JP2017103034A - Method for forming functional layer for non-aqueous secondary battery, and method for manufacturing non-aqueous secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for forming a functional layer for a non-aqueous secondary battery, capable of forming the functional layer for a non-aqueous secondary battery having excellent peel strength.SOLUTION: A method for forming a functional layer for a non-aqueous secondary battery includes the steps of: giving onto a base material a composition for the functional layer including a non-conductive particle and a binding agent having a volume average particle diameter D50 which is smaller than that of the non-conductive particle; and applying the surface activation processing to the composition for the functional layer given onto the base material.SELECTED DRAWING: None

Description

  The present invention relates to a method for forming a functional layer for a non-aqueous secondary battery and a method for producing a non-aqueous secondary battery.

  Non-aqueous secondary batteries such as lithium ion secondary batteries (hereinafter sometimes simply referred to as “secondary batteries”) have the characteristics of being small and light, having high energy density, and capable of repeated charge and discharge. Yes, it is used for a wide range of purposes. The secondary battery generally includes a battery member such as a positive electrode, a negative electrode, and a separator that separates the positive electrode and the negative electrode and prevents a short circuit between the positive electrode and the negative electrode.

  Here, in recent years, in secondary batteries, battery members having a functional layer such as an adhesive layer for the purpose of improving adhesion between battery members have been used. Specifically, an electrode in which a functional layer is further formed on an electrode base material provided with an electrode mixture layer on a current collector, or a separator in which a functional layer is formed on a separator base material is a battery. It is used as a member (see, for example, Patent Document 1).

  This functional layer is usually a slurry-like composition for a non-aqueous secondary battery functional layer (hereinafter referred to as “functional layer composition”) containing a binder component and a dispersion medium such as water. Is provided on an appropriate substrate such as an electrode substrate or a separator substrate and dried (see, for example, Patent Document 1).

JP 2013-105681 A

  However, the conventional functional layer has a demand to further improve the battery characteristics such as the high-temperature cycle characteristics of the non-aqueous secondary battery by further improving the adhesion (peel strength) between the battery members. There was room for.

Then, an object of this invention is to provide the formation method of the functional layer for non-aqueous secondary batteries which can form the functional layer for non-aqueous secondary batteries which has the outstanding peel strength.
Moreover, an object of this invention is to provide the manufacturing method of a non-aqueous secondary battery which can manufacture the non-aqueous secondary battery which is excellent in battery characteristics, such as a high temperature cycling characteristic.

  The present inventor has intensively studied for the purpose of solving the above problems. And this inventor intends optimization of the component contained in a functional layer, and by giving a predetermined process to the composition for functional layers provided by apply | coating etc. on a base material, the non-aqueous secondary obtained The present inventors have found that the peel strength of the functional layer for batteries can be improved.

That is, the present invention aims to advantageously solve the above-described problems, and the method for forming a functional layer for a non-aqueous secondary battery according to the present invention comprises a non-conductive particle and a non-conductive particle on a substrate. A step of applying a functional layer composition containing a binder having a volume average particle size D50 smaller than the volume average particle size D50 of the conductive particles, and surface activity to the functional layer composition applied on the substrate And a step of performing a crystallization process. Thus, if the composition for functional layers containing a nonelectroconductive particle and a binder is provided on a base material, and surface activation treatment is applied thereto, the function for a non-aqueous secondary battery having excellent peel strength A layer can be formed.
In the present invention, the “volume average particle diameter D50” of the non-conductive particles and the binder can be measured using the measuring method described in the examples of the present specification.

  Here, in the method for forming a functional layer for a non-aqueous secondary battery according to the present invention, the surface activation treatment is preferably a corona discharge treatment or a plasma discharge treatment. If corona discharge treatment or plasma discharge treatment is applied to the functional layer composition on the substrate as the surface activation treatment, the functional layer for the non-aqueous secondary battery is applied to the surface of the functional layer composition applied on the substrate. The battery characteristics such as the high-temperature cycle characteristics of the non-aqueous secondary battery using the functional layer for non-aqueous secondary battery can be further improved.

In the method for forming a functional layer for a non-aqueous secondary battery of the present invention, the surface activation treatment is a corona discharge treatment, and a discharge amount in the corona discharge treatment is 10 W · min / m ² or more and 200 W · min / It is preferably m ² or less. If the discharge amount in the corona discharge treatment is within the above range, the peel strength of the non-aqueous secondary battery functional layer can be effectively increased, and the non-aqueous secondary battery functional layer can be used. The high-temperature cycle characteristics of the secondary battery can be effectively improved, and the occurrence of problems such as blocking, short-circuiting and hole opening due to overheating of the substrate can be sufficiently suppressed.

In the method for forming a functional layer for a non-aqueous secondary battery of the present invention, the contact angle of the functional layer with respect to water is preferably 50 ° or more and 80 ° or less. If the contact angle with respect to the water of a functional layer is in the above-mentioned range, even when a battery member provided with the functional layer is wound, blocking is unlikely to occur, and the peel strength can be further increased.
In the present invention, the “contact angle of the functional layer with respect to water” can be measured using the measurement method described in the examples of the present specification.

  Moreover, this invention aims at solving the said subject advantageously, and the manufacturing method of the non-aqueous secondary battery of this invention is a non-aqueous secondary battery provided with a positive electrode, a negative electrode, a separator, and electrolyte solution. A functional layer is formed by the method according to any one of claims 1 to 4 on a substrate selected from a separator substrate and an electrode substrate, and the positive electrode, the negative electrode, and the negative electrode It includes a step of producing at least one of the separators. Thus, if at least one of the positive electrode, the negative electrode, and the separator is formed by forming the functional layer on the base material by the method for forming the functional layer for a non-aqueous secondary battery of the present invention, the functional layer is excellent. A non-aqueous secondary battery having excellent battery characteristics such as high-temperature cycle characteristics can be produced by exhibiting peel strength.

  Here, the method for producing a non-aqueous secondary battery of the present invention can be preferably applied to the production of a wound or stacked non-aqueous secondary battery. If at least one of the positive electrode, the negative electrode, and the separator is formed by forming a functional layer on the base material by the method for forming a functional layer for a non-aqueous secondary battery of the present invention, battery members such as an electrode and a separator are It is possible to manufacture a wound or stacked non-aqueous secondary battery that is firmly bonded and has excellent battery characteristics such as high-temperature cycle characteristics.

ADVANTAGE OF THE INVENTION According to this invention, the formation method of the functional layer for non-aqueous secondary batteries which can form the functional layer for non-aqueous secondary batteries which has the outstanding peel strength can be provided.
Moreover, according to this invention, the manufacturing method of the non-aqueous secondary battery which can manufacture the non-aqueous secondary battery excellent in battery characteristics, such as a high temperature cycling characteristic, can be provided.

Hereinafter, embodiments of the present invention will be described in detail.
Here, the method for forming the functional layer for a non-aqueous secondary battery of the present invention can be carried out, for example, when a non-aqueous secondary battery is manufactured by the method for manufacturing a non-aqueous secondary battery of the present invention.
The functional layer may be, for example, a porous film layer for improving the heat resistance and strength of the secondary battery member such as a separator or an electrode, or an adhesive layer for bonding the secondary battery members to each other. It may be a layer that exhibits both functions of the porous membrane layer and the adhesive layer.

(Method for forming functional layer for non-aqueous secondary battery)
The method for forming a functional layer for a non-aqueous secondary battery according to the present invention includes, at least, a step of applying a composition for a functional layer containing non-conductive particles and a binder on a substrate (composition applying step), Applying a surface activation treatment to the functional layer composition applied onto the substrate (surface activation step), and optionally after the composition application step and before the surface activation step, The process (drying process) which dries the composition for functional layers provided on the base material is included. Moreover, the formation method of the functional layer for non-aqueous secondary batteries of this invention may include arbitrary processes other than the process mentioned above. And according to the formation method of the functional layer for non-aqueous secondary batteries of this invention, the functional layer which has the outstanding peel strength can be formed on a base material.

<Composition application process>
Specifically, the composition applying step is a step of applying a functional layer composition containing non-conductive particles and a binder in a layered manner on a substrate. Here, the composition for functional layers used in the composition application step includes non-conductive particles and a binder, and optionally includes other components. The functional layer composition may be a slurry-like composition containing water or the like as a dispersion medium, or may be a solid (powder-like) composition not containing a dispersion medium such as water. .
In the present invention, the functional layer composition applied in layers in the composition application step is not a functional layer. A functional layer is obtained by subjecting the composition for a functional layer applied in a layer form to a surface activation treatment described later.

-Base material-
The base material to which the functional layer composition is applied is not particularly limited. For example, when the functional layer is used as a member constituting a part of the separator, a separator base material can be used as the base material. Moreover, when using a functional layer as a member which comprises a part of electrode, the electrode base material formed by forming an electrode compound-material layer on a collector can be used as a base material. Moreover, there is no restriction | limiting in particular in the usage of the functional layer formed on the base material, For example, a functional layer may be formed on a separator base material etc. and it may use as it is as battery members, such as a separator, The functional layer may be formed on the substrate and used as an electrode, or the functional layer formed on the release substrate may be once peeled off from the substrate and attached to another substrate to be used as a battery member. .
However, from the viewpoint of omitting the step of peeling the release substrate from the functional layer and increasing the production efficiency of the battery member, it is preferable to use a separator substrate or an electrode substrate as the substrate. The functional layer provided on the separator base or electrode base has a function as a protective layer for enhancing the heat resistance and strength of the separator or electrode and a function as an adhesive layer for firmly bonding the separator and the electrode. It can be suitably used as a single layer to be developed simultaneously.

[Separator substrate]
As a separator base material which provides the composition for functional layers, what is described in Unexamined-Japanese-Patent No. 2012-204303 can be used, for example, without being specifically limited. Among these, the film thickness of the entire separator can be reduced, thereby increasing the ratio of the electrode active material in the secondary battery and increasing the capacity per volume. A microporous film made of a resin such as polyethylene, polypropylene, polybutene, or polyvinyl chloride is preferable.
In addition, the separator base material may contain the arbitrary layers which can exhibit the intended function other than the layer of the composition for functional layers provided in the part.

[Electrode substrate]
Although it does not specifically limit as an electrode base material (a positive electrode base material and a negative electrode base material) which provides the composition for functional layers, The electrode base material in which the electrode compound-material layer was formed on the electrical power collector is mentioned. In this case, it is preferable to apply the functional layer composition to the surface of the electrode mixture layer of the electrode substrate.
Here, the current collector, the components in the electrode mixture layer (for example, the electrode active material (positive electrode active material, negative electrode active material) and the electrode mixture layer binder (positive electrode mixture layer binder, negative electrode composite) The material layer binder) and the like, and the method for forming the electrode mixture layer on the current collector may be known ones, for example, those described in JP2013-145663A be able to.
In addition, the electrode base material may contain the arbitrary layers which have an expected function other than the layer of the composition for functional layers provided in a part.

[Release substrate]
It does not specifically limit as a mold release base material which provides the composition for functional layers, A known mold release base material can be used.

-Non-conductive particles-
The non-conductive particles contained in the functional layer composition usually have a function as an adhesive that firmly bonds secondary battery members, for example, a separator and an electrode. The “non-conductive particles” do not include a binder described later.
Non-conductive particles are not particularly limited, and may include known non-conductive particles used in non-aqueous secondary batteries. Specifically, both inorganic particles and organic particles can be used as the non-conductive particles. As inorganic particles, aluminum oxide (alumina), hydrated aluminum oxide (boehmite), silicon oxide, magnesium oxide (magnesia), calcium oxide, titanium oxide (titania), BaTiO ₃ , ZrO, alumina-silica composite oxide, etc. Oxide particles; nitride particles such as aluminum nitride and boron nitride; covalently bonded crystal particles such as silicon and diamond; sparingly soluble ionic crystal particles such as barium sulfate, calcium fluoride and barium fluoride; talc and montmorillonite Clay fine particles; and the like. In addition, these particles may be subjected to element substitution, surface treatment, solid solution, and the like as necessary. On the other hand, the organic particles are not particularly limited as long as they are non-conductive, and known non-conductive organic particles used for the functional layer of the non-aqueous secondary battery can be used. In addition, the nonelectroconductive particle mentioned above may be used individually by 1 type, and may be used in combination of 2 or more types. Moreover, you may use together an organic particle and an inorganic particle as a nonelectroconductive particle.
Among these, organic particles are preferable as the non-conductive particles. By using organic particles as non-conductive particles, the functional layer can more firmly bond the secondary battery members to each other.

Here, the organic particles can be prepared by polymerizing or copolymerizing an arbitrary monomer. Examples of the monomer used to prepare the organic particles include vinyl chloride monomers such as vinyl chloride and vinylidene chloride; vinyl acetate monomers such as vinyl acetate; styrene, α-methylstyrene, Aromatic vinyl monomers such as styrenesulfonic acid, butoxystyrene and vinylnaphthalene; vinylamine monomers such as vinylamine; vinylamide monomers such as N-vinylformamide and N-vinylacetamide; single monomers having a carboxylic acid group Acid group-containing monomers such as monomers, monomers having a sulfonic acid group, monomers having a phosphoric acid group, monomers having a hydroxyl group; (meth) acrylic acid derivatives such as 2-hydroxyethyl methacrylate ; (Meth) acrylates such as methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, 2-ethylhexyl acrylate; Rylic acid ester monomers; (meth) acrylamide monomers such as acrylamide and methacrylamide; (meth) acrylonitrile monomers such as acrylonitrile and methacrylonitrile; 2- (perfluorohexyl) ethyl methacrylate, 2- (per Fluorine-containing (meth) acrylate monomers such as fluorobutyl) ethyl acrylate; maleimide; maleimide derivatives such as phenylmaleimide; diene monomers such as 1,3-butadiene and isoprene; Moreover, these may be used individually by 1 type and may be used combining two or more types by arbitrary ratios.
In the present specification, “(meth) acryl” means acryl and / or methacryl, and “(meth) acrylo” means acrylo and / or methacrylo.

Among the above monomers, it is preferable to use a (meth) acrylic acid ester monomer or a (meth) acrylonitrile monomer as a monomer used for the preparation of the organic particles. It is more preferable to use a monomer. That is, the polymer as the organic particles preferably includes a (meth) acrylic acid ester monomer unit or a (meth) acrylonitrile monomer unit, and more preferably includes a (meth) acrylic acid ester monomer unit. Preferably, it contains a monomer unit derived from methyl methacrylate. Thereby, the ion diffusibility of the functional layer using organic particles can be further enhanced.
The phrase “including a monomer unit” means “a monomer-derived structural unit is contained in a polymer obtained using the monomer”.

  In addition, the polymer as the organic particles can include an acid group-containing monomer unit. Here, as the acid group-containing monomer, a monomer having an acid group, for example, a monomer having a carboxylic acid group, a monomer having a sulfonic acid group, a monomer having a phosphoric acid group, and And monomers having a hydroxyl group.

Examples of the monomer having a carboxylic acid group include monocarboxylic acid and dicarboxylic acid. Examples of the monocarboxylic acid include acrylic acid, methacrylic acid, and crotonic acid. Examples of the dicarboxylic acid include maleic acid, fumaric acid, itaconic acid and the like.
Examples of the monomer having a sulfonic acid group include vinyl sulfonic acid, methyl vinyl sulfonic acid, (meth) allyl sulfonic acid, (meth) acrylic acid-2-ethyl sulfonate, 2-acrylamido-2-methyl. Examples thereof include propanesulfonic acid and 3-allyloxy-2-hydroxypropanesulfonic acid. In the present specification, “(meth) allyl” means allyl and / or methallyl.
Furthermore, examples of the monomer having a phosphate group include phosphoric acid-2- (meth) acryloyloxyethyl phosphate, methyl-2- (meth) acryloyloxyethyl phosphate, and ethyl phosphate- (meth) acryloyloxyethyl phosphate. Etc. In the present specification, “(meth) acryloyl” means acryloyl and / or methacryloyl.
Examples of the monomer having a hydroxyl group include 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, and 2-hydroxypropyl methacrylate.

Among these, as the acid group-containing monomer, a monomer having a carboxylic acid group is preferable, among which monocarboxylic acid is preferable, and (meth) acrylic acid is more preferable.
Moreover, an acid group containing monomer may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

  The polymer as the organic particles preferably contains a crosslinkable monomer unit in addition to the monomer unit. A crosslinkable monomer is a monomer that can form a crosslinked structure during or after polymerization by heating or irradiation with energy rays.

  As a crosslinkable monomer, the polyfunctional monomer which has a 2 or more polymerization reactive group in the said monomer is mentioned, for example. Examples of such a polyfunctional monomer include divinyl compounds such as divinylbenzene; di (ethylene glycol dimethacrylate), ethylene glycol dimethacrylate (ethylene dimethacrylate), diethylene glycol diacrylate, 1,3-butylene glycol diacrylate and the like ( (Meth) acrylic acid ester compounds; tri (meth) acrylic acid ester compounds such as trimethylolpropane trimethacrylate and trimethylolpropane triacrylate; ethylenically unsaturated monomers containing epoxy groups such as allyl glycidyl ether and glycidyl methacrylate; Etc. Among these, ethylene glycol dimethacrylate, allyl glycidyl ether, and glycidyl methacrylate are preferable, and ethylene glycol dimethacrylate is more preferable. Moreover, these may be used individually by 1 type and may be used combining two or more types by arbitrary ratios.

  The non-conductive particles including organic particles have a volume average particle diameter D50 of preferably 0.1 μm or more, more preferably 0.2 μm or more, still more preferably 0.3 μm or more, and still more preferably 0.4 μm. As described above, it is particularly preferably 0.45 μm or more, preferably 1 μm or less, more preferably 0.8 μm or less. By setting the volume average particle diameter D50 of the non-conductive particles to be equal to or greater than the lower limit of the above range, it is possible to suppress an increase in internal resistance of the functional layer and further improve the low-temperature output characteristics of the secondary battery. In addition, by setting the volume average particle diameter D50 of the nonconductive particles to be equal to or lower than the upper limit of the above range, the adhesion of the nonconductive particles can be improved, and battery characteristics such as high temperature cycle characteristics can be further improved.

Here, the organic particles that can be used as the non-conductive particles are not particularly limited, and have, for example, a core-shell structure including a core portion and a shell portion that covers (preferably partially) the outer surface of the core portion. It may be. The organic particles having a core-shell structure exhibit better adhesion in the electrolytic solution, and can favorably improve the electrical characteristics of the non-aqueous secondary battery including the functional layer. Furthermore, secondary battery members (electrodes, separators) formed by forming a functional layer on an electrode base material or separator base material may be stored and transported in a wound state, but the functional layer is formed. Even when the secondary battery substrate is rolled up, blocking (sticking of secondary battery members through the functional layer) hardly occurs, and the handling property is excellent.
In the core-shell structure described above, the core portion is a portion made of a polymer and inside the shell portion in the organic particles. The shell portion is a portion made of a polymer and covering the outer surface of the core portion, and is usually the outermost portion of the organic particles. The shell portion covers the whole or a part of the outer surface of the core portion.

When the organic particles have a core-shell structure, it is preferable to use a (meth) acrylic acid ester monomer or a (meth) acrylonitrile monomer as the monomer used for the preparation of the core polymer. It is more preferable to use an acrylate monomer. That is, the polymer of the core part preferably contains a (meth) acrylic acid ester monomer unit or a (meth) acrylonitrile monomer unit, and more preferably contains a (meth) acrylic acid ester monomer unit. It is particularly preferred that it contains a monomer unit derived from methyl methacrylate. Thereby, the ion diffusibility of the functional layer using organic particles can be further enhanced.
On the other hand, an aromatic vinyl monomer is preferred as the monomer used for the preparation of the shell polymer. That is, the polymer of the shell part preferably includes an aromatic vinyl monomer unit. Among aromatic vinyl monomers, styrene derivatives such as styrene and styrene sulfonic acid are more preferable. Thereby, the adhesiveness of the organic particles can be further enhanced.

  When the organic particles have a core-shell structure, the polymer of the core part and / or the polymer of the shell part may include an acid group-containing monomer unit. Here, as the acid group-containing monomer, a monomer having an acid group, for example, a monomer having a carboxylic acid group, a monomer having a sulfonic acid group, a monomer having a phosphoric acid group, and And a monomer having a hydroxyl group. Specific examples and preferred acid group-containing monomer units are the same as those described above.

  The organic particles having the core-shell structure described above are, for example, a step in which the monomer of the polymer in the core part and the monomer of the polymer in the shell part are used, and the ratio of these monomers is changed over time. Can be prepared by polymerization. Specifically, the organic particles can be prepared by a continuous multi-stage emulsion polymerization method and a multi-stage suspension polymerization method in which the polymer of the previous stage is sequentially coated with the polymer of the subsequent stage.

  When polymerizing the organic particles (including the core polymer and the shell polymer in the case where the organic particles have a core-shell structure), an emulsifier is used as an emulsifier according to a conventional method, for example, dodecylbenzenesulfone. Anionic surfactants such as sodium acid and sodium dodecyl sulfate, nonionic surfactants such as polyoxyethylene nonylphenyl ether and sorbitan monolaurate, or cationic surfactants such as octadecylamine acetate can be used. . Examples of the polymerization initiator include peroxides such as t-butylperoxy-2-ethylhexanoate, potassium persulfate, cumene peroxide, 2,2′-azobis (2-methyl-N- (2 An azo compound such as (hydroxyethyl) -propionamide) or 2,2′-azobis (2-amidinopropane) hydrochloride can be used.

-Binder-
The binder contained in the functional layer composition is used from the viewpoint of suppressing the components contained in the functional layer from falling off the functional layer. The binder maintains the binding between the base material and the non-conductive particles, or non-conductive particles, and suppresses the peeling of the functional layer from the base material. It is necessary that the non-conductive particles are smaller than the volume average particle diameter D50. Here, as the binder, the functional layer composition includes a particulate polymer that can exhibit higher adhesiveness than the non-conductive particles in an environment of a temperature of 25 ° C. that is not swollen in the electrolytic solution. Is preferred. By using a binder such as a particulate polymer, it is possible to suppress the components constituting the functional layer from falling off the functional layer.

And as a particulate polymer used together with the said nonelectroconductive particle, the known particulate polymer which is water-insoluble and dispersible in water, for example, a thermoplastic elastomer, is mentioned. And as a thermoplastic elastomer, a conjugated diene polymer and an acrylic polymer are preferable, and an acrylic polymer is more preferable.
Here, the conjugated diene polymer refers to a polymer containing a conjugated diene monomer unit, and specific examples of the conjugated diene polymer include aromatic vinyl monomers such as styrene-butadiene copolymer (SBR). Examples thereof include a polymer containing a monomer unit and an aliphatic conjugated diene monomer unit. Moreover, an acrylic polymer refers to the polymer containing a (meth) acrylic acid ester monomer unit.
In addition, these particulate polymers may be used individually by 1 type, and may be used in combination of 2 or more types.

  Furthermore, it is more preferable that the acrylic polymer as the particulate polymer contains a (meth) acrylonitrile monomer unit. Thereby, the intensity | strength of a functional layer can be raised.

  Here, in the acrylic polymer as the particulate polymer, the ratio of the amount of the (meth) acrylonitrile monomer unit to the total amount of the (meth) acrylonitrile monomer unit and the (meth) acrylic acid ester monomer unit Is preferably 1% by mass or more, more preferably 2% by mass or more, preferably 30% by mass or less, more preferably 25% by mass or less. By making the said ratio more than the lower limit of the said range, the intensity | strength of the acrylic polymer as a particulate polymer can be raised, and the intensity | strength of the functional layer using the said acrylic polymer can be made higher. Moreover, since the acrylic polymer as the particulate polymer is appropriately swollen with respect to the electrolytic solution by making the ratio not more than the upper limit of the above range, the ion conductivity of the functional layer is reduced and the secondary battery It is possible to suppress a decrease in the low-temperature output characteristics.

  Further, the volume average particle diameter D50 of the binder is not particularly limited as long as it is smaller than the volume average particle D50 of the non-conductive particles, but is preferably 0.01 μm or more, preferably 0.5 μm or less, more preferably. It is less than 0.45 μm, more preferably less than 0.4 μm. By making the volume average particle diameter D50 of the binder not less than the lower limit of the above range, the dispersibility of the binder can be enhanced. Moreover, the adhesiveness of a binder can be improved by making volume average particle diameter D50 below the upper limit of the said range, or less.

  And it is preferable that it is 5 mass parts or more with respect to 100 mass parts of nonelectroconductive particles, It is more preferable that it is 8 mass parts or more, and content of the binder in a functional layer is 10 mass parts or more. More preferably, it is preferably 30 parts by mass or less, more preferably 28 parts by mass or less, and still more preferably 26 parts by mass or less. By making the content of the particulate polymer as the binder more than the lower limit of the above range, the adhesiveness of the functional layer can be further enhanced. On the other hand, by setting the content of the particulate polymer as the binder to be equal to or less than the upper limit of the above range, it is possible to suppress the ion diffusibility of the functional layer from being lowered, and the battery such as the low-temperature output characteristics of the secondary battery. Characteristics can be secured.

  Examples of the method for producing the binder, particularly the particulate polymer, include a solution polymerization method, a suspension polymerization method, and an emulsion polymerization method. Among these, the emulsion polymerization method and the suspension polymerization method are preferable because polymerization can be performed in water, and an aqueous dispersion containing a particulate polymer can be suitably used as a material for the functional layer composition as it is. Moreover, when manufacturing the polymer as a particulate polymer, it is preferable that the reaction system contains a dispersing agent. The particulate polymer is usually formed by a polymer that substantially constitutes the particulate polymer, but it may be accompanied by optional components such as additives used in the polymerization.

-Other ingredients-
The composition for functional layers may contain arbitrary other components in addition to the components described above. Examples of these other components include known additives such as a wetting agent, a viscosity modifier, and an electrolytic solution additive. These other components may be used alone or in combination of two or more.

-Preparation of composition for functional layer-
Here, the method for preparing the composition for the functional layer is not particularly limited, but usually, non-conductive particles, a binder, water as a dispersion medium, a wetting agent used as necessary, and the like. The functional layer composition can be prepared by mixing with other components. Although the mixing method is not particularly limited, in order to disperse each component efficiently, mixing is usually performed using a disperser as a mixing device.
The disperser is preferably an apparatus capable of uniformly dispersing and mixing the above components. Examples include a ball mill, a sand mill, a pigment disperser, a crusher, an ultrasonic disperser, a homogenizer, and a planetary mixer. In addition, from the viewpoint of adding a high dispersion share, a high dispersion apparatus such as a bead mill, a roll mill, or a fill mix is also included.

-Application of functional layer composition on substrate-
In the composition application step, the method for applying the composition for a functional layer on the substrate is not particularly limited, and the following methods may be mentioned. :
1) A method of applying a functional layer composition on a substrate;
2) A method of immersing the substrate in the functional layer composition;
3) A method of applying the functional layer composition onto a release substrate and drying, and transferring the obtained functional layer composition on the release substrate to the surface of the substrate.
Among these, the method 1) is particularly preferable because the thickness of the functional layer can be easily controlled. Here, the method for applying the functional layer composition on the substrate is not particularly limited. For example, the spray coating method, the doctor blade method, the reverse roll method, the direct roll method, the gravure method, the extrusion method, the brush method, and the like. Examples thereof include a coating method. Of these, the gravure method and the spray coating method are preferable from the viewpoint of forming a thin functional layer.
Note that at least the methods 1) and 2) can be carried out even when the functional layer composition is powdery without containing water or the like as a dispersion medium.

<Drying process>
A drying process is a process which can be implemented especially when the composition for functional layers is a slurry form which contains water etc. as a dispersion medium. In the drying step, the method for drying the functional layer composition applied on the substrate is not particularly limited, and for example, drying with hot air or low-humidity air, vacuum drying, drying by irradiation with infrared rays, electron beams, or the like. Is mentioned. The drying conditions are not particularly limited, and the drying temperature is preferably 30 to 80 ° C., and the drying time is preferably 30 seconds to 10 minutes.

  In addition, the layer thickness of the composition for functional layers provided on the base material after the composition applying step or after the drying step when the drying step is performed is preferably 0.1 μm or more, more preferably 0. .3 μm or more, more preferably 0.5 μm or more, preferably 3 μm or less, more preferably 1.5 μm or less, and further preferably 1 μm or less. The layer thickness of the functional layer composition applied on the substrate is not less than the lower limit of the above range, so that the strength of the finally obtained functional layer can be sufficiently secured, and the upper limit of the above range. By being below the value, the ion diffusibility of the finally obtained functional layer can be ensured, and battery characteristics such as low-temperature output characteristics of the secondary battery can be improved.

<Surface activation process>
A surface activation process is a process of performing a surface activation process to the composition for functional layers provided on the base material in the previous process. By this step, a functional layer for a non-aqueous secondary battery is obtained on the substrate.
The inventor has surprisingly found that this surface activation treatment can advantageously improve the peel strength of the functional layer on the substrate. Even if the surface activation treatment is applied not to the functional layer composition but to the base material before the functional layer composition is applied, the peel strength of the functional layer cannot be improved.

  The surface activation treatment is not particularly limited as long as it is a method that can activate the surface of the composition for a functional layer provided on the substrate and does not greatly impair the structure. Specific examples of the surface activation treatment include corona discharge treatment, plasma treatment, solvent treatment, acid treatment, and ultraviolet oxidation treatment, and any treatment can improve the peel strength of the functional layer. Among these, as the surface activation treatment, corona discharge treatment and plasma treatment are preferable, and corona discharge treatment is more preferable. If corona discharge treatment or plasma discharge treatment is applied to the functional layer composition on the substrate as the surface activation treatment, the peel strength of the functional layer for the non-aqueous secondary battery is further increased with respect to the surface of the functional layer composition. Activation that can be effectively enhanced can be promoted. Further, if a functional layer subjected to corona discharge treatment or plasma treatment is used, the peel strength is further improved, so that battery characteristics such as high-temperature cycle characteristics of the obtained nonaqueous secondary battery can be further improved.

Here, when the corona discharge treatment is employed as the surface activation treatment, the discharge amount is preferably 10 W · min / m ² or more, more preferably 20 W · min / m ² or more, and 30 W It is more preferably at least min / m ^2, more preferably at most 200 W · min / m ^2, more preferably at most 150 W · min / m ² , and at most 100 W · min / m ² More preferably it is. If the discharge amount in the corona discharge treatment is 10 W · min / m ² or more, the surface of the functional layer composition on the substrate is sufficiently activated, and the peel strength of the functional layer for non-aqueous secondary batteries is effective. In addition, the high-temperature cycle characteristics of the non-aqueous secondary battery can be effectively improved by using the functional layer for non-aqueous secondary battery. Further, if the discharge amount in the corona discharge treatment is 200 W · min / m ² or less, blocking (sticking of battery members through the functional layer) occurs, and the substrate such as the separator substrate or the electrode substrate is overheated. It is possible to sufficiently suppress the occurrence of defects such as short circuit and hole opening due to.

And, in the surface activation step, a functional layer can be formed by subjecting the composition for functional layer applied on the substrate to surface activation treatment. It is preferably 50 ° or more, more preferably 53 ° or more, further preferably 55 ° or more, more preferably 80 ° or less, and even more preferably 75 ° or less, More preferably, it is 70 ° or less. If the contact angle with respect to the water of a functional layer is 80 degrees or less, moderate hydrophilicity is brought about on the functional layer surface by the surface activation treatment, and the peel strength can be further increased. Further, if the contact angle of the functional layer with respect to water is 50 ° or more, excessive hydrophilicity due to the surface activation treatment is suppressed, and blocking (functional layer) even when a battery member including the functional layer is rolled up. It is possible to make it difficult for the battery members to stick through each other.
The contact angle of the functional layer with respect to water can be adjusted by adjusting the type and amount of monomer constituting the organic particles when the non-conductive particles in the functional layer are organic particles, For example, in the case of adopting a corona discharge treatment or a plasma discharge treatment as a surface activation treatment, the amount of discharge, discharge time, voltage, and discharge electrode and treatment are adjusted. It can be adjusted by adjusting at least one of the distance to the target surface.
Moreover, the contact angle with respect to the water of the functional layer formed by the method for forming a functional layer for a non-aqueous secondary battery according to the present invention is, of course, the surface of the functional layer formed by performing the surface activation treatment. The contact angle with water.

(Method for producing non-aqueous secondary battery)
The manufacturing method of the non-aqueous secondary battery of this invention is a manufacturing method of a non-aqueous secondary battery provided with a positive electrode, a negative electrode, a separator, and electrolyte solution. Moreover, the manufacturing method of the non-aqueous secondary battery of this invention is non-aqueous by the formation method of the functional layer for non-aqueous secondary batteries of this invention mentioned above with respect to the base material selected from a separator base material and an electrode base material. Including a step of forming a functional layer for a secondary battery to produce at least one of the positive electrode, the negative electrode, and the separator, and, for example, a step of superimposing the positive electrode and the negative electrode via a separator to obtain a laminate. Then, the obtained laminate is wound in accordance with the shape of the battery as required, folded into the battery container, and filled with an electrolytic solution into the battery container for sealing. According to the method for producing a non-aqueous secondary battery of the present invention, at least one of the positive electrode, the negative electrode, and the separator is formed on the functional layer by the method for forming the functional layer for the non-aqueous secondary battery of the present invention on the substrate. Since the functional layer exhibits excellent peel strength, the functional layer and the electrode base material or separator base material and the battery member can be firmly bonded to each other. A non-aqueous secondary battery excellent in battery characteristics such as can be manufactured.
Note that an expanded metal, an overcurrent prevention element such as a fuse or a PTC element, a lead plate, or the like may be placed in the battery container to prevent an increase in pressure inside the battery or overcharge / discharge. Further, the shape of the battery may be any of a coin shape, a button shape, a sheet shape, a cylindrical shape, a square shape, a flat shape, and the like.

  Here, in the method for manufacturing a non-aqueous secondary battery of the present invention, the non-aqueous secondary battery may be a wound type or a stacked type. That is, the method for producing a non-aqueous secondary battery of the present invention can be preferably applied to the production of a wound or stacked non-aqueous secondary battery. Usually, in the production of a wound-type or stacked-type non-aqueous secondary battery, it is necessary to bond battery members such as electrodes and separators. If the functional layer is formed by the method for forming a functional layer for a non-aqueous secondary battery of the present invention, battery members such as electrodes and separators are firmly bonded to each other, and battery characteristics such as high-temperature cycle characteristics are excellent. A wound or stacked non-aqueous secondary battery can be manufactured.

In the method for producing a non-aqueous secondary battery, as the positive electrode, negative electrode and separator having no functional layer for non-aqueous secondary battery, known positive electrodes, negative electrodes and separators used in non-aqueous secondary batteries are used. Can be used. As the electrolytic solution, a known electrolytic solution used in a non-aqueous secondary battery can be used.
Specifically, as the electrode (positive electrode and negative electrode) not having the above-mentioned non-aqueous secondary battery functional layer, the electrode base material described above in the section “Method for forming non-aqueous secondary battery functional layer”. As the separator having no functional layer for a non-aqueous secondary battery as described above, the separator substrate described in the section “Method for forming a functional layer for a non-aqueous secondary battery” may be used. it can.

As the electrolytic solution, an organic electrolytic solution in which a supporting electrolyte is dissolved in an organic solvent is usually used. For example, when the non-aqueous secondary battery is a lithium ion secondary battery, a lithium salt is used as the supporting electrolyte. 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 the like. Of these, LiPF ₆ , LiClO ₄ , and CF ₃ SO ₃ Li are preferable, and LiPF ₆ is particularly preferable because it is easily dissolved in a solvent and exhibits a high degree of dissociation. 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.

Further, the organic solvent used in the electrolytic solution is not particularly limited as long as it can dissolve the supporting electrolyte. For example, dimethyl carbonate (DMC), ethylene carbonate (EC), diethyl carbonate (DEC), propylene carbonate (PC) ), Carbonates such as butylene carbonate (BC), ethyl methyl carbonate (EMC), vinylene carbonate (VC); esters such as γ-butyrolactone and methyl formate; ethers such as 1,2-dimethoxyethane and tetrahydrofuran; sulfolane And sulfur-containing compounds such as dimethyl sulfoxide; Moreover, you may use the liquid mixture of these solvents. Among them, it is preferable to use carbonates because they have a high dielectric constant and a wide stable potential region, and it is more preferable to use a mixture of ethylene carbonate and ethyl methyl carbonate.
In addition, the density | concentration of the electrolyte in electrolyte solution can be adjusted suitably, for example, it is preferable to set it as 0.5-15 mass%, it is more preferable to set it as 2-13 mass%, and it shall be 5-10 mass%. Is more preferable. Further, known additives such as fluoroethylene carbonate and ethyl methyl sulfone may be added to the electrolytic solution.

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 addition, in a polymer produced by copolymerizing a plurality of types of monomers, the proportion of the structural unit formed by polymerizing a certain monomer in the polymer is usually that unless otherwise specified. This coincides with the ratio (preparation ratio) of the certain monomer in the total monomers used for polymerization of the polymer.
In addition, in the functional layer obtained by appropriately performing a surface activation treatment using a composition for a functional layer containing non-conductive particles, a binder, and any other components, at least the non-conductive particles and the binder Unless otherwise noted, the ratio generally matches the blending ratio (preparation ratio) of the non-conductive particles and the binder used in the preparation of the functional layer composition.
In Examples and Comparative Examples, the volume average particle diameter D50 of the non-conductive particles and the binder, the contact angle of the functional layer with water, the adhesion between the electrode and the separator (peel strength of the functional layer), and blocking resistance The high-temperature cycle characteristics and the reliability of the substrate with a functional layer were measured and evaluated by the following methods.

<Volume average particle diameter D50 of non-conductive particles and binder>
The volume average particle diameter D50 of the non-conductive particles and the binder is a laser diffraction particle size distribution measuring apparatus (product name “LS” manufactured by Beckman Coulter, Inc.) of an aqueous dispersion adjusted to a solid content concentration of 15% by mass. In the particle size distribution measured by -230 "), the particle size was such that the cumulative volume calculated from the small diameter side was 50%.

<Contact angle of functional layer to water>
Using Drop Master DM500 manufactured by Kyowa Interface Science Co., Ltd., set the separator (separator substrate with functional layer) on the table so that the functional layer is on top, and then ion exchange as a liquid for surface tension measurement. 1 μL of water (1.0 μS · cm) was dropped, and the contact angle was measured by a droplet method 60 seconds after the landing. The evaluation results are shown in Table 1.

<Adhesiveness between electrode and separator (peel strength of functional layer)>
A separator similar to the separator (separator substrate with a functional layer) prepared in each example and comparative example, and a positive substrate and negative electrode substrate prepared in each example or comparative example were prepared. And the laminated body of a positive electrode base material and a separator, and the laminated body of a negative electrode base material and a separator were produced, and it cut out to 10 mm width, respectively, and obtained the test piece.
This test piece was pressed under the conditions of 70 ° C., 1.0 MPa, and 8 seconds to obtain an integrated product in which the electrode and the separator were integrated. Then, the cellophane tape was affixed on the surface of this electrode with the surface of the electrode (positive electrode or negative electrode) facing down. At this time, a cellophane tape defined in JIS Z1522 was used. The cellophane tape was fixed on a horizontal test bench. Thereafter, the stress was measured when one end of the separator was pulled vertically upward at a pulling speed of 50 mm / min and peeled off. This measurement was carried out three times for each of the positive electrode substrate and separator laminate and the negative electrode substrate and separator laminate for a total of six times, and the average value of the measured stress was determined to be the peel strength. And it evaluated on the following references | standards. The evaluation results are shown in Table 1.
A: Peel strength is 10 N / m or more B: Peel strength is 5 N / m or more and less than 10 N / m C: Peel strength is 3 N / m or more and less than 5 N / m D: Peel strength is less than 3 N / m

<Blocking resistance>
The separators prepared in the examples and comparative examples were cut into squares with a side of 5 cm and squares with a side of 4 cm to obtain test pieces. A sample obtained by superimposing these two sheets “a sample in an unpressed state” and a sample “pressed sample” placed under pressure of 40 g and 10 g / cm ² after superposing these two sheets were produced. Each of these samples was left for 24 hours. In the sample after being left for 24 hours, the adhesion state (blocking state) between the stacked separators was visually confirmed. And blocking resistance was evaluated on the following reference | standard. The evaluation results are shown in Table 1.
A: Separator is not blocked in “unpressed sample” and “pressed sample” B: Separator is not blocked in “unpressed sample” and “pressed sample” ", Separators are blocking each other (but can be removed by hand)
C: Separators are not blocked in the “unpressed sample”, and separators are blocked in the “pressed sample” (cannot be peeled off by hand)
D: Separator is blocked in “unpressed sample” and “pressed sample”

<High temperature cycle characteristics>
The 800 mAh wound type lithium ion secondary battery manufactured in the examples and comparative examples was allowed to stand in an environment of 25 ° C. for 24 hours. Thereafter, under an environment of 25 ° C., a charge / discharge operation of charging up to 4.35 V at 0.1 C and discharging to 2.75 V at 0.1 C was performed, and the initial capacity C0 was measured.
Furthermore, charging and discharging were repeated 1000 cycles under the same conditions as described above in a 60 ° C. environment, and the capacity C1 after 1000 cycles was measured. The capacity retention rate ΔC was calculated by ΔC = C1 / C0 × 100 (%). And it evaluated on the following references | standards. The evaluation results are shown in Table 1. The higher the capacity retention ratio ΔC, the better the high-temperature cycle characteristics of the secondary battery and the longer the battery life.
A: Capacity maintenance ratio ΔC is 84% or more B: Capacity maintenance ratio ΔC is 80% or more and less than 84% C: Capacity maintenance ratio ΔC is 75% or more and less than 80% D: Capacity maintenance ratio ΔC is less than 75%

<Reliability of base material with functional layer>
The separator (separator base material with a functional layer) prepared in Examples and Comparative Examples was punched into a circle having a diameter of 19 mm. This circular separator was impregnated with an electrolytic solution, sandwiched between a pair of circular SUS plates (diameter 15.5 mm), and superposed in a configuration of (SUS plate) / (circular separator) / (SUS plate). Here, as an electrolytic solution, LiPF ₆ was added at 1 mol / liter to a mixed solvent obtained by mixing ethylene carbonate (EC) and diethyl carbonate (DEC) at EC: DEC = 1: 2 (volume ratio at 20 ° C.). A solution dissolved at a concentration of 1 liter was used. This was enclosed in a 2032 type coin cell, a lead wire was taken from the coin cell, and a thermocouple was attached and placed in an oven. Then, while applying an alternating current with an amplitude of 10 mV and a frequency of 1 kHz, the temperature was raised to 200 ° C. at a rate of temperature rise of 1.6 ° C./min, and the cell resistance during this time was measured to confirm the occurrence of a short circuit. This test was conducted 10 times and evaluated according to the following criteria. The evaluation results are shown in Table 1. It shows that it is excellent in the reliability of a base material with a functional layer, so that generation | occurrence | production of a short circuit is few.
A: 0 occurrences of short circuit B: 1 to 3 occurrences of short circuit C: 4 to 7 occurrences of short circuit D: 8 to 10 occurrences of short circuit

Example 1
<Preparation of non-conductive particles>
In a 5 MPa pressure vessel with a stirrer, 60 parts of methyl methacrylate as a (meth) acrylic acid ester monomer and 35 parts of butyl acrylate, 4 parts of methacrylic acid as an acid group-containing monomer, as a crosslinkable monomer 1 part of ethylene dimethacrylate; 1 part of sodium dodecylbenzenesulfonate as an emulsifier; 150 parts of ion-exchanged water and 0.5 part of potassium persulfate as a polymerization initiator were added and sufficiently stirred. Then, it heated at 80 degreeC and superposition | polymerization was started. When the polymerization conversion rate reached 96%, the reaction was stopped by cooling to prepare an aqueous dispersion containing organic particles as non-conductive particles.
In addition, it was 0.45 micrometer when the volume average particle diameter D50 of the obtained nonelectroconductive particle was measured.

<Preparation of binder>
70 parts of ion-exchanged water, 0.15 part of sodium lauryl sulfate (product name “Emal 2F” manufactured by Kao Chemical Co., Ltd.) as an emulsifier, and 0.5 part of ammonium persulfate are supplied to a reactor equipped with a stirrer. The gas phase portion was replaced with nitrogen gas, and the temperature was raised to 60 ° C.
On the other hand, in a separate container, 50 parts of ion-exchanged water, 0.5 part of sodium dodecylbenzenesulfonate as a dispersant, 95 parts of butyl acrylate as a (meth) acrylic acid ester monomer, 2 parts of acrylonitrile, methacrylic acid 2 parts and 1 part of N-methylolacrylamide were mixed to obtain a monomer mixture. This monomer mixture was continuously added to the reactor described above over 4 hours for polymerization. During the addition, the reaction was performed at 60 ° C. After completion of the addition, the reaction was further terminated by stirring at 70 ° C. for 3 hours to prepare an aqueous dispersion containing a particulate polymer as a binder.
In addition, it was 0.36 micrometer when the volume average particle diameter D50 of the obtained binder was measured.

<Preparation of non-aqueous secondary battery functional layer composition>
For 100 parts of aqueous dispersion containing organic particles as the non-conductive particles (corresponding to solid content), 14 parts of aqueous dispersion containing particulate polymer as the binder (corresponding to solid content), viscosity 2 parts of ethylene oxide-propylene oxide copolymer (solid content concentration: 70 mass%, polymerization ratio: 5/5 (mass ratio)) as a regulator (corresponding to solid content) and 1,2-benzisothiazoline-3-one (Solid content concentration: 5.0% by mass) 0.0005 part (corresponding to solid content) is mixed, and ion-exchanged water is further mixed so that the solid content concentration is 15% by mass. A battery functional layer composition was prepared.

<Preparation of separator>
A polyethylene porous substrate (thickness: 16 μm, Gurley value: 210 s / 100 cc) was prepared as a separator substrate. On the both surfaces of this separator base material, the above-mentioned composition for functional layers was apply | coated by the spray coat method, and was dried at 50 degreeC for 1 minute. Thus, a layer having a thickness of 1 μm per layer was formed on the separator base material to obtain a coated separator.
The coated surface of the resulting coated separator (the surface coated with the functional layer composition) is subjected to corona discharge treatment with a discharge amount of 50 W · min / m ² to form functional layers on both sides of the separator substrate. A separator (separator substrate with a functional layer) was prepared.
Using the obtained separator, the contact angle of the functional layer with respect to water, the blocking resistance, and the reliability of the substrate with the functional layer were measured or evaluated. The results are shown in Table 1.

<Preparation of negative electrode substrate>
In a 5 MPa pressure vessel with a stirrer, 33.5 parts of 1,3-butadiene, 3.5 parts of itaconic acid, 62 parts of styrene, 1 part of 2-hydroxyethyl acrylate, 0.4 part of sodium dodecylbenzenesulfonate as an emulsifier, After adding 150 parts of ion exchange water and 0.5 part of potassium persulfate as a polymerization initiator and stirring sufficiently, the mixture was heated to 50 ° C. to initiate polymerization. When the polymerization conversion rate reached 96%, the reaction was stopped by cooling to obtain a mixture containing the particulate binder (SBR). A 5% aqueous sodium hydroxide solution was added to the mixture containing the particulate binder to adjust to pH 8, and then the unreacted monomer was removed from the mixture by heating under reduced pressure. Then, it cooled to 30 degrees C or less, and obtained the water dispersion liquid containing a desired particulate-form binder.
Next, 100 parts of artificial graphite (volume average particle diameter D50: 15.6 μm) as a negative electrode active material, 2% aqueous solution of carboxymethyl cellulose sodium salt (“MAC350HC” manufactured by Nippon Paper Industries Co., Ltd.) as a thickener 1 part and ion-exchanged water were added to adjust the solid content concentration to 68%, followed by mixing at 25 ° C. for 60 minutes to obtain a mixed solution. After adding ion exchange water to this liquid mixture and adjusting solid content concentration to 62%, it mixed for 15 minutes at 25 degreeC further. Next, 1.5 parts of an aqueous dispersion containing the above-mentioned particulate binder is added to this mixed liquid in an amount corresponding to the solid content, and ion-exchanged water is further added to adjust the final solid content concentration to 52%. And further mixed for 10 minutes. This was defoamed under reduced pressure to obtain a negative electrode slurry composition having good fluidity.
And this slurry composition for negative electrodes was apply | coated and dried so that the film thickness after drying might be set to about 150 micrometers on the copper foil with a thickness of 20 micrometers which is a collector with a comma coater. This drying was performed by conveying the copper foil in an oven at 60 ° C. at a speed of 0.5 m / min for 2 minutes. Thereafter, heat treatment was performed at 120 ° C. for 2 minutes to obtain a negative electrode raw material before pressing. The negative electrode raw material before pressing was rolled with a roll press to obtain a negative electrode substrate after pressing with a negative electrode mixture layer having a thickness of 80 μm.

<Preparation of positive electrode substrate>
100 parts of LiCoO ₂ (volume average particle diameter D50: 12 μm) as a positive electrode active material, ₂ parts of acetylene black (product name “HS-100”, manufactured by Denki Kagaku Kogyo Co., Ltd.) as a conductive material, and a binder 2 parts of polyvinylidene fluoride (manufactured by Kureha Co., Ltd., product name “# 7208”) was mixed in an amount corresponding to the solid content, and N-methylpyrrolidone was added thereto to make the total solid content concentration 70%. These were mixed by a planetary mixer to obtain a positive electrode slurry composition.
And this slurry composition for positive electrodes was apply | coated and dried so that the film thickness after drying might be set to about 150 micrometers on the aluminum foil with a thickness of 20 micrometers which is a collector with a comma coater. This drying was performed by conveying the aluminum foil in an oven at 60 ° C. at a speed of 0.5 m / min for 2 minutes. Thereafter, heat treatment was performed at 120 ° C. for 2 minutes to obtain a positive electrode raw material before pressing. The positive electrode raw material before pressing was rolled with a roll press to obtain a positive electrode base material after pressing with a positive electrode mixture layer thickness of 80 μm.

<Manufacture of non-aqueous secondary batteries>
The positive electrode substrate obtained above was cut into 49 cm × 5 cm. Subsequently, the separator obtained above was cut out to 55 cm × 5.5 cm, and this was placed on the positive electrode mixture layer of the cut out positive electrode base material. Furthermore, the negative electrode base material obtained above was cut out to 50 cm × 5.2 cm, and this was separated from the surface of the separator on the side opposite to the side where the positive electrode base material was arranged, on the surface on the negative electrode mixture layer side. Was placed so as to face the separator, and this was wound by a winding machine to obtain a wound body. The wound body was pressed at 70 ° C. and 1.0 MPa for 8 seconds to obtain a flat body. This flat body is wrapped with an aluminum wrapping case as a battery case, and an electrolytic solution (solvent: ethylene carbonate / diethyl carbonate / vinylene carbonate (volume mixing ratio) = 68.5 / 30 / 1.5, electrolyte: concentration 1M) LiPF ₆ ) was injected so that no air remained. Further, in order to seal the opening of the aluminum packaging material, heat sealing at 150 ° C. was performed to close the aluminum exterior. Thereby, a wound lithium ion secondary battery having a discharge capacity of 800 mAh was manufactured.
Using the obtained wound type lithium ion secondary battery, the high-temperature cycle characteristics were evaluated. The results are shown in Table 1.

(Examples 2 to 4)
In the same manner as in Example 1 except that the amount of discharge in the corona discharge treatment applied to the coated surface of the coated separator during the preparation of the separator was changed as shown in Table 1, non-conductive particles, binders The composition for a non-aqueous secondary battery functional layer, a separator, a negative electrode, a positive electrode, and a non-aqueous secondary battery were produced. Various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Example 1)
At the time of preparing the separator, a corona discharge treatment is applied to the surface of the separator base material before applying the functional layer composition, and then the functional layer composition is spray coated on both surfaces of the separator base material. In the same manner as in Example 1 except that a separator was prepared by drying at 50 ° C. for 1 minute, non-conductive particles, binder, composition for non-aqueous secondary battery functional layer, separator, negative electrode A positive electrode and a non-aqueous secondary battery were manufactured. Various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Example 2)
In the same manner as in Example 1 except that the coated surface of the coated separator was not subjected to corona discharge treatment when the separator was prepared, the composition for the non-conductive particles, the binder, and the non-aqueous secondary battery functional layer Products, separators, negative electrodes, positive electrodes, and non-aqueous secondary batteries were produced. Various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

From Table 1 above, a functional layer composition containing non-conductive particles and a binder is applied, and the functional layer composition applied on the substrate is subjected to a surface activation treatment to provide a non-aqueous secondary battery. It can be seen that in Examples 1 to 4 in which the functional layer is formed, the electrode and the separator are firmly bonded, and the peel strength of the functional layer is excellent.
In addition, from Examples 1 to 4 in Table 1 above, by adjusting the discharge amount in the corona discharge treatment, the peel strength of the functional layer, blocking resistance, high-temperature cycle characteristics, and the reliability of the substrate with the functional layer are improved. It can be seen that it can be juxtaposed at a high level.

  In each of the above examples, corona discharge treatment was used as the surface activation treatment. However, the peel strength of the functional layer can be improved by using other surface activation treatments as listed in this specification. Can be made.

ADVANTAGE OF THE INVENTION According to this invention, the formation method of the functional layer for non-aqueous secondary batteries which can form the functional layer for non-aqueous secondary batteries which has the outstanding peel strength can be provided.
Moreover, according to this invention, the manufacturing method of the non-aqueous secondary battery which can manufacture the non-aqueous secondary battery excellent in battery characteristics, such as a high temperature cycling characteristic, can be provided.

Claims (6)

Providing a functional layer composition comprising a binder having a volume average particle diameter D50 smaller than the volume average particle diameter D50 of the nonconductive particles and the nonconductive particles on the substrate;
A method for forming a functional layer for a non-aqueous secondary battery, comprising a step of subjecting the composition for a functional layer applied on the substrate to a surface activation treatment.   The method for forming a functional layer for a non-aqueous secondary battery according to claim 1, wherein the surface activation treatment is corona discharge treatment or plasma discharge treatment. The function for a non-aqueous secondary battery according to claim 2, wherein the surface activation treatment is a corona discharge treatment, and a discharge amount in the corona discharge treatment is 10 W · min / m ² or more and 200 W · min / m ² or less. Layer formation method.   The formation method of the functional layer for non-aqueous secondary batteries as described in any one of Claims 1-3 whose contact angle with respect to the water of the said functional layer is 50 degrees or more and 80 degrees or less. A method for producing a non-aqueous secondary battery comprising a positive electrode, a negative electrode, a separator and an electrolyte solution,
A functional layer is formed by a method according to any one of claims 1 to 4 on a substrate selected from a separator substrate and an electrode substrate to produce at least one of the positive electrode, the negative electrode, and the separator. The manufacturing method of a non-aqueous secondary battery including the process to do.   The method for producing a non-aqueous secondary battery according to claim 5, wherein the non-aqueous secondary battery is a wound type or a stacked type.