JP2007273313A - Electrode plate for nonaqueous electrolyte secondary battery, its manufacturing method, and nonaqueous electrolyte secondary battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrode plate for a nonaqueous electrolyte secondary battery having a void ratio enough to secure excellent permeability and electrolyte retention capability of an electrolyte, and having a low volume resistivity by ensuring excellent contact of conductive agent particles. <P>SOLUTION: This electrode plate for a nonaqueous electrolyte secondary battery having an electrode active material layer at least on one surface of a collector is composed. The electrode active material layer contains a void formation agent comprising at least an active material, a conductive agent, a binder and a coil-like substance. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electrode plate for a nonaqueous electrolyte secondary battery represented by a lithium ion secondary battery, a method for producing the same, and a nonaqueous electrolyte secondary battery using the same.

  Non-aqueous electrolyte secondary batteries represented by lithium ion secondary batteries have high energy density, high voltage, and no memory effect during charging / discharging, so they can be used in various fields such as portable devices and large devices. It is used. A general non-aqueous electrolyte secondary battery is composed of a positive electrode, a negative electrode, a separator, and an organic electrolyte, and the positive electrode and the negative electrode are necessary for an active material and a binder that can be charged and discharged on a current collector such as a metal foil. Depending on the type, a film formed by mixing a conductive agent is used. The coating film is usually formed by kneading and dispersing an active material, a binder, and other materials in a solvent to form a slurry-like coating liquid, which is applied to a current collector and dried ( For example, Patent Documents 1 and 2).

In recent years, development has been progressing especially for fields that require high output characteristics such as electric vehicles, hybrid vehicles, and power tools. A battery with high impedance cannot make full use of its capacity during high output charge / discharge. Therefore, for example, a method of reducing the impedance of the battery by increasing the film area of the coating film is used. For example, lithium ion secondary batteries use non-aqueous electrolytes that generally have higher resistance than aqueous electrolytes, and have used electrodes that are thinner and wider than other batteries such as lead-acid batteries from the beginning of development. In addition, the distance between the electrode plates is shortened.
JP 63-10456 A JP-A-3-285262

  The current collector on which the coating film is formed is pressed as necessary, and then cut or punched into a predetermined shape to form an electrode. The press after the formation of the coating film is generally effective in increasing the density of the coating film and improving the volume energy density of the battery, and at the same time improving the adhesion with the current collector. Moreover, when the electrically conductive agent is added to the coating film, there exists an effect which improves the contact of electrically conductive agent particle | grains and ensures the favorable electronic conduction path (conductive path) from an electrical power collector to an active material particle. As the conductive path is secured, the volume resistivity of the coating film decreases.

  As a general method for reducing the volume resistivity, for example, the amount of conductive agent such as acetylene black is increased and pressed, and the density of the coating film is increased to increase the contact point or the contact area between the conductive agent particles. There is a way. However, this method has a problem in that the porosity of the coating film decreases and the electrolyte permeability and liquid retention deteriorate, resulting in a decrease in discharge capacity and an increase in internal resistance at high output. .

  Therefore, a non-aqueous electrolyte secondary battery having a sufficient porosity to ensure good permeability and liquid retention of the electrolyte and low volume resistivity by ensuring good contact of the conductive agent particles An object of the present invention is to provide an electrode plate.

  In order to solve the above-mentioned problems, the present inventors have intensively studied and, as a result, by using a void forming agent made of a coiled substance, while ensuring a porosity that gives good permeability and liquid retention of the electrolyte, The present invention has been completed by finding that it is possible to provide an electrode plate for a non-aqueous electrolyte secondary battery that provides a low volume resistivity. That is, the electrode plate for a non-aqueous electrolyte secondary battery of the present invention is an electrode plate for a non-aqueous electrolyte secondary battery comprising an electrode active material layer on at least one surface of a current collector, and the electrode active material layer Is characterized in that it contains at least a void forming agent comprising an active material, a conductive agent, a binder, and a coiled material.

  The electrode plate of the present invention includes at least one selected from the group consisting of coiled carbon fiber, coiled metal fiber, coiled conductive metal oxide fiber, and a mixture of two or more thereof as the coiled material. Can be used.

  In addition, a coiled material having an outer diameter of 50 to 1000 nm and a length of 0.1 to 10 μm can be used for the electrode plate of the present invention.

Moreover, the electrode plate of this invention can be used for a positive electrode plate. Here, the volume resistivity of the electrode active material layer of the positive electrode plate is preferably 4 Ω · cm or less. Moreover, it is preferable that the density after the press of an electrode active material layer is 2.0-3.5 g / cm < ³ >.

A non-aqueous electrolyte secondary battery using the electrode plate of the present invention is a non-aqueous electrolyte secondary battery including at least a positive electrode plate, a negative electrode plate, and an electrolyte, and at least one of the positive electrode plate and the negative electrode plate is And an electrode plate in which an electrode active material layer containing at least an active material, a conductive agent, a binder, and a void forming agent made of a coiled material is formed on at least one surface of the current collector. It is a feature. The electrode plate is preferably used as a positive electrode plate. In that case, the volume resistivity of the electrode active material layer of the positive electrode plate is preferably 4 Ω · cm or less, and the density of the electrode active material layer after pressing is 2.0 to 3.5 g / cm ³ . It is preferable.

  The electrode plate of the present invention includes a void forming agent made of a coiled material in the electrode active material layer. The coiled substance is a substance in which a fibrous substance is curved in a coil shape and has a hollow region inside. In the present invention, the hollow region functions as a gap for ensuring the permeability and liquid retention of the electrolytic solution. Since the coiled material is difficult to be deformed due to its rigidity, the hollow region has a property that the hollow region is difficult to decrease even during pressing. Therefore, even if the amount of the conductive agent such as acetylene black is increased, the volume resistivity of the electrode active material layer can be reduced without reducing the porosity.

An electrode plate for a non-aqueous electrolyte secondary battery according to the present invention is an electrode plate for a non-aqueous electrolyte secondary battery including an electrode active material layer on at least one surface of a current collector, the electrode active material layer being At least a void forming agent composed of an active material, a conductive agent, a binder, and a coiled material is included.
Here, the positive electrode includes a positive electrode active material as an active material, and the negative electrode includes a negative electrode active material as an active material.

(Active material)
As a positive electrode active material, the material conventionally used as a positive electrode active material of a nonaqueous electrolyte secondary battery can be used. For example, lithium transition metal composite oxides such as LiMn ₂ O ₄ (lithium manganate), LiCoO ₂ (lithium cobaltate) or LiNiO ₂ (lithium nickelate), or TiS ₂ , MnO ₂ , MoO ₃ or V ₂ O Examples thereof include chalcogen compounds such as ₅ . In particular, by using LiCoO ₂ as a positive electrode active material and a carbonaceous material as a negative electrode active material, a lithium secondary battery having a high discharge voltage of about 4 volts can be obtained.

  The positive electrode active material is preferably a powder having an average particle size of 0.1 to 100 μm in order to uniformly disperse it in the coating film. These positive electrode active materials may be used alone or in combination of two or more.

  On the other hand, as a negative electrode active material, the material conventionally used as a negative electrode active material of a nonaqueous electrolyte secondary battery can be used. For example, carbonaceous materials such as natural graphite, artificial graphite, amorphous carbon, carbon black, or a carbon composite obtained by adding a different element to these components are preferably used. In addition, materials capable of occluding and releasing lithium ions such as metallic lithium and its alloys, tin, silicon, and alloys thereof can be generally used.

  The particle shape of the negative electrode active material is not particularly limited. For example, scaly, massive, fibrous, or spherical ones can be used. The negative electrode active material is preferably a powder having an average particle size of 0.1 to 100 μm in order to uniformly disperse it in the coating layer. These negative electrode active materials may be used alone or in combination of two or more.

  The content of the positive electrode or negative electrode active material in the electrode active material layer is 70 to 98% by weight, more preferably 80 to 98% by weight, based on the blended components excluding the solvent (based on solid content).

(Binder)
Conventionally used binders such as thermoplastic resins, more specifically polyester resins, polyamide resins, polyacrylate resins, polycarbonate resins, polyurethane resins, cellulose resins, polyolefin resins, polyvinyl resins. Fluorine resin or polyimide resin can be used. At this time, an acrylate monomer or oligomer into which a reactive functional group is introduced can be mixed in the binder. In addition, rubber-based resins, thermosetting resins such as acrylic resins and urethane resins, ionizing radiation curable resins composed of acrylate monomers, acrylate oligomers or mixtures thereof, and mixtures of the above various resins may be used. it can. A preferred binder is a fluorine-based resin, and includes a homopolymer of tetrafluoroethylene or vinylidene fluoride or a copolymer thereof. More preferred is polyvinylidene fluoride. The content rate of the electrically conductive agent in an electrode active material layer is 1.5-20 weight% on a solid content basis, More preferably, it is 4-15 weight%.

In addition, two or more types of fluororesins having different melting points can be used for the binder. By using a low melting point fluorine-based resin, for example, a fluorine-based copolymer elastomer, the residual stress inside the coating film can be further reduced by softening the elastomer at a low temperature.
For example, when polyvinylidene fluoride is used for the fluorine-based resin, a vinylidene fluoride-hexafluoropropylene copolymer or a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene copolymer may be used as the fluorine-based copolymer elastomer. preferable. In this case, the blending ratio of the polyvinylidene fluoride and the elastomer is 4.5: 5.5 to 9.5: 0.5, more preferably 5: 5 to 9: 1 by weight.

  Further, an ion conductive polymer can be used instead of a part of the binder. The ion conductive polymer includes a polymer solid electrolyte such as polyalkylene oxide and a partially crosslinked product thereof, and a polymer gel electrolyte such as polyacrylonitrile and / or a copolymer thereof, polymethyl methacrylate and / or a copolymer thereof. included. A polymer gel electrolyte is preferable, and polyacrylonitrile and / or a copolymer thereof is more preferable. This is because the electrolyte retention capacity is large. By using these ionic conductive polymers in combination with a binder, it is possible to improve the ionic conductivity of the electrode active material layer while ensuring the film formability of the electrode active material layer. The blending ratio of the ion conductive polymer and the binder is 0.1: 9.9 to 5: 5, more preferably 0.1: 9.9 to 4: 6, by weight.

(Conductive agent)
As the conductive agent, carbonaceous materials such as natural and artificial graphite, carbon black, and carbon fiber can be used. Here, carbon black includes acetylene black, furnace black, thermal black, and the like. More preferred is acetylene black. Furthermore, graphite and carbon fiber can also be added as needed. Here, it is preferable to use vapor grown carbon fiber as the carbon fiber.

  The particle shape, size, etc. of the conductive agent are not particularly limited. However, since the battery reaction occurs due to the ions contained in the electrolytic solution and the active material contained in the active material layer, voids (conductivity that allows the electrolytic solution to penetrate into the active material layer) For example, particles, fibers, porous sheets, and the like can be used as long as the space in which no agent or the like is present can be secured in the liquid retaining layer. When the conductive agent is particulate, the average particle size is 0.01 to 20 μm, preferably 0.03 to 5 μm. The content rate of the electrically conductive agent in an electrode active material layer is 1.5-30 weight% on a solid content basis, More preferably, it is 3-20 weight%.

(Void forming agent)
In the present invention, the coiled material used as the void forming agent is not particularly limited as long as it is a fibrous material curved in a coil shape. If a specific example is given, as what has electroconductivity, a coil-shaped carbon fiber, a coil-shaped metal fiber, a coil-shaped conductive metal oxide fiber, and a mixture of these 2 or more types can be mentioned. Moreover, as what has electrical insulation, a coil-like insulating metal oxide, and the above-mentioned coil-like carbon fiber, coil-like metal fiber, and coil-like conductive metal oxide fiber coated with an organic substance, and these The mixture of 2 or more types can be mentioned. Preferably, it is a coiled carbon fiber, a coiled metal fiber, a coiled conductive metal oxide fiber, and a mixture of two or more thereof having conductivity. Since it also serves as a conductive aid, the amount of the conductive agent can be reduced compared to the case where an insulating coil-like substance is used, and the voids can be further increased while ensuring a low volume resistivity.

  As the coiled carbon fiber, for example, a coiled carbon fiber manufactured by a vapor deposition method described in JP-A-10-37024 can be used. In this method, a raw material gas such as acetylene is pyrolyzed in the presence of a catalyst to produce a coiled hydrocarbon. Moreover, what consists of Ni, Al, and Ti can be used for a coil-shaped metal fiber. For example, it can be produced by plating Ni or the like on the surface of the coiled carbon fiber. It can also be produced by immersing coiled carbon fibers in molten aluminum and providing an aluminum layer on the surface. Moreover, what consists of oxides, such as a silicon dioxide, a titanium dioxide, an aluminum oxide, a zirconium oxide, nickel oxide, can be used for a coil-shaped metal oxide fiber. For example, it can be produced by bringing a metal alkoxide into contact with the surface of a coiled carbon fiber in a liquid phase or a gas phase and performing a heat treatment to form a metal oxide layer on the surface of the coiled carbon fiber. It can also be produced by oxidizing the surface of the coiled metal fiber. Moreover, a silane coupling agent, a fluorine-type coupling agent, and insulating resin can be used for the organic substance which coat | covers a coil-shaped carbon fiber, a coil-shaped metal fiber, and a coil-shaped electroconductive metal oxide fiber. As the insulating resin, known resins such as (meth) acrylic resins, polystyrene resins, polyester resins, polyurethane resins, polyamide resins, and epoxy resins can be used.

  The outer diameter of the coiled substance is 50 to 1000 nm and the length is 0.1 to 10 μm, more preferably the outer diameter is 100 to 500 nm and the length is 0.5 to 5 μm. If the outer diameter is smaller than 50 nm, the effect of forming voids is not sufficient. If larger than 1000 nm, the hollow region of the coiled material is filled with an active material, a conductive agent, a binder, etc., and a sufficient void ratio is ensured. This is because it becomes difficult to increase the density of the electrode active material layer. The same applies to the length. If the thickness is smaller than 0.1 μm, the effect of forming a void is not sufficient, and if it is larger than 10 μm, it is difficult to increase the density of the electrode active material layer. The content of the coiled material in the electrode active material layer is 15% by weight or less, preferably 1 to 10% by weight.

  The thickness of the electrode active material layer is preferably 10 to 100 μm in order to reduce the resistance. The porosity of the electrode active material layer is 15 to 40%, more preferably 20 to 40%.

  For the current collector of the electrode plate, an aluminum foil can be used for the positive electrode plate, and a copper foil such as an electrolytic copper foil or a rolled copper foil can be used for the negative electrode plate. The thickness of the current collector is preferably 5 to 50 μm.

(Production method of electrode plate)
The electrode plate can be produced by applying a coating liquid containing an active material, a conductive agent, a binder and the like on a current collector by a coating method to form a coating film. That is, the electrode plate manufacturing method of the present invention forms an electrode active material layer by applying a coating liquid containing at least an active material, a conductive agent, a binder, a void forming agent, and a solvent on a current collector. At least a step of drying the electrode active material layer to remove the solvent to obtain an electrode plate, and a step of hot pressing the electrode plate and rolling.

  As a solvent for preparing a coating liquid for forming a positive electrode coating film and a negative electrode coating film, a binder such as toluene, methyl ethyl ketone, N-methyl-2-pyrrolidone or a mixture thereof, or ion-exchanged water is used. Solvents that can be dissolved and dispersed can be used. The ratio of the solvent in the coating liquid is 30 to 60% by weight, preferably 45 to 55% by weight, and the coating liquid is prepared in a slurry form. Add appropriately selected positive or negative electrode active material, binder, conductive agent and void forming agent to an appropriate solvent, and mix and disperse with a disperser such as a homogenizer, ball mill, sand mill, roll mill or planetary mixer. Can be prepared. If necessary, a conductive additive, a thickener, a dispersant, etc. can be added.

The application method is not particularly limited, and for example, die coating, comma coating, or the like can be used. When the viscosity of the coating liquid is low, it can be applied by gravure coating, spray coating, dip coating, or the like. The application shape may form a pattern such as intermittent coating as necessary. The liquid retaining layer and the active material layer may be formed by repeating coating and drying a plurality of times, or after coating three or more layers, the three or more layers may be dried at once. Incidentally, the coating amount or the amount of the formed electrode film, 10 to 300 g / ^{m 2} (one side) is preferably 20 to 200 g / ^{m 2} (one side).

  After coating, the electrode active material layer is dried to remove the solvent in the coating film. The method for removing the solvent is not particularly limited, but may be appropriately selected from general techniques such as hot air drying, far-infrared drying, contact drying, reduced pressure drying, freeze drying drying, or a combination of these. it can.

  The electrode plate thus formed is further rolled by room temperature pressing or hot pressing. It is preferable to perform hot pressing. By performing heating and pressing at the same time, the binder can be softened and recrystallized in a state of being fused to the conductive agent particles, and internal stress generated in the binder during pressing can be suppressed. Thereby, not only can the springback be suppressed even when immersed in the electrolytic solution, but also the density of the electrode active material layer, the adhesion of the electrode active material layer to the current collector, and the homogeneity can be improved. The pressing is performed using, for example, a metal roll, an elastic roll, a heating roll, or a sheet press machine. The pressing temperature is preferably 60% or more of the melting point of the binder and lower than the thermal decomposition temperature of the binder. More preferably, the temperature is 60 to 150%, more preferably 70 to 120% of the melting point of the binder. For example, when polyvinylidene fluoride is used as the binder, the melting point of polyvinylidene fluoride is about 170 ° C. and the thermal decomposition temperature is about 360 ° C. Therefore, the preferred temperature of the hot press is 100 to 360 ° C., more preferably 100 It is -250 degreeC, More preferably, it is 120-200 degreeC.

  Moreover, the roll press can continuously press a long sheet-like electrode plate. When performing a roll press, either a stereotaxic press or a constant pressure press may be performed. The line speed of the press is 5 to 50 m / min. When the pressure of the roll press is managed by linear pressure, the pressure is adjusted according to the diameter of the pressure roll, but the linear pressure can be 4.9 N / cm to 9800 N / cm.

Moreover, when performing a sheet press, a pressure is adjusted to the range of 4903-73550 N / cm < ² >, Preferably 29420-49033 N / cm < ² >. If the pressing pressure is too low, it is difficult to obtain a homogeneity of the chargeable / dischargeable laminated structure. If the pressing pressure is too high, the electrode plate itself including the current collector may be damaged. The chargeable / dischargeable laminated structure may have a predetermined thickness by a single press, or may be pressed several times for the purpose of improving homogeneity.

  The electrode plate produced as described above has a sufficient porosity to ensure good permeability and liquid retention of the electrolyte, and low volume resistivity by ensuring good contact of the conductive agent particles. Have In addition, when hot pressing is performed, the springback is suppressed even when immersed in an electrolyte solution, so that the density change after immersion is also suppressed and the increase in volume resistivity of the electrode active material layer is suppressed. Have. Specifically, in the electrode plate of the present invention, the volume resistance value before immersion in a carbonate solvent is R1, and the volume resistance value after immersion for 1 minute at room temperature and drying is R2, and the equation ΔR = [(R2− R1) / R1] × 100, the volume resistivity increasing rate ΔR is 5% or less, more preferably 2% or less. Solvents that do not contain an electrolyte generally have a greater ability to dissolve solutes and a greater swelling effect on the coating film than electrolytes that contain electrolytes. However, the electrode plate of the present invention can suppress swelling of the coating film even when a solvent is used, and as a result, springback can be significantly suppressed.

  As the carbonate ester solvent, one selected from the group consisting of ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate, more preferably diethyl carbonate can be used.

Further, the volume resistance value at room temperature (25 ° C.) of the electrode active material layer of the produced electrode plate is 4 Ω · cm or less, more preferably 2 Ω · cm or less. Further, the density after pressing of the electrode active material layer, 2.0~3.5g / cm ^3, more preferably 2.2~2.8g / cm ^3.

(Production of battery)
Using the produced electrode plate, a non-aqueous electrolyte secondary battery can be produced by the following method. In addition, although the electrode plate for nonaqueous electrolyte secondary batteries in this invention can be used for at least one of a positive electrode plate and a negative electrode plate, using for a positive electrode plate is preferable. In the case of the positive electrode plate, since the conductivity of the positive electrode active material is lower than that of the negative electrode active material, it is usually necessary to add a large amount of a conductive agent, and therefore the porosity is lowered. However, by using the electrode plate of the present invention, it is possible to ensure a low volume resistivity without reducing the porosity.

  The positive electrode plate and the negative electrode plate are spirally wound through a separator such as a polyethylene porous film and inserted into an outer container. Alternatively, the positive electrode plate and the negative electrode plate cut out in a predetermined shape are stacked and fixed via a separator, and inserted into an outer container. After the insertion, the lead wire attached to the positive electrode plate is connected to the positive electrode terminal provided in the outer container, while the lead wire attached to the negative electrode plate is connected to the negative electrode terminal provided in the outer container, By filling and sealing the electrolyte, a non-aqueous electrolyte secondary battery equipped with the electrode plate according to the present invention is completed.

When producing a lithium secondary battery, a nonaqueous electrolytic solution in which a lithium salt as a solute is dissolved in an organic solvent is used. Examples of the lithium salt include inorganic lithium salts such as LiClO ₄ , LiBF ₄ , LiPF ₆ , LiAsF ₆ , LiCl, LiBr, or LiB (C ₆ H ₅ ) ₄ , LiN (SO ₂ CF ₃ ) ₂ , LiC (SO _{2 CF 3) 3, LiOSO 2} CF 3, LiOSO 2 C 2 F 5, LiOSO 2 C 3 F 7, LiOSO 2 C 4 F 9, LiOSO 2 C 5 F 11, LiOSO 2 C 6 F 13, LiOSO 2 C 7 organic lithium salt F ₁₅ or the like can be used alone or more.

  As an organic solvent for dissolving the lithium salt, a carbonate ester solvent including a cyclic ester group or a chain ester group, a cyclic ether solvent, a chain ether solvent, or the like can be used.

  Examples of the cyclic ester solvent include propylene carbonate, butylene carbonate, γ-butyrolactone, vinylene carbonate, 2-methyl-γ-butyrolactone, acetyl-γ-butyrolactone, and γ-valerolactone.

  As chain ester solvents, dimethyl carbonate, diethyl carbonate, dibutyl carbonate, dipropyl carbonate, methyl ethyl carbonate, methyl butyl carbonate, methyl propyl carbonate, ethyl butyl carbonate, ethyl propyl carbonate, butyl propyl carbonate, propionic acid alkyl ester, Examples include malonic acid dialkyl esters and acetic acid alkyl esters.

  Examples of the cyclic ether solvent include tetrahydrofuran, alkyltetrahydrofuran, dialkyltetrahydrofuran, alkoxytetrahydrofuran, dialkoxytetrahydrofuran, 1,3-dioxolane, alkyl-1,3-dioxolane, 1,4-dioxolane and the like.

  Examples of chain ether solvents include 1,2-dimethoxyethane, 1,2-diethoxyethane, diethyl ether, ethylene glycol dialkyl ether, diethylene glycol dialkyl ether, triethylene glycol dialkyl ether, and tetraethylene glycol dialkyl ether. be able to.

Example 1
100 parts by weight of LiCoO ₂ powder having an average primary particle size of 1 μm as the positive electrode active material, 12.5 parts by weight of acetylene black as the conductive agent, 2.5 parts by weight of coiled carbon having an outer diameter of 250 nm and a length of 5 μm, As a coating agent, 10 parts by weight of polyvinylidene fluoride (PVDF) was added so that N-methylpyrrolidone (NMP) as a solvent had a solid content of 50%, and the mixture was dispersed to prepare an electrode coating solution.

<Volume resistivity evaluation method>
The electrode coating solution prepared on the PET film is applied and dried to obtain a sheet having a coating amount of about 120 g / m ² , pressed to a density of about 2.3 g / cm ³ , and then using a low resistivity meter. The volume resistivity was measured by a four-terminal four-probe method according to JIS K7194.

<Porosity evaluation method>
The thickness 15μm on the aluminum foil, the prepared electrode coating solution is applied and dried to give a coating weight of the electrode plates of about 120 g / m ^2. The electrode plate was pressed to a density of about 2.3 g / cm ³ , cut into 5 cm × 5 cm, and the porosity of pores in the range of 30 nm to 1 μm was measured using a mercury intrusion porosimeter.

(Comparative Example 1)
An electrode coating solution was prepared in the same manner as in Example 1 except that 15 parts by weight of acetylene black was used as a conductive agent without adding coiled carbon, and a sheet prepared from the coating solution was further prepared. Volume resistivity and porosity were measured.

(result)
The results are shown in Table 1. In Example 1, the volume resistivity decreased compared to Comparative Example 1, and a large porosity was obtained even after pressing to a density of about 2.3 g / cm ³ .

Claims (8)

  An electrode plate for a non-aqueous electrolyte secondary battery comprising an electrode active material layer on at least one surface of a current collector, the electrode active material layer comprising at least an active material, a conductive agent, a binder, and a coiled material An electrode plate for a non-aqueous electrolyte secondary battery comprising a void forming agent comprising:   2. The non-coating material according to claim 1, wherein the coiled material is at least one selected from the group consisting of a coiled carbon fiber, a coiled metal fiber, a coiled conductive metal oxide fiber, and a mixture of two or more thereof. Electrode plate for water electrolyte secondary battery.   The electrode plate for a nonaqueous electrolyte secondary battery according to claim 1 or 2, wherein the outer diameter of the coiled substance is 50 to 1000 nm and the length is 0.1 to 10 µm.   The electrode plate for a nonaqueous electrolyte secondary battery according to any one of claims 1 to 3, wherein the electrode plate is a positive electrode plate.   The electrode plate for a nonaqueous electrolyte secondary battery according to claim 4, wherein the electrode active material layer has a volume resistivity of 4 Ω · cm or less. The electrode plate for a non-aqueous electrolyte secondary battery according to claim 4 or 5, wherein the density of the electrode active material layer after pressing is 2.0 to 3.5 g / cm ³ .   A non-aqueous electrolyte secondary battery comprising at least a positive electrode plate, a negative electrode plate, and an electrolyte, wherein at least one of the positive electrode plate and the negative electrode plate is at least on one surface of a current collector, at least an active material, a conductive agent, A non-aqueous electrolyte secondary battery, which is an electrode plate formed with an electrode active material layer containing a binder and a void-forming agent comprising a coiled substance. The nonaqueous electrolyte secondary battery according to claim 7, wherein the electrode plate is used as a positive electrode plate.