JP2005340188A - Electrode, electrochemical device, and manufacturing method of electrode - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrode capable of sufficiently reducing contact resistance of a particle containing an active material and a collector, an electrochemical device provided with the electrode, and a manufacturing method of the electrode. <P>SOLUTION: This electrode 2 is equipped with a plate-shaped collector 22 and an active material containing layer 24. The active material contained layer 24 has a plurality of particles 25 containing the active material and a binder 27 for binding the particles 25 containing the active material each other and also for binding the particles containing the active material and the collector 22, and the surface of the collector 22 is depressed in conformity with the shape of the particle 25 containing the active material. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electrode that can be used in an electrochemical device such as a primary battery, a secondary battery (especially, a lithium ion secondary battery), an electrolysis cell, or a capacitor (especially an electrochemical capacitor), and an electrochemical equipped with the electrode. The present invention relates to a device and a method for manufacturing an electrode.

  Electrochemical devices such as high energy batteries such as lithium ion secondary batteries and electrochemical capacitors including electric double layer capacitors are widely used in portable devices and the like. Such an electrochemical device mainly includes a pair of electrodes and an electrolyte (for example, a liquid electrolyte or a solid electrolyte) interposed between the electrodes.

Such an electrode of an electrochemical device is usually formed by laminating an active material-containing layer on a plate-like current collector, and the active material-containing layer includes a large number of particles containing the active material. As a method for producing such an electrode, a kneaded material containing particles containing an active material, a binder and conductive auxiliary agent particles is prepared, and the kneaded material is rolled by a hot roll machine and / or a hot press machine. A method of forming a substance-containing sheet and bonding the active material-containing sheet to a current collector has been proposed (see, for example, Patent Document 1).
JP 2004-2105 A

  However, it has been found that the electrode manufactured by the above-described method has a relatively high contact resistance between the particles containing the active material and the current collector. When such an electrode is used for an electrochemical device, the internal resistance of the electrochemical device increases, which may hinder high output and high energy density of the electrochemical device.

  The present invention has been made in view of the above problems, and provides an electrode that can sufficiently reduce the contact resistance between particles containing an active material and a current collector, an electrochemical device including the electrode, and a method for producing the electrode. The purpose is to provide.

  As a result of intensive studies to achieve the above object, the present inventors have found the following. That is, a conventional active material-containing sheet obtained by rolling a raw material kneaded material with a pair of rolls has a relatively smooth surface, and a conventional electrode has an active material-containing sheet having a relatively smooth surface, a plate The current collector is bonded to the shape. Therefore, the contact area between the active material-containing sheet and the current collector is not sufficient, and the contact resistance between the particles containing the active material and the current collector is increased.

  Therefore, an electrode according to the present invention includes a plate-like current collector and an active material-containing layer provided on the current collector, and the active material-containing layer includes a plurality of particles containing an active material, and It has a binder that binds particles containing active materials to each other and particles containing these active materials, and the surface of the current collector follows the shape of the particles containing these active materials. It is depressed.

  The electrochemical device according to the present invention includes a pair of electrodes and an electrolyte interposed between the electrodes, and at least one of the pair of electrodes includes a plurality of active material-containing layers containing an active material. Particles, and a binder that binds the particles containing these active materials to each other and binds the particles containing these active materials and the current collector, and the surface of the current collector is composed of particles containing these active materials. It is recessed along the shape.

  In such an electrode, since the current collector is recessed along the shape of the particle containing the active material, the contact area between the particle containing the active material and the current collector can be increased. Therefore, the contact resistance between the particles containing the active material and the current collector can be reduced as compared with the conventional case. Thereby, the internal resistance of the electrochemical device using such an electrode can be reduced, and the output of the electrochemical device can be increased and the energy density can be improved.

  Here, it is preferable that conductive agent particles are contained in the binder in the active material-containing layer, because a conductive path is further formed between the particles containing the active material and the current collector to further reduce the contact resistance. . Further, a conductive path is further formed between the particles containing the active material, and the contact resistance between the particles containing the active material can be reduced, so that the resistance of the active material containing layer itself can be greatly reduced, which is more preferable.

  Moreover, it is preferable that the particle size of the particle | grains containing the active material in an active material content layer is 0.1-500 micrometers. If the particle diameter of the particles containing the active material is less than 0.1 μm, the particles containing the active material tend to aggregate and the particles containing the active material tend not to be uniformly dispersed in the active material-containing layer. There is. In particular, when the conductive material particles are included in the active material-containing layer, the contact between the particles containing the active material and the conductive material particles becomes uneven, and the particles containing the active material, the conductive material particles In addition, the contact between the binders becomes non-uniform, and there is a case where a problem occurs in each adhesion. On the other hand, when the diameter of the particle containing the active material exceeds 500 μm, the diffusion resistance of the electrolyte or the like in the particle containing the active material tends to increase, and the specific surface area of the particle containing the active material also increases. There is a tendency to become smaller. Therefore, it is difficult to increase the capacity of the electrochemical device.

  On the other hand, the method for producing an electrode according to the present invention includes a particle layer laminating step of laminating a particle layer containing a plurality of particles containing a binder and an active material that are melted by heating with respect to a plate-like current collector, While heating the particle layer, the current layer and the particle layer are passed between rotating rolls to roll the particle layer, and particles containing the active material are bonded together with a binder and particles containing the active material And a roll step of binding the current collector with a binder.

  According to the present invention, the particles containing the active material are pressed against the current collector in the roll process, and the particles containing the active material sink into the surface of the current collector. Therefore, an electrode in which the surface of the current collector as described above is recessed along the shape of the particle containing the active material can be preferably produced. In addition, since the formation of the active material-containing layer and the bonding (adhesion) of the active material-containing layer and the current collector can be performed at the same time, the number of steps can be reduced as compared with the conventional case, and the cost can be reduced.

  Here, in the particle layer laminating step, when the particle layer further contains conductive auxiliary agent particles, as described above, an electrode in which the conductive auxiliary agent particles are included in the binder is obtained. Such an electrode is more preferable because it can further reduce the contact resistance between the particles containing the active material and the current collector, and can also reduce the contact resistance between the particles containing the active material.

  At this time, it is preferable that the particle layer includes a plurality of composite particles obtained by previously integrating particles containing the active material with a binder including conductive auxiliary agent particles.

  According to this, in the composite particles in advance, the particles containing the active material and the conductive auxiliary particles can be well dispersed, so by hot rolling the particle layer of such composite particles, An extremely good electronic conductive path can be formed in the active material-containing layer. Therefore, the resistance of the active material-containing layer can be further reduced.

  In addition, it is preferable to perform the roll process by passing the current collector and the particle layer between heated rolls, because heating and the roll can be performed with one apparatus.

In the roll process, the linear pressure applied between the rolls is preferably 200 × 10 ^{2 to} 2000 × 10 ² N / m (about 20 to 200 kgf / cm). Here, when the linear pressure of the roll is less than 200 × 10 ² N / m, there is a tendency that particles containing the active material are not sufficiently embedded in the current collector. On the other hand, when the linear pressure of the roll exceeds 2000 × 10 ² N / m, the active material-containing layer tends to be excessively consolidated and the electrolyte does not easily diffuse in the active material-containing layer. Therefore, the impedance can be sufficiently lowered within the above range.

  In the particle layer laminating step, a binder layer that contains conductive auxiliary particles and is melted by heating is provided on the surface of the current collector in advance, and it is preferable to laminate the particle layer on this binder layer.

  According to this, since the binder layer is also melted during the hot rolling, the particles containing the active material and the current collector can be bonded better. At this time, the particles containing the active material are immersed in the melted binder layer and further embedded in the current collector. Moreover, since the binder layer contains the conductive auxiliary agent particles, even if such a binder layer is adopted, the contact resistance between the particles containing the active material and the current collector can be sufficiently reduced.

  Moreover, it is preferable when the particle diameter of the particle | grains containing an active material shall be 0.1-500 micrometers. If the particle diameter of the particles containing the active material is less than 0.1 μm, the particles containing the active material tend to aggregate and the particles containing the active material tend not to be uniformly dispersed in the active material-containing layer. There is. In particular, when the conductive material particles are included in the active material-containing layer, the contact between the particles containing the active material and the conductive material particles becomes uneven, and the particles containing the active material, the conductive material particles In addition, the contact between the binders becomes non-uniform, and there is a case where a problem occurs in each adhesion. On the other hand, when the diameter of the particle containing the active material exceeds 500 μm, the diffusion resistance of the electrolyte or the like in the particle containing the active material tends to increase, and the specific surface area of the particle containing the active material also increases. Get smaller. Therefore, it is difficult to increase the capacity of the electrochemical device.

  Here, in the present invention, the “active material” indicates the following materials depending on the electrode to be formed. That is, when the electrode to be formed is an electrode used as the anode of the primary battery, the “active material” indicates a reducing agent, and when the electrode is the cathode of the primary battery, the “active material” indicates an oxidizing agent. Show. Further, the “particles containing an active material” can contain substances other than the active material to the extent that the function of the active material is not impaired.

  Further, when the electrode to be formed is an anode (during discharge) used for a secondary battery, the “active material” is a reducing agent and is chemically active in both the reduced form and the oxidized form. It is a substance that can exist stably, and indicates a substance that can reversibly proceed from a reduction reaction from an oxidant to a reductant and from a reductant to an oxidant. Furthermore, when the electrode to be formed is a cathode (during discharge) used in a secondary battery, the “active material” is an oxidant and is chemically active in any of its reduced and oxidized forms. It is a substance that can exist stably, and indicates a substance that can reversibly proceed from a reduction reaction from an oxidant to a reductant and from a reductant to an oxidant.

  In addition to the above, when the electrode to be formed is an electrode used for a primary battery and a secondary battery, the “active material” is an occlusion or release of metal ions involved in the electrode reaction (intercalation / desorption). It may be a material that can be intercalated or doped / undoped. Examples of this material include carbon materials used for anodes and / or cathodes of lithium ion secondary batteries, metal oxides (including composite metal oxides), and the like.

  In addition, in the case where the electrode to be formed is an electrode used for an electrolytic cell or an electrode used for a capacitor (capacitor), the “active material” means a metal (including a metal alloy) having electronic conductivity. Represents a metal oxide or a carbon material.

  In the present invention, the “electrolyte” in the electrochemical device is (1) a porous separator formed of an insulating material, in which an electrolyte solution (or a gelling agent is added to the electrolyte solution). (2) a solid electrolyte membrane (a membrane made of a solid polymer electrolyte or a membrane containing an ion conductive inorganic material), (3) a gelling agent in the electrolyte solution The layer which consists of a gel-like electrolyte obtained by adding (4) The layer which consists of electrolyte solution is shown.

  ADVANTAGE OF THE INVENTION According to this invention, the electrode which can fully reduce the contact resistance of the particle | grains containing an active material, and an electrical power collector, the electrochemical device provided with the same, and the manufacturing method of this electrode can be provided.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the following description, the same or corresponding parts are denoted by the same reference numerals, and redundant description is omitted.

(anode)
First, FIG. 1 shows a preferred embodiment of an anode 2 as an electrode for a lithium ion secondary battery according to the present invention. As shown in FIG. 1, the anode 2 has a plate-like (film-like) current collector 22 and an active material-containing layer 24 formed on the current collector 22. The shape of the anode 2 is not particularly limited, and may be, for example, a thin film as illustrated.

(Anode current collector)
The current collector 22 may be a conductive plate material, and for example, a copper foil metal thin plate may be used.

(Anode active material-containing layer)
The active material-containing layer 24 mainly includes particles 25 containing the active material, conductive auxiliary agent particles 26, and a binder 27.

(Particles containing active material)
As the particles 25 containing an active material, known particles containing an active material for an electrochemical device can be used. Examples of the particles 25 containing an active material include graphite, non-graphitizable carbon, graphitizable carbon, low temperature, which can occlude / release lithium ions (intercalation / deintercalation, or doping / dedoping). Carbon materials such as calcined carbon, metals that can be combined with lithium such as Al, Si and Sn, amorphous compounds mainly composed of oxides such as SiO ₂ and SnO ₂ , lithium titanate (Li ₃ Ti ₅ And particles containing O ₁₂ ) and the like. The particles 25 containing the active material may be composed only of the active material or may contain components other than the active material.

  The average particle diameter of the particles 25 containing the active material is preferably 0.1 to 500 μm. If the particle diameter of the particles 25 containing the active material is less than 0.1 μm, the particles 25 containing the active material tend to aggregate and tend not to be uniformly dispersed in the active material-containing layer. On the other hand, when the diameter of the particle 25 containing the active material exceeds 500 μm, the diffusion resistance of the electrolyte or the like in the particle 25 containing the active material tends to increase. That is, when the diameter of the particle 25 containing the active material exceeds 500 μm, the ion diffusion resistance in the particle containing the active material tends to be large and the impedance tends to increase. A particularly preferable particle size is 0.1 to 50 μm.

(Binder)
The binder 27 bonds the particles 25 containing the active material to each other so that the particles 25 containing the active material are in contact with each other, and makes the particles 25 containing the active material and the current collector 22 contact each other. The particles 25 containing the active material and the current collector 22 are combined.

  The binder 27 may be made of any material as long as the above-described bonding is possible. For example, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetra Fluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), ethylene-tetrafluoroethylene copolymer (ETFE), polychlorotrifluoroethylene (PCTFE), ethylene-chlorotrifluoroethylene copolymer (ECTFE), polyfluorinated Fluorine resin such as vinyl (PVF) can be used.

  In addition to the above, as the binder 27, for example, vinylidene fluoride-hexafluoropropylene-based fluororubber (VDF-HFP-based fluororubber), vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene-based fluororubber (VDF- HFP-TFE fluorine rubber), vinylidene fluoride-pentafluoropropylene fluorine rubber (VDF-PFP fluorine rubber), vinylidene fluoride-pentafluoropropylene-tetrafluoroethylene fluorine rubber (VDF-PFP-TFE fluorine rubber) ), Vinylidene fluoride-perfluoromethyl vinyl ether-tetrafluoroethylene fluorine rubber (VDF-PFMVE-TFE fluorine rubber), vinylidene fluoride-chlorotrifluoroethylene fluorine The containing rubbers (VDF-CTFE-based fluorine rubber) vinylidene fluoride-based fluorine rubbers such as may be used.

  In addition to the above, as the binder 27, for example, polyethylene, polypropylene, polyethylene terephthalate, aromatic polyamide, cellulose, styrene / butadiene rubber, isoprene rubber, butadiene rubber, ethylene / propylene rubber, or the like may be used. Also, thermoplastic elastomeric polymers such as styrene / butadiene / styrene block copolymers, hydrogenated products thereof, styrene / ethylene / butadiene / styrene copolymers, styrene / isoprene / styrene block copolymers, and hydrogenated products thereof. May be used. Further, syndiotactic 1,2-polybutadiene, ethylene / vinyl acetate copolymer, propylene / α-olefin (carbon number 2 to 12) copolymer and the like may be used.

  Further, as the binder 27, an electron conductive conductive polymer or an ion conductive conductive polymer may be used. Examples of the electron conductive conductive polymer include polyacetylene. In this case, since the binder 27 also functions as the conductive auxiliary agent particles, the conductive auxiliary agent particles 26 need not be added.

As the ion-conductive conductive polymer, for example, those having ion conductivity such as lithium ion can be used. For example, polymer compounds (polyether-based polymer compounds such as polyethylene oxide and polypropylene oxide) A crosslinked polymer of a polyether compound, polyepichlorohydrin, polyphosphazene, polysiloxane, polyvinylpyrrolidone, polyvinylidene carbonate, polyacrylonitrile, etc.) monomers, LiClO ₄ , LiBF ₄ , LiPF ₆ , LiAsF ₆ , LiCl, LiBr, Examples include Li (CF ₃ SO ₂ ) ₂ N, LiN (C ₂ F ₅ SO ₂ ) ₂ lithium salt, or a composite of alkali metal salt mainly composed of lithium. Examples of the polymerization initiator used for the combination include a photopolymerization initiator or a thermal polymerization initiator that is compatible with the above-described monomer.

  The content of the binder 27 included in the active material-containing layer 24 is preferably 0.5 to 6% by mass based on the mass of the active material-containing layer 24. When the content of the binder 27 is less than 0.5% by mass, the amount of the binder 27 is too small, and the tendency that the strong active material-containing layer 24 cannot be formed increases. Moreover, when the content rate of the binder 27 exceeds 6 mass%, the quantity of the binder 27 which does not contribute to an electric capacity will increase, and the tendency for it to become difficult to obtain sufficient volume energy density will become large. In this case, particularly, when the electronic conductivity of the binder 27 is low, the electric resistance of the active material-containing layer 24 increases, and a tendency that a sufficient electric capacity cannot be obtained increases.

(Conductive aid particles)
The conductive auxiliary agent particles 26 are not particularly limited, and known conductive auxiliary agent particles may be used. For example, carbon blacks, carbon materials such as highly crystalline artificial graphite and natural graphite, metal fine powders such as copper, nickel, stainless steel and iron, mixtures of the above carbon materials and metal fine powders, conductive oxides such as ITO, etc. These powder materials are mentioned. The average particle diameter of the conductive assistant particles is smaller than the particles containing the active material, and is preferably about 1 nm to 500 nm.

  These conductive auxiliary agent particles 26 are contained in a large amount in the binder 27. The conductive auxiliary particles 26 are interposed between the particles 25 containing the active material or between the particles 25 containing the active material and the current collector 22, or a plurality of conductive auxiliary particles 26 are connected in series. Thus, a further conductive path is formed between them. This brings about an effect of further reducing the contact resistance between the particles 25 containing the active material in the active material containing layer 24 and the contact resistance between the particles 25 containing the active material and the current collector 22.

  Here, the content of the conductive auxiliary agent particles 26 included in the active material-containing layer 24 is preferably 0.5 to 6% by mass based on the total mass of the active material-containing layer 24. When the content of the conductive auxiliary agent particles 26 is less than 0.5% by mass, the amount of the conductive auxiliary agent particles 26 is too small, and a tendency that an appropriate conductive path cannot be formed in the active material containing layer 24 increases. Further, when the content of the conductive auxiliary agent particles 26 exceeds 6% by mass, the amount of the conductive auxiliary agent particles 26 that do not contribute to the electric capacity increases, and it becomes difficult to obtain a sufficient volume energy density. Becomes larger.

  Such an active material-containing layer 24 has a conductive path in which the particles 25 containing the active material are in direct contact with each other, and a conductive path in which the particles 25 containing the active material are in contact with each other via one or more conductive aid particles 26. And have a pass. Therefore, the particles 25 containing these active materials form a three-dimensional network structure that is electrically connected to each other without being isolated.

  In addition, the active material-containing layer 24 includes one or more conductive paths in which the active material-containing particles 25 and the current collector 22 are in direct contact, and the active material-containing particles 25 and the current collector 22. These conductive paths are in contact with each other through the conductive auxiliary particles 26, and the particles 25 containing the active material are electrically connected to the current collector through these conductive paths.

  In this embodiment, in particular, the particles 25 containing the active material are embedded in the surface of the current collector 22, and the surface of the current collector 22 follows the shape of the particles 25 containing the active material. It is depressed and forms a depressed portion 22a.

(Cathode)
Next, FIG. 2 shows a preferred embodiment of the cathode 3 as an electrode for a lithium ion secondary battery according to the present invention. The cathode 3 includes a plate-like current collector 32 and an active material containing layer 34 formed on the current collector 32.

(Cathode current collector)
As the current collector 32, a conductive plate material can be used, and for example, an aluminum foil can be used.

(Cathode active material-containing layer)
The active material-containing layer 34 mainly includes particles 35 containing active material, conductive auxiliary agent particles 36, and a binder 37.

(Particles containing active material)
The particles 35 containing the active material are not particularly limited, and particles containing a known battery active material can be used. The particles 35 containing the active material, for example, lithium cobaltate (LiCoO _2), lithium nickel oxide (LiNiO _2), lithium manganese spinel (LiMn ₂ O _4), and the general formula: LiNi _x Mn _y Co _z O ₂ (x + y + z = 1) composite metal oxide, lithium vanadium compound, V ₂ O ₅ , olivine-type LiMPO ₄ (where M represents Co, Ni, Mn or Fe), lithium titanate (( Examples thereof include particles containing Li ₃ Ti ₅ O ₁₂ ), etc. Of course, the particles 35 containing an active material may be composed of only an active material, or may contain other materials.

  The average particle size of the particles 35 containing the active material of the cathode 3 is preferably 0.1 to 500 μm. If the particle diameter of the particles 35 containing the active material is less than 0.1 μm, the particles 35 containing the active material tend to aggregate and tend not to be uniformly dispersed in the active material-containing layer. On the other hand, when the diameter of the particles 35 containing the active material exceeds 500 μm, the diffusion resistance of the electrolyte or the like in the particles 35 containing the active material tends to increase. That is, when the diameter of the particle 35 containing the active material exceeds 500 μm, the ion diffusion resistance in the particle containing the active material tends to be large and the impedance tends to increase. A particularly preferable particle size is 0.1 to 50 μm.

(Binders, conductive aid particles, etc.)
As the conductive auxiliary agent particles 36 and the binder 37, the same materials as the conductive auxiliary agent particles 26 and the binder 27 of the active material-containing layer of the anode 2 can be used in the same manner. The effects of the conductive auxiliary agent particles 36 and the binder 37 are the same as those of the anode 2. Furthermore, it is preferable that the content of each conductive auxiliary agent particle 36 included in the active material-containing layer 34 and the content of the binder 37 are the same as those of the anode 2.

Further, from the viewpoint of forming the contact interface between the particle 35 containing the active material and the electrolyte in a three-dimensional and sufficient size, the BET specific surface area of the particle 35 containing the active material is 0.1 to 10 m ^2. / G is preferable, and 0.1 to ⁵ m ² / g is more preferable.

  The active material-containing layer 34 includes a conductive path in which the particles 35 containing the active material are in direct contact with each other, and a conductive path in which the particles 35 containing the active material are in contact with each other via one or more conductive aid particles 36. The particles 35 containing these active materials form a three-dimensional network structure that is electrically isolated from each other without being isolated.

  In addition, the active material-containing layer 34 includes one or more conductive paths in which the active material-containing particles 35 and the current collector 32 are in direct contact, and the active material-containing particles 35 and the current collector 32. The conductive particles are in contact with each other via the conductive auxiliary particles 36, and the particles 35 containing the active material are electrically connected to the current collector 32 through these conductive paths.

  In this embodiment, in particular, the particles 35 containing the active material are embedded in the surface of the current collector 32, and the surface of the current collector 32 follows the shape of the particles 35 containing the active material. A recess 32a is formed in the recess.

  Next, the function and effect of the anode 2 and the cathode 3 will be described. In the anode 2 and the cathode 3, depressions 22 a and 32 a are formed on the surfaces of the current collectors 22 and 32 along the shapes of the particles 25 and 35 containing the active material, and the particles 25 containing the active material are formed. , 35 are partially fitted into the recesses 22a and 32a. Therefore, the anode 2 and the cathode 3 of the present embodiment have contact areas between the particles 25 and 35 containing the active material and the current collectors 22 and 32 as compared with the conventional anode 2 and the cathode 3 having no depression. Can be widened. Therefore, the contact resistance between the current collectors 22 and 32 and the particles 25 and 35 containing the active material is reduced. Thereby, the internal resistance of the electrochemical device using such anode 2 and cathode 3 can be reduced, and the output of the electrochemical device can be increased and the energy density can be improved.

(Electrochemical device)
Next, an example of the lithium ion secondary battery 1 as an electrochemical device using the above-described anode 2 and cathode 3 will be described.

  FIG. 3 is a schematic cross-sectional view showing the basic configuration of the lithium ion secondary battery 1 according to the present embodiment. The lithium ion secondary battery 1 mainly includes a unit cell 5 including an anode 2 and a cathode 3, and an electrolyte layer 4 disposed between the anode 2 and the cathode 3, and a case 7 for sealing the unit cell 5. It is composed of The anode 2 is connected to an anode of an external power source (both not shown) during charging and functions as a cathode. The cathode 3 is connected to a cathode (none of which is shown) of an external power source during charging and functions as an anode.

(Electrolyte layer)
The electrolyte layer 4 may be a layer made of an electrolytic solution, or a layer made of a solid electrolyte (ceramic solid electrolyte, solid polymer electrolyte). The separator and the electrolytic solution impregnated in the separator and / or Alternatively, it may be a layer made of a solid electrolyte.

The electrolytic solution is prepared by dissolving a lithium-containing electrolyte in a non-aqueous solvent. The lithium-containing electrolyte may be appropriately selected from, for example, LiClO ₄ , LiBF ₄ , LiPF _6, etc., and Li (CF ₃ SO ₂ ) ₂ N, Li (C ₂ F ₅ SO ₂ ) ₂ N, etc. Lithium imide salt, LiB (C ₂ O ₄ ) ₂ or the like can also be used. The non-aqueous solvent can be selected from, for example, ethers, ketones, carbonates and the like, and organic solvents exemplified in JP-A No. 63-121260, but in the present invention, carbonates are particularly used. Is preferred.

  Among carbonates, it is particularly preferable to use a mixed solvent in which ethylene carbonate is the main component and one or more other solvents are added. Usually, the mixing ratio is preferably ethylene carbonate: other solvent = 5 to 70:95 to 30 (volume ratio). Since ethylene carbonate has a high freezing point of 36.4 ° C and is solidified at room temperature, ethylene carbonate alone cannot be used as a battery electrolyte, but it can be mixed by adding one or more other solvents having a low freezing point. The freezing point of the solvent is lowered and it can be used.

  In this case, any other solvent may be used as long as it lowers the freezing point of ethylene carbonate. For example, diethyl carbonate, dimethyl carbonate, propylene carbonate, 1,2-dimethoxyethane, methyl ethyl carbonate, γ-butyrolactone, γ-valerolactone, γ-octanoic lactone, 1,2-diethoxyethane, 1,2-ethoxy Examples include methoxyethane, 1,2-dibutoxyethane, 1,3-dioxolane, tetrahydrofuran, 2-methyltetrahydrofuran, 4,4-dimethyl-1,3-dioxane, butylene carbonate, and methyl formate. By using a carbonaceous material as the active material of the anode and using the above mixed solvent, the battery capacity is remarkably improved, and the irreversible capacity ratio can be sufficiently lowered.

  Such an electrolytic solution is also impregnated in the pores of the active material containing layer 24 of the anode 2 and the pores of the active material containing layer 34 of the cathode 3.

  Examples of the solid polymer electrolyte include a conductive polymer having ionic conductivity.

The conductive polymer is not particularly limited as long as it has lithium ion conductivity. For example, a polymer compound (polyether polymer compound such as polyethylene oxide and polypropylene oxide, high cross-linked polymer compound) Molecules, polyepichlorohydrin, polyphosphazene, polysiloxane, polyvinylpyrrolidone, polyvinylidene carbonate, polyacrylonitrile, etc.) monomers, and LiClO ₄ , LiBF ₄ , LiPF ₆ , LiAsF ₆ , LiCl, LiBr, Li (CF ₃ SO ₂ ) Examples include a composite of a lithium salt such as ₂ N or LiN (C ₂ F ₅ SO ₂ ) ₂ or an alkali metal salt mainly composed of lithium. Examples of the polymerization initiator used for the combination include a photopolymerization initiator or a thermal polymerization initiator that is compatible with the above-described monomer.

Further, as the supporting salt constituting the polymer solid electrolyte, for example, LiClO ₄ , LiPF ₆ , LiBF ₄ , LiAsF ₆ , LiCF ₃ SO ₃ , LiCF ₃ CF ₂ SO ₃ , LiC (CF ₃ SO ₂ ) ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiN (CF ₃ CF ₂ SO ₂ ) ₂ , LiN (CF ₃ SO ₂ ) (C ₄ F ₉ SO ₂ ) and a salt such as LiN (CF ₃ CF ₂ CO) ₂ , or These mixtures are mentioned.

  When a solid electrolyte is used, a solid electrolyte is further added into the pores of the active material-containing layer 24 of the anode 2 and the pores of the active material-containing layer 34 of the cathode 3.

  When using a separator for the electrolyte layer 4, the constituent material is, for example, one or more of polyolefins such as polyethylene and polypropylene (in the case of two or more, there is a laminate of two or more layers). And polyesters such as polyethylene terephthalate, thermoplastic fluororesins such as ethylene-tetrafluoroethylene copolymer, and celluloses. The form of the sheet includes a microporous membrane film, a woven fabric, a non-woven fabric, etc. having an air permeability measured by the method specified in JIS-P8117 of about 5 to 2000 sec / 100 cc and a thickness of about 5 to 100 μm. A solid electrolyte monomer may be impregnated into a separator and cured to be polymerized. Moreover, you may use it, making the electrolyte solution mentioned above contain in a porous separator.

  The case 7 is not particularly limited as long as the unit cell 5 can be sealed. For example, a metal can, a resin case, a metal laminate film pack, or the like can be used.

  According to such a lithium ion secondary battery 1, as described above, the contact resistance between the current collectors 22 and 32 of the anode 2 and the cathode 3 and the active material containing layers 24 and 34 is low. The DC electric resistance (impedance) of the secondary battery 1 can be lowered. Therefore, the output of the lithium ion secondary battery 1 can be increased and the energy density can be improved.

(Production method)
Next, a preferred embodiment of the method for manufacturing the anode 2 and the cathode 3 according to the above embodiment will be described.

  In this embodiment, first, composite particles 250 for anode 2 formed by binding particles 25 containing an active material with a binder 27 containing conductive auxiliary agent particles 26, and particles 35 containing an active material, Composite particles 350 for cathodes formed by bonding with a binder 37 including conductive auxiliary agent particles 36 are respectively prepared. And the particle layer of the composite particle 250 and the particle layer of the composite particle 350 are laminated | stacked with respect to each electrical power collector, and these laminated bodies are hot-rolled after that.

  First, the granulation process for producing the composite particles 250 will be described. FIG. 4 shows a schematic cross-sectional view of the composite particles 250 and 350.

  The composite particle 250 is a relatively loose agglomerate in which particles 25 containing an active material are integrated by a binder 27 containing a large number of conductive aid particles 26. The binder 27 loosely bonds the particles 25 containing the active material. Therefore, in the composite particles 250, the particles 25 containing the active material and the conductive auxiliary agent particles 26 are well dispersed. The composite particles 350 are obtained by integrating the particles 35 containing an active material with a binder 37 including conductive auxiliary agent particles 36 and have the same structure as the composite particles 250.

  Such composite particles 250 are formed through, for example, the following granulation process. This granulation step will be described more specifically with reference to FIG.

  The granulation step includes a raw material solution preparation step for preparing a raw material solution containing a binder, conductive auxiliary agent particles and a solvent, a fluidized bed forming step for fluidizing the particles containing the active material in a fluidized tank, Spraying the raw material liquid onto the particles containing the active material, aggregating the particles containing these active materials together, and then removing the solvent from the raw material liquid to form composite particles, and .

  First, in the raw material liquid preparation step, a solvent capable of dissolving the binder is used, and the binder is dissolved in this solvent. Next, the conductive auxiliary agent particles are dispersed in the obtained solution to obtain a raw material liquid. In this raw material liquid preparation step, a solvent (dispersion medium) capable of dispersing the binder may be used. Here, the solvent capable of dissolving the binder is not particularly limited as long as the binder can be dissolved and the conductive auxiliary agent particles can be dispersed. For example, N-methyl-2-pyrrolidone, N, N-dimethylformamide or the like can be used.

  Next, in the fluidized bed forming step, as shown in FIG. 5, an air current is generated in the fluid tank 55, and the active material is contained by introducing particles 25 containing the active material into the air stream. The particles 25 are fluidized.

  Next, in the spray drying step, the liquid droplets 256 of the raw material liquid are sprayed in the fluid tank 55 so that the liquid droplets 256 of the raw material liquid are attached to the particles 25 containing the active material that has been fluidized and flowed simultaneously. The droplets 256 are dried in the tank 55. At this time, the particles 256 containing the active material are adhered and aggregated by the droplets 256 and integrated to form a predetermined aggregate, and the solvent is removed from the droplets 256 of the raw material liquid to obtain composite particles 250.

  More specifically, the fluid tank 55 is, for example, a container having a cylindrical shape, and warm air (or hot air) L5 is introduced from the outside to the bottom of the fluid tank 55 so that the active material is contained in the fluid tank 55. An opening 52 for convection of the contained particles 25 is provided. Further, the side surface of the fluidized tank 55 is provided with an opening 54 for allowing the droplets 256 of the raw material liquid to be sprayed to flow into the particles 25 containing the active material convected in the fluidized tank 55. ing. The droplets 256 of the raw material liquid containing the binder 27, the conductive assistant particles 26 and the solvent are sprayed on the particles 25 containing the active material convected in the fluidized tank 55.

  At this time, the solvent in the raw material liquid droplets 256 can be quickly removed by adjusting the temperature of the atmosphere in which the particles 25 containing the active material are placed, for example, by adjusting the temperature of hot air (or hot air). The active material is kept at a predetermined temperature (preferably a temperature not exceeding the melting point of the binder significantly from 50 ° C., more preferably, a temperature not lower than the melting point of the binder (eg, 200 ° C.)) The raw material liquid droplets formed on the surfaces of the contained particles 25 are dried almost simultaneously with the spraying of the raw material liquid droplets 256. Thereby, the composite particle 250 in which the particles 25 containing the active material are gently bonded by the binder 27 containing the conductive auxiliary agent particles 26 can be obtained.

  In addition, the quantity of the conductive support agent particle | grains 26 and the binder 27 which adhere to the particle | grains 25 containing an active material is a value of 100x (mass of conductive support agent particle | grains + mass of binder) / (mass of composite particle). When expressed, it is preferably 1 to 12% by mass, and more preferably 3 to 12% by mass.

  For the reasons described above, it is preferable to use particles having an active material containing particles 25 having a particle diameter of 0.1 to 500 μm.

  Although the composite particles 250 have been described here, the composite particles 350 can be manufactured in the same manner.

  Next, a preferred example of a method for forming the anode 2 using the composite particles 250 obtained in this manner will be described with reference to FIG. The cathode 3 can be manufactured in the same manner using the composite particles 350.

  Specifically, a particle layer stacking step of supplying the composite particles 250 to the current collector 22 and stacking the particle layer 210 including the composite particles 250, heating the particle layer 210, and collecting the current collector 22 and the particles A roll process in which the layer 210 is passed between rotating rolls and the particle layer 210 is hot-rolled.

  Such a process can be easily performed by, for example, a hot roll press apparatus 300 as shown in FIG.

  Specifically, in the hot roll press apparatus 300, the current collector 22 is stretched substantially horizontally between the feed roll 302 and the feed roll 304. Here, a conductive resin layer (binder layer) 22 b is formed in advance on the upper surface of the current collector 22. The conductive resin layer 22b can include a binder and conductive auxiliary particles that are melted by heating. Specifically, the conductive resin layer 22b preferably includes the binder 27 of the composite particles 250 and the conductive auxiliary particles 26.

  Subsequently, the composite particle 250 is supplied from the hopper 306 storing the composite particles 250 onto the conductive resin layer 22 b of the current collector 22, and the particle layer 210 is laminated on the current collector 22. Then, the current collector 22 on which the particle layer 210 is laminated is passed between a pair of heated rolls 312 and 314 that are heated and rotated.

  As a result, the binder 27 of the composite particle 250 is melted and the composite particle 250 is consolidated, and the active material containing layer 24 having the structure as described above is formed on the current collector 22. The active material-containing layer 24 has a single plate shape and is bonded to the current collector 22 by a binder 27 including conductive auxiliary agent particles 26.

  In particular, in the present embodiment, since the composite particles 250 are rolled by the heat rolls 312 and 314, the particles 25 containing the active material are strongly pressed against the surface of the current collector 22 and are entrapped into the current collector 22, thereby collecting the current collector. The surface of 22 will be depressed along the shape of the particles 25 containing the active material. Therefore, as described above, it is possible to easily manufacture an electrode having the depression 22a and having a low contact resistance between the particle 25 containing the active material and the current collector 22. Further, since the formation of the sheet-like active material-containing layer 24 and the adhesion of the active material-containing layer 24 and the current collector 22 can be performed simultaneously, the number of processes can be reduced and the cost can be reduced as compared with the conventional case. Become.

  Here, it is preferable that the surface temperature of the heat roll 312 and the heat roll 314 is 60-200 degreeC. Although depending on the melting temperature of the binder 27, if the temperature is about this level, the binder 27 suitably bonds the particles 25 containing the active material or the particles 25 containing the active material and the current collector 22. it can. When the temperature is lower than 60 ° C., the bondability tends to deteriorate. On the other hand, when the temperature is higher than 200 ° C., the melting point or the softening point of a commonly used binder is greatly exceeded, so that it is difficult to produce a strong sheet.

The linear pressure applied between the heat rolls 312 and 314 is preferably 200 × 10 ^{2 to} 2000 × 10 ² N / m (about 20 to 200 kgf / cm). Here, when the linear pressure of the roll is less than 200 × 10 ² N / m, the particles 25 containing the active material tend not to be sufficiently embedded in the current collector 22. On the other hand, when the linear pressure of the roll exceeds 2000 × 10 ² N / m, the active material-containing layer 24 tends to be excessively consolidated and it is difficult for the electrolyte to diffuse in the active material-containing layer 24. Therefore, in the range of 200 × 10 ^{2 to} 2000 × 10 ² N / m, the impedance of the electrochemical device can be particularly lowered.

  Further, since the composite particles 250 are used in the present embodiment, the active material-containing particles 25 and the conductive auxiliary agent particles 26 can be well dispersed in advance in the composite particles 250 and can be rolled. In the substance-containing layer 24, the dispersibility between the particles 25 containing the active material and the conductive auxiliary agent particles 26 can be sufficiently improved. Therefore, in the active material-containing layer 24, a very good three-dimensional network of electron conduction paths can be formed by the particles 25 containing the active material and the conductive auxiliary agent particles 26.

  In addition, when the conductive resin layer 22 b is formed in advance on the current collector 22, the adhesiveness between the active material-containing layer 24, that is, the particles 25 containing the active material, and the current collector 22 is extremely improved. Here, even if the resin layer 22b is present on the current collector 22 in advance, the particles 25 containing the active material penetrate through the resin layer 22b by the heat roll and sink into the current collector 22. And since this resin layer 22b is a conductive resin layer, the contact resistance between the particles 25 containing the active material and the current collector 22 can be made sufficiently low. Here, even if the resin layer 22b is not formed in advance on the current collector 22, it is possible to form an electrode that exhibits the effects of the present invention.

  Further, in the particle layer lamination step, in addition to the composite particles 250, at least one of non-integrated single particles, that is, particles 25 containing the active material, conductive auxiliary agent particles 26, and binders 27. May be further mixed to laminate the particle layer. Further, the present embodiment can be carried out even if a single particle that is not complexed, that is, a particle layer including the active material-containing particle 25, the conductive auxiliary agent particle 26, and the binder 27 is formed without using any composite particle 250. It is possible to form the electrode according to the form.

  Alternatively, the particle layer 210 may not be heated by a heated hot roll, but may be passed between non-heated rolls after the particle layer 210 is heated by an infrared lamp or the like.

  And the electrode manufactured in this way can be easily used as a desired electrochemical device by a well-known method.

  The preferred embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment.

  For example, in the above embodiment, the conductive auxiliary agent particles 26 are added to improve the electrical contact between the particles 25 containing the active material and / or the particles 25 containing the active material and the current collector 22. However, depending on the case where the binder 27 has electrical conductivity or the characteristics of the particles 25 containing the active material, the operation as an electrode is possible without adding the conductive assistant particles 26.

  In addition, the electrochemical device includes the electrode of the present embodiment on the anode and the cathode, respectively, but the electrode of the present embodiment may be included as at least one of the anode and the cathode.

  In addition, the electrochemical device has one unit cell 5, but a plurality of unit cells may be stacked. In this case, the unit cells may be connected in parallel or in series.

  In the above description of the embodiment of the electrochemical device, the lithium ion secondary battery has been described. For example, the electrochemical device of the present invention includes at least an anode, a cathode, and an electrolyte layer having ion conductivity. As long as it has a configuration in which the anode and the cathode are arranged to face each other with the electrolyte layer interposed therebetween, another secondary battery or a primary battery may be used. As the particles containing the active material of the active material-containing layer of the anode or the cathode, those used in the existing primary battery can be used in addition to the above-mentioned exemplified materials. The conductive auxiliary particles and the binder may be the same as those exemplified above.

Furthermore, the electrode of the present invention is not limited to an electrode for a battery. For example, the electrode is used in an electrolytic cell, an electrochemical capacitor (such as an electric double layer capacitor or an aluminum electrolytic capacitor), or an electrochemical sensor. May be. Further, the electrochemical device of the present invention is not limited to a battery, and may be, for example, an electrolytic cell, an electrochemical capacitor (such as an electric double layer capacitor or an aluminum electrolytic capacitor), or an electrochemical sensor. Good. For example, in the case of an electrode for an electric double layer capacitor, the particles containing the active material of the active material-containing layer of the anode or cathode include carbon materials having a high electric double layer capacity such as coconut shell activated carbon, pitch activated carbon, and phenol resin activated carbon. Can be used. Here, in the case of a double layer capacitor, the specific surface area of the particles containing the active material in both the cathode 3 and the anode 2 is preferably 500 to 3000 m ² / g.

  Further, for example, as an anode used for salt electrolysis, for example, an active material of an active material containing layer obtained by thermally decomposing ruthenium oxide (or a composite oxide of ruthenium oxide and other metal oxides) is contained. It may be used as particles.

  When the electrochemical device of the present invention is an electrochemical capacitor, the electrolyte solution is an aqueous electrolyte solution or non-aqueous electrolyte solution (an organic solvent is used) used in an electrochemical capacitor such as a known electric double layer capacitor. Both non-aqueous electrolyte solutions) can be used.

  Furthermore, the type of the non-aqueous electrolyte solution is not particularly limited, but is generally selected in consideration of the solubility, dissociation degree, and liquid viscosity of the solute, and is a non-aqueous electrolyte solution having a high conductivity and a wide potential window. It is desirable. Examples of the organic solvent include propylene carbonate, diethylene carbonate, and acetonitrile. Examples of the electrolyte include quaternary ammonium salts such as tetraethylammonium tetrafluoroborate (boron tetrafluoride tetraethylammonium). In this case, it is necessary to strictly manage the moisture content.

  When the secondary battery 1 is a metal lithium secondary battery, the anode (not shown) may be an electrode made of only metal lithium or a lithium alloy that also serves as a current collector. The lithium alloy is not particularly limited, and examples thereof include alloys such as Li—Al, LiSi, and LiSn (here, LiSi is also handled as an alloy). In this case, the cathode may be configured using composite particles 250 configured as described later.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated in more detail, this invention is not limited to these Examples at all.

(Example A1)
Here, first, an electrode for an electric double layer capacitor was prepared.

(1) Preparation of Composite Particles First, composite particles 250 used for manufacturing an active material-containing layer in each electrode for an electric double layer capacitor were prepared according to the following procedure. Here, the composite particles 250 were composed of a cathode or anode active material (90% by mass), conductive auxiliary agent particles (5% by mass), and a binder (5% by mass).

  As the active material (particles containing the active material) for the cathode and anode, activated carbon (average particle size: 15 μm) was used. Carbon black (acetylene black) was used as the conductive auxiliary agent particles. Furthermore, polyvinylidene fluoride (PVDF) was used as a binder.

  First, a “raw material solution” (3% by mass of carbon black, 2% by mass of polyvinylidene fluoride) was prepared by dispersing carbon black in a solution in which polyvinylidene fluoride was dissolved in N, N-dimethylformamide as a solvent.

  Next, an air flow consisting of air was generated in a container having the same configuration as that of the fluidized tank 55 shown in FIG. 5, and activated carbon particles were put into a fluidized bed. Next, the above-mentioned raw material liquid was sprayed onto particles of activated carbon that had been fluidized, and the solution was adhered to the surfaces of the particles to aggregate the activated carbons. Note that N, N-dimethylformamide was removed from the surface of the particles almost simultaneously with the spraying by maintaining a constant temperature in the atmosphere where the activated carbon particles were placed during the spraying. In this way, composite particles 250 (average particle size: 200 μm) in which activated carbon was bonded and integrated with polyvinylidene fluoride containing carbon black were obtained.

  The amounts of activated carbon, carbon black, and polyvinylidene fluoride used in the granulation treatment were adjusted so that the mass ratio of these components in the finally obtained composite particle 250 was the above value.

(2) Production of electrode Subsequently, an electrode (cathode, anode) was produced. First, a conductive resin layer (thickness: 5 μm) was formed on one surface of an aluminum foil (thickness: 20 μm) as a current collector. The conductive resin layer is a layer (carbon black: 30) containing the same conductive additive particles (carbon black) as those contained in the composite particles and the same binder (polyvinylidene fluoride) as contained in the composite particles. Mass%, polyvinylidene fluoride: 70 mass%).

Next, using a hot roll press machine having a configuration similar to that shown in FIG. 6, the previously produced composite particles are dispersed on the resin layer of the current collector 22, and the particle layer is laminated. The current collector on which the layers were laminated was rolled at a high temperature with a hot roll. The rolling conditions were a roll temperature of 180 ° C. and a linear pressure applied between the rolls (hereinafter referred to as roll linear pressure) of 700 × 10 ² N / m. In this way, a pair of electrodes (cathode, anode) having an active material-containing layer thickness of 150 μm, an active material carrying amount: 45.0 mg / cm ² , and a porosity: 25% by volume was obtained.

(3) an electric double Creating layer capacitors are opposed to the electrode so as to sandwich the cellulosic separator, TEMA ⁺ BF ₄ ^- (triethylmethylammonium tetrafluoroborate) 1.2 mol / polycarbonate solution separator and the active material containing the L The layer was impregnated and sealed in an aluminum laminate pack to obtain an electric double layer capacitor.

(Examples A2, A3)
Examples A2 and A3 were the same as Example A1 except that the roll linear pressure was 200 × 10 ² N / m and 2000 × 10 ² N / m.

(Example A4)
In Example A4, a lithium ion secondary battery was created. The same electrode as in Example A1 was used for the anode. On the other hand, the cathode was prepared using the following composite particles and the following current collector using the same hot roll processing as in Example A1.

The composite particles include LiCoO ₂ particles (average particle size 0.5 mm) as particles containing an active material, acetylene black (Denka black) as a conductive auxiliary agent particle, and polyvinylidene fluoride (PVDF) as a binder. And prepared in the same manner as in Example A1. The particle size of the composite particles was 200 μm. The composition ratio of the composite particles was particles containing active material (90% by mass), conductive auxiliary agent particles (7% by mass), and binder (3% by mass).

Further, the current collector was an aluminum foil (thickness: 20 μm), and a surface on which a conductive resin layer (thickness: 5 μm) containing 30% by mass of acetylene black and 70% by mass of polyvinylidene fluoride was used. . Further, a 1 mol / L LiBF ₄ solution was used as the electrolytic solution, and a mixture containing ethylene carbonate and propylene carbonate in a volume ratio of 70:30 was used as the solvent of the electrolytic solution.

(Comparative Example A1)
In Comparative Example A1, the composite particles were previously hot-rolled with a hot roll at 120 ° C. at a roll linear pressure of 700 × 10 ² N / m to form an active material-containing sheet, and then the active material-containing sheet was used as a current collector. Except for superposition and thermocompression bonding at 180 ° C. and 5 MPa, the procedure was the same as Example A1.

  The DC impedance of these electrochemical devices at 1 kHz is shown in FIG. Compared with the comparative example 1 which formed the sheet | seat of the active material content layer conventionally, and bonded this with the electrical power collector, the particle layer laminated | stacked on the electrical power collector like this invention is hot-rolled, and an active material content is contained. In Examples 1 to 4 in which the layers were formed, it was confirmed that the impedance of the battery or capacitor could be reduced.

(Example B1)
The composite particles are composed of activated carbon (90% by mass) having a particle size of 2 μm as particles containing active material, acetylene black (6% by mass) as conductive auxiliary particles and PVDF (4% by mass) as a binder. An electric double layer capacitor was prepared in the same manner as in Example A1, except that the composite particle size was 60 μm, the roll temperature in rolling was 120 ° C., and the active material loading of the active material-containing layer was 9.0 mg / cm ^2. Obtained.

(Examples B2 to B6)
Example B2 was the same as Example B1 except that the activated carbon had a particle size of 5 μm and the composite particles had a particle size of 120 μm. Example B3 was the same as Example B1 except that the activated carbon had a particle size of 15 μm and the composite particles had a particle size of 200 μm. Example B4 was the same as Example B1, except that the activated carbon particle size was 18 μm and the composite particle particle size was 300 μm. Example B5 was the same as Example B1 except that the activated carbon had a particle size of 22 μm and the composite particles had a particle size of 450 μm. Example B6 was the same as Example B1 except that the activated carbon particle size was 28 μm and the composite particle particle size was 580 μm.

(Examples B7 to B10)
Example B7 was the same as Example B3, except that the roll linear pressure during pressing was 150 × 10 ² N / m. Example B8 was the same as Example B3 except that the roll linear pressure during pressing was 250 × 10 ² N / m. Example B9 was the same as Example B3 except that the roll linear pressure during pressing was 1900 × 10 ² N / m. Example B10 was the same as Example B3 except that the roll linear pressure during pressing was 2200 × 10 ² N / m.

(Example B11)
Without forming composite particles, an uncomposited particle layer in which activated carbon as active material-containing particles, acetylene black as conductive aid particles, and PVDF as a binder are mixed is heated on the current collector. Except for rolling, the procedure was the same as Example B3.

(Example C1)
In Example C1, a lithium ion secondary battery was created. The same electrode as in Example B3 was used for the anode. On the other hand, a cathode was prepared by performing hot roll processing with a roll linear pressure of 700 × 10 ² N / m using the following composite particles and the following current collector in the same manner as in Example B3. The active material loading of the cathode was 45 mg / cm ² and the porosity was 28% by volume.

The composite particles are formed of LiCoO ₂ particles having an average particle diameter of 2 μm as particles containing an active material, acetylene black (Denka black) as a conductive auxiliary agent particle, and PVDF as a binder, and the constitution is 90 masses in order. %, 7% by mass, and 3% by mass, and the particle size of the composite particles was 60 μm.

Further, the current collector was an aluminum foil (thickness: 20 μm), and a surface on which a conductive resin layer (thickness: 5 μm) containing 30% by mass of acetylene black and 70% by mass of polyvinylidene fluoride was used. . Further, a 1 mol / L LiBF ₄ solution was used as the electrolytic solution, and a mixture containing ethylene carbonate and propylene carbonate in a volume ratio of 70:30 was used as the solvent of the electrolytic solution.

(Examples C2 to C5)
In Example C2, the cathode was the same as Example C1 except that the LiCoO ₂ particles had a particle size of 5 μm and the composite particles had a particle size of 180 μm. In Example C3, the cathode was the same as Example C1, except that the LiCoO ₂ particles had a particle size of 8 μm and the composite particles had a particle size of 250 μm. In Example C4, the cathode was the same as Example C1 except that the LiCoO ₂ particles had a particle size of 12 μm and the composite particles had a particle size of 300 μm. In Example C5, the cathode was the same as Example C1, except that the LiCoO ₂ particles had a particle size of 15 μm and the composite particles had a particle size of 420 μm.

(Examples C6 to C9)
In Example C6, the cathode was the same as Example C2 except that the roll linear pressure during pressing was 150 × 10 ² N / m. In Example C7, the cathode was the same as Example C2 except that the roll linear pressure during pressing was 250 × 10 ² N / m. In Example C8, the cathode was the same as Example C2 except that the roll linear pressure during pressing was 1800 × 10 ² N / m. In Example C9, the cathode was the same as Example C2 except that the roll linear pressure during pressing was 2200 × 10 ² N / m.

(Example C10)
For the cathode, an uncomposited particle layer in which activated carbon as active material-containing particles, acetylene black as a conductive auxiliary agent particle, and PVDF as a binder are mixed without forming composite particles is a current collector The same procedure as in Example C2 was performed except that the hot roll was performed.

In the electric double layer capacitors of Examples B1 to B11 and the lithium ion secondary batteries of Examples C1 to C10, the impedance is sufficiently low, for example, at a relatively low roll linear pressure of about 700 × 10 ² N / m ( (Refer FIG. 8, FIG. 9). A suitable roll linear pressure is 200 to 2000 × 10 ² N / m. Moreover, when the particle diameter of the particle | grains containing an active material becomes large, there exists a tendency for impedance to become large.

  Furthermore, when the composite particles were formed, the impedance tended to be lower than when the composite particles were not formed.

It is a cross-sectional schematic diagram of the anode which concerns on embodiment of this invention. It is a cross-sectional schematic diagram of the cathode which concerns on embodiment of this invention. It is a cross-sectional schematic diagram which shows the electrochemical device using the anode of FIG. 1, and the cathode of FIG. It is a cross-sectional schematic diagram of the composite particle used when manufacturing an electrode. It is explanatory drawing which shows an example of the granulation process which manufactures composite particle. It is explanatory drawing which shows an example of the roll process at the time of manufacturing an electrode. It is a table | surface which shows the impedance of the electrochemical device in Example A1-A4 and Comparative Example A1. It is a table | surface which shows the impedance of the electrochemical device in Example B1-B11. It is a table | surface which shows the impedance of the electrochemical device in Example C1-C10.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Battery (electrochemical device), 2 ... Anode (electrode), 3 ... Cathode (electrode), 4 ... Electrolyte layer, 5 ... Unit cell, 22, 32 ... Active material containing layer, 22a, 32a ... Depression part, 22b ... resin layer, 24, 34 ... current collector, 25, 35 ... particles containing active material, 26, 36 ... conductive auxiliary agent particles, 27, 37 ... binder, 52 ... opening, 54 ... opening, 55 ... Fluidized tank, 250, 350 ... Composite particles, 256 ... Raw material liquid droplets, 210 ... Particle layer, 312, 314 ... Heat roll.

Claims (11)

A plate-like current collector, and an active material-containing layer provided on the current collector,
The active material-containing layer includes a plurality of particles containing an active material, and a binder that bonds particles containing the active material and the current collector together with the particles containing the active material. The surface of the current collector is an electrode recessed along the shape of the particles containing the active material.   The electrode according to claim 1, wherein in the active material-containing layer, conductive auxiliary agent particles are contained in the binder.   3. The electrode according to claim 1, wherein a particle size of the particles containing the active material in the active material-containing layer is 0.1 to 500 μm. A pair of electrodes, and an electrolyte interposed between the electrodes,
At least one of the pair of electrodes is
A plate-like current collector, and an active material-containing layer provided on the current collector,
The active material-containing layer includes a plurality of particles containing an active material, and a binder that bonds the particles containing the active material and the current collector together with the particles containing the active material. An electrochemical device in which the surface of the current collector is recessed along the shape of the particles containing the active material. A particle layer laminating step of laminating a particle layer containing a plurality of particles containing a binder and an active material, which is melted by heating, on a plate-shaped current collector,
The particle layer is heated, and the current collector and the particle layer are passed between rotating rolls to roll the particle layer, and the particles containing the active material are bonded to each other by the binder and the active layer is rolled. A roll process for bonding particles containing a substance and the current collector with the binder, and a method for producing an electrode.   The method for producing an electrode according to claim 5, wherein in the particle layer stacking step, the particle layer further contains conductive auxiliary particles.   The electrode according to claim 6, wherein, in the particle layer stacking step, the particle layer includes a plurality of composite particles obtained by previously integrating particles containing the active material with the binder including the conductive auxiliary agent particles. Production method.   The method for producing an electrode according to claim 5, wherein the roll step is performed by passing the current collector and the particle layer between heated rolls. The method for producing an electrode according to any one of claims 5 to 8, wherein a linear pressure applied between the rolls in the roll step is 200 × 10 ^{2 to} 2000 × 10 ² N / m.   6. In the particle layer laminating step, a binder layer that contains conductive assistant particles and is melted by heating is provided in advance on the surface of the current collector, and the particle layer is laminated on the binder layer. The manufacturing method of the electrode as described in any one of -9. The method for producing an electrode according to any one of claims 5 to 10, wherein a particle diameter of the particles containing the active material is 0.1 to 500 µm.

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