WO2014073378A1

WO2014073378A1 - Electrode protective film forming agent, electrode, electrolyte, lithium secondary battery, lithium-ion capacitor, and method for producing electrode protective film

Info

Publication number: WO2014073378A1
Application number: PCT/JP2013/078694
Authority: WO
Inventors: 拓紀牧野; 順子高田
Original assignee: 三洋化成工業株式会社
Priority date: 2012-11-07
Filing date: 2013-10-23
Publication date: 2014-05-15
Also published as: CN104737340A; JPWO2014073378A1; JP6165162B2; CN104737340B; KR20150068462A; KR101692172B1

Abstract

The purpose of the present invention is to provide: a lithium secondary battery having excellent output characteristics, long-term cycle characteristics, and low electrode resistance; an electrode for a lithium-ion capacitor; and an electrolyte. This electrode protective film forming agent (D) contains a compound (C) having: at least one bond (a) selected from a group comprising a urethane bond (a1), a urea bond (a2), an allophanate bond (a3) and a biuret bond (a4); a polymerizable unsaturated bond (b); and a group (g) represented by general formula (1). [M is a monovalent metal ion, and A represents -CO₂ ^-,-SO₃ ^-, -OPO(OR¹)O^-, -B(O^-)₂, -B(OR²)O^-or -B(OR³)₃ ^- (R¹ to R³ are each a hydrocarbon group with a carbon number of 1 to 10; and there is a plurality of R³, each of which may be the same or different, and may combine with each other to form a ring.)]

Description

Electrode protective film forming agent, electrode, electrolytic solution, lithium secondary battery, lithium ion capacitor, and method for producing electrode protective film

The present invention relates to an electrode protective film forming agent, an electrode, an electrolytic solution, a lithium secondary battery, a lithium ion capacitor, and a method for producing an electrode protective film.

Non-aqueous electrolyte secondary batteries such as lithium secondary batteries are characterized by high voltage and high energy density, and are therefore widely used in the field of portable information devices, and their demand is rapidly expanding. Currently, it has established a position as a standard battery for mobile information devices such as mobile phones and notebook computers. Of course, along with the high performance and multi-functionality of portable devices, etc., even higher performance (for example, higher capacity and higher energy density) for non-aqueous electrolyte secondary batteries as its power source It has been demanded. In order to meet this demand, various methods such as increasing the density by improving the charging rate of the electrodes, increasing the depth of use of the current active material (particularly the negative electrode), and developing a new high-capacity active material have been studied. In reality, the capacity of the non-aqueous electrolyte secondary battery is reliably increased by these methods.

In recent years, there is an urgent need to increase the output of lithium secondary batteries to meet the needs of electric vehicles. Generally, two important factors can be considered for increasing the output of a lithium secondary battery. One is that the electrode material has high electron conductivity, and the other is that lithium ion has high conductivity. When either one is inferior, the internal resistance of the battery becomes high and sufficient output characteristics cannot be obtained. The main cause of the internal resistance is the electrode material where the reaction interface between ion conduction and electron conduction is concentrated.

Among the ionic conduction, the interfacial resistance on the electrode surface has a particularly large resistance. The cause of the interface resistance of the negative electrode is said to be due to the rate-determining step of the desolvation reaction in which the solvent molecules coordinated to the lithium ions are eliminated during the insertion reaction of lithium ions into the negative electrode. . As a method for promoting desolvation in the negative electrode, a method using polyacrylic acid as a binder (Patent Document 1) or a method using azacrown ether has been proposed (Patent Document 2).

JP 2007-287570 A JP 2010-86954 A

However, there is no method for reducing the interface resistance of the positive electrode, and the compound of Patent Document 1 is not sufficient for the effect of reducing the interface resistance of the negative electrode. Further, the compound of Patent Document 2 is not suitable for a positive electrode protective film forming agent because the oxidation stability of azacrown ether itself is not sufficient.

An object of the present invention is to provide an electrode or an electrolytic solution for a lithium secondary battery or a lithium ion capacitor that is excellent in output characteristics and long-term cycle characteristics and has low electrode resistance.

As a result of intensive studies to achieve the above object, the present inventors have reached the present invention. That is, the present invention provides at least one bond (a) selected from the group consisting of urethane bond (a1), urea bond (a2), allophanate bond (a3) and biuret bond (a4), polymerizable unsaturated bond (b ) And an electrode protective film forming agent (D) containing the compound (C) having the group (g) represented by the general formula (1); an electrode or an electrolytic solution containing the electrode protective film forming agent (D); Lithium secondary battery or lithium ion capacitor having the electrode and / or the electrolytic solution; electrode protection including a step of applying a voltage after the electrode protective film forming agent (D) is contained in the electrode and / or the electrolytic solution It is a manufacturing method of a film | membrane.

[M is a monovalent metal ion, and A is —CO ₂ ⁻ , —SO ₃ ⁻ , —OPO (OR ¹ ) O ⁻ , —B (O ⁻ ) ₂ , —B (OR ² ) O ⁻ or — B (OR ³ ) ₃ ^— (R ¹ to R ³ are each a hydrocarbon group having 1 to 10 carbon atoms, and a plurality of R ³ may be the same or different and may form a ring with each other. Good). ]

By using an electrode and / or electrolyte containing the electrode protective film forming agent (D) of the present invention, a lithium secondary battery or a lithium ion capacitor having excellent charge / discharge cycle characteristics and output characteristics and low electrode resistance is produced. it can.

<Electrode protective film forming agent (D)>
The electrode protective film-forming agent (D) of the present invention is contained in the negative electrode, the positive electrode, or both of a lithium secondary battery or a lithium ion capacitor, and then a voltage is applied to the battery or the capacitor. A polymerized film is formed on the surface, and the charge / discharge cycle characteristics and output characteristics can be improved by the action of the polymerized film, and the electrode resistance can be reduced.
Further, after the electrode protective film forming agent (D) is contained in the electrolyte solution of a lithium secondary battery or a lithium ion capacitor, a voltage is applied to the battery or the capacitor to form a polymer film on the surface of the electrode active material. In addition, charge / discharge cycle characteristics and output characteristics can be improved by the action of the polymer film, and electrode resistance can be reduced.

The electrode protective film forming agent (D) of the present invention comprises at least one bond (a) selected from the group consisting of urethane bond (a1), urea bond (a2), allophanate bond (a3) and biuret bond (a4), It contains a compound (C) having a polymerizable unsaturated bond (b) and a group (g) represented by the above general formula (1).

The urethane bond (a1) is a bond represented by —OCONH—,
The urea bond (a2) is a bond represented by -NHCONH-,
The allophanate bond (a3) is a bond represented by the following formula (5):

The biuret bond (a4) is a bond represented by the following formula (6).

The polymerizable unsaturated bond (b) is a carbon-carbon double bond, and examples of the group having the bond include an alkenyl ether group (j1) represented by the following general formula (3) and the following general formula (4). And at least one group (j) selected from the group consisting of an alkenyl group (j2) and a (meth) acryloyloxy group (j3). In the present specification, “(meth) acryloyloxy group” means “acryloyloxy group or methacryloyloxy group”.

[In the formula (3), T ¹ to T ³ are a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. ]

[In Formula (4), T ⁴ to T ⁶ are a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and may form a ring with each other. ]
Among these, the alkenyl group (j2) represented by the general formula (4) is preferable from the viewpoint of the reactivity of the polymerizable group.

Examples of the alkyl group having 1 to 3 carbon atoms include methyl, ethyl, n-propyl, and isopropyl.

Examples of the alkenyl ether group (j1) include vinyloxy group, 1-methylvinyloxy group, 1-propenoxy group, 1-methyl-1-propenoxy group, 2-methyl-1-propenoxy group and 1,2-dimethyl-1- A propenoxy group is mentioned.
Of these, a 1-propenoxy group is preferable from the viewpoint of the reactivity of the polymerizable group.

Examples of the alkenyl group (j2) include a vinyl group, 1-propenyl group, 1-methyl-1-propenyl group, 2-methyl-1-propenyl group, 1,2-dimethyl-1-propenyl group, and general formula (4 ) In which T ⁵ is a methyl group and T ⁴ and T ⁶ form a ring (for example, 1-methyl-1-cyclohexen-2-yl and 2,6,6-trimethylcyclohexen-1-yl, etc.) ).
Among these, from the viewpoint of the reactivity of the polymerizable group, preferred is a polymerizable group in which at least two of T ⁴ to T ⁶ are substituted with an alkyl group having 1 to 3 carbon atoms, and more preferably 2- A methyl-1-propenyl group or a 1,2-dimethyl-1-propenyl group;

In the group (g) represented by the general formula (1), M is a monovalent metal ion, A is —CO ₂ ⁻ , —SO ₃ ⁻ , —OPO (OR ¹ ) O ⁻ , —B (O ^— ) ₂ , —B (OR ² ) O ^— or —B (OR ³ ) ₃ ^— (R ¹ to R ³ are each a hydrocarbon group having 1 to 10 carbon atoms, and a plurality of R ³ may be the same. They may be different and may form a ring with each other.

R ¹ and R ² are a monovalent aliphatic hydrocarbon group having 1 to 10 carbon atoms, a monovalent aromatic hydrocarbon group having 6 to 10 carbon atoms, or a monovalent alicyclic group having 5 to 10 carbon atoms. A hydrocarbon group etc. are mentioned. Among these, a monovalent aliphatic hydrocarbon group and a monovalent alicyclic hydrocarbon group are preferable from the viewpoint of oxidation stability of the compound.

R ³ is a monovalent aliphatic hydrocarbon group having 1 to 10 carbon atoms, a monovalent aromatic hydrocarbon group having 6 to 10 carbon atoms, or a monovalent alicyclic hydrocarbon group having 5 to 10 carbon atoms. And a residue obtained by removing two hydroxyl groups from an aliphatic diol having 2 to 10 carbon atoms or a residue obtained by removing three hydroxyl groups from an aliphatic triol having 4 to 10 carbon atoms. Among these, preferred from the viewpoint of oxidative stability of the compound are monovalent aliphatic hydrocarbon groups, monovalent alicyclic hydrocarbon groups, residues obtained by removing two hydroxyl groups from aliphatic diols, or fatty acids. It is a residue obtained by removing three hydroxyl groups from a group triol.

Among A, —SO ₃ ^— is preferable from the viewpoint of charge / discharge cycle characteristics.

Examples of monovalent metal ions in M include lithium ions, sodium ions, potassium ions, rubidium ions, and cesium ions.
Among these, lithium ions or sodium ions are preferable from the viewpoint of output characteristics.

Examples of the compound (C) include a compound represented by the following general formula (2).

Y is an (s + t) -valent hydrocarbon group having 2 to 42 carbon atoms (Y1), which may contain at least one atom selected from the group consisting of an oxygen atom, a sulfur atom and a nitrogen atom; A divalent residue (Y2) obtained by removing two isocyanate groups from a urethane prepolymer having isocyanate groups at both ends, which is a reaction product of diisocyanate (B) and diol (N) having 2 to 20 carbon atoms, allophanate bond A diisocyanate having 11 to 131 carbon atoms having a residue (Y3) or biuret bond (a4) obtained by removing (s + t) isocyanate groups from a diisocyanate (B) modified product having 9 to 118 carbon atoms having (a3) and having (a3) ) Residue (Y4) obtained by removing (s + t) isocyanate groups from the modified product.
s is an integer of 1 to 5, and t is an integer of 1 to 5. (A5) is a urethane bond or a urea bond. R ⁷ is a divalent hydrocarbon group having 1 to 12 carbon atoms, R ⁸ is a monovalent hydrocarbon group having a polymerizable unsaturated bond (b) having 2 to 30 carbon atoms, and (g) is the above general formula ( It is group represented by 1).

The hydrocarbon group (Y1) is a (s + t) valent hydrocarbon group having 2 to 42 carbon atoms, which may contain at least one atom selected from the group consisting of an oxygen atom, a sulfur atom and a nitrogen atom, A divalent hydrocarbon group having 6 to 13 carbon atoms is preferred. Specific examples include divalent aliphatic hydrocarbon groups (ethylene, tetramethylene, hexamethylene, octamethylene, decamethylene, 1-methyltetramethylene, 2-methyltetramethylene), divalent alicyclic hydrocarbon groups ( 1,5,5-trimethyl-cyclohexane-1,3-diyl, methylenedicyclohexyl-4,4'-diyl, cyclohexane-1,4-diyl, 1,4-dimethylene-cyclohexane (from 1,4-cyclohexanedimethanol 2) a divalent aromatic hydrocarbon group (toluene-2,4-diyl, toluene-2,6-diyl, methylenediphenyl-4,4′-diyl, xylylene, tetra A trivalent hydrocarbon group having 9 to 42 carbon atoms, including methylxylylene, phenylene, 1,5-naphthylene) and isocyanurate groups And the like, from the viewpoint of oxidation stability of the compounds, preferred are a divalent aliphatic hydrocarbon group and a divalent alicyclic hydrocarbon group.

Residue (Y2) consists of two isocyanate groups from a urethane prepolymer having isocyanate groups at both ends obtained by reaction of a diisocyanate (B) having 4 to 44 carbon atoms and a diol (N) having 2 to 20 carbon atoms. It is a residue excluding.
Examples of the diisocyanate (B) include diisocyanates obtained by adding two isocyanate groups to the divalent hydrocarbon group (Y1).
Diol (N) includes divalent aliphatic diols (ethylene glycol, tetramethylene glycol, hexamethylene glycol, 1,3-propanediol, 1,5-pentanediol, 1,8-octanediol, 1,10- Decanediol, propylene glycol, 1,3-butanediol, etc.) Divalent alicyclic hydrocarbon group (1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, etc.) Etc.
The number average molecular weight of the urethane prepolymer is preferably 700 to 4800, and more preferably 1000 to 3000.

The residue (Y3) is a residue obtained by removing (s + t) isocyanate groups from a diisocyanate (B) modified product having 9 to 118 carbon atoms having an allophanate bond (a3).
Examples of the modified diisocyanate (B) having 9 to 118 carbon atoms having an allophanate bond (a3) include compounds represented by the following general formula (7).

[In Formula (7), R ⁴ is a divalent group in the hydrocarbon group (Y1), and a plurality of R ⁴ may be the same or different. R ⁵ is a hydrocarbon group having 1 to 20 carbon atoms. ]

R ⁵ is a linear or branched monovalent aliphatic hydrocarbon group having 1 to 20 carbon atoms (methyl, ethyl, n-propyl, isopropyl, n-butyl, 1-methylpropyl, isobutyl, t-butyl, n-pentyl, isopentyl, 1-methylbutyl, 2-methylbutyl, 1,1-dimethylpropyl, 2,2-dimethylpropyl, 1,2-dimethylpropyl, 1-ethylpropyl, n-hexyl, isohexyl, 3-methylpentyl 2-methylpentyl, 1-methylpentyl, 1,1-dimethylbutyl, 2,2-dimethylbutyl, 1,1,2-trimethylpropyl, 1-ethyl-1-methylpropyl, heptyl, octyl, isooctyl, 2 -Ethylhexyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, Xadecyl, heptadecyl, octadecyl, nonadecyl, icosyl) and monovalent alicyclic hydrocarbon groups having 5 to 20 carbon atoms (cyclopentyl, cyclohexyl, cyclohexylmethyl, cyclohexylethyl).

The residue (Y4) is a residue obtained by removing (s + t) isocyanate groups from a modified diisocyanate (B) having 11 to 131 carbon atoms having a biuret bond (a4).
Examples of the modified diisocyanate (B) having 11 to 131 carbon atoms having a biuret bond (a4) include compounds represented by the following general formula (8).

[In Formula (8), R ⁶ is a divalent group in the hydrocarbon group (Y1), and a plurality of R ⁶ may be the same or different. ]

In the general formula (2), s is an integer of 1 to 5, preferably an integer of 1 to 3. In the general formula (2), t is an integer of 1 to 5, preferably an integer of 1 to 3. The sum of these s and t is an integer of 2 to 10, preferably an integer of 2 to 6.
In the general formula (2), (a5) is a urethane bond or a urea bond. Two or more (a5) s may be urethane bonds, all urea bonds, or both urethane bonds and urea bonds, but all are preferably urethane bonds.

In the above general formula (2), R ⁸ is a monovalent hydrocarbon group having 2 to 30 carbon atoms and having a polymerizable unsaturated bond (b).
R ⁸ is a linear or branched monovalent hydrocarbon group having 2 to 30 carbon atoms (residue obtained by removing a hydroxyl group from an unsaturated alcohol such as vinyl alcohol, citronellol, linalool, prenol or geraniol), carbon number 5 To 30 monovalent unsaturated alicyclic hydrocarbon groups (residues obtained by removing hydroxyl groups from unsaturated alicyclic alcohols such as retinol).
Citronellol, linalool, prenol and geraniol are preferred from the viewpoint of reactivity.

In the general formula (2), R ⁷ is a divalent hydrocarbon group having 1 to 12 carbon atoms.
R ⁷ is a linear or branched divalent aliphatic hydrocarbon group having 1 to 12 carbon atoms (methylene, ethylene, trimethylene, ethylidene, tetramethylene, 1-methyltrimethylene, 2-methyltrimethylene, 1-ethyl Ethylene, 1,1-dimethylethylene, ethylmethylmethylene, propylmethylene, pentamethylene, 1-methyltetramethylene, 2-methyltetramethylene, 1,1-dimethyltrimethylene, 2,2-dimethyltrimethylene, 1,2 -Dimethyltrimethylene, 1,3-dimethyltrimethylene, 1-ethyltrimethylene, 1,1,2-trimethylethylene, diethylmethylene, 1-propylethylene, butylmethylene, hexamethylene, 1-methylpentamethylene, 1, 1-dimethyltetramethylene, 2,2-dimethyltetramethyle 1,1,3-trimethyltrimethylene, 1,1,2-trimethyltrimethylene, 1,1,2,2-tetramethylethylene, 1,1-dimethyl-2-ethylethylene, 1,1-diethyl Ethylene, 1-propyltrimethylene, 2-propyltrimethylene, 1-butylethylene, 1-methyl-1-propylethylene, 1-methyl-2-propylethylene, pentylmethylene, butylmethylmethylene, ethylpropylmethylene, 1- Methyl-1-vinyl-1,3-propanediyl, 3-methyl-pentane-1,5-diyl or 3,7-dimethylnona-2,4,6,8-tetraene-1,9-diyl), carbon number 5 to 12 divalent alicyclic hydrocarbon groups (1,2-cyclopentylene, 1,2-cyclohexylene, 1,3-cyclohexylene, 1,4- Chlohexylene, a residue obtained by removing two hydroxyl groups from 1,3-cyclohexanedimethanol, a residue obtained by removing two hydroxyl groups from 1,4-cyclohexanedimethanol, and 1-hydroxy-3-hydroxymethylcyclohexane A residue obtained by removing two hydroxyl groups, a residue obtained by removing two hydroxyl groups from 1-hydroxy-4-hydroxymethylcyclohexane, a residue obtained by removing two hydroxyl groups from 1,4-cyclohexanediethanol, or 1,4 A residue obtained by removing two hydroxyl groups from cyclohexanedipropanol), a divalent aromatic hydrocarbon group having 6 to 12 carbon atoms (1,2-phenylene, 1,3-phenylene, 1,4-phenylene, 2 , 4-tolylene, 2,5-tolylene or 1,5-naphthylene).

The concentration of the bond (a) in the compound (C) is preferably 0.2 to 10 mmol / g, more preferably 0.5 to 5 mmol / g.

The concentration of the polymerizable unsaturated bond (b) in the compound (C) is preferably 0.2 to 10 mmol / g, more preferably 0.2 to 5 mmol / g.

The number average molecular weight of the compound (C) is preferably 238 to 5000, more preferably 450 to 3500. The number average molecular weight (Mn) of the compound (C) can be measured using gel permeation chromatography (hereinafter referred to as GPC). As the measurement conditions for GPC, the measurement conditions for the number average molecular weight (Mn) of the compounds (C-5) and (C-6) according to Examples 5 and 6 described later can be used. Furthermore, the molecular weight can be measured with a mass spectrometer or calculated from the structural formula.

Compound (C) can be obtained, for example, by the following method.
(1) having a compound (B1) having two or more isocyanate groups, an active hydrogen compound (L) having a polymerizable unsaturated bond (b), and a group (g) represented by the general formula (1) It is synthesized by reacting with an active hydrogen compound (G1).
Alternatively, the compound (B1) having two or more isocyanate groups, the active hydrogen compound (L) having a polymerizable unsaturated bond (b), -CO ₂ H, -SO ₃ H, -OPO (OR ¹ ) OH, —B (OH) ₂ or —B (OR ² ) OH (R ¹ and R ² are each a hydrocarbon group having 1 to 10 carbon atoms) and an active hydrogen compound (G2) having a group represented by After reacting, it is synthesized by neutralizing with a monovalent metal hydroxide.
(2) In the above (1), instead of the compound (B1) having two or more isocyanate groups, at least one bond (a) selected from the group consisting of allophanate bond (a3) and biuret bond (a4) is used. The compound (B2) having two or more isocyanate groups is synthesized.
(3) In the above (1), instead of the compound (B1) having two or more isocyanate groups, a reaction product of a diisocyanate (B) having 4 to 44 carbon atoms and a diol (N) having 2 to 20 carbon atoms is used. It is synthesized using a urethane prepolymer (B3) having a certain terminal isocyanate group.

The above reactions (1) to (3) are preferably carried out in the presence of a urethanization catalyst from the viewpoint of shortening the reaction time.
The reaction is carried out without using a solvent or in a solvent. Examples of the reaction solvent include N-methylpyrrolidone, dimethylformamide, dioxolane and the like, and N-methylpyrrolidone is preferable.
The reaction time is 1 to 24 hours, but 5 to 8 hours are preferable.
The order of preparation may be that the active hydrogen compound is charged first, or the compound having an isocyanate group may be charged first.
The molar ratio is preferably reacted with a total of 1 to 1.5 equivalents of hydroxy group or amino group with respect to the isocyanate group so as not to leave an isocyanate group.

Examples of the compound (B1) include dicyclohexylmethane-4,4′-diisocyanate, hexamethylene diisocyanate, 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate, and the like.
Examples of the compound (B2) include DURANATE A201H (allophanate-modified hexamethylene diisocyanate) [manufactured by Asahi Kasei Chemicals Corporation], DURANATE 24A-100 (biuret-modified hexamethylene diisocyanate) [manufactured by Asahi Kasei Chemicals Corporation], and the like. Examples of the compound (B3) include a urethane prepolymer obtained by reacting dicyclohexylmethane-4,4′-diisocyanate with 1,4-cyclohexanedimethanol.

Examples of the active hydrogen compound (L) having a polymerizable unsaturated bond (b) include 1-hydroxymethyl-4- (1-propenoxymethyl) cyclohexane, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, Examples include linalool, citronellol, retinol, prenol and the like.

Examples of the active hydrogen compound (G1) having the group (g) represented by the general formula (1) include lithium isethionate, sodium isethionate, lithium lactate, sodium lactate, lithium 2-aminoethanesulfonate, 2- Examples include sodium aminoethanesulfonate, lithium 4-hydroxyphenylboronate, lithium 4- (hydroxymethyl) phenylboronate, lithium (3-aminophenyl) cyclic triol borate and the like.

—CO ₂ H, —SO ₃ H, —OPO (OR ¹ ) OH, —B (OH) ₂ or —B (OR ² ) OH (R ¹ and R ² are each a hydrocarbon group having 1 to 10 carbon atoms) Examples of the active hydrogen compound (G2) having a group represented by formula (I) include isethionic acid, taurine, lactic acid, glycolic acid, 4-hydroxyphenylboronic acid, 4- (hydroxymethyl) phenylboronic acid, and the like.

Examples of the diol (N) include 1,4-butanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,4-cyclohexanedimethanol, 1,4-cyclohexanediethanol, and the like. Can be mentioned.

The electrode protective film forming agent (D) may contain a component other than the compound (C), but preferably does not contain any component other than the compound (C). Examples of components other than the compound (C) include vinylene carbonate, fluoroethylene carbonate, chloroethylene carbonate, ethylene sulfite, propylene sulfite, and α-bromo-γ-butyrolactone.
The content of the compound (C) in the electrode protective film forming agent (D) is preferably 10 to 100% by weight, more preferably 50 to 100% by weight, based on the weight of the electrode protective film forming agent (D). %.

<Electrode>
The electrode of the present invention contains an electrode protective film forming agent (D), an active material (H), and a binder (K) before charging and discharging. While charging / discharging is started, a part of the electrode protective film forming agent (D) undergoes a polymerization reaction to form a polymer on the surface of the active material (H). At this time, the electrode of the present invention comprises an unreacted electrode protective film forming agent (D), an active material (H) having an electrode protective film made of a polymer of (D) on the surface, and a binder ( K).

A negative electrode for a lithium secondary battery is obtained by using the negative electrode active material (H1) as the active material (H), and a negative electrode for a lithium ion capacitor is obtained by doping lithium into (H1). Moreover, the positive electrode active material (H2) for lithium secondary batteries and the positive electrode active material (H3) for lithium ion capacitors are mentioned.
Examples of the negative electrode active material (H1) include graphite, amorphous carbon, polymer compound fired bodies (for example, those obtained by firing and carbonizing phenol resin and furan resin, etc.), cokes (for example, pitch coke, needle coke, and petroleum coke), And carbon fibers, conductive polymers (for example, polyacetylene and polypyrrole), tin, silicon, and metal alloys (for example, lithium-tin alloy, lithium-silicon alloy, lithium-aluminum alloy, and lithium-aluminum-manganese alloy). .
Examples of the positive electrode active material (H2) for the lithium secondary battery include composite oxides of lithium and transition metals (for example, LiCoO ₂ , LiNiO ₂ , LiMnO ₂ and LiMn ₂ O ₄ ), transition metal oxides (for example, MnO ₂ and V _2). O ₅ ), transition metal sulfides (eg, MoS ₂ and TiS ₂ ), and conductive polymers (eg, polyaniline, polyvinylidene fluoride, polypyrrole, polythiophene, polyacetylene, poly-p-phenylene, and polycarbazole).
Examples of the positive electrode active material (H3) for a lithium ion capacitor include activated carbon, carbon fiber, and a conductive polymer (for example, polyacetylene and polypyrrole).

Examples of the binder (K) include polymer compounds such as starch, polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose, polyvinyl pyrrolidone, tetrafluoroethylene, polyethylene, and polypropylene.

The electrode of the present invention can further contain a conductive additive (J).
As the conductive assistant (J), graphite (for example, natural graphite and artificial graphite), carbon blacks (for example, carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black and thermal black) and metal powder (for example, Aluminum powder and nickel powder), conductive metal oxides (for example, zinc oxide and titanium oxide), and the like.

Electrode protective film forming agent (D), active material (H), binder based on total weight of electrode protective film forming agent (D), active material (H) and binder (K) in the electrode of the present invention The preferred contents of (K) and the conductive additive (J) are as follows.
The content of the electrode protective film forming agent (D) is preferably 0.1 to 5% by weight, more preferably 0.2 to 2% by weight, from the viewpoint of charge / discharge cycle characteristics.
The content of the active material (H) is preferably 70 to 98% by weight, more preferably 90 to 98% by weight, from the viewpoint of battery capacity.
The content of the binder (K) is preferably 0.1 to 29% by weight and more preferably 0.5 to 10% by weight from the viewpoint of battery capacity.
The content of the conductive auxiliary agent (J) is preferably 0 to 29% by weight, more preferably 1 to 10% by weight from the viewpoint of battery output.

The electrode of the present invention comprises, for example, an electrode protective film forming agent (D), an active material (H), a binder (K), and optionally a conductive assistant (J) in 30 to 60% by weight in water or a solvent. A slurry dispersed at a concentration is applied to a current collector with a coating device such as a bar coater, dried to remove the solvent, and, if necessary, obtained by pressing with a press.

As the solvent, lactam compounds, ketone compounds, amide compounds, amine compounds, cyclic ether compounds and the like can be used.
Examples thereof include 1-methyl-2-pyrrolidone, methyl ethyl ketone, dimethylformamide, dimethylacetamide, N, N-dimethylaminopropylamine and tetrahydrofuran (THF).
Examples of the current collector include copper, aluminum, titanium, stainless steel, nickel, baked carbon, a conductive polymer, and conductive glass.

The electrolytic solution of the present invention contains an electrode protective film forming agent (D), an electrolyte (E) and a non-aqueous solvent (F), and is preferably useful as an electrolytic solution for lithium secondary batteries and lithium ion capacitors. .
The electrolytic solution of the present invention contains an electrode protective film forming agent (D), an electrolyte (E), and a nonaqueous solvent (F) before charging and discharging. While charging / discharging is started, a part of the electrode protective film forming agent (D) undergoes a polymerization reaction to form a polymer film on the surface of the active material (H) constituting the electrode. As the polymerization reaction proceeds, the electrode protective film forming agent (D) in the electrolytic solution of the present invention decreases.

The electrolyte (E), normal is can be used such as those used in the electrolytic solution, for _{_{_{example, LiPF 6, LiBF 4, LiSbF}}} 6, LiAsF 6 and LiClO ₄ lithium salts of inorganic acids such as, LiN (CF ₃ Examples include lithium salts of organic acids such as SO ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) ₂ and LiC (CF ₃ SO ₂ ) ₃ . Among these, LiPF ₆ is preferable from the viewpoint of battery output and charge / discharge cycle characteristics.

As the non-aqueous solvent (F), those used in ordinary electrolytic solutions can be used, for example, lactone compounds, cyclic or chain carbonates, chain carboxylates, cyclic or chain ethers, phosphoric acid Esters, nitrile compounds, amide compounds, sulfones, sulfolanes, and the like and mixtures thereof can be used.

Of the non-aqueous solvents (F), cyclic or chain carbonates are preferred from the viewpoint of battery output and charge / discharge cycle characteristics.
Specific examples of the cyclic carbonate include propylene carbonate, ethylene carbonate, butylene carbonate, and the like.
Specific examples of the chain carbonate include dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, methyl-n-propyl carbonate, ethyl-n-propyl carbonate, and di-n-propyl carbonate.

Electrode protective film-forming agent (D), electrolyte (E) and non-aqueous solvent (F) based on the total weight of electrode protective film-forming agent (D), electrolyte (E) and non-aqueous solvent (F) in the electrolytic solution of the present invention ) Are preferably as follows.

The content of the electrode protective film forming agent (D) is preferably 0.01 to 10% by weight, more preferably 0.05 to 1% by weight, from the viewpoints of charge / discharge cycle characteristics, battery capacity and high-temperature storage characteristics. .
The content of the electrolyte (E) in the electrolytic solution is preferably 0.1 to 30% by weight, more preferably 0.5 to 20% by weight from the viewpoint of battery output and charge / discharge cycle characteristics.
The content of the non-aqueous solvent (F) is preferably 60 to 99% by weight, more preferably 85 to 95% by weight from the viewpoint of battery output and charge / discharge cycle characteristics.

The electrolytic solution of the present invention may further contain additives such as an overcharge inhibitor, a dehydrating agent and a capacity stabilizer. The content of each component of the following additives is based on the total weight of the electrode protective film forming agent (D), the electrolyte (E), and the nonaqueous solvent (F).
Examples of the overcharge inhibitor include biphenyl, alkylbiphenyl, terphenyl, partially hydrogenated terphenyl, aromatic compounds such as cyclohexylbenzene, t-butylbenzene and t-amylbenzene. The amount of the overcharge inhibitor used is usually 0 to 5% by weight, preferably 0.5 to 3% by weight.

Examples of the dehydrating agent include zeolite, silica gel and calcium oxide. The amount of the dehydrating agent used is usually 0 to 5% by weight, preferably 0.5 to 3% by weight, based on the total weight of the electrolytic solution.

Examples of the capacity stabilizer include fluoroethylene carbonate, succinic anhydride, 1-methyl-2-piperidone, heptane and fluorobenzene. The amount of the capacity stabilizer used is usually 0 to 5% by weight, preferably 0.5 to 3% by weight, based on the total weight of the electrolytic solution.

The lithium secondary battery of the present invention uses the electrode of the present invention as a positive electrode or a negative electrode when the electrolytic solution is injected into a battery can containing a positive electrode, a negative electrode, and a separator, and the battery can be sealed. The electrolytic solution of the present invention is used, or it can be obtained by a combination thereof.

As a separator in a lithium secondary battery, a microporous film made of polyethylene or polypropylene film, a multilayer film of porous polyethylene film and polypropylene, a nonwoven fabric made of polyester fiber, aramid fiber, glass fiber, etc., and silica on these surfaces, The thing to which ceramic fine particles, such as an alumina and titania, were made to adhere is mentioned.

As the battery can in the lithium secondary battery, metal materials such as stainless steel, iron, aluminum and nickel-plated steel can be used, but plastic materials can also be used depending on the battery application. Further, the battery can can be formed into a cylindrical shape, a coin shape, a square shape, or any other shape depending on the application.

The lithium ion capacitor of the present invention can be obtained by replacing the positive electrode with a positive electrode for a lithium ion capacitor and replacing the battery can with a capacitor can in the basic configuration of the lithium secondary battery of the present invention. Examples of the material and shape of the capacitor can include the same as those exemplified for the battery can.

As a method for producing the electrode protective film of the present invention, the electrode of the present invention is used as a positive electrode or a negative electrode, the electrolytic solution of the present invention is used as an electrolytic solution, or a voltage is applied to a combination thereof. There is a way to make it.

Hereinafter, the present invention will be further described with reference to examples, but the present invention is not limited thereto. Hereinafter, unless otherwise specified, “%” represents “% by weight” and “parts” represents “parts by weight”.

The number average molecular weights (Mn) of compounds (C-5) and (C-6) according to Examples 5 and 6 described later were measured using GPC under the following conditions.
Apparatus (example): HLC-8120 manufactured by Tosoh Corporation
Column (example): Tosoh Co., Ltd. TSK GEL GMH6 2 Measurement temperature: 40 degreeC
Sample solution: 0.25 wt% THF solution Solution injection amount: 100 μl
Detection device: Refractive index detector Reference material: Standard polystyrene (TSK standard POLYSTYRENE) 12 points (Mw 500 1050 2800 5970 9100 18100 37900 96400 190000 355000 1890000 2890000) manufactured by Tosoh Corporation

<Production Example 1>
Synthesis of 1-hydroxymethyl-4- (1-propenoxymethyl) cyclohexane;
In a flask equipped with a stirrer, a thermometer, and a cooling tube, 9.86 parts of 1,4-cyclohexanedimethanol (Tokyo Chemical Industry Co., Ltd.) and allyl chloride (Tokyo Chemical Industry Co., Ltd.) 5.76 parts , Sodium hydroxide [Wako Pure Chemical Industries, Ltd.] 6.00 parts and toluene [Wako Pure Chemical Industries, Ltd.] 100 parts were charged and dissolved uniformly with stirring, then at room temperature for 15 minutes. After stirring, 1.32 parts of tetrabutylammonium bromide [manufactured by Wako Pure Chemical Industries, Ltd.] was added. The temperature was raised to 65 ° C. over 2 hours and further stirred for 4 hours to carry out an etherification reaction and a rearrangement reaction. After allowing to cool, 200 parts of water was added and the aqueous layer was separated. Further, the organic layer was washed with 200 parts of water. After removing toluene under reduced pressure (1.3 kPa), the reaction product was purified by an alumina column [150 mesh, Blockman 1, standard grade, manufactured by Sigma-Aldrich] using hexane [manufactured by Wako Pure Chemical Industries, Ltd.] as a solvent, 9.0 parts of 1-hydroxymethyl-4- (1-propenoxymethyl) cyclohexane (L-1) represented by the following formula was obtained (yield 71%).

<Production Example 2>
Lithium isethionate A flask equipped with a stirrer and thermometer was charged with 5.0 parts of a 70% 2-hydroxyethanesulfonic acid solution [manufactured by Wako Pure Chemical Industries, Ltd.] and cooled in an ice bath while lithium hydroxide [Wako Pure Chemical Industries, Ltd.] Neutralized with an aqueous solution containing 0.66 parts. The obtained aqueous solution was heated to evaporate water, and then dried under reduced pressure (1.3 kPa) to obtain 3.6 parts of lithium isethionate (G1-1) (yield 98%).

<Production Example 3>
4-hydroxyphenylboronic acid lithium A flask equipped with a stirrer and a thermometer was charged with 5.0 parts of 4-hydroxyphenylboronic acid [manufactured by Tokyo Chemical Industry Co., Ltd.] and 300 parts of THF while cooling in an ice bath. Neutralization was performed using 0.58 parts of lithium hydride [Wako Pure Chemical Industries, Ltd.]. The THF was removed under reduced pressure (1.3 kPa) to obtain 5.3 parts of lithium 4-hydroxyphenylboronate (G1-2) represented by the following formula (97%).

<Production Example 4>
(3-Aminophenyl) cyclic triol borate lithium salt In a flask equipped with a stirrer, thermometer and Dean-Stark tube, 5.0 parts of 3-aminophenylboronic acid [manufactured by Wako Pure Chemical Industries, Ltd.], trimethylol 4.4 parts of ethane [manufactured by Tokyo Chemical Industry Co., Ltd.] and 64 parts of toluene were charged and heated at 115 ° C. for 8 hours. After removing toluene under reduced pressure (1.3 kPa), 160 parts of THF was charged, and a THF solution containing 0.29 parts of lithium hydride was added dropwise while cooling in an ice bath. After stirring the reaction solution at room temperature for 8 hours, the solvent was distilled off under reduced pressure (1.3 kPa) to give a (3-aminophenyl) cyclic triol borate lithium salt (G1-3) 6.8 represented by the following formula. Parts were obtained (82%).

<Example 1>
Electrode protective film forming agent (D-1)
In a flask equipped with a stirrer, a thermometer and a condenser tube, 8.5 parts of lithium isethionate (G1-1), dicyclohexylmethane-4,4′-diisocyanate [manufactured by Wako Pure Chemical Industries, Ltd.] 15.3 parts 9.9 parts of linalool [manufactured by Wako Pure Chemical Industries, Ltd.], 100 parts of 1-methyl-2-pyrrolidone [manufactured by Tokyo Chemical Industry Co., Ltd.] and dibutyltin dilaurate [manufactured by Tokyo Chemical Industry Co., Ltd.] 07 parts were charged and heated at 80 ° C. for 8 hours. After allowing to cool to room temperature, the reaction product was suspended in hexane and purified by filtration to obtain 10.9 parts of compound (C-1) represented by the following formula (yield 34%). The compound (C-1) is used as an electrode protective film forming agent (D-1).

<Example 2>
Electrode protective film forming agent (D-2)
Example 1 was used except that 11.8 parts of hexamethylene diisocyanate [hexamethylene diisocyanate manufactured by Wako Pure Chemical Industries, Ltd.] was used instead of 15.3 parts of dicyclohexylmethane-4,4′-diisocyanate. 9.6 parts of compound (C-2) represented by the following formula was obtained (yield 36%). The compound (C-2) is referred to as an electrode protective film forming agent (D-2).

<Example 3>
Electrode protective film forming agent (D-3)
Other than using 13.0 parts of 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate [manufactured by Wako Pure Chemical Industries, Ltd.] instead of 15.3 parts of dicyclohexylmethane-4,4′-diisocyanate Was carried out in the same manner as in Example 1 to obtain 11.9 parts of the compound (C-3) represented by the following formula (yield 40%). The compound (C-3) is used as an electrode protective film forming agent (D-3).

<Example 4>
Electrode protective film forming agent (D-4)
The same procedure as in Example 1 was carried out except that 11.8 parts of 1-hydroxymethyl-4- (1-propenoxymethyl) cyclohexane (L-1) was used instead of 9.9 parts of linalool. 13.8 parts of the compound (C-4) shown were obtained (41% yield). The compound (C-4) is used as an electrode protective film forming agent (D-4).

<Example 5>
Electrode protective film forming agent (D-5)
In a flask equipped with a stirrer, a thermometer and a condenser, 46.0 parts of dicyclohexylmethane-4,4′-diisocyanate, 16.8 parts of 1,4-cyclohexanedimethanol [manufactured by Wako Pure Chemical Industries, Ltd.] Charge 100 parts of N-methylpyrrolidone and 0.07 part of dibutyltin dilaurate and heat at 80 ° C. for 8 hours, then add 8.5 parts of lithium 2-hydroxysulfonate and 9.9 parts of linalool, and further heat at 80 ° C. for 8 hours. did. Purification was performed in the same manner as in Example 1 to obtain 18.3 parts of the compound (C-5) represented by the following formula (yield: 23%). [Mn: 1400]. The compound (C-5) is used as an electrode protective film forming agent (D-5).

[Wherein X represents methylenedicyclohexyl-4,4′-diyl. ]

<Example 6>
Electrode protective film forming agent (D-6)
Dicyclohexylmethane-4,4'-diisocyanate instead of 46.0 parts dicyclohexylmethane-4,4'-diisocyanate 117.4 parts, 1,4-cyclohexanedimethanol instead of 16.8 parts 1,4-cyclohexanedi 39.9 parts of compound (C-6) was obtained in the same manner as in Example 5 except that 56.1 parts of methanol was used (yield 21%). [Mn: 3300]. The compound (C-6) is used as an electrode protective film forming agent (D-6).

<Example 7>
Electrode protective film forming agent (D-7)
Example 1 was repeated except that 28.7 parts of duranate A201H (allophanate-modified hexamethylene diisocyanate) [manufactured by Asahi Kasei Chemicals Corporation] was used instead of 15.3 parts of dicyclohexylmethane-4,4′-diisocyanate. As a result, 20.4 parts of urethane compound (C-7) having an allophanate bond was obtained (yield 45%). The compound (C-7) is used as an electrode protective film forming agent (D-7).

<Example 8>
Electrode protective film forming agent (D-8)
Instead of 15.3 parts of dicyclohexylmethane-4,4′-diisocyanate, 27.9 parts of duranate 24A-100 (biuret-modified hexamethylene diisocyanate) [manufactured by Asahi Kasei Chemicals Co., Ltd.] were used, and instead of 9.9 parts of linalool. In addition, 19.8 parts of a urethane compound (C-8) having a biuret bond was obtained in the same manner as in Example 1 except that 19.8 parts of linalool was used (yield 37%). The compound (C-8) is used as an electrode protective film forming agent (D-8).

<Example 9>
Electrode protective film forming agent (D-9)
A compound represented by the following formula (C-9) was prepared in the same manner as in Example 1 except that 9.5 parts of sodium isethionate [manufactured by Wako Pure Chemical Industries, Ltd.] was used instead of 8.5 parts of lithium isethionate. ) 12.5 parts was obtained (38% yield). The compound (C-9) is used as an electrode protective film forming agent (D-9).

<Example 10>
Electrode protective film forming agent (D-10)
Instead of 8.5 parts of lithium isethionate, 8.0 parts of taurine [manufactured by Wako Pure Chemical Industries, Ltd.] was used, and the reaction and purification were carried out in the same manner as in Example 1, followed by methanol [Wako Pure Chemical Industries, Ltd.] Suspended in [manufactured by Co., Ltd.] and neutralized with 1 equivalent of lithium hydroxide [Wako Pure Chemical Industries, Ltd.]. Methanol was removed under reduced pressure (1.3 kPa) to obtain 10.2 parts of compound (C-10) represented by the following formula (yield 32%). The compound (C-10) is used as an electrode protective film forming agent (D-10).

<Example 11>
Electrode protective film forming agent (D-11)
A compound represented by the following formula (C-11) was prepared in the same manner as in Example 1 except that 7.5 parts of 2-hydroxyethyl acrylate [manufactured by Wako Pure Chemical Industries, Ltd.] was used instead of 9.9 parts of linalool. ) 10.7 parts were obtained (yield 36%). Compound (C-11) is referred to as an electrode protective film forming agent (D-11).

<Example 12>
Electrode protective film forming agent (D-12)
A compound represented by the following formula was reacted, neutralized and purified in the same manner as in Example 10 except that 5.8 parts of lactic acid [Wako Pure Chemical Industries, Ltd.] was used instead of 8.0 parts of taurine. C-12) 14.7 parts were obtained (yield 52%). The compound (C-12) is used as an electrode protective film forming agent (D-12).

<Example 13>
Electrode protective film forming agent (D-13)
Compound (C-13) 14.8 represented by the following formula was carried out in the same manner as in Example 1 except that 10.0 parts of citronellol [manufactured by Wako Pure Chemical Industries, Ltd.] was used instead of 9.9 parts of linalool. Parts were obtained (yield 46%). The compound (C-13) is used as an electrode protective film forming agent (D-13).

<Example 14>
Electrode protective film forming agent (D-14)
This was performed in the same manner as in Example 1 except that 5.5 parts of prenol [3-methyl-2-buten-1-ol manufactured by Tokyo Chemical Industry Co., Ltd.] was used instead of 9.9 parts of linalool. Of the compound (C-14) (43% yield). Compound (C-14) is referred to as electrode protective film forming agent (D-14).

Electrode protective film forming agent (D-15)
The compound represented by the following formula (C-15) was prepared in the same manner as in Example 14 except that 9.6 parts of lithium 4-hydroxyphenylboronate (G1-1) was used instead of 9.9 parts of lithium isethionate. 18.7 parts were obtained (yield 30%). The compound (C-15) is used as an electrode protective film forming agent (D-15).

Electrode protective film forming agent (D-16)
A compound represented by the following formula, which was prepared in the same manner as in Example 14 except that 14.6 parts of (3-aminophenyl) cyclic triol borate lithium salt (G1-2) was used instead of 9.9 parts of lithium isethionate ( C-16) 9.1 parts were obtained (yield 27%). The compound (C-16) is used as an electrode protective film forming agent (D-16).

<Comparative Example 1>
Comparative protective film forming agent (D'-1)
In a flask equipped with a stirrer, a thermometer and a condenser tube, 0.72 part of 4,7-diaza-15-crown 5-ether [manufactured by Tokyo Chemical Industry Co., Ltd.], chloromethylstyrene [manufactured by Tokyo Chemical Industry Co., Ltd.] ] 1 part and 10 parts of acetonitrile [manufactured by Wako Pure Chemical Industries, Ltd.] were charged and dissolved uniformly with stirring, and then reacted at room temperature for 24 hours with stirring. Acetonitrile was removed under reduced pressure (1.3 kPa) and then purified by an alumina column [150 mesh, Blockman 1, standard grade, Sigma-Aldrich] using acetone [manufactured by Wako Pure Chemical Industries, Ltd.] as a solvent. 1.1 parts of the compound (C′-1) represented by the formula (yield 75%) was obtained. The compound (C′-1) is used as a comparative electrode protective film forming agent (D′-1).

The electrode protective film forming agents (D-1) to (D-16) and the comparative electrode protective film forming agent (D′-1) of the present invention are summarized in Table 1.

Evaluation of Lithium Secondary Battery and Electrode <Examples 17 to 34, Comparative Examples 2 to 3>
A positive electrode and a negative electrode for a lithium secondary battery containing the electrode protective film forming agent (D) or the comparative electrode protective film forming agent (D ′) in the number of parts shown in Table 2 were prepared by the following method. Using the negative electrode, a lithium secondary battery was produced by the following method.
Table 2 shows the results of evaluating the high-voltage charge / discharge cycle characteristics, output characteristics, and electrode resistance by the following methods.

[Preparation of positive electrode for lithium secondary battery]
90.0 parts of LiCoO ₂ powder, 5.0 parts of Ketjen black [manufactured by Sigma Aldrich], 5.0 parts of polyvinylidene fluoride [manufactured by Sigma Aldrich] and the number of parts of the electrode protective film forming agent shown in Table 2 ( D) or the comparative electrode protective film forming agent (D ′) was thoroughly mixed in a mortar, then 70.0 parts of 1-methyl-2-pyrrolidone was added, and further mixed well in a mortar to obtain a slurry. The obtained slurry was applied to one side of an aluminum electrolytic foil having a thickness of 20 μm using a wire bar in the air, dried at 80 ° C. for 1 hour, and further under reduced pressure (1.3 kPa) at 80 ° C. It was dried for 2 hours and punched out to 15.95 mmφ to produce a positive electrode for a lithium secondary battery.

[Preparation of negative electrode for lithium secondary battery]
92.5 parts of graphite powder having an average particle size of about 8 to 12 μm, 7.5 parts of polyvinylidene fluoride, 200 parts of 1-methyl-2-pyrrolidone, and the number of parts of the electrode protective film forming agent (D) shown in Table 1 or A comparative electrode protective film forming agent (D ′) was sufficiently mixed in a mortar to obtain a slurry. The obtained slurry was applied to one side of a copper foil having a thickness of 20 μm using a wire bar in the atmosphere, dried at 80 ° C. for 1 hour, and further reduced pressure (1.3 kPa) at 80 ° C. for 2 hours. It was dried for a time, punched to 16.15 mmφ, and made a negative electrode for a lithium secondary battery with a thickness of 30 μm using a press.

[Production of lithium secondary battery]
The positive electrode and the negative electrode prepared above were arranged at both ends in the 2032 type coin cell so that the coated surfaces face each other, and a separator (polypropylene nonwoven fabric) was inserted between the electrodes to prepare a secondary battery cell. The solution was poured and sealed in a cell in which an electrolytic solution was prepared by dissolving LiPF ₆ in a mixed solvent of ethylene carbonate (EC) and diethyl carbonate (DEC) (volume ratio 1: 1) at a ratio of 12 wt%.

<Evaluation of high voltage charge / discharge cycle characteristics>
Using a charge / discharge measuring device “Battery Analyzer 1470” [manufactured by Toyo Technica Co., Ltd.], the battery voltage is charged to a voltage of 4.5 V with a current of 0.1 C, and after a pause of 10 minutes, the battery voltage with a current of 0.1 C Was discharged to 3.5 V, and this charge / discharge was repeated. At this time, the battery capacity at the first charge and the battery capacity at the 50th cycle charge were measured, and the charge / discharge cycle characteristics were calculated from the following formula. It shows that charging / discharging cycling characteristics are so favorable that a numerical value is large.
High voltage charge / discharge cycle characteristics (%) = (battery capacity at the 50th cycle charge / battery capacity at the first charge) × 100

<Evaluation of secondary battery output characteristics>
Using a charge / discharge measuring device “Battery Analyzer 1470” [manufactured by Toyo Technica Co., Ltd.], charge to a voltage of 4.5 V with a current of 0.1 C, and after a pause of 10 minutes, apply a voltage with a current of 0.1 C The battery was discharged to 3.0 V, and the discharge capacity (hereinafter referred to as 0.1 C discharge capacity) was measured. Next, the battery was charged to a voltage of 4.5 with a current of 0.1 C, paused for 10 minutes, discharged to a voltage of 3.0 V with a current of 1 C, and the capacity (hereinafter referred to as 1 C discharge capacity) was measured. The capacity maintenance rate at the time of 1C discharge is calculated. The larger the value, the better the output characteristics.
Capacity maintenance rate during 1 C discharge (%) = (1 C discharge capacity / 0.1 C discharge capacity) × 100

<Evaluation of electrode resistance>
Using a charge / discharge measuring device “Battery Analyzer 1470” [manufactured by Toyo Technica Co., Ltd.], the battery voltage is charged to a voltage of 4.5 V with a current of 0.1 C, and after a pause of 10 minutes, the battery voltage with a current of 0.1 C Was discharged to 3.95V. Next, in order to measure the resistance of the electrode, impedance was measured using “SP-150” (frequency range: 200 kHz to 50 mHz, 3.95 V) manufactured by BioLogic, and the resistance was obtained.

Evaluation of Lithium Secondary Battery and Electrolyte <Examples 35 to 50 and Comparative Examples 4 to 5>
A lithium secondary battery using the electrolyte solution for a lithium secondary battery containing the electrode protective film forming agent (D) or the comparative electrode protective film forming agent (D ′) in the blending part shown in Table 2 by the following method. Produced. Similarly to the case of the electrodes, the high voltage charge / discharge cycle characteristics, the output characteristics and the electrode resistance were evaluated by the above-mentioned methods, and the results are shown in Table 2.

[Preparation of electrolyte]
In 87.5 parts of a mixed solvent of ethylene carbonate and diethyl carbonate (volume ratio 1: 1), the electrode protective film forming agent (D) or the comparative electrode protective film forming agent (D ′) is blended in the number of parts shown in Table 1. , there by dissolving LiPF ₆ as an electrolyte (E) so that 12 wt%, thereby preparing an electrolytic solution.

[Production of positive electrode]
After thoroughly mixing 90.0 parts of LiCoO ₂ powder, 5.0 parts of Ketjen black and 5.0 parts of polyvinylidene fluoride in a mortar, 70.0 parts of 1-methyl-2-pyrrolidone was added, and further in a mortar. Mix well to obtain a slurry. The obtained slurry was applied to one side of an aluminum electrolytic foil having a thickness of 20 μm using a wire bar in the air, dried at 80 ° C. for 1 hour, and further under reduced pressure (1.3 kPa) at 80 ° C. It was dried for 2 hours, punched to 15.95 mmφ, and a positive electrode for a lithium secondary battery having a film thickness of 30 μm was produced.

[Production of negative electrode]
A slurry was obtained by thoroughly mixing 92.5 parts of graphite powder having an average particle size of about 8 to 12 μm, 7.5 parts of polyvinylidene fluoride and 200 parts of 1-methyl-2-pyrrolidone in a mortar. The obtained slurry was applied to one side of a copper foil having a thickness of 20 μm using a wire bar in the atmosphere, dried at 80 ° C. for 1 hour, and further reduced pressure (1.3 kPa) at 80 ° C. for 2 hours. After drying for a time, it was punched to 16.15 mmφ, and the thickness was made 30 μm with a press machine to produce a negative electrode for a lithium secondary battery.

[Production of secondary battery]
The positive electrode and the negative electrode were arranged at both ends in the 2032 type coin cell so that the respective coated surfaces face each other, and a separator (polypropylene nonwoven fabric) was inserted between the electrodes to produce a secondary battery cell.
The electrolyte solution was poured into the prepared secondary battery cell and sealed to prepare a secondary battery.

Evaluation of Lithium Ion Capacitor and Electrode <Examples 51 to 68, Comparative Examples 6 to 7>
A positive electrode and a negative electrode for a lithium ion capacitor containing the electrode protective film forming agent (D) or the comparative electrode protective film forming agent (D ′) in the number of parts shown in Table 3 were prepared by the following method. A lithium ion capacitor was prepared by the following method.
As in the case of the lithium secondary battery, the high voltage charge / discharge cycle characteristics and electrode resistance were evaluated by the above method, the output characteristics were evaluated by the following method, and the results are shown in Table 3.

[Production of positive electrode for lithium ion capacitor]
90.0 parts of activated carbon powder, 5.0 parts of Ketjen black, 5.0 parts of polyvinylidene fluoride, and the number of parts of the electrode protective film forming agent (D) or comparative electrode protective film forming agent (D ′) shown in Table 2 After thoroughly mixing with a mortar, 70.0 parts of 1-methyl-2-pyrrolidone was added and further mixed well with a mortar to obtain a slurry. The obtained slurry was applied to one side of an aluminum electrolytic foil having a thickness of 20 μm using a wire bar in the air, dried at 80 ° C. for 1 hour, and further under reduced pressure (1.3 kPa) at 80 ° C. It was dried for 2 hours and punched out to 15.95 mmφ to produce a positive electrode for a lithium ion capacitor.

[Production of negative electrode for lithium ion capacitor]
92.5 parts of graphite powder having an average particle diameter of about 8 to 12 μm, 7.5 parts of polyvinylidene fluoride, 200 parts of 1-methyl-2-pyrrolidone, and the number of parts of the electrode protective film forming agent (D) shown in Table 3 or A comparative electrode protective film forming agent (D ′) was sufficiently mixed in a mortar to obtain a slurry. The obtained slurry was applied to one side of a 20 μm-thick copper foil in the air using a wire bar, dried at 80 ° C. for 1 hour, and further under reduced pressure (1.3 kPa) at 80 ° C. for 2 hours. It was dried, punched to 16.15 mmφ, and made 30 μm thick with a press. The obtained electrode and lithium metal foil are sandwiched between separators (polypropylene nonwoven fabric) and set in a beaker cell, and about 75% of the negative electrode theoretical capacity of lithium ions is occluded in the negative electrode over about 10 hours. A negative electrode was prepared.

[Production of lithium ion capacitors]
The positive and negative electrodes produced above are placed in a storage case made of polypropylene aluminum laminate film so that the coated surfaces face each other, and a separator (polypropylene nonwoven fabric) is inserted between the electrodes to produce a capacitor cell. did. The solution was injected and sealed in a cell in which an electrolytic solution in which LiPF ₆ was dissolved in a proportion of 12% by weight in propylene carbonate (PC) was produced.

<Evaluation of capacitor output characteristics>
Using a charge / discharge measuring device “Battery Analyzer 1470” [manufactured by Toyo Technica Co., Ltd.], the battery is charged to a voltage of 3.8 V with a current of 1 C. After discharging, the discharge capacity (hereinafter referred to as 1C discharge capacity) was measured. Next, the battery is charged to a voltage of 3.8 V with a current of 1 C, and after a pause of 10 minutes, the voltage is discharged to 2.0 V with a current of 10 C, and the capacity (hereinafter referred to as 10 C discharge capacity) is measured. Calculate the capacity maintenance rate at the time. The larger the value, the better the output characteristics.
Capacity maintenance rate during 10C discharge (%) = (10C discharge capacity / 1C discharge capacity) × 100

Evaluation of Lithium Ion Capacitor and Electrolyte <Examples 69 to 84, Comparative Examples 8 to 9>
A lithium ion capacitor using the electrolytic solution for a lithium ion capacitor containing the electrode protective film forming agent (D) or the comparative electrode protective film forming agent (D ′) in the blending number shown in Table 3 was prepared by the following method. . Similarly to the case of the electrodes, the high voltage charge / discharge cycle characteristics, the output characteristics and the electrode resistance were evaluated by the above-mentioned methods, and the results are shown in Table 3.

[Preparation of electrolyte]
In the non-aqueous solvent (F) composed of 87.5 parts of propylene carbonate, the electrode protective film forming agent (D) or the comparative electrode protective film forming agent (D ′) is blended in the number of parts shown in Table 3 and 12 parts are added thereto. of LiPF ₆ as an electrolyte (E) dissolved at a percent by weight, to prepare an electrolytic solution.

[Production of positive electrode]
As the positive electrode active material, activated carbon having a specific surface area of about 2200 m ² / g obtained by an alkali activation method was used. Activated carbon powder, acetylene black, and polyvinylidene fluoride are mixed in a weight ratio of 80:10:10, and this mixture is added to 1-methyl-2-pyrrolidone as a solvent and mixed by stirring. To obtain a slurry. This slurry was applied onto an aluminum foil having a thickness of 30 μm by a doctor blade method, temporarily dried, and then cut so that the electrode size was 20 mm × 30 mm. The electrode thickness was about 50 μm. Before assembling the cell, it was dried in a vacuum at 120 ° C. for 10 hours to produce a positive electrode for a lithium ion capacitor.

[Production of negative electrode]
80 parts of graphite powder having an average particle size of about 8 to 12 μm, 10 parts of acetylene black, and 10 parts of polyvinylidene fluoride are mixed, and this mixture is added to 1-methyl-2-pyrrolidone as a solvent and mixed by stirring. Got. This slurry was applied onto a copper foil having a thickness of 18 μm by a doctor blade method and temporarily dried, and then cut so that the electrode size was 20 mm × 30 mm. The electrode thickness was about 50 μm. Further, it was dried in vacuum at 120 ° C. for 5 hours. The obtained electrode and lithium metal foil are sandwiched between separators (polypropylene nonwoven fabric) and set in a beaker cell, and about 75% of the negative electrode theoretical capacity of lithium ions is occluded in the negative electrode over about 10 hours. A negative electrode was prepared.

[Assembly of capacitor cell]
A separator (nonwoven fabric made of polypropylene) is inserted between the positive electrode and the negative electrode obtained as described above, impregnated with the above electrolyte solution, sealed in a storage case made of polypropylene aluminum laminate film, and lithium ion A capacitor cell was produced.
Similarly to the case of the lithium secondary battery, the high voltage charge / discharge cycle characteristics, the output characteristics, and the electrode resistance were evaluated by the above methods. The results are shown in Table 3.

It has been found that the lithium secondary battery and lithium ion capacitor produced using the electrode protective film forming agent of the present invention are excellent in charge / discharge cycle performance and output characteristics, and can reduce electrode resistance. As a cause of improving the charge / discharge cycle performance and output characteristics, the lithium ion coordination polymer film formed on the surface of the electrode active material suppresses the decomposition of the electrolyte solution on the electrode surface under high voltage, This is considered to reduce the desolvation energy of lithium ions. The cause of the decrease in electrode resistance is thought to be that the salt concentration at the electrode interface increased and the ionic conductivity near the interface increased.

Since the electrode and electrolyte using the electrode protective film-forming agent (D) of the present invention are excellent in charge / discharge cycle performance and output characteristics under a high voltage, the electrode for lithium secondary batteries or lithium ion capacitors is particularly used. In addition, it is useful as an additive for electrolytic solutions, and is suitable for electric vehicles. The present invention can also be applied to other electrochemical devices such as electric double layer capacitors, nickel metal hydride batteries, nickel cadmium batteries, air batteries, alkaline batteries and the like.

Claims

At least one bond (a) selected from the group consisting of urethane bond (a1), urea bond (a2), allophanate bond (a3) and biuret bond (a4), polymerizable unsaturated bond (b) and the following general formula ( The electrode protective film forming agent (D) containing the compound (C) which has group (g) represented by 1).

[M is a monovalent metal ion, and A is —CO 2 − , —SO 3 − , —OPO (OR 1 ) O − , —B (O − ) 2 , —B (OR 2 ) O − or — B (OR 3 ) 3 — (R 1 to R 3 are each a hydrocarbon group having 1 to 10 carbon atoms, and a plurality of R 3 may be the same or different and may form a ring with each other. Good). ]
The electrode protective film forming agent (D) according to claim 1, wherein the compound (C) is represented by the following general formula (2).

[Y is an (s + t) -valent hydrocarbon group having 2 to 42 carbon atoms (Y1), which may contain at least one atom selected from the group consisting of an oxygen atom, a sulfur atom and a nitrogen atom,
A divalent residue obtained by removing two isocyanate groups from a urethane prepolymer having both terminal isocyanate groups, which is a reaction product of a diisocyanate (B) having 4 to 44 carbon atoms and a diol (N) having 2 to 20 carbon atoms ( Y2),
Residue (Y3) obtained by removing (s + t) isocyanate groups from a modified diisocyanate (B) having 9 to 118 carbon atoms having an allophanate bond (a3)
Or a residue (Y4) obtained by removing (s + t) isocyanate groups from a reaction product of a diisocyanate (B) having 11 to 131 carbon atoms having a biuret bond (a4),
s is an integer from 1 to 5, t is an integer from 1 to 5,
(A5) is a urethane bond or a urea bond,
R 7 is a divalent hydrocarbon group having 1 to 12 carbon atoms, R 8 is a monovalent hydrocarbon group having 2 to 30 carbon atoms having a polymerizable unsaturated bond (b), and (g) is the above general formula ( It is group represented by 1). ]
The electrode protective film forming agent (D) according to claim 1 or 2, wherein the concentration of the bond (a) in the compound (C) is 0.2 to 10 mmol / g.
The electrode protective film-forming agent (D) according to any one of claims 1 to 3, wherein the concentration of the polymerizable unsaturated bond (b) in the compound (C) is 0.2 to 10 mmol / g.
The electrode protective film-forming agent (D) according to any one of claims 1 to 4, wherein the number average molecular weight of the compound (C) is 238 to 5000.
The electrode protective film forming agent (D) according to any one of claims 1 to 5, wherein the monovalent metal ion M is a lithium ion or a sodium ion.
The polymerizable unsaturated bond (b) is an alkenyl ether group (j1) represented by the following general formula (3), an alkenyl group (j2) represented by the following general formula (4), and a (meth) acryloyloxy group ( The electrode protective film forming agent (D) according to any one of claims 1 to 6, which is contained in the compound (C) as at least one group (j) selected from the group consisting of j3).

[In the formula (3), T 1 to T 3 are a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. ]

[In Formula (4), T 4 to T 6 are a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and may form a ring with each other. ]
An electrode containing the electrode protective film forming agent (D) according to any one of claims 1 to 7.
The electrode according to claim 8, which has a protective film formed by polymerizing the electrode protective film forming agent (D).
The electrode according to claim 8 or 9, which is for a lithium secondary battery.
The electrode according to claim 8 or 9, which is for a lithium ion capacitor.
An electrolyte solution comprising the electrode protective film forming agent (D) according to any one of claims 1 to 7, an electrolyte (E), and a nonaqueous solvent (F).
The electrolyte solution according to claim 12, which is for a lithium secondary battery.
The electrolyte solution according to claim 12, which is used for a lithium ion capacitor.
A lithium secondary battery comprising the electrode according to claim 10 and / or the electrolytic solution according to claim 13.
A lithium ion capacitor having the electrode according to claim 11 and / or the electrolytic solution according to claim 14.
A method for producing an electrode protective film comprising a step of applying a voltage after the electrode protective film forming agent (D) according to any one of claims 1 to 7 is contained in an electrode and / or an electrolytic solution.