TW201309657A - Additive for electrode, electrode, lithium-ion battery and lithium-ion capacitor - Google Patents

Abstract

An electrode for enhancing high temperature charge and discharge property and high temperature storage property of lithium ion battery or lithium ion capacitor is provided. This invention is an additive for an electrode including: an amino compound (A) containing an amino group and an oxidation potential to a lithium metal of 3.8 to 4.2 V. The amino compound (A) is preferably a triazole (A1) with 1 to 5 amino groups, and more preferably a 1, 2, 4-triazole whose 3-and/or 5-positions are substituted by an amino group.

Description

Electrode additive, electrode, lithium ion battery and lithium ion capacitor

More particularly, the present invention relates to an electrode additive which can be used in a lithium ion battery or a lithium ion capacitor, and an electrode containing the additive for the electrode.

Lithium-ion batteries are characterized by high voltage and high energy density, and are therefore widely used in the field of portable information devices, etc., which need to be rapidly expanded, and are now established as mobile phones and notebook personal computers. The status of the standard battery is the mobile information device. Of course, with the increase in performance and versatility of portable devices and the like, lithium ion batteries as their power sources are required to have higher performance (for example, higher capacity and higher energy density). In order to cope with this demand, various methods have been carried out, such as high density due to an increase in the filling rate of the electrode, improvement in the utilization depth of the existing active material (especially the negative electrode), and development of a novel high-capacity active material. Wait. Moreover, the reality is that lithium ion batteries do increase in capacity due to these methods.

Further, in the lithium ion battery, a nonaqueous electrolytic solution obtained by dissolving a lithium-containing electrolyte such as a lithium salt in an organic solvent is used. In the case where water is mixed into the battery, the lithium-containing electrolyte is decomposed by the reaction with moisture in the nonaqueous electrolytic solution. Therefore, the movement of lithium ions released by the positive electrode active material is hindered, resulting in a decrease in capacity or output power, which further causes a decrease in life. In order to remove moisture in the non-aqueous electrolyte, for example, a technique of mixing an adsorbent in a non-aqueous electrolyte is disclosed (refer to Japanese Patent Laid-Open No. Hei 7-262999) Newspaper).

On the other hand, a technique of adding a base such as benzotriazole to an electrode or an electrolytic solution has been disclosed (refer to Japanese Laid-Open Patent Publication No. 2001-273927).

In the case of using lithium fluoride such as lithium fluoride hexafluoride (LiPF ₆ ) or lithium chloride such as lithium perchlorate (LiClO ₄ ) as the lithium-containing electrolyte, Japanese Patent Publication No. 7-262999 discloses a lithium-ion electrolyte. Even if the amount of water contained in the lithium ion battery is small, decomposition of the lithium-containing electrolyte occurs to produce an acid such as hydrogen fluoride (HF) or perchloric acid (HClO ₄ ). This acid promotes the phenomenon of elution of transition metal ions from the lithium transition metal polyoxide, and as described above, problems such as a decrease in capacity or a decrease in life are caused. In the technique of Japanese Laid-Open Patent Publication No. Hei 7-262999, an adsorbent for removing moisture is mixed, but even if a trace amount of water is decomposed by the lithium-containing electrolyte, it is not sufficient to remove the water by the adsorbent.

Further, Japanese Patent Laid-Open Publication No. 2001-273927 is for the purpose of preventing corrosion of copper used as a negative electrode collector, and adding 1,2,3-benzotriazole or the like capable of capturing HF to an electrode or an electrolyte. Methods. However, since benzotriazole has a low basicity, HF cannot be sufficiently captured, and oxidation stability at a high temperature is low. Therefore, when it is added to an electrolytic solution, decomposition of the positive electrode causes a decrease in cycle characteristics. When it is added to the electrode, it is also slowly dissolved in the electrolytic solution, and the positive electrode is decomposed to cause a decrease in cycle characteristics. Therefore, it is difficult to use it as a driving power source for an automobile or the like which is supposed to be used at a high temperature.

Therefore, an object of the present invention is to provide an electric power which can improve the high temperature charge and discharge cycle performance and high temperature storage characteristics of a lithium ion battery or a lithium ion capacitor. Extreme additive.

The inventors of the present invention conducted intensive studies in order to achieve the above object, and as a result, obtained the present invention. That is, the present invention is an electrode additive containing an amine compound (A) having an amine group and having an oxidation potential of 3.8 V to 4.2 V for metallic lithium; An electrode of an additive; and a lithium ion battery or a lithium ion capacitor using the electrode.

The electrode additive of the present invention (which contains an amine compound (A) having an amine group and having an oxidation potential of 3.8 V to 4.2 V for lithium metal) captures a battery by a neutralization reaction The acid contained in the trace amount of water and the acid such as hydrofluoric acid generated by the reaction of the lithium-containing electrolyte such as LiPF ₆ can suppress the elution of the transition metal ion from the lithium transition metal oxide, and as a result, the charge and discharge cycle performance and the high-temperature storage property are improved. .

By using the electrode containing the additive for an electrode of the present invention, the high-temperature charge and discharge cycle performance and high-temperature storage characteristics of the lithium ion battery or the lithium ion capacitor can be improved.

The lithium ion capacitor is a power storage device having a structure in which a positive electrode of an electric double layer capacitor and a negative electrode of a lithium ion battery are combined, and the electrolytic solution is the same as the lithium ion battery. Therefore, in the lithium ion capacitor, hydrofluoric acid is also generated due to the incorporation of a small amount of moisture, resulting in a decrease in cycle characteristics and high-temperature storage characteristics. Therefore, the additive for an electrode having an amine group of the present invention has the same effect in a lithium ion capacitor.

The electrode additive of the present invention contains an amine compound (A) having an amine group and having an oxidation potential for metal lithium ranging from 3.8 V to 4.2 V.

The amine compound (A) is based on lithium metal, and the oxidation potential by cyclic voltammetry is 3.8 V to 4.2 V. From the viewpoint of charge and discharge cycle characteristics, it is preferably 3.9 V to 4.2 V.

The oxidation potential can be measured by the following method or the like. For example, LiPF ₆ is dissolved in a mixed solvent of ethylene carbonate and diethyl carbonate (volume ratio: 1:1) to prepare an electrolyte of 1 mol/L. A sample for measurement was prepared by dissolving 50 mg of the amine compound (A) of the present invention in 50 g of the electrolytic solution.

After the sample was foamed by argon gas, cyclic voltammetry was carried out using a potential self-regulator HA-301 type manufactured by Hokuto Denko Corporation and a function wave generator HB-104 type. The reference electrode uses a metal lithium foil and the working electrode uses a glass graphite electrode. By scanning the potential from +3.0 V to +5.0 V at a rate of 10 mV per second, the value of the potential at which the oxidation current rises (the potential at which the current is changed by 5% with respect to the peak value of the oxidation current) is taken as Oxidation potential.

The amine compound (A) may have an amine group and an oxidation potential of 3.8 V to 4.2 V with respect to the metal lithium. The amine group may, for example, be a primary amino group or an alkylamino group (methylamino group, dimethylamino group, diethylamino group or dipropylamino group). Preferred among these are primary amine groups.

In the amine compound (A), from the viewpoint of high-temperature charge-discharge cycle characteristics, a triazole (A1) having 1 to 5 amine groups is preferred, and a metal having 1 to 2 amine groups is more preferred. Oxazole.

The triazole (A1) may, for example, be a 1,2,4-triazole derivative [3-amino-1,2,4-triazole, 3,5-diamino-1,2,4-tri Azole, 3,4,5-triamino-1,2,4-triazole, 3-amino-5-methyl-1,2,4-triazole, 3-amino-5-ethyl- 1,2,4-triazole, 3-amino-5-propyl-1,2,4-triazole, 3-amino-5-butyl-1,2,4-triazole, 1-amine Base-1,2,4-triazole, 4-amino-1,2,4-triazole, 3-methyl-4-amino-1,2,4-triazole, 3-ethyl-4 -amino-1,2,4-triazole, 3,5-dimethyl-4-amino-1,2,4-triazole, 3,5-diethyl-4-amino-1, 2,4-triazole, 3,4-diamino-1,2,4-triazole, 4-dimethylamino-1,2,4-triazole and 4-methylamino-1,2 , 4-triazole, etc.]; 1,2,3-triazole derivatives [1-amino-1,2,3-triazole, 2-amino-1,2,3-triazole, 3-amine Base-1,2,3-triazole and 1,2-diamino-1,2,3-triazole, etc.].

Preferred among these compounds are 1,2,4-triazole derivatives, more preferably 1,2,4-triazole substituted at the 3-position and/or 5-position by an amine group.

The 1,2,4-triazole substituted with an amine group at the 3-position and/or the 5-position can be exemplified by 3-amino-1,2,4-triazole and 3,5-diamino-1,2,4- Triazole, 3-amino-5-methyl-1,2,4-triazole, 3-amino-5-ethyl-1,2,4-triazole, 3-amino-5-propyl -1,2,4-triazole and 3-amino-5-butyl-1,2,4-triazole.

Among these compounds, from the viewpoint of high-temperature charge-discharge cycle performance and high-temperature storage characteristics, 3-amino-1,2,4-triazole (oxidation potential is 4.1 V), 3,5-diamine is particularly preferable. Base-1,2,4-triazole (oxidation potential 4.1 V) and 3-amino-5-methyl-1,2,4-triazole (oxidation potential 3.9 V).

The additive for an electrode of the present invention is used by being contained in an electrode, but may be used by a method of directly applying it to the surface of an active material or the like.

The amine compound (A) captures an acid such as HF generated by a reaction between a water contained in a small amount in a battery and a lithium-containing electrolyte such as LiPF ₆ by a neutralization reaction, thereby suppressing elution of a transition metal ion from the lithium transition metal polyoxide. As a result, the charge and discharge cycle performance and the high temperature storage characteristics are improved.

The electrode (positive electrode or negative electrode) of the present invention contains the above-mentioned additive for an electrode, an active material (D), and a binder (E).

The active material (D) includes a negative electrode active material (D1), a positive electrode active material (D2) for a lithium ion battery, and a positive electrode active material (D3) for a lithium ion capacitor.

Examples of the negative electrode active material (D1) include graphite, amorphous carbon, and a polymer compound calcined body (for example, carbonized by baking a phenol resin or a furan resin), and cokes (for example, pitch coke, needle coke, and petroleum coke). ), carbon fibers, conductive polymers (such as polyacetylene and polypyrrole), tin, antimony, and metal alloys (such as lithium-tin alloys, lithium-bismuth alloys, lithium-aluminum alloys, lithium-aluminum-manganese alloys, etc.) .

The positive electrode active material (D2) for a lithium ion battery includes a composite oxide of lithium and a transition metal (for example, LiCoO ₂ , LiNiO ₂ , LiMnO _{2 ,} and LiMn ₂ O ₄ ), and a transition metal oxide (for example, MnO ₂ and V ₂ O _{5 ).} ), transition metal sulfides (such as MoS ₂ and TiS ₂ ), and conductive polymers (such as polyaniline, polyvinylidene fluoride, polypyrrole, polythiophene, polyacetylene, polyparaphenylene, and polycarbazole).

Examples of the positive electrode active material (D3) for a lithium ion capacitor include activated carbon, carbon fibers, and conductive polymers (for example, polyacetylene and polypyrrole).

Examples of the binder (E) include starch, polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, and A polymer compound such as polypropylene.

The electrode of the present invention may further contain an electrode protective film forming agent (F). By including the electrode protective film forming agent (F), a protective film can be formed on the surface of the positive electrode to further improve the stability of the surface of the positive electrode, and the high-temperature charge and discharge cycle characteristics and high-temperature storage characteristics can be further improved.

The electrode protective film forming agent (F) contains a compound represented by the formula (1).

[R ¹ in the formula is a linear or branched aliphatic hydrocarbon group having a carbon number of 1 to 6 or an aliphatic hydrocarbon group having a cyclic structure and having a carbon number of 5 to 12, and a plurality of R ¹ groups may be the same respectively. Alternatively, T ¹ , T ² and T ³ are each independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and n is a number from 1 to 10. ]

The linear or branched aliphatic hydrocarbon group having a carbon number of 1 to 6 in the formula (1) may, for example, be a methylene group, an ethyl group, a propyl group, an ethylene group, a butyl group or a 1-methyl group. Base, 2-methylpropyl, 1-ethylethyl, 1,1-dimethylethyl, ethylmethylmethylene, propylmethylene, pentyl, 1-methyl Butyl butyl, 2-methyl-tert-butyl, 1,1-dimethyl-propyl, 2,2-dimethyl-propyl, 1,2-dimethyl-propyl, 1,3- Methyl propyl, 1-ethylpropyl, 1,1,2-trimethylethyl, 3,3-pentylene, 1-propylethyl, butylmethylene, hexyl, 1-methyl-amyl, 1,1-dimethyl-butyl, 2,2-di Methyl butyl, 1,1,3-trimethylpropyl, 1,1,2-trimethylpropyl, 1,1,2,2-tetramethylethyl, 1,1 - dimethyl-2-ethylethyl, 1,1-diethylethyl, 1-propylpropyl, 2-propylpropyl, 1-butylethyl, 1-methyl-1- Propyl extended ethyl, 1-methyl-2-propylexylethyl, hexylene, 2,2-hexylene and 3,3-heptylene.

The aliphatic hydrocarbon group having a cyclic structure having a carbon number of 5 to 12 in the formula (1) may, for example, be a 1,2-cyclopentyl group, a 1,2-cyclohexylene group, a 1,3-cyclohexylene group, or , 4-cyclohexyl group, residue obtained by removing two hydroxyl groups from 1,3-cyclohexanedimethanol, and residue obtained by removing two hydroxyl groups from 1,4-cyclohexanedimethanol, from 1- The residue obtained by removing two hydroxyl groups from hydroxy-3-hydroxymethylcyclohexane, and the residue obtained by removing two hydroxyl groups from 1-hydroxy-4-hydroxymethylcyclohexane, from 1,4-cyclohexane The residue obtained by removing two hydroxyl groups from the alkyl diethanol and the residue obtained by removing two hydroxyl groups from 1,4-cyclohexane dipropanol are used.

Among these groups, from the viewpoint of cycle characteristics, an aliphatic hydrocarbon group having a cyclic structure of 5 to 12 carbon atoms is preferred, and more preferably two hydroxyl groups are removed from 1,4-cyclohexanedimethanol. And got the residue.

In the general formula (1), T ¹ , T ² and T ³ each independently represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms (methyl group, ethyl group, n-propyl group and isopropyl group).

From the viewpoint of the reactivity of the protective film formation reaction, preferred combinations of T ¹ , T ² and T ³ include the following (1) to (3).

(1) T ¹ = methyl, T ² = hydrogen atom, T ³ = hydrogen atom

(2) T ¹ = hydrogen atom, T ² = methyl group, T ³ = hydrogen atom

(3) T ¹ = hydrogen atom, T ² = hydrogen atom, T ³ = hydrogen atom

More preferred of these combinations is the combination of (2).

In the general formula (1), n is a number from 1 to 10, and from the viewpoint of cycle characteristics, it is preferably from 1 to 4, more preferably from 1 to 2.

Since the compound represented by the formula (1) forms a polymer on the surface of the active material by applying a voltage, the electrode protective film forming agent (F) functions as an electrode protective film forming agent. In other words, by applying an electrode protective film forming agent (F) to the electrode or the electrolytic solution, a voltage is applied to the electrode, and the electrode protective film forming agent (F) is polymerized on the surface of the positive electrode active material to form a protective film. This protective film serves as a protective film for suppressing decomposition of the electrode liquid on the surface of the electrode at a high voltage, and improves charge and discharge cycle characteristics.

When the electrode protective film forming agent (F) is contained in the electrode or electrolyte of the lithium ion battery or the lithium ion capacitor, the protective film is formed at the time of initial charging, and the electrode of the lithium ion battery or the lithium ion capacitor may be used as an electrode. An electrode of a polymeric protective film of the electrode protective film forming agent (F) is formed on the surface of the electrode (the surface of the positive electrode active material).

The electrode protective film forming agent (F) can be synthesized by a usual method, for example, by transesterification of a monool having an alkenyl group and a diol having the above R ¹ and a carbonate in the presence of a basic catalyst. And synthesis.

Examples of the basic catalyst include sodium metal, sodium hydroxide, sodium methoxide, sodium butoxide, potassium metal, potassium hydroxide, potassium methoxide, potassium t-butoxide, and the like.

The monool having an alkenyloxy group may, for example, be ethylene glycol monovinyl ether, ethylene glycol monopropene ether, propylene glycol monovinyl ether, propylene glycol monopropenyl ether or 1-hydroxymethyl-4-(vinyloxymethyl)cyclohexane. Alkane and 1-hydroxymethyl-4-(acryloxymethyl)cyclohexane and the like.

Examples of the diol having the above R ¹ include ethylene glycol, propylene glycol, and 1,4-bis(hydroxymethyl)cyclohexane.

Examples of the carbonate include dimethyl carbonate, diethyl carbonate, and diphenyl carbonate.

The electrode protective film forming agent (F) obtained by the above production method is obtained in the form of a mixture of compounds different from n in the general formula (1), and therefore n in the general formula (1) represents the average thereof. value.

From the viewpoint of the cycle characteristics, the compound represented by the formula (1) is preferably bis[{4-(propenyloxymethyl)cyclohexyl}methyl]carbonate and bis[{4-(vinyl) Oxymethyl)cyclohexyl}methyl]carbonate.

The electrode (positive electrode or negative electrode) of the present invention may further contain a conductive agent (H).

Examples of the conductive agent (H) include graphite (for example, natural graphite and artificial graphite), carbon black (for example, carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, and pyrolytic carbon black) and metal powder (for example). For example, aluminum powder and nickel powder), conductive metal oxides (such as zinc oxide and titanium oxide), and the like.

The preferred content of each of the electrode additive, the active material (D), the binder (E), the electrode protective film forming agent (F), and the conductive agent (H) based on the weight of the electrode in the electrode of the present invention is as follows Said.

The content of the electrode additive is preferably from 0.001 wt% to 1 wt%, more preferably from 0.05 wt% to 0.5 wt%, from the viewpoint of high-temperature charge and discharge cycle characteristics, battery capacity, and high-temperature storage characteristics. 0.1 wt% to 0.3 wt%.

The content of the active material (D) is preferably from 70 wt% to 98 wt%, more preferably from 90 wt% to 98 wt%, from the viewpoint of self-charge and discharge cycle characteristics.

The content of the binder (E) is preferably from 0.5 wt% to 29 wt%, more preferably from 1 wt% to 10 wt%, from the viewpoint of self-charging cycle characteristics.

The content of the electrode protective film forming agent (F) is preferably from 0 wt% to 1 wt%, more preferably from 0.1 wt% to 0.5 wt%, from the viewpoint of self-charging discharge cycle characteristics and high-temperature storage characteristics.

The content of the conductive agent (H) is preferably from 0 wt% to 29 wt%, more preferably from 0 wt% to 10 wt%, from the viewpoint of battery output power.

The electrode of the present invention can be obtained, for example, by using an applicator such as a bar coater, an electrode additive, an active material (D), a binder (E), and optionally an electrode protective film forming agent. (F) and the conductive agent (H) are dispersed in water or a solvent at a concentration of 30 wt% to 60 wt%, and the slurry is applied to a current collector, and dried to remove the solvent, if necessary. The press is pressed.

Here, a positive electrode for a lithium ion battery is obtained by using a positive electrode active material (D2) for a lithium ion battery as an active material (D), and a positive electrode active material (D3) for a lithium ion capacitor is used as an active material (D). A positive electrode for a lithium ion capacitor is obtained. In addition, a negative electrode for a lithium ion battery is obtained by using the negative electrode active material (D1) as an active material (D), and a negative electrode for a lithium ion capacitor is obtained by doping lithium into a negative electrode for a lithium ion battery.

The solvent may, for example, be 1-methyl-2-pyrrolidone, butanone, dimethylformamide, dimethylacetamide, N,N-dimethylaminopropylamine or tetrahydrofuran.

Examples of the current collector include copper, aluminum, titanium, stainless steel, nickel, calcined carbon, a conductive polymer, and conductive glass.

The electrode of the present invention is particularly useful as an electrode for a lithium ion battery or an electrode for a lithium ion capacitor.

The lithium ion battery or the lithium ion capacitor of the present invention can be obtained by combining the electrode of the present invention (either or both of the positive electrode and the negative electrode), and storing it in the tank container together with the separator, and injecting the electrolyte solution. Seal the tank container.

The electrode combined with the electrode of the present invention can be produced by the same method as the electrode of the present invention except that the additive for the electrode is not added.

Examples of the separator include a microporous film made of polyethylene or polypropylene, a multilayer film of a porous polyethylene film and polypropylene, and a nonwoven fabric comprising a polyester fiber, an aromatic polyamide fiber, a glass fiber, and the like. Separators of ceramic fine particles such as cerium oxide, aluminum oxide, and titanium dioxide are attached to the surface.

The electrolyte constituting the lithium ion battery or the lithium ion capacitor of the present invention contains the electrolyte (I) and the nonaqueous solvent (J).

The electrolyte (I) can be used for an electrolyte or the like used in a usual electrolytic solution, and examples thereof include lithium salts of inorganic acids such as LiPF ₆ , LiBF ₄ , LiSbF ₆ , LiAsF ₆ and LiClO ₄ , and LiN(CF ₃ SO ₂ ) _{2 .} Lithium salts of organic acids such as LiN(C ₂ F ₅ SO ₂ ) ₂ and LiC(CF ₃ SO ₂ ) ₃ . Preferred from the viewpoint of battery output power and charge and discharge cycle characteristics, LiPF ₆ is preferred among the compounds.

The nonaqueous solvent (J) can be used for a nonaqueous solvent or the like used in a usual electrolytic solution, and for example, a lactone compound, a cyclic or chain carbonate, a chain carboxylate, a cyclic or chain ether, or the like can be used. Phosphate esters, nitrile compounds, guanamine compounds, hydrazine, cyclobutyl hydrazine, and the like, and mixtures thereof.

Examples of the lactone compound include a 5-membered ring (γ-butyrolactone, γ-valerolactone, etc.) And a 6-membered ring lactone compound (δ-valerolactone, etc.).

Examples of the cyclic carbonate include propylene carbonate, ethylene carbonate, and butylene carbonate.

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.

Examples of the chain carboxylic acid ester include methyl acetate, ethyl acetate, propyl acetate, and methyl propionate.

Examples of the cyclic ether include tetrahydrofuran, tetrahydropyran, 1,3-dioxolane, and 1,4-dioxane.

Examples of the chain ether include dimethoxymethane and 1,2-dimethoxyethane.

Examples of the phosphate ester include trimethyl phosphate, triethyl phosphate, ethyl dimethyl phosphate, diethyl methyl phosphate, tripropyl phosphate, tributyl phosphate, and tris(trifluoromethyl) phosphate. Tris(trichloromethyl)phosphate, tris(trifluoroethyl)phosphate, tris(perfluoroethyl)phosphate, 2-ethoxy-1,3,2-dioxaphosphorane-2- Ketone, 2-trifluoroethoxy-1,3,2-dioxaphosphorane-2-one and 2-methoxyethoxy-1,3,2-dioxaphosphor-2-one Wait.

The nitrile compound may, for example, be acetonitrile or the like. Examples of the guanamine compound include dimethylformamide and the like. Examples of hydrazine include dimethyl hydrazine and diethyl hydrazine.

The nonaqueous solvent (J) may be used alone or in combination of two or more.

From the viewpoint of battery output power and charge and discharge cycle characteristics, a lactone compound, a cyclic carbonate, a chain carbonate, and a phosphate are preferable in the nonaqueous solvent (J), and a lactone compound and a ring are more preferred. A carbonate and a chain carbonate are particularly preferred as a mixture of a cyclic carbonate and a chain carbonate.

The preferred content or concentration of each of the electrolyte (I) and the nonaqueous solvent (J) in the electrolytic solution is as follows.

The concentration of the electrolyte (I) in the electrolytic solution is preferably from 1 wt% to 30 wt%, more preferably from 1 to 3 wt%, based on the weight of the electrolyte, from the viewpoint of battery output power and charge and discharge cycle characteristics. Wt%~15 wt%.

The content of the nonaqueous solvent (J) is preferably 70 wt% to 99 wt%, more preferably 85 wt%, based on the weight of the electrolyte, from the viewpoint of battery output power and charge and discharge cycle characteristics. ~99 wt%.

The electrolyte solution may further contain an electrode protective film forming agent (F). By including the electrode protective film forming agent (F), a protective film can be formed on the surface of the electrode to further improve the stability of the electrode surface, and further improve the charge and discharge cycle characteristics and the high-temperature storage characteristics.

The electrolyte may further contain an additive such as an excessive charge inhibitor, a dehydrating agent, and a capacity stabilizer.

Examples of the overcharge inhibitor include aromatic compounds such as biphenyl, alkylbiphenyl, terphenyl, a tert-triphenyl partial hydrogenator, cyclohexylbenzene, tert-butylbenzene, and tertiary amylbenzene. The amount of use as the overcharge inhibitor is usually from 0 wt% to 5 wt%, preferably from 0 wt% to 3 wt%, based on the total weight of the electrolyte.

Examples of the dehydrating agent include zeolite, silicone, and calcium oxide. The amount of the dehydrating agent to be used is usually 0 wt% to 5 wt%, preferably 0 wt% to 3 wt%, based on the total weight of the electrolyte solution for a lithium ion battery.

Examples of the capacity stabilizer include fluoroethylene carbonate, succinic anhydride, 1-methyl-2-piperidone, heptane, and fluorobenzene. As a capacity stabilizer, the basis It is usually 0 wt% to 5 wt%, preferably 0 wt% to 3 wt%, based on the total weight of the electrolyte.

[Example]

Hereinafter, the present invention will be further illustrated by way of examples, but the invention is not limited to the examples. Hereinafter, parts represent parts by weight.

<Example 1 to Example 16, Comparative Example 1 to Comparative Example 8>

[Production of positive electrode for lithium ion battery]

Based on the formulation shown in Table 1, a positive electrode to which an additive for an electrode, an electrode protective film forming agent, and a comparative compound (Comparative Example) were added was produced by the following method.

90.0 parts of LiCoO ₂ powder, 5 parts of Ketchen Black [Sigma Aldrich], 5 parts of polyvinylidene fluoride [Sigma Aldrich], and the electrode additives and electrode protective film of the parts shown in Table 1 were formed. After sufficiently mixing the compound and the comparative compound in a mortar, 70.0 parts of 1-methyl-2-pyrrolidone [manufactured by Tokyo Chemical Industry Co., Ltd.] was added, and further mixed in a mortar to obtain a slurry. The obtained slurry was applied to one surface of an aluminum electrolytic foil having a thickness of 20 μm in a atmosphere using a ring-type wet film coater, and dried at 100 ° C for 15 minutes, and further under reduced pressure. (2.5 kPa), dried at 80 ° C for 5 minutes, and punched to 15.95 mm φ, and the positive electrodes for lithium ion batteries of Examples 1 to 8 and Comparative Examples 1 to 4 were produced.

[Production of negative electrode for lithium ion battery]

Based on the formulation shown in Table 1, a negative electrode to which an additive for an electrode and a comparative compound (Comparative Example) were added was produced by the following method.

92.5 parts of graphite powder with an average particle size of about 8 μm~12 μm 7.5 parts of difluoroethylene, 1-methyl-2-pyrrolidone [manufactured by Tokyo Chemical Industry Co., Ltd.] 200 parts and the electrode additives and comparative compounds of the parts shown in Table 1 were thoroughly mixed in a mortar. A slurry was obtained. The obtained slurry was applied to one surface of a 20 μm-thick copper foil, dried at 100 ° C for 15 minutes to evaporate the solvent, and then punched to 16.15 mmφ, and the thickness was 30 μm by a press to prepare Example 1 ~Negative electrode for lithium ion battery of Example 8 and Comparative Example 1 to Comparative Example 4.

[Production of positive electrode for lithium ion capacitor]

Based on the formulation shown in Table 2, a positive electrode to which an electrode additive, an electrode protective film forming agent, and a comparative compound (Comparative Example) were added was produced by the following method.

90.0 parts of activated carbon powder, 5.0 parts of Ketchen Black [Sigma Aldrich], 5.0 parts of polyvinylidene fluoride [Sigma Aldrich], and the electrode additives and electrode protection shown in Table 2 After the film-forming agent and the comparative compound were sufficiently mixed in a mortar, 70.0 parts of 1-methyl-2-pyrrolidone [manufactured by Tokyo Chemical Industry Co., Ltd.] was added, and further mixed in a mortar to obtain a slurry. The obtained slurry was applied to one surface of an aluminum electrolytic foil having a thickness of 20 μm in a atmosphere using a ring-type wet film coater, and dried at 100 ° C for 15 minutes, and further under reduced pressure. (2.5 kPa), it was dried at 80 ° C for 5 minutes, and punched to 15.95 mm φ, and the positive electrodes for lithium ion capacitors of Examples 9 to 16 and Comparative Examples 5 to 8 were produced.

[Production of negative electrode for lithium ion capacitor]

Based on the formulation shown in Table 2, the following method was used to make the addition The electrode additive and the negative electrode of the comparative compound (Comparative Example).

92.5 parts of graphite powder having an average particle diameter of about 8 μm to 12 μm, 7.5 parts of polyvinylidene fluoride, 1-methyl-2-pyrrolidone [manufactured by Tokyo Chemical Industry Co., Ltd.], 200 parts, and Table 2 The electrode additive and the comparative compound shown in the number of parts were thoroughly mixed in a mortar to obtain a slurry. The obtained slurry was applied onto one surface of a 20 μm-thick copper foil, and dried at 100 ° C for 15 minutes to evaporate the solvent, and then punched to 16.15 mmφ, and the thickness was 30 μm by a press. The obtained electrode and the lithium metal foil were sandwiched by a separator (polypropylene non-woven fabric) and placed in a cup-shaped groove, and it took about 10 hours to allow the negative electrode to absorb about 75% of the theoretical capacity of the negative electrode. ~Negative electrode for lithium ion capacitor of Example 16 and Comparative Example 5 to Comparative Example 8.

[Evaluation]

Evaluation of lithium ion batteries

(1) Production of lithium ion battery

The positive electrode and the negative electrode of Examples 1 to 8 and Comparative Examples 1 to 4 were placed at both ends of the 2032 type button groove, and the coated surfaces thereof were opposed to each other, and a separator (polypropylene non-woven fabric) was interposed between the electrodes. , making a tank for secondary batteries. An electrolyte solution in which LiPF ₆ is dissolved in a mixed solvent of ethylene carbonate and dimethyl carbonate (volume ratio of 1:1) at a ratio of 1 mol/L is sealed and sealed in the prepared tank by the following The room temperature charge and discharge cycle characteristics, high temperature charge and discharge cycle characteristics, and high temperature storage characteristics were evaluated by the method, and the results are shown in Table 1.

<Evaluation of room temperature charge and discharge cycle characteristics>

Using a charge and discharge measuring device "Battery Analyzer Model 1470" [manufactured by Toyo Technology Co., Ltd.] at room temperature, the battery was charged to a voltage of 4.3 V by a current of 0.1 C, after a pause of 10 minutes, by 0.1 C. The amount of current discharges the battery voltage to 3.0 V, and the charge and discharge are repeated. The battery capacity at the time of initial charging at this time and the battery capacity at the time of charging at the 50th cycle were measured, and the charge and discharge cycle characteristics were calculated according to the following formula. The larger the value, the better the charge-discharge cycle characteristics.

Room temperature charge and discharge cycle characteristics (%) = (battery capacity at the 50th cycle charge / battery capacity at the time of initial charge) × 100

<Evaluation of high temperature charge and discharge cycle characteristics>

The charge and discharge were performed under the same conditions as the above-described evaluation of the room temperature charge and discharge cycle characteristics in an environment of 85 ° C, and the charge and discharge cycle characteristics were calculated according to the following formula. The larger the value, the better the charge-discharge cycle characteristics at high temperatures.

High-temperature charge and discharge cycle characteristics (%) = (battery capacity at the 50th cycle charge / battery capacity at the time of initial charge) × 100

<Evaluation of high temperature storage characteristics>

Using a charge and discharge measuring device "Battery Analyzer Model 1470" [manufactured by Toyo Technology Co., Ltd.], the battery was charged to a voltage of 4.3 V by a current of 0.1 C, and after a pause of 10 minutes, a current of 0.1 C was used. The discharge was performed at a voltage of 3.0 V, and the capacity (first battery capacity) was measured. Further, the battery was charged to a voltage of 4.3 V by a current of 0.1 C, and stored at 85 ° C for 7 days, and then discharged to 3.0 V by a current of 0.1 C to measure the battery capacity (battery capacity after high-temperature storage). The high temperature storage characteristics were calculated according to the following formula. The larger the value, the better the high temperature storage characteristics.

High temperature storage characteristics (%) = (battery capacity after high temperature storage / primary battery capacity) × 100

Evaluation of lithium ion capacitors

(2) Production of lithium ion capacitors

The positive electrode and the negative electrode of Example 9 to Example 16 and Comparative Example 5 to Comparative Example 8 were placed in a storage case containing an aluminum composite film of polypropylene, and the respective coated faces were opposed to each other, and a separator was interposed between the electrodes (polypropylene) Non-woven fabric), making a slot for capacitors. An electrolyte solution in which LiPF ₆ is dissolved in a mixed solvent of ethylene carbonate and dimethyl carbonate (volume ratio 1:1) at a ratio of 1 mol/L is sealed in the prepared tank by the following The method was evaluated for high voltage charge and discharge cycle characteristics and high temperature storage characteristics, and the results are shown in Table 2.

<Evaluation of room temperature charge and discharge cycle characteristics>

Using a charge and discharge measuring device "Battery Analyzer Model 1470" [manufactured by Toyo Technology Co., Ltd.] at room temperature, the battery was charged to a voltage of 4.0 V by a current of 1.0 C, after a pause of 10 minutes, by 1.0. The amount of current of C was discharged to a voltage of 2.0 V, and the charge and discharge were repeated. The capacity of the capacitor at the time of initial charging at this time and the capacity of the capacitor at the time of charging at the 50th cycle were measured, and the charge and discharge cycle characteristics were calculated according to the following formula. The larger the value, the better the charge-discharge cycle characteristics.

Room temperature charge and discharge cycle characteristics (%) = (capacitor capacity at the 50th cycle charge / capacitor capacity at the time of initial charge) × 100

<Evaluation of high temperature charge and discharge cycle characteristics>

The charge and discharge were performed under the same conditions as the above-described evaluation of the room temperature charge and discharge cycle characteristics in an environment of 85 ° C, and the charge and discharge cycle characteristics were calculated according to the following formula. The larger the value, the better the charge-discharge cycle characteristics at high temperatures.

High-temperature charge and discharge cycle characteristics (%) = (capacitor capacity at the 50th cycle charge / capacitor capacity at the time of initial charge) × 100

<Evaluation of high temperature storage characteristics>

Using a charge and discharge measuring device "Battery Analyzer Model 1470" [manufactured by Toyo Technology Co., Ltd.], the battery was charged to a voltage of 4.0 V by a current of 1.0 C, and after a pause of 10 minutes, a current amount of 1.0 C was used. The discharge was performed at a voltage of 2.0 V, and the capacity (primary capacitor capacity) was measured. Further, the battery was charged to a voltage of 4.0 V by a current of 1.0 C, and stored at 85 ° C for 7 days, and then discharged to 2.0 V by a current of 1.0 C to measure the capacitor capacity (capacitor capacity after high-temperature storage). The high temperature storage characteristics were calculated according to the following formula. The larger the value, the better the high temperature storage characteristics.

High temperature storage characteristics (%) = (capacitor capacity after high temperature storage / primary capacitor capacity) × 100

[Industrial availability]

Since the electrode using the electrode additive (A) of the present invention is excellent in cycle characteristics at high temperatures and high-temperature storage stability, it can be used particularly as an electrode for a lithium ion battery or an electrode for a lithium ion capacitor, and is suitable for use in an electric vehicle. .

Claims (10)

An additive for an electrode comprising an amine compound (A) having an amine group and having an oxidation potential for metal lithium ranging from 3.8 V to 4.2 V. The additive for an electrode according to claim 1, wherein the amine compound (A) is a triazole (A1) having one to five amine groups. The additive for an electrode according to the second aspect of the invention, wherein the triazole (A1) is a 1,2,4-triazole substituted with an amine group at the 3-position and/or the 5-position. The electrode additive according to claim 2, wherein the triazole (A1) is selected from the group consisting of 3-amino-1,2,4-triazole and 3,5-diamine. Base-1,2,4-triazole, 3-amino-5-methyl-1,2,4-triazole, 3-amino-5-ethyl-1,2,4-triazole, 3 At least one of the group consisting of amino-5-propyl-1,2,4-triazole and 3-amino-5-butyl-1,2,4-triazole. An electrode comprising an additive for an electrode according to any one of claims 1 to 4. The electrode according to claim 5, which contains an additive for an electrode of 0.001 wt% to 1 wt% based on the weight of the electrode. The electrode according to claim 5, wherein the electrode further comprises an electrode protective film forming agent (F) containing a compound represented by the formula (1); 1] [wherein R ¹ is a linear or branched aliphatic hydrocarbon group having a carbon number of 1 to 6 or an aliphatic hydrocarbon group having a cyclic structure and having a carbon number of 5 to 12, and a plurality of R ¹ may be the same or different Differently, T ¹ , T ² and T ³ are each independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and n is a number from 1 to 10. An electrode comprising a protective film formed of the electrode protective film forming agent (F) according to claim 7 of the patent application. A lithium ion battery having the electrode according to any one of claims 5 to 8. A lithium ion capacitor having the electrode according to any one of claims 5 to 8.