion represented by the general formula (1). Such an onium cation and / or anion is preferably a cation and / or anion that forms an ionic liquid contained in the electrolytic solution material of the present invention.

  It is preferable that the electrolyte material in the form (5) further contains two or more ionic liquids. As a result, decomposition of the electrolyte salt composed of the ionic liquid at a high potential is sufficiently suppressed, and an electrochemically more stable electrolyte can be obtained.

In the electrolyte material of the present invention, a form in which a nitrogen heterocyclic cation having a conjugated double bond is essential is also a preferred embodiment. The nitrogen heterocyclic cation having such a conjugated double bond may or may not be an ammonium cation having an unsaturated bond contained as essential in the above forms (1) and (3). The form (2) further contains a nitrogen heterocyclic cation having such a conjugated double bond.
Examples of the nitrogen heterocyclic cation having a conjugated double bond include (I) 10 types of heterocyclic onium cations represented by the general formula in the form (4), and (II) 5 types of general formulas represented by the general formula. Among unsaturated onium cations and the like, those having a conjugated double bond and L in the general formula (2) being a nitrogen atom are preferred.

  Regarding the abundance of the cation in the electrolyte material of the present invention, the lower limit of the content of the compound from which the cation is derived is preferably 1% by mass with respect to 100% by mass of the electrolyte material. More preferably, it is 5 mass%, More preferably, it is 10 mass%. As an upper limit, 99.5 mass% is preferable. More preferably, it is 95 mass%, More preferably, it is 90 mass%.

In the anion represented by the general formula (1) contained as essential in the form of (1) or (3), X is B, C, N, O, Al, Si, P, S, As, and Although it represents at least one element selected from Se, C, N or S is preferred. More preferably, it is C or N. M ¹ and M ² are the same or different and each represents an organic linking group, each independently a linking group selected from —S—, —O—, —SO ₂ —, —CO—, preferably , _-SO 2 -, - it is a CO-. Q is an organic group, a hydrogen atom, a halogen _{atom, C p F (2p + 1} -q) H q, OC p F (2p + 1-q) H q, SO 2 C p F (2p + 1-q) H q, _{CO 2 C p F (2p +} 1-q) H q, SO 3 C 6 F 5-r H r, NO 2 ( wherein a 1 ≦ p ≦ 6,0 <q ≦ 13,0 <r ≦ 5) Etc. are preferred. More preferably a fluorine atom, a chlorine _{atom, C p F (2p + 1} -q) H q, SO 2 C p F (2p + 1-q) H q. Further, a is an integer of 1 or more, and b, c, d, and e are integers of 0 or more, but a, d, and e are determined by the valence of the element X, for example, X When X is a sulfur atom, a = 1, d = 0, e = 0, and when X is a nitrogen atom, (1) a = 2, d = 0, e = 0, (2) a = 1, d = 1, e = 0, or (3) a = 1, d = 0, or e = 1. Also, b and c are preferably 0.

Examples of the anion represented by the general formula (1) include a dicyanoamide anion (DCA), a thiocyanate anion, a tricyanomethide anion (TCM), and a cyanooxy anion (CYO). It is preferable because it is highly corrosive.
A compound composed of such an anion and the onium cation as described above becomes a room temperature molten salt that stably maintains a molten state at room temperature, and the electrolytic solution material of the present invention containing such a molten salt is used for a long time. Therefore, it is suitable as a material for an ionic conductor of an electrochemical device that can withstand high temperatures. In addition, molten salt is what can maintain a liquid state stably in the temperature range of room temperature to 80 degreeC. In addition to the anion represented by the above general formula (1), dicarboxylic acid anions such as bistrifluoromethanesulfonylimide anion (TFSI), tetrafluoroborate anion, phthalic acid, maleic acid, methyl sulfate, ethyl sulfate, etc. The sulfate ester anion may be contained. Also, fluorine-containing inorganic ions such as fluorine-containing inorganic ions, hexafluorophosphate ions, hexafluoroarsenate ions, hexafluoroantimonate ions, hexafluoroniobate ions, hexafluorotantalate ions; hydrogen phthalate ions, maleic acid Carboxylic acid ions such as hydrogen ion, salicylic acid ion, benzoic acid ion and adipic acid ion; sulfonic acid such as benzenesulfonic acid ion, toluenesulfonic acid ion, dodecylbenzenesulfonic acid ion, trifluoromethanesulfonic acid ion, perfluorobutanesulfonic acid Inorganic oxo acid ions such as borate ion and phosphate ion; bis (trifluoromethanesulfonyl) imide ion, bis (pentafluoroethanesulfonyl) imide ion, tris (trifluoromethanesulfuric acid) Nyl) methide ion, perfluoroalkylfluoroborate ion, perfluoroalkylfluorophosphate ion, borodicatecholate, borodiglycolate, borodisalicylate, borotetrakis (trifluoroacetate), bis (oxalato) borate, etc. You may contain 1 type, or 2 or more types, such as a coordinate borate ion.

The anion contained in the above forms (2) and (4) is not particularly limited as long as it functions suitably when used as an electrolytic solution. For example, the anion represented by the above general formula (1), bistrifluoro Methanesulfonylimide anion (TFSI), tetrafluoroborate anion and the like are preferable.
As the abundance of anions in the electrolyte material of the present invention, the lower limit is preferably 0.5 mol with respect to 1 mol of cations present in the electrolyte material. More preferably, it is 0.8 mol. The upper limit is preferably 2.0 mol. More preferably, it is 1.2 mol.

  The electrolyte material of the present invention preferably further comprises an alkali metal salt and / or an alkaline earth metal salt. The electrolytic solution material of the present invention containing such an alkali metal salt and / or alkaline earth metal salt contains an electrolyte and is suitable as a material for an electrolytic solution of an electrochemical device. As the alkali metal salt, a lithium salt, a sodium salt, and a potassium salt are preferable, and as the alkaline earth metal salt, a calcium salt and a magnesium salt are preferable. More preferably, it is a lithium salt.

The alkali metal salt and / or alkaline earth metal salt may be a compound that requires an anion as described above, or other compounds. The electrolyte salt is preferably an electrolyte salt having a large dissociation constant in the electrolytic solution. For example, alkali metal salts or alkaline earths of trifluoromethanesulfonic acid such as LiCF ₃ SO ₃ , NaCF ₃ SO ₃ , KCF ₃ SO _3, etc. Metal salt; Alkali metal salt or alkaline earth metal salt of perfluoroalkanesulfonic acid imide such as LiN (CF ₃ SO ₃ ) ₃ , LiN (CF ₃ CF ₃ SO ₂ ) ₂ ; LiPF ₆ , NaPF ₆ , KPF _6, etc. Hexafluorophosphoric acid alkali metal salts and alkaline earth metal salts; LiClO ₄ , NaClO _{4 and} other perchloric acid alkali metal salts and alkaline earth metal salts; LiBF ₄ and NaBF _{4 and} other tetrafluoroborate salts; LiAsF ₆ , Alkali metal salts such as LiI, NaI, NaAsF ₆ and KI are preferred. Among these, from the viewpoint of solubility and ionic conductivity, LiPF ₆ , LiBF ₄ , LiAsF ₆ , and alkali metal salts or alkaline earth metal salts of perfluoroalkanesulfonic acid imide are preferable.

The electrolyte material may contain other electrolyte salts, such as quaternary ammonium salts of perchloric acid such as tetraethylammonium perchlorate; tetrafluoroboric acid such as (C ₂ H ₅ ) ₄ NBF _4. A quaternary ammonium salt such as a quaternary ammonium salt or (C ₂ H ₅ ) ₄ NPF ₆ ; a quaternary phosphonium salt such as (CH ₃ ) ₄ P · BF ₄ or (C ₂ H ₅ ) ₄ P · BF ₄ is preferred. In view of solubility and ionic conductivity, quaternary ammonium salts are preferred.

  The amount of the electrolyte salt in the electrolytic solution material of the present invention is preferably 0.1% by mass or more and more preferably 50% by mass or less with respect to 100% by mass of the electrolytic solution material. If it is less than 0.1% by mass, the absolute amount of ions may be insufficient and the ionic conductivity may be reduced. If it exceeds 50% by mass, the movement of ions may be greatly inhibited. More preferably, it is 30 mass% or less.

  The electrolyte solution material of the present invention can also be suitably used as a material for an ion conductor constituting a hydrogen battery by containing protons. Such an electrolyte material further comprising protons is one of the preferred embodiments of the present invention. In the present invention, the inclusion of a compound that can dissociate to generate a proton causes the proton to be present in the electrolytic solution.

  The abundance of protons in the electrolyte material of the present invention is preferably 0.01 mol / L or more, more preferably 10 mol / L or less, with respect to the electrolyte material. If it is less than 0.01 mol / L, the absolute amount of protons may be insufficient and proton conductivity may be reduced. When it exceeds 10 mol / L, there is a possibility that proton transfer is greatly inhibited. More preferably, it is 5 mol / L or less.

The electrolyte material of the present invention preferably further comprises an organic solvent. Thereby, the ionic conductivity is further improved.
Examples of the organic solvent include ethers such as 1,2-dimethoxyethane, tetotahydrofuran, 2-methyltetrahydrofuran, crown ether, triethylene glycol methyl ether, tetraethylene glycol dimethyl ether, dioxane; ethylene carbonate, propylene carbonate Carbonates such as diethyl carbonate and methyl ethyl carbonate; chain carbonates such as dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, diphenyl carbonate and methyl phenyl carbonate; ethylene carbonate, propylene carbonate, 2,3-dimethyl ethylene carbonate, Cyclic carbonates such as butylene carbonate, vinylene carbonate, 2-vinylethylene carbonate; methyl formate, methyl acetate, propionic acid, methyl propionate, ethyl acetate, propyl acetate, butyl acetate Aliphatic carboxylic acid esters such as amyl acetate; Aromatic carboxylic acid esters such as methyl benzoate and ethyl benzoate; Carboxylic acid esters such as γ-butyrolactone, γ-valerolactone, and δ-valerolactone; Trimethyl phosphate , Phosphate esters such as ethyldimethyl phosphate, diethylmethyl phosphate, triethyl phosphate; nitriles such as acetonitrile, propionitrile, methoxypropionitrile, glutaronitrile, adiponitrile, 2-methylglutaronitrile; N -Amides such as methylformamide, N-ethylformamide, N, N-dimethylformamide, N, N-dimethylacetamide, N-methylpyrrolidinone, N-methylpyrrolidone, N-vinylpyrrolidone; dimethylsulfone, ethylmethylsulfone, diethyl Sulfo , Sulfolane, 3-methylsulfolane, sulfur compounds such as 2,4 dimethylsulfolane: alcohols such as ethylene glycol, propylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether; ethylene glycol dimethyl ether, ethylene glycol diethyl ether, 1 Ethers such as 1,4-dioxane, 1,3-dioxolane, tetrahydrofuran, 2-methyltetrahydrofuran, 2,6-dimethyltetrahydrofuran, tetrahydropyran; sulfoxides such as dimethyl sulfoxide, methylethyl sulfoxide, diethyl sulfoxide; benzonitrile, tolunitrile Aromatic nitriles such as nitromethane, 1,3-dimethyl-2-imidazolidinone, 1,3-dimethyl-3,4,5, Examples thereof include 6-tetrahydro-2 (1H) -pyrimidinone and 3-methyl-2-oxazolidinone, and one or more of these are preferable. Among these, carbonate esters, aliphatic esters, and ethers are more preferable, carbonates are more preferable, and cyclic esters such as γ-butyrolactone and γ-valerolactone are most preferable.

  The amount of the organic solvent and water in the electrolytic solution material of the present invention is 1 to 20% by mass with respect to 100% by mass of the electrolytic solution from the viewpoint of improving conductivity and reducing the stability of the electrolytic solution due to volatilization of the solvent. Is preferable, more preferably 1 to 10% by mass, and still more preferably 1 to 5% by mass. If it is less than 1% by mass, the ionic conductivity may be reduced. If it exceeds 20% by mass, the stability may deteriorate due to volatilization of the solvent or the like.

  In the present invention, when a non-aqueous solvent is used as the solvent, it is preferable to control the water content, and thereby, withstand voltage characteristics and life characteristics of an electrochemical device using such an electrolyte solution. Will be stable. Moreover, although the requirements for high heat resistance are satisfied, by controlling the moisture content, the influence of moisture is more sufficiently suppressed, and these characteristics are more fully exhibited. Specifically, when a non-aqueous solvent is used, it is preferable that the water concentration in the electrolytic solution is 1% by mass or less. More preferably, it is 0.1 mass% or less. Moreover, it is preferable that it is 0.01 mass% or more, and it becomes possible to make sufficient the chemical conversion property at the time of repairing an anodic oxide film by this.

The electrolyte material of the present invention may contain one or more components other than those described above as long as the effects of the present invention are exhibited. For example, the electrolyte material may contain various inorganic oxide fine particles.
As the inorganic oxide fine particles, those having non-electron conductivity and electrochemical stability are preferable, and those having ion conductivity are more preferable. As such fine particles, ion conductive or nonconductive ceramic fine particles such as α, β, γ-alumina, silica, titania, zirconia, magnesia, barium titanate, titanium oxide, and hydrotalcite are suitable.

The specific surface area of the inorganic oxide fine particles is preferably as large as possible, preferably 5 m ² / g or more, more preferably 50 m ² / g or more by the BET method. The crystal particle size of such inorganic oxide fine particles may be mixed with other components in the electrolytic solution, but the size (average crystal particle size) is preferably 0.01 μm or more, and more preferably 20 μm or less. More preferably, it is 0.01 μm or more and 2 μm or less.
As the shape of the inorganic oxide fine particles, various shapes such as a spherical shape, an oval shape, a cubic shape, a rectangular parallelepiped shape, a cylindrical shape, and a rod shape can be used.
The amount of the inorganic oxide fine particles added is preferably 100% by mass or less with respect to the electrolyte material. If it exceeds 100% by mass, the ion conductivity may be reduced. More preferably, it is 0.1% by mass or more and 20% by mass or less.

The electrolyte material of the present invention may also contain various additives in addition to the salt and solvent described above. The purpose of adding the additive is various, and includes improvement of electrical conductivity, improvement of thermal stability, suppression of electrode deterioration due to hydration and dissolution, suppression of gas generation, improvement of withstand voltage, improvement of wettability, etc. it can. Examples of such additives include nitro compounds such as p-nitrophenol, m-nitroacetophenone, and p-nitrobenzoic acid, dibutyl phosphate, monobutyl phosphate, dioctyl phosphate, monooctyl phosphonate, monophosphate Boron compounds such as phosphorus compounds such as boric acid or boric acid and polyhydric alcohols (ethylene glycol, glycerin, mannitol, polyvinyl alcohol, etc.) and polysaccharides, nitroso compounds, urea compounds, arsenic compounds, titanium compounds, Silicic acid compounds, aluminate compounds, nitric acid and nitrous acid compounds, 2-hydroxy-N-methylbenzoic acid, benzoic acids such as di (tri) hydroxybenzoic acid, gluconic acid, dichromic acid, sorbic acid, dicarboxylic acid, EDTA , Fluorocarboxylic acid, picric acid, suberic acid, adipine , Sebacic acid, heteropolyacid (tungstic acid, molybdic acid), gentisic acid, borodigentisic acid, salicylic acid, N-aminosalicylic acid, borodiprotocatechuic acid, borodipyrocatechol, bamonic acid, boric acid, borodiresorcylic acid, resorcylic acid, Borodiprotocaquelic acid, glutaric acid, acids such as dithiocarbamic acid, esters thereof, amides and salts thereof, silane coupling agents, silicon compounds such as silica and aminosilicate, amine compounds such as triethylamine and hexamethylenetetramine, L- Amino acids, benzoles, polyphenols, 8-oxyquinoline, hydroquinone, N-methylpyrocatechol, quinoline and thioanisole, thiocresol, thiobenzoic acid and other sulfur compounds, sorbitol, L-histidine, etc. It may be used or two or more.
Although content of the said additive is not specifically limited, For example, it is preferable that it is the range of 0.1-20 mass% with respect to 100 mass% of electrolyte material. More preferably, it is the range of 0.5-10 mass%.

  The electrolyte material of the present invention is a primary battery, a battery having a charging / discharging mechanism such as a lithium (ion) secondary battery or a fuel cell, an electrolytic capacitor, an electric double layer capacitor, an electrochemical cell such as a solar cell or an electrochromic display element. It is suitable as a material for an ionic conductor constituting the device. A lithium secondary battery, an electrolytic capacitor or an electric double layer capacitor using such an electrolyte material of the present invention is also one aspect of the present invention.

  When an electrochemical device is constituted using the electrolytic solution material of the present invention, as a preferable form of the electrochemical device, the basic component includes an ionic conductor, a negative electrode, a positive electrode, a current collector, a separator, and a container. is there.

  As the ionic conductor, a mixture of an electrolyte and an organic solvent is suitable. If an organic solvent is used, this ionic conductor is generally called an electrolytic solution. The electrolytic solution material of the present invention can be suitably applied as an alternative to the electrolyte or organic solvent in the electrolytic solution in such an ion conductor, and the electrolytic solution material of the present invention is used as a material for the ion conductor. In an electrochemical device, at least one of these will be comprised by the electrolyte material of this invention. Among these, it is preferable to use as an alternative of the organic solvent in electrolyte solution.

  The organic solvent may be an aprotic solvent that can dissolve the electrolytic solution material of the present invention, and the same organic solvents as described above are suitable. However, when two or more kinds of mixed solvents are used, when the electrolyte contains Li ions, among these organic solvents, an aprotic solvent having a dielectric constant of 20 or more and an aprotic solvent having a dielectric constant of 10 or less are used. It is preferable to prepare an electrolytic solution by dissolving in a mixed solvent. In particular, when a lithium salt is used, the solubility in an aprotic solvent having a dielectric constant of 10 or less, such as diethyl ether or dimethyl carbonate, is low, and sufficient ionic conductivity cannot be obtained by itself. Although the aprotic solvent alone has high solubility but high viscosity, ions are difficult to move and sufficient ionic conductivity cannot be obtained. If these are mixed, appropriate solubility and mobility can be ensured, and sufficient ionic conductivity can be obtained.

The electrolyte concentration in the ion conductor is preferably 0.01 mol / dm ³ or more, and more preferably a saturation concentration or less. If it is less than 0.01 mol / dm ³ , the ionic conductivity is low, such being undesirable. More preferably, 0.1 mol / dm ³ or more, it is 1.5 mol / dm ³ or less.

  In the case of a lithium battery, the negative electrode material is preferably lithium metal or an alloy of lithium and another metal. In the case of a lithium ion battery, a material using a phenomenon called intercalation of carbon, natural graphite, metal oxide, or the like obtained by firing a polymer, an organic substance, pitch, or the like is preferable. In the case of the electric double layer capacitor, activated carbon, porous metal oxide, porous metal, and conductive polymer are suitable.

As the positive electrode material, in the case of lithium batteries and lithium ion batteries, lithium-containing oxides such as LiCoO ₂ , LiNiO ₂ , LiMnO ₂ , LiMn ₂ O ₄ ; oxides such as TiO ₂ , V ₂ O ₅ , MoO ₃ ; Sulfides such as TiS ₂ and FeS; conductive polymers such as polyacetylene, polyparaphenylene, polyaniline, and polypyrrole are suitable. In the case of the electric double layer capacitor, activated carbon, porous metal oxide, porous metal, and conductive polymer are suitable.

Hereinafter, (1) a lithium secondary battery, (2) an electrolytic capacitor, and (3) an electric double layer capacitor using the electrolytic solution material of the present invention will be described in more detail.
(1) Lithium secondary battery A lithium secondary battery is composed of a positive electrode, a negative electrode, a separator interposed between the positive electrode and the negative electrode, and an ionic conductor using the electrolyte material of the present invention as basic constituent elements. It is. In this case, the electrolyte material of the present invention contains a lithium salt as an electrolyte. Such a lithium secondary battery is preferably a non-aqueous electrolyte lithium secondary battery that is a lithium secondary battery other than the water electrolyte. A schematic cross-sectional view of one embodiment of a lithium secondary battery is shown in FIG. This lithium secondary battery uses coke as a negative electrode active material, which will be described later, and uses a compound containing Co as the positive electrode active material. The reaction of ₆ Li → 6C + Li + e occurs, and the electron (e) generated on the negative electrode surface is ion-conductive in the electrolyte and moves to the positive electrode surface. On the positive electrode surface, the reaction of CoO ₂ + Li + e → LiCoO ₂ occurs. Current flows from the positive electrode to the positive electrode. When discharging, a reverse reaction occurs during charging, and current flows from the positive electrode to the negative electrode. Thus, electricity is stored or supplied by a chemical reaction by ions.

The negative electrode is preferably prepared by applying a negative electrode mixture containing a negative electrode active material, a negative electrode conductive agent, a negative electrode binder, and the like to the surface of the negative electrode current collector. The negative electrode mixture may contain various additives in addition to the conductive agent and the binder.
As the negative electrode active material, metallic lithium, a material capable of inserting and extracting lithium ions, and the like are suitable. Suitable materials that can occlude and release lithium ions include metallic lithium; pyrolytic carbon; coke such as pitch coke, needle coke, and petroleum coke; graphite; glassy carbon; phenol resin, furan resin, and the like. Organic polymer compound fired body fired at temperature and carbonized; carbon fiber; carbon material such as activated carbon; polymer such as polyacetylene, polypyrrole, polyacene; Li _4/3 Ti _5/3 O ₄ , TiS ₂ etc. Lithium-containing transition metal oxides or transition metal sulfides; metals such as Al, Pb, Sn, Bi, and Si that are alloyed with alkali metals; AlSb, Mg ₂ Si, in which alkali metals can be inserted between lattices, and cubic intermetallic compounds of NiSi _{2, etc., Li 3-f G f N} : lithium nitrogen compounds in (G transition metals), etc. Etc. are preferred. These can use 1 type (s) or 2 or more types. Among these, metallic lithium and carbon materials that can occlude / release alkali metal ions are more preferable.

  The negative electrode conductive agent may be an electronic conductive material, such as natural graphite such as flake graphite, graphite such as artificial graphite; acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black, etc. Carbon black; conductive fibers such as carbon fibers and metal fibers; metal powders such as carbon fluoride, copper and nickel; organic conductive materials such as polyphenylene derivatives are suitable. These can use 1 type (s) or 2 or more types. Among these, artificial graphite, acetylene black, and carbon fiber are more preferable. The amount of the negative electrode conductive agent used is preferably 1 to 50 parts by weight, and more preferably 1 to 30 parts by weight with respect to 100 parts by weight of the negative electrode active material. Further, since the negative electrode active material has electronic conductivity, a negative electrode conductive agent need not be used.

  The binder for the negative electrode may be either a thermoplastic resin or a thermosetting resin. Polyethylene, polypropylene, polytetrafluoroethylene, polyvinylidene fluoride, styrene butadiene rubber, tetrafluoroethylene-hexafluoropropylene Polymer, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-chlorotrifluoroethylene copolymer, ethylene-tetrafluoroethylene copolymer, polychlorotri Fluoroethylene, vinylidene fluoride-pentafluoropropylene copolymer, propylene-tetrafluoroethylene copolymer, ethylene-chlorotrifluoroethylene copolymer, vinylidene fluoride-hexafluoropropylene -Tetrafluoroethylene copolymer, vinylidene fluoride-perfluoromethyl vinyl ether-tetrafluoroethylene copolymer, ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer, ethylene-methyl acrylate copolymer, An ethylene-methyl methacrylate copolymer, polyamide, polyurethane, polyimide, polyvinyl pyrrolidone, and a copolymer thereof are preferable. These can use 1 type (s) or 2 or more types. Among these, styrene butadiene rubber, polyvinylidene fluoride, ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer, ethylene-methyl acrylate copolymer, ethylene-methyl methacrylate copolymer, polyamide, polyurethane, More preferred are polyimide, polyvinylpyrrolidone and copolymers thereof.

  The current collector for the negative electrode may be an electronic conductor that does not cause a chemical change inside the battery. Stainless steel, nickel, copper, titanium, carbon, conductive resin, carbon on the surface of copper or stainless steel, Those having nickel or titanium adhered or coated thereon are suitable. Among these, copper and alloys containing copper are more preferable. These can use 1 type (s) or 2 or more types. Further, the surface of the negative electrode current collector can be oxidized and used. Furthermore, it is desirable to make the current collector surface uneven. As the shape of the negative electrode current collector, a foil, a film, a sheet, a net, a punched one, a lath body, a porous body, a foamed body, a molded body of a fiber group, and the like are suitable. The thickness of the current collector is preferably 1 to 500 μm.

The positive electrode is preferably prepared by coating a positive electrode mixture containing a positive electrode active material, a positive electrode conductive agent, a positive electrode binder, and the like on the surface of the positive electrode current collector. The positive electrode mixture may contain various additives in addition to the conductive agent and the binder.
Examples of the positive electrode active material include metal Li, Li _x CoO ₂ , Li _x NiO ₂ , Li _x MnO ₂ , Li _x Co _y Ni _1-y O ₂ , Li _x Co _y J _1-y O _z , and Li _x Ni. _{1-y J y O z,} Li x Mn 2 O 4, Li x Mn 2-y J y O 4; MnO 2, V g O h, Cr g O h (g and h is an integer of 1 or more) such as An oxide containing no lithium is suitable. These can use 1 type (s) or 2 or more types.
J represents at least one element selected from Na, Mg, Sc, Y, Mn, Fe, Co, Ni, Cu, Zn, Al, Cr, Pb, Sb, and B. X is 0 ≦ x ≦ 1.2, y is 0 ≦ y ≦ 0.9, z is 2.0 ≦ z ≦ 2.3, and x is charge / discharge of the battery. Will increase or decrease. In addition, as the positive electrode active material, a transition metal chalcogenide, a vanadium oxide or niobium oxide which may contain lithium, an organic conductive material composed of a conjugated polymer, a chevrel phase compound, or the like may be used. The average particle diameter of the positive electrode active material particles is preferably 1 to 30 μm.

  The positive electrode conductive agent may be any electron conductive material that does not cause a chemical change in the charge / discharge potential of the positive electrode active material used, and is the same as the negative electrode conductive agent described above; metal powder such as aluminum and silver Conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide are suitable. These can use 1 type (s) or 2 or more types. Among these, artificial graphite, acetylene black, and nickel powder are more preferable. The amount of the positive electrode conductive agent used is preferably 1 to 50 parts by weight, and more preferably 1 to 30 parts by weight with respect to 100 parts by weight of the positive electrode active material. When carbon black or graphite is used, the amount is preferably 2 to 15 parts by weight with respect to 100 parts by weight of the positive electrode active material.

  The positive electrode binder may be either a thermoplastic resin or a thermosetting resin, other than the styrene butadiene rubber in the negative electrode binder described above, and tetrafluoroethylene-hexafluoroethylene copolymer. A coalescence or the like is preferred. These can use 1 type (s) or 2 or more types. Among these, polyvinylidene fluoride and polytetrafluoroethylene are more preferable.

  The positive electrode current collector may be any electron conductor that does not cause a chemical change in the charge / discharge potential of the positive electrode active material to be used. The surface of stainless steel, aluminum, titanium, carbon, conductive resin, aluminum or stainless steel Those having carbon or titanium adhered or coated thereon are suitable. These can use 1 type (s) or 2 or more types. Among these, aluminum or an alloy containing aluminum is preferable. Further, the surface of the positive electrode current collector can be oxidized and used. Furthermore, it is desirable to make the current collector surface uneven. The shape and thickness of the positive electrode current collector are the same as those of the negative electrode current collector described above.

The separator is preferably an insulating microporous thin film having a large ion permeability and a predetermined mechanical strength, and has a function of closing the pores at a certain temperature or higher and increasing the resistance. preferable. Materials include porous synthetic resin films of polyolefin polymers such as polyethylene and polypropylene, woven or non-woven fabrics made of organic materials such as polypropylene and fluorinated polyolefins, glass fibers, and inorganic materials from the viewpoint of organic solvent resistance and hydrophobicity. A woven fabric or a non-woven fabric is preferably used. The pore diameter of the pores of the separator is preferably in a range in which the positive electrode active material, the negative electrode active material, the binder, and the conductive agent detached from the electrode do not pass through, and is preferably 0.01 to 1 μm. As a thickness of a separator, it is preferable that it is 5-300 micrometers, More preferably, it is 10-50 micrometers. Moreover, as a porosity, it is preferable that it is 30 to 80%.
Moreover, it is preferable that the surface of the separator is modified in advance so as to reduce its hydrophobicity by a corona discharge treatment, a plasma discharge treatment, or other wet treatment using a surfactant. As a result, the wettability of the separator surface and the inside of the pores is improved, and the increase in the internal resistance of the battery can be suppressed as much as possible.

As the lithium secondary battery, a positive electrode mixture or a negative electrode mixture containing a gel holding an electrolyte solution in a polymer material, or a porous separator made of a polymer material holding an electrolyte solution is used as a positive electrode or a negative electrode. You may be comprised by integrating. The polymer material is not particularly limited as long as it can hold an electrolytic solution, and a copolymer of vinylidene fluoride and hexafluoropropylene is preferable.
Examples of the shape of the lithium secondary battery include a coin shape, a button shape, a sheet shape, a laminated shape, a cylindrical shape, a flat shape, a square shape, and a large size used for an electric vehicle.

(2) Electrolytic Capacitor The electrolytic capacitor is composed of an anode foil, a cathode foil, a capacitor element composed of electrolytic paper and a lead wire sandwiched between the anode foil and the cathode foil, and the electrolytic solution material of the present invention. The ion conductor used, a bottomed cylindrical outer case, and a sealing body for sealing the outer case are configured as basic components. A perspective view of one embodiment of the capacitor element is shown in FIG. The electrolytic capacitor in the present invention is obtained by impregnating a capacitor element with an electrolytic solution that is an ionic conductor using the electrolytic solution material of the present invention, and housing the capacitor element in a bottomed cylindrical outer case, It is possible to obtain the sealing member by attaching a sealing body to the portion and sealing the outer case by drawing the end portion of the outer case. As such an electrolytic capacitor, an aluminum electrolytic capacitor, a tantalum electrolytic capacitor, and a niobium electrolytic capacitor are suitable. A schematic cross-sectional view of one embodiment of the aluminum electrolytic capacitor is shown in FIG.

As the anode foil, an aluminum foil having a purity of 99% or more is chemically or electrochemically etched in an acidic solution and subjected to a surface expansion treatment, and then in an aqueous solution such as ammonium borate, ammonium phosphate, or ammonium adipate. A material obtained by performing a chemical conversion treatment and forming an anodized film layer on the surface thereof can be used.
The cathode foil is selected from one or more metal nitrides selected from titanium nitride, zirconium nitride, tantalum nitride and niobium nitride, and / or titanium, zirconium, tantalum and niobium on part or all of the surface. An aluminum foil formed with a film composed of one or more metals can be used.
Examples of the method for forming the film include a vapor deposition method, a plating method, a coating method, and the like. As a portion for forming the film, the entire surface of the cathode foil may be coated, or if necessary, For example, only one surface of the cathode foil may be coated with metal nitride or metal.

The lead wire is preferably composed of a connection part in contact with the anode foil and the cathode foil, a round bar part, and an external connection part. The lead wires are electrically connected to the anode foil and the cathode foil by means such as stitching and ultrasonic welding at the connection portions. Further, the connecting portion and the round bar portion in the lead wire are preferably made of high-purity aluminum, and the external connecting portion is preferably made of a copper-plated steel wire subjected to solder plating. In addition, an aluminum oxide layer formed by anodizing with an aqueous ammonium borate solution, an aqueous ammonium phosphate solution, or an aqueous ammonium adipate solution may be formed on part or all of the surface of the connecting portion with the cathode foil and the round bar portion. An insulating layer such as a ceramic coating layer made of Al ₂ O ₃ , SiO ₂ , ZrO ₂ or the like can be formed.

The exterior case is preferably made of aluminum.
The sealing body is preferably provided with a through hole through which each lead wire is led out, and is preferably composed of an elastic rubber such as butyl rubber, and the butyl rubber is, for example, a copolymer of isobutylene and isoprene. After adding and kneading a reinforcing rubber (carbon black, etc.), a bulking agent (clay, talc, calcium carbonate, etc.), a processing aid (stearic acid, zinc oxide, etc.), a vulcanizing agent, etc. A molded rubber elastic body can be used. Examples of vulcanizing agents include alkylphenol formalin resins; peroxides (dicumyl peroxide, 1,1-di- (t-butylperoxy) -3,3,5-trimethylcyclohexane, 2,5-dimethyl-2,5- Di- (t-butylperoxy) hexane etc.); quinoids (p-quinone dioxime, p, p'-dibenzoylquinone dioxime etc.); sulfur etc. can be used. Note that it is more preferable to coat the surface of the sealing body with a resin such as Teflon (registered trademark) or to attach a plate such as bakelite because the permeability of the solvent vapor is reduced.
As the separator, paper such as manila paper or kraft paper is usually used, but non-woven fabrics such as glass fiber, polypropylene and polyethylene can also be used.

  The electrolytic capacitor may have a hermetic seal structure or a structure sealed in a resin case (for example, described in JP-A-8-148384). In the case of an aluminum electrolytic capacitor with a rubber seal, gas permeates through rubber to some extent, so that the solvent evaporates from the inside of the capacitor to the atmosphere in a high temperature environment, and from the atmosphere to the inside of the capacitor in a high temperature and high humidity environment. Moisture may be mixed into the capacitor, and under these harsh environments, the capacitor may cause undesirable characteristic changes such as a decrease in capacitance. On the other hand, a capacitor with a hermetic seal structure or a structure sealed in a resin case has a very small amount of gas permeation, and thus exhibits stable characteristics even in such a harsh environment.

(3) Electric Double Layer Capacitor The electric double layer capacitor is composed of a negative electrode, a positive electrode and an ionic conductor using the electrolytic solution material of the present invention as a basic constituent element. An electrode element composed of a positive electrode and a negative electrode is made to contain an electrolytic solution that is an ionic conductor. FIG. 3 shows a schematic cross-sectional view of one embodiment of such an electric double layer capacitor and an enlarged schematic view of the electrode surface.

  The positive electrode and the negative electrode are polarizable electrodes, and are composed of activated carbon fibers, activated carbon particle molded bodies, activated carbon particles such as activated carbon particles, a conductive agent, and a binder material as an electrode active material. It is preferable to use it as a plate-shaped molded body. In the electric double layer capacitor having such a configuration, as shown in the enlarged view of FIG. 3, the electric double layer generated at the interface between the polarizable electrode and the electrolytic solution due to physical adsorption / desorption of ions is charged. Will be stored.

As the activated carbon, those having an average pore diameter of 2.5 nm or less are preferable. The average pore diameter of the activated carbon is preferably measured by the BET method using nitrogen adsorption. The specific surface area of the activated carbon varies depending on the capacitance per unit area (F / m ² ) depending on the carbonaceous species, the decrease in bulk density accompanying the increase in the specific surface area, etc., but the specific surface area determined by the BET method by nitrogen adsorption as is preferably ^{500~2500m 2 / g, 1000~2000m 2 /} g is more preferable.

  As the method for producing the activated carbon, plant-based wood, sawdust, coconut husk, pulp waste liquid, fossil fuel-based coal, heavy petroleum oil, or pyrolyzed coal and petroleum-based pitch, petroleum coke, Carbon aerogel, mesophase carbon, tar pitched fiber, synthetic polymer, phenol resin, furan resin, polyvinyl chloride resin, polyvinylidene chloride resin, polyimide resin, polyamide resin, ion exchange resin, liquid crystal polymer, plastic disposal It is preferable to use an activation method in which a raw material such as a product or a waste tire is carbonized and then activated.

  The activation method includes (1) a gas activation method in which a carbonized raw material is contact-reacted with water vapor, carbon dioxide gas, oxygen, and other oxidizing gas at a high temperature, and (2) zinc chloride and phosphoric acid are added to the carbonized raw material. An inert gas atmosphere that is uniformly impregnated with sodium phosphate, calcium chloride, potassium sulfide, potassium hydroxide, sodium hydroxide, potassium carbonate, sodium carbonate, sodium sulfate, potassium sulfate, calcium carbonate, boric acid, nitric acid, etc. The chemical activation method which heats in and obtains activated carbon by the dehydration and oxidation reaction of a chemical | medical agent is mentioned, Any may be used.

Activated carbon obtained by the above activation method is preferably heat treated at 500 to 2500 ° C., more preferably 700 to 1500 ° C. in an inert gas atmosphere such as nitrogen, argon, helium, xenon, etc. The electron conductivity may be increased by removing functional groups or by developing carbon crystallinity. Examples of the shape of the activated carbon include crushing, granulation, granule, fiber, felt, woven fabric, and sheet shape. In the case of particles, the average particle diameter is preferably 30 μm or less in terms of improving the bulk density of the electrode and reducing the internal resistance.
As the electrode active material, in addition to activated carbon, a carbon material having the above-described high specific surface area may be used. For example, carbon nanotubes or diamond produced by plasma CVD may be used.

  As the conductive agent, carbon black such as acetylene black and ketjen black, natural graphite, thermally expanded graphite, carbon fiber, metal fiber such as ruthenium oxide, titanium oxide, aluminum, and nickel are preferable. These can use 1 type (s) or 2 or more types. Among these, acetylene black and ketjen black are more preferable in that the conductivity is effectively improved with a small amount. The blending amount of the conductive agent varies depending on the bulk density of the activated carbon, but when the activated carbon is 100% by mass, 5 to 50% by mass is preferable, and 10 to 30% by mass is more preferable.

  As the binder material, polytetrafluoroethylene, polyvinylidene fluoride, carboxymethyl cellulose, fluoroolefin copolymer crosslinked polymer, polyvinyl alcohol, polyacrylic acid, polyimide, petroleum pitch, coal pitch, phenol resin, and the like are suitable. These can use 1 type (s) or 2 or more types. The blending amount of the binder substance varies depending on the type and shape of the activated carbon, but when the activated carbon is 100% by mass, 0.5 to 30% by mass is preferable, and 2 to 30% by mass is more preferable.

  The positive electrode and negative electrode are formed by, for example, (1) a method obtained by adding polytetrafluoroethylene to a mixture of activated carbon and acetylene black and then press-molding. (2) activated carbon and pitch, tar, phenol resin, etc. A method of mixing and molding the binder material and then heat-treating it under an inert atmosphere to obtain a sintered body, and (3) a method of sintering only activated carbon and the binder material or activated carbon to form an electrode are preferred. When using activated carbon fiber cloth obtained by activating carbon fiber cloth, it may be used as an electrode as it is without using a binder substance.

In the electric double layer capacitor, the polarizable electrode is prevented from contacting or short-circuiting by a method in which the separator is sandwiched between the polarizable electrodes or a method in which the polarizable electrodes are opposed to each other by using a holding means. Is preferred. As the separator, it is preferable to use a porous thin film that does not cause a chemical reaction with molten salt or the like in the operating temperature range. As the material of the separator, paper, polypropylene, polyethylene, glass fiber, and the like are suitable.
Examples of the shape of the electric double layer capacitor include a coin type, a wound type, a square type, and an aluminum laminate type, and any shape may be used.

  Electrochemical devices such as lithium secondary batteries, electrolytic capacitors, and electric double layer capacitors using the electrolyte material according to the present invention include portable information terminals, portable electronic devices, small household electric power storage devices, motorcycles, electric vehicles, It can be suitably used for various applications such as a hybrid electric vehicle.

The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to these examples. Unless otherwise specified, “part” means “part by weight” and “%” means “mass%”.
In the following examples and comparative examples, the ionic conductivity measurement was performed at 25 ° C., 20 ° C., 0 ° C., −20 ° C., −40 ° C. and −55 ° C. using an SUS electrode and impedance analyzer SI1260 (trade name). ; Manufactured by Solartron Co.) by the complex impedance method. In addition, cyclic Volta down cytometry measurements were carried out as described above.

Reference example 1
An ion conductive material in which ethylmethylimidazolium dicyanoamide (hereinafter referred to as EMImDCA) and methylpropylpyrrolidinium dicyanoamide (hereinafter referred to as MPrPyDCA) were mixed at a mass ratio of 50:50 was obtained. As a result of measuring the ionic conductivity of this ion conductive material, 2.2 × 10 ⁻² S / cm (25 ° C.), 1.0 × 10 ⁻² S / cm (0 ° C.), 4.0 × 10 ^{− 3} S / cm (-20 degreeC) and 1.6 * 10 < ^-4 > S / cm (-55 degreeC) were shown. These results are shown in Table 1.

Example 1, Reference Examples 2-9 and Comparative Examples 1-8
Ionic conductivity was measured in the same manner as in Example 1 except that the composition and mixing ratio were as shown in Table 1. The results are shown in Table 1.

Table 1 will be described below.
EMImDCA: 1-ethyl-3-methylimidazolium dicyanoamide MPrPyDCA: methylpropylpyrrolidinium dicyanoamide MBPyDCA: methylbutylpyrrolidinium dicyanoamide EMImTCM: 1-ethyl-3-methylimidazolium tricyanomethide EMPyDCA: ethylmethylpyrrole Dinium dicyanoamide EMImTFSI: 1-ethyl-3-methylimidazolium bis (trifluoromethanesulfonylimide)
MBPyTFSI: Methylbutylpyrrolidinium bis (trifluoromethanesulfonylimide)
DMEPrADCA: Dimethylethylpropylammonium dicyanoamide DEMEDCA: Diethylmethyl (2-methoxyethyl) ammonium dicyanoamide TMHATFSI: Trimethylhexylammonium bis (trifluoromethanesulfonylimide)
EMImBzt: 1-ethyl-3-methylimidazolium benzoate

Examples 2 to 5, Reference Examples 10 to 14 and Comparative Example 3
The ion conductive material was adjusted to the composition described in Table 2, and the CV on the oxidation side of this ion conductive material was measured. Further, according to the following criteria, to determine the inhibitory effect of the electrolyte degradation by electrostatic position applied. The results are shown in Table 2.
◎: electrostatic position applying high effect of suppressing the electrolyte degradation by (third cycle peak current reduction rate of 60% or more)
○: electrostatic position applied by a slightly higher inhibition effect of the electrolytic solution decomposition (third cycle peak current reduction rate of 20% or more)
×: electrostatic position applied by a low inhibitory effect of electrolyte decomposition (third cycle peak current reduction rate is 5% or more)

Table 2 will be described below.
EMImDCA: 1-ethyl-3-methylimidazolium dicyanoamide EMImTCM: 1-ethyl-3-methylimidazolium tricyanomethide EMImOCN: 1-ethyl-3-methylimidazolium sodium cyanate GBL: γ-butyrolactone EMImTFSI: 1-ethyl -3-Methylimidazolium bis (trifluoromethanesulfonylimide)
* 1 “EMImDCA / TCM (1: 1) / GBL (mixing ratio: 35/65)” means a mixture of EMImDCA and EMImTCM at a mass ratio of 1: 1 and GBL at a mixing ratio of 35/65. It means a mixture.

Claims (4)

An electrolytic solution material containing two or more ionic liquids,
The electrolyte material has at least one imidazolium cation as an essential component,
The following general formula (1);

(Wherein X represents at least one element selected from B, C and N, a is an integer of 1 or more, and d is an integer of 0 or more). It is an electrolyte material that is essential for more than a species ,
An electrolyte solution material, wherein the anion paired with the cation is different . Electrolyte material according to claim 1, wherein the ionic conductivity at -55 ° C. is 1 × ¹⁰ -6 S / cm or more. Potential application in cyclic voltammetry measurement using a glassy carbon electrode as the working electrode, an Ag electrode as the reference electrode, and a platinum electrode as the counter electrode, and a sweep rate of 100 mV / s and a sweep range of from 3 to 3 V in a 30 ° C. atmosphere. When the potential is applied in the third and subsequent cycles, the peak current on the oxidation side in the first cycle is i _p1 , the peak current in the second and subsequent cycles is i _pn, and is obtained by (i _p1 −i _pn ) / i _p1 × 100. electrolyte material according to claim 1 or 2 peak current reduction ratio is a value is equal to or less than 20%. Lithium secondary battery characterized by using an electrolytic solution material according to any one of claims 1 to 3 electrolytic capacitor or electric double layer capacitor.

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