JP2016115603A - Method of manufacturing electrode for lithium ion battery - Google Patents

Abstract

A method of manufacturing an electrode for a lithium ion battery having high peel strength between an active material layer and a substrate at both ends in the width direction of the active material layer is provided. A step of applying a first binder coating liquid 4 to the surface of a base material 12 corresponding to a center portion in the width direction of an active material layer, and a base material corresponding to both end portions in the width direction of the active material layer. A step of applying a second binder coating liquid 8 to the surface of 12, and a powder containing an electrode active material on the surface of the substrate 12 coated with the first binder coating liquid 4 and the second binder coating liquid 8 The active material layer 24 is formed by pressing the powder 16 supplied to the surface of the base material 12, the step of supplying the step of supplying 16, the basis weight of the powder 16 supplied to the surface of the base material 12, and the base material 12 The tack strength of the binder used for the second binder coating liquid 8 is greater than the tack strength of the binder used for the first binder coating liquid 4, or the second binder coating A method for producing an electrode for a lithium ion battery, wherein the solid content concentration of the liquid 8 is greater than the solid content concentration of the first binder coating liquid 4. [Selection] 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 an active material 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 an active material layer on the surface.

JP 2014-078497 A

  By the way, when an electrode sheet is manufactured using the above-described method for manufacturing a lithium ion secondary battery, the powder flows outward in the width direction when the base material is passed between a pair of press rolls, and the active material layer. Sagging occurs at the end of the. For this reason, both ends in the width direction of the active material layer are insufficiently pressed, and the adhesive force between the active material layer and the base material is reduced. As a result, the active material layer and the base material at both ends in the width direction of the active material layer There was a problem that the peel strength of the resin was lowered.

  The objective of this invention is providing the manufacturing method of the electrode for lithium ion batteries which can maintain the peeling strength of the active material layer and a base material in the width direction both ends of an active material layer high.

  As a result of intensive studies, the present inventors applied a first binder coating liquid to the surface of the base material corresponding to the center in the width direction of the electrode active material layer for lithium ion batteries, and the electrode active material for lithium ion batteries To find out that the above object can be achieved by applying a second binder coating liquid different from the first binder coating liquid to the substrate surface corresponding to both ends in the width direction of the layer, and to complete the present invention. It came.

That is, according to the present invention,
(1) a first application step of applying a first binder coating liquid on the surface of a base material corresponding to a central portion in the width direction of the electrode active material layer for a lithium ion battery, and the electrode active material layer for the lithium ion battery A second application step of applying a second binder coating liquid different from the first binder coating liquid to the substrate surface corresponding to both ends in the width direction; the first binder coating liquid and the first binder coating liquid; A supply step of supplying a powder containing an electrode active material to the surface of the base material coated with two binder coating liquid; a control step of controlling the basis weight of the powder supplied to the surface of the base material; A step of forming an active material layer by pressing the powder supplied to the surface of the substrate, and the tack strength of the binder used in the second binder coating liquid is the first It is larger than the tack strength of the binder used in the binder coating liquid, or the solid content concentration of the second binder coating liquid is Method for producing a lithium ion battery electrode, wherein the serial greater than the solid concentration of the first binder coating liquid,

(2) The tack strength of the binder used in the second binder coating liquid is 1.5 times or more the tack strength of the binder used in the first binder coating liquid. (1) The manufacturing method of the electrode for lithium ion batteries as described in

(3) The solid content concentration of the second binder coating liquid is 1.3 times or more the solid content concentration of the first binder coating liquid (1) or (2) A method for producing an electrode for a lithium ion battery,

(4) The width of the end in the width direction of the electrode active material layer for the lithium ion battery is 0.5% or more and 5% or less with respect to the width of the electrode active material layer for the lithium ion battery. The method for producing an electrode for a lithium ion battery according to any one of (1) to (3),
Is provided.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the electrode for lithium ion batteries which can maintain the peeling strength of the active material and base material in the width direction both ends of an active material layer high can be provided.

It is a figure which shows the outline of the powder molding apparatus which concerns on embodiment of this invention. It is a figure for demonstrating the area | region where the 1st binder coating liquid and 2nd binder coating liquid which concern on embodiment of this invention are apply | coated to the base-material surface. It is a graph which shows the fabric weight of the powder with respect to the active material layer width | variety at the time of the 1st binder coating liquid being apply | coated to the surface of a base material. It is a graph which shows the fabric weight of the powder with respect to the active material layer width | variety at the time of the 1st binder coating liquid and the 2nd binder coating liquid being apply | coated to the surface of a base material. It is a figure for demonstrating the other area | region where the 1st binder coating liquid and 2nd binder coating liquid which concern on embodiment of this invention are apply | coated to the base-material surface.

  Hereinafter, a method for manufacturing an electrode for a lithium ion battery according to an 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 an embodiment of the present invention. As shown in FIG. 1, the powder molding apparatus 2 includes a first application unit 6 that applies a first binder coating solution 4, a second application unit 10 that applies a second binder coating solution 8, and a base material. Conveying rollers 14 </ b> A and 14 </ b> B that convey the powder 12, a hopper 18 that contains the powder 16, a squeegee member 20 that controls the basis weight of the powder 16 supplied from the hopper 18 to the surface of the substrate 12, and the surface of the substrate 12 Are provided with a pair of pressing rolls 22A and 22B for pressing the powder 16 to be supplied.

  The first application unit 6 includes a first storage tank 6a for storing the first binder coating solution 4 and a region 12a on the surface of the substrate 12 corresponding to the center portion in the width direction of the electrode active material layer for a lithium ion battery (see FIG. 2) is provided with a first gravure roll 6b for applying the first binder coating liquid 4. The width of the first gravure roll 6b is set to the width A of the region 12a (see FIG. 2) in order to apply the first binder coating liquid 4 to the region 12a of the substrate 12.

  The 2nd application part 10 respond | corresponds to the width direction both ends of the 2nd storage tank 10a which stores the 2nd binder coating liquid 8 different from the 1st binder coating liquid 4, and the electrode active material layer for lithium ion batteries. A second gravure roll 10b for applying the second binder coating liquid 8 to the regions 12b and 12c (see FIG. 2) on the surface of the substrate 12 is provided. The width of the second gravure roll 10b is set to the width A + B + C (see FIG. 2) of the regions 12a, 12b and 12c of the substrate 12 corresponding to the width of the active material layer for a lithium ion battery. Moreover, the roll diameter of the width direction both ends of the 2nd gravure roll 10b is larger than the roll diameter of a center part, and the width | variety of the part with a large roll diameter of one edge part is the width B of the area | region 12b of the base material 12 (refer FIG. 2). ), The width of the portion having the larger roll diameter at the other end is set to the width C of the region 12c of the substrate 12 (see FIG. 2). This is because the second binder coating liquid 8 is not applied to the region 12a of the substrate 12 and is applied only to the regions 12b and 12c.

  The squeegee member 20 has a cylindrical shape, and is disposed downstream of the hopper 18 and upstream 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.

  When manufacturing an electrode sheet as an electrode for a lithium ion battery using this powder molding apparatus 2, first, as shown in FIG. 2, it corresponds to the center in the width direction of the electrode active material layer for the lithium ion battery. The first binder coating liquid 4 stored in the first storage tank 6 a of the first application unit 6 is applied to the region 12 a of the base 12. Specifically, the first binder coating liquid 4 is applied by rotating the first gravure roll 6b of the first coating section 6 immersed in the first binder coating liquid 4 against the region 12a of the substrate 12 and rotating. To do. Next, as shown in FIG. 2, it is stored in the second storage tank 10a of the second application unit 10 in the regions 12b and 12c of the base material 12 corresponding to both ends in the width direction of the electrode active material layer for the lithium ion battery. The second binder coating liquid 8 is applied. Specifically, the second binder coating liquid is obtained by rotating the second gravure roll 10b of the second application unit 10 immersed in the second binder coating liquid 8 against the regions 12b and 12c on the surface of the base 12 and rotating. 8 is applied. The base material 12 on which the first binder coating liquid 4 is applied to the area 12a and the second binder coating liquid 8 is applied to the areas 12b and 12c reaches the hopper 18 via the transport rollers 14A and 14B. Powder 16 is supplied to the surface of the substrate 12. The basis weight of the powder 16 supplied to the surface of the substrate 12 is controlled by the squeegee member 20 and is pressed by passing between a pair of press rolls 22A and 22B, whereby an active material layer 24 is formed. . Thereby, the electrode sheet by which the active material layer 24 was compression-molded on the surface of the base material 12 is manufactured.

  Here, 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 first binder coating liquid 4 is not particularly limited as long as it is a compound capable of binding the powder containing the active material and the base material to each other. The first binder coating liquid 4 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. Examples of the binder include SBR aqueous dispersion, acrylate polymer aqueous dispersion, aqueous polyacrylic acid (PAA), and organic solvent-based polyvinylidene fluoride (PVDF).

  The second binder coating liquid 8 can be selected from compounds capable of binding a powder containing an active material and a substrate to each other in the same manner as the first binder coating liquid 4 and the first binder coating liquid 8. The binder coating liquid 4 is a binder coating liquid in which at least one of the binder type, the tack strength of the binder, the solid content concentration, and the like is different.

  The first binder coating liquid 4 and the second binder coating liquid 8 are different binder coating liquids, and the tack strength of the binder used for the second binder coating liquid 8 is the first binder. It is preferably larger than the tack strength of the binder used in the binder coating liquid 4 and more than 1.5 times the tack strength of the binder contained in the first binder coating liquid 4. If the tack strength of the binder increases, the basis weight of the powder deposited on the binder coating liquid increases, the density of the powder increases, and the adhesive strength of the powder to the base material increases. It is.

  Alternatively, the solid content concentration of the second binder coating solution 8 is greater than the solid content concentration of the first binder coating solution 4 and is 1.3 times or more the solid content concentration of the first binder coating solution 4. It is preferable that When the solid content concentration of the binder coating liquid increases, the basis weight of the powder deposited on the binder coating liquid increases, the density of the powder increases, and the adhesion strength of the powder to the substrate increases. Because it grows. The tack strength of the binder used for the second binder coating liquid 8 is greater than the tack strength of the binder used for the first binder coating liquid 4, and the second binder coating liquid 8 You may use the 2nd binder coating liquid 8 whose solid content concentration is larger than the solid content concentration of the 1st binder coating liquid 4. FIG.

  FIG. 3 is a graph showing the basis weight of the powder 16 with respect to the width of the active material layer when only the first binder coating solution 4 is applied to the regions 12a, 12b, and 12c of the substrate 12. FIG. 4 shows the powder with respect to the active material layer width when the first binder coating solution 4 is applied to the region 12a of the substrate 12 and the second binder coating solution 8 is applied to the regions 12b and 12c of the substrate 12. 16 is a graph showing 16 basis weights. When only the first binder coating solution 4 is applied to the regions 12a, 12b, and 12c of the base material 12, as shown in the graph of FIG. 3, the basis weight of the powder 16 at both ends in the width direction of the active material layer Is smaller than the basis weight of the powder 16 in the central portion in the width direction. On the other hand, when the first binder coating solution 4 is applied to the region 12a of the substrate 12 and the second binder coating solution 8 is applied to the regions 12b and 12c of the substrate 12, as shown in the graph of FIG. Moreover, the basis weight of the powder 16 at both ends in the width direction of the active material layer is larger than the basis weight of the powder 16 at the center in the width direction. Therefore, since the adhesive strength of the powder 16 at both ends in the width direction of the active material layer can be increased, it is possible to prevent the active material layers 24 at both ends from peeling from the substrate 12.

  On the other hand, when only the second binder coating liquid 8 is applied to the regions 12 a, 12 b, and 12 c of the substrate 12, the electrical resistance increases and the basis weight of the powder 16 becomes excessive, and passes through the squeegee member 20. At this time, since excessive shearing force is applied to the powder 16, problems such as tearing of the base material 12 may occur. Moreover, the increase in electrical resistance is suppressed by applying the first binder coating liquid 4 to the center part in the width direction of the active material layer and applying the second binder coating liquid 8 to both ends in the width direction. Can do. Therefore, the shearing force applied to the powder 16 when passing through the squeegee member 20 while making the basis weight of the powder 16 at both ends in the width direction of the active material layer larger than the basis weight of the powder 16 at the center portion. A good electrode can be produced without reducing the electrode production efficiency.

  The width of the end portion in the width direction of the active material layer to which the second binder coating liquid 8 is applied is preferably 0.5% or more and 5% or less with respect to the width of the active material layer. This is because the shearing force applied to the powder 16 when passing through the squeegee member 20 is appropriately maintained, and the production efficiency of the electrode is not lowered.

  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, Microtrac MT3300EX II; Nikkiso).

  According to the method for manufacturing an electrode for a lithium ion battery according to this embodiment, the region 12a of the base material 12 corresponding to the center portion in the width direction of the electrode active material layer for the lithium ion battery using the powder molding apparatus 2. The first binder coating solution 4 is applied to the electrode 12, and the second binder coating solution 8 is applied to the regions 12 b and 12 c of the base material 12 corresponding to both ends in the width direction of the electrode active material layer for the lithium ion battery. . That is, in order to apply the second binder coating liquid 8 having a high tack strength and a high solid content concentration to the regions 12b and 12c of the base material 12 corresponding to both ends in the width direction of the electrode active material layer for the lithium ion battery, The basis weight of the powder 16 deposited on the regions 12a and 12b can be increased. Therefore, the peel strength between the active material layer 24 and the substrate 12 at both ends in the width direction of the active material layer can be maintained high, and the active material layer 24 at both ends in the width direction peels from the surface of the substrate 12. Can be prevented.

  In the above-described embodiment, the first binder coating liquid 4 is applied to the area 12a of the base 12 and the second binder coating liquid 8 is applied to the areas 12b and 12c of the base 12 (see FIG. 2). ) Although a single electrode is manufactured, for example, as shown in FIG. 5, the second binder coating liquid is applied to the regions 12d and 12e at both ends in the width direction and the region 12f at the center in the width direction as shown in FIG. 8 may be applied, and the first binder coating solution 4 may be applied to the regions 12g and 12h other than the regions 12d, 12e, and 12f to manufacture two electrodes. In this case, after finishing the powder forming in the powder forming apparatus 2, two electrodes are manufactured by cutting at the position of the broken line L shown in FIG.

  The tack strength of the binder used in the binder coating liquids (the first binder coating liquid and the second binder coating liquid) used in the following examples and comparative examples is a measurement result of the probe tack method. Is due to. Binder used for binder coating liquid (first binder coating liquid and second binder coating liquid) in an atmosphere at 25 ° C. using a tacking tester (TAC-1000: manufactured by Reska). The probe tack with respect to the SUS probe (10 mmφ) was measured, and the tack strength (N / 10 mmφ) of the binder was obtained.

Example 1
Using the powder molding apparatus 2 shown in FIG. 1, a first binder coating liquid having a tack strength of 1.5 N / 10 mmφ and a solid content concentration of 30% is formed on the base corresponding to the central portion in the width direction of the active material layer. On the surface of the material, a second binder coating liquid having a tack strength of 4.2 N / 10 mmφ and a solid content concentration of 30% is applied to both end portions in the width direction of the active material layer (the end portion in the width direction of the active material layer is the active material). 2% of the width of the layer) was applied to the substrate surface to obtain an electrode sheet. Table 1 shows the adhesive strength at both ends of the active material layer, the production efficiency of the electrode sheet, and the low-temperature reaction resistance (here, “low temperature” refers to a low temperature (for example, −30 ° C.) relative to normal temperature (25 ° C.)).

(Example 2)
Using the powder molding apparatus 2 shown in FIG. 1, a first binder coating liquid having a tack strength of 1.5 N / 10 mmφ and a solid content concentration of 30% is formed on the base corresponding to the central portion in the width direction of the active material layer. On the surface of the material, a second binder coating liquid having a tack strength of 2.3 N / 10 mmφ and a solid content concentration of 30% is applied to both end portions in the width direction of the active material layer (the end portion in the width direction of the active material layer is the active material). 2% of the width of the layer) was applied to the substrate surface to obtain an electrode sheet. Table 1 shows the adhesive strength at both ends of the active material layer, the production efficiency of the electrode sheet, and the low-temperature reaction resistance.

(Example 3)
Using the powder molding apparatus 2 shown in FIG. 1, a first binder coating liquid having a tack strength of 1.5 N / 10 mmφ and a solid content concentration of 30% is formed on the base corresponding to the central portion in the width direction of the active material layer. On the surface of the material, a second binder coating liquid having a tack strength of 1.5 N / 10 mmφ and a solid content concentration of 46% is applied to both ends in the width direction of the active material layer (the ends in the width direction of the active material layer are the active material). 2% of the width of the layer) was applied to the substrate surface to obtain an electrode sheet. Table 1 shows the adhesive strength at both ends of the active material layer, the production efficiency of the electrode sheet, and the low-temperature reaction resistance.

Example 4
Using the powder molding apparatus 2 shown in FIG. 1, a first binder coating liquid having a tack strength of 1.5 N / 10 mmφ and a solid content concentration of 30% is formed on the base corresponding to the central portion in the width direction of the active material layer. On the surface of the material, a second binder coating liquid having a tack strength of 1.5 N / 10 mmφ and a solid content concentration of 40% is applied to both ends in the width direction of the active material layer (the ends in the width direction of the active material layer are active materials). 2% of the width of the layer) was applied to the substrate surface to obtain an electrode sheet. Table 1 shows the adhesive strength at both ends of the active material layer, the production efficiency of the electrode sheet, and the low-temperature reaction resistance.

(Example 5)
Using the powder molding apparatus 2 shown in FIG. 1, a first binder coating liquid having a tack strength of 1.5 N / 10 mmφ and a solid content concentration of 30% is formed on the base corresponding to the central portion in the width direction of the active material layer. On the surface of the material, a second binder coating liquid having a tack strength of 3.5 N / 10 mmφ and a solid content concentration of 30% is applied to both ends in the width direction of the active material layer (the ends in the width direction of the active material layer are active materials). The electrode sheet was obtained by applying to the surface of the substrate corresponding to 8% of the layer width). Table 1 shows the adhesive strength at both ends of the active material layer, the production efficiency of the electrode sheet, and the low-temperature reaction resistance.

(Comparative Example 1)
Using the powder molding apparatus 2 shown in FIG. 1, a binder coating liquid having a tack strength of 1.5 N / 10 mmφ and a solid content concentration of 30% was applied to the surface of the substrate to obtain an electrode sheet. Table 1 shows the adhesive strength at both ends of the active material layer, the production efficiency of the electrode sheet, and the low-temperature reaction resistance.

(Comparative Example 2)
Using the powder molding apparatus 2 shown in FIG. 1, a binder coating liquid having a tack strength of 4.2 N / 10 mmφ and a solid content concentration of 30% was applied to the substrate surface to obtain an electrode sheet. Table 1 shows the adhesive strength at both ends of the active material layer, the production efficiency of the electrode sheet, and the low-temperature reaction resistance.

(Comparative Example 3)
Using the powder molding apparatus 2 shown in FIG. 1, a binder coating solution having a tack strength of 1.5 N / 10 mmφ and a solid content concentration of 45% was applied to the substrate surface to obtain an electrode sheet. Table 1 shows the adhesive strength at both ends of the active material layer, the production efficiency of the electrode sheet, and the low-temperature reaction resistance.

  T1 is the tack strength of the binder contained in the first binder coating liquid, T2 is the tack strength of the binder contained in the second binder coating liquid, and C1 is the solid content of the first binder. Concentration, C2, is the solid content concentration of the second binder. Further, as a result of the adhesive strength at the end portion, A indicates that the adhesive strength is high, B indicates that the adhesive strength is lower than A, and D indicates that the adhesive strength is lower than B. The result ○ of production efficiency indicates high production efficiency, and x indicates low production efficiency, the result A of low temperature reaction resistance indicates low resistance, and B indicates higher resistance than A.

  As described above, as shown in the results of Examples and Comparative Examples shown in Table 1, when the binder coating liquid having high tack strength or high solid content concentration is applied to both ends in the width direction of the electrode sheet, high production efficiency and While maintaining low resistance, an electrode sheet in which the peel strength between the active material layer and the substrate at the end is maintained high, that is, an electrode sheet in which the active material layer at the end is difficult to peel from the substrate can be obtained.

  DESCRIPTION OF SYMBOLS 2 ... Powder shaping | molding apparatus, 4 ... 1st binder coating liquid, 6 ... 1st application part, 6a ... 1st storage tank, 6b ... 1st gravure roll, 8 ... 2nd binder coating liquid, 10 ... 2nd coating part, 10a ... 2nd storage tank, 10b ... 2nd gravure roll, 12 ... base material, 14a, 14b ... transport roller, 16 ... powder, 18 ... hopper, 20 ... squeegee member, 22A, 22B ... press Roll, 24 ... active material layer.

Claims (4)

A first application step of applying a first binder coating liquid to a substrate surface corresponding to a center portion in the width direction of the electrode active material layer for a lithium ion battery;
A second application step of applying a second binder coating liquid different from the first binder coating liquid on the surface of the base material corresponding to both ends in the width direction of the electrode active material layer for the lithium ion battery;
Supplying a powder containing an electrode active material to the surface of the base material on which the first binder coating liquid and the second binder coating liquid are applied;
A control step of controlling the basis weight of the powder supplied to the substrate surface;
A forming step of forming an active material layer by pressing the powder supplied to the substrate surface using a pair of pressing rolls;
Including
The tack strength of the binder used in the second binder coating liquid is greater than the tack strength of the binder used in the first binder coating liquid, or the solid content of the second binder coating liquid. The method for producing an electrode for a lithium ion battery, wherein the concentration is higher than the solid content concentration of the first binder coating liquid.   The tack strength of the binder used for the second binder coating liquid is 1.5 times or more of the tack strength of the binder used for the first binder coating liquid. Item 2. A method for producing an electrode for a lithium ion battery according to Item 1.   3. The lithium ion according to claim 1, wherein the solid content concentration of the second binder coating liquid is 1.3 times or more the solid content concentration of the first binder coating liquid. Manufacturing method of battery electrode.   The width of the end portion in the width direction of the electrode active material layer for the lithium ion battery is 0.5% or more and 5% or less with respect to the width of the electrode active material layer for the lithium ion battery. The manufacturing method of the electrode for lithium ion batteries as described in any one of Claims 1-3.

Images