JP2017050112A - Method for manufacturing nonaqueous secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for efficiently manufacturing a nonaqueous secondary battery with an SEI coating formed on a negative electrode mixture layer while suppressing the worsening of a battery performance.SOLUTION: A method for manufacturing a nonaqueous secondary battery comprises: an assembly step in which a positive electrode, a negative electrode and an electrolytic solution are put in a battery container to assemble an uncharged nonaqueous secondary battery; a heating step in which the uncharged nonaqueous secondary battery is heated at 40°C or higher; and an initial charging step in which the uncharged nonaqueous secondary battery is charged after the heating step. The negative electrode has a negative electrode mixture layer including a negative electrode active material, a water-insoluble polymer and a water-soluble polymer. The water-insoluble polymer is over 1.0 to 4.0 or less times in swelling degree in the electrolytic solution, and 80 to 95 mass% in gel amount. The water-soluble polymer is over 1.0 to 2.0 or less times in swelling degree in the electrolytic solution.SELECTED DRAWING: None

Description

  The present invention relates to a method for producing a non-aqueous secondary battery.

  Non-aqueous secondary batteries (non-aqueous electrolyte secondary batteries) such as lithium ion secondary batteries are small and lightweight, have high energy density, and can be repeatedly charged and discharged, and are used in a wide range of applications. ing. Therefore, in recent years, various studies have been made for the purpose of further improving the performance of non-aqueous secondary batteries.

  Specifically, for example, an electrode mixture layer (positive electrode mixture layer or negative electrode mixture layer) including an electrode active material (positive electrode active material or negative electrode active material) and a binder is formed on the current collector. For a non-aqueous secondary battery using an electrode (positive electrode or negative electrode), the life characteristics of the non-aqueous secondary battery are improved by forming a SEI (Solid Electrolyte Interphase) film on the surface of the negative electrode mixture layer. It has been tried.

  And conventionally, when manufacturing a non-aqueous secondary battery, the SEI film is charged with an electrolyte solution by charging the assembled secondary battery to a predetermined charging depth (SOC; State of Charge) (initial charging process). The electrolyte is reduced and decomposed at the interface with the negative electrode mixture layer to form on the negative electrode mixture layer (see, for example, Patent Documents 1 and 2). In the conventional non-aqueous secondary battery manufacturing method, after the initial charging process, the non-aqueous secondary battery is warmed and stored for a predetermined time (aging process), thereby forming the formed SEI film into a high-quality film. It has been modified.

Japanese Patent Application Laid-Open No. 2014-238961 JP-A-2015-95334

  By the way, in recent years, it has been studied to increase the density of the electrode mixture layer from the viewpoint of further increasing the energy density of the non-aqueous secondary battery and providing a higher-performance non-aqueous secondary battery.

  However, when the electrode mixture layer is densified, the electrolyte solution hardly penetrates into the electrode mixture layer when the non-aqueous secondary battery is assembled. Therefore, when a non-aqueous secondary battery in which the electrode mixture layer, particularly the negative electrode mixture layer is densified, is subjected to the above-described conventional initial charging treatment and aging treatment to form an SEI film, the negative electrode mixture layer is formed. Due to the insufficient penetration of the electrolyte solution, poor formation of the SEI film and metal deposition on the negative electrode occurred, and the battery performance sometimes deteriorated. On the other hand, when the initial charging process is performed after the electrolyte solution is sufficiently infiltrated into the electrode mixture layer that has been densified by leaving the assembled non-aqueous secondary battery for a long time, the formation of the SEI film is poor. Although the occurrence of metal deposition can be suppressed, the production efficiency of the non-aqueous secondary battery is reduced.

  For such problems, for example, by promoting the penetration of the electrolytic solution into the electrode mixture layer by using means such as heating before the initial charging treatment, the formation of SEI film and the occurrence of metal deposition are prevented. It is also conceivable to efficiently manufacture a non-aqueous secondary battery while suppressing it.

  However, when the non-aqueous secondary battery is heated before the initial charging process, that is, before the formation of the SEI film, the negative electrode mixture layer may be peeled off or cracked, resulting in a decrease in battery performance.

  Accordingly, the present invention provides a non-deposited SEI film formed on the negative electrode mixture layer while suppressing deterioration in battery performance even when the electrode mixture layer (particularly the negative electrode mixture layer) is densified. An object of the present invention is to provide a technology that makes it possible to efficiently manufacture an aqueous secondary battery.

  The present inventors have intensively studied to achieve the above object. And if the present inventors used together the water-insoluble polymer and water-soluble polymer which have a predetermined | prescribed property as a binder of a negative electrode compound-material layer, it heated before carrying out initial charge of a non-aqueous secondary battery. Even in this case, it was found that peeling and cracking of the negative electrode composite material layer could be suppressed, and the present invention was completed.

That is, the present invention aims to advantageously solve the above-mentioned problems, and the non-aqueous secondary battery manufacturing method of the present invention contains a positive electrode, a negative electrode, and an electrolytic solution in a battery container. An assembling process for assembling the uncharged non-aqueous secondary battery, a heating process for heating the uncharged non-aqueous secondary battery to 40 ° C. or higher, and an initial charging process for charging the uncharged non-aqueous secondary battery after the heating process. The negative electrode includes a negative electrode mixture layer containing a negative electrode active material, a water-insoluble polymer, and a water-soluble polymer. The water-insoluble polymer has an electrolyte swelling degree of more than 1.0 times 4 0.0 times or less, the gel amount is 80% by mass or more and 95% by mass or less, and the water-soluble polymer has an electrolyte solution swelling degree of more than 1.0 times and 2.0 times or less.
In this way, if the uncharged non-aqueous secondary battery is heated to 40 ° C. or more before initial charging, the electrolyte solution can be mixed with the negative electrode without leaving the uncharged non-aqueous secondary battery for a long time. It can penetrate well into the material layer. Therefore, when the initial charging is performed later, the SEI film can be favorably formed on the negative electrode surface. Further, if the negative electrode mixture layer contains a water-insoluble polymer having a predetermined degree of electrolyte swelling and a gel amount and a water-soluble polymer having a predetermined degree of electrolyte swelling, an uncharged non-aqueous secondary layer Even when the battery is heated before initial charging, it is possible to suppress the peeling and cracking of the negative electrode mixture layer. Therefore, a non-aqueous secondary battery having excellent battery performance can be manufactured.
In the present invention, the “temperature” for heating the non-charged non-aqueous secondary battery is not particularly limited as long as it can be measured as the ambient temperature around the battery assembly. For example, the temperature can be adjusted and the actual temperature can be adjusted. It can be measured using a thermostat capable of measurement.
In the present invention, the “electrolyte swelling degree” and the “gel amount” can be measured using the measuring methods described in the examples of the present specification.
Further, in the present invention, the “water-soluble polymer” refers to a polymer having an insoluble content of less than 1.0% by mass when 0.5 g of the polymer is dissolved in 100 g of water at a temperature of 25 ° C. In the present invention, the “water-insoluble polymer” refers to a polymer having an insoluble content of 90% by mass or more when 0.5 g of the polymer is dissolved in 100 g of water at 25 ° C.

Here, in the method for producing a non-aqueous secondary battery of the present invention, the negative electrode active material preferably has a tap density of 0.8 g / cm ³ or more and 1.2 g / cm ³ or less. If a negative electrode active material having a tap density within the above range is used, a negative electrode mixture layer having a high density and strength and allowing easy penetration of the electrolytic solution can be obtained.
In the present invention, the “tap density” of the negative electrode active material can be measured using the measurement method described in the examples of the present specification.

In the method for producing a non-aqueous secondary battery according to the present invention, the density of the negative electrode mixture layer is preferably 1.60 g / cm ³ or more. If the manufacturing method of the present invention is used, a non-aqueous secondary battery in which a SEI film is formed on the negative electrode mixture layer while suppressing a decrease in battery performance even when the density of the negative electrode mixture layer is high. It can be manufactured efficiently.
In the present invention, the “density” of the negative electrode mixture layer can be calculated using the mass and thickness of the negative electrode mixture layer per unit area.

Furthermore, in the method for producing a non-aqueous secondary battery of the present invention, the negative electrode mixture layer has a water-insoluble polymer in a ratio of 0.5 parts by mass or more and 4 parts by mass or less per 100 parts by mass of the negative electrode active material; It is preferable to contain a water-soluble polymer in a proportion of 5 parts by mass or more and 3 parts by mass or less.
By making the blending amount of the water-insoluble polymer and the water-soluble polymer in the above range, the increase in the internal resistance is suppressed while increasing the strength of the negative electrode mixture layer, and a non-aqueous secondary battery with excellent battery performance is manufactured. can do.

In the non-aqueous secondary battery manufacturing method of the present invention, the uncharged non-aqueous secondary battery further includes a separator between the negative electrode and the positive electrode, and the uncharged non-aqueous secondary battery is heated at 60 ° C. for 15 hours. It is preferable that the adhesive force between the negative electrode and the separator when left to stand is 1.0 N / m or less.
Thus, by reducing the adhesive force between the negative electrode and the separator, the negative electrode mixture layer is prevented from peeling off due to the expansion and contraction of the negative electrode active material accompanying charge / discharge, and the non-aqueous system is excellent in battery performance. A secondary battery can be manufactured.
The “adhesive strength” between the negative electrode and the separator can be measured using the measuring method described in the examples of the present specification.

  ADVANTAGE OF THE INVENTION According to this invention, the nonaqueous secondary battery which formed the SEI membrane | film | coat on the negative mix layer can be manufactured efficiently, suppressing the fall of battery performance.

  Hereinafter, embodiments of the present invention will be described in detail.

(Method for producing non-aqueous secondary battery)
In the production method of the present invention, a non-aqueous secondary battery is produced in which a battery member including a positive electrode and a negative electrode and an electrolytic solution are accommodated in a battery container. In addition to the positive electrode and the negative electrode, the battery member accommodated in the battery container may include a known battery member such as a separator that separates the positive electrode and the negative electrode and prevents a short circuit between the positive electrode and the negative electrode. Good.
The manufacturing method of the present invention also includes an assembling process for assembling an uncharged non-aqueous secondary battery by housing a battery member and an electrolyte in a battery container, and heating the uncharged non-aqueous secondary battery to a predetermined temperature or higher. A heating step and an initial charging step of charging the uncharged non-aqueous secondary battery after the heating step. Furthermore, in the production method of the present invention, as the negative electrode, a negative electrode comprising a negative electrode mixture layer containing a negative electrode active material, a water-insoluble polymer having a predetermined property, and a water-soluble polymer having a predetermined property. use.
And according to the manufacturing method of the non-aqueous secondary battery of the present invention, since the heating step is performed before the initial charge of the uncharged non-aqueous secondary battery, the electrolyte solution into the negative electrode mixture layer before the initial charge The non-aqueous secondary battery in which the SEI film is formed on the negative electrode mixture layer can be efficiently manufactured while promoting the penetration of SEI and suppressing the formation failure of the SEI film and metal deposition on the negative electrode. In addition, according to the method for manufacturing a non-aqueous secondary battery of the present invention, since a water-insoluble polymer having a predetermined property and a water-soluble polymer are used, a heating step is performed before initial charging. Even so, it is possible to suppress the peeling and cracking of the negative electrode mixture layer. Therefore, according to the method for producing a non-aqueous secondary battery of the present invention, a non-aqueous secondary battery having a negative electrode composite layer on which a good SEI film is formed and having excellent battery characteristics such as life characteristics is efficiently produced. Can be manufactured automatically.

<Negative electrode>
The negative electrode of the non-aqueous secondary battery manufactured using the manufacturing method of the present invention is not particularly limited as long as it includes a predetermined negative electrode mixture layer. For example, a predetermined negative electrode mixture layer is collected. A negative electrode formed on an electric body can be used.

[Current collector]
Here, a known current collector can be used as the current collector. And as a material of an electrical power collector, since it has electrical conductivity, electrochemical durability, and heat resistance, a metal is preferable, for example, iron, copper, aluminum, nickel, stainless steel, titanium, tantalum, gold, Platinum or the like can be used.

[Negative electrode mixture layer]
The negative electrode mixture layer of the negative electrode used in the production method of the present invention contains a negative electrode active material, a water-insoluble polymer, and a water-soluble polymer.
Here, the density of the negative electrode material layer is preferably 1.60 g / cm ³ or more, more preferably 1.65 g / cm ³ or more, still be at 1.70 g / cm ³ or more Preferably, it is 2.0 g / cm ³ or less. When the density of the negative electrode mixture layer is 1.60 g / cm ³ or more, the energy density of the non-aqueous secondary battery can be sufficiently increased. In general, when the density of the negative electrode mixture layer is increased, the electrolyte does not easily penetrate into the negative electrode mixture layer. However, according to the manufacturing method of the present invention, since the heating step is performed before the initial charging step, the negative electrode mixture layer can be formed in a short time even when the density of the negative electrode mixture layer is 1.60 g / cm ³ or more. The electrolyte solution can be satisfactorily permeated into the composite material layer, and the formation failure of the SEI film and the occurrence of metal deposition due to insufficient permeation of the electrolyte solution can be suppressed.

[[Water-insoluble polymer]]
The water-insoluble polymer contained in the negative electrode mixture layer holds the components contained in the negative electrode mixture layer so as not to be detached from the negative electrode mixture layer, and the negative electrode mixture layer formed on the current collector has It is a component that can be held to bind well with the current collector.

-Properties of water-insoluble polymers-
The water-insoluble polymer contained in the negative electrode mixture layer needs to have an electrolyte swelling degree of more than 1.0 times and not more than 4.0 times. Is preferably 1.1 times or more, more preferably 1.3 times or more, preferably 3.0 times or less, and more preferably 2.0 times or less. If the degree of swelling of the electrolyte solution of the water-insoluble polymer is more than 1.0 times, the ion conductivity of the negative electrode mixture layer can be sufficiently secured, and the internal resistance of the secondary battery can be sufficiently lowered. Further, if the degree of electrolyte swelling of the water-insoluble polymer is 4.0 times or less, the strength of the negative electrode mixture layer is sufficiently increased, and even when the heating step is performed before the initial charging step, Generation | occurrence | production of the negative electrode compound material layer and a crack can be suppressed.
Note that the degree of swelling of the electrolytic solution can be controlled, for example, by adjusting the composition of the water-insoluble polymer.

Further, the water-insoluble polymer needs to have a gel amount of 80% by mass or more and 95% by mass or less, and the gel amount of the water-insoluble polymer is preferably 82% by mass or more. It is preferable that it is below mass%. If the gel amount of the water-insoluble polymer is 80% by mass or more and 95% by mass or less, the strength and flexibility of the negative electrode mixture layer is sufficiently increased, and the heating step is performed before the initial charging step. Moreover, it can suppress that peeling and a crack of a negative electrode compound material layer generate | occur | produce.
The gel amount can be controlled, for example, by adjusting the composition of the water-insoluble polymer, the polymerization temperature, and the amount and type of chain transfer agent used for the polymerization.

-Composition of water-insoluble polymer-
The water-insoluble polymer is not particularly limited as long as it has the above-described electrolyte swelling degree and gel amount, and any polymer such as a conjugated diene polymer or an acrylic polymer is used. be able to. Among these, as the water-insoluble polymer, a conjugated diene polymer is preferable, and a copolymer having an aromatic vinyl monomer unit and a conjugated diene monomer unit as main constituent units is more preferable. Here, “the aromatic vinyl monomer unit and the conjugated diene monomer unit are the main constituent units” means that the aromatic vinyl monomer unit and the conjugated diene monomer unit in the copolymer. It means that the total content exceeds 50% by mass of the total monomer units of the copolymer.

-Aromatic vinyl monomer unit-
Here, examples of the aromatic vinyl monomer that can form an aromatic vinyl monomer unit include styrene, α-methylstyrene, pt-butylstyrene, butoxystyrene, vinylnaphthalene, vinyltoluene, and chlorostyrene. Etc. Among these, styrene is preferable. These may be used alone or in combination of two or more.
And the ratio of the aromatic vinyl monomer unit in the copolymer is preferably 10% by mass or more, more preferably 30% by mass or more, still more preferably 50% by mass or more, It is preferably 80% by mass or less, more preferably 75% by mass or less, and further preferably 70% by mass or less. If the ratio of the aromatic vinyl monomer unit is 10% by mass or more, the electrolyte solution swelling degree of the water-insoluble polymer can be suppressed from being excessively increased, and the strength of the negative electrode mixture layer can be further increased. Because. Further, if the ratio of the aromatic vinyl monomer unit is 80% by mass or less, the toughness of the water-insoluble polymer can be increased, and the occurrence of cracking and peeling of the negative electrode mixture layer can be sufficiently suppressed. Because.

-Conjugated diene monomer unit-
Examples of the conjugated diene monomer that can form a conjugated diene monomer unit include 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 2-ethyl-1,3- Examples include butadiene, 1,3-pentadiene, 2-chloro-1,3-butadiene, and piperylene. Among these, 1,3-butadiene is preferable. These can be used alone or in combination of two or more.
The proportion of the conjugated diene monomer unit in the copolymer is preferably 20% by mass or more, more preferably 25% by mass or more, still more preferably 30% by mass or more, and 50 It is preferably at most mass%, more preferably at most 45 mass%, further preferably at most 40 mass%. When the ratio of the conjugated diene monomer unit is 20% by mass or more, it is possible to increase the gel amount of the copolymer and to suppress the electrolyte solution swelling degree from becoming excessively large. As a result, a negative electrode mixture layer having excellent flexibility and strength can be obtained. Moreover, if the ratio of the conjugated diene monomer unit is 50% by mass or less, the negative electrode composite material layer can have an appropriate hardness, and the strength of the negative electrode composite material layer can be sufficiently ensured.

-Other monomer units-
The copolymer having an aromatic vinyl monomer unit and a conjugated diene monomer unit as main constituent units is other monomer units other than the aromatic vinyl monomer unit and the conjugated diene monomer unit. May be included. Other monomer units are not particularly limited, for example, acidic group-containing monomer units such as unsaturated carboxylic acid monomer units, (meth) acrylic acid ester monomer units, nitrile group-containing A monomer unit etc. are mentioned. These may be used alone or in combination of two or more. In the present application, “(meth) acryl” means acryl and / or methacryl.

= Acid group-containing monomer unit =
Examples of unsaturated carboxylic acid monomers that can form unsaturated carboxylic acid monomer units that are acidic group-containing monomer units include unsaturated monocarboxylic acids and derivatives thereof, unsaturated dicarboxylic acids and acid anhydrides thereof. Products, and derivatives thereof. Examples of unsaturated monocarboxylic acids include acrylic acid, methacrylic acid, and crotonic acid. Examples of unsaturated monocarboxylic acid derivatives include 2-ethylacrylic acid, isocrotonic acid, α-acetoxyacrylic acid, β-trans-aryloxyacrylic acid, α-chloro-β-E-methoxyacrylic acid, and β -Diaminoacrylic acid. Examples of unsaturated dicarboxylic acids include maleic acid, fumaric acid, and itaconic acid. Examples of unsaturated dicarboxylic acid anhydrides include maleic anhydride, acrylic anhydride, methyl maleic anhydride, and dimethyl maleic anhydride. Examples of unsaturated dicarboxylic acid derivatives include methylmaleic acid, dimethylmaleic acid, phenylmaleic acid, chloromaleic acid, dichloromaleic acid, fluoromaleic acid, diphenyl maleate, nonyl maleate, decyl maleate, dodecyl maleate , Octadecyl maleate, fluoroalkyl maleate and the like. These can be used individually by 1 type or in combination of 2 or more types.

Among these, the unsaturated carboxylic acid monomer is preferably an unsaturated monocarboxylic acid such as acrylic acid or methacrylic acid, or an unsaturated dicarboxylic acid such as maleic acid, fumaric acid or itaconic acid, and acrylic acid or itaconic acid. Is more preferable, and itaconic acid is still more preferable.
The proportion of the acidic group-containing monomer unit in the copolymer is preferably 0.5% by mass or more, more preferably 1% by mass or more, and further preferably 2% by mass or more. Preferably, it is preferably 10% by mass or less, more preferably 8% by mass or less, and further preferably 6% by mass or less. This is because if the ratio of the acidic group-containing monomer unit is 0.5 mass% or more, the adhesion between the negative electrode active materials and between the current collector and the negative electrode mixture layer can be improved. On the other hand, if the ratio of the acidic group-containing monomer unit is 10% by mass or less, the negative electrode composite material layer can be sufficiently prevented from being cracked or peeled off.

= (Meth) acrylic acid ester monomer unit =
Examples of the (meth) acrylate monomer that can form a (meth) acrylate monomer unit include, for example, methyl (meth) acrylate, butyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate. , 2-hydroxyethyl acrylate. These can be used individually by 1 type or in combination of 2 or more types.

= Nitrile group-containing monomer unit =
Examples of the nitrile group-containing monomer that can form a nitrile group-containing monomer unit include α, β-ethylenically unsaturated nitrile monomers. Specifically, the α, β-ethylenically unsaturated nitrile monomer is not particularly limited as long as it is an α, β-ethylenically unsaturated compound having a nitrile group. For example, acrylonitrile; α-chloroacrylonitrile, α-halogenoacrylonitrile such as α-bromoacrylonitrile; α-alkylacrylonitrile such as methacrylonitrile and α-ethylacrylonitrile; and the like. Among these, (meth) acrylonitrile is preferable from the viewpoint of appropriately increasing the electrolyte swelling degree of the water-insoluble polymer to increase the ionic conductivity of the negative electrode mixture layer and reducing the internal resistance of the secondary battery. These can be used individually by 1 type or in combination of 2 or more types.

-Preparation method of water-insoluble polymer-
And the preparation method of the water-insoluble polymer using the monomer mentioned above is not specifically limited, For example, any methods, such as solution polymerization method, suspension polymerization method, block polymerization method, and emulsion polymerization method, should be used. Can do. As the polymerization method, addition polymerization such as ionic polymerization, radical polymerization, living radical polymerization and the like can be used.

-Content-
The amount of the water-insoluble polymer contained in the negative electrode mixture layer is preferably 0.5 parts by mass or more and more preferably 1.0 part by mass or more per 100 parts by mass of the negative electrode active material. Preferably, it is 1.5 parts by mass or more, more preferably 4 parts by mass or less, more preferably 3 parts by mass or less, and further preferably 2.5 parts by mass or less. If the content of the water-insoluble polymer having a predetermined degree of electrolyte swelling and gel amount is not less than the above lower limit, flexibility is imparted to the negative electrode mixture layer and sufficient strength of the negative electrode mixture layer is ensured. Because it can. In addition, if the content of the water-insoluble polymer having a predetermined degree of electrolyte swelling and a gel amount is not more than the above upper limit value, a low-internal resistance and high-capacity non-aqueous secondary battery can be obtained. is there.

[[Water-soluble polymer]]
The water-soluble polymer contained in the negative electrode mixture layer is held together with the above-mentioned water-insoluble polymer so that the components contained in the negative electrode mixture layer are not detached from the negative electrode mixture layer, and on the current collector. It is a component that can bind the negative electrode composite material layer formed on the current collector well.

-Properties of water-soluble polymer-
The water-soluble polymer needs to have an electrolyte solution swelling degree of more than 1.0 and 2.0 times or less, and the water-soluble polymer has an electrolyte solution swelling degree of 1.3 times or less. Preferably, it is 1.2 times or less, more preferably 1.1 times or less. When the degree of swelling of the electrolytic solution of the water-soluble polymer is more than 1.0 times, the ionic conductivity of the negative electrode mixture layer can be sufficiently secured, and the internal resistance of the secondary battery can be sufficiently lowered. Further, if the degree of swelling of the electrolytic solution of the water-soluble polymer is 2.0 times or less, the strength of the negative electrode mixture layer is sufficiently increased, and even when the heating step is performed before the initial charging step, the negative electrode The peeling and cracking of the composite material layer can be suppressed.
In addition, the electrolyte solution swelling degree of a water-soluble polymer can be controlled by adjusting the composition of the water-soluble polymer, for example.

-Composition of water-soluble polymer-
The water-soluble polymer is not particularly limited as long as it has the above-described degree of swelling of the electrolyte solution. For example, carboxymethyl cellulose (CMC), carboxyethyl cellulose, ethyl cellulose, hydroxymethyl cellulose, hydroxypropyl cellulose, carboxyethyl methyl cellulose Cellulose polymers such as cellulose compounds such as ammonium salts and alkali metal salts thereof; oxidized starch and phosphate starch; casein; various modified starches; polyethylene oxide, polyethylene glycol, polyvinyl alcohol, polyvinylpyrrolidone, polysulfonic acid , Polycarboxylic acids; (meth) acrylic acid copolymers, acrylamide polymers, and salts thereof such as ammonium salts and alkali metal salts Door can be. These may be used alone or in combination of two or more.

  Among them, as the water-soluble polymer, a cellulose polymer, a (meth) acrylamide polymer, and a combination thereof are preferable.

-Content-
The amount of the water-soluble polymer contained in the negative electrode mixture layer is preferably 0.5 parts by mass or more and more preferably 0.7 parts by mass or more per 100 parts by mass of the negative electrode active material. 0.8 parts by mass or more, more preferably 3 parts by mass or less, more preferably 2 parts by mass or less, and further preferably 1.5 parts by mass or less. If the content of the water-soluble polymer having a predetermined degree of electrolytic solution swelling is not less than the above lower limit value, the negative electrode mixture layer can be made to have an appropriate hardness, and the strength of the negative electrode mixture layer can be sufficiently secured. is there. Further, if the content of the water-soluble polymer having a predetermined degree of electrolyte swelling is not more than the above upper limit value, the internal resistance of the secondary battery is reduced, and a high-capacity non-aqueous secondary battery can be obtained. .

[[Negative electrode active material]]
The negative electrode active material contained in the negative electrode mixture layer is not particularly limited, and a known negative electrode active material can be used. Examples of known negative electrode active materials include carbon-based active materials, silicone-based active materials, and single metals and alloys that form lithium alloys when the non-aqueous secondary battery is a lithium ion secondary battery. . Among these, as the negative electrode active material, a carbon-based active material is preferable, a carbon-based active material using natural graphite is more preferable, and natural graphite is coated with a low crystalline carbon material (hereinafter referred to as “amorphous coating”). A carbon-based active material obtained by the following is more preferable. Examples of the amorphous coating method include the method disclosed in JP 2013-45714 A.

-Properties of negative electrode active material-
The negative electrode active material preferably has a tap density of 0.8 g / cm ³ or more, more preferably 0.85 g / cm ³ or more, still more preferably 0.9 g / cm ³ or more. preferably .2g / cm ³ or less, more preferably 1.1 g / cm ³ or less, further preferably 1.05 g / cm ³ or less. This is because if a negative electrode active material having a tap density of 0.8 g / cm ³ or more is used, a negative electrode including a negative electrode mixture layer having high density and strength can be easily obtained. Further, when a negative electrode active material having a tap density of 1.2 g / cm ³ or less is used, the electrolyte solution is more likely to penetrate into the negative electrode mixture layer.

  Further, the negative electrode active material preferably has a volume average particle diameter of 5 μm or more, more preferably 7 μm or more, further preferably 10 μm or more, preferably 30 μm or less, and preferably 25 μm or less. More preferably, it is more preferably 20 μm or less. In the present invention, the “volume average particle size” of the negative electrode active material is 50% using, for example, a laser diffraction / scattering type particle size distribution measuring apparatus (manufactured by Microtrack Bell, model number: Microtrack MT3000II). The diameter can be measured by a wet method.

  Here, the volume average particle diameter and tap density of the negative electrode active material can be controlled, for example, by spheroidizing negative or non-spherical negative electrode active material particles. A preferable method for the spheroidizing treatment is not particularly limited, and examples thereof include a method disclosed in JP 2010-34036 A. Specifically, the spheronization treatment is performed by applying an impact force or the like to the negative electrode active material particles dispersed in a high-speed air stream using, for example, a hybridization system (manufactured by Nara Machinery Co., Ltd., model number: NHS-3). It can be carried out.

[Preparation of negative electrode]
The negative electrode provided with the above-described negative electrode mixture layer is not particularly limited and can be produced using a known technique. Specifically, the negative electrode collects, for example, a negative electrode slurry composition including a negative electrode active material, a water-insoluble polymer, a water-soluble polymer, an optional additive, and a dispersion medium such as water. It can produce by apply | coating on a body and drying the apply | coated slurry composition for negative electrodes, and forming a negative mix layer. Note that the negative electrode mixture layer formed on the current collector may be subjected to pressure treatment such as pressing to adjust the density.
Further, the water-insoluble polymer is usually present in a particle shape in the negative electrode slurry composition, but in the formed negative electrode mixture layer, it may be in a particle shape or in any other shape. There may be.

<Positive electrode>
As the positive electrode of the non-aqueous secondary battery manufactured using the manufacturing method of the present invention, a known positive electrode can be used. Specifically, the positive electrode is not particularly limited, and a positive electrode having a current collector and a positive electrode mixture layer formed on the current collector can be used. The positive electrode mixture layer usually contains a positive electrode active material, a conductive material, and a binder.
Here, as the current collector, the positive electrode active material in the positive electrode mixture layer, the conductive material, and the binder, and a method for forming the positive electrode mixture layer on the current collector, a known method may be used. For example, those described in JP2013-145663A can be used.

<Electrolyte>
As the electrolytic solution of the non-aqueous secondary battery manufactured using the manufacturing method of the present invention, a known electrolytic solution can be used. Specifically, when the non-aqueous secondary battery is a lithium ion secondary battery, for example, a non-aqueous solvent in which a lithium salt is dissolved as a supporting electrolyte can be used. Examples of the lithium salt include LiPF ₆ , LiAsF ₆ , LiBF ₄ , LiSbF ₆ , LiAlCl ₄ , LiClO ₄ , CF ₃ SO ₃ Li, C ₄ F ₉ SO ₃ Li, CF ₃ COOLi, (CF ₃ CO) ₂ NLi , (CF ₃ SO ₂ ) ₂ NLi, (C ₂ F ₅ SO ₂ ) NLi, and other lithium salts. In particular, LiPF ₆ , LiClO ₄ , and CF ₃ SO ₃ Li that are easily soluble in a solvent and exhibit a high degree of dissociation are preferably used. In addition, electrolyte may be used individually by 1 type and may be used combining two or more types by arbitrary ratios. Usually, the lithium ion conductivity tends to increase as the supporting electrolyte having a higher degree of dissociation is used, so that the lithium ion conductivity can be adjusted depending on the type of the supporting electrolyte.
The solvent used in the electrolytic solution is not particularly limited as long as it can dissolve the supporting electrolyte. Usually, dimethyl carbonate (DMC), ethylene carbonate (EC), diethyl carbonate (DEC), propylene carbonate (PC), butylene. Alkyl carbonates such as carbonate (BC) and ethyl methyl carbonate (EMC); esters such as γ-butyrolactone and methyl formate; ethers such as 1,2-dimethoxyethane and tetrahydrofuran; sulfolane and dimethyl sulfoxide Of sulfur-containing compounds are used. Moreover, it is also possible to use an electrolyte containing an additive. As the additive, carbonate compounds such as vinylene carbonate (VC) are preferable.

<Separator>
As a separator which the non-aqueous secondary battery manufactured using the manufacturing method of the present invention optionally includes, a known separator can be used without any particular limitation. As a known separator, for example, a microporous film using a polyolefin-based resin (polyethylene, polypropylene, polybutene, polyvinyl chloride), polyethylene terephthalate, polycycloolefin, polyether sulfone, polyamide, polyimide, polyimide amide, polyaramid, Examples thereof include a microporous film using a resin such as polycycloolefin, nylon, and polytetrafluoroethylene, a woven or non-woven fabric using a polyolefin-based fiber, and an aggregate of particles made of an insulating material. Among these, the thickness of the entire separator can be reduced, thereby increasing the ratio of the electrode mixture layer in the non-aqueous secondary battery and increasing the capacity per volume, A microporous film using a polyolefin resin (polyethylene, polypropylene, polybutene, polyvinyl chloride) is preferred.

[Adhesive layer]
Here, when a separator is provided between the positive electrode and the negative electrode, a known adhesive layer may be provided between the electrode and the separator in order to satisfactorily integrate the electrode (positive electrode, negative electrode) and the separator. it can.
However, the negative electrode active material in the negative electrode mixture layer provided in the nonaqueous secondary battery expands and contracts as the battery is charged and discharged. Therefore, for example, when the negative electrode mixture layer and the separator are firmly bonded via the adhesive layer, the stress due to the expansion and contraction of the negative electrode active material cannot be sufficiently relaxed, and the negative electrode mixture layer It can cause cracks and cracks. Therefore, it is preferable not to provide an adhesive layer between the negative electrode mixture layer and the separator. Moreover, even if an adhesive layer is provided between the negative electrode mixture layer and the separator, it is preferable to use an adhesive layer having a low adhesive force.
Specifically, the adhesive force between the negative electrode and the separator when an uncharged non-aqueous secondary battery is left at a temperature of 60 ° C. for 15 hours is preferably 1.0 N / m or less, and 0.5 N / m or less. More preferably, it is 0.3 N / m or less, more preferably 0.15 N / m or more. This is because, if the adhesive force is 1.0 N / m or less, it is possible to suppress the exfoliation of the negative electrode mixture layer caused by the expansion and contraction of the negative electrode active material during charge / discharge.

<Battery container>
The battery container of the non-aqueous secondary battery manufactured using the manufacturing method of the present invention is not particularly limited, and any container body can be used. Specifically, as the battery container, for example, a packaging material or a case formed using a light metal such as aluminum or steel can be adopted.

<Assembly process>
In the assembly process included in the method for manufacturing a non-aqueous secondary battery of the present invention, a positive electrode, a negative electrode, and an electrolytic solution are accommodated in a battery container to prepare an uncharged non-aqueous secondary battery. The positive electrode and the negative electrode may be accommodated in the battery container in a state where a separator is disposed between the positive electrode and the negative electrode.

  Specifically, in the assembly process, for example, typically, in the normal temperature range, the positive electrode and the negative electrode are overlapped via a separator to obtain a laminate, and then the obtained laminate is required. Depending on the shape of the battery, it is wound or folded into a battery container. Thereafter, an uncharged non-aqueous secondary battery is assembled by injecting an electrolytic solution into the battery container containing the laminate and sealing the battery container. Here, in this specification, “room temperature region” refers to 20 ° C. ± 10 ° C.

  In order to prevent the occurrence of pressure increase and overcharge / discharge in the non-aqueous secondary battery, the non-charged non-aqueous secondary battery includes an overcurrent prevention element such as a fuse or a PTC element as necessary. An expanded metal, a lead plate, or the like may be provided. Moreover, the shape of the non-chargeable non-aqueous secondary battery to be assembled may be any of a coin type, a button type, a sheet type, a cylindrical type, a square shape, a flat type, and the like.

<Heating process>
In the heating step included in the method for producing a non-aqueous secondary battery of the present invention, the temperature of the non-charged non-aqueous secondary battery obtained by the above-described assembly step is raised to a high temperature range of 40 ° C. or higher, whereby an electrode mixture is obtained. The electrolyte solution penetrates well into the layer (particularly the negative electrode mixture layer). In the heating step, the permeation of the electrolyte solution into the electrode mixture layer can be further promoted by holding the non-charged non-aqueous secondary battery heated to a predetermined temperature at the temperature for a predetermined time.

  Here, the heating temperature of the non-charged non-aqueous secondary battery needs to be 40 ° C. or higher, preferably 50 ° C. or higher, more preferably 55 ° C. or higher, preferably 85 ° C. or lower, more preferably 70 ° C. or lower. preferable. If an uncharged non-aqueous secondary battery is heated at 40 ° C. or higher, the electrolyte viscosity in the battery decreases, so that the electrolyte easily enters the electrode mixture layer, and is sufficiently in the electrode mixture layer. It becomes easy to get around. As a result, even when a high-density negative electrode mixture layer is used, it is possible to suppress the formation failure of SEI film and the occurrence of metal precipitation at the time of initial charging described later, and good life characteristics and rate characteristics. A non-aqueous secondary battery having Further, if the non-charged non-aqueous secondary battery is heated at 85 ° C. or less, the non-aqueous secondary battery can be manufactured safely by preventing the electrolyte from igniting during heating.

  Furthermore, the heating and holding (temperature holding) time of the heated non-charged non-aqueous secondary battery is preferably 1 hour or longer, more preferably 5 hours or longer, further preferably 10 hours or longer, and preferably 50 hours or shorter. This is because if the uncharged non-aqueous secondary battery is heated for 1 hour or longer, the electrolyte solution can be sufficiently permeated into the electrode mixture layer. Further, if heating of the non-charged non-aqueous secondary battery is set to 50 hours or less, deterioration of the electrode mixture layer due to long-time heating can be prevented, and reduction in production efficiency of the non-aqueous secondary battery can be suppressed. Because.

  In the method for producing a non-aqueous secondary battery according to the present invention, since the negative electrode mixture layer containing a water-insoluble polymer having a predetermined property and a water-soluble polymer is used, the above heat treatment is performed. In addition, it is possible to suppress the peeling and cracking of the negative electrode mixture layer.

<Initial charging process>
In the initial charging step included in the method for manufacturing the non-aqueous secondary battery of the present invention, the non-charged non-aqueous secondary battery heated by the above-described heating step is charged to a predetermined charging depth, so that In addition, an excellent SEI film is efficiently formed. Here, from the viewpoint of efficiently forming a sufficient SEI film on the negative electrode mixture layer, the charging depth is preferably 5% or more and 80% or less.
In the non-aqueous secondary battery manufacturing method of the present invention, since the heating step described above is performed before the initial charging step, it is possible to suppress the formation failure of the SEI film and the occurrence of metal deposition. A non-aqueous secondary battery having excellent battery characteristics can be obtained.

EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to these Examples. In the following description, “%” and “part” representing amounts are based on mass unless otherwise specified.
In Examples and Comparative Examples, the heating temperature of the non-charged non-aqueous secondary battery, the electrolyte solution swelling degree of the water-insoluble polymer and the water-soluble polymer, the gel amount of the water-insoluble polymer, the tap density of the negative electrode active material, The adhesive strength between the negative electrode and the separator, the state of the negative electrode mixture layer after the initial full charge, and the rate characteristics of the non-aqueous secondary battery were measured, evaluated, or observed using the following methods, respectively.

<Heating temperature>
The heating temperature was set as an arbitrary temperature using a thermostat (model number: PU-2KT, manufactured by Espec Corp.) and then measured as an actual ambient temperature around the non-charged non-aqueous secondary battery. The measurement results are shown in Table 1.

<Electrolytic solution swelling>
The degree of swelling of the electrolytic solution is determined for each of the water-insoluble polymer and the water-soluble polymer by the weight of the water-insoluble polymer or the dry film piece containing the water-soluble polymer and the water-insoluble polymer or water-soluble polymer. It can obtain | require using the weight of the swelling film piece obtained by immersing the dry film piece to contain in electrolyte solution. Specifically, an aqueous dispersion or aqueous solution in which a water-insoluble polymer or a water-soluble polymer is dispersed or dissolved in water is prepared, and the prepared aqueous dispersion or aqueous solution has a humidity of 50% and a temperature of 23 ° C. or more and 25 ° C. It dried in the environment below ℃ and obtained the dry dispersion. Then, the obtained dry dispersion was formed into a film with a thickness of 3 ± 0.3 mm and cut into a diameter of 12 mm to prepare a dry film piece.
The prepared dry film piece was precisely weighed, and the weight of the obtained dry film piece was designated as W0.
Next, the precisely weighed dry film piece was a mixed solvent of LiPF ₆ electrolyte solution (solvent: ethylene carbonate / ethyl methyl carbonate = 3/7 (volume ratio)) having a concentration of 1.0 M, and 2 mass of vinylene carbonate as an additive. % (Including the solvent ratio)) was immersed in 60 g at 60 ° C. for 72 hours, and the electrolytic solution was permeated into the dried film piece. And the film piece swollen by the osmosis | permeation of electrolyte solution, ie, the swelling film piece, was obtained.
Thereafter, the swollen film piece pulled up from the electrolytic solution was lightly wiped, and the weight of the swollen film piece obtained by precise weighing was defined as W1.
And the following formula (I):
Electrolyte swelling degree = (W1 / W0) (I)
Thus, the degree of swelling (times) of the electrolyte was calculated. The measurement results are shown in Table 1.

<Amount of gel>
The gel amount can be determined as the ratio (mass%) of the solid content insoluble in tetrahydrofuran out of the solid content of the water-insoluble polymer with respect to the total solid content of the water-insoluble polymer. Specifically, an aqueous dispersion in which a water-insoluble polymer is dispersed in water is dried for 3 days in an environment of 50% humidity and a temperature of 23 ° C. or more and 25 ° C. or less, and further using a hot air oven, A dried dispersion was obtained by drying in a 120 ° C. environment for 1 hour. The obtained dried dispersion was formed into a film having a thickness of 3 ± 0.3 mm, and cut into a substantially square shape having a side of 3 mm or more and 5 mm or less to prepare a dry film piece.
The prepared dry film piece was precisely weighed, and the weight of the obtained dry film piece was designated as V0.
Next, the dried film piece was immersed and dissolved in 100 g of tetrahydrofuran at 23 ° C. or more and 25 ° C. or less for 24 hours. The residual film piece lifted from tetrahydrofuran was vacuum-dried at 105 ° C. for 3 hours, and then the dried residual film piece was precisely weighed, and the weight of the obtained residual film piece was set to V1.
And the following formula (II):
Gel amount = (V1 / V0) × 100 (II)
Thus, the gel amount (mass%) was calculated. The measurement results are shown in Table 1.

<Tap density>
The tap density of the negative electrode active material was measured using a powder tester (registered trademark) (manufactured by Hosokawa Micron Corporation, PT-D). Specifically, first, the powder of the negative electrode active material filled in the measurement container was ground on the upper surface of the container. Next, a cap attached to the measuring instrument was attached to the measurement container, and a powder of the negative electrode active material was additionally filled up to the upper edge of the attached cap, and tapping was performed by repeatedly dropping from a height of 1.8 cm to 180 times. After the tapping, the cap was removed, and the negative electrode active material powder was ground again on the upper surface of the container. The sample worn after tapping was weighed, and the bulk density in this state was hardened and measured as the bulk density, that is, the tap density (g / cm ³ ). It shows that the density of a negative electrode active material is so high that a tap density is high, and the nonaqueous secondary battery suitable for high-density charging / discharging is obtained. The measurement results are shown in Table 1.

<Adhesive strength between negative electrode and separator>
The adhesive force between the negative electrode and the separator was measured as tensile stress on the negative electrode surface. Specifically, the uncharged non-aqueous secondary battery obtained in the assembly process was subjected to heat treatment at the heating temperature and the heating holding time in each Example and each Comparative Example described in Table 1. Thereafter, the laminate including the negative electrode and the separator immersed in the electrolytic solution is taken out from the uncharged non-aqueous secondary battery subjected to the heat treatment, and cut into a size of 10 mm length × 10 mm width to obtain a test piece. It was. And the electrolyte solution adhering to the surface of the obtained test piece was wiped off, and the adhesive tape was affixed on the negative electrode surface side among the wiped test piece surfaces. At this time, the adhesive tape defined in JIS Z1522 was used. Then, the stress when the one end of the test piece was pulled vertically upward at a pulling speed of 50 mm / min was measured as an adhesive force (the adhesive tape was fixed to a horizontal test stand).
The measurement results are shown in Table 1. Even when the adhesive layer is not provided between the negative electrode and the separator, the stress due to the liquid film of the electrolyte acts at the negative electrode mixture layer interface, and therefore the adhesive force is usually 0 regardless of the presence or absence of the adhesive layer. Shows a measured value of 1 N / m or more.

<State of negative electrode mixture layer after initial full charge>
Five non-aqueous secondary batteries manufactured by the methods described in each Example and each Comparative Example were disassembled in a dry room and visually observed for cracking and peeling of the negative electrode mixture layer. Here, in Comparative Example 4, a non-aqueous secondary battery after completion of heating was used. The evaluation criteria were as follows. The measurement results are shown in Table 1.
A: The number of batteries in which defects (cracking or peeling) of the negative electrode mixture layer are found is 1 or less B: The number of batteries in which defects (breaking or peeling) of the negative electrode mixture layer are seen is two C: Negative electrode mixture The number of batteries in which layer defects (cracking or peeling) are observed is three. D: The number of batteries in which defects (breaking or peeling) are observed in the negative electrode composite material layer is four or more.

<Rate characteristics of non-aqueous secondary batteries>
After confirming the initial capacity of the non-aqueous secondary battery produced by the method described in each example and each comparative example, the non-aqueous secondary battery was constant current and constant voltage up to 4.2 V at 0.2 C in a 25 ° C. environment. The battery was fully charged by the method (cut-off condition: 0.02 C). Thereafter, the non-aqueous secondary battery was discharged at a constant current up to 3.0 V at 0.2 C in a 25 ° C. environment, and the discharge capacity C1 at that time was measured. The non-aqueous secondary battery is fully charged again by the constant current / constant voltage method (cut-off condition: 0.02C) of 4.2V in a 25 ° C environment, and then reaches 3.0V at 1C in a 25 ° C environment. A constant current was discharged, and the discharge capacity C2 at that time was measured. The rate characteristic C ₂ / C ₁ of the non-aqueous secondary battery is expressed by the following formula (III):
C ₂ / C ₁ = (C2 / C1) × 100 (III)
The ratio was calculated as the ratio (%) of C2 to C1. The evaluation criteria were as follows. The larger the C ₂ / C ₁ value shows that the superior rate characteristics of a nonaqueous secondary battery produced. The measurement results are shown in Table 1.
A: C ₂ / C ₁ is 85% or more B: C ₂ / C ₁ is less than 85% 75% or more C: C ₂ / C ₁ is less than 75% 65% or more D: C ₂ / C ₁ is less than 65%

Example 1
<Preparation of water-insoluble polymer>
63 parts of styrene as an aromatic vinyl monomer, 33 parts of 1,3-butadiene as an aliphatic conjugated diene monomer, 4 parts of itaconic acid as an acidic group-containing monomer, t-dodecyl as a chain transfer agent 0.3 parts of mercaptan and 0.35 parts of sodium lauryl sulfate as an emulsifier were put in a container A to obtain a mixture. Polymerization was started by adding 1 part of potassium persulfate as a polymerization initiator to the pressure vessel B at the same time as adding the obtained mixture from the vessel A to the pressure vessel B. The polymerization reaction temperature was maintained at 75 ° C.
When the polymerization conversion rate reached 97%, the mixture was cooled and the reaction was stopped to obtain a mixture containing a water-insoluble polymer. A sodium hydroxide aqueous solution having a concentration of 5% was added to the resulting mixture containing the water-insoluble polymer to adjust the pH to 8. Thereafter, unreacted monomers were removed by heating under reduced pressure. Thereafter, the mixture was cooled to obtain an aqueous dispersion (solid content concentration: 40%) containing a water-insoluble polymer.

<Preparation of negative electrode active material>
Spherical graphite particles having an average particle diameter of 100 μm are spheroidized using a hybridization system (manufactured by Nara Machinery Co., Ltd., model number: NHS-3, rotation speed (rotor peripheral speed): 65 m / sec, rotation residence time: 15 minutes). By processing, spherical graphite particles having a volume average particle diameter (50% diameter) of 15 μm and a tap density of 1.02 g / cm ³ were obtained.
Thereafter, 30 parts of tar pitch as a low-crystalline film-forming carbon material was added to 100 parts of the obtained spherical graphite particles, and mixed for 30 minutes in a 200 ° C. environment using a Henschel mixer. The obtained mixture was pre-fired at 1000 ° C. in a nitrogen atmosphere, and further fired at 1500 ° C. in a nitrogen atmosphere and pulverized, whereby the core of spherical graphite particles was amorphous-coated with tar pitch, A negative electrode active material was obtained. The obtained negative electrode active material had a volume average particle diameter (50% diameter) of 15 μm and a tap density of 1.04 g / cm ³ .

<Preparation of slurry composition for negative electrode>
In a planetary mixer with a disper, 100 parts of the carbon-based negative electrode active material obtained as described above, and an acrylamide polymer (acrylic acid unit / acrylamide unit = 50% / 50%) as a water-soluble polymer One part in terms of solid content was added to obtain a mixture. Ion exchange water was added to the resulting mixture to adjust the solid content concentration to 60%, and then the mixture was mixed in a 25 ° C. environment for 60 minutes. Next, after adjusting solid content concentration to 48% using ion-exchange water, it further mixed for 15 minutes in 25 degreeC environment, and obtained the liquid mixture of a negative electrode active material and a water-soluble polymer.
To the mixed liquid of the obtained negative electrode active material and the water-soluble polymer, an aqueous dispersion containing the water-insoluble polymer prepared by the above-described method (2 parts in terms of solid content of the water-insoluble polymer) is added, The final solid content concentration was adjusted to 50% using ion-exchanged water, and further mixed for 10 minutes, and then defoamed under reduced pressure to obtain a slurry composition for negative electrode.

<Preparation of negative electrode for non-aqueous secondary battery>
Using a comma coater (manufactured by Sunk Metal Co., Ltd.), the coating amount of the negative electrode slurry composition obtained as described above was 9 mg / cm ² on one surface of a copper foil (thickness 15 μm) as a current collector. It was applied so as to be 10 mg / cm ² or less. The copper foil coated with the slurry composition for the negative electrode is dried by transporting it in a 60 ° C. oven for 2 minutes (speed: 0.5 m / min), and further heat-treated in a 120 ° C. oven for 2 minutes. Thus, a negative electrode raw material was obtained.
The obtained negative electrode raw material is pressed with a load of 11 to 14 tons using a roll press machine, whereby a negative electrode mixture layer having a density of 1.75 g / cm ³ is provided on the current collector. A negative electrode for an aqueous secondary battery was obtained.

<Preparation of positive electrode for non-aqueous secondary battery>
In a planetary mixer, 100 parts of LiCoO ₂ as a positive electrode active material, ₂ parts of acetylene black (manufactured by Denki Kagaku Kogyo Co., Ltd., product number: HS-100) as a conductive material, and polyvinylidene fluoride (Kureha Chemical) as a binder A slurry composition for a positive electrode was prepared by adding and mixing 2 parts of a product, product number: KF-1100) and 2-methylpyrrhodone in an amount such that the total solid content concentration was 67%.
The obtained positive electrode slurry composition was applied onto one surface of an aluminum foil (thickness 20 μm) as a current collector by the comma coater. The aluminum foil coated with the positive electrode slurry composition is dried by conveying it in an oven at 60 ° C. over 2 minutes (speed: 0.5 m / min), and further heat-treated in an oven at 120 ° C. for 2 minutes. Did. The same coating and drying operation was performed on the other surface of the current collector to obtain a positive electrode raw material.
By pressing the obtained positive electrode fabric using the roll press machine so that the density of the positive electrode mixture layer is 3.40 mg / cm ³ or more and 3.50 g / cm ³ or less, a non-aqueous secondary material is obtained. A positive electrode for a battery was obtained.

<Manufacture of non-aqueous secondary batteries>
On one side of a single-layer polypropylene separator (length 500 mm × width 65 mm × thickness 25 μm, porosity 55%, manufactured by dry method), an adhesive layer composition (manufactured by ZEON Corporation, product name: BM-2500M) An adhesive layer having a thickness of 1 μm per layer was formed on the separator by applying by a gravure coating method (number of lines: 300) and drying in a 50 ° C. environment for 1 minute. Next, the separator on which the adhesive layer was formed was cut out into a length of 50 mm × a width of 40 mm, the positive electrode prepared as described above was cut out into a length of 45 mm × width of 35 mm, and the negative electrode prepared as described above was cut into a length of 47 mm × width of 37 mm. Cut out. And the cut-out positive electrode, separator, and negative electrode were piled up as follows, and the non-aqueous secondary battery was manufactured.
Specifically, separators were disposed on both sides of the positive electrode provided with the positive electrode mixture layer on both sides, and the positive electrode was sandwiched between the separators. The positive electrode mixture layer was brought into contact with the surface on which the separator adhesive layer was applied. Then, the negative electrode was stacked on the surface of the separator that was not in contact with the positive electrode (the surface on which the adhesive layer was not provided) to obtain a laminate. And the obtained laminated body was put into the aluminum packaging material exterior as a battery container, and the laminated battery was obtained.
Then, in the laminated battery, a LiPF ₆ solution having a concentration of 1.0 M as an electrolytic solution (solvent: ethylene carbonate (EC) / ethyl methyl carbonate (EMC) = 3/7 (volume ratio) mixed solvent, additive) As vinylene carbonate (containing 2% by mass). Further, the laminated battery filled with the electrolytic solution was heat sealed at a temperature of 150 ° C., and the opening of the aluminum packaging exterior was hermetically closed, followed by pressing at a pressure of 10 MPa for 5 seconds in an environment of 25 ° C. And an uncharged non-aqueous secondary battery were obtained (assembly process). And the adhesive force of a negative electrode and a separator was evaluated using the obtained non-charging non-aqueous secondary battery.
Moreover, after heating the obtained non-chargeable non-aqueous secondary battery at a temperature of 60 ° C. for 15 hours (heating process), the constant current / constant voltage method (cut-off method) up to 4.2 V at 0.2 C in a 25 ° C. environment. Under the condition: 0.02C), the battery was charged to a charging depth of 20% (initial charging step) to manufacture a lithium ion secondary battery as a non-aqueous secondary battery. Then, the state of the negative electrode mixture layer after the initial full charge and the rate characteristics of the non-aqueous secondary battery were evaluated using the manufactured lithium ion secondary battery.

(Example 2)
A water-insoluble polymer, a negative electrode active material, a slurry composition, a negative electrode, a positive electrode, and a non-aqueous system were produced in the same manner as in Example 1 except that the heating temperature in the heating step was changed to 50 ° C. during the production of the non-aqueous secondary battery. A secondary battery was manufactured. Then, evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

(Example 3)
In preparing the water-insoluble polymer, the amount of styrene is 29.5 parts, the amount of 1.3-butadiene is 47.5 parts, the amount of itaconic acid is 3 parts, and the amount of t-dodecyl mercaptan is 1 3 parts, and 20 parts of acrylonitrile as another monomer was added to the mixture. Moreover, at the time of preparation of the slurry composition, the kind of the water-soluble polymer was changed to a sodium salt of carboxymethyl cellulose (manufactured by Daicel Finechem, product name: CMC Daicel 2200). Furthermore, when manufacturing the non-aqueous secondary battery, in the assembly process, the adhesive layer of the separator is in contact with the negative electrode mixture layer, and the side of the separator that is not in contact with the negative electrode (the side where the adhesive layer is not provided) After the positive electrode is stacked on top of the other and the opening of the aluminum packaging material exterior is hermetically closed by heat sealing, the negative electrode and the separator are pressure-bonded by pressing at a pressure of 10 MPa for 5 seconds in a 25 ° C. environment. Thus, an uncharged non-aqueous secondary battery was obtained. Except for the above, a water-insoluble polymer, a negative electrode active material, a slurry composition, a negative electrode, a positive electrode, and a nonaqueous secondary battery were produced in the same manner as Example 1. Then, evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

Example 4
When preparing the negative electrode active material, the tap density of the amorphous coated negative electrode active material was adjusted by adjusting the conditions of the hybridization system to a rotation speed (rotor peripheral speed): 40 m / second and a rotation residence time: 10 minutes. change to 0.86 g / cm ^3, further, during the preparation of the slurry composition, the kind of the water-soluble polymer sodium salt of carboxymethyl cellulose (Daicel Finechem Corporation, product name: CMC Daicel 2200) was changed to an In the same manner as in Example 1, a water-insoluble polymer, a negative electrode active material, a slurry composition, a negative electrode, a positive electrode, and a non-aqueous secondary battery were produced. Then, evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

(Example 5)
At the time of preparing the slurry composition, the type of the water-soluble polymer was changed to a sodium salt of carboxymethyl cellulose (manufactured by Daicel Finechem, product name: CMC Daicel 2200), and the amount of the water-insoluble polymer was changed to 1 part by mass. Except for the above, a water-insoluble polymer, a negative electrode active material, a slurry composition, a negative electrode, a positive electrode, and a nonaqueous secondary battery were produced in the same manner as in Example 1. Then, evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

(Example 6)
During the preparation of the slurry composition, the type of the water-soluble polymer was changed to a sodium salt of carboxymethyl cellulose (manufactured by Daicel Finechem, product name: CMC Daicel 2200). Furthermore, when manufacturing the non-aqueous secondary battery, in the assembly process, the adhesive layer of the separator is in contact with the negative electrode mixture layer, and the side of the separator that is not in contact with the negative electrode (the side where the adhesive layer is not provided) After the positive electrode is stacked on top of the other, and the opening of the aluminum packaging material is hermetically sealed by heat sealing, the negative electrode and the separator are pressure-bonded by pressing at a pressure of 10 MPa for 5 seconds in a 50 ° C. environment. Thus, an uncharged non-aqueous secondary battery was obtained. Except for the above, a water-insoluble polymer, a negative electrode active material, a slurry composition, a negative electrode, a positive electrode, and a nonaqueous secondary battery were produced in the same manner as Example 1. Then, evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Example 1)
Except that the amount of t-dodecyl mercaptan was changed to 3.0 parts during the preparation of the water-insoluble polymer, the same procedure as in Example 3 was followed, except that the water-insoluble polymer, the negative electrode active material, the slurry composition, the negative electrode, A positive electrode and a non-aqueous secondary battery were manufactured. Then, evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Example 2)
During the preparation of the slurry composition, the type of the water-soluble polymer was changed to a sodium salt of carboxymethyl cellulose (manufactured by Daicel Finechem Co., Ltd., product name: CMC Daicel 2200), and further, the heating in the heating step was performed during the production of the non-aqueous secondary battery. A water-insoluble polymer, a negative electrode active material, a slurry composition, a negative electrode, a positive electrode, and a nonaqueous secondary battery were produced in the same manner as in Example 1 except that the temperature was changed to 25 ° C. Then, evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Example 3)
Copolymer of ethyl acrylate unit (EA) / butyl acrylate unit (BA) / methacrylamide unit (MAA) = 40/30/30 (mass ratio) at the time of preparing the slurry composition Changed to Furthermore, when manufacturing the non-aqueous secondary battery, in the assembly process, the adhesive layer of the separator is in contact with the negative electrode mixture layer, and the side of the separator that is not in contact with the negative electrode (the side where the adhesive layer is not provided) After the positive electrode is stacked on top of the other, and the opening of the aluminum packaging exterior is hermetically sealed by heat sealing, the negative electrode and the separator are pressure-bonded by pressing at a pressure of 10 MPa for 5 seconds in a 30 ° C. environment. Thus, an uncharged non-aqueous secondary battery was obtained. Except for the above, a water-insoluble polymer, a negative electrode active material, a slurry composition, a negative electrode, a positive electrode, and a nonaqueous secondary battery were produced in the same manner as Example 1. Then, evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Example 4)
During the preparation of the slurry composition, the type of the water-soluble polymer was changed to a sodium salt of carboxymethyl cellulose (manufactured by Daicel Finechem, product name: CMC Daicel 2200). Furthermore, when the non-aqueous secondary battery is manufactured, the non-charged non-aqueous secondary battery obtained in the assembly process is charged to a charging depth of 20% at 0.1 C without performing a heating process, and then in a 60 ° C. environment. For 15 hours, and further charged at 0.2 C to 4.2 V by a constant current constant voltage charging method (cut-off condition: 0.02 C) to produce a non-aqueous secondary battery. Except for the above, a water-insoluble polymer, a negative electrode active material, a slurry composition, a negative electrode, a positive electrode, and a nonaqueous secondary battery were produced in the same manner as Example 1. Then, evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

ＴＤＭ：ｔ−ドデシルメルカプタン
ＴＨＦ：テトラヒドロフラン
ＡＡ／Ａａｍ：アクリル酸／アクリルアミド共重合体
ＣＭＣ：カルボキシメチルセルロースのナトリウム塩
ＥＡ／ＢＡ／ＭＡＡ：アクリル酸エチル／アクリル酸ブチル／メタクリルアミド共重合体

TDM: t-dodecyl mercaptan THF: tetrahydrofuran AA / Aam: acrylic acid / acrylamide copolymer CMC: sodium salt of carboxymethyl cellulose EA / BA / MAA: ethyl acrylate / butyl acrylate / methacrylamide copolymer

From Table 1, in Examples 1-6 which performed the heating process before the initial charge process, compared with the comparative example 4 which performed the heat treatment after the initial charge, the non-aqueous secondary with excellent rate characteristics immediately after the initial charge / discharge. It can be seen that a battery is obtained.
However, even if the heating step is performed before the initial charging step, in Comparative Example 2 in which the heating temperature is 25 ° C., the rate immediately after the initial charge / discharge is compared with Examples 1 to 6 in which the heating temperature is 40 ° C. or higher. It turns out that a characteristic deteriorates remarkably.
Further, in Comparative Example 1 using a water-insoluble polymer having an electrolyte solution swelling degree of more than 4.0 times and a gel amount of less than 80% by mass, the electrolyte solution swelling degree of more than 1.0 times is 4.0. In comparison with Examples 1 to 6 using a water-insoluble polymer having a gel amount of 80% by mass or more and 95% by mass or less, the loss of the negative electrode mixture layer after the initial charge is remarkably advanced. It can be seen that the rate characteristics immediately after the initial charge / discharge are also significantly deteriorated.
Further, in Comparative Example 3 using a water-soluble polymer having an electrolyte solution swelling degree exceeding 2.0 times, an example using a water-soluble polymer having an electrolyte solution swelling degree exceeding 1.0 times and 2.0 times or less Compared with 1-6, it turns out that the defect | deletion of the negative mix layer after initial charge progresses remarkably, and the rate characteristic immediately after initial charge / discharge is also getting worse remarkably.
In Examples 1 to 6 using a negative electrode mixture layer having a density of 1.70 g / cm ³ or more, the negative electrode mixture layer after initial charge has low defects and a good rate immediately after initial charge / discharge. Thus, it can be seen that the manufacturing method of the present invention is suitable for manufacturing a non-aqueous secondary battery that maintains high battery performance even when a high-density electrode is used.

  ADVANTAGE OF THE INVENTION According to this invention, the method of manufacturing efficiently the non-aqueous secondary battery which formed the SEI membrane | film | coat on the negative mix layer can be provided, suppressing the fall of battery performance.

Claims (5)

An assembly process for assembling an uncharged non-aqueous secondary battery by containing a positive electrode, a negative electrode, and an electrolyte in a battery container;
A heating step of heating the uncharged non-aqueous secondary battery to 40 ° C. or higher;
An initial charging step of charging the uncharged non-aqueous secondary battery after the heating step;
Including
The negative electrode includes a negative electrode mixture layer containing a negative electrode active material, a water-insoluble polymer, and a water-soluble polymer,
The water-insoluble polymer has an electrolyte swelling degree of more than 1.0 times and 4.0 times or less, and a gel amount of 80% by mass or more and 95% by mass or less,
The water-soluble polymer has an electrolyte swelling degree of more than 1.0 times and not more than 2.0 times.
A method for producing a non-aqueous secondary battery. The method for producing a non-aqueous secondary battery according to claim 1, wherein the negative electrode active material has a tap density of 0.8 g / cm ³ or more and 1.2 g / cm ³ or less. The manufacturing method of the non-aqueous secondary battery according to claim 1 or 2, wherein the density of the negative electrode mixture layer is 1.60 g / cm ³ or more.   The negative electrode mixture layer contains the water-insoluble polymer in a proportion of 0.5 parts by mass or more and 4 parts by mass or less per 100 parts by mass of the negative electrode active material, and 0.5 parts by mass of the water-soluble polymer. The manufacturing method of the non-aqueous secondary battery of any one of Claim 1 to 3 contained in the ratio of 3 mass parts or less above. The uncharged non-aqueous secondary battery further includes a separator between the negative electrode and the positive electrode,
5. The adhesive force between the negative electrode and the separator when the uncharged non-aqueous secondary battery is left at a temperature of 60 ° C. for 15 hours is 1.0 N / m or less. Of manufacturing a non-aqueous secondary battery.