JP2010146726A - Conductive composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a conductive composition which makes it possible to incorporate a space-saving safeguard device in order to shut down electric current safely without any complicated processes when abnormal heat generation of an electronic device occurs, as well as a conductive composition for a battery collector coat to improve charge and discharge characteristics of the battery. <P>SOLUTION: The conductive composition including a foaming material foamed by heat and a conductive material is characterized as realizing conductivity below a predetermined temperature and realizing insulation at or above a predetermined temperature by way of foaming of the foaming material. Moreover, it is characterized by containing materials with a hydrogen bonding functional group value of 1.0-5.0×10<SP>-2</SP>mol/g and a conductive material, and being the conductive composition for the battery collector coat which is enabled to form a cake as well as to be fluid, and containing not less than 50 wt.% of substances with a hydrogen bonding functional group value of 1.0-5.0×10<SP>-2</SP>mol/g in a solid except for the conductive materials after cake-forming. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention is a conductive composition containing a foamable substance and a conductive material that foams by heat, and the conductive composition becomes an insulator by foaming the foamable substance at a predetermined temperature or higher. A battery current collector coat comprising a substance having a specific amount of hydrogen-bonding functional group value of 1.0 to 5.0 × 10 ⁻² mol / g and a conductive material, and capable of solidifying and being fluid. The present invention relates to a conductive composition for electronic use and an electronic device including the conductive composition.

  As a member that becomes an insulator when the temperature exceeds a predetermined arbitrary temperature, there is a method of using a metal that melts when the temperature exceeds a predetermined temperature. For example, it is widely used as a fuse and is incorporated as a safety device in many electronic devices. In this case, even if a current exceeding the rating flows to the electronic device through the fuse, the fuse is heated by the Joule heat of the current to reach a temperature at which the metal constituting the fuse melts, and the metal wiring melts down and becomes excessive. The current is cut off and the electronic device is protected from electrical damage. In addition, such a safety device can prevent a fire due to abnormal heat generation of the circuit.

  There is also disclosed a fuse in which a metal to be melted is hollow and a thermally expansible gas is sealed inside, and the electric conduction is reliably cut off together with the effect of mechanical breakage due to gas expansion (Patent Document 1). ). Further, a varistor (nonlinear resistance element) whose resistance value increases as the voltage increases is also used for the purpose of preventing electrical damage to the circuit (Patent Document 2), and a varistor with a built-in fuse is also disclosed ( Patent Document 3).

  On the other hand, a method for improving the adhesion between the active material layer and the current collector by coating the surface of the battery current collector with a conductive composition is also disclosed (Patent Documents 4, 5, and 6).

JP 2000-215729 A JP-A-5-6805 JP-A-5-6804 Japanese Patent Laid-Open No. Sho 63-121265 JP-A-7-201362 JP-A-7-201362

  In order to install a conventional safety device using a heat sensor such as a fuse or a varistor in an electronic device, a space for installing the safety device and the safety device and a process for installing the safety device are separately required. In addition, when the installation space of the thermal sensor is limited, such as a thin small device, or when abnormal heat generation parts suddenly occur over a wide range of battery components, such as a battery, the conventional safety device cannot cover it. It was.

  In addition, by coating the surface of the battery current collector with a conventional conductive composition, the adhesion between the active material layer and the current collector layer could be improved, but the atoms constituting the active material during charging and discharging The mutual substitution reaction with the atoms constituting the current collector cannot be effectively suppressed, and the atomic mutual substitution generated between the active material layer and the conductive coating layer and / or the conductive coating layer and the current collector is not possible. The generation of the accompanying voids and the increase in the battery internal resistance due to the generation of the voids could not be suppressed.

  As a result of diligent research to solve the above-mentioned problems, the present inventors have developed a conductive composition containing a foamable substance and a conductive material that are foamed by heat, and further solidify the conductive composition. Developed a type with possible fluidity, and by solidifying it in the circuit of the electronic device, etc., it can be incorporated into any part of the electronic device easily and in a space-saving manner. It has been found that the conductive material is foamed, and the current can be safely interrupted by breaking the conductive material and making the conductive composition insulative, and the present invention has been completed.

  The present invention is a conductive composition comprising a foamable substance and a conductive material that foams by heat, and imparts conductivity below a predetermined temperature, but the foamable substance foams above the predetermined temperature. It is related with the electroconductive composition characterized by becoming insulating by this.

  The present invention also relates to a conductive composition having fluidity that can be solidified, comprising a foamable substance that is foamed by heat and a conductive material. The composition is electrically conductive at a temperature lower than a predetermined temperature after solidification. The present invention relates to a conductive composition characterized in that the foamable material becomes insulative when foamed at a temperature of 5 ° C. or higher.

Furthermore, as a result of intensive studies to solve the above-mentioned problems, the present inventors include a substance having a hydrogen bondable functional group value of 1.0 to 5.0 × 10 ⁻² mol / g and a conductive material, A conductive composition for battery current collector coating that can be solidified and has fluidity, and has a hydrogen-bonding functional group value of 1.0 to 5.0 × 10 ^-2 mol in a solid excluding the conductive material after solidification By using a current collector coated with a conductive composition for coating a current collector of a battery, characterized in that it contains 50 wt% or more of a substance that is / g, a current collector and an element constituting the active material are formed. The inventors have found that mutual substitution reaction (mutual migration) of elements can be suppressed, and have completed the present invention. Moreover, it came to complete the collector coating electroconductive composition which becomes an insulator above arbitrary temperature by adding the said foaming agent to the said electroconductive composition for collector coating.

  The present invention also relates to an electric circuit made of the conductive composition, an electronic device including the electric circuit, an electrode coated with the conductive composition, and a disassembly member assembled with the conductive progeny.

According to the conductive composition and the conductive composition for current collector coating of the present invention, a safety mechanism can be easily incorporated into an electronic device at a low cost. In addition, it is a conductive composition for a battery current collector coat that includes a substance having a hydrogen bondable functional group value of 1.0 to 5.0 × 10 ⁻² mol / g and a conductive material, and can be solidified and has fluidity. A battery current collector comprising a solid having a hydrogen bonding functional group value of 1.0 to 5.0 × 10 ⁻² mol / g in an amount of 50% by weight or more in a solid excluding the conductive material after solidification By using the coating conductive composition, a battery having low battery internal resistance and excellent charge / discharge characteristics can be produced.

  In addition, according to the conductive composition having fluidity that can be solidified and formed according to the present invention, it can be solidified and formed into an arbitrary shape. A safety mechanism can be easily incorporated into an electronic device at a low cost without requiring much space for installation.

  In addition, according to the conductive composition of the present invention, it is possible to use a conductive composition having fluidity that can be solidified, so that the formation of a conductive member and the installation of a safety mechanism can be performed at the same time. By using the conductive composition for assembling and electrode coating, it is possible to reduce the step of separately incorporating a conventional safety device.

In addition, it is a conductive composition for a battery current collector coat that includes a substance having a hydrogen bondable functional group value of 1.0 to 5.0 × 10 ⁻² mol / g and a conductive material, and can be solidified and has fluidity. A battery current collector comprising a solid having a hydrogen bonding functional group value of 1.0 to 5.0 × 10 ⁻² mol / g in an amount of 50% by weight or more in a solid excluding the conductive material after solidification By using the current collector coated with the conductive composition for coating, the mutual substitution reaction between the element constituting the active material and the element constituting the current collector at the time of charge / discharge can be suppressed. Controlling the generation of voids due to atomic mutual substitution (mutual migration) occurring between the layer and the conductive coating layer and / or the conductive coating layer and the current collector, and the increase in battery internal resistance due to the generation of the voids Can do.

  The conductive composition of the present invention is a conductive composition including a foamable substance and a conductive material that foams by heat, and imparts conductivity at a temperature lower than a predetermined temperature, but the foaming occurs at a temperature equal to or higher than the predetermined temperature. The insulating material is characterized by foaming the insulating material.

  In addition, the flowable conductive composition of the present invention is a flowable conductive composition that includes a foamable substance and a conductive material that foams by heat, and is at least solidified. It is characterized in that it is conductive at a temperature lower than a predetermined temperature after formation, but becomes insulative when the foamable material is foamed above the predetermined temperature.

The present invention includes a substance having a hydrogen bondable functional group value of 1.0 to 5.0 × 10 ⁻² mol / g and a conductive material, and is a solidified and flowable conductive composition for a battery current collector coating. A solid battery excluding the conductive material after solidification contains 50% by weight or more of a substance having a hydrogen bond functional group value of 1.0 to 5.0 × 10 ⁻² mol / g. It is the electroconductive composition for electrical conductor coating, The charging / discharging characteristic of a battery can be improved by coating a collector with this, It is characterized by the above-mentioned.

In addition, it is a conductive composition for a battery current collector coat that includes a substance having a hydrogen bondable functional group value of 1.0 to 5.0 × 10 ⁻² mol / g and a conductive material, and can be solidified and has fluidity. A battery current collector comprising a solid having a hydrogen bonding functional group value of 1.0 to 5.0 × 10 ⁻² mol / g in an amount of 50% by weight or more in a solid excluding the conductive material after solidification The coating conductive composition can be blended with various solvents and foaming agents, and is characterized in that it improves the charge / discharge characteristics of the battery and prevents thermal runaway when an abnormal current flows by foaming.

  A foamable substance that foams by heat is a substance that expands by volume when heated to a predetermined temperature or higher after the conductive composition is solidified, and expands by volume more than other components such as the conductive composition. A substance having a large volume can be used, and a substance that rapidly undergoes volume expansion when a predetermined temperature is reached is preferable. Examples of the material having a large volume expansion include a material that undergoes thermal decomposition when it reaches a predetermined temperature, a material that sublimes, a material that boils, and the like.

  An electroconductive material is a material which provides electroconductivity to an electroconductive composition and the electroconductive composition for collector coating, and arbitrary electroconductive materials can be used combining it suitably. As the conductive material having fluidity that can be solidified, a molten metal, an alloy, or the like can be used. A molten conductive polymer can also be used. Moreover, these electroconductive materials can also be used by making it a fluid powder, and can be solidified by baking or compressing. As described below, when the conductive material further includes an insulating material having fluidity that can be solidified, the conductive material may not have solidification ability or fluidity. Also, a foamable conductive composition is formed along the shape of the fluidized foamable material solidified by impregnating the fluidized foamable material with solidified fluidity into a solidified fluidized material. It is also possible to do.

  The conductive composition refers to a composition containing at least a conductive substance. The conductive composition having fluidity can be solidified and at least conductive after solidification. Here, the term “conductive” refers to a state in which the conductive composition after solidification substantially flows current, and a conductive composition having an arbitrary resistance value can be used according to the application. To impart conductivity means that at least the conductive composition after solidification has conductivity.

  Insulation refers to a state in which no current flows substantially, and refers to a state in which the electrical resistance value is higher than at least the conductive composition before foaming.

  The fluidity means that the conductive composition moves into an arbitrary shape, and preferably has a viscosity suitable for various forming methods and printing methods, and has a viscosity enough to maintain the shape after forming. Can be selected in a timely manner.

  Solidification means that a conductive composition having fluidity is fixed in an arbitrary shape and is not fluid in the environment of use.

  Here, the predetermined temperature is a temperature at which the solidified conductive composition becomes insulative, and the conductive composition becomes an insulator above the predetermined temperature. Moreover, it can be controlled to become an insulator at a desired temperature by changing the temperature at which the foamable substance contained in the conductive composition foams. In addition, the conductive composition that has been foamed and changed to an insulator when the temperature reaches a predetermined temperature can continuously block the flow of electricity by maintaining the insulating state even when the temperature is lower than the predetermined temperature.

  The conductive composition can further include an insulating material. As the insulating material, a material that can impart solidification forming ability, fluidity, adhesiveness, flexibility, water resistance and the like to the conductive composition can also be used.

  The foamable substance generally has a large volume expansion coefficient when it becomes a gas from a solid or liquid, and is preferably a solid or liquid that vaporizes at the predetermined temperature. The vaporization includes chemical decomposition, sublimation, You can choose what is done by boiling. By selecting a foaming substance having a large expansion ratio, the efficiency of making an insulator can be increased, and a substance having a volume expansion coefficient of 10 times or more is preferable, and a substance having a volume expansion coefficient of 50 times or more is more preferable. .

  When the foamable substance that undergoes chemical decomposition when it reaches a predetermined temperature is composed of, for example, one molecule, it is chemically decomposed into two or more molecules, so the volume expansion coefficient is further increased, and the foaming ratio of the foaming agent is increased. The efficiency of making an insulator can be increased. Substances causing such chemical decomposition include sodium hydrogen carbonate, p, p'-oxybisbenzenesulfonyl hydrazide, azodicarbonamide, N, N'-dinitrosopentamethylenetetramine, 4,4'-oxybis (benzene). Sulfonyl hydrazide) and the like.

  Examples of the foamable substance that sublimes when it reaches a predetermined temperature include naphthalene, 1,7,7-trimethylbicyclo [2.2.1] heptan-2-one, dry ice, iodine and the like.

  Foamable substances that boil when a certain temperature is reached include hydrocarbons (propane, n-butane, n-pentane, isohexane, cyclohexane, n-octane, isooctane, benzene, toluene, xylene, ethylbenzene, amylbenzene, turpentine oil, Pinene, etc.), halogenated hydrocarbons (methyl chloride, chloroform, carbon tetrachloride, ethylene chloride, methyl bromide, ethyl bromide, chlorobenzene, chlorobromomethane, bromobenzene, fluorodichloromethane, dichlorodifluoromethane, difluorochloroethane, etc.), Alcohol (methanol, ethanol, n-propanol, isopropanol, n-amyl alcohol, isoamyl alcohol, n-hexanol, n-heptanol, 2-octanol, n-dodecanol, nonanol, Lohexanol, glycidol, etc.), ether, acetal (ethyl ether, dichloroethyl ether, isopropyl ether, n-butyl ether, diisoamyl ether, methylphenyl ether, ethylbenzyl ether, furan, furfural, 2-methylfuran, cineol, methylal) , Ketones (acetone, methyl ethyl ketone, methyl n-propyl ketone, methyl n-amyl ketone, diisobutyl ketone, phorone, isophorone, cyclohexanone, acetophenone, etc.), esters (methyl formate, ethyl formate, propyl formate, methyl acetate, ethyl acetate, Propyl acetate, n-amyl acetate, methyl cyclohexyl acetate, methyl butyrate, ethyl butyrate, propyl butyrate, butyl stearate, etc.), polyhydric alcohols and their derivatives ( Tylene glycol, ethylene glycol monomethyl ether, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether, methoxymethoxyethanol, ethylene glycol monoacetate, diethylene glycol, diethylene glycol monomethyl ether, propylene glycol, propylene glycol monoethyl ether, etc.), fatty acids and phenols ( Formic acid, acetic acid, acetic anhydride, propionic acid, propionic anhydride, butyric acid, isovaleric acid, phenol, cresol, o-cresol, xylenol, etc., nitrogen compounds (nitromethane, nitroethane, 1-nitropropane, nitrobenzene, monomethylamine, dimethyl) Amine, trimethylamine, monoethylamine, diamylamine, aniline, monomethyl Aniline, o-toluidine, o-chloroaniline, dichloroamine, dicyclohexylamine, monoethanolamine, formamide, N, N-dimethylformamide, acetamide, acetonitrile, pyridine, α-picoline, 2,4-lutidine, quinoline, morpholine Etc.), sulfur, phosphorus, other compounds (carbon disulfide, dimethyl sulfoxide, 4,4-diethyl-1,2-dithiolane, dimethyl sulfide, dimethyl disulfide, methanethiol, propane sultone, triethyl phosphate, tophenyl phosphate, carbonic acid Examples thereof include liquids such as diethyl, ethylene carbonate, amyl borate), inorganic solvents (liquid ammonia, silicone oil, etc.), liquid metals, and water.

  The gas generated from the foamable material is preferably flame retardant, and can prevent or minimize damage even when a fire occurs due to abnormal heat generation of the electronic device.

  The foamable material can be coated with a softening material that softens above the predetermined temperature. It is preferable that this softening substance film does not rupture as a result of foaming of the foaming substance, and the gas generated inside is confined to expand, and the foaming of the conductive material is achieved by expanding the softening substance like a balloon by foaming. Efficiency can be increased. In addition, when the temperature of the conductive composition decreases or abnormal stress is applied to the conductive composition, the conductive material comes into contact with the conductive composition to restore conductivity. Can be prevented by the swollen softening substance.

  The temperature at which the softening material softens is preferably closer to the foaming temperature, and more preferably higher than the foaming temperature. The temperature difference between the softening temperature and the foaming temperature is preferably within 100 ° C. Examples of such softening substances include various thermoplastic polymers that are organic substances, and examples thereof include polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyvinyl alcohol, polyvinyl acetate, and acrylonitrile butadiene styrene resin. .

  These foamable substances can be used alone or in appropriate combination of two or more as required.

  As the conductive material, a metal or an alloy can be used. In the case of an alloy, a low melting point alloy can be preferably used. When the conductive material is a metal or an alloy, electrical connection can be made with low resistance. Examples of such an alloy include Sn—Pb, Sn—In, Sn—Bi, Sn—Ag, and Sn—Zn alloys.

  As the conductive material, when the conductive composition and the conductive composition for current collector coating include a fluid insulating material that can be solidified, a conductive filler can be used. Examples of such conductive filler include Ag, Cu, Au, Al, Mg, Rh, W, Mo, Co, Ni, Pt, Pd, Cr, Ta, Pb, V, Zr, Ti, In, Fe, and Zn. Metal powder, flakes or colloids such as Sn—Pb, Sn—In, Sn—Bi, Sn—Ag, Sn—Zn alloy powders and flakes, acetylene black, furnace black Carbon black such as channel black, graphite, graphite fiber, graphite fibril, carbon fiber, activated carbon, charcoal, carbon nanotube, fullerene and other conductive carbon materials, metal oxide conductive fillers include zinc oxide and tin oxide , Indium oxide, titanium oxide (titanium dioxide, titanium monoxide, etc.) Ri surplus electrons filler, and the like indicating the generated conductive. Such fillers can be used alone or in combination of two or more, and it is also preferable to use a filler whose surface is treated with a coupling agent or the like.

  The conductive filler is preferably conductive particles, and the size of the particles is more preferably smaller than the size of the member to be formed. When the conductive particles are blended in a fluid conductive composition capable of solidifying, the conductive particles can be imparted by contacting each other in the fluid conductive composition capable of solidifying. As such conductive particles, powders or flakes of the above metals or alloys can be used.

  The conductive particles preferably have a flat shape that can be oriented by an electric field, a magnetic field, or both. In this case, the conductive composition can be solidified in a state where the conductive particles are oriented. The solidified product of the conductive composition has anisotropy in the electric resistance value corresponding to the direction oriented by the electric field or the magnetic field or both, and the orientation is obtained by foaming the foamable material in this state. The conductive composition can be changed into an insulator more efficiently than the disturbance. Orienting the conductive particles to form a member having a low electrical resistance value is a preferred embodiment from the viewpoint of increasing the electrical efficiency of the electronic device. Further, when the foamable substance is a flat particle and has magnetic anisotropy or dielectric anisotropy, it can be oriented by an electric field, a magnetic field, or both.

  As the conductive substance having fluidity, an ionic liquid can be exemplified. Examples of ionic liquids include liquids in which ions are dissolved. Examples of the solvent include water such as sodium chloride, potassium chloride, and lithium chloride. If the solvent is an organic substance such as dimethyl carbonate, hexafluoride. Examples thereof include lithium phosphate. As another example of the ionic liquid, an ionic liquid can be exemplified. Examples of ionic liquids include 1,3-dimethylimidazolium methyl sulfate, 1-ethyl-3-methylimidazolium bis (pentafluoroethylsulfonyl) imide, 1-ethyl-3-methylimidazole as imidazolium salt derivatives. Palladium bromide, pyridinium salt derivatives, 3-methyl-1-propylpyridium bis (trifluoromethylsulfonyl) imide, 1-butyl-3-methylpyridinium bis (trifluoromethylsulfonyl) imide, alkylammonium derivatives, tetra Examples of butylammonium heptadecafluorooctane sulfonate, tetraphenylammonium methanesulfonate, and phosphonium salt derivatives include tetrabutylphosphonium methanesulfonate. .

  A foamable conductive composition can also be formed by impregnating a porous material containing a foamable material formed into an arbitrary shape with these ionic liquids. Examples of such a porous material include paper and nonwoven fabric containing a foamable material, a porous polymer material, and the like.

  These conductive materials can be used alone or in combination of two or more as required.

  The conductive composition may be a composite in which the foamable substance and at least a part of the conductive material are integrated. By integrating at least a part of the insulating foamable substance and the conductive material, the conductive foamable substance can be manufactured.

  Furthermore, the composite is particularly preferably a foamable material whose surface is coated with a conductive material. When an insulative material is mixed with a foamable material or a foamable material coated with the softening material, the electrical resistance increases and the electrical efficiency of the electronic device decreases. However, an increase in electrical resistance can be suppressed by coating the surface of the composite with a conductive substance. Specifically, it can be obtained by plating the surface of a foamable substance or a foamable substance coated with softening or attaching conductive particles. As the conductive substance, the above-described metals, alloys, carbon-based materials, and various inorganic substances having conductivity can be used. When the conductive substance is a metal, a dense metal layer is formed on the surface of the foamable substance by plating. be able to. Thus, by providing conductivity, the content of the foamable substance can be increased, and the range of selection of the foaming ratio of the conductive composition can be expanded.

  Furthermore, the surface of the foamable substance is densely coated with a conductive material, whereby the gas generated from the foamable substance can be contained, and the foaming characteristics of the foamable substance can be maintained over a long period of time. Furthermore, by gradually preventing foaming, it is possible to prevent the resistance value of the conductive composition from gradually increasing during a steady state. The prescription as described above is effective for applications that require maintenance of electrical characteristics and foaming characteristics over a long period of time (such as home appliances and in-vehicle electronic devices). Note that the conductive material covered with foaming of the foamable material breaks, but when the foamable material is covered with a softening material, the softening material foams due to leakage of gas generated from the foamable material. It is possible to prevent the efficiency from being lowered and maintain the foaming efficiency of the conductive composition.

  The insulating material is preferably a liquid, but particles and gases are also applicable, and any material can be used as long as it can solidify after forming a fluidity-imparting composition in any shape. be able to. When it is a liquid, it can be simply printed or formed into an arbitrary shape by various devices such as dispensing, screen printing, and ink jet.

  As the fluid insulating material, a curable organic component and an inorganic component can be appropriately used. Among these, as an organic component, in addition to various epoxy compounds, siloxane compounds, etc., prepolymers such as curable monomers and oligomers can be used, and these can be melted in a polymer state or dissolved in a solvent. It can also be used, or a fine powder having fluidity can be used. Among these, thermoplastic resins include vinyl acetate, vinyl alcohol, vinyl butyral, vinyl chloride, methacrylate, acrylic acid, methacrylic acid, styrene, ethylene, amide, cellulose, isobutylene, vinyl ether, polyvinylidene fluoride, polyester, and the like. A prepolymer and a polymer can be mentioned. Examples of the thermosetting resin include urea, melamine, phenol, resorcinol, epoxy, oxetane, episulfide, isocyanate, a mixture of chitosan and carboxylic acid, a prepolymer and a polymer made of imide and the like. These compounds can be used alone or in combination of two or more.

Among the curable organic component and inorganic component, the curable component having a hydrogen bond functional group value of 1.0 to 5.0 × 10 ⁻² mol / g is the conductive composition for battery current collector coating of the present invention. Can be used for This conductive composition for battery current collector coating is solidified and fluid, and has a hydrogen bonding functional group value of 1.0 to 5.0 × 10 ^-2 mol in the solid material excluding the conductive material after solidification. It is characterized by containing a substance which is / g at 50% by weight or more. By using the current collector coated with the conductive composition for battery current collector coating, mutual substitution reaction between the element constituting the active material and the element constituting the current collector can be suppressed. The conductive composition for battery current collector coating is obtained by adding a material having a hydrogen bonding functional group value of 1.0 to 5.0 × 10 ⁻² mol / g to a solid material excluding the conductive material after solidification. It is contained at 70% by weight or more, more preferably 90% by weight or more.

The hydrogen bonding functional group refers to a functional group capable of causing hydrogen bonding, and includes a functional group (1) having a structural unit in which a hydrogen atom is bonded to an oxygen atom or a structural unit in which a hydrogen atom is bonded to a nitrogen atom. Examples of the functional group (2) are:


(R1 and R2 each independently represents an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, a group having an aromatic ring having 7 to 18 carbon atoms, or a derivative thereof)

Specifically, a hydroxy group (—OH), a carboxyl group (—COOH), an amino group (—NH ₂ , —NHR 1), a hydrazide group (R 1 R ₂ NN (R 3) C (═O) R 4), a hydroxylamino group (— NHOH), etc. can be exemplified, but not limited thereto. R3 and R4 are synonymous with R1 or R2.

  A substance having such a functional group can increase the cross-linking density by hydrogen bonding between molecules. Therefore, when used as a coating agent for a battery current collector, an element and an active material constituting the current collector are used. Mutual substitution reaction of constituent elements can be suppressed.

The hydrogen bondable functional group value is obtained by dividing the number of functional groups exhibiting hydrogen bondability in a molecule by the molecular weight.
[Formula 1]
(Formula 1) Hydrogen bondable functional group value (mol / g) = number of hydrogen bondable functional groups in one molecule / molecular weight

The hydrogen bonding functional group values of typical substances are shown below.
Polyvinyl alcohol Polyvinyl alcohol (average polymerization degree 500, saponification degree 100%) = 2.3 × 10 ⁻² mol / g
Polyvinyl alcohol (average polymerization degree 1000, saponification degree 100%) = 2.3 × 10 ⁻² mol / g
Polyvinyl alcohol (average polymerization degree 500, saponification degree 80%) = 1.6 × 10 ⁻² mol / g
Polyvinyl alcohol (average polymerization degree 1000, saponification degree 80%) = 1.6 × 10 ⁻² mol / g
Polycarboxylic acid pyromellitic acid = 1.6 x 10 ^-2 mol / g
Melitic acid = 1.8 × 10 ⁻² mol / g
Malonic acid = 1.9 x 10 ^-2 mol / g
Amine Diethylenetriamine = 4.0 × 10 ^-2 mol / g
Hydrazide Adipic acid dihydrazide = 1.1 × 10 ^-2 mol / g

  When blending such a curable prepolymer, a curing agent and a polymerization initiator for curing the prepolymer can be blended as necessary. The kind of these hardening | curing agents and a polymerization initiator can be suitably selected according to the kind of prepolymer to mix | blend. As such a curing agent and polymerization initiator, a compound that initiates a reaction by energy rays can be preferably used. For example, a photo radical polymerization resin of an acrylic monomer / oligomer, a photo-michael addition resin of a polyene-thiol curing system, a photo cationic polymerization resin of an epoxy, oxetane, and a vinyl ether monomer / oligomer can be exemplified. Moreover, various well-known photoreaction sensitizers can also be used for these formulations. By using such a photocurable resin, the shape after formation or after printing can be quickly fixed.

  Insulating inorganic components with fluidity that can be solidified include various metal alkoxides, various metal chlorides, water glass, colloidal silica, various silicon oxides, silicon nitrides, silicon fluorides, metal oxides, metals It is possible to use solutions of nitrides, metal silicides, metal phosphates, or these fine powders that are flowable.

  Such a fluid substance containing an inorganic component can be solidified by using a sol-gel reaction, high-temperature baking, or the like, and a sol-gel reaction catalyst can be blended with the fluid substance.

  As a catalyst for the sol-gel reaction, an inorganic component is hydrolyzed and polycondensed; an acid such as hydrochloric acid; an alkali such as sodium hydroxide; an amine; or dibutyltin diacetate, dibutyltin dioctate, dibutyltin dilaurate, Organotin compounds such as dibutyltin dimaleate, dioctyltin dilaurate, dioctyltin dimaleate, tin octylate; isopropyl triisostearoyl titanate, isopropyl tris (dioctyl pyrophosphate) titanate, bis (dioctyl pyrophosphate) oxyacetate titanate, tetraalkyl titanate Organic titanate compounds such as tetrabutyl zirconate, tetrakis (acetylacetonate) zirconium, tetraisobutyl zirconate, butoxy tris (acetate) Organozirconium compounds such as ruacetonate) zirconium and zirconium naphthenate; Organoaluminum compounds such as tris (ethylacetoacetate) aluminum and tris (acetylacetonato) aluminum; Organometallic catalysts such as zinc naphthenate, cobalt naphthenate and cobalt octylate Etc. Among these, a dibutyltin compound (SCAT-24 manufactured by Sansha Machinery Chemical Co., Ltd.) can be specifically mentioned as a commercial product. These compounds can be used alone or in combination of two or more.

  These organic components and inorganic components can be used as needed alone or in combination of organic and inorganic as appropriate.

  When a conductive composition is made by combining particles of insulating material that can be solidified with fluid and conductive particles, wetting of the conductive particles by the insulating material is different from the case where the insulating material is liquid. Since there is no coating by the conductive particles, the resistance value of the conductive composition which can be easily brought into contact with each other can be reduced. As a means for eliminating the fluidity of the particles of the insulating material and solidifying it, any means such as baking or compression fixation can be used.

  In the case of cooling and solidifying an insulating material in a molten state, it is advantageous when solidification speed is high and mass production is required because it can be solidified from a fluid state. In addition, when the melting temperature is lower than the foaming temperature, foaming can be performed quickly and efficiently, and the breakage of a fluid substance accompanying foaming and the generation of fragments associated therewith can be prevented.

  When a resin is used as a liquid insulating material that is cured by active energy rays, heat is less generated than heat curing, and therefore, a material that is weak against heat or a foamable substance having a low foaming temperature can be used. Examples of active energy rays include ultraviolet rays and electron beams. Moreover, when irradiating an active energy ray, it is not limited to the atmosphere, It can irradiate in various atmospheres and temperature environments, such as air | atmosphere, inert gas, such as nitrogen and argon, and a vacuum.

  As the liquid insulating material that is solidified by heating, a wide variety of materials such as a resin that is cured by heat, a resin that is solidified by solvent evaporation, and a metal oxide obtained by a sol-gel method can be used.

  Moreover, a well-known hot melt resin can be used for an insulating material.

  When the conductive composition having adhesiveness is used, the conductive composition can be used as a conductive adhesive. In this case, a safety device that can be used for conducting connection of the electronic device and at the same time can safely cut off the flow of electricity at the time of heat generation can be integrated in a simple and space-saving manner. Such adhesiveness can be imparted to the conductive composition by providing it to at least one or more materials constituting the conductive composition. A combination of liquid adhesive and conductive particles, insulation Can be used in a timely combination, such as a combination of conductive particles, a low melting point metal and a solvent, a combination of hot melt particles and conductive carbon material particles, and these materials can be used alone or in combination of two or more as required. Can be used.

  The conductive composition may further contain a solvent appropriately selected according to the blending components as necessary for adjusting the viscosity and imparting fluidity. Specific examples of such solvents include hydrocarbons (propane, n-butane, n-pentane, isohexane, cyclohexane, n-octane, isooctane, benzene, toluene, xylene, ethylbenzene, amylbenzene, turpentine oil, pinene, and the like). , Halogenated hydrocarbons (methyl chloride, chloroform, carbon tetrachloride, ethylene chloride, methyl bromide, ethyl bromide, chlorobenzene, chlorobromomethane, bromobenzene, fluorodichloromethane, dichlorodifluoromethane, difluorochloroethane, etc.), alcohol (methanol , Ethanol, n-propanol, isopropanol, n-amyl alcohol, isoamyl alcohol, n-hexanol, n-heptanol, 2-octanol, n-dodecanol, nonanol, cyclohexanol , Glycidol, etc.), ether, acetal (ethyl ether, dichloroethyl ether, isopropyl ether, n-butyl ether, diisoamyl ether, methylphenyl ether, ethylbenzyl ether, furan, furfural, 2-methylfuran, cineol, methylal), ketone (Acetone, methyl ethyl ketone, methyl-n-propyl ketone, methyl-n-amyl ketone, diisobutyl ketone, phorone, isophorone, cyclohexanone, acetophenone, etc.), ester (methyl formate, ethyl formate, propyl formate, methyl acetate, ethyl acetate, propyl acetate) , Acetate-n-amyl, methyl cyclohexyl acetate, methyl butyrate, ethyl butyrate, propyl butyrate, butyl stearate, etc.), polyhydric alcohols and their derivatives (ethylene glycol) , Ethylene glycol monomethyl ether, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether, methoxymethoxyethanol, ethylene glycol monoacetate, diethylene glycol, diethylene glycol monomethyl ether, propylene glycol, propylene glycol monoethyl ether, etc.), fatty acids and phenols (formic acid) , Acetic acid, acetic anhydride, propionic acid, propionic anhydride, butyric acid, isovaleric acid, phenol, cresol, o-cresol, xylenol, etc.), nitrogen compounds (nitromethane, nitroethane, 1-nitropropane, nitrobenzene, monomethylamine, dimethylamine , Trimethylamine, monoethylamine, diamylamine, aniline, monomethylaniline, o- Toluidine, o-chloroaniline, dicyclohexylamine, dicyclohexylamine, monoethanolamine, formamide, N, N-dimethylformamide, acetamide, acetonitrile, pyridine, α-picoline, 2,4-lutidine, quinoline, N-methylpyrrolidone, Morpholine, etc.), sulfur, phosphorus, other compounds (carbon disulfide, dimethyl sulfoxide, 4,4-diethyl-1,2-dithiolane, dimethyl sulfide, dimethyl disulfide, methanethiol, propane sultone, triethyl phosphate, tophenyl phosphate, (Diethyl carbonate, ethylene carbonate, amyl borate, etc.), inorganic solvents (liquid ammonia, silicone oil, etc.), water and the like.

  A stabilizer, a coupling agent, etc. can further be suitably selected and blended with the conductive composition as needed. Specific examples of such stabilizers include 2,6-di-tert-butyl-phenol, 2,4-di-tert-butyl-phenol, 2,6-di-tert-butyl-4-ethyl- Phenol-based antioxidants exemplified by phenol, 2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di-tert-butyl-anilino) -1,3,5-triazine and the like Agent, alkyldiphenylamine, N, N′-diphenyl-p-phenylenediamine, 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline, N-phenyl-N′-isopropyl-p-phenylenediamine, etc. Aromatic amine antioxidants, dilauryl-3,3′-thiodipropionate, ditridecyl-3,3′-thiodipropionate exemplified by A sulfide hydroperoxide decomposer exemplified by bis [2-methyl-4- {3-n-alkylthiopropionyloxy} -5-tert-butyl-phenyl] sulfide, 2-mercapto-5-methyl-benzimidazole and the like; Tris (isodecyl) phosphite, phenyl diisooctyl phosphite, diphenyl isooctyl phosphite, di (nonylphenyl) pentaerythritol diphosphite, 3,5-di-tert-butyl-4-hydroxy-benzyl phosphate diethyl ester , Phosphorus hydroperoxide decomposing agents exemplified by sodium bis (4-tert-butylphenyl) phosphate, etc., salicylates exemplified by phenyl salicylate, 4-tert-octylphenyl salicylate, etc. Benzophenone-based light stabilizers exemplified by 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid, etc., 2- (2′-hydroxy-5′-methylphenyl) Benzotriazole-based light exemplified by benzotriazole, 2,2′-methylenebis [4- (1,1,3,3-tetramethylbutyl) -6- (2N-benzotriazol-2-yl) phenol], etc. A hindered amine light stabilizer exemplified by a stabilizer, phenyl-4-piperidinyl carbonate, bis- [2,2,6,6-tetramethyl-4-piperidinyl sebacate] and the like, [2,2′- Exemplified by thio-bis (4-t-octylphenolate)]-2-ethylhexylamine-nickel- (II) Examples thereof include Ni-based light stabilizers, cyanoacrylate-based light stabilizers, and oxalic acid anilide-based light stabilizers. As such a coupling agent, specifically, as a fluorine-based silane coupling agent, (tridecafluoro-1,1,2,2-tetrahydrooctyl) triethoxysilane, an epoxy-modified silane coupling agent Coupling agent (trade name: KBM-403) manufactured by Shin-Etsu Chemical Co., Ltd., coupling agent (trade name: TESOX) manufactured by Toagosei Co., Ltd. as an oxetane-modified silane coupling agent, or vinyltrimethoxysilane, vinyltriethoxy Silane, γ-chloropropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N- (β-aminoethyl) -γ-aminopropyltrimethoxysilane, N- (β-aminoethyl) -γ-aminopropylmethyldimethoxy Silane, γ-glycidoxypropyltrimethoxysilane Silane coupling agents such as N, β-glycidoxypropylmethyldimethoxysilane, γ-methacryloxyxypropyltrimethoxysilane, γ-methacryloxyxypropylmethyldimethoxysilane, γ-mercaptopropyltrimethoxysilane, and triethanolamine Titanate, titanium acetylacetonate, titanium ethyl acetoacetate, titanium lactate, titanium lactate ammonium salt, tetrastearyl titanate, isopropyl tricumylphenyl titanate, isopropyl tri (N-aminoethyl-aminoethyl) titanate, dicumylphenyloxyacetate titanate, Isopropyltrioctanoyl titanate, isopropyl dimethacrylisostearoyl titanate, titanium lactate Ester, octylene glycol titanate, isopropyl triisostearoyl titanate, triisostearyl isopropyl titanate, isopropyl tridodecylbenzenesulfonyl titanate, tetra (2-ethylhexyl) titanate, butyl titanate dimer, isopropyl isostearoyl diacryl titanate, isopropyl tri (dioctyl phosphate) ) Titanate, isopropyltris (dioctylpyrophosphate) titanate, tetraisopropylbis (dioctylphosphite) titanate, tetraoctylbis (ditridecylphosphite) titanate, tetra (2,2-diallyloxymethyl-1-butyl) bis (di) -Tridecyl) phosphite titanate, bis (dioctyl pyrophosphate) Oxyacetate titanate, bis (dioctyl pyrophosphate) ethylene titanate, tetra -i- propyl titanate, tetra -n- butyl titanate, and titanium-based coupling agents such as diisostearoyl ethylene titanate. These compounds can be used alone or in combination of two or more.

  By blending the above-described titanium-based coupling agent and / or silane coupling agent into the conductive composition for coating a battery current collector, it is reacted with a hydrogen bonding functional group contained in the conductive composition and further crosslinked. The density can be improved, and the mutual substitution reaction between the element constituting the active material and the element constituting the current collector can be further suppressed.

  When the conductive composition is a liquid, various surfactants can be contained in order to adjust the wetting. Examples of such surfactants include soaps, lauryl sulfate, polyoxyethylene alkyl ether sulfate, alkyl benzene sulfonate, polyoxyethylene alkyl ether phosphate, polyoxyethylene alkyl phenyl ether phosphate. Acid, N-acyl amino acid salt, α-olefin sulfonate, alkyl sulfate ester salt, alkyl phenyl ether sulfate ester salt, methyl taurate, and the like. Examples of amphoteric surfactants include alkyl diaminoethyl glycine hydrochloride, 2 -Alkyl-N-carboxymethyl-N-hydroxyethylimidazolinium betaine, lauryldimethylaminoacetic acid betaine, coconut oil fatty acid amidopropyl betaine, fatty acid alkyl betaine, sulfobetaine, amidoxide, etc. Nonionic (nonionic) surfactants include polyethylene glycol alkyl ester compounds, alkyl ether compounds such as triethylene glycol monobutyl ether, ester compounds such as polyoxysorbitan esters, alkylphenol compounds, and fluorine compounds. Examples thereof include silicone compounds and silicone type compounds. These compounds can be used alone or in combination of two or more.

  In order to improve mechanical strength and thermal characteristics, the conductive composition can be blended with various fillers as necessary within a range not impairing necessary conductivity. Insulating fillers include powders of metal oxides such as alumina, silica, zirconia and titania, sols such as colloidal silica, titania sol and alumina sol, clay minerals such as talc, kaolinite and smectite, and carbides such as silicon carbide and titanium carbide. Nitrides such as silicon nitride, aluminum nitride and titanium nitride, borides such as boron nitride, titanium boride and boron oxide, complex oxides such as mullite, hydroxides such as aluminum hydroxide and magnesium hydroxide, etc. And barium titanate that can increase the dielectric constant of the composition.

  The foaming material is added in an amount necessary for the conductive composition to be insulative by foaming, that is, at least to have a higher electrical resistance than before foaming, or to be in a state where substantially no current flows under use conditions. To do. This amount is the type of conductive material, particle size, shape, etc., type of foamable material, particle size, shape, etc., foaming temperature, rate of temperature rise to foaming temperature, holding time at foaming temperature, pressure in foaming environment Depends on the amount of moisture in the foaming environment, etc., especially depending on the type of conductive particles, the type of foaming material, and the foaming temperature, but the change in electrical resistance can be easily measured by measuring the resistance before and after foaming. Can be sought.

  As an example, when using silver powder as a conductive material, a substance that decomposes and vaporizes at a predetermined temperature into a foamable substance (for example, sodium bicarbonate), and a synthetic resin (for example, an epoxy resin) as an insulator Is preferably 0.1 to 0.8 parts by weight, more preferably 0.16 to 0.24 parts by weight of the foamable material with respect to 1 part by weight of the conductive material. In the following example, the conductive material is silver powder, and the foaming material is a softening material that softens at a predetermined temperature or higher and is coated with a material that is chemically decomposed and vaporized at a predetermined temperature (for example, Nippon Philite) Co., Ltd., trade name: EXPANCEL), when using a synthetic resin (for example, epoxy resin) as an insulator, the foaming material is preferably 0.3 to 0.5 with respect to 1 part by weight of the conductive material. Parts by weight, more preferably 0.36 to 0.44 parts by weight. As another example, the conductive material is silver powder, the foamable material is a softening material that softens at a predetermined temperature or more, and the material that is chemically decomposed and vaporized at a predetermined temperature is coated with the softening material. (For example, Nihon Philite Co., Ltd., trade name: EXPANCEL) further coated with a conductive material (for example, nickel-phosphorous plating), and when using a synthetic resin (epoxy resin) for the insulator, the conductive material Preferably, the foamable material is 0.4 to 1.6 parts by weight, more preferably 0.4 to 0.6 parts by weight with respect to 1 part by weight. In the above example, the amount of synthetic resin added is preferably 0.1 to 0.2 parts by weight.

  The conductive composition of the present invention can be obtained as a solution or a suspension by mixing and stirring the above components. Stirring can be performed by appropriately selecting various stirring devices such as a propeller mixer, a planetary mixer, a hybrid mixer, a kneader, a homogenizer for emulsification, and an ultrasonic homogenizer. Moreover, it can also stir, heating or cooling as needed.

  Next, application and use of the conductive composition of the present invention will be described.

  An electric circuit and an electronic device including the electric circuit can be manufactured using the conductive composition of the present invention. In these electric circuits and electronic devices, when the temperature rises above a predetermined temperature, the foamable material foams, whereby the conductive composition becomes insulative, and the current can be safely interrupted. Further, among the conductive compositions, the type having fluidity that can be solidified can provide a solidified product having a free shape, so that an electric circuit or an electronic device can be easily formed. Furthermore, when the conductive composition has adhesiveness, the conductive connection and the safety mechanism can be integrated together. Examples of electrical circuits include those in which electrical elements such as inductors, capacitors, and switches are electrically connected by wires and electrodes. The conductive composition of the present invention is used for its constituent materials and conductive connection. It can be used as a wiring, an electrode, or a conductive adhesive. Examples of electronic devices including electric circuits and products equipped with electronic devices include refrigerators, microwave ovens, electric fans, washing machines, air conditioners, vacuum cleaners, TVs, personal computers, and cars, trains, aircraft, spacecrafts, etc. Can be mentioned.

  By covering the conductive composition or electric circuit that forms this electric circuit with a flexible elastic body below the foaming temperature of the foamable material, the conductive composition broken by foaming is prevented from falling off the electric circuit. Therefore, it is possible to prevent an accident such as a short circuit from occurring due to conductive fragments entering the electronic device.

  By covering the current collector and the electrode with the conductive composition of the present invention, it is possible to produce a current collector and an electrode that block current at a predetermined temperature. That is, it is possible to simply install a safety mechanism that cuts off the current in the portion where abnormal heat generation occurs on the entire surface of the current collector or electrode coated with the conductive composition.

  With this current collector or electrode, it is possible to produce electronic devices such as capacitors such as electric double layer capacitors that interrupt current when abnormal heat is generated, batteries such as secondary batteries such as Li ion batteries and Li ion polymer batteries. it can.

  A battery or a capacitor is generally manufactured to have a large electrode area because the electrode area determines its electric capacity and / or efficiency. Therefore, the present invention in which a safety device can be easily installed on the entire surface of the electrode can be preferably applied. In addition, since the current flow is blocked by foaming in the present invention, even when a short circuit occurs due to a conductive foreign material entering between the electrodes, the short circuit can be eliminated by pushing the foreign material up by expansion due to foaming.

  The electrode of the secondary battery coated with the conductive composition of the present invention can safely block the flow of current even if abnormal heat generation occurs at any part of the electrode during charging and discharging.

  A member made by conducting conductive connection of conductive materials in a lattice shape using the conductive composition having adhesiveness according to the present invention has an electric current because the conductive connection portion breaks and becomes insulating when the temperature exceeds a predetermined temperature. Can be safely shut off. By forming the conductive material so as to cover the solid body, it is possible to incorporate the safety mechanism easily and inexpensively over a wide range.

  The member assembled using the conductive composition having adhesiveness of the present invention can generate Joule heat and foam a foamable substance by energizing the conductive composition when it is necessary to disassemble it. The member can be easily dismantled from the portion of the conductive composition. Furthermore, since it is not necessary to heat the entire member, it can be applied to a member containing a material that is weak against heat, and since it is locally heated, energy efficiency is high. Examples of batteries incorporating a current collector coated with the conductive composition for coating a current collector of the present invention include primary batteries such as manganese dry batteries, silver oxide batteries, mercury batteries, lithium batteries, and lead storage batteries. Electrical properties can be improved by using secondary batteries such as lithium ion secondary batteries and nickel / zinc storage batteries, dye-sensitized solar cells, electric double layer capacitors, fuel cells, and the like.

  Examples of embodiments according to the conductive composition of the present invention and an electronic device using the conductive composition will be described below with reference to diagrams and tables such as schematic diagrams. It is not limited to.

  The 1st embodiment of the electrically conductive composition of this invention is forming the member which comprises an electronic device simply by solidifying an electrically conductive composition in arbitrary shapes. When the electronic device abnormally generates heat, the conductive composition becomes an insulator, so that the current flowing to the electronic device through the conductive composition can be safely interrupted.

  By foaming the foamable material in the conductive composition by the above method, the current can be safely interrupted as shown in the schematic diagram of FIG.

  Here, FIG. 1 is an example schematically showing a conductive composition in which a foamable substance 2 is contained in a conductive material 1, (a) before foaming, (b) after foaming due to abnormal heat generation. Show.

  As shown in FIG. 1 (a), the conductive material before foaming is united and can be energized to the left and right. However, as shown in FIG. The material is broken in the left-right direction by the foam 3 of the foamable material, and the current is cut off.

  Next, FIG. 2 is an example schematically showing a conductive composition in which a foamable material is contained in a flexible material at a temperature lower than the foaming temperature. FIG. Then, the state when the temperature drops and the stress in the direction of the arrow is applied from the outside (right figure), (b) is the state where the foaming material covered with a soft softening material below the foaming temperature is foamed ( (Left figure) and an example showing the state (right figure) when the temperature drops and stress in the direction of the arrow is applied from the outside.

  As shown in FIG. 2A, when the fractured portion of the conductive material broken as a result of foaming is the gap 3, when the external stress 4 is applied, the fractured surfaces 5 come into contact with each other and the conductivity is restored. On the other hand, as shown in FIG. 2 (b), when the shell 6 of the softening substance that has cooled and hardened exists in the fractured portion of the conductive material generated as a result of foaming, it is easily conductive even when external stress is applied. If the softening material is an elastic body at a softening temperature or lower, the shell 6 of the softening material can relieve stress and prevent electrical contact.

  In the following embodiment of the conductive composition of the present invention, the conductive composition contains a solidifiable insulating material having fluidity with the conductive particles, and before or after the insulating material is solidified. Conductivity is imparted by bringing particles having conductivity into contact with each other. In this case, foaming of the foamable material prevents the conductive particles from contacting each other, and the conductive composition can be changed to insulating.

  Here, FIG. 3 is a schematic diagram (left figure) of the composite material in which the foamable substance 2 is composited in the insulator 8 given conductivity by contact between the conductive particles 7. It is an example which showed a mode (right figure) that the contact between the particles which have electroconductivity is prevented by.

  As shown in FIG. 3, the conductive composition can be changed to insulating properties by preventing contact of conductive particles by foaming and opening the gap 9. Since it can change to an insulator by preventing the contact between particles having conductivity, it is not necessary to break the entire conductive composition, and the amount of the foaming substance added can be reduced.

  Next, FIG. 4 shows the orientation of the particles 10 in the conductive composition including the conductive particles 10 having a flat shape oriented in the electric field and / or the magnetic field, the foamable material 2 and the insulating material 8. It is a schematic diagram (left figure) of the conductive composition that is brought into contact with each other and given conductivity, and shows an example (right figure) in which the orientation of particles having conductivity is disturbed by foaming. is there.

  As shown in FIG. 4, as a result of foaming, the orientation of the conductive particles in orientation contact is disturbed, the contact is hindered, and the conductive composition can be changed to insulating by leaving a gap. That is, the conductive composition can be more reliably changed to an insulator by disturbing the orientation of the conductive particles and generating voids by foaming.

Here, the magnetic field (magnetic field) H (unit: AT / m = ampere-turn / meter) in the present invention refers to a vortex-like field generated by the movement of electric charges, and exerts a force on the movement of electric charges. The strength of the magnetic field is represented by magnetic flux density B (unit: T = Tesla), and is the number of magnetic lines Φ (unit: Wb = Weber) penetrating the area S (m ² ) perpendicular to the magnetic field divided by the area. .

[Formula 2]
Formula 2 B = Φ / S (Wb / m ² = T)

  Such a magnetic field can be generated by passing an electric current as in an electromagnet, or can be generated by aligning the direction of the magnetic moment of an electron spin of a substance as in a permanent magnet. Further, the magnetic flux density B and the magnetic field H can be expressed by the following relational expression in a vacuum.

[Formula 3]
Formula 3 B = μ ₀ H

Here, μ ₀ is the permeability of vacuum, rational unit is 4π × 10 ⁻⁷ (Henry / meter = H / m), non-rational unit is 1 (anonymous number), and magnetic flux density B and magnetic field strength H are It is a coefficient to tie. Further, the magnetic permeability K (Henry / meter = H / m) is obtained by dividing the ratio μ between the magnetic flux density B and the magnetic field strength H when a substance is placed in a magnetic field by μ ₀ .

[Formula 4]
Equation 4 K = μ / μ ₀

  The strength of the interaction of the material by the magnetic field is indicated by the magnetic susceptibility χ, and the larger the absolute value, the stronger the magnetic field is induced in the material, causing a strong magnetic interaction with the induced magnetic field. The above-described magnetic permeability K is a non-rational unit and the following relational expression is established.

[Formula 5]
Formula 5 K = 1 + χ

  In the following explanation, unless otherwise specified, the magnetic susceptibility χ is shown in a non-rational unit. Next, Table 1 shows the magnetic anisotropy of typical substances. The examples shown here are magnetic anisotropy derived from the crystal structure, but artificially magnetic anisotropy, such as fibers obtained by stretching polymers and materials combining different magnetic susceptibility, etc. The material can be oriented by applying an appropriate magnetic field to a material having a shape or a material having shape anisotropy.

  The interaction between the magnetic field and the substance is determined by the strength of the magnetic field and the absolute value of the magnetic susceptibility χ, and the force to align the axis where the magnetic field is strong and the absolute value of the magnetic susceptibility χ is large is parallel to the magnetic field. Which direction it is actually oriented (easy magnetization axis) is determined by the balance of the three-axis magnetic anisotropy of the crystal.

  Also, magnetic anisotropy means that there is anisotropy in a substance with respect to magnetization excited by an external magnetic field. In the magnetic field, torque is generated by magnetic interaction, and in a more stable direction. Rotate. Substances that have anisotropy in the molecular structure also have magnetic anisotropy. For example, in a fiber made by drawing, molecular chains are aligned in the drawing direction, so the fiber direction (//) and perpendicular to it The magnetic susceptibility differs in the direction (率). When the fiber exhibits diamagnetism, the difference is called diamagnetic anisotropic magnetic susceptibility (χa), and is represented by the difference in magnetic susceptibility with respect to an arbitrary axis.

[Formula 6]
χ _a = χ // − χ⊥

When a diamagnetic material having such magnetic anisotropy is placed in a magnetic field of strength B, the material acquires magnetic energy E.

Here, μ ₀ is the vacuum permeability, V is the volume of the object, θ is the angle between the magnetic field and the fiber axis direction, and B is the external magnetic field strength.

When χ _a > 0, the magnetic energy becomes smaller and more stable when the fiber axis direction is parallel to the magnetic field. As a result, it is oriented parallel to the magnetic field.

  Such a uniaxially oriented fiber can be described as described above. On the other hand, the direction of orientation of substances having different magnetic anisotropy in three axes is spatially determined. In this case, the direction in which the substance is oriented with respect to the external field is determined from the value of the triaxial magnetic anisotropy.

  It can also be seen from the formula that when the external magnetic field is large and when the volume is large, the magnetic energy is received more strongly.

  Some substances having magnetic anisotropy have anisotropy in the electronic state in the substance. In the case of the fibers described above, anisotropy occurs in the flow of electrons through the bonds by arranging the molecules in the stretched direction. A substance having anisotropy in the crystal structure is also oriented in the magnetic field. On the other hand, even when there is no magnetic anisotropy, the material is oriented if it has anisotropy.

  A layered compound such as clay or graphite can also be exemplified as a substance having a large magnetic anisotropy, and crystals can be directed in an arbitrary direction by applying an appropriate magnetic field.

  When a magnetic field is applied to such a substance, it is oriented in a magnetically stable direction. For example, when a magnetic field that rotates uniaxially is applied to a material having magnetic anisotropy, the hard axis of magnetization of the substance with respect to the rotation axis is the magnetic field. Oriented parallel to the rotation axis. In addition, as described above, the magnetic field applied to the substance having magnetic anisotropy can be a magnetic field in which the application direction and strength of the magnetic field vary with time, including the rotating magnetic field.

  The behavior of a material having magnetic anisotropy in a magnetic field has been described above, but the behavior of a material having dielectric anisotropy in an electric field can also be explained by the same principle.

  Of the substances that perform such magnetic field orientation, for insulating substances, the surface is coated with a conductive substance to such an extent that the magnetic anisotropy is not lost, or a conductive material is combined. can do.

  When a material having magnetic and / or dielectric anisotropy is oriented in one or both of magnetic and / or electric fields in a fluid material, it is necessary to overcome random rotational motion and viscous resistance derived from thermal energy. There is. In order to orient a substance having a small magnetic and / or dielectric anisotropy, it is advantageous to use a strong magnetic field and / or electric field, and the process can be completed in a short time by using a low-viscosity fluid. You can also.

  Moreover, it is preferable to orient using one or both of a magnetic field and an electric field in a fluid material having a specific gravity adjusted so that a material having magnetic and / or dielectric anisotropy does not settle.

  Even a conductive material having no magnetic anisotropy as described above can be oriented using an induced magnetic field. For example, since most metals are cubic and have no magnetic anisotropy, they cannot be magnetically oriented with a normal static magnetic field. On the other hand, by using a time-varying magnetic field, a conductive material having no such magnetic anisotropy can be magnetically oriented. As used herein, “time-varying magnetic field” refers to a magnetic field in which the amount of magnetic flux penetrating the conductive material changes with time. More specifically, by applying a time-varying magnetic field to the conductive material, an induced current is generated in the conductive material, and the induced current generates an induced magnetic field in a direction that cancels the change in magnetic flux. At this time, a magnetic interaction occurs between the induced magnetic field and the time-varying magnetic field, and the conductive material moves or rotates in a direction in which the change in magnetic flux is reduced. If orientation using an induced magnetic field is used, even a material having no magnetic anisotropy can be oriented as long as it has conductivity. For example, when a uniaxial rotating magnetic field is applied to rod-shaped metal particles, the long axis of the rod and the axis of the rotating magnetic field are arranged in parallel. When a uniaxial rotating magnetic field is applied to the disk-shaped metal particles, the normal line of the disk and the axis of the rotating magnetic field are arranged in parallel. Such an orientation using an induced magnetic field can be used for a cubic metal having no magnetic anisotropy, so that the range of application is wide and the opportunity to select a material suitable for the characteristics of the electronic device increases.

  As another method of orienting a conductive material having no magnetic anisotropy, a method of orienting and attaching a substance having anisotropy to a conductive material having no magnetic anisotropy can be used. In this case, the conductive material having no magnetic anisotropy can be indirectly magnetically oriented by the anisotropy of the substance having anisotropy attached to the orientation. For example, a flat-shaped metal particle having no magnetic anisotropy in which a surfactant is aligned and adhered by the intermolecular force can be aligned even in a static magnetic field due to the magnetic anisotropy of the surfactant. When the photocurable resin is used as an insulator having fluidity, the photocurability in the oriented direction can be improved by orienting the conductive material in this way.

  Next, the aspect of the application example of the electrically conductive composition of this invention is demonstrated. FIG. 5A is a schematic view when the electronic device is assembled by electrically connecting the device 12 to the wiring 13 with the conductive composition layer 11 having adhesiveness, and FIG. It is a schematic diagram of the prior art example at the time of separately incorporating it into an electronic device using a normal conductive adhesive 16.

  As shown in FIG. 5B, when the safety device 15 is separately incorporated, a safety device, a space for incorporating the safety device, and an assembling process are required. As shown in FIG. 5 (a), by using the conductive composition having adhesiveness according to the present invention, it is possible to simultaneously achieve the conductive connection and the incorporation of the safety mechanism. By changing the conductive composition layer 11 to be insulative, the flow of electricity to the device can be safely interrupted.

  Next, an embodiment of a lithium ion secondary battery having an electrode coated with the conductive composition of the present invention will be described. An electrode coated with a conductive composition is capable of safely interrupting the flow of current in any part of the electrode during charging / discharging, so the energy density is high and the risk of heat generation is high It can be particularly preferably used for a lithium ion secondary battery.

  Here, FIG. 6 shows a schematic view in which the conductive composition layer 11 having adhesiveness and the active material layer 18 made of a mixture of the active material and the binder are applied to the surface of the current collector 17 of the anode. A case is shown in which a conductive foreign material 21 exists between the current collector 17 and the active material layer 18 and the cathode current collector 19 and the graphite layer 20 through the separator 22 and is short-circuited (left figure).

As shown in FIG. 6, when the conductive foreign material 21 breaks through the separator 22 and is short-circuited to cause abnormal heat generation, the foamable substance in the conductive composition layer 11 at the heat generation portion is foamed and the abnormal heat generation is reduced. The conductive composition layer 23 after foaming, which is an insulating material, pushes up the foreign material and the anode current collector 17 at the heat generation site, and the abnormal heat generation due to the short circuit and the short circuit can be eliminated (right figure). Furthermore, by providing the conductive composition layer 11 as a buffer band between the active material layer 18 on the anode side and the current collector 17, deterioration due to mutual migration between atoms of the current collector 17 and lithium atoms is prevented. It is also possible to prevent a decrease in adhesion and / or a decrease in electrical characteristics due to generation.
Such a foaming agent can also be blended in the active material layer. From the viewpoint of conductivity, it is preferable to use a conductive foaming agent, and an insulating foaming agent should be combined with a separator. Is also possible. In addition, when the abnormal heat generation part is local as in the above example, only the abnormal part can be made insulative, and the battery characteristics of the other electrode surfaces can be left as they are.

  Next, an embodiment of an electronic circuit manufactured using the conductive composition of the present invention will be described. FIG. 7 shows a schematic cross-sectional view (a) and a schematic top view (b) when the wirings 17 and 25 formed on the film 24 are conductively connected with a conductive composition having adhesiveness. As shown in FIG. 7B, in this electronic circuit, an adhesive conductive composition layer 11 is formed in a lattice shape to electrically connect the wirings 17 and 25. When the temperature exceeds a predetermined temperature, the electronic circuit is electrically connected. The current can be safely interrupted by breaking the part to become insulating.

  As shown in FIG. 7B, by forming a series circuit with a single stroke, a safety device capable of interrupting current even if there is a part of abnormal heat generation in a wide range is easily produced. be able to.

  As described above, the first function of the member using the conductive composition of the present invention is conductivity, and can be used in places where electricity flows, such as wiring and joints. The second function is foaming, and the conductive composition is broken by expansion due to foaming and can be turned into an insulator to stop the flow of electricity. Furthermore, by using a conductive composition having fluidity that can be solidified as a third function, the conductive composition can be easily formed into a desired shape, and those having adhesive properties are electrically connected. Incorporation of safety devices can also be achieved at the same time. As described above, since the conductive member produced using the conductive composition of the present invention has a characteristic of changing to insulation when it reaches a predetermined temperature, it is a safety device that safely cuts off the flow of electricity during abnormal heat generation. Available for electronic devices.

  Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. The amount added is in parts by weight unless otherwise noted.

(Adhesive conductive composition containing a foaming substance that is chemically decomposed and vaporized)
In Example 1, using an adhesive conductive composition containing a foamable substance that is chemically decomposed and vaporized, an electronic device was manufactured in which current was interrupted when the temperature reached a predetermined temperature or higher.

(Production of an adhesive conductive composition containing a foamable substance that is chemically decomposed and vaporized)
50 parts of bisphenol A type epoxy resin (product name: Epicron 850) manufactured by Dainippon Ink & Chemicals, Inc., 10 parts of alicyclic epoxy resin (product name: Celoxide 2021P) manufactured by Daicel Chemical Industries, Ltd., Sanshin Chemical Industry Co., Ltd. 5 parts of photothermal cation initiator (product name: Sun-Aid SI-100L), 5 parts of epoxy-modified silane coupling agent (product name: KBM-403) manufactured by Shin-Etsu Chemical Co., Ltd., silver powder (Fukuda Metal Foil Powder Co., Ltd.) Product name: AgC-A) 500 parts, foaming substance (sodium hydrogencarbonate fine powder) 100 parts in a planetary mixer with cooling jacket, stir until uniform liquid, chemically decomposed and foamed An adhesive conductive composition containing the material was obtained. At this time, stirring was performed while cooling the solution so as not to exceed 25 ° C. so that the coating solution did not react with heat generated during stirring.

(Manufacture of electronic devices)
The conductive composition was applied on a copper electrode, and a test silicon chip (10 × 10 × 0.3 mm) was pressed thereon and cured by heating at 100 ° C. for 1 hour. When the continuity between the copper electrode and the silicon chip was confirmed using a tester, the continuity could be confirmed.

(High temperature environment test)
When the silicon chip conductively bonded to the copper electrode described above was heated at 150 ° C. for 10 minutes, it was confirmed that the foamable substance in the conductive composition after solidification was foamed and the silicon chip was floating. When the continuity between the copper electrode and the silicon chip was confirmed using a tester, the continuity could not be confirmed.

(Push test)
When the silicon chip, which could not be confirmed to be conductive, was pressed against the copper electrode with a load of 1 kg, the conduction with the copper electrode was confirmed using a tester, and the conduction was confirmed.

(Adhesive conductive composition containing a foamable material coated with a softening material)
In Example 2, using an adhesive conductive composition containing a foamable material coated with a softening material, an electronic device was manufactured in which the current was interrupted when the temperature exceeded a predetermined temperature.

(Production of an adhesive conductive composition containing a foamable material coated with a softening material)
50 parts of bisphenol A type epoxy resin (product name: Epicron 850) manufactured by Dainippon Ink & Chemicals, Inc., 10 parts of alicyclic epoxy resin (product name: Celoxide 2021P) manufactured by Daicel Chemical Industries, Ltd., Sanshin Chemical Industry Co., Ltd. 5 parts of photothermal cation initiator (product name: Sun-Aid SI-100L), 5 parts of epoxy-modified silane coupling agent (product name: KBM-403) manufactured by Shin-Etsu Chemical Co., Ltd., silver powder (Fukuda Metal Foil Powder Co., Ltd.) Product name: AgC-A) 510 parts, 180 parts of foamable material (product name: EXPANCEL 920DU40) manufactured by Nippon Philite Co., Ltd. put in a planetary mixer with cooling jacket, stirred until uniform liquid and coated with softening substance An adhesive conductive composition containing the foamable material thus obtained was obtained. At this time, stirring was performed while cooling the liquid temperature in a range not exceeding 25 ° C. so that the coating liquid did not react with heat generated during stirring.

(Manufacture of electronic devices)
The conductive composition was applied on a copper electrode, and a test silicon chip (10 × 10 × 0.3 mm) was pressed thereon and cured by heating at 100 ° C. for 1 hour. When the continuity between the copper electrode and the silicon chip was confirmed using a tester, the continuity could be confirmed.

(High temperature environment test)
When the silicon chip conductively bonded to the copper electrode was heated at 150 ° C. for 10 minutes, it was confirmed that the foamable substance in the conductive composition after solidification foamed and the silicon chip was floating. When the continuity between the copper electrode and the silicon chip was confirmed using a tester, the continuity could not be confirmed.

(Push test)
In a state where the silicon chip that could not be confirmed for conduction was pressed against the copper electrode side with a load of 1 kg, conduction with the copper electrode was confirmed using a tester, and conduction could not be confirmed.

(Adhesive conductive composition containing foamed material plated with silver)
In Example 3, using an adhesive conductive composition containing a composite in which a foamable material coated with a softening material was silver-plated, an electronic device was manufactured in which the current was interrupted when the temperature exceeded a predetermined temperature.

(Manufacture of conductive composition containing foamed material plated with silver)
50 parts of bisphenol A type epoxy resin (product name: Epicron 850) manufactured by Dainippon Ink & Chemicals, Inc., 10 parts of alicyclic epoxy resin (product name: Celoxide 2021P) manufactured by Daicel Chemical Industries, Ltd., Sanshin Chemical Industry Co., Ltd. 5 parts of photothermal cation initiator (product name: Sun-Aid SI-100L), 5 parts of epoxy-modified silane coupling agent (product name: KBM-403) manufactured by Shin-Etsu Chemical Co., Ltd. Product name: AgC-A) 500 parts, silver-plated foamable material manufactured by Nihon Philite Co., Ltd. (product name: EXPANCEL 920DU40 with silver electroless plated) 250 parts in a planetary mixer with cooling jacket, uniform liquid The adhesive conductive composition containing a foaming substance plated with silver was obtained. At this time, stirring was performed while cooling the solution so as not to exceed 25 ° C. so that the coating solution did not react with heat generated during stirring.

(Manufacture of electronic devices)
The conductive composition was applied onto a copper electrode, a test silicon chip was pressed from the copper composition, and heat-cured at 100 ° C. for 1 hour. When the continuity between the copper electrode and the silicon chip was confirmed using a tester, the continuity could be confirmed.

(High temperature environment test)
When the silicon chip conductively bonded to the copper electrode described above was heated at 150 ° C. for 10 minutes, it was confirmed that the foamable substance in the conductive composition after solidification foamed and the silicon chip was floating. When the continuity between the copper electrode and the silicon chip was confirmed using a tester, the continuity could not be confirmed.

(Push test)
When conduction with the copper electrode was confirmed using a tester in a state in which the above-described silicon chip that could not be confirmed was pressed against the copper electrode with a load of 1 kg, conduction was not confirmed.

(Conductive composition whose conductive material is solder)
In Example 4, an electronic device in which the flow of electricity was cut off at an arbitrary temperature or higher was manufactured using a conductive composition whose conductive material was solder.

(Manufacture of conductive composition whose conductive material is solder)
50 parts of Sn-Bi-In solder particles having a particle size of 50 μm and melting point of 80 ° C. and nickel-phosphorus-plated foaming material manufactured by Nihon Philite Co., Ltd. (product name: EXPANCEL920DU40 electrolessly plated with nickel-phosphorous) 20 Part was dispersed in 30 parts of a solvent (NMP) to prepare a conductive composition in which the conductive material was solder.

(Manufacture of electronic devices)
The conductive composition was applied onto a copper electrode, and heated from 90 ° C. for 10 minutes in a state where a test silicon chip was pressed thereon to melt the solder particles, and then cooled and solidified. When the continuity between the copper electrode and the silicon chip was confirmed using a tester, the continuity could be confirmed.

(High temperature environment test)
When the silicon chip conductively bonded to the copper electrode is heated at 150 ° C. for 10 minutes, the foamable material in the conductive composition is foamed, and the foamable material having a lighter specific gravity is separated from the solder. It was confirmed that the chip was floating. When the continuity between the copper electrode and the silicon chip was confirmed using a tester, the continuity could not be confirmed.

(Push test)
When conduction with the copper electrode was confirmed using a tester in a state in which the above-described silicon chip that could not be confirmed was pressed against the copper electrode with a load of 1 kg, conduction was not confirmed.

(Application to lithium-ion batteries)
In Example 5, using an electrode coated with a conductive composition, a lithium ion battery was manufactured in which current was interrupted when the temperature reached a predetermined temperature or higher. The manufacturing method used is shown in FIGS. 8A to 8D, which are cross-sectional views of a lithium ion battery.

  Here, the electrode shown in FIG. 8A was prepared by forming polyvinylidene fluoride (hereinafter referred to as PVDF) having a thickness of 50 μm in which 65% of graphite particles were dispersed in a copper foil 19 having a thickness of 20 μm. By inserting lithium ions generated at the anode between the graphite layers at the cathode, lithium ions can be received.

  The electrode shown in FIG. 8 (b) is an electrically conductive conductive material prepared by mixing 50 parts of carbon black and 30 parts of a foamable material plated with nickel-phosphorous on 40 parts of PVDF on an aluminum foil 17 having a thickness of 30 μm. The active material layer 18 (thickness: 50 μm) is formed on the active composition layer 11 (thickness: 5 μm), on which 85 parts of lithium cobaltate and 5 parts of carbon black are combined with 10 parts of PVDF.

  The lithium ion battery shown in FIG. 8C has a polyethylene porous film impregnated with a dimethyl carbonate solution containing 5% lithium hexafluorophosphate sandwiched between (a) and (b). Thus, by applying an electric field in the vertical direction, lithium ions move and charge / discharge can be performed.

When heated in this state at 150 ° C. for 1 minute, as shown in FIG. 8D, the conductive composition layer 11 foams and changes to the insulator layer 23, and at the same time, the current collector 17 and the active material layer 18. By separating the current, the current from the current collector 17 to the active material layer 18 can be cut off.
FIG. 9 is a cross-sectional photograph showing a state where the aluminum foil 17 and the active material layer 18 are peeled off by foaming of the conductive composition layer 11.

  As described above, by manufacturing an electronic device using the foamable conductive composition of the present invention, current can be safely interrupted during abnormal heat generation. Since such a conductive composition can be formed from a fluid material, a conductive member can be easily produced, and the number of steps can be reduced by conducting a conductive connection. Since it can be applied, it can also be used as a safety device against abnormal heat generation of lithium ion batteries, which has become a problem in recent years.

(Adaptation to lithium-ion batteries)
(Manufacture of conductive composition for battery current collector coating)
As a curable component having a hydrogen bondable functional group value of 1.0 to 5.0 × 10 ⁻² mol / g, polyvinyl alcohol having an average polymerization degree of 500 and a saponification degree of 80% manufactured by Kuraray Co., Ltd. (product name: Kuraray) Poval PVA205: hydrogen bonding functional group value = 1.8 × 10 ⁻² mol / g) 30 parts, conductive carbon black (product name: Denka Black granular product) 50 parts manufactured by Denki Kagaku Kogyo Co., Ltd. as a conductive material, solvent NMP (500 parts) was stirred with heating at 80 ° C. for 120 minutes using a dispar mill. After returning to room temperature, pyromellitic acid (hydrogen bonding functional group value = 1.6 x 10 ^-2 mol / g) as a curable component with a hydrogen bonding functional group value of 1.0 to 5.0 x 10 ^-2 mol / g 400 parts of NMP in which 20 parts were dispersed was added, stirred for 10 minutes with a planetary mixer while cooling, and further dispersed using a bead mill until the average particle size of carbon black was 300 nm or less.

(Collector current collector)
The above-described conductive composition was coated on an aluminum current collector to a thickness of 300 nm to 500 nm using a spin coater, and was cured by heating at 230 ° C. for 10 seconds.

(Preparation of negative electrode)
A mixed solution in which 20 parts of graphite was mixed with 100 parts of a 20% PVDF N-methylpyrrolidone solution on a 20 μm thick copper foil was coated to form a film thickness of 50 μm after drying N-methylpyrrolidone, and dried at 160 ° C. for 2 hours. A negative electrode was produced.

(Preparation of positive electrode)
The aluminum current collector coated with the conductive composition prepared earlier, 100 parts of a 20% PVDF N-methylpyrrolidone solution, 170 parts of lithium cobaltate particles (average particle size 1 μm), as a conductive material A mixed liquid in which 10 parts of conductive carbon black (product name: Denka black granular product) manufactured by Denki Kagaku Kogyo Co., Ltd. was uniformly dispersed was applied and formed so as to have a film thickness of 50 μm after drying N-methylpyrrolidone. A positive electrode was produced by drying for a period of time.

(Battery assembly)
A nonwoven fabric made of cellulose (porosity 60%) having a thickness of 100 μm impregnated with a 5% dimethyl carbonate solution of lithium hexafluorophosphate is sandwiched between the negative electrode and the positive electrode produced by the above method and cut into 4 cm square, and further An aluminum laminate pack was used to produce a battery cell.

(Adaptation to lithium-ion batteries)
(Production of conductive composition for battery current collector coating; addition of silane coupling agent as a crosslinking agent)
As a curable component having a hydrogen bonding functional group value of 1.0 to 5.0 × 10 ⁻² mol / g, 30 parts of polyvinyl alcohol (product name: Kuraray Poval PVA205) with an average polymerization degree of 500 manufactured by Kuraray Co., Ltd., Shin-Etsu Chemical Co., Ltd. Epoxy-modified silane coupling agent (product name: KBM-403: hydrogen bonding functional group value = 0 mol / g) manufactured by Denki Kagaku Kogyo Co., Ltd., conductive carbon black (product name: DENKA) Black granular product) 50 parts and 500 parts of NMP as a solvent were stirred with heating at 80 ° C. for 120 minutes using a dispar mill. After returning to room temperature, 400 parts of NMP in which 20 parts of pyromellitic acid is dispersed as a curable component having a hydrogen bond functional group value of 1.0 to 5.0 × 10 ⁻² mol / g is added with a planetary mixer while cooling. The mixture was stirred for 10 minutes and further dispersed using a bead mill until the average particle size of the carbon black was 300 nm or less.

(Collector current collector)
The above conductive composition was coated on an aluminum current collector to a thickness of 300 nm to 500 nm using a spin coater, and was cured by heating at 230 ° C. for 10 seconds.

(Preparation of negative electrode)
A mixed solution in which 20 parts of graphite was mixed with 100 parts of a 20% PVDF N-methylpyrrolidone solution on a 20 μm thick copper foil was coated to form a film thickness of 50 μm after drying N-methylpyrrolidone, and dried at 160 ° C. for 2 hours. A negative electrode was produced.

(Preparation of positive electrode)
The aluminum current collector coated with the conductive composition prepared earlier, 100 parts of a 20% PVDF N-methylpyrrolidone solution, 170 parts of lithium cobaltate particles (average particle size 1 μm), as a conductive material A mixed liquid in which 10 parts of conductive carbon black (product name: Denka black granular product) manufactured by Denki Kagaku Kogyo Co., Ltd. was uniformly dispersed was applied and formed so as to have a film thickness of 50 μm after drying N-methylpyrrolidone. A positive electrode was produced by drying for a period of time.

(Battery assembly)
A nonwoven fabric made of cellulose (porosity 60%) having a thickness of 100 μm impregnated with a 5% dimethyl carbonate solution of lithium hexafluorophosphate is sandwiched between the negative electrode and the positive electrode produced by the above method and cut into 4 cm square, and further An aluminum laminate pack was used to produce a battery cell.

(Adaptation to lithium-ion batteries)
(Curing the current collector coating while applying a magnetic field)
Except for applying a 1 T static magnetic field from the normal direction of the current collector using a superconducting magnet with a bore diameter of 1 m during curing of the current collector coating and drying of the negative electrode and positive electrode active material layers. A battery cell was produced in the same manner as in Example 7.

[Comparative Example 1]
Example 7 was the same as Example 7 except that the electrode was produced without forming a conductive coat on the battery current collector.

[Comparative Example 2]
The production of the conductive composition for coating the battery current collector was the same as in Example 7, and the film thickness of the coating agent was changed from 300 nm to 500 nm to 3 μm.
The battery cell manufacturing method was the same as in Example 7.

[Comparative Example 3]
(Manufacture of conductive composition for battery current collector coating; manufactured with substance having hydrogen bonding functional group value of 1.0 × 10 ^-2 mol / g or less)
Dainippon Ink & Chemicals, Inc. bisphenol A type epoxy resin (product name: Epicron 850: hydrogen bondable functional group value = 0 mol / g), Daicel Chemical Industries, Ltd. alicyclic epoxy resin (product name: Celoxide 2021P: hydrogen bondable functional group value = 0 mol / g) 10 parts, Shin-Etsu Chemical Co., Ltd. epoxy-modified silane coupling agent (product name: KBM-403), electrochemical industry as a conductive material 70 parts of conductive carbon black (product name: Denka black granular product) and 500 parts of NMP as a solvent were stirred with heating at 80 ° C. for 120 minutes using a dispar mill. After returning to room temperature, 5 parts of a photothermal cation initiator (product name: Sun-Aid SI-100L) manufactured by Sanshin Chemical Industry Co., Ltd. was added and stirred for 10 minutes with a planetary mixer while cooling. It was dispersed until the average particle size was 300 nm or less. At this time, stirring was performed while cooling the liquid temperature in a range not exceeding 25 ° C. so that the coating liquid did not react with heat generated during stirring.
Example 7 was the same as Example 7 except for the method for producing the conductive composition for battery current collector coating.

[Battery characteristics comparison test]
The charge / discharge capacity and the cycle test for each charge / discharge rate of the battery cells produced in Examples 6 and 7 and Comparative Examples 1, 2, and 3 were performed.

(Internal resistance measurement)
The initial impedance at 1 kHz was measured.

(Charge / discharge capacity)
The charge / discharge capacity per gram of active material was compared for each charge / discharge cycle. The charge / discharge cycle is tested between 3V and 4.2V, and the charge / discharge capacity is 1C, 3C, 10C, 30C when the charge / discharge rate (number of times of charge / discharge per hour) is 0.5C. Compared.

(Cycle test)
The charge / discharge cycle was tested between 3 V and 4.2 V, and the cycle life was determined when the charge / discharge capacity at 0.5 C was 70% or less compared to the initial value.

  By using the current collector protected with the conductive coating agents of Examples 6, 7, and 8, it was confirmed that the battery capacity was improved and the cycle life was improved. In particular, Example 7 has a longer life than Example 6 that does not contain a cross-linking agent, and Example 8 produced by orienting the magnetic field has a low internal resistance value, and it has become clear that it has a longer life.

The same effect can be confirmed with a conductive coating agent (Comparative Example 3) made of a material having a hydrogen bondable functional group value of 1.0 × 10 ⁻² mol / g or less, but the effect of improving the lifetime is extremely low. Further, the thickness of the conductive coating layer is appropriate to be 50 to 500 nm, and in Comparative Example 2, which is thicker than that, the result is worse than Comparative Example 1 in which the conductive coating layer is not formed.

[Electrode cross-section observation]
In the above cycle test, the cross sections of the positive electrode of Example 6, Comparative Example 1 and Comparative Example 2 after 100 cycles were prepared with a focused ion beam, and observed with a TEM and observed with an EELS (Electron Energy-Loss Spectroscopy) image. (FIG. 10).

  FIG. 10A shows a cross-sectional TEM image of each electrode. From this image, Comparative Example 1 has no conductive coating layer, Example 6 has a conductive coating layer of about 300 nm, and Comparative Example 2 has It can be seen that a conductive coating layer of about 3 μm is formed. FIG. 10B shows an EELS analysis performed so as to overlap the TEM image of FIG. 10A, and shows the distribution of aluminum elements in each electrode. From this image, an undercoat layer is formed. The movement of the aluminum element to the active material side which is not seen in Comparative Example 1 is not seen in Example 1 and Comparative Example 2 in which the undercoat is formed. FIG. 10 (c) is an EELS analysis performed so as to overlap with the TEM image of (a), and shows the carbon element distribution state of each electrode. The movement of is not seen. FIG. 10D shows an EELS analysis performed so as to overlap the TEM image of FIG. 10A, and shows the distribution of lithium elements in each electrode. From this image, an undercoat layer is formed. The movement of the lithium element to the aluminum current collector side and the movement of the aluminum element to the active material layer and the active material, which are not seen in Comparative Example 1, are not seen in Example 1 and Comparative Example 2 in which the undercoat is formed.

As described above, it has become clear from the TEM analysis that the mutual substitution reaction between aluminum and lithium can be prevented by providing the conductive undercoat layer. Such effects include a substance having a hydrogen-bonding functional group value of 1.0 to 5.0 × 10 ^-2 mol / g and a conductive material, and can be solidified and fluidized. A composition comprising 50% by weight or more of a substance having a hydrogen-bonding functional group value of 1.0 to 5.0 × 10 ⁻² mol / g in a solid excluding a conductive material after solidification. This is particularly noticeable for the conductive composition for coating a battery current collector.

  In addition, when the thickness of the conductive layer is too thick, the above mutual substitution reaction can be prevented, but it has also been clarified that the charge / discharge characteristics are lowered due to the increase in the internal resistance of the battery.

(A) is a figure which shows the state by which the foamable substance was compounded in the electroconductive substance. (B) is a figure which shows the state by which the electroconductive substance was fractured | ruptured by the foamable substance in an electroconductive substance foaming. (A) is a figure which shows the state which the torn surface has contacted by the electrically conductive substance fractured | ruptured as a result of foaming, and external stress. (B) is a figure which shows the state in which the contact of the torn surface by external stress is prevented by the softening substance which expanded as a result of foaming, and the shell consisting of the solidified softening substance. It is a figure which shows the mode before and behind foaming of the electroconductive composition which combined electroconductive particle and the foamable substance. It is a figure which shows the mode that the foaming substance foamed and the said orientation was disturb | confused, and the conductive composition containing the conductive particle and foamable substance which carried out orientation contact by the electric field or the magnetic field, or both. (A) is a schematic diagram of the electronic apparatus assembled by conducting and connecting devices with a foaming conductive adhesive. (B) is a schematic diagram of an electronic device assembled by conducting and connecting a device and a safety device with a normal conductive adhesive. It is a schematic diagram of the lithium ion secondary battery which formed the foaming electroconductive composition between the active material layer of the anode, and the electrical power collector. It is a schematic diagram of the sheet | seat produced by carrying out conductive connection of the wiring with a foaming electroconductive composition. It is the schematic diagram which showed the manufacturing method of the lithium ion battery. It is a cross-sectional photograph of the lithium ion battery electrode after a heating test. (A) is a cross-sectional TEM image of the positive electrode of Example 6 and Comparative Examples 1 and 2 after 100-cycle charge / discharge test, and (b) is the positive electrode of Example 6 and Comparative Examples 1 and 2 after 100-cycle charge / discharge test. In the EELS image of aluminum in the cross section, the bright part is the part where a large amount of aluminum element is present, and (c) is the bright part in the carbon EELS image of the cross section of the positive electrode of Example 6 and Comparative Examples 1 and 2 after the 100-cycle charge / discharge test. (D) is the portion where the bright element is present in the lithium EELS images of the cross sections of the positive electrodes of Example 6 and Comparative Examples 1 and 2 after the 100-cycle charge / discharge test. is there.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Conductive substance 2 Foamable substance 3 The space | gap formed by foaming a foamable substance 4 The external stress applied to the fracture | ruptured conductive material 5 The fracture surface contacted by the external stress 6 From the softening substance which expanded as a result of foaming Shells 7 Conductive particles 8 Insulators 9 Sites where contact between the conductive particles formed by foaming of the foamable material is prevented 10 Conductive particles 11 having a flat shape oriented by an electric field or a magnetic field or both 11 Conductive composition layer having adhesiveness and foamability 12 Device 13 Electrode, wiring 14 Substrate 15 Safety device 16 Normal conductive adhesive 17 Anode current collector 18 Active material layer 19 Cathode current collector 20 Graphite layer 21 Conductive foreign material 22 Separator 23 Insulating foam layer formed by foaming of foamable material 24 First wiring 25 Second wiring

Claims (16)

  A conductive composition comprising a foamable substance and a conductive material that foams by heat, and imparts conductivity at a temperature lower than a predetermined temperature, but is insulative by foaming the foamable substance at a temperature higher than the predetermined temperature. A conductive composition characterized in that.   The conductive composition according to claim 1, wherein the conductive composition can be solidified and has fluidity.   The conductive composition according to claim 1, wherein the foamable substance generates a flame-retardant gas.   The conductive composition according to claim 1, wherein the foamable material is coated with a softening material that softens at a predetermined temperature or higher.   The conductive composition according to claim 1, comprising a foamable substance coated with a conductive material. A conductive composition for a battery current collector coating, comprising a substance having a hydrogen bondable functional group value of 1.0 to 5.0 × 10 ⁻² mol / g and a conductive material, and capable of solidifying and having fluidity, For a battery current collector coating characterized in that the solid material excluding the conductive material after solidification contains 50% by weight or more of a substance having a hydrogen bonding functional group value of 1.0 to 5.0 × 10 ⁻² mol / g Conductive composition. 7. The substance having a hydrogen bondable functional group value of 1.0 to 5.0 × 10 ⁻² mol / g is a mixture of modified polyvinyl alcohol and polycarboxylic acid having an average degree of polymerization of 500 or more. A conductive composition for coating a battery current collector.   Furthermore, a titanium system coupling agent and / or a silane coupling agent are included as a crosslinking agent, The electrically conductive composition for battery collector coatings of Claim 6 or 7 characterized by the above-mentioned.   The conductive composition for battery current collector coating according to any one of claims 6 to 8, further comprising a foamable substance that foams by heat.   The conductive composition for battery current collector coating according to claim 9, wherein the foamable substance generates a flame-retardant gas.   The conductive composition for battery current collector coating according to claim 9 or 10, wherein the foamable material is coated with a softening material that softens at a predetermined temperature or higher.   The conductive composition for coating a battery current collector according to claim 9 or 10, comprising a foamable substance coated with a conductive material.   The conductive composition according to claim 1, comprising conductive particles having a flat shape that can be oriented by an electric field and / or a magnetic field.   A method for suppressing a mutual substitution reaction between an element constituting the battery active material and an element constituting the current collector, comprising coating the current collector with the conductive composition according to any one of claims 6 to 13.   A current collector for a battery, wherein the conductive composition according to any one of claims 6 to 13 is applied and formed on the surface of the current collector in a thickness of 50 nm to 500 nm.   An electronic device comprising the conductive composition according to claim 1.