JP2016100067A - Method of manufacturing electrode for lithium ion battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing an electrode for a lithium ion battery in which the basis weight amount accuracy of a powder layer at both the end portions in the width direction of the powder layer can be kept to be high.SOLUTION: A method of manufacturing an electrode for a lithium ion battery comprises a coating step of applying binding material coating liquid onto the surface of a base material 12, a supply step of supplying powder 16 containing electrode active material onto the surface of the base material on which the binding material coating liquid is applied, a control step of controlling the basis weight amount of the powder on the base material surface, a removing step of removing the powder supplied out of the set width corresponding to the width of the electrode for the lithium ion battery after the basis weight of the powder is controlled in the control step, and a forming step of pressing the powder on the base material surface by using a pair of press rolls 22A, 22B after the powder supplied out of the set width is removed by the removing step to form a powder layer 24.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for producing an electrode for a lithium ion battery, in which a powder containing an electrode active material or the like is compression molded to produce an electrode for a lithium ion battery.

  The demand for lithium-ion batteries that are compact and lightweight, have high energy density, and can be repeatedly charged and discharged is expected to increase in the future from the environmental viewpoint. Lithium-ion batteries are used in the fields of mobile phones and notebook PCs because of their high energy density, but with the expansion and development of applications, further improvements in performance such as lower resistance and larger capacity Is required.

  The electrode for a lithium ion battery can be obtained as an electrode sheet. For example, Patent Document 1 discloses that after a binder is applied to a base material, powder is dispersed to form a powder layer on the surface of the base material, and the base material is passed between a pair of press rolls. A method for manufacturing a lithium ion secondary battery is disclosed in which an electrode sheet is obtained by continuously compression-molding a powder layer on the surface of the battery. Patent Document 2 discloses a method of manufacturing a lithium ion secondary battery in which an electrode material is obtained by supplying an electrode material onto a press roll and compression molding.

JP 2014-078497 A Japanese Patent No. 4876478

  By the way, when manufacturing an electrode sheet using the above-described method for manufacturing a lithium ion secondary battery, the powder slides down from the press roll, and the powder flows in the width direction and enters the end of the powder layer. As a result, unevenness occurs. For this reason, there has been a problem that both end portions in the width direction of the powder layer have poor basis weight.

  An object of the present invention is to provide a method for producing an electrode for a lithium ion battery that can maintain a high basis weight accuracy of the powder layer at both ends in the width direction of the powder layer.

  As a result of intensive studies, the present inventors achieved the above object by removing the powder supplied outside the set width corresponding to the width of the electrode for the lithium ion battery immediately after the basis weight of the powder was controlled. The present inventors have found that this can be done and have completed the present invention.

That is, according to the present invention,
(1) An application step of applying a binder coating liquid to the substrate surface, a supply step of supplying a powder containing an electrode active material to the substrate surface coated with the binder coating solution, and the base A control step for controlling the basis weight of the powder on the surface of the material, and after the basis weight of the powder is controlled by the control step, the powder supplied outside the set width corresponding to the width of the electrode for a lithium ion battery A removing step of removing the powder, and after the powder supplied outside the set width is removed by the removing step, the powder on the surface of the substrate is pressed using a pair of pressing rolls. A process for forming a powder layer, and a method for producing an electrode for a lithium ion battery, comprising:

(2) The lithium according to (1), wherein the removing step scrapes off the powder supplied outside the set width using a pair of jigs arranged on both outer sides of the set width. A method for producing an ion battery electrode,

(3) In the removing step, the powder supplied outside the set width is sucked using a suction machine having suction ports arranged on both outer sides of the set width (1). A method for producing the lithium ion battery electrode according to claim
Is provided.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the electrode for lithium ion batteries which can maintain high the amount of areal weight of the powder layer in the width direction both ends of a powder layer can be provided.

It is a figure which shows the outline of the powder molding apparatus which concerns on the 1st Embodiment of this invention. It is a figure for explaining composition and operation of a pair of jigs concerning a 1st embodiment of the present invention. It is a figure for demonstrating the structure and operation | movement of a suction machine which concern on the 2nd Embodiment of this invention.

  Hereinafter, a method for manufacturing an electrode for a lithium ion battery according to a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing an outline of a powder molding apparatus 2 used for manufacturing a lithium ion battery electrode according to a first embodiment of the present invention. As shown in FIG. 1, the powder molding apparatus 2 includes a hopper 18 that contains the powder 16, a squeegee member 20 that controls the basis weight of the powder 16 that is supplied from the hopper 18 to the surface of the substrate 12, lithium ions A pair of jigs 4A and 4B for removing the powder 16 supplied to both ends in the width direction of the battery electrode, and a pair of press rolls 22A and 22B for pressing the powder 16 supplied to the surface of the substrate 12 are provided. ing.

  The squeegee member 20 has a cylindrical shape and is disposed on the downstream side of the hopper 18 and on the upstream side of the pair of press rolls 22A and 22B. The rotation axis of the squeegee member 20 is parallel to the rotation axes of the pair of press rolls 22A and 22B.

  FIG. 2 is a diagram for explaining the configuration and operation of the pair of jigs 4A and 4B. In addition, this figure is the figure which looked at the powder molding apparatus 2 shown in FIG. 1 from the right direction, and illustration of the hopper 18 and the roller 22B for a press is abbreviate | omitted. Further, the powder 16 shown in FIG. 2 is the one after being squeezed by the squeegee member 20, and the powder layer 24 shown in FIG. 2 is obtained by pressing the powder 16 with the pressing roller 22A and the pressing roller 22B. Later.

  As shown in FIG. 2, the jig 4 </ b> A has a wedge shape, and is disposed immediately after the squeegee member 20 and on the left outer side of the set width D corresponding to the width of the lithium ion battery electrode. The jig 4A scrapes off the powder 16 supplied to the left outer side of the set width D from the base material 12 by sliding it off the base material 12 along the inclined surface 4a immediately after the squeegee by the squeegee member 20. On the other hand, as shown in FIG. 2, the jig 4 </ b> B has a wedge shape, and is disposed immediately after the squeegee member 20 and on the right outside of the set width D. Immediately after the squeegee by the squeegee member 20, the jig 4 </ b> B scrapes off the powder 16 supplied to the right outside of the set width D from the substrate 12 by sliding it off the substrate 12 along the inclined surface 4 b.

  When manufacturing an electrode sheet as an electrode for a lithium ion battery using the powder molding apparatus 2 according to the first embodiment, first, the surface of the base material 12 by a binder coating liquid coating apparatus (not shown). The binder coating liquid is applied within the set width D. Next, the powder 16 is supplied from the hopper 18 to the surface of the base material 12 to which the binder coating liquid has been applied. Then, the basis weight of the powder 16 supplied to the surface of the substrate 12 by the squeegee member 20 is controlled, and the powder 16 supplied outside the set width D is scraped off by the pair of jigs 4A and 4B. The powder layer 24 is formed by being pressed by passing between the press rolls 22A and 22B. Thereby, an electrode sheet in which the powder layer 24 is compression-molded on the surface of the substrate 12 is manufactured.

  According to the method for manufacturing an electrode for a lithium ion battery according to the first embodiment, immediately after the powder 16 supplied to the outside of the set width D using the pair of jigs 4A and 4B is squeezed by the squeegee member 20. Scrape off the outside of the substrate 12. Therefore, after the squeegee by the squeegee member 20, the powder 16 outside the set width D slides into the set width D and can be prevented from being pressed by the pair of press rolls 22A and 22B. That is, it is possible to prevent a portion with a large basis weight from being formed at both ends in the width direction of the set width D when the slid down powder 16 enters the set width D.

  Next, a method for manufacturing an electrode for a lithium ion battery according to a second embodiment of the present invention will be described with reference to the drawings. The powder molding apparatus used for manufacturing the electrode for a lithium ion battery according to the second embodiment includes a suction machine instead of the pair of jigs 4A and 4B according to the first embodiment. Specifically, in the powder molding apparatus according to the second embodiment, the pair of jigs 4A and 4B included in the powder molding apparatus 2 shown in FIG. 1 is removed, and the pair of jigs 4A and 4B are arranged. A suction machine is placed at the position. FIG. 3 is a diagram for explaining the configuration and operation of the suction device 8 according to the second embodiment. This figure is the powder molding apparatus 2 shown in FIG. 1 and is a view of the powder molding apparatus 2 provided with a suction device 8 in place of the pair of jigs 4A and 4B as viewed from the right side. 18 and the pressing roller 22B are not shown. Further, the powder 16 shown in FIG. 3 is obtained after being squeezed by the squeegee member 20, and the powder layer 24 shown in FIG. 3 is obtained by pressing the powder 16 with the pressing roller 22A and the pressing roller 22B. Later. In addition, regarding the powder molding apparatus used in the method for manufacturing an electrode for a lithium ion battery according to the second embodiment, the same components as those of the powder molding apparatus 2 shown in FIG. The description is omitted.

  The suction device 8 is disposed immediately after the squeegee member 20 and upstream of the pair of press rolls 22A and 22B. As shown in FIG. 3, the suction machine 8 has a suction port 9 a disposed on the left outer side of the set width D and a suction 9 b disposed on the right outer side of the installation width D. The suction machine 8 removes the powder 16 supplied to the left outer side of the set width D from the base material 12 by suction from the suction port 9a immediately after the squeegee by the squeegee member 20. Further, immediately after the squeegee by the squeegee member 20, the suction device 8 removes the powder 16 supplied to the right outside of the set width D from the base 12 by sucking it from the suction port 9b.

  When manufacturing an electrode sheet as an electrode for a lithium ion battery using the powder molding apparatus 2 according to the second embodiment, first, the surface of the base material 12 by a binder coating liquid coating apparatus (not shown). The binder coating liquid is applied within the set width D. Next, the powder 16 is supplied from the hopper 18 to the surface of the base material 12 to which the binder coating liquid has been applied. Then, immediately after the basis weight of the powder 16 supplied to the surface of the base material 12 is controlled by the squeegee member 20, the powder 16 supplied outside the set width D is sucked by the suction machine 8. Then, the powder 16 within the set width D is pressed by passing between the pair of press rolls 22A and 22B, whereby the powder layer 24 is formed. Thereby, an electrode sheet in which the powder layer 24 is compression-molded on the surface of the substrate 12 is manufactured.

  According to the method for manufacturing an electrode for a lithium ion battery according to the second embodiment, the base material immediately after the powder 16 supplied to the outside of the set width D using the suction device 8 is squeezed by the squeegee member 20. Aspirate from 12. Therefore, after the squeegee by the squeegee member 20, the powder 16 outside the set width D slides into the set width D and can be prevented from being pressed by the pair of press rolls 22A and 22B. That is, it is possible to prevent a portion with a large basis weight from being formed at both ends in the width direction of the set width D when the slid down powder 16 enters the set width D.

  In each of the above-described embodiments, the substrate 12 may be a thin film substrate, and usually has a thickness of 1 μm to 1000 μm, preferably 5 μm to 800 μm. As the base material 12, metal foil or carbon such as aluminum, platinum, nickel, tantalum, titanium, stainless steel, copper, and other alloys, conductive polymer, paper, natural fiber, polymer fiber, fabric, polymer resin A film etc. are mentioned, It can select suitably according to the objective. Examples of the polymer resin film include polyester resin films such as polyethylene terephthalate and polyethylene naphthalate, plastic films and sheets including polyimide, polypropylene, polyphenylene sulfide, polyvinyl chloride, aramid film, PEN, PEEK, and the like. It is done.

  Among these, when manufacturing an electrode sheet for a lithium ion battery electrode, a metal foil, a carbon film, or a conductive polymer film can be used as the substrate 12, and a metal is preferably used. Among these, it is preferable to use copper, aluminum, or an aluminum alloy in terms of conductivity and voltage resistance. Further, the surface of the base material 12 may be subjected to treatment such as coating treatment, drilling, buffing, sandblasting and / or etching.

  The binder coating liquid is an SBR aqueous dispersion, and the concentration of SBR is 10.0 to 40 wt%. The glass transition temperature of SBR is in the range of −50 ° C. to 30 ° C. The binder coating liquid may contain a thickener and a surfactant in order to adjust the viscosity and wettability of the coating liquid. Known thickeners and surfactants can be used. In addition to SBR, water-based polyacrylic acid (PAA), organic solvent-based polyvinylidene fluoride (PVDF), or the like may be used as the binder.

  Examples of the powder 16 accommodated in the hopper 18 include composite particles containing an electrode active material. The composite particles include an electrode active material and a binder, and may include other dispersants, conductive materials, and additives as necessary.

  When the composite particles are used as an electrode material for a lithium ion battery, examples of the positive electrode active material include metal oxides capable of reversibly doping and dedoping lithium ions. Examples of the metal oxide include lithium cobaltate, lithium nickelate, lithium manganate, and lithium iron phosphate. In addition, the positive electrode active material illustrated above may be used independently according to a use, and may be used in mixture of multiple types.

  The active material of the negative electrode as the counter electrode of the positive electrode for lithium ion batteries includes graphitizable carbon, non-graphitizable carbon, low crystalline carbon such as pyrolytic carbon (amorphous carbon), graphite (natural graphite) , Artificial graphite), alloy materials such as tin and silicon, oxides such as silicon oxide, tin oxide, and lithium titanate. In addition, the electrode active material illustrated above may be used independently according to a use, and may be used in mixture of multiple types.

  The shape of the electrode active material for the lithium ion battery electrode is preferably a granulated particle. When the shape of the particles is spherical, a higher density electrode can be formed during electrode molding.

  The volume average particle diameter of the electrode active material for a lithium ion battery electrode is usually 0.1 to 100 μm, preferably 0.5 to 50 μm, more preferably 0.8 to 30 μm for both the positive electrode and the negative electrode.

  The binder used for the composite particles is not particularly limited as long as it is a compound capable of binding the electrode active materials to each other. A suitable binder is a dispersion type binder having a property of being dispersed in a solvent. Examples of the dispersion-type binder include high molecular compounds such as silicon polymers, fluorine-containing polymers, conjugated diene polymers, acrylate polymers, polyimides, polyamides, polyurethanes, and preferably fluorine-containing polymers. Polymers, conjugated diene polymers and acrylate polymers, more preferably conjugated diene polymers and acrylate polymers.

  The shape of the dispersion-type binder is not particularly limited, but is preferably particulate. By being particulate, the binding property is good, and it is possible to suppress deterioration of the capacity of the manufactured electrode and deterioration due to repeated charge and discharge. Examples of the particulate binder include those in which the particles of the binder such as latex are dispersed in water, and particulates obtained by drying such a dispersion.

  The amount of the binder is such that the adhesion between the obtained electrode active material layer and the substrate can be sufficiently secured and the internal resistance can be lowered. The amount is usually 0.1 to 50 parts by weight, preferably 0.5 to 20 parts by weight, more preferably 1 to 15 parts by weight.

  As described above, a dispersant may be used for the composite particles as necessary. Specific examples of the dispersant include cellulose polymers such as carboxymethyl cellulose and methyl cellulose, and ammonium salts or alkali metal salts thereof. These dispersants can be used alone or in combination of two or more.

  As described above, a conductive material may be used for the composite particles as necessary. 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). Among these, acetylene black and ketjen black are preferable. These conductive materials can be used alone or in combination of two or more.

  The composite particles are obtained by granulating using an electrode active material, a binder, and other components such as the conductive material added as necessary, and include at least an electrode active material and a binder, Each of the above does not exist as an independent particle, but forms one particle by two or more components including an electrode active material and a binder as constituent components. Specifically, a plurality of (more preferably several to several tens) electrode active materials are formed by combining a plurality of the individual particles of the two or more components to form secondary particles. It is preferable that the particles are bound to form particles.

  The production method of the composite particles is not particularly limited, and can be produced by a known granulation method such as a fluidized bed granulation method, a spray drying granulation method, or a rolling bed granulation method.

  The volume average particle diameter of the composite particles is usually in the range of 0.1 to 1000 μm, preferably 1 to 500 μm, more preferably 30 to 250 μm, from the viewpoint of easily obtaining an electrode active material layer having a desired thickness.

  The average particle size of the composite particles is a volume average particle size calculated by measuring with a laser diffraction particle size distribution measuring device (for example, SALD-3100; manufactured by Shimadzu Corporation).

  DESCRIPTION OF SYMBOLS 2 ... Powder shaping | molding apparatus, 4A, 4B ... Jig, 8 ... Suction machine, 12 ... Base material, 16 ... Powder, 18 ... Hopper, 20 ... Squeegee member, 22A, 22B ... Press roll, 24 ... Powder layer .

Claims (3)

An application step of applying a binder coating liquid to the substrate surface;
A supply step of supplying a powder containing an electrode active material to the surface of the base material to which the binder coating liquid has been applied;
A control step of controlling the basis weight of the powder on the substrate surface;
After the basis weight of the powder is controlled by the control step, the removal step of removing the powder supplied outside the set width corresponding to the width of the lithium ion battery electrode;
Formation of forming a powder layer by pressing the powder on the surface of the base material using a pair of pressing rolls after the powder supplied outside the set width is removed by the removing step Process,
The manufacturing method of the electrode for lithium ion batteries characterized by including.   2. The lithium ion battery according to claim 1, wherein in the removing step, the powder supplied outside the set width is scraped off using a pair of jigs arranged on both outer sides of the set width. Electrode manufacturing method.   2. The lithium according to claim 1, wherein in the removing step, the powder supplied outside the set width is sucked using a suction machine having suction ports arranged on both outer sides of the set width. A method for producing an ion battery electrode.

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