JP2012094343A - Nonaqueous electrolyte secondary battery electrode plate manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a nonaqueous electrolyte secondary battery electrode plate which has high adhesion between a current collector and an electrode active material layer and high long-term storage ability and excels in output-input characteristics.SOLUTION: The manufacturing method comprises a surface treatment process of treating the surface of a current collector consisting of aluminum in such a way that, in an element abundance ratio obtained from the peak of carbon: 1s and aluminum: 2p by an X-ray electron spectroscopy, the number of carbon elements/number of aluminum elements is 148% or less; a process which, after the surface treatment process, forms on the current collector a precursor which includes at least electrode active material particles and a metal element-containing compound; and a process of heating to a temperature or higher than that at which the metal element-containing compound included in the precursor becomes a metal oxide.

Description

  The present invention relates to a method for producing an electrode plate for a non-aqueous electrolyte secondary battery.

  Non-aqueous electrolyte secondary batteries have a high energy density and high voltage, and the phenomenon that the battery capacity gradually decreases when the battery is charged before it is completely discharged at the time of charging / discharging, so-called memory effect. Since it does not exist, it is used in various fields such as portable devices, notebook computers, and portable devices.

Currently, as a measure to prevent global warming, efforts to reduce CO ₂ emissions are being carried out on a global scale. By reducing the dependence on oil and allowing it to travel with a low environmental load, it can greatly reduce CO ₂ emissions. There is an urgent need to develop and promote next-generation clean energy vehicles represented by plug-in hybrid vehicles and electric vehicles that can contribute. If non-aqueous electrolyte secondary batteries can be used as the driving force for these next-generation clean energy vehicles, there is no need to rely on gasoline, which can greatly contribute to CO ₂ reduction and greatly prevent global warming. Can contribute. On the other hand, in order for non-aqueous electrolyte secondary batteries to be used as the driving force for next-generation clean energy vehicles, the performance of each part that constitutes the battery, such as an electrode plate, is improved and these parts are improved. It is necessary to produce with high accuracy and high yield.

  Currently, various proposals of non-aqueous electrolyte secondary batteries include a positive electrode plate, a negative electrode plate, a separator, and a non-aqueous electrolyte solution. The positive electrode plate is generally provided with an electrode active material layer in which positive electrode active material particles are fixed on the current collector surface. Moreover, as a negative electrode plate, what is equipped with the electrode active material layer by which a negative electrode active material particle adheres to the collector surface is common. Aluminum foil is widely used as a current collector. This aluminum foil is generally formed by rolling an aluminum block, and the surface of the formed aluminum foil is usually used to improve the slipperiness in the rolling process. The organic component remains.

  In order to manufacture the electrode plate which is the positive electrode plate or the negative electrode plate, first, the electrode active material particles which are the positive electrode active material particles or the negative electrode active material particles, the resin binder, or further, the conductive material or other materials as necessary. The material is kneaded and / or dispersed in a solvent to prepare a slurry-like electrode active material layer forming liquid. And an electrode plate provided with an electrode active material layer is formed by applying an electrode active material layer forming liquid on the current collector surface, then drying to form a coating film on the current collector, and pressing (for example, Patent Document 1 or Patent Document 2).

  At this time, the electrode active material particles contained in the electrode active material layer forming liquid are particulate metal compounds dispersed in the liquid, and as such, are applied to the surface of the current collector, dried, and pressed. Even if it is done, it will be hard to adhere to the surface of the current collector, and will peel off from the current collector immediately. Therefore, when forming the electrode active material layer, a resin binder is added to the electrode active material layer forming liquid, and the electrode active material particles are fixed on the current collector by the resin binder, and the electrode active material The particles are fixed to each other.

JP 2006-310010 A JP 2006-107750 A

  However, since the electrode plate formed by the method proposed in Patent Document 1 and Patent Document 2 described above, the electrode active material particles, the current collector, and the electrode active material particles are fixed with a resin binder, There is a problem that the impedance of the electrode active material layer becomes large and the output characteristics cannot be improved.

  In order to solve such problems, there is an attempt to replace all or part of the resin binder with a metal oxide, that is, to fix the electrode active material particles, the current collector and the electrode active material particles to each other with the metal oxide. Has been made. By using a metal oxide instead of the resin binder, the impedance of the electrode active material layer can be reduced by the amount of using the metal oxide, thereby improving the output characteristics.

  As a method for producing an electrode plate fixed with a metal oxide, for example, (1) a step of forming a current collector made of aluminum foil by applying a precursor containing at least electrode active material particles and a metal element-containing compound. And (2) a step of heating at or above a temperature at which the metal element-containing compound in the precursor becomes a metal oxide. According to the method, in the process of changing the metal element-containing compound contained in the precursor into a metal oxide by pyrolysis or the like, the electrode active material particles contained in the precursor, and the precursor It is convenient because the current collector and the electrode active material particles below can be fixed by metal oxides.

  However, when an aluminum foil is used as the current collector, organic components remain on the surface as described above. Therefore, when this electrode plate is used for a non-aqueous electrolyte secondary battery, the current collector The organic component remaining on the body reacts with the non-aqueous electrolyte, and the long-term storage characteristics are deteriorated. In addition, when the electrode plate is formed by the above method, it is necessary to heat at a temperature higher than the temperature at which the metal element-containing compound becomes a metal oxide, which is stronger than the case where only the conventional resin binder is used. Adhesion is required. However, when the organic component remains on the current collector, the adhesion between the current collector and the precursor deteriorates, and the adhesion between the current collector and the electrode active material layer in the obtained electrode plate The properties will also be reduced.

  The present invention has been made in view of such a situation, and has high adhesiveness between a current collector and an electrode active material layer, high long-term storage, and excellent input / output characteristics, and for a non-aqueous electrolyte secondary battery. The main object is to provide a method for manufacturing an electrode plate.

  The manufacturing method of the present invention for solving the above problems is such that the number of carbon elements / the number of aluminum elements is 148% or less in the element abundance ratio obtained from the peaks of carbon: 1s and aluminum: 2p by X-ray electron spectroscopy. A surface treatment step of performing a surface treatment of a current collector made of aluminum, and a step of forming a precursor containing at least electrode active material particles and a metal element-containing compound on the current collector after the surface treatment step; And a step of heating at or above a temperature at which the metal element-containing compound in the precursor becomes a metal oxide.

  The surface treatment step may be a treatment for degreasing the current collector made of aluminum.

  According to the method for producing an electrode plate for a non-aqueous electrolyte secondary battery of the present invention, firstly, a precursor containing a metal element-containing compound is used, and this is heated to form a metal oxide. Therefore, the electrode active material particles and each of the electrode active material particles and the current collector can be fixed by the metal oxide derived from the metal element-containing compound. Therefore, it is possible to provide an electrode plate having a low impedance and excellent output characteristics as compared with a conventional electrode plate in which these are fixed using only a resin binder.

  Secondly, according to the method for producing an electrode plate for a non-aqueous electrolyte secondary battery of the present invention, aluminum as a current collector is an element obtained from the peaks of carbon: 1s and aluminum: 2p by X-ray electron spectroscopy. Since the surface treatment is performed so that the number of carbon elements / the number of aluminum elements is 148% or less in the abundance ratio, an electrode plate having high long-term storage and high adhesion between the current collector and the electrode active material layer is provided. can do.

(Method for producing electrode plate for non-aqueous electrolyte secondary battery)
Hereinafter, the manufacturing method of the electrode plate for nonaqueous electrolyte secondary batteries of this invention is demonstrated in detail.

  In the method of the present invention, (1) the number of carbon elements / the number of aluminum elements is 148% or less in the element abundance ratio obtained from the peak of carbon: 1s and aluminum: 2p by X-ray electron spectroscopy. And (2) at least the electrode active material particles and the metal element-containing compound on the current collector after the surface treatment step. A step of forming a precursor containing the precursor (hereinafter sometimes referred to as a “precursor formation step”), and (3) a step of heating at a temperature equal to or higher than a temperature at which the metal element-containing compound in the precursor becomes a metal oxide ( Hereinafter, it may be referred to as a “heating step”). Hereinafter, these steps will be described in detail.

(1) Surface treatment step In the method of the present invention, the surface treatment step refers to an element existing ratio obtained from a peak of carbon: 1 s and aluminum: 2 p by X-ray electron spectroscopy in a current collector made of aluminum, and a carbon element. This refers to the step of surface treatment so that the number / number of aluminum elements is 148% or less.

  In the method of the present invention, the current collector made of aluminum means that at least a part of the surface of the current collector is aluminum. As the current collector made of aluminum, for example, an aluminum foil or a base material such as a metal or resin other than aluminum coated with aluminum by a vapor deposition method or a plating method can be used. In the present invention, the organic component remaining on the aluminum foil widely used as a current collector deteriorates the adhesion between the current collector and the precursor, and the long-term non-aqueous electrolyte secondary battery. Although it was made in view of initially deteriorating the storage characteristics, it is obvious that the surface of the current collector is not limited to aluminum foil as long as the surface of the current collector is aluminum. In addition, in the method of this invention, the electrical power collector which consists of aluminum does not inhibit that metal components other than an impurity and a small amount of aluminum are contained in aluminum.

  In the surface treatment process in the present invention, the number of carbon elements / number of aluminum elements can be 148% or less in the element abundance ratio obtained from the peaks of carbon: 1s and aluminum: 2p by X-ray electron spectroscopy. A method can be appropriately selected and used. For example, conventionally known methods for removing carbon include ultraviolet irradiation treatment, plasma treatment, reduction treatment, corona discharge treatment, ultrasonic cleaning treatment, and the like.

  In the method of the present invention, the current collector after the surface treatment step has a carbon element number / aluminum element number of 148% or less in an element abundance ratio obtained from peaks of carbon: 1s and aluminum: 2p by X-ray electron spectroscopy. Therefore, it is possible to improve the adhesion with the precursor in the precursor forming step described later.

Whether or not the number of carbon elements / number of aluminum elements is 148% or less in the element abundance ratio obtained from the peak of carbon: 1s and aluminum: 2p by X-ray electron spectroscopy after the surface treatment step is determined by the surface treatment. The current collector made of aluminum can be confirmed by an X-ray electron spectrometer (ESCA-3400 manufactured by KARATOS). Specifically, the measurement is performed according to the following procedure. A current collector made of aluminum is cut into a 3 mm square to prepare a sample, and the sample is attached to a measurement holder washed with alcohol with a conductive double-sided tape. Next, the measurement holder to which the sample is attached is placed in a measurement chamber with a vacuum degree of 5.0 × 10 ⁻⁶ Pa or less, and in the range of 0 to 1100 eV in increments of 1 eV under conditions of an acceleration voltage of 10 kV and a current of 290 mA. X-ray is irradiated and measured at take-off angle of 90 degrees. The background is subtracted from the obtained spectrum, and elemental analysis is performed from the peak area derived from each element.

  The thickness of the current collector is not particularly limited, but when the positive electrode plate is a current collector used for production, the thickness is preferably about 3 to 150 μm, and the current collector used for production of the negative electrode plate Is preferably about 3 to 100 μm.

(2) Precursor formation step In the method of the present invention, the precursor formation step is the number of carbon elements in the element abundance ratio obtained from the peak of carbon: 1s and aluminum: 2p by X-ray electron spectroscopy in the surface treatment step. / On the current collector that has been surface-treated so that the number of aluminum elements is 148% or less, the electrode active material layer includes at least electrode active material particles and a metal element-containing compound, and is subjected to a heating process performed after this process. A process for forming a precursor to be formed.

  In the precursor formation step in the present invention, it is only necessary that a desired precursor can be formed on the current collector, and the formation method is not particularly limited, and various methods are appropriately selected. Can be used. For example, a printing method, spin coating, dip coating, bar coating, spray coating and the like can be mentioned. In addition, when the surface of the current collector is porous, has a large number of irregularities, or has a three-dimensional structure, it can be manually applied in addition to the above method. Hereinafter, the positive electrode plate and the precursor for producing the negative electrode plate will be specifically described.

(Precursor for producing positive electrode plate)
In the case of producing a positive electrode plate of a non-aqueous electrolyte secondary battery by the method of the present invention, as the electrode active material particles contained in the precursor, conventionally known various positive electrode active material particles that can be charged and discharged are used. It can be appropriately selected and used, and is not particularly limited. Examples of such positive electrode active material particles include LiCoO ₂ , LiMn ₂ O ₄ , LiNiO ₂ , LiFeO ₂ , Li ₄ Ti ₅ O ₁₂ , LiFePO ₄ , LiNi _1/3 Mn _1/3 Co _1/3 O _2. And positive electrode active material particles such as lithium transition metal composite oxides such as LiNi _0.80 Co _0.15 Al _0.05 O ₂ .

Among these positive electrode active material particles, LiMn ₂ O ₄ can be particularly preferably used. Since LiMn ₂ O ₄ has particularly high rate characteristics among various positive electrode active materials, the rate characteristics can be improved and the charge / discharge speed can be increased.

  Further, these positive electrode active material particles may be primary particles or secondary particles. Further, the particle diameter is not particularly limited, and those having an arbitrary size can be appropriately selected and used.

  In addition, when the positive electrode plate is produced by the method of the present invention, the metal element-containing compound contained in the precursor is any one selected from a lithium element-containing compound and cobalt, nickel, manganese, iron, or titanium. One or more metal element-containing compounds containing a metal element can be preferably used. The metal element-containing compound may be an inorganic metal element-containing compound that does not contain carbon in the compound, or may be an organometallic element-containing compound that contains carbon in the compound. Good. In the present invention and the present specification, the inorganic metal element-containing compound and the organic metal-containing compound may be simply referred to as a metal element-containing compound.

  In addition, examples of the metal element-containing compound include chlorides, nitrates, sulfates, perchlorates, acetates, phosphates, bromates, and the like of other metal elements such as lithium element and cobalt. Among them, in the present invention, chloride, nitrate, and acetate are preferably used because they are easily available as general-purpose products. In particular, nitrate is preferably used because of its good film-forming property for a wide variety of positive electrode current collectors.

For example, as a metal element-containing compound for producing LiCoO ₂ as a metal oxide, a Li element-containing compound and a Co element-containing compound can be used in combination as main raw materials, and other raw materials as necessary Can also be used in combination. Examples of the Li element-containing compound include lithium citrate tetrahydrate, lithium perchlorate trihydrate, lithium acetate dihydrate, lithium nitrate, and lithium phosphate. Examples of the compound include cobalt (II) chloride hexahydrate, cobalt (II) formate dihydrate, cobalt (III) acetylacetonate, cobalt (II) acetylacetonate dihydrate, cobalt acetate (II ) Tetrahydrate, cobalt (II) oxalate dihydrate, cobalt (II) nitrate hexahydrate, cobalt (II) ammonium chloride hexahydrate, sodium cobalt (III) nitrite, and cobalt sulfate ( II) The heptahydrate etc. are mentioned. The combination ratio (Li: Co = X: 1) of the Li element-containing compound and the Co element-containing compound used as the main raw material is not particularly limited, but is preferably 1 ≦ X <2, and preferably 1 ≦ X ≦ 1. 2 is more preferable.

Further, as the metal element-containing compounds to produce LiNiO ₂ as the metal oxide, Li-element-containing compound, and a Ni element-containing compound can be used in combination as the main raw material, and further, other ingredients as needed Can also be used in combination. Examples of the Li element-containing compound are the same as in the case of producing LiCoO ₂ described above. Examples of the Ni element-containing compound include nickel chloride (II) hexahydrate and nickel acetate (II) tetrahydrate. , Nickel (II) perchlorate hexahydrate, nickel (II) bromide trihydrate, nickel (II) nitrate hexahydrate, nickel (II) acetylacetonate dihydrate, hypophosphorous acid Examples thereof include nickel (II) acid hexahydrate and nickel (II) sulfate hexahydrate. The combination ratio (Li: Ni = X: 1) of the Li element-containing compound and Ni element-containing compound used as the main raw material is not particularly limited, but is preferably 1 ≦ X <2, and preferably 1 ≦ X ≦ 1. 2 is more preferable.

In addition, as a metal element-containing compound for generating LiMn ₂ O ₄ as a metal oxide, a Li element-containing compound and a Mn element-containing compound can be used in combination as main raw materials. These raw materials can also be used in combination. Examples of the Li element-containing compound are the same as in the case of producing LiCoO ₂ described above, and examples of the Mn element-containing compound include manganese acetate (III) dihydrate and manganese nitrate (II) hexahydrate. Products, manganese (II) sulfate pentahydrate, manganese (II) oxalate dihydrate, manganese (III) acetylacetonate, and the like. The combination ratio (Li: Mn = X: 1) of the Li element-containing compound and the Mn element-containing compound used as the main raw material is not particularly limited, but is preferably 0.5 ≦ X <1, 0.5 ≦ More preferably, X ≦ 0.6.

Further, as the metal element-containing compounds to produce LiFeO ₂ as the metal oxide, Li-element-containing compound, and a Fe element-containing compound can be used in combination as the main raw material, and further, other ingredients as needed Can also be used in combination. Examples of the Li element-containing compound are the same as in the case of producing LiCoO ₂ described above. Examples of the Fe element-containing compound include iron (II) chloride tetrahydrate, iron (III) citrate, and acetic acid. Examples include iron (II), iron (II) oxalate dihydrate, iron (III) nitrate nonahydrate, iron (II) lactate trihydrate, and iron (II) sulfate heptahydrate. . The combination ratio (Li: Fe = X: 1) of the Li element-containing compound and the Fe element-containing compound used as the main raw material is not particularly limited, but is preferably 1 ≦ X <2, and preferably 1 ≦ X ≦ 1. 2 is more preferable.

In addition, as a metal element-containing compound for producing Li ₄ Ti ₅ O ₁₂ as a metal oxide, a Li element-containing compound and a Ti element-containing compound can be used in combination as main raw materials, and if necessary, Other raw materials can also be used in combination. Examples of the Li element-containing compound are the same as in the case of producing LiCoO ₂ described above, and examples of the Ti element-containing compound include titanium tetrachloride and titanium acetylacetonate. The combination ratio (Li: Ti = X: 1) of the Li element-containing compound and the Ti element-containing compound used as the main raw material is not particularly limited, but is preferably 1 ≦ X <2, preferably 1 ≦ X ≦ 1. 2 is more preferable.

  The compounding ratio of the electrode (positive electrode) active material particles and the metal element-containing compound contained in the precursor for producing the positive electrode plate is not particularly limited, but the metal element-containing compound is a metal that undergoes a heating process. Since it becomes an oxide and the electrode (positive electrode) active material particles and the electrode (positive electrode) active material particles and the current collector are fixed by this metal oxide, when the content of the metal oxide is too small, There is a possibility that the fixing force cannot be increased to a desired level, or that the impedance cannot be decreased to a desired level. Therefore, in the state where the precursor finally becomes the positive electrode active material layer, the mass ratio of the metal oxide when the mass ratio of the electrode (positive electrode) active material particles is 100 parts by mass is 1 part by mass or more. It is preferable to adjust the blending ratio of the electrode (positive electrode) active material particles and the metal element-containing compound contained so as to be 100 parts by mass or less.

  Here, in forming the precursor for producing the positive electrode plate, the electrode active material particles described above and the metal element-containing compound are mixed in a solvent to prepare a positive electrode active material layer forming liquid, In the case of forming the precursor by coating on the positive electrode current collector, any solvent can be used as long as it can dissolve the metal element-containing compound, and a conventionally known solvent is appropriately selected. Can be used. For example, water, lower alcohols such as NMP (N-methyl-2-pyrrolidone), methanol, ethanol, n-propanol, iso-propanol, n-butanol, iso-butanol, 2-butanol, t-butanol, acetylacetone, diacetyl And ketones such as benzoylacetone, ketoesters such as ethyl acetoacetate, ethyl pyruvate, ethyl benzoylacetate and ethyl benzoylformate, toluene, ethylene glycol, diethylene glycol, polyethylene glycol, and mixed solvents thereof.

  In addition, when the metal element-containing compound is dissolved in the solvent as described above, the total ratio of one or more metal element-containing compounds added to the solvent is 0.01 to 5 mol / L, especially 0.1 to 2 mol / L is preferred. By setting the concentration to 0.01 mol / L or more, the positive electrode current collector and the positive electrode active material layer generated from the precursor on the surface of the current collector can be satisfactorily adhered, and the electrode (positive electrode) The active material particles can be fixed. In addition, by setting the concentration to 5 mol / L or less, the positive electrode active material layer forming liquid can maintain a good viscosity enough to be applied to the surface of the positive electrode current collector, and a uniform coating film Can be formed.

  Furthermore, when using the positive electrode active material layer forming liquid as described above, the forming liquid may contain a conductive material, an organic substance that is a viscosity adjusting agent of the forming liquid, or other additives.

  The thickness of the precursor is not particularly limited, but is generally about 15 to 300 μm.

(Precursor for producing negative electrode plate)
On the other hand, the electrode active material particles contained in the precursor in the case of producing a negative electrode plate of a nonaqueous electrolyte secondary battery by the method of the present invention include, for example, titanium cobalt oxide, manganese, iron, cobalt Examples thereof include materials capable of occluding and releasing lithium ions, such as nitrides and composite oxides containing lithium and titanium elements (for example, Li ₄ Ti ₅ O ₁₂ , Li ₂ Ti ₃ O ₇ ). Especially, in this invention, a lithium titanium complex oxide with a high rate characteristic can be used conveniently.

  In addition, in the case of producing a negative electrode plate by the method of the present invention, the metal element-containing compound contained in the precursor includes metal element chloride, nitrate, acetate, perchlorate, phosphate, bromate Examples thereof include metal salts such as salts, and hydrates of these metal salts. Among them, chlorides, nitrates, and acetates are easily available as general-purpose products, and chlorine ions, nitrate ions, and acetate ions can be easily eliminated from the precursor by heating in the heating process described later. Since it can be used, it can be particularly preferably used.

  More specifically, for example, when the metal element is copper, copper chloride, copper nitrate, copper acetate, copper acetate (II) monohydrate and the like can be mentioned, and when the metal element is nickel Can include nickel chloride, nickel nitrate, nickel acetate, nickel (II) nitrate hexahydrate, nickel acetate (II) tetrahydrate, and the like. When the metal element is lithium, lithium chloride , Lithium nitrate, lithium acetate, lithium acetate trihydrate and the like.

  The blending ratio of the electrode (negative electrode) active material particles and the metal element-containing compound contained in the precursor for producing the negative electrode plate is not particularly limited, but is the same reason for producing the positive electrode plate. Thus, in a state where the precursor finally becomes the negative electrode active material layer, the mass ratio of the metal oxide when the mass ratio of the electrode (negative electrode) active material particles is 100 parts by mass is 1 part by mass or more. It is preferable to adjust the blending ratio of the electrode (negative electrode) active material particles and the metal element-containing compound contained so as to be 100 parts by mass or less.

  In addition, the precursor for producing the negative electrode plate is prepared by preparing a negative electrode active material layer forming liquid and applying it onto the negative electrode current collector, as in the case of the positive electrode plate described above. As the solvent used for this, the same solvent as the positive electrode plate can be used. In that case, the ratio of the total amount of the one or more metal element-containing compounds added to the solvent is preferably 0.01 to 20 mol / L, particularly preferably 0.1 to 10 mol / L. By setting the concentration to 0.01 mol / L or more, the negative electrode current collector and the negative electrode active material layer produced from the precursor on the current collector surface can be satisfactorily adhered, and the negative electrode active material particles Adhesion to the current collector can be sufficiently achieved. In addition, by setting the concentration to 20 mol / L or less, the negative electrode active material layer forming liquid can be maintained at a satisfactory viscosity so that the negative electrode current collector surface can be satisfactorily applied, and a uniform coating film can be formed. Can be formed.

  The thickness of the precursor is not particularly limited, but is generally about 15 to 300 μm.

(3) Heating step In the method of the present invention, the heating step refers to the current collector on which the precursor after the precursor forming step (2) is formed, and the metal element-containing compound in the precursor is a metal oxide. The process of heating at a temperature equal to or higher than

The heating temperature is not particularly limited as long as it is equal to or higher than the temperature at which the metal element-containing compound in the precursor becomes a metal oxide. For example, in the production of a positive electrode plate, the metal element-containing compound contained in the precursor Are Li (CH ₃ COO) · 2H ₂ O and Mn (CH ₃ COO) ₂ · 4H ₂ O, the heating temperature is about 400 ° C., and the metal is heated by heating at that temperature. element-containing compound is thermally decomposed, LiMn ₂ O ₄ becomes a metal oxide, by the LiMn ₂ O _4, the positive electrode active material particles and the current collector, and fixing of the positive electrode active material particles with each other is achieved.

  For example, in the production of the negative electrode plate, when the metal element-containing compound contained in the precursor is copper nitrate, the heating temperature is about 270 ° C., and the metal element is heated by heating at the temperature. Copper nitrate which is a contained compound becomes copper oxide, and the negative electrode active material particles, the current collector, and the negative electrode active material particles are fixed to each other by the copper oxide.

  Further, the heating method is not particularly limited as long as it is a heating method or a heating apparatus that can be heated at a temperature equal to or higher than the temperature at which the metal element-containing compound becomes a metal oxide. For example, a method of using any one of a hot plate, an oven, a heating furnace, an infrared heater, a halogen heater, a hot air blower, etc., or a combination of two or more can be mentioned.

  Further, the heating atmosphere in the heating step is not particularly limited, and may be appropriately determined in consideration of the material used for manufacturing the positive electrode plate and the negative electrode plate, the heating temperature, the oxygen potential of the metal element-containing compound, and the like. it can. For example, an air atmosphere is preferable in that a special atmosphere adjustment is not necessary and the heating process can be easily performed. In particular, in the present invention, since aluminum is used as a current collector, even if the heating step is performed in an air atmosphere, there is no possibility that the aluminum is oxidized, and therefore the heating step can be preferably performed.

  Although the method of the present invention has been described with a focus on a production method in which a resinous binder is not contained as the best embodiment, this does not prohibit the inclusion of a resinous binder. For example, a resin binder is contained in the precursor, or the electrode plate after the heating step is immersed in an immersion tank filled with a resin mixture prepared by mixing a resin binder with an NMP solvent or the like. Thus, the electrode plate formed by the method of the present invention can contain a resin binder. Even when a resin binder is contained, it goes without saying that the input / output characteristics are improved and the battery capacity is increased by the amount of the metal oxide.

  Next, the present invention will be described more specifically with reference to examples and comparative examples. Hereinafter, unless otherwise specified, parts or% is based on mass.

Example 1
Li (CH ₃ COO) · 2H ₂ O [molecular weight: 102.02]: 2 g and Mn (CH ₃ COO) ₂ · 4H ₂ O [molecular weight: 245.09]: 10 g added to methanol: 12 g The raw material liquid for mixing and forming a metal oxide was used. Next, 10 g of the above raw material liquid: 10 g of positive electrode active material particles having an average particle diameter of 4 μm: LiMn ₂ O ₄ : 10 g, acetylene black (Denka Black, manufactured by Denki Kagaku Kogyo Co., Ltd.): 1.2 g, carbon fiber (Showa Denko) (VGCF) 0.25g, resin hydroxyethyl cellulose 0.2g dissolved in pure water 9.8g, 15g thickener aqueous solution and solvent methanol were mixed, and 8000rpm with Excel Auto Homogenizer (Nippon Seiki Seisakusho Co., Ltd.). The positive electrode active material layer forming liquid was prepared by kneading for 15 minutes at a rotational speed of.

Next, a surface treatment is performed by irradiating the surface of the aluminum foil having a thickness of 15 μm with vacuum ultraviolet light from an excimer lamp having a central wavelength of 172 nm for 15 minutes at an integrated irradiation amount of 1800 mJ / cm ² on the current collector surface. A current collector 1 having a carbon element number / aluminum element number of 126% at an element abundance ratio obtained from the peak of carbon: 1s and aluminum: 2p by electron spectroscopy is prepared, and the electrode active material layer forming liquid prepared above is prepared. Then, the electrode mass of the electrode active material layer finally obtained was applied to one side of the current collector with an applicator in such an amount that the electrode mass was 82 g / m ² to form a coating film for forming an electrode active material layer. Subsequently, the coating film was pressed using a roll press machine (manufactured by Sank Metal Co., Ltd .: mechanical type 1 ton) under the conditions of applied pressure: 0.1 ton / cm and pressing speed of 10 mm / second. Thereafter, the current collector with the electrode active material layer-forming coating film formed thereon was placed in a normal temperature electric furnace (muffle furnace, Denken, P90) and heated from room temperature to 450 ° C. over 20 minutes. Thus, a positive electrode plate for a non-aqueous electrolyte secondary battery in which a positive electrode active material layer was laminated on the current collector was obtained. And the said positive electrode plate was taken out from the electric furnace, and it was left until it became room temperature, and the positive electrode plate 1 of Example 1 with which the positive electrode active material layer was laminated | stacked on the positive electrode collector was obtained.

  In addition, in the element existence ratio obtained from the peak of carbon: 1s and aluminum: 2p by X-ray electron spectroscopy of the collector after the surface treatment, the number of carbon elements / number of aluminum elements is X-ray electron spectrometer (KRATOS) Elemental analysis of the surface was performed with ESCA-3400). The same applies to current collectors 2 to 16 below.

(Examples 2 to 5)
A current collector ² in which the irradiation time of Example 1 was changed to 5 minutes and the integrated irradiation amount was changed to 600 mJ / cm ² and the number of carbon elements / aluminum element was adjusted to 130%, and the irradiation time was set to 2 And the surface treatment for changing the integrated irradiation amount to 240 mJ / cm ² , the current collector 3 in which the number of carbon elements / aluminum element was adjusted to 139%, the irradiation time being 1 minute, and the integrated irradiation amount being 120 mJ / Surface treatment to change to cm ² , current collector 4 in which the number of carbon elements / aluminum element is adjusted to 143%, the same irradiation time for 30 seconds, and the surface treatment to change the integrated dose to 60 mJ / cm ² The positive electrode plates of Examples 2 to 5 were obtained in the same manner as in Example 1 except that the current collector 5 in which the number of carbon elements / the number of aluminum elements was adjusted to 148% was used.

(Example 6)
Surface treatment is performed by irradiating the surface of the aluminum foil with UV light from a low-pressure mercury lamp having a central wavelength of 254 nm for 20 minutes at an integrated irradiation amount of 1600 mJ / cm ² on the current collector surface, carbon by X-ray electron spectroscopy: 1 s, Aluminum: The positive electrode plate of Example 6 was prepared in the same manner as in Example 1 except that the current collector 6 having a carbon element number / aluminum element number of 130% in the element abundance ratio obtained from the peak of 2p was used. Obtained.

(Examples 7 and 8)
The current collector 7 in which the irradiation time in Example 6 was changed to 4 minutes and the integrated irradiation amount was changed to 320 mJ / cm ² , the number of carbon elements / the number of aluminum elements was adjusted to 139%, and the irradiation time was 2 Min, the surface dose is changed to 160 mJ / cm ² , and the number of carbon elements / number of aluminum elements is 148% in the element abundance ratio obtained from the peaks of carbon: 1s and aluminum: 2p by X-ray electron spectroscopy. Except for using the current collector 8 adjusted to, positive electrode plates of Examples 7 and 8 were obtained in the same manner as Example 6.

Example 9
Surface treatment is performed by plasma treatment in a mixed gas of hydrogen and nitrogen for 7 minutes, and the number of carbon elements / number of aluminum elements is 127 in the element abundance ratio obtained from the peaks of carbon: 1s and aluminum: 2p by X-ray electron spectroscopy. A positive electrode plate of Example 9 was obtained in the same manner as Example 1 except that% current collector 9 was used.

(Examples 10 and 11)
Surface treatment for changing the plasma treatment time in Example 9 to 1 minute, current collector 10 in which the number of carbon elements / aluminum element was adjusted to 135%, and surface treatment for changing the plasma treatment time to 6 seconds Except for using current collector 11 in which the number of carbon elements / the number of aluminum elements is adjusted to 148% in the element abundance ratio obtained from the peak of carbon: 1s and aluminum: 2p by X-ray electron spectroscopy In the same manner as in Example 9, positive electrode plates of Examples 10 and 11 were obtained.

(Example 12)
The clearance is set to 12 mm, the surface of the current collector is subjected to a corona treatment for 30 seconds, and the number of carbon elements / aluminum in the element abundance ratio obtained from the peaks of carbon: 1s and aluminum: 2p by X-ray electron spectroscopy. A positive electrode plate of Example 12 was obtained in the same manner as Example 1 except that the current collector 12 having 130% of elements was used.

(Examples 13 and 14)
Surface treatment in which the irradiation time in Example 12 was changed to 5 seconds, the current collector 13 having the number of carbon elements / aluminum element adjusted to 137%, the irradiation time was changed to 5 seconds, and the clearance was changed to 25 mm Except for using the current collector 14 in which the number of carbon elements / the number of aluminum elements was adjusted to 148% in the element abundance ratio obtained from the peak of carbon: 1s, aluminum: 2p by X-ray electron spectroscopy, All were carried out similarly to Example 12, and the positive electrode plate of Examples 13 and 14 was obtained.

(Comparative Example 1)
The current collector 15 was used in which the number of carbon elements / the number of aluminum elements was 169% in the element abundance ratio obtained from the peak of carbon: 1s and aluminum: 2p by X-ray electron spectroscopy without performing surface treatment of the current collector. A positive electrode plate of Comparative Example 1 was obtained in the same manner as Example 1 except for the above.

(Comparative Example 2)
The irradiation time and irradiation amount in Example 6 were changed to the irradiation time and irradiation amount shown in Table 1 below, and in the element abundance ratio obtained from the peaks of carbon: 1s and aluminum: 2p by X-ray electron spectroscopy, the number of carbon elements / A positive electrode plate of Comparative Example 2 was obtained in the same manner as in Example 6 except that the current collector 16 in which the number of aluminum elements was adjusted to 152% was used.

(Peel strength test 1)
The positive electrode plates of Examples 1 to 14 and Comparative Example 1 were stored at a temperature of 25 ° C. and a humidity of 40% for 6 hours, and a peel strength test was performed. The results are summarized in Table 1. The peel strength test was performed by the following method. The positive electrode plate is cut into a rectangular shape having a width of 2.5 cm and a length of 10 cm to form a test piece, which is fixed with the positive electrode active material layer surface facing up. After the cellophane tape was applied to the surface of the positive electrode active material layer of the test piece, the stress was measured when the cellophane tape was peeled off from the end of the test piece in the 90 ° direction at a speed of 50 mm / min. The measurement was performed 10 times, the average value was obtained, and this was taken as the peel strength.

(Peel strength test 2)
Instead of the peel strength test 1, the positive plates of Examples 1 and 9 and Comparative Example 1 were stored at a temperature of 45 ° C. and a humidity of 90% for 6 hours, and a peel strength test 2 was performed. The results are also shown in Table 1. The peel strength test 2 was performed in the same manner as the peel strength test 1.

<Production of tripolar coin cell>
Lithium hexafluorophosphate (LiPF ₆ ) is added as a solute to a mixed solvent of ethylene carbonate (EC) / dimethyl carbonate (DMC) (volume ratio = 1: 1), and the concentration of LiPF _{6 as} the solute is 1 mol. The non-aqueous electrolyte was prepared by adjusting the concentration to be / L. Using the examples and comparative examples prepared as described above as the positive electrode plate as the working electrode, the metal lithium plate as the counter electrode plate and the reference electrode plate, the non-aqueous electrolyte prepared above as the electrolyte, The assembly was subjected to the following charge / discharge test.

(Charge test)
The test cells of each Example and Comparative Example were charged with a constant current at a constant current (charge rate: 0.2 C) under a 25 ° C. environment until the voltage reached 4.3V. After the voltage reaches 4.3V, the current (charge rate: 0.2C) is reduced to 5% or less so that the voltage does not exceed 4.3V, and charging is performed at a constant voltage. The battery was fully charged and rested for 10 minutes. Here, the above-mentioned “0.2C” means a current value (current value reaching the discharge end voltage) at which the constant current discharge is performed using the tripolar coin cell and the discharge is completed in 5 hours.

(Discharge test)
Thereafter, the test cells of each of the fully charged Examples and Comparative Examples were kept at a constant current until the voltage was changed from 4.3 V (full charge voltage) to 3.0 V (discharge end voltage) in an environment of 25 ° C. (Discharge rate: 0.2 C) Constant current discharge, cell voltage (V) on the vertical axis, discharge time (h) on the horizontal axis, a discharge curve is created, and the discharge capacity (mAh) of the working electrode is obtained. The discharge capacity (mAh / g) per unit active material mass of the working electrode was converted.

(Cycle test)
After confirming the capacity, a cycle test in which CC + CV charge and CC discharge were repeated at a charge / discharge rate of 1 C was performed, and the cycle number in which the discharge capacity was less than 80% of the initial discharge capacity was defined as the cycle life in this test. The results are also shown in Table 1.

(Measurement of DC resistance)
In the case where the discharge test was performed under the condition of a discharge rate of 1 C using the test cells of the example and the comparative example, the voltage value (V1) (mV) 10 seconds after the start of the discharge was measured. Furthermore, the voltage value (V10) (mV) 10 seconds after the start of discharge was also measured when the discharge test was performed under the condition of the discharge rate 10C. Then, based on these measured values (V1, V10) and the constant current values (I1, I10) (mA) corresponding to the discharge rates 1C, 10C, the direct current resistance value (Ω) is calculated by the following equation 1. It was measured. The measurement results of the DC resistance value (Ω) are also shown in Table 1.

  As can be seen from the above table, the surface treatment was performed so that the number of carbon elements / number of aluminum elements was 148% or less in the element abundance ratio obtained from the peak of carbon: 1s and aluminum: 2p by X-ray electron spectroscopy. The examples using the aluminum current collector are excellent in adhesion and cycle characteristics. On the other hand, Comparative Examples 1 and 2 larger than 148% were inferior in all evaluation items as compared with Examples.

  In addition, the positive electrode plate of the example is a binding material made of a metal oxide, and the current collector, the electrode active material particles, and the electrode active material particles are fixed to each other. It turns out that it is excellent.

Claims (2)

The surface treatment of the current collector made of aluminum is performed so that the number of carbon elements / number of aluminum elements is 148% or less in the element abundance ratio obtained from the peaks of carbon: 1s and aluminum: 2p by X-ray electron spectroscopy. Surface treatment process;
After the surface treatment step, forming a precursor containing at least electrode active material particles and a metal element-containing compound on the current collector;
Heating at a temperature at which the metal element-containing compound in the precursor becomes a metal oxide or higher,
The manufacturing method of the electrode plate for nonaqueous electrolyte secondary batteries which has this.   The method for producing an electrode plate for a non-aqueous electrolyte secondary battery according to claim 1, wherein the surface treatment step is a treatment for degreasing the current collector made of aluminum.