CN111433944A

CN111433944A - Collector electrode sheet and method for manufacturing same, and battery and method for manufacturing same

Info

Publication number: CN111433944A
Application number: CN201880079029.XA
Authority: CN
Inventors: 平井政则; 佐藤功典; 三村和矢
Original assignee: NEC Energy Devices Ltd
Current assignee: Vision Aesc Japan Co ltd
Priority date: 2017-12-06
Filing date: 2018-11-06
Publication date: 2020-07-17
Anticipated expiration: 2038-11-06
Also published as: JPWO2019111616A1; WO2019111616A1; JP6936873B2; CN111433944B

Abstract

In a step of manufacturing a collector electrode sheet by discharging a slurry containing an active material from a die onto both surfaces of a sheet-shaped collector layer, intermittently applying the slurry, and drying the slurry to alternately form a coating region and a non-coating region of the slurry in a winding direction of the sheet-shaped collector layer, in a step of forming a terminal portion of each intermittent coating region, the slurry is discharged from the die in a state where a distance between the die and the sheet-shaped collector layer is narrower than a distance between the die and the sheet-shaped collector layer in a step of forming a central portion of each intermittent coating region, whereby a length value of a tail portion at the terminal end of the coating region is 12 times or less a thickness value of a single-sided active material layer after compression.

Description

Collector electrode sheet and method for manufacturing same, and battery and method for manufacturing same

Technical Field

The invention relates to a collector electrode sheet and a manufacturing method thereof, and a battery and a manufacturing method thereof.

Background

In recent years, in view of environmental problems, attention has been paid to electric vehicles and hybrid vehicles, and there has been a further increase in technical demand for a secondary battery as a drive source for the vehicles to have higher energy density and higher capacity.

Such an electrode for a secondary battery is produced from a current collector electrode sheet obtained by applying a slurry containing an active material onto a strip-shaped current collector layer of aluminum, copper, or the like and drying the applied slurry. The method of applying the active material can be roughly classified into an intermittent application method and a continuous application method.

The intermittent coating method is a method in which a coated region formed by coating a slurry of an active material or the like and a non-coated region not coated with the slurry are alternately formed on a strip-shaped collector layer at predetermined intervals in a winding direction of the collector layer. The non-formation portions of the active material disposed at a predetermined interval are used as portions for taking out lead tabs for electrical connection with external terminals. In the method for manufacturing a collector electrode sheet according to the present invention, a slurry obtained by mixing or kneading an active material, a conductivity-imparting agent, a binder, and a solvent as main materials is intermittently applied (hereinafter referred to as intermittent application) to one surface of a collector layer, and then the other surface on the opposite side of the collector layer is intermittently applied again, thereby applying the slurry to both surfaces of the collector layer. Next, the current collector layer coated with the slurry on both surfaces thereof was press-molded by a compression roller. Thereafter, the collector is cut into a desired outer dimension, and the electrode terminal portion is formed on the collector electrode sheet.

Here, a lithium-containing composite oxide is used as a positive electrode active material for a lithium ion secondary battery, and a large pressure is required to press-mold an active material layer containing such metal oxide particles as a main component. In particular, in a positive electrode used for a secondary battery designed to have a high energy density, since it is necessary to compress an active material layer to have a high density, the pressure molding often involves applying a higher pressure to mold the positive electrode.

In addition, an electrode used for a secondary battery designed to have a high energy density tends to have a thin collector layer as a current collector.

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 2002-164041

Disclosure of Invention

Problems to be solved by the invention

As shown in fig. 1, when the slurry is intermittently applied to the application terminal end portion of the current collector electrode sheet, a tail portion 14 of the slurry is likely to be generated at the boundary between the application region 11 and the non-application region 12. When such a tail 14 is present when the strip-shaped current collector electrode sheet 10 is compression-molded by the roll press in the winding direction Dx of the electrode roll, the active material layer is intermittently present only in the direction Dy perpendicular to the winding direction (hereinafter, also referred to as the longitudinal direction) Dx in the tail 14 at the end of the coating, and therefore, a larger linear pressure is applied than in the central portion of the coating region 11 in which the active material layer is continuously present in the direction Dy perpendicular to the winding direction Dx.

In the trailing portion 14 that receives a large line pressure in this manner, the active material particles often become significantly embedded in the metal foil 9 serving as the current collector layer. Since the remaining thickness of the foil at the portion where the active material particles are embedded in the metal foil 9 becomes extremely thin, although not shown, a crack is generated which becomes a root of the foil breakage. When the region where the crack is generated is cut in a subsequent cutting step, burrs are generated on the cut surface of the sheet electrode, the burrs being formed by the active material layer being partially peeled off. If the generated burrs adhere to the electrodes, short-circuiting occurs during battery assembly, which leads to a problem of an increase in the fraction defective of the battery.

In order to prevent the trailing portion 14 from being generated at the end of application when the slurry is intermittently applied as described above, for example, patent document 1 proposes a method of applying a fluororesin to the beginning and end of the winding direction Dx of the foil in the application region where the active material layer is applied. However, this method has problems in that the cost for coating the fluororesin increases, the weight and thickness of the electrode increase, and the method is used for manufacturing an electrode for a secondary battery designed to have a high energy density. Therefore, it is necessary to provide a method for producing an electrode with which the occurrence of burrs is suppressed and the defective rate is low even when only an active material layer is applied to a current collector electrode sheet.

The present invention has been made to solve the problems of the background art as described above, and an object thereof is to provide a current collector tab and a method for manufacturing the same, a battery and a method for manufacturing the same, which can suppress the occurrence of burrs in a cutting step without increasing the manufacturing cost.

Means for solving the problems

The collector sheet of the present invention is a collector sheet in which an active material is coated on both surfaces of a sheet-like collector layer,

the current collector layer includes on both sides: a coating region and a non-coating region of the slurry formed by intermittently coating a slurry containing the active material and drying,

the coated regions and the non-coated regions are alternately formed in a winding direction of the strip-shaped current collector layer,

the length of the trailing portion at the end of each of the coating regions is 12 times or less the thickness of the single-sided active material layer after compression.

The method for producing a collector-electrode sheet of the present invention is a method for producing a collector-electrode sheet by discharging a slurry containing an active material from a die onto both surfaces of a sheet-like collector layer, intermittently applying the slurry, and drying the slurry to alternately form a coating region and a non-coating region of the slurry in a winding direction of the collector layer,

the manufacturing method comprises the following steps: forming a leading end portion of the coating region; forming a central portion of the coating region; and a step of forming a terminal end portion of the coating region,

wherein in the step of forming the terminal portion, the slurry is discharged from the die in a state where a distance between the die and the collector layer is narrower than a distance between the die and the collector layer in the step of forming the central portion.

The second electrode collector sheet of the present invention is produced by the above-described method for producing a collector sheet of the present invention.

The method for manufacturing a battery of the present invention includes the steps of: forming a positive electrode active material layer on both surfaces of a sheet-like current collector layer to form a positive electrode current collector electrode sheet; forming a negative electrode active material layer on both surfaces of a sheet-like current collector layer to form a negative electrode current collector tab; cutting the positive electrode collector tab and the negative electrode collector tab into predetermined sizes, thereby forming a positive electrode and a negative electrode, respectively; a step of laminating the positive electrode and the negative electrode with a separator interposed therebetween,

wherein either or both of the step of forming the positive electrode collector tab and the step of forming the negative electrode collector tab include the respective steps of the above-described method for manufacturing a collector tab of the present invention.

The battery of the present invention comprises at least a positive electrode, a negative electrode and an electrolyte, wherein,

either or both of the positive electrode and the negative electrode is formed by cutting the current collector tab of the present invention into a predetermined size.

It should be noted that a configuration converted from a method, an apparatus, a system, a recording medium, a computer program, and the like, with respect to any combination of the above-described constituent elements and the expression of the present invention, is also effective as a configuration of the present invention.

In addition, the various components of the present invention are not necessarily required to be individually and independently present, and a plurality of components may be formed as one member, one component may be formed of a plurality of members, a certain component may be a part of another component, a part of a certain component may overlap with a part of another component, or the like.

The method and the computer program of the present invention describe a plurality of steps (or steps) in sequence, but the description order is not limited to the order in which the plurality of steps are performed. Therefore, when the method and the computer program of the present invention are implemented, the order of the steps can be changed within a range that does not hinder the contents.

Further, the plurality of steps (or steps) of the method and the computer program of the present invention are not limited to being executed at different times. Therefore, other steps may occur during execution of a certain step, the execution time of a certain step may partially or entirely overlap with the execution time of another step, and the like.

Effects of the invention

According to the present invention, it is possible to provide a collector tab and a manufacturing method thereof, and a battery and a manufacturing method thereof, which can suppress the occurrence of burrs in the cutting step of the collector tab without increasing the manufacturing cost.

Drawings

The above and other objects, features and advantages will be further apparent from the following description of the preferred embodiments taken in conjunction with the following drawings.

Fig. 1 is a plan view showing a current collector electrode sheet after both surfaces of an active material are coated by an intermittent coating method.

Fig. 2 is a plan view showing the collector electrode sheet after both surfaces are coated in the embodiment of the present invention.

Fig. 3 is a plan view and a cross-sectional view showing the collector electrode sheet after both-side coating in the embodiment of the present invention.

Fig. 4 is a schematic view showing an outline of a slurry coating apparatus for an electrode sheet according to an embodiment of the present invention.

Fig. 5 is a schematic view showing an example of a die coater section in a slurry coating apparatus for an electrode sheet according to an embodiment of the present invention.

Fig. 6 is a block diagram showing an example of a hardware configuration of a computer that realizes each device of the electrode sheet manufacturing system according to the embodiment of the present invention.

Fig. 7 is a diagram schematically showing the operation of each apparatus during slurry application in the method for manufacturing an electrode sheet according to the embodiment of the present invention.

Fig. 8 is a schematic diagram showing an outline of the compression device for electrode sheets according to the embodiment of the present invention.

Fig. 9 is a schematic diagram showing an outline of a cutting device that cuts the electrode sheet according to the embodiment of the present invention into a plurality of sheets.

Fig. 10 is a schematic diagram showing an example of the structure of the battery according to the embodiment of the present invention.

Fig. 11 is a block diagram showing a configuration example of a system for manufacturing a collector electrode sheet according to the present embodiment.

Fig. 12 is a flowchart showing steps of the method for manufacturing a collector electrode sheet according to the present embodiment.

Fig. 13 is a flowchart showing an example of the processing procedure of the control program according to the present embodiment.

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, the same components are denoted by the same reference numerals, and the description thereof is omitted as appropriate. The drawing is a schematic diagram and does not match the actual size ratio. In addition, "a to B" in the numerical range means a to B, unless otherwise specified.

< electrode and method for producing electrode >

The following describes the collector tab 10 and the method for manufacturing the collector tab 10 according to the present embodiment.

Fig. 2 is a plan view showing an example of the structure of the current collector electrode sheet 10 according to the embodiment of the present invention.

Fig. 3(a) is a plan view showing a part of the collector electrode sheet 10 after both surfaces are coated according to the embodiment of the present invention. Fig. 3(b) is a cross-sectional view of the collector electrode sheet 10 of fig. 3(a) as viewed from the line I-I.

The method for manufacturing the collector electrode sheet 10 according to the present embodiment is a method for manufacturing an electrode including a collector layer (metal foil 9) and an electrode active material layer (coating region 11).

As described above, according to the study of the present inventors, it was clarified that the electrode manufactured by the intermittent coating method is likely to generate burrs in the subsequent cutting step.

As a result of extensive studies based on the above findings, the present inventors have found that the occurrence of burrs in the cutting step can be effectively suppressed by forming a collector electrode sheet 10 in which the length value (Z in fig. 3 (b)) of the tail portion 14 at the terminal end 13 of the intermittently applied coating region 11 is 12 times or less the thickness value (T in fig. 3 (b)) of the one-side active material layer (coating region 11) after compression.

Further, according to the method for manufacturing the collector electrode sheet 10 of the present embodiment, by using the method for manufacturing the collector electrode sheet 10 in which the slurry is discharged from the die in the state where the interval between the die and the sheet-shaped collector layer (metal foil 9) in the step of forming the terminal end portion of each intermittent coating region 11 is narrower than the interval between the die and the sheet-shaped collector layer (metal foil 9) in the step of forming the central portion of each intermittent coating region 11, the collector electrode sheet 10 in which the length value (Z in fig. 3 (b)) of the tail portion 14 at the terminal end 13 of the intermittently coated coating region 11 is 12 times or less the thickness value (T in fig. 3 (b)) of the one-side active material layer (coating region 11) after compression can be stably obtained.

Further, according to the present embodiment, there is provided a method for manufacturing a current collector electrode sheet for a battery, including a step of applying a slurry to a current collector, drying the applied slurry, and removing a solvent to form an active material layer on the current collector.

Further, according to the present embodiment, there is provided an electrode sheet for a battery including a current collector and an active material layer provided on at least one surface of the current collector and formed of a solid component of a slurry.

As described above, according to the method for manufacturing the collector electrode sheet 10 of the present embodiment, an electrode in which the occurrence of burrs is suppressed can be provided.

The following describes the configuration of the collector tab 10 and the respective steps in the method for manufacturing the collector tab 10 in detail.

First, each component constituting the electrode active material layer described in the present embodiment will be described.

The electrode active material layer contains an electrode active material, and if necessary, contains a binder resin, a conductive assistant, a thickener, and the like.

The electrode active material contained in the electrode active material layer according to the present embodiment is appropriately selected depending on the application. The positive electrode active material is used for producing the positive electrode, and the negative electrode active material is used for producing the negative electrode.

The positive electrode active material is not particularly limited as long as it is a general positive electrode active material that can be used for a positive electrode of a lithium ion battery. Examples thereof include composite oxides of lithium and transition metals such as lithium-nickel composite oxides, lithium-cobalt composite oxides, lithium-manganese composite oxides, lithium-nickel-cobalt composite oxides, lithium-nickel-aluminum composite oxides, lithium-nickel-cobalt-aluminum composite oxides, lithium-nickel-manganese-cobalt composite oxides, lithium-nickel-manganese-aluminum composite oxides, and lithium-nickel-cobalt-manganese-aluminum composite oxides; TiS₂、FeS、MoS₂Isotransition metal sulfides; MnO and V₂O₅、V₆O₁₃、TiO₂And transition metal oxides, olivine-type lithium phosphorus oxides, and the like.

The olivine-type lithium phosphorus oxide contains at least 1 element selected from, for example, Mn, Cr, Co, Cu, Ni, V, Mo, Ti, Zn, Al, Ga, Mg, B, Nb, and Fe, lithium, phosphorus, and oxygen. In order to improve the properties, some elements in these compounds may be partially substituted with other elements.

Among these, preferred are olivine-type lithium iron phosphorus oxides, lithium-nickel composite oxides, lithium-cobalt composite oxides, lithium-manganese composite oxides, lithium-nickel-cobalt composite oxides, lithium-nickel-aluminum composite oxides, lithium-nickel-cobalt-aluminum composite oxides, lithium-nickel-manganese-cobalt composite oxides, lithium-nickel-manganese-aluminum composite oxides, and lithium-nickel-manganese-aluminum composite oxides. These positive electrode active materials have a high action potential, a large capacity, and a large energy density.

The positive electrode active material may be used alone or in combination of two or more.

The negative electrode active material is not particularly limited as long as it is a general negative electrode active material that can be used for a negative electrode of a lithium ion battery. Examples of the carbon material include natural graphite, artificial graphite, resin carbon, carbon fiber, activated carbon, hard carbon, and soft carbon; lithium metal materials such as lithium metal and lithium alloys; metal materials such as silicon and tin; and conductive polymer materials such as polyacene, polyacetylene, and polypyrrole. Among these, carbon materials are preferable, and graphite materials such as natural graphite and artificial graphite are particularly preferable.

The negative electrode active material may be used alone in 1 kind, or may be used in combination in 2 or more kinds.

The average particle diameter of the electrode active material is preferably 1 μm or more, more preferably 2 μm or more, from the viewpoint of suppressing side reactions during charge and discharge and suppressing a decrease in charge and discharge efficiency, and is preferably 100 μm or less, more preferably 50 μm or less, from the viewpoint of input and output characteristics and electrode production (e.g., electrode surface smoothness). Here, the average particle diameter means a particle diameter (median diameter: D) at which the cumulative value in the particle size distribution (volume basis) by the laser diffraction scattering method is 50%₅₀)。

The content of the electrode active material is preferably 85 parts by mass or more and 99.8 parts by mass or less, when the total amount of the electrode active material layer is 100 parts by mass.

The binder resin included in the electrode active material layer according to the present embodiment may be appropriately selected according to the application. For example, a fluorine-based binder resin that can be dissolved in a solvent, an aqueous binder that can be dispersed in water, or the like can be used.

The fluorine-based binder resin is not particularly limited as long as it can be used for electrode molding and has sufficient electrochemical stability, and examples thereof include polyvinylidene fluoride-based resins and fluororubbers. These fluorine-based binder resins may be used alone or in combination of two or more. Among these, polyvinylidene fluoride resins are preferable. The fluorine-based binder resin can be used by dissolving in a solvent such as N-methyl-pyrrolidone (NMP).

The aqueous binder is not particularly limited as long as it can form an electrode and has sufficient electrochemical stability, and examples thereof include polytetrafluoroethylene-based resins, polyacrylic resins, styrene-butadiene-based rubbers, and polyimide-based resins. These water-based binders may be used alone or in combination of two or more. Among these, styrene-butadiene rubber is preferable.

In the present embodiment, the aqueous binder means a binder capable of forming an aqueous emulsion solution by dispersing in water.

When an aqueous binder is used, a thickener may be further used. The thickener is not particularly limited, and examples thereof include cellulose polymers such as carboxymethyl cellulose, methyl cellulose, and hydroxypropyl cellulose, and ammonium salts and alkali metal salts thereof; a polycarboxylic acid; polyethylene oxide; polyvinylpyrrolidone; polyacrylates such as sodium polyacrylate; water-soluble polymers such as polyvinyl alcohol.

The content of the binder resin is preferably 0.1 part by mass or more and 10.0 parts by mass or less, when the entire electrode active material layer is 100 parts by mass. When the content of the binder resin is within the above range, the balance of the applicability of the electrode paste, the adhesiveness of the binder, and the battery characteristics is more excellent.

When the content of the binder resin is not more than the upper limit, the proportion of the electrode active material increases, and the capacity per electrode mass increases, which is preferable. When the content of the binder resin is not less than the lower limit, electrode peeling is suppressed, which is preferable.

The conductive aid contained in the electrode active material layer according to the present embodiment is not particularly limited as long as it improves the conductivity of the electrode, and examples thereof include carbon black, ketjen black, acetylene black, natural graphite, artificial graphite, and carbon fiber. These conductive aids may be used alone in 1 kind, or may be used in combination in 2 or more kinds.

The content of the conductive auxiliary is preferably 0.1 part by mass or more and 5.0 parts by mass or less, when the entire electrode active material layer is 100 parts by mass. When the content of the conductive aid is within the above range, the balance of the coatability of the electrode paste, the adhesiveness of the binder, and the battery characteristics is more excellent.

When the content of the conductive auxiliary agent is not more than the upper limit, the proportion of the electrode active material increases, and the capacity per electrode mass increases, which is preferable. When the content of the conductive additive is not less than the lower limit, the conductivity of the electrode becomes better, and therefore, it is preferable.

In the electrode active material layer according to the present embodiment, the content of the electrode active material is preferably 85 parts by mass or more and 99.8 parts by mass or less, based on 100 parts by mass of the entire electrode active material layer. The content of the binder resin is preferably 0.1 parts by mass or more and 10.0 parts by mass or less. The content of the conductive aid is preferably 0.1 parts by mass or more and 5.0 parts by mass or less.

When the content of each component constituting the electrode active material layer is within the above range, the handling property of the current collector electrode sheet 10 and the battery characteristics of the obtained lithium ion battery are particularly excellent in balance.

The density of the electrode active material layer is not particularly limited, and when the electrode active material layer is a positive electrode active material layer, for example, 2.0g/cm is preferable³Above and 4.0g/cm³Hereinafter, more preferably 2.4g/cm³Above and 3.8g/cm³Hereinafter, more preferably 2.8g/cm³Above and 3.6g/cm³The following. When the electrode active material layer is a negative electrode active material layer, for example, it is preferably 1.2g/cm³Above and 2.0g/cm³Hereinafter, more preferably 1.3g/cm³Above and 1.9g/cm³Hereinafter, more preferably 1.4g/cm³Above and 1.8g/cm³The following.

When the density of the electrode active material layer is within the above range, the discharge capacity when used at a high discharge rate is improved, which is preferable.

Here, as the density of the electrode active material layer is higher, the electrode active material particles constituting the electrode active material layer are embedded deeper into the metal foil 9 as the current collector layer, and therefore, the thickness of the metal foil 9 of the trailing portion 14 is reduced, and the strength of the metal foil 9 is weakened, so that burrs tend to be generated in the cutting step. However, according to the method for manufacturing the collector electrode sheet 10 of the present embodiment, even if the density of the electrode active material layer is high, the occurrence of burrs in the cutting step can be effectively suppressed.

Therefore, the density of the positive electrode active material layer is preferably 3.0g/cm from the viewpoint of effectively suppressing the occurrence of burrs on the current collector electrode sheet 10 and further improving the energy density of the resulting lithium ion battery³Above, more preferably 3.2g/cm³Above, 3.3g/cm is particularly preferable³As described above, the density of the negative electrode active material layer is preferably 1.5g/cm³Above, more preferably 1.6g/cm³The above. In addition, from the viewpoint of further suppressing deterioration of cycle characteristics at high temperatures, the density of the positive electrode active material layer is preferably 4.0g/cm³Hereinafter, more preferably 3.8g/cm³Hereinafter, more preferably 3.6g/cm³The density of the negative electrode active material layer is preferably 2.0g/cm³Hereinafter, more preferably 1.9g/cm³Hereinafter, more preferably 1.8g/cm³The following.

The thickness of the electrode active material layer is not particularly limited, and may be appropriately set according to desired characteristics. For example, the thickness can be set to be thick from the viewpoint of energy density, and the thickness can be set to be thin from the viewpoint of output characteristics. The thickness (single-sided thickness) of the electrode active material layer can be appropriately set in a range of, for example, 10 μm or more and 250 μm or less, preferably 20 μm or more and 200 μm or less, and more preferably 30 μm or more and 150 μm or less.

The current collector layer according to the present embodiment is not particularly limited, and aluminum, stainless steel, nickel, titanium, an alloy thereof, or the like can be used as the positive electrode current collector layer. Examples of the shape include foil, flat plate, and mesh. Aluminum foil may be particularly suitably used.

As the negative electrode collector layer, copper, stainless steel, nickel, titanium, or an alloy thereof can be used. Examples of the shape include foil, flat plate, and mesh. Copper foil can be particularly suitably used.

The thickness of the positive electrode collector layer is not particularly limited, and is, for example, 1 μm or more and 30 μm or less. The thickness of the negative electrode collector layer is not particularly limited, and is, for example, 1 μm or more and 20 μm or less.

Here, the thinner the thickness of the metal foil 9 as the collector layer is, the weaker the strength of the metal foil 9 of the tab portion 14 is, and therefore, burrs tend to be easily generated in the cutting step. However, according to the method for manufacturing the collector electrode sheet 10 of the present embodiment, even if the thickness of the metal foil 9 is small, the occurrence of burrs in the cutting step can be effectively suppressed.

Therefore, from the viewpoint of effectively suppressing the occurrence of burrs on the current collector electrode sheet 10, reducing the proportion of the current collector layer in the obtained lithium ion battery, and further increasing the energy density of the lithium ion battery, the thickness of the positive electrode current collector layer is preferably less than 25 μm, more preferably less than 20 μm, and particularly preferably less than 18 μm, and the thickness of the negative electrode current collector layer is preferably less than 15 μm, more preferably less than 12 μm, and particularly preferably less than 10 μm.

Hereinafter, a method for manufacturing an electrode in the method for manufacturing a battery according to the present invention will be described in detail.

First, an electrode paste is prepared.

The electrode slurry may be prepared by mixing an electrode active material, a binder resin according to need, a conductive assistant, and a thickener. The blending ratio of the electrode active material, the binder resin, and the conductive assistant is the same as the content ratio of the electrode active material, the binder resin, and the conductive assistant in the electrode active material layer, and therefore, the description thereof is omitted here.

The electrode slurry is obtained by dispersing or dissolving an electrode active material, a binder resin, a conductive additive, and a thickener as needed in a solvent.

The mixing step of the respective components is not particularly limited, and for example, the electrode active material and the conductive assistant are dry-mixed, and then the binder resin and the solvent are added and wet-mixed to prepare the electrode slurry.

In this case, as the mixer to be used, a known mixer such as a ball mill or a planetary mixer can be used, and there is no particular limitation.

As the solvent used in the electrode slurry, an organic solvent such as N-methyl-2-pyrrolidone (NMP) or water can be used.

In the present embodiment, the prepared slurry is subjected to a shear rate of 3.4s at 25 ℃ using, for example, a type B viscometer (Brookfield, rotational viscometer)^-1When the measurement is performed under the condition (1), the range of 2000 mPas to 20000 mPas is preferable. The solid content concentration of the slurry is preferably 50 to 83 mass%.

The electrode slurry thus prepared was used to manufacture the collector electrode sheet 10.

Fig. 11 is a block diagram showing an example of the configuration of the manufacturing system 1 of the collector electrode sheet 10 according to the present embodiment.

The manufacturing system 1 includes a slurry application device 20, a compression device 40, and a cutting device 60. Further, a control mechanism for controlling each device of the manufacturing system 1 may be provided. In the present embodiment, a control means (sequencer) 207 (fig. 7) described later is provided.

The slurry application device 20, the compression device 40, and the cutting device 60 are each realized by any combination of hardware and software of a computer 100 (fig. 6) described later. Moreover, those skilled in the art can understand various modifications of the method and apparatus for implementing the same.

The program 110 (fig. 6) may be recorded in a recording medium that can be read by the computer 100. The recording medium is not particularly limited, and various types of recording media can be considered. The program may be loaded from a recording medium into the memory 104 of the computer 100, may be downloaded to the computer 100 via a network, or may be loaded into the memory 104.

The recording medium on which the program 110 is recorded includes a non-transitory tangible computer 100 usable medium in which a program code readable by the computer 100 is embedded. When the program 110 is executed on the computer 100, the computer 100 executes a method of manufacturing an electrode sheet that realizes each device.

Fig. 12 is a flowchart showing steps of the method for manufacturing the collector electrode sheet 10 according to the present embodiment.

The method of manufacturing the collector electrode sheet 10 of the present embodiment includes a coating step (S1), a compression step (S5), and a cutting step (S6). The collector electrode sheet 10 according to the present embodiment is manufactured by the manufacturing method shown in fig. 12. Details of each step will be described later together with the description of each apparatus.

Fig. 4 is a schematic diagram showing an outline of the slurry coating device 20 for an electrode sheet according to the embodiment of the present invention.

Fig. 5 is a schematic view showing an example of a die coater 21 and a die coater 22 for applying a slurry and intermittently coating the slurry in the slurry coating apparatus 20 for an electrode sheet according to the embodiment of the present invention.

First, in the coating step (S1 in fig. 12), a slurry containing an active material is intermittently applied to the one surface 9a of the metal foil 9 provided in the coating apparatus 20 by using, for example, the first die coater 21, and dried, thereby forming the active material (slurry) coated region 11.

The obtained electrode slurry was intermittently applied along the longitudinal direction of the strip-shaped metal foil 9 using a die coater including a die, dried, and the solvent was removed, whereby an electrode active material layer was intermittently formed on at least one surface of the metal foil 9 so as to alternately repeat the applied portions and the non-applied portions.

Here, as shown in fig. 5, the die coater 21 for performing intermittent coating is provided with a die 200, an application valve 201 connected to the die 200, a pump 202, and a tank 204 for storing a slurry 203 of an active material mixture. A relative movement mechanism for moving the metal foil 9 relative to the die head 200 is disposed at a position facing the die head 200. In the present embodiment, the metal foil 9 serving as a current collector on which an active material layer is to be formed is conveyed by rotation of the roller 27 as an example of the relative movement mechanism.

For example, the rotation speed of the roller 27 is controlled within a range of 10m/min to 80 m/min.

The die 200 is driven by a servo motor 205 as a die moving mechanism and can be moved toward and away from the roller 27, and the displacement (moving amount) of the die 200 is detected by a displacement sensor 206. The control mechanism (sequencer) 207 controls the operation of the servo motor 205 based on a control program described later. The manufacturing apparatus may be provided with a return path for returning the slurry from the die 200 to the tank 204, or a return valve may be provided on the return path.

When the gap (clearance) between the die 200 and the metal foil 9 in the central portion (302 in fig. 7) of the application region of the active material layer is set to 100%, the amount of displacement (movement) of the die 200 when transferring to the terminal portion (303 in fig. 7) of the application region is preferably controlled to be in the range of 10% to 50%, and more preferably in the range of 30% to 50%.

Fig. 6 is a block diagram showing an example of a hardware configuration of the computer 100 that realizes each device including the control means (sequencer) 207 according to the embodiment of the present invention.

The computer 100 includes a cpu (central Processing unit)102, a memory 104, a program 110 including a control program for regulating the operation of a servo motor 205 loaded in the memory 104, a storage 105 for storing the program 110, an I/o (input output)106, and a communication interface (I/F)107 for network connection. The CPU102 and the respective elements are connected to each other via a bus 109, and the CPU102 controls respective devices such as a control mechanism (sequencer) 207. However, the method of interconnecting the CPUs 102 and the like is not limited to the bus connection.

The CPU102 can realize each function of each device by reading the program 110 stored in the storage 105 into the memory 104 and running it.

The program 110 including a control program for controlling the operation of the servo motor 205 is implemented by any combination of hardware and software of the computer 100. Moreover, those skilled in the art can understand various modifications of the method and apparatus for implementing the same.

A control program for controlling the operation of the servo motor 205 will be described below.

In the control program according to the embodiment of the present invention, at least the length 1 in the longitudinal direction of each of the intermittently applied application regions, the rotation speed v of the roll, and the average thickness T of the active material layer in the center of the application region on one surface of the collector electrode sheet at the end of the application and drying step (not shown) of the slurry to the collector layer are set as parameters. Then, before starting the intermittent coating process, the resultant is input to a control means (sequencer) 207. The values of the parameters may be input by an operator in accordance with an operation screen of the control program, or may be read from a setting file stored in advance.

The control program calculates, based on the input parameters, the appropriate distance d (hereinafter also referred to as a gap) between the die 200 and the metal foil 9 for forming the start end, the center portion, the end portion, and the non-application regions of the intermittently applied application regions, respectively, calculates the time at which the distance d is adjusted by adjusting the position of the distance between the die 200 and the metal foil 9 or the conveyance speed of the current collector 9 caused by the rotation of the roller 27, and causes the servo motor 205 to operate.

Fig. 7 is a diagram for explaining the details of the coating step (S1 in fig. 12) in the present embodiment.

Fig. 7 schematically shows the operation of the control routine according to the embodiment of the present invention, and the interval d (gap) between the die 200 and the metal foil 9 is changed depending on the position of each of the intermittently formed coating regions or the elapsed time t after the start of coating.

First, the leading end portion 301 of the coating region is formed (step S10). The starting position of the formation of the starting end portion is defined as x₀Let the start time be t₀. Then, the rotation of the roller 27 is started (step S11). The die 200 is brought close to the roller 27 and the metal foil 9, and the gap (clearance) between the die 200 and the metal foil 9 is d₁(step S12), the application valve 201 is opened, the pump 202 is adjusted, and the predetermined discharge pressure is set (step S13). The metal foil 9 as a belt-shaped current collector sheet is passed right under the discharge port of the die 200 by the rotation of the holding roller 27, thereby forming a sheet continuously coated with the slurry in the longitudinal directionThe leading end 301 of the coating region of the desired length (step S10). Here, the ending position of the starting end portion 301 of the application region, that is, the starting position of the central portion 302 of the application region is represented as x₁T represents the time when the formation of the starting end portion 301 is completed₁Regarding the length of the starting end 301 of the application region: x is the number of₁-x₀And may be determined appropriately according to the design of the battery.

Then, at time t₁If so (yes in step S14), the process proceeds to the formation of the central portion 302 of the application region (step S20). With the application valve 201 open, the metal foil 9 as a strip-shaped current collector sheet is passed directly below the discharge port of the die 200 by the rotation of the roller 27, and the central portion 302 of the application region of a desired length is formed. Depending on the need to change the thickness of the active material layer formed in the leading end portion 301 and the central portion 302, the gap between the die 200 and the metal foil 9 can be changed to d while shifting to the formation of the central portion 302₂The pump 202 may be adjusted to change the discharge flow rate and the discharge pressure (not shown) (step S21). Here, the ending position of the central portion 302 of the application region, that is, the starting position of the terminal portion 303 of the application region is represented as x₂The time point when the formation of the central portion 302 is completed is t2, and the total length (x) of the leading end portion 301 and the central portion 302 of the application region is set to₂-x₀) Preferably, the total length of the beginning portion, the central portion, and the end portion of the application region is in a range of 88% to 93%. The specific value within the above range should be appropriately determined depending on the viscosity of the slurry used for production and the thickness of the active material layer to be formed.

Then, at time t₂If so (yes in step S22), the process proceeds to the formation of the terminal end 303 of the application region (step S30). At time t when the transfer is to the end 303 of the application region₂While keeping the coating valve 201 open, the gap (clearance) between the die 200 and the metal foil 9 is set to be d₂The metal foil 9, which is a strip-shaped current collector sheet, is formed by passing the metal foil through the discharge port of the die 200 directly below the discharge port by the rotation of the roller 27 while changing to d3 (step S31)The terminal end 303 of the desired length of the coated region. The gap (clearance) d between the die 200 and the current collector 9 in the formation of the terminal end 303 of the coating region₃Preferably, the distance (gap) d between the die 200 and the current collector 9 in the formation of the central part 302 of the coating region ₂50% to 70%. When the formation of the central portion 302 of the application region is shifted to the formation of the terminal portion 303 of the application region, it is preferable that the discharge flow rate and the discharge pressure are not changed by the adjustment pump 22.

The end position of the end portion 303 of the application region, that is, the start position of the non-application region 12 is represented by x₃The time when the formation of the terminal portion 303 is completed is t₃。

In this way, the gap (clearance) d between the die 200 and the metal foil 9 in the formation of the terminal end 303 of the application region₃The distance (gap) d between the die 200 and the metal foil 9 in the formation of the central part 302 of the coating region ₂50% to 70%, and the position (x) of formation of the end portion 303 of the application region is switched from the central portion 302 of the application region to the end portion 302 of the application region₂-x₀) The total length (x) of the starting end 301, the central portion 302, and the terminal end 303 of the application region is defined as₃-x₀) In the range of 88% to 93%. Thereby, the following collector electrode sheet 10 can be obtained: the length value of the tail portion 14 at the terminal end of the coated region is 12 times or less the thickness value of the single-sided active material layer after compression under pressure. Here, if x₂-x₀Is less than x₃-x₀88% of the total, the thickness of the active material layer may not satisfy the design value at the terminal end 303 of the application region, and if it is 94% or more, the length of the trailing portion 14 cannot be sufficiently shortened.

The reason why the smear length can be made constant or less is not necessarily clear by controlling the application start position of the terminal end portion 303 of the application region and the gap (clearance) between the die and the current collector, but the following reason can be considered.

Regarding tailing at the final end of the coating area, due to the influence of the limit performance of the coating valve, when the coating of the active material (slurry) is cut off, the cutoff of the slurry becomes poorThereby creating a trailing condition of the slurry and thus a tailing. By making the die spaced from the current collector by a distance d₃A distance (gap) d between the die and the current collector in the center₂Since the amount of the slurry contributing to the dragging when the coating is cut is reduced, the discharge pressure is increased and the amount of the slurry applied is reduced. Here, in order to reduce the amount of tailing, d₃Is preferably set to d₂Is 90% or less, and is more preferably d₂The value of (A) is 70% or less. On the other hand, if d₃Reduced to d₂When the discharge pressure is not more than 50%, the flow of the slurry discharged from the discharge port is deteriorated due to an excessive rise in the discharge pressure. Therefore, it is considered that d₃Is set to d ₂50% to 70% of these are suitable.

Further, the total length x of the starting end portion and the central portion is determined₂-x₀Length x defined as the whole of the coating region₃-x₀The range of 88% to 93% of (d) is considered to be such that the amount of the slurry discharged from the discharge port of the die is gradually reduced, but the thickness applied to the terminal portion can be stably maintained to be equal to the thickness of the central portion while only the tail is reduced.

Then, at the arrival time t₃If so (yes in step S32), the process proceeds to the formation of the non-coated region 12 (step S40). At the time t of transition to the formation of the non-coated region 12₃The application valve 201 is closed without discharging the slurry from the die 200 (step S41), and the metal foil 9 is conveyed by a desired length by the rotation of the roller 27. The end position of the non-application region 12, i.e., the start position of the start end 301 of the next application region is defined as x₄The time when the formation of the non-application region 12 is ended is t4 (yes in step S42).

At a later time, the formation of the leading end portion 301, the central portion 302, the terminal end portion 303, and the non-application region 12 of the application region is repeated in this order (return to step S12), and a plurality of active material layers (application regions 11) are formed. The thickness of the leading end portion 301 and the central portion 302 of the active material layer application region, the total length and width of the leading end portion 301, the central portion 302, and the terminal portion 303 of the active material layer application region, and the length of the non-application region 12 may be appropriately determined according to the size of the battery.

As described above, after the collector electrode sheet 10 having the active material application region 11 applied to one surface 9a of the metal foil 9 as the collector layer is dried by the dryer 25, the active material application region 11 is formed on the other surface 9b of the metal foil 9 in the same manner. At this time, the start detector 24 detects the position of the active material application region formed on the one surface 9a on the other surface 9 b. By using the die coater 22 or the like which operates upon receiving the detection signal of the start end detector 24, the active material application regions 11 are formed in the portions of the other surface 9b which is the back surface of the one surface 9a at positions corresponding to the detection positions on the one surface 9a, so that the positions of the active material application regions 11 formed on both surfaces of the collector electrode sheet 10 are aligned with each other. The start and end positions of application of the active material (slurry) also coincide with each other on both surfaces of the current collector electrode sheet 10. The amount of positional deviation of the active material (slurry) on both surfaces of the collector electrode sheet 10 from the start of application is adjusted to be, for example, less than 1mm in the winding direction Dx thereof. The drying method is not particularly limited, and examples thereof include a method of indirectly heating the electrode slurry from the current collector layer side or the electrode active material layer side which has been dried using a heating roller to dry the electrode slurry; a method of drying the electrode paste using an electromagnetic wave such as an infrared ray, far infrared ray, or near infrared ray heater; and a method of drying the electrode slurry by indirectly heating the electrode slurry by blowing hot air from the current collector layer side or the electrode active material layer side which has been dried.

Fig. 8 is a schematic diagram showing an outline of the compression device 40 for the collector electrode sheet 10 according to the embodiment of the present invention.

In the compressing step (S5 in fig. 12), the collector electrode sheet 10 having the active material application regions 11 formed on both surfaces of the collector layer by the slurry applicator 20 shown in fig. 4 is compressed by the pair of compressing rollers 50 as shown in fig. 8. The collector electrode sheet 10 is compressed by pressure when passing through the gap between the pair of compression rollers 50, and is wound in the winding direction Dx.

In the compression step, the flow direction of the current collector electrode sheet 10, that is, the winding direction Dx may be set from the coating end side to the coating start end side, or conversely may be set from the coating start end side to the coating end side.

In the compression step, the compression device 40 can appropriately set the load applied to the central portion of the application region 11 in the metal foil 9, which is the current collector layer on which the active material layer is formed, according to the desired electrode density, and can apply pressure so as to be, for example, 0.2 to 3 ton/cm. The size of the compression roller is not particularly limited, and for example, a compression roller having a roller radius r of 250mm to 375mm may be used.

In this compression step, in the conventional method, the trailing portion 14 is compressed more than the central portion of the coating region, and a phenomenon in which a large number of active material particles are embedded in the collector layer often occurs. Since the remaining thickness of the collector layer at the portion where the active material particles are embedded in the collector layer is extremely thin, cracks that are the root of foil breakage are likely to occur, although not shown. On the other hand, in the current collector tab formed by the method described in the embodiment of the present invention, cracks are not generated in the tail portion 14 even in the compression step. The reason is not necessarily clear, but the following reason may be considered. In the trailing portion 14 formed by the conventional method, since the active material layer is intermittently present only in the direction Dy perpendicular to the winding direction Dx, a larger linear pressure is applied to the central portion of the application region where the active material layer is continuously present in the direction Dy perpendicular to the winding direction Dx. On the other hand, it can be considered that: in the method according to the embodiment of the present invention, the length of the tail portion 14 is sufficiently short, and the active material layer is present almost continuously in the Dy direction in the tail portion 14. Therefore, there is little difference between the line pressure at the coating center portion and the tail portion 14, and embedding of the active material particles into the current collector layer is also suppressed, and therefore, cracking of the foil is not generated.

Fig. 9 is a schematic diagram showing an outline of the cutting device 60 according to each embodiment of the present invention.

The cutting device 60 cuts the collector electrode sheet 10 into a plurality of sheets. The cutting device 60 includes a 1 st cutting blade 61, a 2 nd cutting blade 62, 2 support rollers 63, and a pair of guide rollers 64.

The collector electrode sheet 10 is cut into a predetermined size, and a plurality of electrodes can be obtained. The method of cutting out the electrodes from the collector electrode sheet 10 is not particularly limited, and examples thereof include a method of cutting out a plurality of electrodes having a predetermined width by cutting out the collector electrode sheet 10 in parallel to the longitudinal direction thereof (cutting along the line 17 to cut out in the winding direction of fig. 1). Further, the electrode for a battery can be obtained by punching the electrode into a predetermined size according to the application. Here, the method of cutting the collector electrode sheet 10 is not particularly limited, and the collector electrode sheet 10 may be cut using a blade made of metal or the like, for example.

In this cutting step (S6 in fig. 12), in the conventional method, although burrs are generated from the position where the cracks are generated at the tape base portion as a starting point in the compression step, if the method described in the present embodiment of the present invention is used, no cracks are generated in the foil, and therefore generation of burrs is not observed.

As described above, in the battery of the present invention, the electrode is completed. Next, a method for manufacturing a battery using the manufactured electrode will be described.

< Battery >

Fig. 10 is a schematic diagram showing an example of the structure of the laminated battery 150 according to the embodiment of the present invention.

The battery according to the present embodiment includes the current collector tab 10 according to the present embodiment. Hereinafter, the battery according to the present embodiment will be described using a typical example of the laminated battery 150 in which the battery is a lithium ion battery.

The laminated battery 150 includes battery elements in which a plurality of positive electrodes 121 and negative electrodes 126 are alternately laminated with separators 120 interposed therebetween, and these battery elements are accommodated in a container including a flexible film 140 together with an electrolyte (not shown). The battery element is electrically connected to the positive electrode terminal 131 and the negative electrode terminal 136, and a part or all of the positive electrode terminal 131 and the negative electrode terminal 136 is drawn out to the outside of the flexible film 140.

In the positive electrode 121, a coated portion (positive electrode active material layer 122) and a non-coated region of the positive electrode active material are provided on the front and back surfaces of the positive electrode current collector layer 123, and in the negative electrode 126, a coated portion (negative electrode active material layer 127) and a non-coated region of the negative electrode active material are provided on the front and back surfaces of the negative electrode current collector layer 128.

The non-coated region of the positive electrode active material in the positive electrode collector layer 123 is defined as a positive electrode tab 130 for connection to a positive electrode terminal 131, and the non-coated region of the negative electrode active material in the negative electrode collector layer 128 is defined as a negative electrode tab 125 for connection to a negative electrode terminal 136.

The positive electrode tabs 130 are joined to each other at the positive electrode terminal 131, and are joined to each other together with the positive electrode terminal 131 by ultrasonic welding or the like, and the negative electrode tabs 125 are joined to each other at the negative electrode terminal 136, and are joined to each other together with the negative electrode terminal 136 by ultrasonic welding or the like. One end of the positive electrode terminal 131 is drawn out of the flexible film 140, and one end of the negative electrode terminal 136 is also drawn out of the flexible film 140.

An insulating member may be formed at the boundary portion 124 between the coated portion (coated region 11) (positive electrode active material layer 122) of the positive electrode active material and the non-coated region 12 as needed, and the insulating member may be formed not only at the boundary portion 124 but also in the vicinity of the boundary portion between the positive electrode tab 130 and the positive electrode active material.

Similarly, the coated portion of the negative electrode active material (negative electrode active material layer 127) and the boundary portion 129 of the non-coated region may be formed as an insulating member as necessary, and may be formed in the vicinity of the boundary portion between the negative electrode tab 125 and the negative electrode active material.

In general, the outer dimension of the anode active material layer 127 is larger than the outer dimension of the cathode active material layer 122 and smaller than the outer dimension of the spacer 120.

(nonaqueous electrolyte solution containing lithium salt)

The nonaqueous electrolytic solution containing a lithium salt used in the present embodiment can be appropriately selected from known ones depending on the kind of the electrode active material, the application of the lithium ion battery, and the like.

Specific examples of the lithium salt include L iClO₄、LiBF₆、LiPF₆、LiCF₃SO₃、LiCF₃CO₂、LiAsF₆、LiSbF₆、LiB₁₀Cl₁₀、LiAlCl₄、LiCl、LiBr、LiB(C₂H₅)₄、CF₃SO₃Li、CH₃SO₃Li、LiC₄F₉SO₃、Li(CF₃SO₂)₂N, lithium lower fatty acid carboxylate, and the like.

The solvent for dissolving the lithium salt is not particularly limited as long as it is a solvent generally used as a liquid for dissolving the electrolyte, and examples thereof include carbonates such as Ethylene Carbonate (EC), Propylene Carbonate (PC), Butylene Carbonate (BC), dimethyl carbonate (DMC), Ethyl Methyl Carbonate (EMC), diethyl carbonate (DEC), ethyl methyl carbonate (MEC), and Vinylene Carbonate (VC); lactones such as γ -butyrolactone and γ -valerolactone; ethers such as trimethoxymethane, 1, 2-dimethoxyethane, diethyl ether, tetrahydrofuran, and 2-methyltetrahydrofuran; sulfoxides such as dimethyl sulfoxide; oxolanes such as 1, 3-dioxolane and 4-methyl-1, 3-dioxolane; nitrogen-containing solvents such as acetonitrile, nitromethane, formamide, and dimethylformamide; organic acid esters such as methyl formate, methyl acetate, ethyl acetate, butyl acetate, methyl propionate, and ethyl propionate; phosphoric acid triesters, diethylene glycol dimethyl ethers; triethylene glycol dimethyl ethers; sulfolanes such as sulfolane and methylsulfolane; oxazolidinones such as 3-methyl-2-oxazolidinone; sultones such as 1, 3-propane sultone, 1, 4-butane sultone, and naphthalene sultone. These may be used alone or in combination of two or more.

(Container)

In the present embodiment, a known member can be used for the container, and the flexible film 140 is preferably used from the viewpoint of weight reduction of the battery. As the flexible film 140, a flexible film in which a resin layer is provided on the front and back surfaces of a metal layer serving as a base material can be used. The metal layer may be selected from those having barrier properties against leakage of the electrolyte solution and entry of moisture from the outside, and aluminum, stainless steel, or the like may be used. The exterior body is formed by providing a heat-fusible resin layer such as modified polyolefin on at least one surface of the metal layer, so that the heat-fusible resin layers of the flexible films 140 face each other with the battery element interposed therebetween, and heat-fusing the periphery of the portion accommodating the battery element. A resin layer such as a nylon film or a polyester film may be provided on the surface of the outer package body on the side opposite to the side on which the heat-fusible resin layer is formed.

(terminal)

In the present embodiment, the positive electrode terminal 131 may be made of aluminum or an aluminum alloy, and the negative electrode terminal 136 may be made of copper or a copper alloy, or a nickel-plated terminal thereof. The terminals may be drawn out of the container, and a heat-fusible resin may be provided in advance at portions of the terminals located at portions where the periphery of the outer package is heat-fused.

(insulating Member)

When the

boundary portions

124 and 129 between the coated portion and the non-coated region of the active material are formed as insulating members, polyimide, glass fiber, polyester, polypropylene, or a member including any of these may be used. These members are heat-welded to the

boundary portions

124 and 129, or a gel-like resin is applied to the

boundary portions

124 and 129 and dried, whereby an insulating member can be formed.

(spacer)

The spacer 120 according to the present embodiment preferably includes a resin layer containing a heat-resistant resin as a main component.

Here, the resin layer is formed of a heat-resistant resin as a main component. Here, the "main component" means a proportion of 50% by mass or more, preferably 70% by mass or more, more preferably 90% by mass or more, and may be 100% by mass in the resin layer.

The resin layer constituting the spacer 120 according to the present embodiment may be a single layer, or two or more layers.

Examples of the heat-resistant resin forming the resin layer include one or more selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, m-phenylene terephthalate, poly (m-phenylene terephthalate), polycarbonate, polyester carbonate, aliphatic polyamide, wholly aromatic polyamide, semi-aromatic polyamide, wholly aromatic polyester, polyphenylene sulfide, poly (p-phenylene benzobisoxazole), polyimide, polyarylate, polyether imide, polyamideimide, polyacetal, polyether ether ketone, polysulfone, polyether sulfone, fluorine-based resin, polyether nitrile, and modified polyphenylene ether.

Among these, from the viewpoint of excellent balance among heat resistance, mechanical strength, stretchability, price, and the like, one or more selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, aliphatic polyamide, wholly aromatic polyamide, semi-aromatic polyamide, and wholly aromatic polyester is preferable, one or more selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate, aliphatic polyamide, wholly aromatic polyamide, and semi-aromatic polyamide is more preferable, one or more selected from the group consisting of polyethylene terephthalate and wholly aromatic polyamide is further preferable, and polyethylene terephthalate is more preferable.

The resin layer constituting the spacer 120 according to the present embodiment is preferably a porous resin layer. Thus, in the case where an abnormal current is generated in the lithium ion battery or the battery temperature rises, the micropores of the porous resin layer are blocked to interrupt the flow of current, and thermal runaway of the battery can be avoided.

The porosity of the porous resin layer is preferably 20% or more and 80% or less, more preferably 30% or more and 70% or less, and particularly preferably 40% or more and 60% or less, from the viewpoint of balance between mechanical strength and lithium ion conductivity.

The porosity can be determined by the following equation.

＝{1-Ws/(ds·ts)}×100

Here, the following: porosity (%), Ws: weight per unit area (g/m)²) Ds: true density (g/cm)³) Ts: film thickness (. mu.m).

The planar shape of the spacer 120 according to the present embodiment is not particularly limited, and may be appropriately selected according to the shapes of the electrode and the current collector, and may be, for example, a rectangular shape.

The thickness of the spacer 120 according to the present embodiment is preferably 5 μm or more and 50 μm or less from the viewpoint of balance between mechanical strength and lithium ion conductivity.

As described above, according to the present embodiment, a battery can be manufactured using the current collector electrode sheet 10 manufactured by the manufacturing method of the above embodiment.

According to the method for producing an electrode of the present invention, it is possible to assemble an electrochemical device such as a battery in which generation of burrs on a current collector occurring when an electrode is produced through a step of forming an active material layer on a current collector having a small thickness such as a current collector layer, drying the active material layer, compressing the dried active material layer, and cutting the dried active material layer, and thereby provide an electrochemical device such as a battery having excellent characteristics.

While the embodiments of the present invention have been described above with reference to the drawings, these are illustrative of the present invention, and various configurations other than those described above may be employed.

The present invention is not limited to the above-described embodiments, and modifications, improvements, and the like are included within a range in which the object of the present invention can be achieved.

Examples

Specific examples will be described in more detail below.

(example 1)

As the positive electrode active material, a 50% cumulative particle diameter (D) obtained from the particle size distribution measurement value was mixed₅₀) 8 μm, likewise 90% cumulative particle diameter (D)₉₀) L i (Ni) at 12 μm_0.6Co_0.2Mn_0.2)O₂The resultant mixture was mixed with 94.8% by mass, 2.5% by mass of a graphite material as a conductive auxiliary material and 2.7% by mass of polyvinylidene fluoride as a binder to prepare a positive electrode slurry. Using a type B viscometer (Brookfield, rotational viscometer), the shear rate was 3.4s at 25 ℃^-1The viscosity of the slurry thus prepared was measured under the conditions (1) to obtain 4850 mPas. The solid content concentration of the slurry was 66 mass％。

The total length 1 of the coating region of the leading end portion, the central portion and the terminal end portion was set to 222mm, the rotation speed v of the roll was set to 30m/min, and the gap (gap) d between the metal foil and the dies of the leading end portion 301 and the central portion 302 was set to₂The length x of the starting end portion 301 and the central portion 302 is set to 130 μm₂-x₀The gap (clearance) d between the die and the metal foil at the terminal end 303 was set to 202mm₃The thickness was set to 80 μm. Then, the weight per unit area was adjusted to 23.5mg/cm²The slurry is discharged from the die, and intermittently applied onto the collector foil surfaces (9a, 9b) of a strip-shaped aluminum foil having a thickness of 12 μm, which is moved over a backup roll 26, so that the application regions 11 and the non-application regions 12 are alternately formed in the winding direction Dx of the foil 9.

Further, the slurry containing the active material and the like applied to the aluminum foil 9 is dried and solidified in a drying furnace (dryer 25) provided next. Further, the front end of the application region 11 applied to the front surface 9a of the back surface 9b on which the slurry was applied in the application step was detected, and the slurry application, drying and curing were performed in the same manner while controlling so that the variation in the front end of the application region 11 of the back surface 9b was 1mm or less, thereby obtaining the collector tab 10 on which the slurry was applied to both surfaces of the aluminum foil 9. In the slurry coating step, the amount of variation in the length of the coated region 11 in the same aluminum foil roll is adjusted to 2mm or less. A part of the obtained current collector electrode sheet 10 was extracted, and the maximum length of the tail portion was measured to be 0.5 mm.

Next, the current collector electrode sheet 10 intermittently applied with the slurry was passed between the compression rolls having the gap width by using a compression apparatus 40 having two compression rolls 50 with a roll radius of 250mm as a pair, and was set at a winding tension of 230N, and was moved on a backup roll 51 at a rotation speed of 60 m/min, thereby performing compression. At this time, the compression pressure was adjusted so that the linear pressure in the application region of the active material slurry was 1.8t/cm, the gap between the upper and lower compression rollers 50 was 0.4mm on average, and the roller compression pressure was 19MPa on average. The average thickness of the single-sided active material layer of a part of the obtained current collector electrode sheet 10 was extracted to 65 μm, and was constant until the end of application. Further, it was confirmed that no slurry was adhered to the non-application region 12 by using the appearance inspection machine attached to the compression apparatus 40.

Next, the current collector electrode sheet 10 after the pressure compression described above is passed between the blades, set so that the winding tension becomes constant, and moved at a constant speed on the support roller 63, thereby performing cutting, using the cutting device 60 having the shearing blade 61 at the upper portion and the combining blade 62 at the lower portion. A part of the obtained cut sheet was extracted, and it was confirmed that there was a burr at the trailing end after the passive self-cutting process.

The obtained evaluation results are shown in table 1.

[ Table 1]

TABLE 1 evaluation results

Regarding the insufficient film thickness at the end of the application region, the adhesion of the slurry to the non-application region, and the generation of burrs, 10 samples were observed, and even if 1 sample was generated, the occurrence was considered.

(examples 2 to 6 and comparative examples 1 to 6)

Except for the interval (gap) d between the die at the end and the metal foil₃And the total length x of the starting end and the central part₂-x₀Except for the change to the values shown in table 1, the surface of the collector foil was intermittently coated with the slurry in the same manner as in example 1 so that the coated regions 11 and the non-coated regions 12 were alternately formed in the direction Dx of winding the foil, and the maximum length measurement of the trailing portion, the presence or absence of the adhesion of the slurry to the non-coated region, the presence or absence of the burr of the trailing portion after the passive self-cutting step, and the like were performed, and the presence or absence of the film thickness deficiency at the end portion of the coated region after the coating and drying was confirmed. The results are shown in Table 1.

The present invention has been described above with reference to the embodiments and examples, but the present invention is not limited to the embodiments and examples. The structure and details of the present invention may be variously modified within the scope of the present invention as will be understood by those skilled in the art.

Hereinafter, reference examples are attached.

1. A current collector electrode sheet in which an active material is coated on both surfaces of a sheet-like current collector layer,

2. A method for manufacturing a collector electrode sheet by discharging a slurry containing an active material from a die head to both surfaces of a sheet-like collector layer, intermittently applying the slurry, and drying the slurry to alternately form a coating region and a non-coating region of the slurry in a winding direction of the collector layer,

3. The method for manufacturing a collector electrode sheet according to claim 2, wherein,

the distance between the die and the current collector layer in the step of forming the terminal end portion of the coating region is 50% to 90% of the distance between the die and the current collector layer in the step of forming the central portion of the coating region.

4. The method for manufacturing a collector electrode sheet according to claim 3, wherein,

the distance between the die and the current collector layer in the step of forming the terminal end portion of the coating region is 50% to 70% of the distance between the die and the current collector layer in the step of forming the central portion of the coating region.

5. The method for manufacturing a collector electrode sheet according to any one of claims 2 to 4, wherein,

when the application of the slurry is completed to a point of 88% to 93% of the entire length of the application region in each application region formed by intermittently applying the slurry, a treatment of narrowing the distance between the die and the collector layer is performed in order to shift from the step of forming the central portion of the application region to the step of forming the terminal portion of the application region.

6. The method for manufacturing a collector electrode sheet according to any one of claims 2 to 5, wherein,

the change in the spacing of the die from the current collector layer is performed by movement of the die.

7. A collector electrode sheet produced by the method for producing a collector electrode sheet according to any one of claims 2 to 6.

8. A method for manufacturing a battery, comprising the steps of: forming a positive electrode active material layer on both surfaces of a sheet-like current collector layer to form a positive electrode current collector electrode sheet; forming a negative electrode active material layer on both surfaces of a sheet-like current collector layer to form a negative electrode current collector tab; cutting the positive electrode collector tab and the negative electrode collector tab into predetermined sizes, thereby forming a positive electrode and a negative electrode, respectively; a step of laminating the positive electrode and the negative electrode with a separator interposed therebetween,

wherein either or both of the step of forming the positive electrode collector tab and the step of forming the negative electrode collector tab include the respective steps of the method for manufacturing a collector tab according to any one of claims 2 to 6.

9. A battery comprising at least a positive electrode, a negative electrode and an electrolyte,

either or both of the positive electrode and the negative electrode are formed by cutting the current collector tab described in 1 or 7 into a predetermined size.

The present application claims priority based on japanese application No. 2017-234647, filed on 6.12.2017, and the entire disclosure thereof is incorporated herein by reference.

Claims

3. The method for manufacturing a collector electrode sheet according to claim 2,

4. The method for manufacturing a collector electrode sheet according to claim 3,

5. The method for manufacturing a collector electrode sheet according to any one of claims 2 to 4,

6. The method for manufacturing a collector electrode sheet according to any one of claims 2 to 5,

either or both of the positive electrode and the negative electrode are formed by cutting the current collector tab according to claim 1 or 7 into a predetermined size.