JP2009212113A - Method of manufacturing sheet for electrochemical device electrode - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of efficiently manufacturing an electrochemical device electrode sheet having high capacity and low resistance in large quantity by a collector made of a metal fiber sheet. <P>SOLUTION: The metal fiber sheet is used as the collector, thus replenishing an electrolyte to an electrode layer from both of a separator side and a collector side in the manufacture of a cell, and restraining resistance to a low level even if an electrode thickness is increased. As a result, the ratio of an electrode sheet in the cell is increased, and hence the capacity of the cell is increased and resistance is reduced. The electrode sheet is efficiently manufactured in large quantity with the metal fiber sheet as the collector by performing dry forming to powder made of an electrode material of an electrochemical device electrode. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a lithium ion secondary battery, an electric double layer capacitor in which both positive and negative electrodes are polarizable electrodes using activated carbon, or a positive electrode and a lithium ion made of a substance capable of reversibly supporting lithium ions and / or anions. High-capacity, low-resistance electrochemical device electrode (suitable for use in electrochemical devices such as hybrid capacitors composed of negative electrodes made of materials capable of reversibly supporting lithium ions or secondary batteries using lithium ion doping ( In the present specification, it may be simply referred to as an “electrode”).

  Electrochemical elements such as lithium ion secondary batteries and electric double layer capacitors that are small and light, have high energy density, and can be repeatedly charged and discharged are rapidly expanding their demands by utilizing their characteristics. Lithium ion secondary batteries are used in fields such as mobile phones and notebook personal computers because of their relatively high energy density, and electric double layer capacitors are used as memory backup compact power sources for personal computers and the like. Furthermore, recently, electric double layer capacitors are excellent in rapid charge / discharge characteristics, so that they have been used in construction machines such as excavators and cranes that require repeated charge / discharge. On the other hand, the energy density of the electric double layer capacitor is about 3 to 4 Wh / L, which is about two orders of magnitude smaller than that of the lithium ion secondary battery, aiming to achieve both high energy density and charge / discharge speed. Among the electrodes, hybrid capacitors using a Faraday reaction electrode on one side and a non-Faraday reaction electrode on the other side have been developed. With the expansion and development of applications, these electrochemical devices are required to have further improved characteristics such as low resistance and high capacity. On the other hand, cost reduction is also an important issue for market expansion, and proposals for inexpensive electrode manufacturing methods are also expected.

Lithium ion secondary batteries have high energy density, but there are still problems with output density, cycle characteristics, and safety. To improve output density, ion diffusion can be achieved by reducing electrode thickness or increasing electrode porosity. To reduce the resistance. However, in the method of thinning the electrode, the usage ratio of a member such as a separator or a current collector that does not contribute to the capacity increases, the ratio of the electrode to the cell decreases, and the energy density decreases. As a result, the cost per capacity is reduced. It has the problem of becoming higher. In addition, the porous electrode has a problem that the energy density is lowered and the cost is increased because the filling amount of the active material in the cell is reduced.
Further, the power density is improved by reducing the particle diameter of the active material. However, an electrode of a lithium ion secondary battery is manufactured by applying an electrode slurry containing an active material on a current collector. However, if the particle size of the active material is reduced, the fluidity of the slurry is deteriorated or the slurry concentration is lowered. However, since the coating speed cannot be increased, there is a problem that the manufacturing cost of the electrode sheet increases.

Electric double layer capacitors have high output density but low energy density, and new carbon materials aimed at higher capacity have been developed. For example, the proposal of the alkali activated charcoal using potassium (patent document 1) and the electric field activation process are proposed (patent document 2).
However, these proposals still have problems in practical use due to the deterioration of cycle characteristics. In addition, there are proposals to use a current collector having protrusions to increase the energy density of the electric double layer capacitor (Patent Document 3), or to fill the current collector with an active material using a metal fiber current collector ( Patent Documents 4 and 5).
In these proposals, even if the electrode thickness is increased, the current collector is enhanced by the current collector in the electrode, so that it is possible to obtain an electrode with a high output density and the ratio of the active material in the cell can be increased. The density can be increased. However, these proposals have the effect of lowering the electron resistance by arranging a current collector made of metal in the polarizable electrode, but cannot exhibit the effect of lowering the ion diffusion resistance. Therefore, although there is a certain effect, there is a limit to the decrease in resistance when used with high-speed charging / discharging. In addition, there is a problem in terms of productivity because the current collector is filled with an electrode material.
Furthermore, a proposal is made to fill the stainless steel fibers with activated carbon, and the stainless steel fibers that do not permeate activated carbon are used as a current collector to prevent the activated carbon from falling off (Patent Document 6), and the activated carbon layer formed into a sheet and a metal current collector. There is also a proposal (Patent Document 7) in which a fibrous current collector such as a stainless fiber is disposed in the middle of the plate. However, the current collector made of stainless steel sandwiching the polarizable electrode proposed in Patent Document 6 is considered to be thinner if it is thin for the purpose of preventing the activated carbon from falling off, and is different from the present invention. Therefore, nothing is mentioned about the porosity of the stainless fiber used as the current collector. On the other hand, the structure used in the proposal of Patent Document 7 is different from that of the present invention. Moreover, nothing is mentioned about the porosity of the fibrous current collector.
Further, in the examples described in Patent Document 6 and Patent Document 7, the thickness of the polarizable electrode is thick and a proposal aimed at increasing the capacity of the memory backup application or the like, and the current collector has a function of improving the ion diffusion resistance. This is different from the present invention which lowers the resistance. In addition, problems remain in productivity due to structural problems.

On the other hand, hybrid capacitors using a Faraday reaction electrode on one side and a non-Faraday reaction electrode on the other side are attracting attention, aiming to achieve both high energy density and charge / discharge speed. The feasibility has been enhanced by the proposal of a current collector in which a hybrid capacitor doped with lithium ions in advance and using activated carbon as a positive electrode has a through hole. (Patent Document 8)
However, there is a problem that it is difficult to form an electrode on a current collector having a through-hole and productivity is low (Patent Document 9).

JP 2004-47613 A JP 2002-25867 A JP-A-10-284349 Japanese Patent Laid-Open No. 9-232190 JP-A-6-196170 JP 60-161610 A Japanese Patent Laid-Open No. 2-16710 Japanese Patent No. 4015993 JP-A-2005-203116

  An object of the present invention is to provide a method for efficiently producing a high-capacity, low-resistance electrochemical element electrode sheet in large quantities using a current collector made of a metal fiber sheet.

As a result of intensive studies in view of the above problems, the present inventors have used a metal fiber sheet as a current collector to replenish the electrode layer with electrolyte from both the separator side and the current collector side when a cell is produced. It has been found that the resistance can be kept low even when the structure can be formed and the electrode thickness is increased. As a result, it was found that the ratio of the electrode sheet to the cell can be increased, so that the capacity of the cell can be improved and the resistance can be reduced.
Furthermore, it has been found that the electrode sheet can be efficiently produced in large quantities using a metal fiber sheet as a current collector by dry-molding a powder composed of an electrode material for an electrochemical element electrode, and the present invention is completed. It came.

Conventionally, when a slurry containing an electrode active component is applied or immersed in a porous current collector such as expanded metal or punched metal, a die coater or the like is required due to the large diameter of the through hole. In some cases, an undercoat was required. Further, since the coating is usually performed while pulling up in the vertical direction, the productivity is low due to a problem in strength. Further, in the metal fiber sheet, the slurry-like material containing the electrode active component can be easily supported on the current collector by controlling the diameter and porosity of the metal fiber, and it is not always necessary to undercoat or vertically It has also been found that the productivity of the electrode is improved compared to the above because no direction coating is required.
However, the inventors have found that an electrochemical device can be produced with higher productivity by applying the dry molding method proposed by the present inventors (Japanese Patent Laid-Open No. 2007-5747), and the present invention has been completed.

  Furthermore, porous or nonporous sheet metal bodies such as expanded metal and punched metal have been used as current collectors for electrochemical element electrodes. There are also proposals for using a current collector having a protrusion or filling a current collector with an active material using a porous metal current collector. However, according to the research of the present inventors, when a porous or non-porous sheet metal such as expanded metal or punched metal is used, the resistance increases with the thickness of the electrode layer. Further, it was found that the resistance increases when the density of the electrode layer is increased even by using a current collector having protrusions or using a porous metal current collector to fill the current collector with an active material. This indicates that resistance generally consists of electron resistance and ion diffusion resistance, and it is not possible to expect a sufficient reduction in resistance simply by using a current collector with protrusions or a porous metal current collector. Yes. The present inventors pay attention to ion diffusion resistance, and form an electrode layer on one side or both sides of the current collector using a metal fiber sheet as a current collector and at least a part of the current collector is not filled with the electrode constituent material. Thus, it was found that an electrode sheet capable of achieving both high capacity and low resistance can be obtained by supplying the electrolyte from both surfaces of the electrode layer.

Thus, the present invention is characterized by having the following gist.
(1) A method for producing a sheet for an electrochemical element electrode, comprising supplying a powder made of an electrode material for an electrochemical element electrode onto a current collector made of a metal fiber sheet and molding the powder.
(2) The method for producing a sheet for an electrochemical element electrode according to (1), wherein the current collector made of the metal fiber sheet has a thickness of 10 to 200 μm.
(3) The total thickness of the electrode layer and the current collector formed on the current collector made of the metal fiber sheet is 50 to 1000 μm, and (the total thickness of the electrode layer and the current collector) / (current collection) (Thickness of electric body) = 1-20
(1) The manufacturing method of the sheet | seat for electrochemical element electrodes of (2) characterized by the above-mentioned.
(4) The powder supplied onto the current collector made of metal fibers is formed by combining composite particles formed by binding an electrode active material and a conductive material with a binder. (1) The manufacturing method of the sheet | seat for electrodes for electrochemical elements as described in (2).
(5) The composite particles according to (4) are obtained in a step of obtaining a slurry containing an electrode active material, a conductive material, a binder and a dispersant, and in a step of spray-drying the slurry and performing spray granulation. The manufacturing method of the sheet | seat for electrochemical element electrodes as described in (1)-(4) characterized by the above-mentioned.
(6) The method for producing an electrochemical element electrode sheet according to any one of (1) to (5), wherein the metal fiber is made of stainless steel, aluminum, nickel, copper, gold, platinum, titanium, or other alloy. .
(7) The method for producing an electrochemical element electrode sheet according to any one of (1) to (6), wherein the metal fiber surface is coated with a metal having a resistivity lower than that of the metal fiber.
(8) The metal fibers are obtained by forming a sheet of a metal fiber having a fiber diameter of 2 to 20 μm and a fiber length of 1 to 12 mm and a binder fiber by a wet papermaking method (1) to (6) The manufacturing method of the sheet | seat for electrochemical element electrodes of description.
(9) Slurries composed of metal fibers having a fiber diameter of 2 to 20 μm and a fiber length of 1 to 12 mm and a binder fiber are formed into a sheet by a wet papermaking method, and the sheet is sintered between fibers in a hydrogen gas atmosphere. The manufacturing method of the sheet | seat for electrochemical element electrodes as described in (1)-(6) characterized by performing.
(10) A slurry comprising metal fibers having a fiber diameter of 2 to 20 μm and a fiber length of 1 to 12 mm and a binder fiber is formed into a sheet by a wet papermaking method, and the sheet is sintered between fibers in a hydrogen gas atmosphere. The method for producing a sheet for an electrochemical element electrode according to any one of (1) to (6), wherein the sintered sheet is coated with a metal having a lower resistivity than the metal fiber.

  According to the method for producing an electrode sheet by dry molding of the present invention, using an electrochemical element electrode current collector made of a metal fiber sheet, the electrode layer is replenished with electrolyte from both the separator side and the current collector side, By reducing the ion diffusion resistance, a large amount of electrochemical element electrode sheets having high energy density and low internal resistance can be efficiently provided.

As a method of forming an electrode layer on a current collector made of a metal fiber sheet, a mixture of electrode layer forming materials is formed into particles (hereinafter sometimes referred to as composite particles) and formed into a sheet by dry molding. It is possible to use a method in which the current collector is pressed or a composite particle is supplied onto a current collector made of a metal fiber sheet and dry-molded.
The composite particles have a weight average particle diameter of usually 0.1 to 1000 μm, preferably 5 to 500 μm, more preferably 10 to 100 μm.

  The composite particles used in dry molding are not particularly limited depending on the production method, and are spray drying granulation method, rolling bed granulation method, compression granulation method, stirring granulation method, extrusion granulation method, crushing granulation method. Known granulation methods such as a granulation method, a fluidized bed granulation method, a fluidized bed multifunctional granulation method, and a melt granulation method may be mentioned. Among them, the spray-drying granulation method, the rolling bed granulation method and the stirring type granulation method are preferable because spherical particles with high uniformity can be obtained, and the spray-drying granulation method is particularly preferable.

  The spray-drying granulation method includes a step of mixing an electrode active material, a binder, and other components as necessary in a solvent to form a dispersion, and spray-drying the dispersion to form composite particles Forming a step. Specifically, in the composite particle forming step, the dispersion is sprayed from an atomizer using a spray dryer, and the sprayed dispersion is dried inside a drying tower, so that it is contained in the dispersion. Spherical composite particles composed of an electrode active material, a binder, and other components are formed.

  The solvent used for obtaining the dispersion is not particularly limited, but when the above-described soluble resin is used, a solvent capable of dissolving the soluble resin is preferably used. Specifically, water is usually used, but an organic solvent can also 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; diethylformamide, dimethylacetamide and N-methyl- Examples include amides such as 2-pyrrolidone and dimethylimidazolidinone; sulfur solvents such as dimethyl sulfoxide and sulfolane; and alcohols are preferable.

  As a molding method for molding the composite particles into a sheet, a pressure molding method is preferable. The pressure forming method is a method of forming an electrode layer by applying pressure to the composite particles to perform densification by rearrangement and deformation of the electrode layer forming material. As the pressure molding, for example, as shown in FIG. 1, a roll pressure molding method in which composite particles are supplied to a roll-type pressure molding device with a supply device such as a screw feeder and an electrode layer is molded, or composite particles are Sprinkle on the current collector, adjust the thickness of the composite particles with a blade, etc., adjust the thickness, and then form with a pressurizing device, fill the mold with the composite particles, press the mold, etc. There is. Of these pressure moldings, roll pressure molding is preferred.

  The temperature at the time of molding is usually 0 to 200 ° C., preferably higher than the melting point or glass transition temperature of the binder, and more preferably 20 ° C. higher than the melting point or glass transition temperature. In roll press molding, the molding speed is usually 0.1 to 30 m / min, preferably 5 to 20 m / min. The pressing linear pressure between rolls is usually 0.2 to 30 kN / cm, preferably 0.5 to 10 kN / cm.

  The obtained electrode layer and the current collector made of the metal fiber sheet of the present invention are laminated to obtain an electrochemical element electrode. In addition, when the electrode layer is formed by roll pressing, the electrode layer is formed directly on the current collector made of the metal fiber sheet by feeding the current collector made of the metal fiber sheet to the roll simultaneously with the supply of the composite particles. You may laminate.

  In order to eliminate variations in electrode thickness and increase the density of the active material layer to increase the capacity, post-pressurization may be further performed as necessary. The post-pressing method is generally a press process using a roll. In the roll press process, two cylindrical rolls are arranged in parallel at a narrow interval in the vertical direction, and each is rotated in the opposite direction. The temperature of the roll may be adjusted by heating or cooling.

  By producing an electrochemical element electrode sheet by dry molding using a current collector made of metal fibers used in the present invention, it is possible to achieve a high capacity and low resistance of the electrochemical element electrode sheet. The reason why such a characteristic is obtained is estimated as follows.

  Since the electrode active material generally has low conductivity, a metal foil having high conductivity or a metal sheet (foil) having a through-hole such as expanded metal or punching metal is used as a current collector, and the electrode active material is formed thereon. The resistance is lowered by thinly coating the substance. When the electrode active material is applied thickly, the resistance increases as the electrode thickness increases. For this reason, it has been studied to improve the current collecting property of the electrode layer by using a current collector with protrusions or filling a current collector with a porous metal current collector. An increase in resistance is inevitable. Therefore, it is necessary to lower the ion diffusion resistance by lowering the electrode density, but the cell capacity is lowered. In the present invention, an electrode layer is formed on one side or both sides of a current collector made of a metal fiber sheet, but at least a part of the current collector is used in a porous state. Unlike the current collector having independent holes such as expanded metal and punching metal, the current collector made of the metal fiber sheet has a structure in which the holes are connected to each other. Therefore, the electrochemical element electrode sheet of the present invention was used. In the cell, the electrolyte can enter the porous structure of the current collector. As a result, in the electrochemical cell produced by the electrochemical element electrode sheet using the current collector of the present invention, the electrolyte solution is replenished from both the separator side and the current collector side, so that the ion diffusion resistance is lowered. Thus, an electrochemical element electrode sheet having high energy density and low internal resistance even when the electrode layer thickness is increased is provided.

  Furthermore, the composite particles made of the electrode material of the electrochemical element electrode are dry-molded, whereby the electrode layer itself formed on the metal fiber sheet can also hold an appropriate gap. As a result, the ion diffusion resistance of the electrochemical element electrode sheet can be kept low. It seems that a high-capacity, low-resistance electrochemical element electrode sheet can be efficiently produced in large quantities by a combination of the effect using the metal fiber sheet and the effect based on the structure of the electrode layer based on the forming method.

  The metal fiber sheet may be any metal as long as it is conductive and capable of fine wire processing, such as stainless steel, aluminum, nickel, copper, gold, platinum, titanium, and other alloys, and is limited to the type of metal. It is not a thing. Although depending on the type of electrochemical element, from the viewpoint of not impairing electrochemical stability, stainless steel and aluminum are preferable for the positive electrode, and copper, nickel and stainless steel are preferable for the negative electrode. Moreover, what coated the metal fiber surface with the metal which has a resistivity lower than the metal fiber can also be used.

  The metal fiber surface can be coated by a known method such as an electrolytic plating method, an electroless plating method, a sputtering method, a vapor deposition method, a plasma spraying method, or the like. Further, by sintering together with other low-resistance metal fibers having a melting point lower than that of the metal fibers, the surface of the metal fibers may be coated with a low-resistance metal simultaneously with the sintering.

Metal fibers are manufactured at low cost by blowing molten metal from a fine hole into an inert atmosphere by centrifugation. Further, a fibrous metal having a large aspect ratio obtained by cutting a metal wire produced using a die, chatter vibration or grinding of a lathe may be used as a raw material of the sheet. The metal fiber preferably has a fiber diameter of 2 to 20 μm and a fiber length of 1 to 120 mm. If the fiber diameter is thinner than 2 μm, the sheet strength is insufficient, which causes breakage when forming the electrode layer. If the fiber diameter is larger than 20 μm, the desired sheet thickness is difficult to obtain. In addition, the number of fibers is relatively reduced, and the contact point between the fibers is reduced, so that the resistance is increased.
On the other hand, if the fiber length is shorter than 1 mm, the sheet strength becomes weak. When the fiber length is longer than 120 mm, the sheet becomes unsatisfactory and it becomes difficult to form a smooth electrode layer.

As a method for producing a metal fiber sheet, a molten metal is blown out from a fine hole into an inert atmosphere by a centrifugal method to form a sheet, or a metal short fiber is made into a nonwoven fabric by a wet papermaking method. Further, the metal fiber can be made into a nonwoven fabric by a wet papermaking method together with a heat-melting binder, and then heat-fused to increase the density of the sheet or can be sintered and fused.
Furthermore, a thermosetting conductive adhesive may be applied or impregnated on at least one surface of the metal fiber sheet produced by the wet papermaking method.
In addition, it can be obtained by a method for producing a braid or woven fabric.
The thickness of the metal sheet is preferably 10 to 200 μm, preferably 15 to 150 μm, more preferably 20 to 100 μm. When the thickness of the metal sheet is less than 10 μm, the strength is low and the metal sheet is easily broken during molding. Further, when the thickness of the metal sheet is greater than 200 μm, the proportion of the current collector made of the metal sheet in the cell increases and the energy density decreases.

  The metal fiber sheet for a current collector used in the present invention can increase the density of the sheet, and the sheet thickness can be reduced to 10 to 100 μm, so that the metal short fiber is made into a nonwoven fabric by a wet papermaking method. Furthermore, after forming metal fibers into a non-woven fabric by a wet papermaking method together with a heat-meltable binder, the method of heat-sealing to increase the density of the sheet or sinter-bonding, and further, the metal fibers together with the heat-meltable binder to form a wet paper A non-woven fabric is preferably used, followed by heating and fusing to increase the density of the sheet, or sintering and fusing.

  Specifically, in the case of the wet papermaking method, one or more kinds of metal fibers cut into short fibers are disperse and dispersed in water, an appropriate amount of binder and an auxiliary agent are added as necessary, and mixed, It can be dehydrated on the wire to obtain a pressing step and a drying step to form a sheet. Further, the binder or the like can be thermally decomposed and removed by heating in a vacuum or a non-oxidizing atmosphere.

  As the binder, for example, polyvinyl alcohol fiber, polyethylene fiber, polypropylene fiber, cellulose pulp and the like can be used, and as an auxiliary agent, a dispersant, a surfactant, an antifoaming agent, etc. that are generally used in a wet papermaking method. Can be used. As the non-oxidizing atmosphere, argon gas, nitrogen gas, hydrogen gas, or the like can be used.

  Moreover, you may sinter metal fibers of a porous sheet. Sintering may be performed in a vacuum or in a non-oxidizing atmosphere at a temperature near the melting point of the metal fiber, for example, in the case of stainless steel fiber, at 120 ° C. for 1 to 2 hours.

  The porosity of the metal fiber is appropriately selected depending on the diameter of the metal fiber and the thickness of the fiber. Generally, when the porosity of the metal fiber sheet is lower than 30%, the sheet density increases and the amount of intrusion of the electrolytic solution increases. As a result, the effect of lowering the resistance when an electrochemical element is obtained is reduced. In addition, the sheet becomes hard. Further, when the porosity is higher than 95%, the number of fibers constituting the sheet is reduced, the strength of the sheet is reduced, or the contact between the metal fibers is reduced and the resistance is increased.

In the present invention, the porosity is a value indicating the degree of porosity of the sheet, and is represented by the following formula.
Porosity (%) = {1− (apparent density of sheet / true density of sheet)} × 100
In the formula, the apparent density of the sheet is a value calculated from the basis weight and thickness of the sheet. The true density of the sheet means the density of the fiber itself (including the coated metal).

  The current collector made of the metal fiber sheet of the present invention includes a lithium-containing composite metal oxide as a positive electrode, a lithium ion secondary battery made of a carbon material capable of intercalating lithium ions, and an electrode layer as activated carbon, conductive An electric double layer capacitor comprising a polarizable electrode composed of a binder, a binder, or a positive electrode comprising a substance capable of reversibly carrying lithium ions and / or anions and a substance capable of carrying lithium ions reversibly The present invention can be applied to a hybrid capacitor composed of a negative electrode and a secondary battery using lithium ion doping.

The material constituting the electrode layer is used to obtain an electrochemical element electrode. Specifically, it contains at least an electrode active material and a binder, and further contains a conductive material and a soluble resin as necessary. Etc.
The electrode active material is appropriately selected depending on the type of electrochemical element. As an electrode active material for a positive electrode of a lithium ion secondary battery, lithium-containing composite metal oxides such as LiCoO ₂ , LiNiO ₂ , LiMnO ₂ , LiMn ₂ O ₄ , LiFePO ₄ , LiFeVO ₄ ; TiS ₂ , TiS ₃ , non Transition metal sulfides such as crystalline MoS ₃ ; transition metal oxides such as Cu ₂ V ₂ O ₃ , amorphous V ₂ O · P ₂ O ₅ , MoO ₃ , V ₂ O ₅ , V ₆ O 1 ₃ ; Illustrated. Furthermore, conductive polymers such as polyacetylene and poly-p-phenylene are listed.

  Examples of the electrode active material for the negative electrode of the lithium ion secondary battery include carbonaceous materials such as amorphous carbon, graphite, natural graphite, mesocarbon microbeads (MCMB), and pitch-based carbon fibers; high conductivity such as polyacene Examples include molecules. These electrode active materials can be used individually or in combination of 2 or more types according to the kind of electrochemical element. When the electrode active materials are used in combination, two or more types of electrode active materials having different average particle sizes or particle size distributions may be used in combination.

The electrode active material used for the electrode of the lithium ion secondary battery is preferably sized into spherical particles. When the shape of the particles is spherical, a higher density electrode can be formed during electrode molding. A mixture of fine particles having a weight average particle diameter of about 1 μm and relatively large particles having a weight average particle diameter of 3 to 8 μm, or particles having a broad particle size distribution of 0.5 to 8 μm is preferable. Particles having a particle size of 50 μm or more are preferably used after being removed by sieving or the like. The tap density defined by ASTM D4164 of the electrode active material is not particularly limited, but those having a positive electrode of 2 g / cm ³ or more and those of a negative electrode of 0.6 g / cm ³ or more are preferably used.

As an electrode active material for an electric double layer capacitor, an allotrope of carbon is usually used. The electrode active material for an electric double layer capacitor is preferably one that can form an interface with a larger area even with the same weight, that is, one having a large specific surface area. Specifically, the specific surface area of ^{30 m} 2 / g or more, preferably preferably 500~5,000m ² / g, more preferably 1,000~3,000m ² / g. Specific examples of the allotrope of carbon include activated carbon, polyacene, carbon whisker, and graphite, and these powders or fibers can be used. A preferable electrode active material for the electric double layer capacitor is activated carbon, and specific examples include phenol-based, rayon-based, acrylic-based, pitch-based, and coconut shell-based activated carbon. These allotropes of carbon can be used singly or in combination of two or more as an electrode active material for electric double layer capacitors. When carbon allotropes are used in combination, two or more types of carbon allotropes having different average particle diameters or particle size distributions may be used in combination.

In addition, nonporous carbon having microcrystalline carbon similar to graphite and having an increased interlayer distance of the microcrystalline carbon can be used as the electrode active material. Such non-porous carbon is obtained by dry-distilling graphitized charcoal with microcrystals of a multilayer graphite structure at 700 to 850 ° C., then heat-treating with caustic at 800 to 900 ° C., and if necessary with heated steam. It is obtained by removing the residual alkali component.
When a powder having a weight average particle diameter of 0.1 to 100 μm, preferably 1 to 50 μm, more preferably 2 to 10 μm is used as an electrode active material for an electric double layer capacitor, the electric double layer capacitor electrode can be made thin. It is preferable because it is easy and the capacitance can be increased.

  The positive electrode active material of the hybrid capacitor is made of a material that can reversibly carry lithium ions and anions such as tetrafluoroborate. As such a positive electrode active material, various materials can be used, and activated carbon or a heat-treated product of an aromatic condensation polymer having a hydrogen atom / carbon atom ratio of 0.50 to 0.05. A polyacene organic semiconductor (PAS) having a skeleton structure is preferred.

  On the other hand, the negative electrode active material of the hybrid capacitor is formed of a material that can reversibly carry lithium ions. Preferred examples of the negative electrode active material include carbon materials such as graphite, non-graphitizable carbon, hard carbon, and coke, and polyacene-based materials (PAS) described as the positive electrode active material. These carbon materials and PAS are obtained by carbonizing a phenol resin or the like, activated as necessary, and then pulverized.

  Further, the conductive material used as the electrode layer forming material as necessary is made of an allotrope of particulate carbon having conductivity, and improves the conductivity of the electrochemical element electrode. The weight average particle diameter of the conductive material is preferably smaller than the weight average particle diameter of the electrode active material, and is usually in the range of 0.001 to 10 μm, preferably 0.05 to 5 μm, more preferably 0.01 to 1 μm. is there. When the particle size of the conductive material is within this range, high conductivity can be obtained with a smaller amount of use. Specific examples of the conductive material include conductive carbon black such as furnace black, acetylene black, and ketjen black (registered trademark of Akzo Nobel Chemicals Bethloten Fennaut Shap); graphite such as natural graphite and artificial graphite. . Among these, conductive carbon black is preferable, and acetylene black and furnace black are more preferable. These conductive materials can be used alone or in combination of two or more.

  The amount of the conductive material is usually 0.1 to 50 parts by weight, preferably 0.5 to 15 parts by weight, more preferably 1 to 10 parts by weight with respect to 100 parts by weight of the electrode active material. When an electrode having an amount of the conductive material within this range is used, the capacity of the electrochemical element can be increased and the internal resistance can be decreased.

  The binder used for forming the electrode layer is not particularly limited as long as it is a compound having a binding force, but a dispersion-type binder is preferable. The dispersion type binder is a binder having a property of being dispersed in a solvent, and examples thereof include polymer compounds such as a fluorine polymer, a diene polymer, an acrylate polymer, polyimide, polyamide, and polyurethane. More preferred are fluorine-based polymers, diene-based polymers, and acrylate-based polymers. These binders can be used alone or in combination of two or more.

  The fluorine-based polymer is a polymer containing a monomer unit containing a fluorine atom. The ratio of the monomer unit containing fluorine in the fluoropolymer is usually 50% by weight or more. Specific examples of the fluorine-based polymer include fluorine resins such as polytetrafluoroethylene and polyvinylidene fluoride, and polytetrafluoroethylene is preferable.

  The diene polymer is a homopolymer of a conjugated diene or a copolymer obtained by polymerizing a monomer mixture containing a conjugated diene, or a hydrogenated product thereof. The proportion of the conjugated diene in the monomer mixture is usually 40% by weight or more, preferably 50% by weight or more, more preferably 60% by weight or more. Specific examples of the diene polymer include conjugated diene homopolymers such as polybutadiene and polyisoprene; aromatic vinyl / conjugated diene copolymers such as carboxy-modified styrene / butadiene copolymer (SBR); Examples include vinyl cyanide / conjugated diene copolymers such as acrylonitrile / butadiene copolymer (NBR); hydrogenated SBR, hydrogenated NBR, and the like.

  The acrylate polymer is a copolymer obtained by polymerizing a homopolymer of acrylic acid ester and / or methacrylic acid ester or a monomer mixture containing them. The ratio of acrylic acid ester and / or methacrylic acid ester in the monomer mixture is usually 40% by weight or more, preferably 50% by weight or more, more preferably 60% by weight or more. Specific examples of the acrylate polymer include 2-ethylhexyl acrylate / methacrylic acid / acrylonitrile / ethylene glycol dimethacrylate copolymer, 2-ethylhexyl acrylate / methacrylic acid / methacrylonitrile / diethylene glycol dimethacrylate copolymer, acrylic Crosslinking of 2-ethylhexyl acid / styrene / methacrylic acid / ethylene glycol dimethacrylate copolymer, butyl acrylate / acrylonitrile / diethylene glycol dimethacrylate copolymer, and butyl acrylate / acrylic acid / trimethylolpropane trimethacrylate copolymer Type acrylate polymer; ethylene / methyl acrylate copolymer, ethylene / methyl methacrylate copolymer, ethylene / ethyl acrylate copolymer, and A copolymer of ethylene and acrylic acid (or methacrylic acid) such as an ethylene / ethyl methacrylate copolymer; a radical polymerizable monomer in the copolymer of ethylene and acrylic acid (or methacrylic acid) A graft polymer obtained by graft polymerization; and the like. In addition, as a radically polymerizable monomer used for the said graft polymer, methyl methacrylate, acrylonitrile, methacrylic acid etc. are mentioned, for example. In addition, ethylene / acrylic acid copolymers, ethylene / methacrylic acid copolymers, and the like can be used as binders.

  Among these, from the viewpoint that an active material layer excellent in binding property and surface smoothness with a current collector can be obtained, and an electrode for an electrochemical element having high capacitance and low internal resistance can be produced. Diene polymers and cross-linked acrylate polymers are preferred, and cross-linked acrylate polymers are particularly preferred.

  The binder is not particularly limited depending on its shape, but has good binding properties, and can be prevented from being deteriorated due to a decrease in the capacitance of the created electrode or repeated charge / discharge, so that it is particulate. Is preferred. Examples of the particulate binder include those in which particles of a dispersion-type binder such as latex are dispersed in water, and powders obtained by drying such a dispersion.

  Further, the binder may be particles having a core-shell structure obtained by polymerizing a mixture of two or more kinds of monomers stepwise. A binder having a core-shell structure is obtained by first polymerizing a monomer that gives the first-stage polymer to obtain seed particles, and in the presence of the seed particles, a single quantity that gives the second-stage polymer. It is preferable to manufacture by polymerizing the body.

  The ratio between the core and the shell of the binder having the core-shell structure is not particularly limited, but the core part: shell part is usually 50:50 to 99: 1, preferably 60:40 to 99: 1 by mass ratio. Preferably it is 70: 30-99: 1. The polymer compound constituting the core part and the shell part can be selected from the above polymer compounds. It is preferable that one of the core part and the shell part has a glass transition temperature of less than 0 ° C and the other has a glass transition temperature of 0 ° C or higher. Moreover, the difference of the glass transition temperature of a core part and a shell part is 20 degreeC or more normally, Preferably it is 50 degreeC or more.

  The particulate binder is not particularly limited depending on the number average particle diameter, but is usually 0.0001 to 100 μm, preferably 0.001 to 10 μm, more preferably 0.01 to 1 μm. It is what has. When the number average particle diameter of the binder is within this range, an excellent binding force can be imparted to the active material layer even when a small amount of the binder is used. Here, the number average particle diameter is a number average particle diameter calculated as an arithmetic average value obtained by measuring the diameter of 100 binder particles randomly selected in a transmission electron micrograph. The shape of the particles can be either spherical or irregular.

  The amount of the binder used is usually 0.1 to 50 parts by weight, preferably 0.5 to 20 parts by weight, and more preferably 1 to 10 parts by weight with respect to 100 parts by weight of the electrode active material. is there.

  In addition to the above, the electrode layer forming material preferably contains a soluble resin. The soluble resin is a resin that dissolves in a solvent, and is preferably used by dissolving in a solvent when preparing a dispersion described later, and has an action of uniformly dispersing an electrode active material, a conductive material, etc. in the solvent. Is. Soluble resins include cellulosic polymers such as carboxymethylcellulose, methylcellulose, ethylcellulose and hydroxypropylcellulose, and ammonium or alkali metal salts thereof; polyacrylic acid (or methacrylic acid) such as sodium polyacrylic acid (or methacrylic acid) ) Salt; polyvinyl alcohol, modified polyvinyl alcohol, polyethylene oxide; polyvinyl pyrrolidone, polycarboxylic acid, oxidized starch, phosphate starch, casein, various modified starches, chitin, chitosan derivatives and the like. These soluble resins can be used alone or in combination of two or more. Among these, a cellulose polymer is preferable, and carboxymethyl cellulose or an ammonium salt or an alkali metal salt thereof is particularly preferable. The use amount of the soluble resin is not particularly limited, but is usually 0.1 to 10 parts by weight, preferably 0.5 to 5 parts by weight, and more preferably 0.8 to 100 parts by weight of the electrode active material. It is in the range of 8 to 2 parts by weight.

  The electrode layer forming material may further contain other additives as necessary. Examples of other additives include a surfactant. Examples of the surfactant include amphoteric surfactants such as anionic, cationic, nonionic, and nonionic anions. Among them, anionic or nonionic surfactants that are easily thermally decomposed are preferable. The amount of the surfactant is not particularly limited, but is 0 to 50 parts by weight, preferably 0.1 to 10 parts by weight, more preferably 0.5 to 5 parts by weight with respect to 100 parts by weight of the electrode active material. It is a range.

Moreover, the relationship between the electrode layer formed on the current collector made of the metal fiber sheet and the thickness of the current collector must satisfy the following.
The total thickness of the electrode layer and the current collector is 50 to 1000 μm, and (the total thickness of the electrode layer and the current collector) / (thickness of the current collector) = 1 to 20.
When the ratio is smaller than 1, the ratio of the current collector to the cell increases, and the energy density of the cell decreases. On the other hand, when the ratio is greater than 20, the amount of ions supplied from the electrolytic solution to the electrode layer decreases, and the resistance increases.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further more concretely, this invention is not limited to these Examples. In the examples and comparative examples, “part” and “%” are based on weight unless otherwise specified.

First, it shows about the manufacturing method (1)-(4) of a metal fiber sheet used as a collector of this invention.
Example of Metal Fiber Sheet Manufacturing Method Example of Metal Fiber Sheet Manufacturing Method by Wet Papermaking Method 95 parts by weight of stainless steel fiber (material: SUS316L, trade name: Susmic, manufactured by Tokyo Steel Co., Ltd.) having a fiber diameter of 8 μm and a fiber length of 4 mm, and water A slurry consisting of 5 parts by weight of a polyvinyl alcohol fiber (trade name: Fibrybond VPB105-1, manufactured by Kuraray Co., Ltd.) having a melting temperature of 70 ° C. is made by a wet papermaking method, dehydrated and heated and dried to obtain a basis weight of 64 g / An m ² sheet was obtained. The obtained sheet was heat-pressed under the conditions of a linear pressure of 400 kg / cm and a speed of 5 m / min using a heating roll having a surface temperature of 160 ° C. to obtain a stainless steel fiber sheet having a thickness of 33 μm and a porosity of 72%. It was.

Example of metal fiber sintered sheet production method A sheet obtained by the wet papermaking method in the same manner as the metal fiber sheet described in (1) except for the basis weight of rice was brazed with a continuous sintering furnace (brazed with a mesh belt) in a hydrogen gas atmosphere. Furnace), a sintering process was performed at a heat treatment temperature of 1120 ° C. and a speed of 15 cm / min to obtain a sintered metal fiber sheet having a rice basis weight of 64 g / m ² , a thickness of 27 μm, and a porosity of 68%.

Example of manufacturing method of thermosetting conductive adhesive-treated metal fiber sheet (production of metal fiber sheet)
95 parts of stainless steel fiber (material: SUS316L, trade name: Susmic, manufactured by Tsuna Co., Ltd.) with a fiber diameter of 8 μm and a fiber length of 4 mm, and polyvinyl alcohol fiber as binding fiber (melting temperature in water: 70 ° C., trade name: fibril) bond VPB105-1, a slurry consisting of Kuraray Co., Ltd.) 5 parts by papermaking and subjected to wet papermaking machine and was dehydrated and dried to obtain a metal fiber sheet basis weight amount 62 g / m ^2.

(Production of thermosetting conductive adhesive film)
35 parts by weight of acrylonitrile-butadiene copolymer (NBR rubber) (NIPOL 1021, manufactured by Nippon Zeon Co., Ltd.) and 35 parts by weight of bisphenol A type resol phenol resin (CKM-908, manufactured by Showa Polymer Co., Ltd.) ), 30 parts by weight of Denka Black (manufactured by Denki Kagaku Co., Ltd.) was added to a mixed solvent of methyl ethyl ketone / toluene (weight ratio 70/30) so as to have a solid concentration of 10%, and dissolved and dispersed in a sand mill for 12 hours. A paint was made.

The obtained paint was filtered using a 25 μm diameter filter. The metal fiber sheet prepared above was sprayed onto the filtered paint so that the basis weight was 5 g / m ^2, and then roll press treatment was performed at a linear pressure of 50 kg / cm and a temperature of 100 ° C. Next, the solvent was removed by volatilization under a drying condition of 130 ° C. to obtain a semi-cured state (B stage).

In Examples and Comparative Examples, the type of metal fiber, the diameter of the metal fiber, and the length of the metal fiber were selected, and the method described above was selected to produce a metal fiber sheet.
The results are shown in Tables 1, 2 and 3.

  Next, the manufacturing method of the electrical double layer capacitor which used the metal fiber sheet produced above as a collector, and its characteristic evaluation result are shown.

Production of electrode for electric double layer capacitor (Example of production of electrode by dry molding)
(Production of composite particles used for electrode layer formation)
100 parts of an electrode active material (activated carbon with a specific surface area of 2000 m ² / g and a weight average particle diameter of 5 μm), 5 parts of a conductive material (acetylene black “Denka black powder”: manufactured by Denki Kagaku Kogyo Co., Ltd.), dispersive binder (number A 40% aqueous dispersion of a cross-linked acrylate polymer having an average particle size of 0.15 μm and a glass transition temperature of −40 ° C. “AD211” (manufactured by Nippon Zeon Co., Ltd.) in a solid content of 7.5 parts, a soluble resin (carboxymethylcellulose) Of 1.5% aqueous solution “DN-800H” (manufactured by Daicel Chemical Industries, Ltd.) in solid content and 231.8 parts of ion-exchanged water “TK homomixer” (manufactured by Tokushu Kika Kogyo Co., Ltd.) ) To obtain a slurry having a solid content of 25%. Next, the slurry was spray-dried with hot air at 150 ° C. using a spray dryer to obtain an electrode material as spherical composite particles having a weight average particle diameter of 50 μm. The weight average particle diameter of the composite particles was measured using a powder measuring device (Powder Tester PT-R: manufactured by Hosokawa Micron Corporation).
In all of the examples and comparative examples of the electric double layer capacitor, the composite particles prepared above were used.

(Preparation of electrode sheet)
The electrode was produced using the roll press machine as shown in FIG. 2 with the metal fiber sheet which uses the obtained composite particle as a collector. A metal fiber sheet used as a current collector as shown in 1 of FIG. 2 is supplied between press rolls, and composite particles are formed as shown in 2 of FIG. 2 using a powder supply device shown in 3 of FIG. Roll 2 (roll temperature 120 ° C., press linear pressure 4 kN / cm) was supplied and pressure-molded at a molding speed of 0.33 m / sec. A sheet-like molded body was prepared with an average thickness of 200 μm on one side of the electrode layer and an average density of the electrode sheet of 0.57 g / cm ³ .

In the production of the electrode for the electric double layer capacitor by dry molding, the current collector was changed to the current collector used in each Example or Comparative Example described in Table 1 and Table 2.
However, in Example 5, after the electrode sheet was formed, the electrode sheet was further heat-treated at 170 ° C. for 30 minutes to thermally cure the thermosetting conductive adhesive.
In Comparative Example 2, the metal fiber sheet broke during molding, and no electrode sheet was obtained.

Each characteristic of the electrode sheet was measured according to the following method.
(1) Electrode sheet density A sheet-like molded body was cut into a size of 40 mm x 60 mm, and its weight and volume were measured and calculated.
(2) Thickness and variation of electrode sheet The thickness of the electrode sheet is measured by measuring the total thickness of 20 molded sheets at intervals of 0.5 mm using a contact web thickness meter RC-101 type manufactured by Meisho Co., Ltd. Values and variations were determined. Tables 1 and 2 show the thickness of the electrode sheet, the variation in thickness, and the density of the electrode sheet.

Next, an example of producing an electrode sheet by wet forming used in the comparative example is shown.
Production of electrodes for electric double layer capacitors (Examples of production of electrodes by wet molding)
(Preparation of electrode slurry)
100 parts of an electrode active material (activated carbon with a specific surface area of 2000 m ² / g and a weight average particle diameter of 5 μm), 5 parts of a conductive material (acetylene black “Denka black powder”: manufactured by Denki Kagaku Kogyo Co., Ltd.), dispersive binder (number 5.6 parts of a solid content of a 40% aqueous dispersion “AD211” of a cross-linked acrylate polymer having an average particle size of 0.15 μm and a glass transition temperature of −40 ° C., manufactured by Zeon Corporation, a soluble resin (carboxymethylcellulose) 1.5% aqueous solution “DN-800H” (manufactured by Daicel Chemical Industries, Ltd.) is mixed to a solid content of 1.4 parts, and ion-exchanged water to a total solid content concentration of 35%. A slurry for electrodes was prepared by stirring and mixing with a “homomixer” (manufactured by Tokushu Kika Kogyo Co., Ltd.).

(Preparation of electrode sheet)
The slurry composition for an electrode was applied on a metal fiber current collector having a thickness of 60 μm shown in Comparative Example 1 in Table 2 with a doctor blade at an electrode forming speed of 5 m / min, at 60 ° C. for 20 minutes, and at 120 ° C. After drying for 20 minutes, the slurry composition was coated and dried on the backside metal fiber current collector that had not been further coated by the same method to obtain an electrode sheet having a thickness of 362 μm.

Comparative Example 6
Using the above slurry for electrodes, coating was performed by changing the metal fiber sheet of Comparative Example 1 to the current collector of Comparative Example 6 shown in Table 2, but the electrode slurry penetrated the metal fibers and was used for electrodes. The sheet could not be obtained.

(Preparation of measurement cell)
The produced electrode sheet was cut out so that the metal fiber sheet portion on which the electrode layer was not formed was 2 cm long × 2 cm wide, and the portion where the electrode layer was formed was 5 cm long × 5 cm wide. A tab material made of aluminum having a length of 7 cm, a width of 1 cm, and a thickness of 0.01 cm was ultrasonically welded to the uncoated portion. Two sets were prepared and dried at 160 ° C. for 40 minutes, and then the two electrode composition layer surfaces were opposed to each other, and a separator made of a rayon-based porous film having a length of 6 cm × width of 6 cm and a thickness of 35 μm was sandwiched therebetween. This was housed in a laminate film, vacuum impregnated with an electrolyte solution so that no air remained, the laminate film was pressure-bonded with a laminator, and sealed to produce an electric double layer capacitor. In addition, as electrolyte solution, what melt | dissolved tetraethylammonium borofluoride in the density | concentration of 1.4 mol / L in propylene carbonate was used. The storage of the electrode after the heat treatment and the assembly of the capacitor were performed in a dry room having a dew point temperature of −60 ° C. Table 1 shows the capacitance and internal resistance of the obtained electric double layer capacitor. The characteristic evaluation was performed as follows.

Method for evaluating characteristics of electric double layer capacitor The electric characteristics of the electric double layer capacitor were determined by a charge / discharge test of the electric double layer capacitor. Charging current is performed using a current value at which the current value per unit area of the electrode is 3.3 mA / cm ^2, and when the voltage reaches 2.7 V, the voltage is maintained and constant voltage charging is performed. Charging was completed when the current value dropped to 0.165 mA / cm ² . Next, immediately after the end of charging, constant current discharging was performed until the voltage reached 0 V at a current value similar to that used during charging. The capacitance was calculated from the amount of electric power at the time of discharge using an energy conversion method.

  Next, using this capacitance, charging is started at a constant current of 5 mA / F so that the charging / discharging speed of the electric double layer capacitor is constant, and the charging times of constant current charging and constant voltage charging are matched. Charging was completed at the time when the charging was carried out for 20 minutes, and then, constant current discharging was carried out immediately after the end of charging until reaching 0 V at the same current value used during charging. The internal resistance was calculated using a voltage 0.2 seconds after the start of discharge and expressed as a resistivity per volume. The capacitance was calculated from the amount of electric power during discharge using an energy conversion method, and was calculated as the capacitance density per volume of the electrode composition layer used in the electric double layer capacitor. The results are shown in Tables 1 and 2.

As mentioned above, although the Example and comparative example of the electric double layer capacitor were shown in Table 1 and 2, the sheet | seat for electrodes of Examples 1-5 using the electrical power collector which consists of a metal fiber of this invention has the dispersion | variation in thickness. It can be seen that it is small and dense. Also, looking at the electrical characteristics of the capacitor, the capacitance is high and the volume resistivity is low. On the other hand, in Comparative Example 1 in which the electrode sheet was produced by the wet molding method, the coating end surface of the electrode layer became thicker when the coating speed was increased, so that the coating speed was decreased. Also, the application of the electrode layer with a thickness of 150 μm on one side was the limit. Despite the small thickness of the electrode layer, the volume resistivity was equivalent to that of the embodiment of the present invention with 200 μm on one side. In Comparative Example 2 where the metal fibers are thick, an attempt was made to form an electrode layer by a wet forming method. However, the slurry penetrated the metal fiber sheet and the electrode sheet became thin. Therefore, evaluation of electrode layer density and electrical characteristics was not performed. In Comparative Example 3 in which the fiber diameter was 1 μm, which was thinner than 2 μm, the electrode layer was formed using the produced metal fiber sheet, but the sheet was broken and an electrode sheet could not be obtained. Further, in Comparative Example 4 using a metal fiber having a fiber diameter of 30 μm, which is thicker than 20 μm, or in Comparative Example 5 having a long fiber length, the texture of the metal fiber sheet is deteriorated. Therefore, an electrode obtained by molding The variation in the thickness of the sheet for use increased. As a result, the capacitor electrical characteristics also deteriorated.
In Comparative Example 6, the diameter of the metal fiber was increased and the length was increased. In this case, the composite particles entered the metal fiber sheet and the electrode layer became thin because the porosity of the sheet was increased. Therefore, evaluation of capacitor electrical characteristics was not performed. Comparative Example 7 is an example in which the thickness of the metal fiber sheet is increased. As far as the result of Comparative Example 7 is seen, no bad point is found, but when charged in a cell of the same size, the proportion of the current collector increases and the capacity of the cell decreases. In Comparative Examples 8 and 9, the molding speed was changed to increase the thickness of the electrode layer, and the relationship between the ratio of the thickness of (current collector) and (current collector) thickness. This is an example. The thicknesses of the electrode layers of Comparative Examples 8 and 9 are both about 400 μm on one side, but the thickness of the current collector is different. In Comparative Example 8, (the thickness of the electrode layer and the current collector combined) / (current collector thickness) The volume resistance value is larger than that of Comparative Example 9 in which (thickness of electrode layer and current collector) / (current collector thickness) does not exceed 20.

  By using a current collector made of metal fibers, it is possible to realize high capacity and low resistance of the electrochemical cell. Furthermore, it can be manufactured with high productivity by using a dry molding method. Therefore, it can be suitably used for various applications such as an application to an electric vehicle or a hybrid vehicle, a solar power generation energy storage system combined with a solar battery, and a load leveling power source combined with a battery.

The figure which shows an example of the manufacturing apparatus of the conventional electrode sheet. The figure which shows an example of the manufacturing apparatus of the sheet | seat for electrodes of this invention.

Explanation of symbols

Description of reference numerals in FIG. 1: Current collector 2: Electrochemical element electrode sheet 3: Composite particles 4: Partition plate 5. 2. Description of reference numerals in FIG. 2 1: Current collector 2: Molding roll 3: Powder supply device

Claims (10)

A method for producing a sheet for an electrochemical element electrode, comprising: supplying a powder made of an electrode material for an electrochemical element electrode onto a current collector made of a metal fiber sheet; The method for producing a sheet for an electrochemical element electrode according to claim 1, wherein the current collector made of the metal fiber sheet has a thickness of 10 to 200 µm. The total thickness of the electrode layer and the current collector formed on the current collector made of the metal fiber sheet is 50 to 1000 μm, and (the total thickness of the electrode layer and the current collector) / (the current collector Thickness) = 1-20
The method for producing a sheet for an electrochemical element electrode according to claim 1, wherein: The powder supplied on the current collector made of metal fibers is formed by combining composite particles formed by binding an electrode active material and a conductive material with a binder. The manufacturing method of the sheet | seat for electrodes for electrochemical elements of claim | item 1-3. The composite particles according to claim 4 are obtained by a step of obtaining a slurry containing an electrode active material, a conductive material, a binder, and a dispersant, and a step of spray drying and slurrying the slurry. The manufacturing method of the sheet | seat for electrochemical element electrodes of Claims 1-4. 6. The method for producing an electrochemical element electrode sheet according to claim 1, wherein the metal fiber is made of stainless steel, aluminum, nickel, copper, gold, platinum, titanium, or other alloy. The method for producing an electrochemical element electrode sheet according to claim 1, wherein the surface of the metal fiber is coated with a metal having a lower resistivity than the metal fiber. The electrochemical fiber according to claim 1, wherein the metal fiber is obtained by forming a slurry made of a metal fiber having a fiber diameter of 2 to 20 μm and a fiber length of 1 to 12 mm and a binder fiber by a wet papermaking method. Manufacturing method of sheet | seat for element electrodes. The metal fiber is made into a sheet by a wet papermaking method from a slurry composed of a metal fiber having a fiber diameter of 2 to 20 μm and a fiber length of 1 to 12 mm and a binder fiber, and further, the sheet is sintered between fibers in a hydrogen gas atmosphere. The manufacturing method of the sheet | seat for electrochemical element electrodes of Claims 1-6 characterized by the above-mentioned. When a metal fiber has a fiber diameter of 2 to 20 μm and a fiber length of 1 to 12 mm and a slurry made of a metal fiber and a binder fiber is formed into a sheet by a wet papermaking method, and the sheet is sintered between fibers in a hydrogen gas atmosphere. The method for producing a sheet for an electrochemical element electrode according to claim 1, wherein the bonded sheet is coated with a metal having a resistivity lower than that of the metal fiber.

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