KR101569243B1 - Electrode for electrochemical-element, and electrochemical element - Google Patents

Abstract

(assignment)
An electrode for an electrochemical device having an excellent electrode strength and an increased electrode density, and an electrochemical device capable of reducing an internal resistance and increasing an energy density and an output density.
(Solution)
An electrode composition layer comprising a conductive adhesive layer comprising a spherical graphite, carbon black and a binder for a conductive adhesive layer, and a binder for an electrode active material and an electrode composition layer, in this order from the current collector side And an electrode for an electrochemical device. The spherical graphite preferably has a volume average particle diameter of 0.1 to 50 mu m.

Description

TECHNICAL FIELD [0001] The present invention relates to an electrode and an electrochemical device for an electrochemical device,

The present invention relates to an electrode for an electrochemical device and an electrochemical device. More particularly, the present invention relates to an electrode for an electrochemical device and an electrochemical device having the electrode, which can increase the electrode density, reduce the internal resistance, and increase the energy density and power density.

Demand for electrochemical devices such as lithium ion secondary batteries, electric double layer capacitors, and lithium ion capacitors is rapidly expanding due to their small size, light weight, high energy density and repeated charge / discharge characteristics. Since the lithium ion secondary battery has a relatively large energy density, it is used in fields such as portable telephones and note-type PCs, and the electric double layer capacitor can be rapidly charged and discharged, and thus is used as a memory backup small power source for a PC or the like . The electric double layer capacitor is expected to be used as a large power source for electric vehicles. In addition, lithium ion capacitors that take advantage of the advantages of lithium ion secondary batteries and electric double layer capacitors are attracting attention because of their high energy density and high output density. These electrochemical devices are required to be further improved, such as low resistance, high capacity, and improved mechanical properties, in accordance with expansion and development of applications.

The electric double layer capacitor has polarized electrodes at the positive electrode and the negative electrode, and by using the organic electrolyte, the operating voltage can be increased and the energy density can be increased. On the other hand, however, there is a problem that the contact resistance between the current collector and the electrode composition layer is large, the electrode strength is small, and the internal resistance is large. Therefore, in order to solve these problems, various studies have been made.

For example, Patent Document 1 discloses a method in which a conductive adhesive layer containing graphite and a binder such as polyimide resin or polyamideimide resin is interposed between a roughened aluminum current collector and activated carbon, There is proposed an electrode for an electric double layer capacitor in which an electrode composition layer containing carbon black and PTFE is formed. According to Patent Document 1, the electrode strength of the electrode can be increased.

Patent Document 2 discloses a technique of forming an electrode composition layer comprising activated carbon, carbon black, and PTFE on an aluminum current collector through a conductive adhesive layer containing flake graphite, carbon black, and an SBR binder, An electrode for a bilayer capacitor has been proposed. According to Patent Document 2, the internal resistance can be lowered by the electrode.

Japanese Patent Application Laid-Open No. 9-270370 Japanese Patent Application Laid-Open No. 2005-136401 (corresponding to US Patent No. 7486497)

However, according to the study of the present inventor, it has been found that the electrode of Patent Document 1 can raise the electrode strength to some extent by using the roughened collector, but the reduction of the internal resistance is insufficient. On the other hand, in the electrode of Patent Document 2, by using two types of carbon materials as the carbon material constituting the conductive adhesive layer, it is possible to reduce the internal resistance to some extent, but it was found that the improvement of the electrode strength was insufficient.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide an electrode for an electrochemical device which is superior in electrode strength and can increase the electrode density, and an electrochemical device capable of reducing the internal resistance and increasing the energy density and output density The purpose is to provide.

Means for Solving the Problems As a result of intensive investigations to achieve the above object, the present inventors have found that, by containing spherical graphite, carbon black and a binder in the conductive adhesive layer, the electrode strength and electrode density of the obtained electrode for electrochemical devices are increased, The capacity of the electrochemical device having the electrode is improved, the internal resistance is reduced, and the energy density and the output density are improved.

The present inventors have completed the present invention based on these findings.

Thus, the present invention for solving the above problems includes the following matters as gist.

(1) An electrode composition layer comprising a conductive adhesive layer containing spherical graphite, carbon black and a binder for a conductive adhesive layer, and a binder for an electrode active material and an electrode composition layer is formed on the current collector in this order And an electrode for an electrochemical device.

(2) The electrode for electrochemical device according to (1), wherein the spherical graphite has a volume average particle diameter of 0.1 to 50 m.

(3) The electrode for an electrochemical device according to (1) or (2), wherein the weight ratio of the spheroidal graphite and the carbon black in the conductive adhesive layer is 0.05 to 1.0 in terms of a ratio of carbon black / spheroidal graphite.

(4) The electrode for an electrochemical device according to any one of (1) to (3), wherein the carbon black contains a hetero element.

(5) The electrode for an electrochemical device according to (4), wherein the content of the hetero element in the carbon black is 0.01 to 20% by weight.

(6) The electrode for an electrochemical device according to any one of (1) to (5), wherein the binder for the conductive adhesive layer is an acrylate-based polymer or a diene-based polymer.

(7) The electrode for an electrochemical device according to any one of (1) to (6), wherein the binder for the conductive adhesive layer has a polar group.

(8) The electrode for an electrochemical device according to (7), wherein the polar group is a nitrile group.

(9) The electrode for an electrochemical device according to (7), wherein the polar group is an acid group.

(10) The electrode for an electrochemical device according to (9), wherein the acid group is a carboxylic acid group.

(11) The electrode for an electrochemical device according to any one of (1) to (10), wherein the conductive adhesive layer further comprises a carboxymethyl cellulose salt.

(12) The electrode for an electrochemical device according to any one of (1) to (11), wherein the conductive adhesive layer further comprises a surfactant.

(13) The electrode for an electrochemical device according to (12), wherein the surfactant is an anionic surfactant.

(14) The electrode for electrochemical device according to any one of (1) to (13), wherein the current collector has a hole penetrating therethrough.

(15) The electrode for an electrochemical device according to any one of (1) to (14), wherein the electrode composition layer comprises composite particles comprising an electrode active material and a binder for an electrode composition layer.

(16) An electrochemical device comprising the electrode for an electrochemical device, the separator, and the electrolytic solution according to any one of (1) to (15) above.

According to the present invention, it is possible to easily produce an electrochemical device that has high electrode strength and high electrode density, low internal resistance, and high energy density and high output density. The electrochemical device of the present invention can be used as a backup power source for a memory of a PC or a portable terminal, a power source for a momentary power failure countermeasure such as a PC, an application to an electric car or a hybrid vehicle, a solar power generation energy storage system used together with a solar cell, And can be suitably used for various applications such as a combined load leveling power supply.

The electrode for an electrochemical device of the present invention comprises an electrode composition layer comprising a conductive adhesive layer comprising a spherical graphite, carbon black and a binder for a conductive adhesive layer, and a binder for an electrode active material and an electrode composition layer, In this order from the collector side.

(Conductive adhesive layer)

The conductive adhesive layer used in the present invention is provided as an adhesive layer between the current collector and the electrode composition layer and comprises a binder for spheroidal graphite, carbon black and a conductive adhesive layer.

(Spherical graphite)

The spheroidal graphite to be used in the present invention has high conductivity due to the presence of non-localized π electrons and has an aspect ratio of usually 1 to 20, preferably 1 to 10, particularly preferably 1 to 5, The graphite is spherical or roughly spherical in shape. Specific examples of spheroidal graphite include natural graphite and artificial graphite. In the present invention, when the aspect ratio of the spheroidal graphite is within the above range, the adhesion between the conductive adhesive layer and the electrode composition layer becomes high, that is, the peel strength becomes high, and as a result, the electrode strength becomes high and the electron mobility resistance can be reduced. The aspect ratio is a value represented by (short axis average diameter) / (long axis number average diameter). The minor axis average diameter and the major axis number average diameter are the number average particle diameters calculated as arithmetic average values by measuring short axis diameter and major axis diameter of 100 spherical graphite particles randomly selected by a transmission electron microscope photograph.

The volume average particle size of the spheroidal graphite used in the present invention is preferably 0.1 to 50 mu m, more preferably 0.5 to 20 mu m, particularly preferably 1 to 10 mu m. In the present invention, when spherical graphite having a volume average particle diameter in the above range is used, spherical graphite and carbon black in the conductive adhesive layer are filled with high density, so that the electron mobility resistance is reduced and the internal resistance of the electrochemical device is further reduced , The contact area between the conductive adhesive layer and the electrode composition layer increases, and the electrode strength can be further increased. Here, the volume average particle diameter is a volume average particle diameter calculated by a laser diffraction particle size distribution analyzer (SALD-3100, manufactured by Shimadzu Corporation).

In the present invention, the content of spheroidal graphite in the conductive adhesive layer is preferably 50 to 99% by mass, more preferably 60 to 95% by mass, and particularly preferably 70 to 90% by mass. In the present invention, by setting the content ratio of the spherical graphite in the conductive adhesive layer within the above range, the electron mobility resistance can be reduced and the internal resistance of the electrochemical device can be reduced.

(Carbon black)

The carbon black to be used in the present invention is an aggregate in which a graphitic carbon microcrystal is formed by aggregating several layers to form an egg-laying structure. Specifically, acetylene black, ketjen black, furnace black, channel black, thermal lamp black and the like can be mentioned. Of the carbon blacks, acetylene black, furnace black and ketjen black are particularly preferable because they can fill the conductive adhesive layer with high density and reduce the electron mobility resistance and reduce the internal resistance of the electrochemical device.

The carbon black used in the present invention preferably contains a hetero element different from the carbon element as the main component. As the hetero element, specifically, silicon, nitrogen and boron can be mentioned, and boron is particularly preferable in that the electron mobility resistance can be reduced and the internal resistance of the electrochemical device can be reduced.

The content of the hetero element in the carbon black used in the present invention is preferably in the range of 0.01 to 20 wt%, more preferably in the range of 0.05 to 10 wt%, and more preferably in the range of 0.1 to 5 wt% Is particularly preferable. When the content of the hetero element in the carbon black is within this range, the electron mobility resistance is reduced and the internal resistance of the electrochemical device is reduced.

In the present invention, the content of the carbon black in the conductive adhesive layer is preferably 1 to 50 wt%, more preferably 5 to 40 wt%, and particularly preferably 10 to 30 wt%. In the present invention, by setting the content ratio of carbon black in the conductive adhesive layer within the above range, the electron mobility resistance is reduced and the internal resistance of the electrochemical device is further reduced.

The weight ratio of the spherical graphite to the carbon black in the conductive adhesive layer is preferably 0.05 to 1, more preferably 0.1 to 0.8, and particularly preferably 0.2 to 0.5, in terms of the ratio of carbon black to spheroidal graphite. When the weight ratio of the spherical graphite and the carbon black in the conductive adhesive layer is in the above range, spheroidal graphite and carbon black in the conductive adhesive layer are filled at high density, so that the electron mobility resistance is reduced and the internal resistance of the electrochemical device is further reduced do.

The volume average particle diameter of the carbon black used in the present invention is preferably 0.01 μm or more and less than 1.0 μm, more preferably 0.05 μm or more and less than 0.8 μm, particularly preferably 0.1 μm or more and less than 0.5 μm. In the present invention, when carbon black having a volume average particle size in the above range is used, spheroidal graphite and carbon black in the conductive adhesive layer are filled with high density. The volume average particle diameter is calculated in the same manner as described above.

(Binder for conductive adhesive layer)

The binder for a conductive adhesive layer used in the present invention is not particularly limited as long as it is a compound capable of binding spherical graphite and carbon black to each other. A preferred binder is a dispersion type binder which is dispersible in a solvent. As the dispersion type binder, for example, a polymer compound such as a fluoropolymer, a diene polymer, an acrylate polymer, a polyimide, a polyamide, and a polyurethane polymer may be used, and a fluoropolymer, a diene polymer or an acrylate polymer is preferable, A diene polymer or an acrylate polymer is more preferable because it can increase a withstanding voltage and can increase an energy density of an electrochemical device.

The diene polymer is a copolymer obtained by polymerizing a homopolymer of a conjugated diene or a monomer mixture containing a conjugated diene, or a hydrogenated product thereof. The proportion of the conjugated diene in the monomer mixture is usually 30% by weight or more, preferably 40% by weight or more, and more preferably 50% by weight or more. Specific examples of the diene-based polymer include conjugated diene homopolymers such as polybutadiene and polyisoprene; Aromatic vinyl-conjugated diene copolymers such as styrene-butadiene copolymer (SBR) which may be carboxy-modified; Copolymers of aromatic vinyl-conjugated diene-carboxylic acid group-containing monomers such as styrene-butadiene-methacrylic acid copolymer and styrene-butadiene-itaconic acid copolymer; Vinyl cyanide-conjugated diene copolymers such as acrylonitrile-butadiene copolymer (NBR); Hydrogenated SBR, and hydrogenated NBR.

Acrylate polymer comprises a monomer unit derived from a compound represented by the general formula (1): CH ₂ ═CR ¹ -COOR ² (wherein R ¹ represents a hydrogen atom or a methyl group, and R ² represents an alkyl group or a cycloalkyl group) ≪ / RTI > Specific examples of the compound represented by the general formula (1) include ethyl acrylate, propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, n-amyl acrylate, Acrylate such as hexyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, nonyl acrylate, lauryl acrylate, and stearyl acrylate; Propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-amyl methacrylate, Methacrylates such as n-hexyl acrylate, 2-ethylhexyl methacrylate, octyl methacrylate, isodecyl methacrylate, lauryl methacrylate, tridecyl methacrylate, and stearyl methacrylate. have. Of these, acrylate is preferable, and n-butyl acrylate and 2-ethylhexyl acrylate are particularly preferable in that the strength of the obtained electrode can be improved. The proportion of the monomer unit derived from the compound represented by the general formula (1) in the acrylate polymer is usually 50% by weight or more, preferably 70% by weight or more. When the acrylate polymer having the above-mentioned ratio of the monomer units derived from the compound represented by the general formula (1) is used, the heat resistance is high and the internal resistance of the resulting electrode for an electrochemical device can be reduced.

The binder for a conductive adhesive layer used in the present invention preferably has a polar group. When the binder for a conductive adhesive layer has a polar group, bondability between the collector and the electrode composition layer can be further enhanced. In the present invention, the polar group refers to a functional group having a functional group or a polar group which can be dissociated in water. Specific examples thereof include an acid group, a nitrile group, an amide group, an amino group, a hydroxyl group and an epoxy group. Of these, an acid group, a nitrile group, and an epoxy group are preferable, and an acid group or a nitrile group is more preferable because a withstanding voltage can be increased. In the present invention, the binder for a conductive adhesive layer to be used may have one kind of polar group, and preferably has two or more kinds. The binder for a conductive adhesive layer has two or more kinds of polar groups, so that the bondability between the current collector and the electrode composition layer can be further enhanced. Specific examples of the combination of two polar groups include an acid group, a nitrile group, an acid group and an amide group, an acid group and an amino group. When three or more types of polar groups are used, combinations of three polar groups may be used. The polar group in the binder may be introduced into the polymer, for example, by using a monomer having a polar group or by using a polymerization initiator having a polar group when polymerizing a polymer constituting the binder for a conductive adhesive layer.

The content of the polar group in the binder for conductive adhesive layer is preferably 0.1 to 40% by weight, more preferably 0.5 to 30% by weight, particularly preferably 1 to 20% by weight, based on the content of the monomer having a polar group . When the content of the polar group in the binder for conductive adhesive layer is within the above range, the binding property to the current collector is excellent and the electrode strength of the electrode can be increased.

Examples of the monomer containing a nitrile group as a polar group include acrylonitrile and methacrylonitrile, and acrylonitrile is preferable in that a withstanding voltage can be increased.

Monomers containing an acid group as a polar group include monomers having a carboxylic acid group such as monobasic acid-containing monomers such as acrylic acid and methacrylic acid, and dibasic acid-containing monomers such as maleic acid, fumaric acid and itaconic acid; Monomers having sulfonic acid groups such as styrenesulfonic acid and methallylsulfonic acid, and the like. Among them, monomers having carboxylic acid groups are preferable, and dibasic acid-containing monomers are particularly preferable in that the withstand voltage can be increased.

The shape of the binder for a conductive adhesive layer used in the electrode for an electrochemical device of the present invention is not particularly limited and may be suitably selected depending on the formability of the electrode and the charge / Since the deterioration can be suppressed, it is preferable to be in a particulate form. Examples of the particulate binder include those in which particles of a binder such as latex are dispersed in water, and those in powder form obtained by drying such a dispersion.

The glass transition temperature (Tg) of the binder for a conductive adhesive layer used in the present invention is preferably 50 占 폚 or lower, more preferably -40 占 폚 to 0 占 폚. When the glass transition temperature (Tg) of the binder for a conductive adhesive layer is within this range, the binder is excellent in a small amount of use and has excellent bondability between the current collector and the electrode composition layer, has a strong electrode strength, , The electrode density can be easily increased by a pressing process at the time of forming the electrode.

The number average particle diameter of the binder for a conductive adhesive layer used in the present invention in particulate form is not particularly limited and is usually 0.0001 to 100 mu m, preferably 0.001 to 10 mu m, more preferably 0.01 to 10 mu m, 1 占 퐉. When the number average particle diameter of the binder for the conductive adhesive layer in the particulate form is within this range, an excellent binding force can be provided to the conductive adhesive layer and the electrode composition layer even by using a small amount. Here, the number average particle size is the number average particle size calculated as the arithmetic mean value by measuring the diameter of 100 randomly selected binder particles by a transmission electron microscope photograph. The shape of the particle may be either spherical or irregular. These binders may be used alone or in combination of two or more.

In the present invention, the content of the binder for a conductive adhesive layer in the conductive adhesive layer is usually 0.1 to 50 parts by weight, preferably 0.5 to 20 parts by weight, more preferably 1 To 10 parts by weight. When the amount of the binder for a conductive adhesive layer in the conductive adhesive layer is within this range, the adhesiveness between the resulting electrode composition layer and the current collector can be sufficiently ensured, the capacity of the electrochemical device can be increased, and the internal resistance can be lowered .

(Other components)

The conductive adhesive layer used in the present invention includes spherical graphite, carbon black and a binder for the conductive adhesive layer as essential components, and further preferably contains a carboxymethyl cellulose salt and / or a surfactant.

The carboxymethylcellulose salt preferably used in the present invention is a dispersant for forming a conductive adhesive layer and specifically includes carboxymethylcellulose acid, carboxymethylcellulose ammonium salt, carboxymethylcellulose alkali metal salt, carboxymethylcellulose alkaline earth metal salt, etc. . Among them, carboxymethylcellulose ammonium salt and carboxymethylcellulose alkali metal salt are preferable, and carboxymethylcellulose ammonium salt is particularly preferable. Particularly, when carboxymethylcellulose ammonium salt is used, spheroidal graphite, carbon black and a binder can be uniformly dispersed, the degree of filling of the conductive adhesive layer can be increased, and the electron mobility resistance can be reduced.

The content of the carboxymethylcellulose salt in the conductive adhesive layer can be used within a range that does not impair the effect of the present invention and is not particularly limited and is preferably 0.1 to 20 parts by weight based on 100 parts by weight of the spherical graphite, Preferably 0.5 to 15 parts by weight, particularly preferably 0.8 to 10 parts by weight. When the content of the carboxymethylcellulose salt in the conductive adhesive layer is within this range, the durability of the obtained electrochemical device can be further improved.

(Surfactants)

The surfactant preferably used in the present invention is to uniformly disperse spheroidal graphite, carbon black and a binder to lower the surface tension of the current collector. Specifically, the surfactant includes an alkylsulfuric acid ester salt, an alkylbenzenesulfonic acid salt, a fat Anionic surfactants such as acid salts and naphthalenesulfonic acid formalin condensates; Nonionic surfactants such as polyoxyethylene alkyl ethers and glycerin fatty acid esters; Cationic surfactants such as alkylamine salts and quaternary ammonium salts; Amphoteric surfactants such as alkyl amine oxides and alkyl betaines. Among these, anionic surfactants and nonionic surfactants are preferable, and anionic surfactants are particularly preferable because of excellent durability of electrochemical devices.

The content of the surfactant in the conductive adhesive layer is preferably 0.5 to 20 parts by weight, more preferably 1.0 to 15 parts by weight, particularly preferably 2.0 to 10 parts by weight, based on 100 parts by weight of the spherical graphite . When the content of the surfactant in the conductive adhesive layer is within this range, the durability of the electrochemical device is excellent.

The conductive adhesive layer used in the present invention can be obtained by mixing a conductive adhesive composition obtained by mixing and kneading spherical graphite, carbon black and a binder, and if necessary, a carboxymethyl cellulose salt or a surfactant in a solvent (dispersion medium) On a current collector, and dried. The solvent is not particularly limited, but water is preferable in view of environmental friendliness and drying facility.

Specific examples of the apparatus used for obtaining the conductive adhesive composition used in the present invention include a ball mill, a sand mill, a pigment disperser, a brain ball, an ultrasonic disperser, a homogenizer, a planetary mixer, a Hobart mixer, have.

The method of forming the conductive adhesive layer used in the present invention is not particularly limited. For example, the conductive adhesive composition is formed on the current collector by a doctor blade method, a dipping method, a reverse roll method, a direct roll method, a gravure method, an extrusion method, a brush coating method or the like.

The solid content of the conductive adhesive composition used in the present invention varies depending on the coating method, and is usually 10 to 60% by weight, preferably 15 to 50% by weight, and particularly preferably 20 to 40% by weight. When the solid content concentration is within this range, the resulting conductive adhesive layer is called up, and the energy density and power density of the electrochemical device are increased.

The viscosity of the conductive adhesive composition used in the present invention varies depending on the coating method, and is usually 50 to 10,000 mPa · s, preferably 100 to 5,000 mPa · s, and particularly preferably 200 to 2,000 mPa · s. When the viscosity of the conductive adhesive composition is within this range, a uniform conductive adhesive layer can be formed on the current collector.

Examples of the drying method of the conductive adhesive layer include drying by hot air, hot air, low-humidity air, vacuum drying, and irradiation by irradiation with (infrared) or electron beams. Among them, a hot air drying method and a far infrared ray drying method are preferable. The drying temperature and the drying time are preferably a temperature and a time at which the solvent in the slurry-like conductive adhesive composition applied to the current collector can be completely removed. Specifically, the drying temperature is usually 50 to 300 占 폚, preferably 80 to 250 占 폚 to be. The drying time is usually 2 hours or less, preferably 5 seconds to 30 minutes.

The surface roughness Ra of the conductive adhesive layer used in the present invention is preferably 0.15 占 퐉 or more, more preferably 0.3 占 퐉 or more, and particularly preferably 0.5 占 퐉 or more. When the surface roughness of the conductive adhesive layer is within this range, the adhesiveness between the conductive adhesive layer and the electrode composition layer is improved, the electrode strength is increased, and the internal resistance can be reduced. Here, the surface roughness Ra of the conductive adhesive layer is calculated from the equation shown in the following equation by using a nano-scale hybrid microscope (VN-8010, manufactured by KYENS), for example, in accordance with JIS B0601 . In the following equation, L is the measurement length, and x is the deviation from the average line to the measurement curve. The upper limit of the surface roughness of the conductive adhesive layer is the thickness of the conductive adhesive layer.

The thickness of the conductive adhesive layer used in the present invention is usually 0.01 to 20 占 퐉, preferably 0.1 to 15 占 퐉, and particularly preferably 1 to 10 占 퐉. When the thickness of the conductive adhesive layer is in the above range, good adhesion can be obtained and electron migration resistance can be reduced.

(Whole house)

As the material of the current collector used in the present invention, for example, metal, carbon, conductive polymer or the like can be used, and a metal is preferably used. As the metal for the current collector, aluminum, platinum, nickel, tantalum, titanium, stainless steel, copper, and other alloys are usually used. Of these, copper, aluminum or an aluminum alloy is preferably used in terms of conductivity and withstand voltage.

The shape of the current collector used in the present invention may be a current collector such as a metal foil or a metal edge bead; (Hereinafter sometimes referred to as a " mesh current collector ") having a through hole such as expanded metal, punching metal, or mesh can be exemplified. In addition, the diffusion resistance of the electrolyte ion can be reduced, From the viewpoint that the output density can be improved, a current collector having a through hole is preferable, and an expanded metal or a punching metal is particularly preferable from the viewpoint of excellent electrode strength.

The ratio (aperture ratio) of the through holes of the mesh current collector preferably used in the present invention is 10 to 80% by area, preferably 20 to 60% by area, more preferably 30 to 50% by area. When the ratio of the through holes is within this range, the diffusion resistance of the electrolytic solution is reduced and the internal resistance of the electrochemical device is reduced.

The thickness of the collector used in the present invention is usually 5 to 100 mu m, preferably 10 to 70 mu m, particularly preferably 20 to 50 mu m.

The electrode composition layer used in the present invention comprises an electrode active material and a binder for the electrode composition layer.

(Electrode active material)

The electrode active material used in the present invention is a substance that transports electrons in an electrode for an electrochemical device. The electrode active material mainly includes an active material for a lithium ion secondary battery, an active material for an electric double layer capacitor, and an active material for a lithium ion capacitor.

Active materials for the lithium ion secondary battery include positive and negative electrodes. Specific examples of the electrode active material used for the positive electrode of the electrode for a lithium ion secondary battery include lithium-containing composite metal oxides such as LiCoO ₂ , LiNiO ₂ , LiMnO ₂ , LiMn ₂ O ₄ , LiFePO ₄ and LiFeVO ₄ ; Transition metal sulfides such as TiS ₂ , TiS ₃ and amorphous MoS ₃ ; Cu ₂ V ₂ O ₃ , amorphous V ₂ O · P ₂ O ₅ , MoO ₃ , V ₂ O ₅ and V ₆ O ₁₃ . Further, conductive polymers such as polyacetylene and poly-p-phenylene can be mentioned. Preferably, it is a lithium-containing composite metal oxide.

Specific examples of the electrode active material used for the negative electrode of the electrode for a lithium ion secondary battery include a carbonaceous material such as amorphous carbon, graphite, natural graphite, mesocarbon microbead (MCMB), and pitch-based carbon fiber; And conductive polymers such as polyacene. Preferably, it is a crystalline carbonaceous material such as graphite, natural graphite, mesocarbon microbead (MCMB), and the like.

The shape of the electrode active material used for the electrode for a lithium ion secondary battery is preferably set in a granular form. When the shape of the particles is spherical, a higher density electrode can be formed at the time of electrode formation.

The volume average particle size of the electrode active material used in the electrode for a lithium ion secondary battery is usually 0.1 to 100 占 퐉, preferably 1 to 50 占 퐉, more preferably 5 to 20 占 퐉 in both the positive electrode and the negative electrode.

The tap density of the electrode active material used for the electrode for the lithium ion secondary battery is not particularly limited, but is preferably 2 g / cm 3 or more for the positive electrode and 0.6 g / cm 3 or more for the negative electrode.

As the electrode active material used in the electrode for the electric double layer capacitor, generally, a carbon isotope is used. Specific examples of carbon isotopes include activated carbon, polyacene, carbon whisker and graphite, and powders or fibers thereof can be used. Preferred examples of the electrode active material include activated carbon, and specifically, activated carbon made from phenol resin, rayon, acrylonitrile resin, pitch, palm kernel, and the like.

The volume average particle diameter of the electrode active material used in the electrode for electric double layer capacitor is usually 0.1 to 100 占 퐉, preferably 1 to 50 占 퐉, more preferably 5 to 20 占 퐉.

The specific surface area of the electrode active material used for the electrode for electric double layer capacitor is preferably 30 m2 / g or more, more preferably 500 to 5,000 m2 / g, and further preferably 1,000 to 3,000 m2 / g. As the specific surface area of the electrode active material is larger, the density of the obtained electrode composition layer tends to decrease. Therefore, by appropriately selecting the electrode active material, an electrode composition layer having a desired density can be obtained.

Electrode active materials used for electrodes for lithium ion capacitors include positive electrodes and negative electrodes. The electrode active material used for the positive electrode of the lithium ion capacitor electrode may be one that can carry lithium ions and anion such as tetrafluoroborate reversibly. Concretely, generally, carbon isotopes are used, and electrode active materials used in electric double layer capacitors can be widely used. When carbon isotopes are used in combination, two or more carbon isotopes of different average particle diameter or particle size distribution may be used in combination. As the heat-treated product of the aromatic condensation polymer, a polyacene-based organic semiconductor (PAS) having a polyacene skeleton structure having an atomic ratio of hydrogen atoms / carbon atoms of 0.50 to 0.05 can also be preferably used. Preferably, it is an electrode active material used for an electrode for an electric double layer capacitor.

The electrode active material used for the negative electrode of the lithium ion capacitor electrode is a material capable of reversibly carrying lithium ions. Specifically, an electrode active material used in a negative electrode of a lithium ion secondary battery can be widely used. Preferable examples include crystalline carbon materials such as graphite and non-graphitized carbon, and polyacene-based materials (PAS) also described as the positive electrode active material. These carbon materials and PAS are obtained by carbonizing a phenol resin or the like, reviving it if necessary, and then pulverizing it.

It is preferable that the shape of the electrode active material used for the electrode for the lithium ion capacitor is set in a granular form. When the shape of the particles is spherical, a higher density electrode can be formed at the time of electrode formation.

The volume average particle size of the electrode active material used in the electrode for the lithium ion capacitor is usually 0.1 to 100 占 퐉, preferably 1 to 50 占 퐉, more preferably 5 to 20 占 퐉 in both the positive electrode and the negative electrode. These electrode active materials may be used alone or in combination of two or more.

(Binder for electrode composition layer)

The binding agent (binder for electrode composition layer) used in the electrode composition layer is not particularly limited as long as it is a compound capable of binding an electrode active material or a conductive agent described below. A preferred binder is a dispersion type binder which is dispersible in a solvent. Examples of the dispersion type binder include a polymer compound such as a fluoropolymer, a diene polymer, an acrylate polymer, a polyimide polymer, a polyamide polymer, and a polyurethane polymer, and a fluoropolymer, a diene polymer or an acrylate polymer , And a diene polymer or an acrylate polymer is more preferable in that the withstand voltage can be increased and the energy density of the electrochemical device can be increased.

The diene polymer is a copolymer obtained by polymerizing a homopolymer of a conjugated diene or a monomer mixture containing a conjugated diene, or a hydrogenated product thereof. The proportion of the conjugated diene in the monomer mixture is usually 30% by weight or more, preferably 40% by weight or more, and more preferably 50% by weight or more. Examples of the conjugated dienes include butadiene and isoprene. Specific examples of the diene-based polymer include conjugated diene homopolymers such as polybutadiene and polyisoprene; Aromatic vinyl-conjugated diene copolymers such as styrene-butadiene copolymer (SBR) which may be carboxy-modified; Copolymers of aromatic vinyl-conjugated diene-carboxylic acid group-containing monomers such as styrene-butadiene-methacrylic acid copolymer and styrene-butadiene-itaconic acid copolymer; Vinyl cyanide-conjugated diene copolymers such as acrylonitrile-butadiene copolymer (NBR); Hydrogenated SBR, and hydrogenated NBR.

Acrylate polymer comprises a monomer unit derived from a compound represented by the general formula (1): CH ₂ ═CR ¹ -COOR ² (wherein R ¹ represents a hydrogen atom or a methyl group, and R ² represents an alkyl group or a cycloalkyl group) ≪ / RTI > Specific examples of the compound represented by the general formula (1) include ethyl acrylate, propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, n-amyl acrylate, Acrylate such as hexyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, nonyl acrylate, lauryl acrylate, and stearyl acrylate; Propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-amyl methacrylate, Methacrylates such as n-hexyl acrylate, 2-ethylhexyl methacrylate, octyl methacrylate, isodecyl methacrylate, lauryl methacrylate, tridecyl methacrylate, and stearyl methacrylate. have. Of these, acrylate is preferable, and n-butyl acrylate and 2-ethylhexyl acrylate are particularly preferable in that the strength of the obtained electrode can be improved. The proportion of the monomer unit derived from the compound represented by the general formula (1) in the acrylate-based polymer is usually 50% by weight or more, preferably 70% by weight or more. When the acrylate polymer having the above-mentioned ratio of the monomer units derived from the compound represented by the general formula (1) is used, the heat resistance is high and the internal resistance of the resulting electrode for an electrochemical device can be further reduced.

As the acrylate polymer, besides the compound represented by the general formula (1), a copolymerizable carboxylic acid group-containing monomer can be used, and specific examples include monobasic acid-containing monomers such as acrylic acid and methacrylic acid; And dibasic acid-containing monomers such as maleic acid, fumaric acid and itaconic acid. Among them, dibasic acid-containing monomers are preferable, itaconic acid is particularly preferable because it can improve the binding property with the current collector and improve the electrode strength. These monobasic acid-containing monomers and dibasic acid-containing monomers may be used either individually or in combination of two or more. The amount of the carboxylic acid group-containing monomer at the time of copolymerization is usually 0.1 to 50 parts by weight, preferably 0.5 to 20 parts by weight, more preferably 1 to 10 parts by weight, based on 100 parts by weight of the compound represented by formula (1) It is the extent of wealth. When the amount of the carboxylic acid group-containing monomer is within this range, the bondability with the conductive adhesive layer is excellent and the strength of the obtained electrode is improved.

As the acrylate polymer, in addition to the compound represented by the general formula (1), a copolymerizable nitrile group-containing monomer can be used. Specific examples of the nitrile group-containing monomer include acrylonitrile and methacrylonitrile. Among them, acrylonitrile is preferred because it can improve the binding property with the current collector and improve the electrode strength Do. The amount of acrylonitrile is usually in the range of 0.1 to 40 parts by weight, preferably 0.5 to 30 parts by weight, more preferably 1 to 20 parts by weight, based on 100 parts by weight of the compound represented by formula (1). When the amount of the acrylonitrile is within this range, bondability with the conductive adhesive layer is excellent and the strength of the resulting electrode is improved.

The shape of the binder for the electrode composition layer used in the electrode for an electrochemical device of the present invention is not particularly limited, but is preferably in the range of from 0.1 to 10 parts by weight, It is preferable to be in a particulate form. Examples of the particulate binder include those in which particles of a binder such as latex are dispersed in water, and those in powder form obtained by drying such a dispersion.

The glass transition temperature (Tg) of the binder for the electrode composition layer used in the present invention is preferably 50 占 폚 or lower, more preferably -40 占 폚 to 0 占 폚. When the glass transition temperature (Tg) of the binder composition for the electrode composition layer is within this range, the binder is excellent in a small amount of use, has excellent bondability with the conductive adhesive layer, has strong electrode strength, The electrode density can be easily increased by the pressing process at the time of formation.

The polymer constituting the binder for the electrode composition layer may contain a structural unit derived from a monomer having a crosslinkable group. By introducing a crosslinkable group into the binder, curing properties are imparted to the binder and the crosslinking density of the binder can be increased. By increasing the crosslinking density, the swelling property of the binder to the electrolytic solution can be lowered, and the lifetime characteristics of the resulting electrochemical device can be improved. As the structural unit of the monomer having a crosslinkable group, there may be mentioned a structural unit of allyl acrylate or a structural unit of allyl methacrylate.

The amount of the binder for the electrode composition layer in the electrode composition layer is usually in the range of 0.1 to 50 parts by weight, preferably 0.5 to 20 parts by weight, more preferably 1 to 10 parts by weight, based on 100 parts by weight of the electrode active material . When the amount of the binder in the electrode composition layer is within this range, the adhesion between the obtained electrode composition layer and the conductive adhesive layer can be sufficiently secured, and the capacity of the electrochemical device can be increased and the internal resistance can be lowered.

(Other components)

The electrode composition layer used in the present invention includes an electrode active material and a binder for an electrode composition layer as essential components, but may contain other components. Other components include conductive agents and dispersants.

(Conductive agent)

The conductive agent used in the present invention is a conductive agent having particles of carbon having no pores capable of forming an electric double layer. Specific examples include conductive carbon blacks such as furnace black, acetylene black, and Ketjen black (registered trademark of Akzo Nobel Chemicals, Bethroten Peninsula). Of these, acetylene black and furnace black are preferred.

The volume average particle diameter of the conductive agent used in the present invention is preferably smaller than the volume average particle diameter of the electrode active material, and the range is usually 0.001 to 10 mu m, preferably 0.05 to 5 mu m, more preferably 0.01 to 1 mu m to be. When the volume average particle diameter of the conductive agent is in this range, high conductivity can be obtained with a smaller amount of use. These conductive agents may be used alone or in combination of two or more. The amount of the conductive agent in the electrode composition layer is usually in the range of 0.1 to 50 parts by weight, preferably 0.5 to 15 parts by weight, more preferably 1 to 10 parts by weight, based on 100 parts by weight of the electrode active material. When the amount of the conductive agent is in this range, the capacitance of the obtained electrochemical device using the electrode for an electrochemical device can be increased and the internal resistance can be lowered.

(Dispersant)

Specific examples of the dispersing agent include cellulosic polymers such as carboxymethylcellulose, methylcellulose, ethylcellulose and hydroxypropylcellulose, and ammonium salts or alkali metal salts thereof; Poly (meth) acrylates such as poly (meth) acrylate; Polyvinyl alcohol, modified polyvinyl alcohol, polyethylene oxide; Polyvinyl pyrrolidone, polycarboxylic acid, starch oxide, starch phosphate, casein, various modified starches, chitin, and chitosan derivatives. These dispersants may be used alone or in combination of two or more. Among them, a cellulose-based polymer is preferable, and carboxymethylcellulose or an ammonium salt or an alkali metal salt thereof is particularly preferable.

The amount of the dispersing agent in the electrode composition layer can be used within a range that does not impair the effect of the present invention and is not particularly limited and is usually 0.1 to 10 parts by weight, 5 parts by weight, and more preferably 0.8 to 2 parts by weight.

(Electrode composition layer)

The electrode composition layer used in the present invention can be produced by using an electrode composition obtained by mixing a binder for an electrode active material and an electrode composition layer as an essential component and a conductive agent or a dispersing agent added as required, But the formation method thereof is not limited. Specifically, the electrode composition is prepared by 1) kneading an electrode active material and a binder for an electrode composition layer, and optionally a conductive agent or a dispersant to be added, and subjecting the obtained sheet-like electrode composition to surface treatment with a conductive adhesive layer (2) a paste-like electrode composition comprising an electrode active material and a binder for an electrode composition layer, and optionally a conductive agent and a dispersant to be added, is prepared, and a conductive adhesive layer (Wet forming method), and 3) a binder for electrode active material and electrode composition layer, and optionally a conductive agent or a dispersant to be added, is prepared, and this is coated on a surface On a current collector having a conductive adhesive layer, and if necessary, roll-pressing May be those (dry molding). Among them, 2) wet forming method, 3) dry forming method are preferred, and 3) electrochemical device capable of obtaining a dry forming method can be increased in capacity and internal resistance can be reduced.

(Composite particle)

In the case of forming the electrode composition layer by the above-mentioned dry forming method, it is preferable that the electrode composition is a composite particle comprising an electrode active material and a binder. When the electrode composition is a composite particle, the electrode strength of the obtained electrode for an electrochemical device can be increased and the internal resistance can be reduced. The composite particles referred to in the present invention refer to particles in which a plurality of materials are integrated, such as electrode active materials, binders, and other materials that may be contained in accordance with necessity such as a conductive agent and a dispersant.

The composite particles preferably used in the present invention are produced by granulating using an electrode active material, a binder, and other components added as needed such as a conductive agent and a dispersant.

The method of assembling the composite particles is not particularly limited and may be selected from the group consisting of spray drying and granulation, electroless layer assembly, compression assembly, agitation assembly, extrusion assembly, crushing assembly, fluidized bed assembly, fluidized bed multifunctional assembly, , And the like. Among them, the spray-drying granulation method is preferable because composite particles in which the binder and the conductive agent are distributed are easily obtained near the surface. By using the composite particles obtained by the spray drying and granulation method, the electrode of the present invention can be obtained with high productivity. Further, the internal resistance of the electrode can be further reduced.

In the spray-drying granulation method, the electrode active material and the binder, and optional components such as the conductive agent and the dispersant are dispersed or dissolved in the solvent to form an electrode active material and a binder, and a conductive agent, a dispersant, Thereby obtaining a slurry in which optional components are dispersed or dissolved.

The solvent used for obtaining the slurry is not particularly limited, but when the above-mentioned dispersant is used, a solvent capable of dissolving the dispersant is preferably used. Concretely, usually water is used. An organic solvent may be used, or a mixed solvent of water and an organic solvent may be used. Examples of the organic solvent include alkyl alcohols such as methyl alcohol, ethyl alcohol and propyl alcohol; Alkyl ketones such as acetone and methyl ethyl ketone; Ethers such as tetrahydrofuran, dioxane and diglyme; Amides such as diethylformamide, dimethylacetamide, N-methyl-2-pyrrolidone, and dimethylimidazolidinone; Sulfur-based solvents such as dimethylsulfoxide and sulfolane; And the like. Of these, alcohols are preferable as organic solvents. When water and an organic solvent having a boiling point lower than water are used in combination, the drying speed can be increased at the time of spray drying. Further, the dispersibility of the binder or the solubility of the dispersing agent varies depending on the amount or type of the organic solvent used in combination with water. As a result, the viscosity and fluidity of the slurry can be adjusted and the production efficiency can be improved.

The amount of the solvent used when preparing the slurry is such that the solid content of the slurry is usually in the range of 1 to 50 mass%, preferably 5 to 50 mass%, and more preferably 10 to 30 mass%. When the solid content concentration is in this range, it is preferable that the binder is uniformly dispersed.

The method or order of dispersing or dissolving optional components such as an electrode active material and a binder, an optional component such as a conductive agent, a dispersant, and other additives in a solvent is not particularly limited, and for example, an electrode active material, a conductive agent, A dispersing agent and the like are added and mixed; A method of dissolving a dispersant in a solvent, adding a binder for an electrode composition layer (for example, an aqueous dispersion of polymer particles) dispersed in a solvent, and finally adding and mixing an electrode active material and a conductive agent; A method in which an electrode active material and a conductive agent are added to and mixed with a binder for an electrode composition layer dispersed in a solvent, and a dispersant dissolved in a solvent is added to the mixture, followed by mixing. Examples of the mixing means include a mixing device such as a ball mill, a sand mill, a bead mill, a pigment disperser, a brain ball, an ultrasonic disperser, a homogenizer, a homomixer, and a planetary mixer. The mixing is usually carried out at room temperature to 80 캜 for 10 minutes to several hours.

The viscosity of the slurry is usually in the range of 10 to 3,000 mPa · s, preferably 30 to 1,500 mPa · s, more preferably 50 to 1,000 mPa · s at room temperature. When the viscosity of the slurry is in this range, the productivity of the composite particles can be increased. Further, the higher the viscosity of the slurry, the larger the spray droplet and the larger the weight average particle diameter of the resulting composite particles.

Next, the slurry obtained above is spray dried and granulated to obtain composite particles. Spray drying is carried out by spraying the slurry in hot air and drying. As an apparatus used for spraying the slurry, an atomizer can be mentioned. Atomizer has two types of devices, a rotary disc type and a pressure type. In the rotary disk method, a slurry is introduced into a substantially central portion of a disk rotating at a high speed, and the slurry is discharged out of the disk by the centrifugal force of the disk, and the slurry is then misted. The rotation speed of the disc depends on the size of the disc, and is usually 5,000 to 40,000 rpm, preferably 15,000 to 40,000 rpm. The lower the rotational speed of the disk, the larger the spray droplet and the larger the weight average particle diameter of the resulting composite particles. As the rotator disk type atomizer, there are a pin type and a vane type, preferably a pin type atomizer. The fin type atomizer is composed of a single centrifugal atomizing apparatus using a spray booth and a plurality of atomizing rollers mounted thereon so as to be freely attached and detached between the upper and lower mounting disks on a substantially concentric circle along the periphery thereof have. The slurry is introduced from the center of the spray, attached to the spray roller by centrifugal force, moved outwardly of the roller surface, and finally sprayed away from the roller surface. On the other hand, the pressurizing method is a method in which the slurry is pressurized and dried by mist from the nozzle.

The temperature of the slurry to be sprayed is usually room temperature, but it may be heated to room temperature or higher. The temperature of the hot air at spray drying is usually 80 to 250 占 폚, preferably 100 to 200 占 폚. In spray drying, a method of blowing hot air is not particularly limited. For example, there are a method in which hot air and spray direction are cocurrent in the horizontal direction, a method in which the hot air is sprayed and dropped together with hot air, A method of countercurrent contact, a method in which a sprayed water droplet is cocurrent with the first hot air, and then gravitationally falls and then makes a countercurrent contact.

The composite particles obtained by the above production method may be post-treated after the production of the particles, if necessary. As specific examples, the particle surface may be modified by mixing the composite particle with the electrode active material, the conductive agent, the binder for the electrode composition layer, the dispersant, or other additives to improve or reduce the fluidity of the composite particles, To improve the electrical conductivity of the composite particles, to adjust the average charge amount of the composite particles, and the like.

In order to adjust the average charge amount of the composite particles, a charge control agent may be used. Specific examples include silicon dioxide particles, styrene-methacrylic acid ester copolymer particles, nigrosine dyes, triphenylmethane dyes, quaternary ammonium salts, resins containing quaternary ammonium groups and / or amino groups, and the like.

The shape of the composite particles preferably used in the present invention is preferably substantially spherical. That is, assuming that the minor axis diameter of the composite particle is L _s and the major axis diameter is L ₁ and L _a = (L _s + L ₁ ) / 2, the value of (1- (L ₁ -L _s ) / L _a ) × 100 Is a sphericity (%), the sphericity is preferably 80% or more, and more preferably 90% or more. Here, the short axis diameter L _s and the long axis diameter L ₁ are average values for 100 arbitrary composite particles measured from a transmission electron microscopic image. The larger this value is, the closer the composite particle is to the true sphere.

The volume average particle size of the composite particles preferably used in the present invention is usually in the range of 10 to 100 占 퐉, preferably 20 to 80 占 퐉, more preferably 30 to 60 占 퐉. The volume average particle diameter can be measured using a laser diffraction particle size distribution measuring apparatus.

In the present invention, the feeder used in the process of supplying the composite particles is not particularly limited, but it is preferable that the feeder is a quantitative feeder capable of quantitatively supplying the composite particles. Here, the quantitative supply means that the composite particles are continuously supplied using such a feeder, the supply amount is measured a plurality of times at constant intervals, and the CV value (=? M / m x 100) is 4 or less. The quantitative feeder preferably used in the present invention has a CV value of preferably 2 or less. Specific examples of the metering feeder include a gravity feeder such as a table feeder and a rotary feeder, a mechanical feeder such as a screw feeder and a belt feeder, and the like. Among them, a rotary feeder is preferable.

Subsequently, the current collector and the supplied composite particles are pressed with a pair of rolls to form an electrode composition layer on the current collector having the conductive adhesive layer. In this step, the heated composite particles are molded into a sheet-like electrode composition layer with a pair of rolls, if necessary. The temperature of the supplied composite particles is preferably 40 to 160 캜, more preferably 70 to 140 캜. When the composite particles in this temperature range are used, there is no slippage of the composite particles on the surface of the press roll, and the composite particles are continuously and uniformly supplied to the press roll, so that the film thickness is uniform, A small, electrode composition layer can be obtained.

The temperature at the time of molding is usually 0 to 200 캜, preferably higher than the melting point or the glass transition temperature of the binder, and more preferably 20 캜 or more higher than the melting point or the glass transition temperature. The forming speed in the case of using a roll is usually more than 0.1 m / min, preferably 35 to 70 m / min. The press line pressure between press rolls is usually 0.2 to 30 kN / cm, preferably 0.5 to 10 kN / cm.

In the above production method, the arrangement of the pair of rolls is not particularly limited, but is preferably arranged substantially horizontally or substantially vertically. In the case where the current collector is disposed substantially horizontally, the current collector having the conductive adhesive layer is continuously supplied between the pair of rolls, and the composite particles are supplied to at least one of the rolls, And the electrode composition layer can be formed by pressurization. In the case of vertically arranging the conductive particles, the current collector having the conductive adhesive layer is transported in the horizontal direction, the composite particles are supplied onto the current collector having the conductive adhesive layer, and the supplied composite particles are dispersed The current collector is supplied between the pair of rolls, and the electrode composition layer can be formed by pressurization.

In order to eliminate variations in the thickness of the formed electrode composition layer and increase the density and increase the capacity, further post-pressurization may be carried out if necessary. In the post-pressurizing method, a pressing process by a roll is generally used. In the roll press process, two circumferential rolls are arranged vertically in parallel at narrow intervals, and the rolls are rotated in opposite directions to press the electrodes therebetween. The temperature of the roll may be adjusted by heating or cooling.

In the case where the electrode composition layer is formed by a wet molding method, a paste-like electrode composition comprising an electrode active material and a binder for an electrode composition layer, and a conductive agent and a dispersant to be added as required is prepared, , And further drying or heating, if necessary, may be carried out. The application method is not particularly limited. For example, methods such as a doctor blade method, a dipping method, a reverse roll method, a direct roll method, a gravure method, an extrusion method, and a brush coating method can be used. The paste-like electrode composition may be applied to only one side of a current collector or the like, or may be applied to both sides.

The paste-like electrode composition can be prepared by the same method as the slurry prepared for obtaining the composite particles by the above spray-drying granulation method.

The drying condition of the electrode composition layer formed by the application is not particularly limited and may be, for example, 1 hour or more at 120 ° C or more. Examples of the drying method include hot air, hot air, low-humidity air drying, vacuum drying, and drying by irradiation with (circle) infrared rays or electron beams.

It is preferable to coat the electrode composition on the current collector having the conductive adhesive layer and dry it, and then use a die press or a roll press to lower the porosity of the electrode by pressure treatment. The preferred range of porosity is 5% to 15%, more preferably 7% to 13%. By setting the porosity below this upper limit, the charging efficiency and the discharge efficiency can be increased. By setting the void ratio to be equal to or higher than the lower limit, a high volume capacity can be obtained and the peeling of the electrode can be reduced. When a curable polymer is used as the binder for the electrode composition layer, it is preferable to perform curing in addition to the drying step.

The density of the electrode composition layer used in the present invention is not particularly limited, but is usually from 0.30 to 10 g / cm 3, preferably from 0.35 to 5.0 g / cm 3, more preferably from 0.40 to 3.0 g / cm 3. The thickness of the electrode composition layer is not particularly limited, but is usually 5 to 1000 占 퐉, preferably 20 to 500 占 퐉, more preferably 30 to 300 占 퐉.

(Electrochemical device)

The electrochemical device of the present invention comprises the electrode for the electrochemical device, the separator, and the electrolyte solution. The electrochemical device is not particularly limited, but an electric double layer capacitor, a lithium ion capacitor, and a lithium ion secondary battery are preferable.

When the electrode for an electrochemical device of the present invention is used for a lithium ion capacitor, it is preferably used for a negative electrode. When it is used for a lithium ion secondary battery, it is preferably used for a positive electrode.

(Separator)

The separator is not particularly limited as long as it can insulate the electrodes for the electrochemical device and allow the positive and negative ions to pass therethrough. Concretely, a porous film made of a polyolefin such as polyethylene or polypropylene, a microporous film made of rayon or glass fiber or a nonwoven fabric, a pulp generally referred to as electrolytic capacitor paper as a main raw material, a polymeric coating on one side or both sides of the microporous film A porous film on which a porous coat layer containing an inorganic filler or an organic filler is formed on one side or both sides of the microporous membrane, and the like can be used. The separator is disposed between the electrodes for the electrochemical device so that the pair of electrode composition layers are opposed to each other, and a device is obtained. The thickness of the separator is appropriately selected depending on the intended use, and is usually 1 to 100 占 퐉, preferably 10 to 80 占 퐉, and more preferably 20 to 60 占 퐉.

(Electrolytic solution)

The electrolytic solution is usually composed of an electrolyte and a solvent. The electrolyte may be cationic, anionic, cationic or anionic.

Examples of cationic electrolytes include (1) imidazolium, (2) quaternary ammonium, (3) quaternary phosphonium, and (4) lithium.

(1) Imidazolium

1,3-dimethylimidazolium, 1-ethyl-3-methylimidazolium, 1,3-diethylimidazolium, 1,2,3-trimethylimidazolium, 1,2,3,4-tetra Methylimidazolium, 1,3,4-trimethyl-ethylimidazolium, 1,3-dimethyl-2,4-diethylimidazolium, 1,2-dimethyl- Methyl-2,3,4-triethylmethylimidazolium, 1,2,3,4-tetraethylimidazolium, 1,3-dimethyl-2-ethylimidazolium, 3-dimethylimidazolium, 1,2,3-triethylimidazolium, etc.

(2) quaternary ammonium

Tetraalkylammonium such as tetramethylammonium, ethyltrimethylammonium, diethyldimethylammonium, triethylmethylammonium, tetraethylammonium, trimethylpropylammonium and the like

(3) Quaternary phosphonium

Tetramethylphosphonium, tetraethylphosphonium, tetrabutylphosphonium, methyltriethylphosphonium, methyltributylphosphonium, dimethyldiethylphosphonium, etc.

(4) lithium

In addition, the anionic _{^{electrolyte, PF 6 -, BF 4 -}} , AsF 6 -, SbF 6 -, N (RfSO 3) 2-, C (RfSO 3) 3-, RfSO 3 - (Rf is a carbon number of 1 to each 12 fluoroalkyl groups), F ^- , ClO ₄ ^- , AlCl ₄ ^- , AlF ₄ ^- and the like can be used. These electrolytes may be used alone or in combination of two or more.

The solvent of the electrolytic solution is not particularly limited as long as it is generally used as a solvent for the electrolytic solution. Specific examples thereof include carbonates such as propylene carbonate, ethylene carbonate and butylene carbonate; lactones such as? -butyrolactone; Sulfolanes; Nitriles such as acetonitrile; . These may be used alone or as a mixed solvent of two or more kinds. Of these, carbonates are preferred.

The device is impregnated with an electrolytic solution to obtain the electrochemical device of the present invention. Concretely, the capacitor element can be manufactured by winding, stacking or bending the capacitor element, if necessary, into a container, and injecting and pouring the electrolyte into the container. The container may be impregnated with an electrolytic solution beforehand in a container. As the container, any known one such as a coin type, a cylindrical type, and a prism type can be used.

Example

Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to these examples. In the examples and comparative examples, parts and% are based on weight unless otherwise specified. The characteristics of the examples and comparative examples were measured by the following methods.

(Surface roughness Ra of the conductive adhesive layer)

The arithmetic average roughness (Ra) of the surface of the conductive adhesive layer was obtained by calculating the roughness curve by using a nano-scale hybrid microscope (VN-8010) manufactured by CHIENCE INC. Based on JIS B 0601 and calculating the following equation. L is the measurement length, and x is the deviation from the mean line to the measurement curve.

(Thickness of the conductive adhesive layer)

The current collector provided with the conductive adhesive layer was cut into 5 cm x 5 cm and the thickness of arbitrary 10 points was measured using a micro thickness gauge (manufactured by Toyo Seiki Seisaku-sho, Ltd.), and the thickness of the current collector Was taken as the thickness of the conductive adhesive layer.

(Appearance of the coated surface of the conductive adhesive layer)

The current collector on which the conductive adhesive layer was formed was cut out to 5 cm x 5 cm and the surface of the conductive adhesive layer was observed to count the crater portions (portions where the conductive adhesive was cratered and the current collector was exposed) Respectively.

A: The crater ring is not visible (crater ring position 0).

B: There is no problem in practical use, but there is a crater ring (the crater ring number is 1 to 10)

C: A lot of cratering points can be seen (cratering point 11 or more).

(Internal resistance of electric double layer capacitor)

An electric double layer capacitor of a laminate type laminate cell was manufactured using the electrode for electric double layer capacitor manufactured in the examples and the comparative example, and the battery was charged and discharged after standing for 24 hours, and the internal resistance was measured. Here, charging was started with a constant current of 2 A, and when the voltage reached 2.7 V, the voltage was maintained for 1 hour to perform constant-voltage charging. Also, discharging was performed immediately after the end of charging until the constant current 2 A was reached at 0 V. The internal resistance was calculated from the voltage drop immediately after discharge.

(Internal resistance of lithium ion capacitor)

A lithium ion capacitor of a laminate type laminate cell was produced by using electrodes for lithium ion capacitors manufactured in Examples and Comparative Examples, and the battery was left to stand for 24 hours, and charge and discharge operations were carried out to measure the internal resistance. Here, the charging is started with a constant current of 2 A, and when the voltage reaches 3.6 V, the voltage is maintained for 1 hour to make a constant-voltage charging. The discharging was carried out immediately after the end of charging until the constant current 2 A to 1.9 V was reached. The internal resistance was calculated from the voltage drop immediately after discharge.

(Internal resistance of lithium ion secondary battery)

A lithium ion secondary battery of a coin-type cell was manufactured using the electrode for a lithium ion secondary battery manufactured in Examples and Comparative Examples, and after the battery was left to stand for 24 hours, charging and discharging operations were carried out and the internal resistance was measured. Here, charging is started with a constant current of 10 mA, and when the voltage is attained to 4.2 V, the voltage is maintained for 1 hour to perform constant-voltage charging. The discharging was performed immediately after the end of charging until a constant current of 10 mA reached 3.0 V. The internal resistance was calculated from the voltage drop after 10 seconds of discharge.

(Peeling strength of electrode)

An electrode for an electric double layer capacitor, a negative electrode for a lithium ion capacitor or a positive electrode for a lithium ion secondary battery) having a length of 100 mm was formed so that the direction of formation of the electrode composition layer (the running direction of the current collector at the time of electrode formation) A cellophane tape (specified in JIS Z 1522) was stuck to the surface of the electrode composition layer with the electrode composition layer surface down, and one end of the current collector was cut in the vertical direction And the tensile strength was 50 mm / min. The stress was measured when peeling off (the cellophane tape was fixed to the test stand). The measurement was carried out three times, and the average value was obtained, and this was taken as the peel strength. The larger the peel strength, the greater the binding force of the electrode composition layer to the current collector, i.e., the higher the electrode strength.

(Example 1)

80 parts of spherical graphite having an aspect ratio of 7 and a volume average particle diameter of 1.0 mu m (manufactured by Nippon Kayaku Co., Ltd.) as the spherical graphite, and 100 parts of a furnace black (Super-P; manufactured by Timcal Co.) having a volume- , 4 parts of a 4.0% aqueous solution of carboxymethylcellulose ammonium (DN-10L, manufactured by Daicel Chemical Industries, Ltd.) as a dispersant, and 4 parts as a binder, and having a glass transition temperature of -40 캜 and a number average particle size of 0.25 (Copolymer obtained by emulsion polymerization of a monomer mixture containing 60% by weight of styrene, 35% by weight of butadiene, and 5% by weight of itaconic acid) of a carboxylic acid group-containing diene polymer The exchanged water was mixed to have a total solid content concentration of 30% to prepare a conductive adhesive composition.

The conductive adhesive composition was discharged from a die into an aluminum current collector having a thickness of 30 占 퐉 and coated on one side of the current collector at a molding speed of 30 m / min and dried at 120 占 폚 for 5 minutes to obtain a conductive adhesive agent Layer. Table 1 shows the appearance of the coated surface of the conductive adhesive layer and the measurement results of the surface roughness Ra of the conductive adhesive layer.

On the other hand, 100 parts of an activated carbon powder (CEP-21; manufactured by Shin-Nippon Kogyo Co., Ltd.) having an average particle diameter of 11 탆, which is an alkali activated carbon having a petroleum pitch as a raw material, and 100 parts of carboxymethylcellulose ammonium 2 parts of a 1.5% aqueous solution (DN-800H; manufactured by Daicel Chemical Industries, Ltd.) in an amount corresponding to the solid content, 5 parts of acetylene black (Denka black powder, manufactured by Denki Kagaku Kogyo K.K.) as a conductive agent, (A copolymer obtained by emulsion polymerization of a monomer mixture containing 60% by weight of styrene, 35% by weight of butadiene and 5% by weight of itaconic acid) having a number average molecular weight of -40 캜 and a number average particle diameter of 0.25 탆, 5 parts by weight in terms of solid content, and ion-exchanged water were mixed by a planetary mixer so that the total solid content concentration was 20%, thereby preparing a slurry for an electrode composition layer.

Then, the slurry was passed through a rotary disk-type atomizer (diameter 65 mm) at a rotation speed of 25,000 rpm, a hot air temperature of 150 ° C, and a temperature of the particle recovery outlet 90 ° C, to obtain a spherical composite particle (electrode composition) for electrode composition layer having a volume average particle diameter of 56 탆 and a sphericity of 93%.

The composite particles were coated on a roll (roll temperature of 100 占 폚, press line pressure of 3.9 kN / cm) of a roll press machine (press cutting roughened surface hot roll; manufactured by Hirono Kikai Co., Ltd.) And the sheet-like electrode composition layer was formed on the conductive adhesive layer at a molding speed of 20 m / min. The resultant sheet was pressed with a square of 5 cm to obtain an electric double layer capacitor having an electrode composition layer with a thickness of 200 mu m An electrode was obtained. Table 1 shows the measurement results of the peel strength of the electrode for electric double-layer capacitor.

Cellulose (TF40; manufactured by Nippon Gohto Kogyo Co., Ltd.) was impregnated with the electrolytic solution for 1 hour at room temperature as an electrode for the electric double layer capacitor and a separator. Then, the electrode composition layers of the two electrodes for the electric double layer capacitor were opposed to each other with the separator interposed therebetween, and the electrodes for the respective electric double layer capacitors were arranged so as not to come into electrical contact with each other to produce a laminated cell type electric double layer capacitor. As the electrolyte, propylene carbonate was used as a solvent and tetraethylammonium fluoroborate was dissolved at a concentration of 1.0 mol / liter. Table 1 shows the measurement results of the internal resistance of this electric double layer capacitor.

(Example 2)

Except that the spherical graphite constituting the conductive adhesive layer was replaced by spherical graphite having an aspect ratio of 2 and a volume average particle size of 3.7 탆 (HPC-250, manufactured by Nippon Graphite Industry Co., Ltd.) Electrode and an electric double layer capacitor were prepared. Table 1 shows the external appearance of the coated surface of the conductive adhesive layer, the surface roughness Ra of the conductive adhesive layer, the peel strength of the electrode for the electric double layer capacitor, and the internal resistance of the electric double layer capacitor.

(Example 3)

Except that spheroidal graphite constituting the conductive adhesive layer was replaced with spherical graphite (LB-CG; manufactured by Nippon Graphite Industry Co., Ltd.) having an aspect ratio of 3 and a volume average particle size of 18 탆, Electrode and an electric double layer capacitor were prepared. Table 1 shows the external appearance of the coated surface of the conductive adhesive layer, the surface roughness Ra of the conductive adhesive layer, the peel strength of the electrode for the electric double layer capacitor, and the internal resistance of the electric double layer capacitor.

(Example 4)

An electrode for an electric double layer capacitor and an electric double layer capacitor were produced in the same manner as in Example 2 except that the amount of the spherical graphite constituting the conductive adhesive layer was 95 parts and the amount of the carbon black was 5 parts. Table 1 shows the external appearance of the coated surface of the conductive adhesive layer, the surface roughness Ra of the conductive adhesive layer, the peel strength of the electrode for the electric double layer capacitor, and the internal resistance of the electric double layer capacitor.

(Example 5)

An electrode for an electric double layer capacitor and an electric double layer capacitor were produced in the same manner as in Example 2 except that the amount of the spherical graphite constituting the conductive adhesive layer was 50 parts and the amount of the carbon black was 50 parts. Table 1 shows the external appearance of the coated surface of the conductive adhesive layer, the surface roughness Ra of the conductive adhesive layer, the peel strength of the electrode for the electric double layer capacitor, and the internal resistance of the electric double layer capacitor.

(Example 6)

Except that carbon black constituting the conductive adhesive layer was replaced with acetylene black (BMAB; manufactured by Denki Kagaku Kogyo Kabushiki Kaisha) having a volume average particle diameter of 0.4 탆 and containing 1% of boron, the electric double layer capacitor electrode And an electric double layer capacitor. Table 1 shows the external appearance of the coated surface of the conductive adhesive layer, the surface roughness Ra of the conductive adhesive layer, the peel strength of the electrode for the electric double layer capacitor, and the internal resistance of the electric double layer capacitor.

(Example 7)

The carbon black constituting the conductive adhesive layer was changed to acetylene black (BMAB; manufactured by Denki Kagaku Kogyo K.K.) having a volume average particle diameter of 0.4 μm and containing 1% of boron, and the conductive adhesive composition was further mixed with an anionic surfactant, naphthalenesulfonic acid formalin An electrode for an electric double layer capacitor and an electric double layer capacitor were produced in the same manner as in Example 2 except that 4 parts of water (Demol NL; Kao Corporation) was added in an amount corresponding to the solid content. Table 1 shows the external appearance of the coated surface of the conductive adhesive layer, the surface roughness Ra of the conductive adhesive layer, the peel strength of the electrode for the electric double layer capacitor, and the internal resistance of the electric double layer capacitor.

(Example 8)

The binder constituting the conductive adhesive layer was formed by mixing a carboxylic acid group-containing acrylate polymer having a glass transition temperature of -45 占 폚 and a number average particle size of 0.25 占 퐉 (96 weight% of 2-ethylhexyl acrylate, 4 weight% , And the carbon black constituting the conductive adhesive layer was changed to a 40% aqueous dispersion of acetylene black (BMAB: electrochemical) having a volume average particle diameter of 0.4 μm and containing 1% of boron Except that 4 parts of naphthalenesulfonic acid formalin condensate (Demol NL; manufactured by Kao Corp.), which is an anionic surfactant, was added to the conductive adhesive composition in an amount corresponding to the solid content, and the electric double layer capacitor Electrode and an electric double layer capacitor were prepared. Table 1 shows the external appearance of the coated surface of the conductive adhesive layer, the surface roughness Ra of the conductive adhesive layer, the peel strength of the electrode for the electric double layer capacitor, and the internal resistance of the electric double layer capacitor.

(Example 9)

The binder constituting the conductive adhesive was changed to an acrylate polymer having a carboxyl group and a nitrile group having a glass transition temperature of -20 占 폚 and a number average particle diameter of 0.25 占 퐉 (76 weight% of 2-ethylhexyl acrylate, 20 weight% of acrylonitrile 20 % By weight, and 4% by weight of itaconic acid) was changed to a 40% aqueous dispersion of carbon black constituting the conductive adhesive layer with a volume average particle diameter of 0.4 μm and a boron content of 1% Except that 4 parts of naphthalenesulfonic acid formalin condensate (Demol NL manufactured by Kao Corporation), which is an anionic surfactant, was added to the conductive adhesive composition in an amount corresponding to the solid content, As in Example 2, an electrode for an electric double layer capacitor and an electric double layer capacitor were prepared. Table 1 shows the external appearance of the coated surface of the conductive adhesive layer, the surface roughness Ra of the conductive adhesive layer, the peel strength of the electrode for the electric double layer capacitor, and the internal resistance of the electric double layer capacitor.

(Comparative Example 1)

Graphite (KS-6; manufactured by Timcal Co., Ltd.) having an aspect ratio of 38 and a volume average particle size of 4.0 탆 was used as the flaky graphite constituting the conductive adhesive layer, and carbon black having a volume average particle diameter of 0.4 탆 (Acetylene black; manufactured by DENKI KAGAKU KOGYO KABUSHIKI KAISHA) as a binder and a diene polymer having a glass transition temperature of -48 DEG C and a number average particle diameter of 0.25 mu m (65 wt% of styrene, 35 wt% of butadiene Was used in place of the 40% aqueous dispersion of the aqueous dispersion of the electric double-layer capacitor and the 40% aqueous dispersion of the aqueous dispersion of the electric double-layer capacitor. Table 1 shows the external appearance of the coated surface of the conductive adhesive layer, the surface roughness Ra of the conductive adhesive layer, the peel strength of the electrode for the electric double layer capacitor, and the internal resistance of the electric double layer capacitor.

(Example 10)

80 parts of graphite having an aspect ratio of 2 and a volume average particle size of 3.7 탆 (HPC-250, manufactured by Nippon Graphite Industry Co., Ltd.) as the spherical graphite, 0.5 parts of acetylene black containing 1% of boron having a volume average particle diameter of 0.4 탆 (Manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) as a dispersant, 4 parts of an aqueous solution of carboxymethylcellulose ammonium (DN-10L; manufactured by Daicel Chemical Industries, Ltd.) as a dispersing agent, 0.1 part of naphthalenesulfonic acid 4 parts of a formalin condensate (Demol NL; manufactured by Kao Corp.) in an amount corresponding to the solid content, 4 parts of an acrylate polymer having a carboxylic acid group and a nitrile group having a glass transition temperature of -20 占 폚 and a number average particle diameter of 0.25 占 퐉 A copolymer obtained by emulsion polymerization of a monomer mixture containing 76 wt% of 2-ethylhexyl, 20 wt% of acrylonitrile and 4 wt% of itaconic acid) 8 parts of a 40% water dispersion corresponding to the solid content, and ion-exchanged water to a total solid content concentration of 30% to prepare a conductive adhesive composition.

The conductive adhesive composition was discharged from a pair of dies so as to interpose an expandable aluminum current collector (opening ratio: 40%) having a thickness of 30 占 퐉 and applied on both surfaces of the current collector at a molding speed of 30 m / Lt; 0 > C for 5 minutes to form a conductive adhesive layer having a single-sided thickness of 4 mu m.

On the other hand, 100 parts of an activated carbon powder (CEP-21; manufactured by Shin-Nippon Kogyo Co., Ltd.) having an average particle size of 11 탆, which is an alkali activated carbon having a petroleum pitch as a raw material, 100 parts of carboxymethylcellulose ammonium as a dispersant, 2.0 parts of an aqueous solution (DN-800H; manufactured by Daicel Chemical Industries, Ltd.) corresponding to the solid content, 5 parts of acetylene black (Denka Black dispersion, manufactured by Denki Kagaku Kogyo K.K.) as a conductive agent, 5 parts of a 40% aqueous dispersion of a diene polymer having a number average particle diameter of 0.25 탆 (a copolymer obtained by emulsion polymerization of 60% by weight of styrene, 35% by weight of butadiene and 5% by weight of itaconic acid) And ion-exchanged water were mixed by a planetary mixer so that the total solid content concentration was 20% to prepare a slurry for the electrode composition layer of the positive electrode.

Then, the slurry was passed through a rotary disk-type atomizer (diameter 65 mm) at a rotation speed of 25,000 rpm, a hot air temperature of 150 ° C, and a temperature of the particle recovery outlet 90 ° C, to obtain composite particles (electrode composition) for electrode composition layer of spherical positive electrode having a volume average particle size of 56 탆 and a sphericity of 93%.

The composite particles were coated on a roll (roll temperature: 100 占 폚, press line pressure: 3.9 kN / cm) of a roll press machine (manufactured by Hirano Kikai K.K.) using a roll press machine And the sheet-like electrode composition layer was formed on the conductive adhesive layer at a forming speed of 20 m / min. This was spun in a 5 cm square to obtain a positive electrode having an electrode composition layer with a thickness of 200 mu m, ≪ / RTI >

On the other hand, the conductive adhesive composition was discharged from a pair of dies so as to interpose an expanded copper current collector (aperture ratio: 40%) having a thickness of 20 占 퐉 and applied on both surfaces of the current collector at a molding speed of 30 m / And dried at 120 DEG C for 5 minutes to form a conductive adhesive layer having a single-sided thickness of 4 mu m. Table 2 shows the appearance of the coated surface of the conductive adhesive layer and the measurement results of the surface roughness Ra of the conductive adhesive layer.

On the other hand, 100 parts of graphite (KS-6; manufactured by Timcal Co., Ltd.) having a volume average particle diameter of 3.7 탆 and a 1.5% aqueous solution of carboxymethylcellulose ammonium (DN-800H; manufactured by Daicel Chemical Industries, Ltd.) (Trade name; manufactured by Denki Kagaku Kogyo Seiyaku Co., Ltd.) as a conductive agent, 2.0 parts of a diene polymer having a glass transition temperature of -40 占 폚 and a number average particle diameter of 0.25 占 퐉 (styrene 60 5 parts by weight of a 40% aqueous dispersion of a copolymer obtained by emulsion-polymerizing a monomer mixture containing 50% by weight of a monomer mixture containing 35% by weight of butadiene and 5% by weight of itaconic acid, and 20% And mixed with a planetary mixer as much as possible to prepare a slurry for an electrode composition layer.

Then, the slurry was passed through a rotary disk-type atomizer (diameter 65 mm) at a rotation speed of 25,000 rpm, a hot air temperature of 150 ° C, and a temperature of the particle recovery outlet 90 deg. C to obtain composite particles (electrode composition) for electrode composition layer of a spherical negative electrode having a volume average particle size of 28 mu m and a sphericity of 93%.

The composite particles were coated on a roll (roll temperature of 100 占 폚, press line pressure of 3.9 kN / cm) of a roll press machine (manufactured by Hirano Kikai K.K.) using a roll press machine And the sheet-like electrode composition layer was formed on the conductive adhesive layer at a molding speed of 20 m / min. The sheet was then pressed with a square of 5 cm to obtain a negative electrode having an electrode composition layer with a single- An electrode was obtained. Table 2 shows the measurement results of the peel strength of the electrode for the lithium ion capacitor of this negative electrode.

A lithium ion capacitor electrode for the positive electrode, a lithium ion capacitor electrode for the negative electrode, and a cellulose / rayon nonwoven fabric as a separator were impregnated with the electrolytic solution for 1 hour at room temperature. Then, the positive electrode 10 set and the negative electrode 10 set were set so that the electrode for the lithium ion capacitor of the positive electrode and the electrode for the lithium ion capacitor of the negative electrode were opposed to each other with the separator interposed therebetween and the electrodes for the respective lithium ion capacitors were not in electrical contact Thereby preparing a lithium ion capacitor in the form of a laminate laminate cell. As the electrolyte, ethylene carbonate, diethyl carbonate and propylene carbonate were mixed at a weight ratio of 3: 4: 1, and LiPF ₆ dissolved in a concentration of 1.0 mol / liter was used.

(Thickness 82 占 퐉, length 5 cm 占 5 cm in width) on a stainless steel net having a thickness of 80 占 퐉 was used as the lithium electrode of the laminate type laminate cell, and the lithium electrode was laminated so as to completely face the outermost negative electrode One electrode was placed on the top and bottom of one electrode. In addition, the terminal welding portion (two pieces) of the lithium electrode current collector was resistance welded to the negative electrode terminal welding portion. Table 2 shows the measurement results of the internal resistance of the lithium ion capacitor.

(Comparative Example 2)

An electrode for a lithium ion capacitor and a lithium ion capacitor were produced in the same manner as in Example 10 except that the conductive adhesive composition obtained in Comparative Example 1 was used. Table 2 shows the external appearance of the coated surface of the conductive adhesive layer, the surface roughness Ra of the conductive adhesive layer, the peeling strength of the electrode for the lithium ion capacitor of the negative electrode, and the internal resistance of the lithium ion capacitor.

(Example 11)

80 parts of graphite having an aspect ratio of 2.5 and a volume average particle size of 2.0 탆 (manufactured by Nippon Graphite Kogyo Co., Ltd.) as the spherical graphite, 0.5 parts of acetylene black having a volume average particle diameter of 0.4 탆 and containing 1% (DN-10L; manufactured by Daicel Chemical Industries, Ltd.) as a dispersant, 4 parts by weight of a solid component, and a binder resin having a glass transition temperature of -20 占 폚 and a number of water (Obtained by emulsion polymerization of a monomer mixture containing 76 wt% of 2-ethylhexyl acrylate, 20 wt% of acrylonitrile and 4 wt% of itaconic acid) containing an acrylate polymer having a carboxylic acid group and nitrile group having an average particle size of 0.25 μm 8 parts of a 40% water dispersion corresponding to the solid content, and an anionic surfactant, naphthalenesulfonic acid formalin condensate (Demol NL; Kao Corp.) 4 parts and ion-exchanged water were mixed so as to have a total solid content concentration of 30% to prepare a conductive adhesive composition.

On the aluminum foil having a thickness of 30 占 퐉, the above-mentioned conductive adhesive composition was applied on one side of the aluminum foil at a molding speed of 30 m / min and dried at 120 占 폚 for 5 minutes to form a conductive adhesive layer having a thickness of 4 占 퐉 . Table 3 shows the appearance of the coated surface of the conductive adhesive layer and the measurement results of the surface roughness Ra of the conductive adhesive layer.

100 parts of LiFePO ₄ having an olivine crystal structure and a 1% aqueous solution of carboxymethylcellulose ("CMC", "BSH-12" manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) as a positive electrode active material, 1 part, an acrylate polymer having a glass transition temperature of -40 占 폚 and a number average particle diameter of 0.20 占 퐉 (78 weight% of 2-ethylhexyl acrylate, 20 weight% of acrylonitrile, 2 weight% of methacrylic acid as binder) , 5 parts of a 40% aqueous dispersion of the copolymer in an amount corresponding to the solid content, and 40% of the total solid content in ion-exchanged water were mixed by a planetary mixer to obtain a slurry for electrode composition layer .

The slurry for the electrode composition layer of the positive electrode was coated on one side of the conductive adhesive layer formed on the aluminum foil with a comma coater and dried at 120 DEG C for 20 minutes to form a positive electrode active material layer having a thickness of 60 mu m. This was rolled by a roll press to obtain a negative electrode for negative electrode having a thickness of the positive electrode active material layer of 45 mu m. The obtained positive electrode green sheet was cut into a circle having a diameter of 13 mm, and used as a positive electrode for a lithium ion secondary battery. Table 3 shows the measurement results of the peel strength of the positive electrode for this lithium ion secondary battery.

100 parts of graphite (KS-6; manufactured by Timcal Co., Ltd.) having a volume average particle diameter of 3.7 탆 and a 1.5% aqueous solution of carboxymethylcellulose ammonium (DN-800H; manufactured by Daicel Chemical Industries, Ltd.) (Styrene 60% by weight) having a glass transition temperature of -40 占 폚 and a number average particle diameter of 0.25 占 퐉 was used as a binder, , A copolymer obtained by emulsion-polymerizing a monomer mixture containing 35% by weight of butadiene and 5% by weight of itaconic acid) in an amount of 5 parts by weight corresponding to the solid content, and a planarizer Were mixed by a rotary mixer to prepare a slurry for an electrode composition layer of negative electrode.

On one side of the copper foil having a thickness of 20 占 퐉, the slurry for the electrode composition layer of the negative electrode was coated with a comma coater and dried at 110 占 폚 for 20 minutes to form a negative electrode active material layer having a thickness of 90 占 퐉. This was rolled by a roll press to obtain a negative electrode disk having a thickness of 60 m of the negative electrode active material layer. The thus-obtained disk for negative electrode was cut into a circular shape having a diameter of 14 mm, and used as a negative electrode for a lithium ion secondary battery.

A single-layered polypropylene separator (width 65 mm, length 500 mm, thickness 25 占 퐉, manufactured by the dry method, porosity of 55%) was cut into a circle having a diameter of 18 mm.

The obtained positive electrode for a lithium ion secondary battery was disposed on the bottom surface of the outer container so that the side of the conductive adhesive layer side was in contact with the outer container. A separator was disposed on the surface of the positive electrode opposite to the positive electrode active material layer. Further, the negative electrode for a lithium ion secondary battery obtained above was placed on the separator so that the side of the negative electrode active material layer side was opposed to the separator. A stainless steel cap having a thickness of 0.2 mm was covered and fixed to the outer container through a polypropylene packing for sealing the opening of the outer container and the container was sealed to obtain a lithium ion secondary battery having a diameter of 20 mm and a thickness of about 3.2 mm A battery was prepared. Table 3 shows the results of measurement of the internal resistance of this lithium ion secondary battery.

(Example 12)

Except that the spherical graphite constituting the conductive adhesive layer was replaced with graphite (JB-5, manufactured by Nippon Graphite Industry Co., Ltd.) having an aspect ratio of 1.7 and a volume average particle size of 4.0 탆, A negative electrode, a positive electrode for a lithium ion secondary battery, and a lithium ion secondary battery. Table 3 shows the external appearance of the coated surface of the conductive adhesive layer, the surface roughness Ra of the conductive adhesive layer, the peeling strength of the positive electrode for the lithium ion secondary battery, and the internal resistance of the lithium ion secondary battery.

(Example 13)

Except that the spherical graphite constituting the conductive adhesive layer was replaced with graphite having an aspect ratio of 1.9 and a volume average particle diameter of 8.0 占 퐉 (manufactured by Nippon Graphite Kogyo Co., Ltd.) as in Example 11, a negative electrode for a lithium ion secondary battery, A positive electrode for a secondary battery and a lithium ion secondary battery were manufactured. Table 3 shows the external appearance of the coated surface of the conductive adhesive layer, the surface roughness Ra of the conductive adhesive layer, the peeling strength of the positive electrode for the lithium ion secondary battery, and the internal resistance of the lithium ion secondary battery.

(Example 14)

A negative electrode for a lithium ion secondary battery and a negative electrode for a lithium ion secondary battery were prepared in the same manner as in Example 12 except that the surfactant constituting the conductive adhesive layer was replaced with a nonionic surfactant polyoxyethylene alkylamine (Amide 105, A positive electrode for a secondary battery and a lithium ion secondary battery were manufactured. Table 3 shows the external appearance of the coated surface of the conductive adhesive layer, the surface roughness Ra of the conductive adhesive layer, the peeling strength of the positive electrode for the lithium ion secondary battery, and the internal resistance of the lithium ion secondary battery.

(Comparative Example 3)

(KS-6; manufactured by Timcal Co., Ltd.) having an aspect ratio of 38 and a volume average particle size of 4.0 탆 was used as the graphite constituting the conductive adhesive layer, and carbon black having a volume average particle diameter of 0.4 탆 Acetylene black manufactured by DENKI KEMIC INDUSTRIES, LTD.) As a binder, and a diene polymer having a glass transition temperature of -48 DEG C and a number average particle diameter of 0.25 mu m (65 wt% of styrene, 35 wt% of butadiene, A negative electrode for a lithium ion secondary battery, a positive electrode for a lithium ion secondary battery, and a lithium ion secondary battery (a copolymer obtained by emulsion polymerization) were used in the same manner as in Example 11 except that a 40% A battery was prepared. Table 3 shows the external appearance of the coated surface of the conductive adhesive layer, the surface roughness Ra of the conductive adhesive layer, the peeling strength of the positive electrode for the lithium ion secondary battery, and the internal resistance of the lithium ion secondary battery.

(Comparative Example 4)

(KS-6; manufactured by Timcal Co., Ltd.) having an aspect ratio of 38 and a volume average particle size of 4.0 탆 was used as the graphite constituting the conductive adhesive layer, and carbon black having a volume average particle diameter of 0.4 탆 Acetylene black (manufactured by Electrochemical Industries, Ltd.) was used, and as the binder, an acrylic polymer having a glass transition temperature of -50 占 폚 and a number average particle diameter of 0.25 占 퐉 (90% by weight of 2-ethylhexyl acrylate, 5% by weight of methyl methacrylate %, Acrylonitrile 3% by weight, and methacrylic acid 2% by weight) was used and a surfactant was not used. Similarly, a negative electrode for a lithium ion secondary battery, a positive electrode for a lithium ion secondary battery, and a lithium ion secondary battery were produced. Table 3 shows the external appearance of the coated surface of the conductive adhesive layer, the surface roughness Ra of the conductive adhesive layer, the peeling strength of the positive electrode for the lithium ion secondary battery, and the internal resistance of the lithium ion secondary battery.

As is clear from the above examples and comparative examples, when the electrode for an electrochemical device of the present invention is used, the electrode strength (= large peeling strength) is excellent, the electrode density is improved (= energy density is high) It is possible to reduce the resistance (= increase the output density).

Among the examples, the carbon black constituting the conductive adhesive layer contains a heteroatom, and an acrylate polymer containing a carboxylic acid group and a nitrile group is used as the binder, and also carboxymethylcellulose ammonium and anionic surfactant Examples 9 to 13 using the active agent are particularly excellent in productivity (= appearance of the coated surface of the conductive adhesive layer), electrode strength and internal resistance.

On the other hand, in the case of using flaky graphite as the graphite constituting the conductive adhesive layer (Comparative Examples 1 to 4), productivity, electrode strength, electrode density and internal resistance are both inferior.

Claims (16)

A conductive adhesive layer comprising a spherical graphite, carbon black and a binder for a conductive adhesive layer, and
The electrode composition layer comprising the electrode active material and the binder for the electrode composition layer,
An electrode for an electrochemical device comprising, on the current collector, a conductive adhesive layer and an electrode composition layer in this order from the collector side,
Wherein the weight ratio of the spheroidal graphite and the carbon black in the conductive adhesive layer is 0.05 to 1.0 in terms of the ratio of carbon black to spheroidal graphite,
Wherein the binder for the conductive adhesive layer has a polar group and the polar group is a nitrile group. The method according to claim 1,
Wherein the spherical graphite has a volume average particle diameter of 0.1 to 50 占 퐉. 3. The method according to claim 1 or 2,
Wherein the carbon black contains a hetero element. The method of claim 3,
Wherein the content of the hetero element in the carbon black is 0.01 to 20 wt%. 3. The method according to claim 1 or 2,
Wherein the binder for the conductive adhesive layer is an acrylate polymer or a diene polymer. delete delete delete delete 3. The method according to claim 1 or 2,
Wherein the conductive adhesive layer further comprises a carboxymethyl cellulose salt. 3. The method according to claim 1 or 2,
Wherein the conductive adhesive layer further comprises a surfactant. 12. The method of claim 11,
Wherein the surfactant is an anionic surfactant. 3. The method according to claim 1 or 2,
Wherein the current collector has a hole penetrating therethrough. 3. The method according to claim 1 or 2,
Wherein the electrode composition layer is composed of composite particles comprising an electrode active material and a binder for an electrode composition layer. An electrochemical device comprising the electrode for an electrochemical device according to claim 1 or 2, a separator, and an electrolytic solution. delete