JP7107137B2 - Slurry composition for non-aqueous secondary battery negative electrode, negative electrode for non-aqueous secondary battery, and non-aqueous secondary battery - Google Patents

Description

TECHNICAL FIELD The present invention relates to a slurry composition for non-aqueous secondary battery negative electrode, a negative electrode for non-aqueous secondary battery, and a non-aqueous secondary battery.

Non-aqueous secondary batteries such as lithium-ion secondary batteries (hereinafter sometimes simply referred to as "secondary batteries") are characterized by their small size, light weight, high energy density, and the ability to be charged and discharged repeatedly. Yes, it is used for a wide range of purposes. Therefore, in recent years, improvements in battery members such as electrodes have been studied for the purpose of further improving the performance of non-aqueous secondary batteries.

Here, an electrode used in a secondary battery such as a lithium ion secondary battery usually includes a current collector and an electrode mixture layer (a positive electrode mixture layer or a negative electrode mixture layer) formed on the current collector. It has Then, this electrode mixture layer is formed by, for example, applying a slurry composition containing an electrode active material and a binder composition containing a binder onto a current collector and drying the applied slurry composition. It is formed.

Therefore, in recent years, attempts have been made to improve the slurry composition and binder composition used for forming the electrode mixture layer in order to further improve the performance of the secondary battery.
Specifically, for example, in Patent Document 1, a binder containing a particulate polymer containing a predetermined proportion of aromatic vinyl monomer units and a predetermined proportion of ethylenically unsaturated carboxylic acid monomer units, Disclosed is a lithium ion secondary battery negative electrode slurry comprising a negative electrode active material and a water-soluble polymer. Such a particulate polymer has a surface acidity of at least a predetermined value and a contact angle with a mixed solvent of ethylene carbonate and diethyl carbonate (volume ratio: ethylene carbonate/diethyl carbonate=1/2) of 50° or less. characterized by being Further, for example, in Patent Document 2, a water-soluble polymer and water are included, the contact angle of the water-soluble polymer with water is 40 ° or more and 80 ° or less, and the swelling degree of the water-soluble polymer with respect to the electrolyte solution is more than 1.0 times and 3.0 times or less, a binder composition for a nonaqueous secondary battery functional layer.

WO2013/191239 WO2017/183641

Here, from the viewpoint of improving battery characteristics such as output characteristics, the electrode of the secondary battery should be excellent in electrolyte pourability (hereinafter sometimes referred to as electrolyte pourability). It has been demanded. In addition, with the recent expansion of the use of secondary batteries, secondary batteries are required to be able to secure a sufficient charge capacity even when charging is performed in a low temperature environment, that is, to have excellent low-temperature charge acceptance. ing.

However, with the conventional negative electrode slurry or binder composition, it was not possible to form a negative electrode that has sufficiently high electrolyte pourability and that can sufficiently improve the low-temperature charge acceptance of the obtained secondary battery. .

Accordingly, an object of the present invention is to provide a slurry composition for a non-aqueous secondary battery negative electrode capable of forming a negative electrode for a non-aqueous secondary battery having excellent electrolyte pourability.
Another object of the present invention is to provide a negative electrode for a non-aqueous secondary battery that is excellent in electrolyte pourability and that can improve the low-temperature charge acceptability of the resulting secondary battery.
Another object of the present invention is to provide a non-aqueous secondary battery that has a negative electrode for a non-aqueous secondary battery that is excellent in electrolyte pourability and that is excellent in low-temperature charge acceptance.

The inventor of the present invention has made intensive studies with the aim of solving the above problems. Further, the present inventors found that if a slurry composition for a negative electrode containing a binder having a contact angle with an electrolytic solution and a degree of swelling with respect to the electrolytic solution each within a predetermined range and a negative electrode active material is used, the electrolytic solution can be injected. The present inventors have found that it is possible to form a negative electrode for a non-aqueous secondary battery having excellent properties. In addition, the inventors have found that a non-aqueous secondary battery having such a negative electrode for a non-aqueous secondary battery is excellent in low-temperature charging acceptability. Based on these new findings, the present inventor completed the present invention.

That is, an object of the present invention is to advantageously solve the above-mentioned problems, and a slurry composition for a non-aqueous secondary battery negative electrode of the present invention is a non-aqueous secondary battery containing a binder and a negative electrode active material. A slurry composition for a battery negative electrode, wherein the binder comprises a particulate polymer, and the binder contains LiPF ₆ having a concentration of 1 mol/L and a volume ratio of ethylene carbonate and ethyl methyl carbonate of 3: A contact angle with an electrolytic solution containing a mixed solvent of No. 7 is 50° or less, and a degree of swelling of the binder with respect to the electrolytic solution is 110% or more and 300% or less. As described above, a non-aqueous two-component binder containing a particulate polymer and having a contact angle and a degree of swelling with respect to an electrolytic solution within predetermined ranges, and a negative electrode active material. By using the slurry composition for the negative electrode of a secondary battery, it is possible to form a negative electrode for a non-aqueous secondary battery that is excellent in electrolyte pourability.
The "contact angle with the electrolytic solution" of the binder and the "degree of swelling with respect to the electrolytic solution" of the binder can be measured using the methods described in the examples of the present specification.

Here, in the slurry composition for a non-aqueous secondary battery negative electrode of the present invention, the particulate polymer comprises an aromatic vinyl block region composed of an aromatic vinyl monomer unit and an aliphatic conjugated diene monomer unit. It is preferably a copolymer containing other regions containing If the particulate polymer contains aromatic vinyl block regions composed of aromatic vinyl monomer units and other regions containing aliphatic conjugated diene monomer units, the slurry composition can be used. It is possible to further improve the electrolyte pourability of the obtained negative electrode.
The "monomer unit" of the polymer means "a repeating unit derived from the monomer and contained in the polymer obtained using the monomer". In addition, the phrase "a polymer has a block region composed of monomer units" means that "there is a portion in which only the monomer units are linked and bonded as repeating units in the polymer". do.

In addition, in the slurry composition for a non-aqueous secondary battery negative electrode of the present invention, the particulate polymer may further contain a coupling site.
In the present invention, the "coupling site" in the polymer means "a site derived from the coupling agent contained in the polymer obtained through a coupling reaction using a coupling agent". .

Further, in the slurry composition for a non-aqueous secondary battery negative electrode of the present invention, the negative electrode active material preferably has a tap density of 0.70 g/cm ³ or more and 1.10 g/cm ³ or less. If the tap density of the negative electrode active material is 0.70 g/cm ³ or more and 1.10 g/cm ³ or less, the electrolyte pourability and density of the obtained negative electrode can be enhanced.
The "tap density of the negative electrode active material" can be measured according to the method described in Examples.

Another object of the present invention is to advantageously solve the above-described problems. and a negative electrode mixture layer having a density of 1.60 g/cm ³ or more. In this way, the negative electrode for non-aqueous secondary batteries includes a negative electrode mixture layer having a density of 1.60 g/cm ³ or more, which is formed using any of the slurry compositions for non-aqueous secondary battery negative electrodes described above. With such a negative electrode, when a secondary battery is formed using such a negative electrode, the obtained secondary battery has a high energy density and a high capacity. 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.

An object of the present invention is to advantageously solve the above-mentioned problems. A non-aqueous secondary battery of the present invention comprises a positive electrode, a negative electrode, a separator and an electrolytic solution, wherein the negative electrode is the above-described non-aqueous secondary battery. It is characterized by being a negative electrode for an aqueous secondary battery. By using the negative electrode for a non-aqueous secondary battery described above, a non-aqueous secondary battery having excellent electrolyte pourability and low-temperature charge acceptance can be efficiently produced.

ADVANTAGE OF THE INVENTION According to this invention, the slurry composition for non-aqueous secondary battery negative electrodes which can form the negative electrode for non-aqueous secondary batteries which is excellent in electrolyte injection property can be provided.
Moreover, according to the present invention, it is possible to provide a negative electrode for a non-aqueous secondary battery that is excellent in electrolyte pourability and that can improve the low-temperature charge acceptability of the resulting secondary battery.
According to the present invention, it is possible to provide a non-aqueous secondary battery that has a negative electrode for a non-aqueous secondary battery that is excellent in electrolyte pourability and that is excellent in low-temperature charge acceptance.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail.
Here, the slurry composition for a non-aqueous secondary battery negative electrode of the present invention can be used when producing a negative electrode for a non-aqueous secondary battery such as a lithium ion secondary battery. Furthermore, the non-aqueous secondary battery of the present invention is characterized by using the negative electrode for non-aqueous secondary batteries of the present invention formed using the slurry composition for non-aqueous secondary battery negative electrodes of the present invention.

(Slurry composition for non-aqueous secondary battery negative electrode)
The slurry composition for a non-aqueous secondary battery negative electrode of the present invention contains a particulate polymer, optionally a viscosity-increasing component such as a water-soluble polymer, and other components that can be blended in the slurry composition. contains. Moreover, the slurry composition for non-aqueous secondary battery negative electrodes of this invention normally further contains dispersion media, such as water. A binding material containing a particulate polymer, wherein the contact angle and the degree of swelling with respect to the electrolytic solution are each within a predetermined range, and for a negative electrode of a non-aqueous secondary battery containing a negative electrode active material. By using the slurry composition, it is possible to form a negative electrode for a non-aqueous secondary battery that is excellent in electrolyte pourability.

The reason why a slurry composition for a non-aqueous secondary battery negative electrode capable of forming a negative electrode for a non-aqueous secondary battery having excellent electrolyte pourability is obtained is not clear, but is presumed to be as follows. be done. That is, since the slurry composition of the present invention contains a binder whose contact angle and degree of swelling with respect to the electrolytic solution are within a predetermined range, the negative electrode formed using such a slurry composition has an affinity with the electrolytic solution. Because it is rich in Further, a secondary battery having such a negative electrode has excellent low-temperature charging acceptability because the electrolytic solution can move satisfactorily inside the battery even in a low-temperature environment. Furthermore, since the binding material does not swell excessively with respect to the electrolyte, the mobility of the electrolyte inside the secondary battery can be enhanced, and as a result, the charge acceptance of the secondary battery can be enhanced. can. Furthermore, by including the particulate polymer in the binder, a suitable gap is maintained between the particulate polymers in the negative electrode, and the electrolyte pourability of the negative electrode can be enhanced.

<Binder>
The binder contained in the slurry composition of the present invention contains a particulate polymer, and optionally, a "particulate binder" which is another polymer having a different composition and properties from the particulate polymer. can include The _binder of the present invention contains a particulate polymer, and has a contact angle of As long as the angle is 50° or less and the degree of swelling with respect to the electrolytic solution is 110% or more and 300% or less, a particulate polymer of any composition and any particulate binder can be included.

The "binder" contained in the slurry composition of the present invention holds components such as the negative electrode active material in the negative electrode mixture layer formed using the slurry composition so as not to detach from the negative electrode mixture layer. In addition, it consists of one or more components that enable adhesion between the negative electrode and the separator via the negative electrode mixture layer. More specifically, the "binder" may comprise one or more particulate polymers that are water-insoluble. Specifically, the particulate polymer includes <<particulate polymer>> and <<particulate binder>> described in detail below. These are different in composition and/or properties. As long as the conditions of the contact angle and the degree of swelling described above are satisfied, the "binder" may contain only the "particulate polymer" without any particular limitation. It may also include "particulate polymer" and "particulate binder". In addition, the fact that the polymer is “water-insoluble” means that when 0.5 g of the polymer is dissolved in 100 g of water at a temperature of 25° C., the insoluble content is 90% by mass or more.
The properties of the binder of the present invention, the composition of the particulate polymer, the composition of the particulate binder, and the like are described in detail below.

<<Contact angle to electrolyte>>
The binder is an electrolytic solution containing LiPF ₆ at a concentration of 1 mol/L and a mixed solvent of ethylene carbonate and ethyl methyl carbonate at a volume ratio of 3:7 (hereinafter simply It is necessary that the contact angle with respect to the electrolyte) is 50° or less. If the contact angle of the binder with respect to the electrolytic solution is equal to or less than the above upper limit, the electrolytic solution can easily move in the formed negative electrode mixture layer, and a negative electrode having excellent electrolyte injection properties can be obtained. Furthermore, from the viewpoint of further enhancing the effect of improving the pourability of the electrolyte, the contact angle of the binder with respect to the electrolyte is preferably 48° or less, more preferably 45° or less. The contact angle of the binder with respect to the electrolytic solution is not particularly limited, and may be, for example, 20° or more.

<< Degree of swelling with respect to electrolyte >>
The binder should have a degree of swelling of 110% or more and 300% or less with respect to an electrolytic solution containing LiPF ₆ at a concentration of 1 mol/L and a mixed solvent of ethylene carbonate and ethyl methyl carbonate at a volume ratio of 3:7. . If the degree of swelling with respect to the electrolytic solution is at least the above lower limit, the binding material swells appropriately with respect to the electrolytic solution, so that ions that contribute to the battery reaction inside the secondary battery can easily move, and the secondary It is possible to prevent the internal resistance of the battery from becoming excessively high. Further, if the degree of swelling with respect to the electrolytic solution is equal to or less than the above upper limit, the electrolytic solution easily moves in the negative electrode mixture layer, and some of the ions that contribute to the battery reaction (for example, lithium in the lithium ion secondary battery ion) can be suppressed from being deposited as a metal in the negative electrode or on the surface of the negative electrode. In addition, since the electrolyte easily moves in the negative electrode mixture layer, the low-temperature charge acceptability of the secondary battery including such a negative electrode mixture layer can be improved. Furthermore, from the viewpoint of further enhancing the various effects as described above, the degree of swelling of the binder with respect to the electrolytic solution is more preferably 120% or more, more preferably 250% or less, and 200% or less. It is even more preferable to have

<<particulate polymer>>
[Polymer]
The polymer forming the particulate polymer includes an aromatic vinyl block region composed of aromatic vinyl monomer units and other regions containing aliphatic conjugated diene monomer units (hereinafter simply "other regions" It is preferably a copolymer containing If the particulate polymer is such a copolymer, the electrolyte pourability of the negative electrode obtained using the slurry composition can be further enhanced.
In the polymer, the aromatic vinyl block region and other regions are adjacent to each other. Also, the polymer may have only one aromatic vinyl block region, or may have a plurality of them. Similarly, the polymer may have only one other region, or may have more than one.

-Aromatic vinyl block region-
The aromatic vinyl block region is a region containing only aromatic vinyl monomer units as repeating units, as described above.
Here, one aromatic vinyl block region may be composed of only one type of aromatic vinyl monomer unit, or may be composed of a plurality of types of aromatic vinyl monomer units. , preferably composed of only one aromatic vinyl monomer unit.
In addition, one aromatic vinyl block region may contain a coupling site (that is, the aromatic vinyl monomer units constituting one aromatic vinyl block region are may be consecutive).
Then, when the polymer has a plurality of aromatic vinyl block regions, the types and proportions of the aromatic vinyl monomer units constituting the plurality of aromatic vinyl block regions may be the same or different. is preferably

Examples of aromatic vinyl monomers capable of forming the aromatic vinyl monomer units constituting the aromatic vinyl block region of the polymer include styrene, styrenesulfonic acid and salts thereof, α-methylstyrene, pt -butylstyrene, butoxystyrene, vinyltoluene, chlorostyrene, and aromatic monovinyl compounds such as vinylnaphthalene. Among them, styrene is preferred. These can be used singly or in combination of two or more, but it is preferable to use one kind alone.

The proportion of aromatic vinyl monomer units in the polymer is 2% by mass or more when the amount of all repeating units (monomer units and structural units) in the polymer is 100% by mass. is preferably 10% by mass or more, more preferably 15% by mass or more, preferably 50% by mass or less, more preferably 45% by mass or less, 40% by mass More preferably: When the proportion of the aromatic vinyl monomer unit in the polymer is 2% by mass or more, the development of tackiness of the polymer can be sufficiently suppressed. Therefore, even when the negative electrode is subjected to pressure treatment by roll pressing for the purpose of increasing the density of the negative electrode mixture layer of the negative electrode, the negative electrode mixture layer adheres to the roll, which causes defects and productivity. It is possible to suppress the occurrence of a decrease in On the other hand, if the proportion of the aromatic vinyl monomer units in the polymer is 50% by mass or less, the flexibility of the polymer is ensured, and the density can be easily increased when the negative electrode is pressed.
Incidentally, the ratio of the aromatic vinyl monomer units in the polymer usually coincides with the ratio of the aromatic vinyl block regions in the polymer.

－Other areas－
Other regions contain aliphatic conjugated diene monomer units as repeating units, optionally repeating units other than aliphatic conjugated diene monomer units and aromatic vinyl monomer units (hereinafter referred to as "other repeating It may be abbreviated as "unit".).
Here, one other region may be composed of one type of other repeating unit, or may be composed of a plurality of types of other repeating units.
In addition, one other region may contain a coupling site (that is, other repeating units constituting one other region may be connected via a coupling site). .
Furthermore, other regions may have a graft portion and/or a crosslinked structure.
When the polymer has a plurality of other regions, the types and proportions of the other repeating units constituting the plurality of other regions may be the same or different.

Examples of other repeating units other than the aliphatic conjugated diene monomer unit, which constitute the other region of the polymer, include, but are not particularly limited to, alkylene structural units.

Examples of aliphatic conjugated diene monomers capable of forming aliphatic conjugated diene monomer units include 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3 -C4 or more conjugated diene compounds such as pentadiene. These can be used individually by 1 type or in combination of 2 or more types. Among these, 1,3-butadiene and isoprene are preferable from the viewpoint of further improving the adhesiveness of the negative electrode.

Further, the alkylene structural unit is a repeating unit composed only of an alkylene structure represented by the general formula: -C _n H _2n - [where n is an integer of 2 or more].
Here, the alkylene structural unit may be linear or branched, but the alkylene structural unit is preferably linear, that is, a linear alkylene structural unit. Also, the number of carbon atoms in the alkylene structural unit is preferably 4 or more (that is, n in the above general formula is an integer of 4 or more).

The method of introducing the alkylene structural unit into the polymer is not particularly limited. For example, by hydrogenating a block polymer containing a block region composed of an aromatic vinyl monomer unit and another region containing an aliphatic conjugated diene monomer unit, the aliphatic conjugated diene monomer unit is converted to an alkylene structural unit to obtain a polymer.

Furthermore, other repeating units that constitute the other region are not particularly limited, but for example, it is possible to form a secondary battery with high low-temperature charge acceptance by further improving the electrolyte solution injection property into the negative electrode. From the viewpoint of doing so, it preferably contains structural units formed by cross-linking aliphatic conjugated diene monomer units. That is, the polymer forming the particulate polymer crosslinks a block polymer containing a block region composed of aromatic vinyl monomer units and other regions containing aliphatic conjugated diene monomer units. It is preferably a polymer that

The structural unit obtained by cross-linking the aliphatic conjugated diene monomer unit is a block containing a block region composed of the aromatic vinyl monomer unit and another region containing the aliphatic conjugated diene monomer unit. It can be introduced into the polymer by cross-linking the polymer.
Here, the cross-linking is not particularly limited, and can be performed using a radical initiator such as a redox initiator obtained by combining an oxidizing agent and a reducing agent. Examples of oxidizing agents include diisopropylbenzene hydroperoxide, cumene hydroperoxide, t-butyl hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, di-t-butyl peroxide, Organic peroxides such as isobutyryl peroxide and benzoyl peroxide can be used. As the reducing agent, compounds containing metal ions in a reduced state such as ferrous sulfate and cuprous naphthenate; sulfonic acid compounds such as sodium methanesulfonate; amine compounds such as dimethylaniline; be able to. These organic peroxides and reducing agents may be used alone or in combination of two or more.
The cross-linking may be carried out in the presence of a cross-linking agent such as a polyvinyl compound such as divinylbenzene; a polyallyl compound such as diallyl phthalate, triallyl trimellitate or diethylene glycol bisallyl carbonate; various glycols such as ethylene glycol diacrylate; good. Moreover, cross-linking can also be performed using irradiation of active energy rays such as γ-rays.

Here, the total amount of the aliphatic conjugated diene monomer unit, the structural unit formed by crosslinking the aliphatic conjugated diene monomer unit, and the alkylene structural unit in the polymer forming the particulate polymer is When the amount of all repeating units is 100% by mass, it is preferably 50% by mass or more, more preferably 65% by mass or more, preferably 98% by mass or less, and 95% by mass or less is more preferable. Then, in a block polymer (hydrogenated and/or crosslinked block polymer) containing a block region composed of aromatic vinyl monomer units and other regions containing aliphatic conjugated diene monomer units The ratio of aliphatic conjugated diene monomer units is preferably 50% by mass or more, more preferably 65% by mass or more, when the amount of all repeating units in the block polymer is 100% by mass. It is preferably 98% by mass or less, more preferably 95% by mass or less.
If the ratio of the aliphatic conjugated diene monomer unit, the structural unit formed by cross-linking the aliphatic conjugated diene monomer unit, and the alkylene structural unit in the polymer is 50% by mass or more, the adhesion of the negative electrode is improved. can be made On the other hand, if the ratio of the aliphatic conjugated diene monomer unit, the structural unit formed by crosslinking the aliphatic conjugated diene monomer unit, and the alkylene structural unit in the polymer is 98% by mass or less, the flexibility of the polymer The pressability of the negative electrode can be further improved by ensuring the properties, and the tackiness development of the polymer can be sufficiently suppressed.

Other regions of the polymer may contain repeating units other than aliphatic conjugated diene monomer units, structural units obtained by bridging aliphatic conjugated diene monomer units, and alkylene structural units. Specifically, other regions of the polymer include acidic group-containing monomer units such as carboxyl group-containing monomer units, sulfonic acid group-containing monomer units, and phosphoric acid group-containing monomer units; acrylonitrile units; and nitrile group-containing monomer units such as methacrylonitrile units; and (meth) acrylic acid ester monomer units such as acrylic acid alkyl ester units and methacrylic acid alkyl ester units; may contain. Here, in the present invention, "(meth)acrylic acid" means acrylic acid and/or methacrylic acid.

Among them, from the viewpoint of improving the viscosity stability of the slurry composition by making the surface acid amount of the particulate polymer an appropriate size, the other region of the polymer preferably contains an acidic group-containing monomer unit. .
In addition, the acidic group which the acidic group-containing monomer unit has may form a salt with an alkali metal, ammonia, or the like.

Examples of carboxyl group-containing monomers capable of forming carboxyl group-containing monomer units include monocarboxylic acids and derivatives thereof, dicarboxylic acids and acid anhydrides thereof, and derivatives thereof.
Monocarboxylic acids include acrylic acid, methacrylic acid, crotonic acid and the like.
Monocarboxylic acid derivatives include 2-ethylacrylic acid, isocrotonic acid, α-acetoxyacrylic acid, β-trans-aryloxyacrylic acid, α-chloro-β-E-methoxyacrylic acid and the like.
Dicarboxylic acids include maleic acid, fumaric acid, itaconic acid, and the like.
Dicarboxylic acid derivatives include methylmaleic acid, dimethylmaleic acid, phenylmaleic acid, chloromaleic acid, dichloromaleic acid, fluoromaleic acid, butyl maleate, nonyl maleate, decyl maleate, dodecyl maleate, and octadecyl maleate. and maleic acid monoesters such as fluoroalkyl maleate.
Acid anhydrides of dicarboxylic acids include maleic anhydride, acrylic anhydride, methyl maleic anhydride, dimethyl maleic anhydride, and citraconic anhydride.
As the carboxyl group-containing monomer, an acid anhydride that produces a carboxyl group by hydrolysis can also be used.
Furthermore, the carboxyl group-containing monomers include ethylenically unsaturated polycarboxylic acids such as butenetricarboxylic acid, and partial esters of ethylenically unsaturated polycarboxylic acids such as monobutyl fumarate and mono-2-hydroxypropyl maleate. etc. can also be used.

Examples of sulfonic acid group-containing monomers capable of forming sulfonic acid group-containing monomer units include styrenesulfonic acid, vinylsulfonic acid (ethylenesulfonic acid), methylvinylsulfonic acid, and (meth)allylsulfonic acid. , 3-allyloxy-2-hydroxypropanesulfonic acid.
In the present invention, "(meth)allyl" means allyl and/or methallyl.

Furthermore, the phosphate group-containing monomer capable of forming the phosphate group-containing monomer unit includes, for example, 2-(meth)acryloyloxyethyl phosphate, methyl-2-(meth)acryloyloxyethyl phosphate, , ethyl phosphate-(meth)acryloyloxyethyl.
In addition, in this invention, "(meth)acryloyl" means acryloyl and/or methacryloyl.

Here, the monomers described above may be used singly or in combination of two or more. As the acidic group-containing monomer capable of forming the acidic group-containing monomer unit, methacrylic acid, itaconic acid and acrylic acid are preferable, and methacrylic acid is more preferable.

When the polymer has an acidic group-containing monomer unit, the ratio of the acidic group-containing monomer unit in the polymer is 0 when the amount of all repeating units in the polymer is 100% by mass. It is preferably 1% by mass or more, more preferably 0.5% by mass or more, still more preferably 1% by mass or more, preferably 20% by mass or less, and 18% by mass or less. It is more preferable that the content is 15% by mass or less.

Other monomer units such as the above-mentioned acidic group-containing monomer units, nitrile group-containing monomer units, and (meth)acrylic acid ester monomer units are not particularly limited, and are graft polymerized. can be introduced into the polymer using any polymerization method such as When another monomer unit is introduced by graft polymerization, the polymer will contain a graft portion, and will have a structure in which the polymer serving as the graft portion is bound to the polymer serving as the trunk portion. Become.

Here, the graft polymerization is not particularly limited, and can be performed using a known graft polymerization method. Specifically, graft polymerization can be performed using a radical initiator such as a redox initiator formed by combining an oxidizing agent and a reducing agent. As the oxidizing agent and reducing agent, those that can be used for cross-linking a block polymer containing a block region composed of aromatic vinyl monomer units and other regions containing aliphatic conjugated diene monomer units. The same oxidizing agent and reducing agent as described above can be used.
Then, when graft polymerization is performed using a redox initiator on a block polymer containing a block region composed of an aromatic vinyl monomer unit and another region containing an aliphatic conjugated diene monomer unit, can simultaneously proceed with the introduction of other monomer units by graft polymerization and the cross-linking of the aliphatic conjugated diene monomer units. The graft polymerization and the cross-linking may not proceed at the same time, and only the graft polymerization may proceed by adjusting the type of radical initiator and the reaction conditions.

The particulate polymer made of the above-mentioned polymer is obtained, for example, by block-polymerizing monomers such as the above-mentioned aromatic vinyl monomer and aliphatic conjugated diene monomer in an organic solvent to form an aromatic vinyl block region. a step of obtaining a block polymer solution (block polymer solution preparation step); and a step of adding water to the obtained block polymer solution to emulsify the block polymer into particles (emulsifying step). and a step (grafting step) of obtaining an aqueous dispersion of a particulate polymer composed of a predetermined polymer by subjecting the granulated block polymer to graft polymerization. In addition, in the preparation of the particulate polymer, the grafting step may be performed before the emulsifying step.

- Block polymer solution preparation step -
The block polymerization method in the block polymer solution preparation step is not particularly limited. For example, polymerization is performed by adding a second monomer component different from the first monomer component to the solution obtained by polymerizing the first monomer component, and if necessary, A block polymer can be prepared by further repeating the addition and polymerization. The organic solvent used as the reaction solvent is also not particularly limited, and can be appropriately selected according to the type of the monomer and the like.
Here, it is preferable to subject the block polymer obtained by block polymerization as described above to a coupling reaction using a coupling agent prior to the emulsification step described later. If a coupling reaction is performed, for example, the ends of diblock structures contained in the block polymer can be combined with a coupling agent to convert to a triblock structure (that is, the amount of diblocks can be reduced can do).

The coupling agent that can be used in the coupling reaction is not particularly limited, and examples thereof include a bifunctional coupling agent, a trifunctional coupling agent, a tetrafunctional coupling agent, and a pentafunctional or higher coupling agent. mentioned.
Bifunctional coupling agents include, for example, bifunctional halogenated silanes such as dichlorosilane, monomethyldichlorosilane, and dichlorodimethylsilane; dichloroethane, dibromoethane, methylene chloride, dibromomethane, and other bifunctional halogenated alkanes; , monomethyldichlorotin, dimethyldichlorotin, monoethyldichlorotin, diethyldichlorotin, monobutyldichlorotin, dibutyldichlorotin, and other bifunctional tin halides;
Examples of trifunctional coupling agents include trifunctional halogenated alkanes such as trichloroethane and trichloropropane; trifunctional halogenated silanes such as methyltrichlorosilane and ethyltrichlorosilane; methyltrimethoxysilane and phenyltrimethoxysilane; trifunctional alkoxysilanes such as phenyltriethoxysilane;
Examples of the tetrafunctional coupling agent include tetrafunctional halogenated alkanes such as carbon tetrachloride, carbon tetrabromide and tetrachloroethane; tetrafunctional halogenated silanes such as tetrachlorosilane and tetrabromosilane; tetramethoxysilane; Tetrafunctional alkoxysilanes such as tetraethoxysilane; Tetrafunctional tin halides such as tetrachlorotin and tetrabromotin;
Penta- or higher-functional coupling agents include, for example, 1,1,1,2,2-pentachloroethane, perchloroethane, pentachlorobenzene, perchlorobenzene, octabromodiphenyl ether and decabromodiphenyl ether.
These can be used individually by 1 type or in combination of 2 or more types.

Among those mentioned above, dichlorodimethylsilane is preferable as the coupling agent. According to a coupling reaction using a coupling agent, a coupling site derived from the coupling agent is introduced into a polymer chain (for example, a triblock structure) that constitutes a block polymer.

The solution of the block polymer obtained after the above-described block polymerization and optionally the coupling reaction may be directly subjected to the emulsification step described later, but if necessary, the above-described hydrogenation of the block polymer may be performed. After performing, it can also be subjected to an emulsification step.

- Emulsification process -
The emulsification method in the emulsification step is not particularly limited, but for example, a method of phase inversion emulsification of a preliminary mixture of the block polymer solution obtained in the block polymer solution preparation step described above and an emulsifier aqueous solution is preferred. Here, for phase inversion emulsification, for example, known emulsifiers and emulsifying dispersers can be used. Specifically, the emulsifying and dispersing machine is not particularly limited. (manufactured by Tokushu Kika Kogyo Co., Ltd.), etc.; trade name "TK Pipeline Homomixer" (manufactured by Tokushu Kika Kogyo Co., Ltd.), trade name "Colloid Mill" (manufactured by Shinko Pantec Co., Ltd.), trade name "Slasher" (manufactured by Nippon Coke Kogyo Co., Ltd.), trade name "Trigonal wet pulverizer" (manufactured by Mitsui Miike Kakoki Co., Ltd.), trade name "Cavitron" (manufactured by Eurotech), trade name "Milder" (Taiheiyo Kiko Co., Ltd.) ), trade name "Fine Flow Mill" (manufactured by Taiheiyo Kiko Co., Ltd.), etc.; trade name "Microfluidizer" (manufactured by Mizuho Kogyo Co., Ltd.), trade name "Nanomizer" High-pressure emulsifying and dispersing machine such as "APV Gaulin" (manufactured by Gaulin); Membrane emulsifying and dispersing machine such as "Membrane Emulsifier" (manufactured by Reika Kogyo); ) and the like; and an ultrasonic emulsifier and disperser such as the trade name “Ultrasonic Homogenizer” (manufactured by Branson). The conditions for the emulsification operation using the emulsifying disperser (eg, treatment temperature, treatment time, etc.) are not particularly limited, and may be appropriately selected so as to achieve a desired dispersed state.
Then, from the emulsified liquid obtained after the phase inversion emulsification, if necessary, the organic solvent is removed by a known method or the like, so that an aqueous dispersion of the block polymer formed into particles can be obtained.

-Grafting process-
The method of graft polymerization in the grafting step is not particularly limited. For example, in the presence of a monomer to be graft-polymerized, a radical initiator such as a redox initiator is used to allow graft polymerization and cross-linking of the block polymer to proceed simultaneously. A method is preferred. Here, the reaction conditions can be adjusted according to the composition of the block polymer and the like.

<<particulate binder>>
The slurry composition of the present invention contains, as a binder, in addition to the particulate polymer, a particulate binder that is a polymer having a composition and/or properties different from those of the particulate polymer. Also good. Such a particulate binder is not particularly limited as long as the binder as a whole satisfies the above-described specific properties (contact angle and swelling degree with respect to the electrolytic solution). Known particulate binders such as coalescing can be used. Among them, a styrene-butadiene random copolymer is preferable from the viewpoint of binding properties. The styrene-butadiene random copolymer contains 20% by mass or more and 80% by mass or less of styrene monomer units, and 20% by mass or more and 80% by mass or less of butadiene monomer units, and optionally a hydrophilic group. You may contain the monomer unit which has 1 mass % or more and 15 mass % or less. In addition, the "hydrophilic group" includes the same hydrophilic group as the hydrophilic group that the water-soluble polymer described later may have. Among them, monomer units having a carboxyl group and monomer units having a hydroxyl group are preferable as the monomer units having a hydrophilic group. As the particulate binder, a polymer prepared according to a standard method such as an emulsion polymerization method may be used, or a marketed product may be used.

[Swelling degree of particulate binder]
The particulate binder has a degree of swelling of 110% or more and 450 with respect to an electrolytic solution (an electrolytic solution containing LiPF ₆ with a concentration of 1 mol/L and a mixed solvent in which the volume ratio of ethylene carbonate and ethyl methyl carbonate is 3:7). % or less. If the degree of swelling of the particulate binder with respect to the electrolytic solution is at least the above lower limit, the particulate binder moderately swells with respect to the electrolytic solution, and ions that contribute to the battery reaction inside the secondary battery. becomes easier to move, and it is possible to more effectively suppress the internal resistance of the secondary battery from becoming excessively high. Further, if the degree of swelling of the particulate binder with respect to the electrolytic solution is equal to or less than the above upper limit, the electrolytic solution easily moves in the negative electrode mixture layer, and the deposition of lithium ions and the like is more effectively suppressed. can do. Furthermore, when the degree of swelling of the particulate binder with respect to the electrolytic solution is equal to or less than the above upper limit, the low temperature of the obtained secondary battery is associated with the ease of movement of the electrolytic solution in the negative electrode mixture layer. Charge acceptance can be enhanced.

<<Mixing ratio of particulate polymer and particulate binder>>
The mixing ratio of the particulate polymer and the particulate binder in the binder is preferably particulate polymer:particulate binder=10:0 to 2:8 on a mass basis, and 10: A ratio of 0 to 3:7 is more preferred, and a ratio of 10:0 to 4:6 is even more preferred. If the occupancy of the particulate polymer is 20% by mass or more of the entire binder, the mobility of the electrolyte in the negative electrode mixture layer can be increased, and a negative electrode with even better electrolyte pourability can be formed. can do.

<Negative electrode active material>
The negative electrode active material is not particularly limited, and known negative electrode active materials used in secondary batteries can be used. Specifically, for example, the negative electrode active material that can be used in the negative electrode mixture layer of a lithium ion secondary battery as an example of a secondary battery is not particularly limited, and the following negative electrode active materials can be used. can.

Examples of the negative electrode active material to be mixed in the negative electrode mixture layer of the negative electrode of the lithium ion secondary battery include carbon-based negative electrode active materials, metal-based negative electrode active materials, and negative electrode active materials in which these are combined.
Here, the carbon-based negative electrode active material refers to an active material having carbon as a main skeleton and into which lithium can be inserted (also referred to as “doping”). And, as the carbon-based negative electrode active material, specifically, coke, mesocarbon microbeads (MCMB), mesophase pitch-based carbon fiber, pyrolytic vapor growth carbon fiber, phenol resin baked body, polyacrylonitrile-based carbon fiber, Examples include carbonaceous materials such as pseudoisotropic carbon, furfuryl alcohol resin sintered body (PFA) and hard carbon, and graphite materials such as natural graphite and artificial graphite.
In addition, the metal-based negative electrode active material is an active material containing a metal, and usually contains an element capable of intercalating lithium in its structure, and the theoretical electric capacity per unit mass when lithium is intercalated is 500 mAh / g or more. As the metal-based active material, for example, lithium metal, a single metal capable of forming a lithium alloy (eg, Ag, Al, Ba, Bi, Cu, Ga, Ge, In, Ni, P, Pb, Sb, Si , Sn, Sr, Zn, Ti, etc.) and their oxides, sulfides, nitrides, silicides, carbides and phosphides. Furthermore, oxides such as lithium titanate can be mentioned.
In addition, the negative electrode active material mentioned above may be used individually by 1 type, and may be used in combination of 2 or more types.

The tap density of the negative electrode active material is preferably 0.70 g/cm ³ or more, more preferably 0.75 g/cm ³ or more, and even more preferably 0.80 g/cm ³ or more. , is preferably 1.10 g/cm ³ or less, more preferably 1.05 g/cm ³ or less, and even more preferably 1.00 g/cm ³ or less. If the tap density of the negative electrode active material is equal to or higher than the above lower limit, the flow of the negative electrode active material contained in the negative electrode mixture layer is suppressed, and the electrolyte solution is formed such that the negative electrode active material is oriented in the negative electrode mixture layer. A good flow path can be maintained. Further, when the tap density of the negative electrode active material is equal to or less than the above upper limit, springback is suppressed when the negative electrode is pressed to increase the density, and a high-density negative electrode can be formed satisfactorily.

The mixing ratio of the particulate polymer and the negative electrode active material in the slurry composition is not particularly limited. For example, the amount of the particulate polymer to be blended can be such that the amount of the particulate polymer is 0.5 parts by mass or more and 15 parts by mass or less in terms of solid content per 100 parts by mass of the negative electrode active material.

<Thickening component>
The viscosity-increasing component is a component that imparts viscosity to the slurry composition and can disperse well the above-mentioned particulate polymer and other compounding components in the slurry composition. The thickening component is not particularly limited as long as it can exhibit such functions, and known thickening agents, water-soluble polymers, and the like can be mentioned. Among them, by blending a water-soluble polymer as a viscosity-increasing component, the structure of the negative electrode mixture layer formed using the slurry composition is optimized, and the electrolyte pourability of the negative electrode can be further enhanced. In addition, the fact that the polymer is “water-soluble” means that when 0.5 g of the polymer is dissolved in 100 g of water at a temperature of 25° C., the insoluble content is less than 1.0% by mass.

The water-soluble polymer may be in the form of a salt (water-soluble polymer salt). That is, in the present invention, the "water-soluble polymer" also includes salts of the water-soluble polymer. Suitable water-soluble polymers include, for example, water-soluble polymers having a hydrophilic group and having a weight average molecular weight of 15,000 or more and 3,000,000 or less.

[Hydrophilic group]
Hydrophilic groups that the water-soluble polymer may have include, for example, carboxyl groups, sulfonic acid groups, phosphoric acid groups, and hydroxyl groups. The water-soluble polymer may have only one type of these hydrophilic groups, or may have two or more types. Among these, from the viewpoint of improving the coating density by increasing the stability of the slurry composition, suppressing aggregation of the particulate polymer or the like during coating of the slurry composition, and further improving the handling property of the electrode As the hydrophilic group, a carboxyl group and a sulfonic acid group are preferable, and a carboxyl group is more preferable.

Here, the method for introducing a hydrophilic group into the water-soluble polymer is not particularly limited, and a polymer is prepared by addition polymerization of the above-mentioned monomer containing a hydrophilic group (hydrophilic group-containing monomer). However, a water-soluble polymer containing a hydrophilic group-containing monomer unit may be obtained, or an arbitrary polymer may be modified (for example, terminal modification) to obtain a water-soluble polymer having the hydrophilic group described above. may be obtained, but the former is preferred.

- Hydrophilic group-containing monomer unit -
The water-soluble polymer enhances the stability of the slurry composition, improves the coating density, suppresses aggregation of the particulate polymer and the like during application of the slurry composition, and further improves the handling properties of the negative electrode. From the viewpoint of improving the It preferably contains at least one selected from the group consisting of, more preferably contains at least one of a carboxyl group-containing monomer unit and a sulfonic acid group-containing monomer unit, a carboxyl group-containing monomer unit It is further preferred to contain The water-soluble polymer may contain only one type of hydrophilic group-containing monomer unit described above, or may contain two or more types.

Here, a carboxyl group-containing monomer capable of forming a carboxyl group-containing monomer unit, a sulfonic acid group-containing monomer capable of forming a sulfonic acid group-containing monomer unit, and a phosphoric acid group-containing monomer As the phosphate group-containing monomer capable of forming units, for example, the same monomers as those usable for the polymer forming the particulate polymer can be used.

Examples of hydroxyl group-containing monomers capable of forming hydroxyl group-containing monomer units include ethylenically unsaturated alcohols such as (meth)allyl alcohol, 3-buten-1-ol, and 5-hexene-1-ol; 2-hydroxyethyl acid, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, di-2-hydroxyethyl maleate, di-4-hydroxybutyl maleate, itacon ^alkanol _esters of _{ethylenically unsaturated} carboxylic acids such as di- ₂ -hydroxypropyl acid; , q is an integer of 2 to 4, R ^a represents a hydrogen atom or a methyl group) esters of polyalkylene glycol and (meth)acrylic acid; 2-hydroxyethyl-2′-(meth ) Acryloyloxyphthalate, 2-hydroxyethyl-2′-(meth)acryloyloxysuccinate, and other dihydroxy esters of dicarboxylic acid mono (meth) acrylic acid esters; 2-hydroxyethyl vinyl ether, 2-hydroxypropyl vinyl ether, etc. Vinyl ethers; (meth)allyl-2-hydroxyethyl ether, (meth)allyl-2-hydroxypropyl ether, (meth)allyl-3-hydroxypropyl ether, (meth)allyl-2-hydroxybutyl ether, (meth)allyl Alkylene glycol mono(meth)allyl ethers such as -3-hydroxybutyl ether, (meth)allyl-4-hydroxybutyl ether, (meth)allyl-6-hydroxyhexyl ether; diethylene glycol mono(meth)allyl ether, dipropylene glycol Polyoxyalkylene glycol mono(meth)allyl ethers such as mono(meth)allyl ether; glycerin mono(meth)allyl ether, (meth)allyl-2-chloro-3-hydroxypropyl ether, (meth)allyl-2- Mono(meth)allyl ethers of halogen- and hydroxy-substituted (poly)alkylene glycols such as hydroxy-3-chloropropyl ether; Mono(meth)allyl ethers of polyhydric phenols such as eugenol and isoeugenol and halogen-substituted products thereof ; (meth) allyl-2-hydroxyethyl thioether, (meth) allyl-2-hydroxy (Meth)allylthioethers of alkylene glycol such as propylthioether; hydroxyl groups such as N-hydroxymethylacrylamide (N-methylolacrylamide), N-hydroxymethylmethacrylamide, N-hydroxyethylacrylamide, N-hydroxyethylmethacrylamide and the like having amides.

The ratio of hydrophilic group-containing monomer units in the water-soluble polymer is preferably 10% by mass or more when the amount of all repeating units in the water-soluble polymer is 100% by mass. If the ratio of the hydrophilic group-containing monomer unit in the water-soluble polymer is 10% by mass or more, the stability of the slurry composition is increased and the coating density is improved, and the slurry composition is applied in a particulate form when applied. Aggregation of polymers and the like can be suppressed. The upper limit of the ratio of hydrophilic group-containing monomer units in the water-soluble polymer is not particularly limited, and can be 100% by mass or less.

-Other monomeric units-
The water-soluble polymer may contain monomer units (other monomer units) other than the hydrophilic group-containing monomer units described above. Other monomers that can form other monomer units contained in the water-soluble polymer are not particularly limited as long as they are copolymerizable with the hydrophilic group-containing monomer described above. Other monomers include, for example, (meth)acrylic acid ester monomers, fluorine-containing (meth)acrylic acid ester monomers, and crosslinkable monomers.
As the (meth)acrylic acid ester monomer, the fluorine-containing (meth)acrylic acid ester monomer, and the crosslinkable monomer, for example, those exemplified in JP-A-2015-70245 can be used.
In addition, another monomer may be used individually by 1 type, and may be used in combination of 2 or more types.

[Method for preparing water-soluble polymer]
The water-soluble polymer can be produced by polymerizing a monomer composition containing the monomers described above in an aqueous solvent such as water. At this time, the content ratio of each monomer in the monomer composition can be determined according to the content ratio of each monomer unit in the water-soluble polymer.
The polymerization mode is not particularly limited, and any method such as a solution polymerization method, a suspension polymerization method, a bulk polymerization method, and an emulsion polymerization method can be used. As the polymerization reaction, any reaction such as ionic polymerization, radical polymerization, and living radical polymerization can be used.
Additives such as emulsifiers, dispersants, polymerization initiators, polymerization aids and molecular weight modifiers used in the polymerization may be commonly used ones. The amount of these additives used can also be the amount generally used. Polymerization conditions can be appropriately adjusted according to the polymerization method, the type of polymerization initiator, and the like.

[Content ratio of binder and water-soluble polymer]
The content ratio (in terms of solid content) of the binder and the water-soluble polymer in the slurry composition of the present invention is not particularly limited. It is preferably 50% by mass or more and 99.8% by mass or less of the total content (100% by mass).

<Aqueous medium>
The aqueous medium contained in the slurry composition of the present invention is not particularly limited as long as it contains water, and may be an aqueous solution or a mixed solution of water and a small amount of an organic solvent.

<Other ingredients>
The slurry composition of the present invention can contain components (other components) other than the above components. For example, the slurry composition may contain known additives. Such known additives include, for example, antioxidants such as 2,6-di-tert-butyl-p-cresol, antifoaming agents, and dispersants (excluding those corresponding to the viscosity-increasing components described above). ), and conductive materials. In addition, other components may be used individually by 1 type, and may be used in combination of 2 or more types by arbitrary ratios.

<Method for preparing slurry composition>
The slurry composition of the present invention is not particularly limited, and the particulate polymer, the negative electrode active material, and the optionally used water-soluble polymer and/or other components are mixed in an aqueous medium. A slurry composition can be prepared by mixing in the presence. Moreover, the mixing method is not particularly limited, but mixing can be performed using a commonly used stirrer or disperser.

(Non-aqueous secondary battery negative electrode)
The electrode for a non-aqueous secondary battery of the present invention includes a negative electrode mixture layer formed using the slurry composition for a non-aqueous secondary battery negative electrode described above. Therefore, the negative electrode mixture layer is made of the dried slurry composition described above, and usually contains a negative electrode active material and a component derived from a particulate polymer, and optionally a water-soluble polymer and other components. contains In addition, each component contained in the negative electrode mixture layer was contained in the slurry composition for the non-aqueous secondary battery negative electrode, and the preferred abundance ratio of each component is the slurry composition is the same as the preferred abundance ratio of each component in the In addition, although the particulate polymer exists in the form of particles in the slurry composition, it may be in the form of particles or any other shape in the negative electrode mixture layer formed using the slurry composition. may be
The negative electrode for a non-aqueous secondary battery of the present invention uses the slurry composition for a non-aqueous secondary battery negative electrode described above to form the negative electrode mixture layer, and thus has excellent electrolyte pourability. . A secondary battery having such a negative electrode for a non-aqueous secondary battery can be charged satisfactorily when charging is performed in a low-temperature environment.

In the negative electrode for non-aqueous secondary batteries of the present invention, the density of the negative electrode mixture layer is preferably 1.60 g/cm ³ or more, more preferably 1.65 g/cm ³ or more, and 2.00 g/cm 3 or more. /cm ³ or less, more preferably 1.95 g/cm ³ or less, even more preferably 1.90 g/cm ³ or less. A secondary battery including a negative electrode in which the density of the negative electrode mixture layer is equal to or higher than the above lower limit has a high capacity. Further, a secondary battery including a negative electrode in which the density of the negative electrode mixture layer is equal to or less than the above upper limit value is highly convenient because it can be charged and discharged by normal charging and discharging operations.

<Production of negative electrode for non-aqueous secondary battery>
Here, the negative electrode mixture layer of the negative electrode for non-aqueous secondary batteries of the present invention can be formed, for example, using the following method.
1) A method of applying the slurry composition of the present invention to the surface of a current collector and then drying;
2) a method of immersing a current collector in the slurry composition of the present invention and then drying it; and 3) coating the slurry composition of the present invention on a release substrate and drying to produce a negative electrode mixture layer. and transferring the obtained negative electrode mixture layer to the surface of the current collector.
Among these methods, the method 1) is particularly preferable because the layer thickness of the negative electrode mixture layer can be easily controlled. The method 1) includes, in detail, a step of applying a slurry composition onto a current collector (application step), and drying the slurry composition applied on the current collector to form a negative electrode on the current collector. It includes a step of forming a mixture layer (drying step).

[Coating process]
The method for applying the slurry composition onto the current collector is not particularly limited, and a known method can be used. Specifically, as the coating method, a doctor blade method, a dip method, a reverse roll method, a direct roll method, a gravure method, an extrusion method, a brush coating method, or the like can be used. At this time, the slurry composition may be applied to only one side of the current collector, or may be applied to both sides. The thickness of the slurry film on the current collector after application and before drying can be appropriately set according to the thickness of the negative electrode mixture layer obtained by drying.

Here, as the current collector to which the slurry composition is applied, a material having electrical conductivity and electrochemical durability is used. Specifically, as the current collector, for example, a current collector made of iron, copper, aluminum, nickel, stainless steel, titanium, tantalum, gold, platinum, or the like can be used. In addition, one type of the above materials may be used alone, or two or more types may be used in combination at an arbitrary ratio.

[Drying process]
The method for drying the slurry composition on the current collector is not particularly limited, and known methods can be used. A drying method by irradiation can be used. By drying the slurry composition on the current collector in this manner, a negative electrode mixture layer is formed on the current collector to obtain a negative electrode for a non-aqueous secondary battery comprising the current collector and the negative electrode mixture layer. be able to.

After the drying step, the negative electrode mixture layer may be pressurized using a mold press, a roll press, or the like. The pressure treatment can improve the adhesion between the negative electrode mixture layer and the current collector, and further increase the density of the obtained negative electrode mixture layer. Moreover, when the negative electrode mixture layer contains a curable polymer, it is preferable to cure the polymer after forming the negative electrode mixture layer.

(Non-aqueous secondary battery)
The non-aqueous secondary battery of the present invention includes a positive electrode, the negative electrode for non-aqueous secondary batteries described above, an electrolytic solution, and a separator. Since the non-aqueous secondary battery of the present invention is manufactured using the negative electrode for a non-aqueous secondary battery described above, the mobility of the electrolyte inside the secondary battery is high, and the low-temperature charge acceptance is excellent.
In addition, although the case where the secondary battery is a lithium ion secondary battery will be described below as an example, the present invention is not limited to the following example.

<Positive electrode>
Here, the positive electrode for non-aqueous secondary batteries that can be used in the non-aqueous secondary battery of the present invention is not particularly limited, and known positive electrodes used in the production of secondary batteries can be used. can. Specifically, a positive electrode obtained by forming a positive electrode mixture layer on a current collector using a known manufacturing method can be used.

<Electrolyte>
As the electrolytic solution, an organic electrolytic solution in which a supporting electrolyte is dissolved in an organic solvent is usually used. Lithium salts, for example, are used as supporting electrolytes for lithium ion secondary batteries. Examples of lithium salts 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. Among them, LiPF ₆ , LiClO ₄ and CF ₃ SO ₃ Li are preferable because they are easily dissolved in a solvent and exhibit a high degree of dissociation. In addition, one electrolyte may be used alone, or two or more electrolytes may be used in combination at an arbitrary ratio. Generally, lithium ion conductivity tends to increase as a supporting electrolyte with a higher degree of dissociation is used, so the lithium ion conductivity can be adjusted depending on the type of supporting electrolyte.

The organic solvent used in the electrolytic solution is not particularly limited as long as it can dissolve the supporting electrolyte. Examples include 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, dimethyl sulfur-containing compounds such as sulfoxide; and the like are preferably used. A mixture of these solvents may also be used. Among them, carbonates are preferably used because they have a high dielectric constant and a wide stable potential region. Usually, the lower the viscosity of the solvent used, the higher the lithium ion conductivity tends to be, so the lithium ion conductivity can be adjusted by the type of solvent.
Note that the concentration of the electrolyte in the electrolytic solution can be adjusted as appropriate. Further, known additives can be added to the electrolytic solution.

<Separator>
The separator is not particularly limited, and for example, those described in JP-A-2012-204303 can be used. Among these, polyolefin-based ( A microporous membrane made of resin (polyethylene, polypropylene, polybutene, polyvinyl chloride) is preferred.

Then, in the secondary battery of the present invention, for example, the positive electrode and the negative electrode are superimposed with a separator interposed therebetween, and if necessary, they are rolled or folded according to the shape of the battery and placed in a battery container. It can be produced by injecting an electrolytic solution into the container and sealing it. Here, in the non-aqueous secondary battery of the present invention, the negative electrode for non-aqueous secondary batteries described above is used. The non-aqueous secondary battery of the present invention may optionally contain overcurrent protection elements such as fuses and PTC elements, etc., in order to prevent the occurrence of internal pressure rises, overcharge/discharge, etc. of the secondary battery. An expanded metal, a lead plate, or the like may be provided. The shape of the secondary battery may be, for example, coin-shaped, button-shaped, sheet-shaped, cylindrical, rectangular, or flat.

EXAMPLES The present invention will be specifically described below based on examples, but the present invention is not limited to these examples. In the following description, "%" and "parts" representing amounts are based on mass unless otherwise specified.
In addition, in a polymer produced by polymerizing a plurality of types of monomers, the proportion of monomer units formed by polymerizing a certain monomer in the polymer is usually as follows, unless otherwise specified. It corresponds to the ratio (feed ratio) of the certain monomer to the total monomers used for the polymerization of the polymer.
In Examples and Comparative Examples, the contact angle of the electrolyte and the degree of swelling of the electrolyte of the binder, the degree of swelling of the electrolyte of the particulate binder, the tap density of the negative electrode active material, the low-temperature charge acceptability of the secondary battery, In addition, the electrolyte pourability of the negative electrode was measured or evaluated by the following method.

<Electrolyte solution contact angle of binder>
In Examples 1 and 4 and Comparative Examples 1 and 2, the films obtained by forming the prepared aqueous dispersions of the particulate polymer were used as objects for measuring the contact angle of the electrolytic solution. Further, in Examples 2 and 3, the particulate polymer was added to the prepared aqueous dispersion of the particulate polymer so that the mixing ratio with the particulate polymer was as shown in Table 1 on the solid content mass basis. A film obtained by forming a mixture obtained by adding a binder was used as an object for measuring the contact angle of the electrolyte. The procedure for measuring the contact angle was as follows.
A contact angle meter (manufactured by Kyowa Interface Science Co., Ltd., "DMs-400") was used as a measuring device. In addition, as the electrolytic solution for measuring the contact angle of the electrolytic solution, LiPF ₆ as a supporting electrolyte was added to a mixed solvent having a volume ratio of ethylene carbonate and ethyl methyl carbonate of 3:7, and the concentration was 1 mol/L. (hereinafter also referred to as "EC: EMC=3:7; LiPF ₆ =1 mol/L" electrolytic solution) was used. Such an electrolytic solution is dropped onto the film in a dry room at 25° C. (under an environment with a dew point temperature of −40° C. or less), and the image obtained from the horizontal direction is analyzed by the contact angle meter based on the tangent line method. , the contact angle was determined. In Example 4, LiPF ₆ as a supporting electrolyte was dissolved in a mixed solvent in which the volume ratio of ethylene carbonate and diethyl carbonate was 1:2 at a concentration of 1 mol/L. Using an electrolytic solution with a composition different from the above (hereinafter also referred to as "EC: DEC = 1: 2; LiPF ₆ = 1 mol / L" electrolytic solution), the contact angle is measured according to the same procedure. did.

<Swelling degree of electrolytic solution of binder>
A film was prepared as an object for measurement of the degree of swelling of the electrolytic solution in the same manner as in the measurement of the <electrolyte solution contact angle of the binder>. As the electrolytic solution for measuring the degree of swelling of the electrolytic solution, the same "EC: EMC=3:7; LiPF ₆ =1 mol/L" electrolytic solution as in the measurement of the <electrolyte solution contact angle of the binder>, or A "EC:DEC=1:2; LiPF ₆ =1 mol/L" electrolytic solution was used.
A film to be measured was weighed to measure the pre-immersion mass M0. After that, the film was immersed in the electrolytic solution at 60° C. for 72 hours and pulled out. The electrolytic solution on the surface of the pulled up film was wiped off and weighed to obtain the post-immersion mass M1. Then, the electrolyte swelling degree (%) of the binder was calculated according to the following formula.
Swelling degree of electrolytic solution (%) = M1/M0 x 100

<Electrolytic solution swelling degree of particulate binder>
A film obtained by forming an aqueous dispersion containing a styrene-butadiene random copolymer as the particulate binder prepared in Examples 2 and 3 was used as an object for measurement of the electrolyte solution contact angle. Except for this point, the electrolytic solution swelling degree (%) of the particulate binder was calculated in the same manner as in the above <Swelling degree of electrolytic solution of binder>.

<Tap density of negative electrode active material>
The tap densities of the negative electrode active materials used in Examples and Comparative Examples were measured using a Powder Tester (registered trademark) (manufactured by Hosokawa Micron Corporation, product name “PT-D”). Specifically, first, the powder of the negative electrode active material filled in the measurement container was scraped off on the upper surface of the container. Next, a cap attached to the measuring instrument was attached to the measuring container, and the 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 the cap from a height of 1.8 cm 180 times. After the tapping was completed, the cap was removed, and the negative electrode active material powder was scraped off again on the upper surface of the container. After tapping, the ground sample was weighed and the bulk density in this state was measured as the compacted bulk density, ie tapped density (g/cm ³ ).

<Low temperature charge acceptance of secondary battery>
The lithium-ion secondary batteries prepared in Examples and Comparative Examples were allowed to stand in an environment of 25°C for 24 hours, and then charged at a constant current of 1.0C for 1 hour in an environment of 25°C. was performed, and the normal temperature charge capacity (C0) was measured. After that, the battery was discharged at a constant current of 0.1 C in an environment of 25° C., and when the voltage reached 3 V, the discharge was stopped. Next, in an environment of −15° C., charging was performed at a constant current of 1.0 C for 1 hour, and the low temperature charge capacity (C1) was measured. Then, the lithium ion acceptability in a low temperature environment (that is, the low temperature charge acceptability) X determined by C1/C0 was determined and judged according to the following criteria. It means that the larger the low-temperature charge acceptability X is, the more lithium ions can be accepted in the negative electrode mixture layer by the charging operation in a low-temperature environment.
A: Low temperature charge acceptance X is 0.5 or more and 1 or less B: Low temperature charge acceptance X is 0.4 or more and less than 0.5 C: Low temperature charge acceptance X is less than 0.4

<Electrolyte pourability of negative electrode>
The negative electrode mixture layer side of the negative electrode raw fabric produced in Examples and Comparative Examples was roll-pressed under the conditions of a linear pressure of 14 tons (tons) under an environment of a temperature of 25 ± 3 ° C., and a negative electrode mixture layer density of 1.75 g / adjusted to ^cm3 . The secondary battery negative electrode thus obtained was cut into a circle with a diameter of 16 mm, and 1 μL of propylene carbonate was dropped on the surface having the negative electrode mixture layer. The time required for the dropped droplets to permeate into the negative electrode mixture layer (hereinafter also referred to as “permeation time”) was visually measured and evaluated according to the following criteria. The permeation time is the time required from the point of dropping until the liquid is no longer found on the surface of the negative electrode mixture layer. The shorter the permeation time, the better the affinity between the electrolyte and the negative electrode even when a desired electrolyte is used instead of propylene carbonate. It shows that the liquid injection property is excellent.
A: Penetration time less than 110 seconds B: Penetration time 110 seconds or more and less than 130 seconds C: Penetration time 130 seconds or more

(Example 1)
<Preparation of particulate polymer>
[Preparation of cyclohexane solution of block polymer]
233.3 kg of cyclohexane, 54.2 mmol of N,N,N',N'-tetramethylethylenediamine (hereinafter referred to as TMEDA) and 30.0 kg of styrene were added to a pressure-resistant reactor and stirred at 40°C. 1806.5 mmol of n-butyllithium was added to the solution and polymerized for 1 hour while the temperature was raised to 50°C. The polymerization conversion of styrene was 100%. Subsequently, 70.0 kg of isoprene was continuously added to the reactor over 1 hour while controlling the temperature so as to maintain 50-60°C. Polymerization was continued for an additional hour after the isoprene addition was complete. The polymerization conversion rate of isoprene was 100%. Then, 722.6 mmol of dichlorodimethylsilane was added as a coupling agent and a coupling reaction was carried out for 2 hours to form a styrene-isoprene coupling block copolymer. Thereafter, 3612.9 mmol of methanol was added to the reaction solution in which the styrene-isoprene block copolymer having active terminals was thought to remain, and the mixture was thoroughly mixed to deactivate the active terminals. 0.3 parts of 2,6-di-tert-butyl-p-cresol was added as an antioxidant to 100 parts of the reaction solution thus obtained (containing 30.0 parts of the polymer component). The mixed solution is dropped little by little into warm water heated to 85 to 95°C to volatilize the solvent to obtain a precipitate, which is pulverized and dried with hot air at 85°C to obtain a block. A dried product containing a polymer was recovered.
Then, the recovered dried product was dissolved in cyclohexane to prepare a block polymer solution having a block polymer concentration of 15% by mass.
[Phase inversion emulsification]
Sodium alkylbenzenesulfonate was dissolved in ion-exchanged water to prepare a 5% by mass aqueous solution.
Then, 500 g of the obtained block polymer solution and 500 g of the obtained aqueous solution were charged into a tank and stirred to perform preliminary mixing. Subsequently, the preliminary mixture was transferred from the tank to a continuous high-efficiency emulsifying and dispersing machine (manufactured by Taiheiyo Kiko Co., Ltd., product name “Milder MDN303V”) at a rate of 100 g / min using a metering pump, and the rotation speed was 15000 rpm. By stirring, an emulsion obtained by phase inversion emulsification of the preliminary mixture was obtained.
Next, cyclohexane in the resulting emulsion was distilled off under reduced pressure using a rotary evaporator. After that, the evaporated emulsion was centrifuged at 7000 rpm for 10 minutes in a centrifuge (“Himac CR21N” manufactured by Hitachi Koki Co., Ltd.), and the upper layer was taken out to concentrate. Finally, the upper layer portion was filtered through a wire mesh of 100 mesh to obtain an aqueous dispersion (block polymer latex) containing particulate block polymer.
[Graft polymerization and cross-linking]
The obtained block polymer latex was diluted by adding 850 parts of distilled water to 100 parts in terms of solid content. Then, the diluted block polymer latex was charged into a nitrogen-purged polymerization reactor equipped with a stirrer and heated to 30° C. while stirring.
In another container, 6 parts of methacrylic acid as an acidic group-containing monomer and 15 parts of distilled water were mixed to prepare a diluted methacrylic acid solution. This methacrylic acid diluted solution was added over 30 minutes into the polymerization reaction vessel heated to 30°C.
Further, using another container, a solution containing 7 parts of distilled water and 0.01 part of ferrous sulfate (manufactured by Chubu Kirest Co., Ltd., trade name "Frost Fe") as a reducing agent was prepared. After adding the obtained solution into the polymerization reaction vessel, 0.5 part of 1,1,3,3-tetramethylbutyl hydroperoxide (manufactured by NOF Corporation, trade name "Perocta H") as an oxidizing agent was added. After addition and reaction at 30° C. for 1 hour, reaction was further performed at 70° C. for 2 hours. Incidentally, the polymerization conversion rate was 99%.
Then, an aqueous dispersion of a particulate polymer comprising a polymer obtained by graft-polymerizing and cross-linking the block polymer was obtained. The resulting aqueous dispersion was magnified and observed with a scanning electron microscope (SEM) to confirm that the contained polymer was in the form of particles.
Using the obtained aqueous dispersion of the particulate polymer, the contact angle of the binder with the electrolytic solution and the degree of swelling of the electrolytic solution were measured. Table 1 shows the results.
<Preparation of slurry composition for non-aqueous secondary battery negative electrode>
In a planetary mixer with a disper, 100 parts of artificial graphite (capacity: 360 mAh / g) as a negative electrode active material, 1 part of carbon black (manufactured by TIMCAL, product name "Super C65") as a conductive material, and a water-soluble polymer A 2% aqueous solution of carboxymethyl cellulose (manufactured by Nippon Paper Chemicals Co., Ltd., product name "MAC-350HC") as a solid content was added by 1.2 parts to obtain a mixture. The obtained mixture was adjusted to a solid content concentration of 60% with ion-exchanged water, and then mixed at 25° C. for 60 minutes. Next, after adjusting the solid content concentration to 52% with ion-exchanged water, the mixture was further mixed at 25° C. for 15 minutes to obtain a mixed liquid. To the resulting mixed solution, 2.0 parts of the aqueous dispersion of the particulate polymer prepared above in terms of solid content and ion-exchanged water were added to adjust the final solid content concentration to 48%. did. After further mixing for 10 minutes, defoaming treatment was performed under reduced pressure to obtain a negative electrode slurry composition.
<Formation of Negative Electrode>
The obtained negative electrode slurry composition was applied to a 15 μm-thick copper foil as a current collector with a comma coater so that the weight after drying was 11 mg/cm ² , and dried. This drying was carried out by conveying the copper foil at a speed of 0.5 m/min in an oven at 60° C. for 2 minutes. After that, heat treatment was performed at 120° C. for 2 minutes to obtain a negative electrode original fabric.
Then, the raw negative electrode was rolled by a roll press to obtain a negative electrode having a negative electrode mixture layer with a density of 1.70 g/cm ³ .
<Formation of positive electrode>
100 parts of LiCoO ₂ having a volume average particle diameter of 12 μm as a positive electrode active material, 2 parts of acetylene black (manufactured by Denki Kagaku Kogyo Co., Ltd., product name “HS-100”) as a conductive material, and polyfluoride as a binder. 2 parts of vinylidene chloride (manufactured by Kureha Co., Ltd., product name "#7208") was mixed with N-methylpyrrolidone as a solvent to adjust the total solid concentration to 70%. These were mixed by a planetary mixer to obtain a positive electrode slurry composition.
The positive electrode slurry composition thus obtained was applied onto a 20 μm thick aluminum foil as a current collector with a comma coater so that the weight after drying would be 23 mg/cm ² and dried. This drying was carried out by conveying the aluminum foil at a speed of 0.5 m/min in an oven at 60° C. for 2 minutes. After that, heat treatment was performed at 120° C. for 2 minutes to obtain a positive electrode original fabric.
Then, the raw positive electrode sheet was rolled by a roll press to obtain a positive electrode having a positive electrode mixture layer with a density of 4.0 g/cm ³ .
<Preparation of separator>
A single-layer polypropylene separator (manufactured by Celgard, product name: "Celgard 2500") was prepared as a separator made of a separator base material.
<Production of lithium ion secondary battery>
The obtained positive electrode was cut into a rectangle of 49 cm × 5 cm and placed so that the surface on the positive electrode mixture layer side faced upward, and a separator cut into 120 cm × 5.5 cm was placed on the positive electrode mixture layer. It was arranged so as to be located on the left side in the longitudinal direction. Furthermore, the obtained negative electrode was cut into a rectangle of 50 × 5.2 cm, and placed on the separator so that the surface of the negative electrode mixture layer side faced the separator and the negative electrode was positioned on the right side in the longitudinal direction of the separator. did. Then, the obtained laminate was wound by a winding machine to obtain a wound body. This wound body is wrapped with an aluminum packaging material as a battery exterior, and an electrolytic solution for a secondary battery (solvent: ethylene carbonate / ethyl methyl carbonate = 30/70 (volume ratio), supporting electrolyte: LiPF with a concentration of 1 mol / L ₆ ) was injected so that no air remained, and the opening of the exterior of the aluminum packaging material was closed by heat sealing at 150° C. to produce a wound type lithium ion secondary battery with a capacity of 800 mAh. Then, various evaluations were performed on this lithium ion secondary battery according to the above. Table 1 shows the results.

(Example 2)
At the time of preparation of the slurry composition for the negative electrode of the non-aqueous secondary battery, a particulate binder prepared as follows was blended as a binder in addition to the particulate polymer. At this time, the addition amount was adjusted so that the mass ratio of the particulate polymer and the particulate binder in the binder was 50:50 while maintaining the total mass of the binder. . The particulate polymer and the particulate binder were previously stirred for 1 hour using a stirrer (manufactured by Shinto Kagaku Co., Ltd., product name: "Three One Motor"), and then the planetary material used for preparing the slurry composition was stirred. I put it in the Lee mixer. Various operations, measurements, and evaluations were performed in the same manner as in Example 1 except for these points. Table 1 shows the results.
<Preparation of Particulate Binder>
A reactor was charged with 150 parts of ion-exchanged water, 25 parts of an aqueous sodium dodecylbenzenesulfonate solution (10% concentration) as an emulsifier, 63 parts of styrene, 3.5 parts of itaconic acid as a monomer having a carboxyl group, and a hydroxyl group. 1 part of 2-hydroxyethyl acrylate as a monomer possessed and 0.5 part of t-dodecylmercaptan as a molecular weight modifier were added in this order. Then, after replacing the gas inside the reactor with nitrogen three times, 32.5 parts of 1,3-butadiene was added. 0.5 part of potassium persulfate as a polymerization initiator was put into a reactor maintained at 60° C. to initiate a polymerization reaction, and the polymerization reaction was continued while stirring. When the polymerization conversion reached 96%, the mixture was cooled, and 0.1 part of an aqueous hydroquinone solution (concentration: 10%) was added as a polymerization terminator to terminate the polymerization reaction. Thereafter, residual monomers were removed using a rotary evaporator at a water temperature of 60° C. to obtain an aqueous dispersion of a particulate binder (styrene-butadiene random copolymer, indicated as “SBR” in Table 1). .

(Example 3)
At the time of preparation of the slurry composition for a non-aqueous secondary battery negative electrode, a particulate binder (SBR) prepared in the same manner as in Example 2 was blended as a binder in addition to the particulate polymer. At this time, the addition amount was adjusted so that the mass ratio of the particulate polymer and the particulate binder in the binder was 30:70 while maintaining the total mass of the binder. . The particulate polymer and the particulate binder were previously stirred for 1 hour using a stirrer (manufactured by Shinto Kagaku Co., Ltd., product name: "Three One Motor"), and then the planetary material used for preparing the slurry composition was stirred. I put it in the Lee mixer. Various operations, measurements, and evaluations were performed in the same manner as in Example 1 except for these points. Table 1 shows the results.

(Example 4)
<Preparation of lithium-ion secondary battery> In a mixed solvent in which the volume ratio of ethylene carbonate and diethyl carbonate is 1:2, _LiPF6 is dissolved as a supporting electrolyte at a concentration of 1 mol/L. :DEC = 1:2; LiPF ₆ = 1 mol/L electrolyte), various operations, measurements, and evaluations were carried out in the same manner as in Example 1. Table 1 shows the results.

(Comparative example 1)
Various operations, measurements, and evaluations were carried out in the same manner as in Example 1 except that an aqueous dispersion of a particulate polymer, which is a random polymer, was obtained in the following manner during the preparation of the particulate polymer. . Table 1 shows the results.
<Preparation of particulate polymer>
A reactor was charged with 150 parts of ion-exchanged water, 25 parts of an aqueous sodium dodecylbenzenesulfonate solution (10% concentration) as an emulsifier, 25 parts of styrene as an aromatic vinyl monomer, and 15 parts of methacrylic acid as an acidic group-containing monomer. parts and 0.8 parts of t-dodecylmercaptan as a molecular weight modifier were added in this order. Then, after replacing the gas inside the reactor with nitrogen three times, 60 parts of 1,3-butadiene as an aliphatic conjugated diene monomer was added. 0.5 part of potassium persulfate as a polymerization initiator was put into a reactor maintained at 60° C. to initiate a polymerization reaction, and the polymerization reaction was continued while stirring. When the polymerization conversion reached 96%, the mixture was cooled, and 0.1 part of an aqueous hydroquinone solution (concentration: 10%) was added as a polymerization terminator to terminate the polymerization reaction. Thereafter, residual monomers were removed using a rotary evaporator at a water temperature of 60° C. to obtain an aqueous dispersion of particulate random polymer (particulate polymer).

(Comparative example 2)
Various operations, measurements, and evaluations were carried out in the same manner as in Example 1 except that an aqueous dispersion of a particulate polymer, which is a random polymer, was obtained in the following manner during the preparation of the particulate polymer. . Table 1 shows the results.
<Preparation of particulate polymer>
A reactor was charged with 150 parts of ion-exchanged water, 25 parts of an aqueous sodium dodecylbenzenesulfonate solution (10% concentration) as an emulsifier, 19 parts of styrene as an aromatic vinyl monomer, 19 parts of acrylonitrile, and 19 parts of acrylonitrile as an acidic group-containing monomer. 4 parts of methacrylic acid and 0.5 parts of t-dodecylmercaptan as a molecular weight modifier were added in this order. Then, after replacing the gas inside the reactor with nitrogen three times, 58 parts of 1,3-butadiene as an aliphatic conjugated diene monomer was added. 0.5 part of potassium persulfate as a polymerization initiator was put into a reactor maintained at 60° C. to initiate a polymerization reaction, and the polymerization reaction was continued while stirring. When the polymerization conversion reached 96%, the mixture was cooled, and 0.1 part of an aqueous hydroquinone solution (concentration: 10%) was added as a polymerization terminator to terminate the polymerization reaction. Thereafter, residual monomers were removed using a rotary evaporator at a water temperature of 60° C. to obtain an aqueous dispersion of particulate random polymer (particulate polymer).

From Table 1, non-aqueous two binders containing a binder containing a particulate polymer and having a contact angle and swelling degree with respect to the electrolytic solution within predetermined ranges, and a negative electrode active material. In Examples 1 to 4 using the slurry composition for the negative electrode of the secondary battery, it was possible to form a negative electrode having excellent electrolyte pourability, and as a result, a secondary battery having excellent low-temperature charge acceptance could be formed. I understand. On the other hand, in Comparative Example 1, in which the contact angle of the binder with respect to the electrolyte solution is more than 50°, and in Comparative Example 2, in which the degree of swelling with respect to the electrolyte solution is more than 300%, the negative electrode with sufficiently good electrolyte pourability is obtained. and a secondary battery with excellent low-temperature charge acceptability could not be formed.

ADVANTAGE OF THE INVENTION According to this invention, the slurry composition for non-aqueous secondary battery negative electrodes which can form the negative electrode for non-aqueous secondary batteries which is excellent in electrolyte injection property can be provided.
Moreover, according to the present invention, it is possible to provide a negative electrode for a non-aqueous secondary battery that is excellent in electrolyte pourability and that can improve the low-temperature charge acceptability of the resulting secondary battery.
According to the present invention, it is possible to provide a non-aqueous secondary battery that has a negative electrode for a non-aqueous secondary battery that is excellent in electrolyte pourability and that is excellent in low-temperature charge acceptance.

Claims (6)

A slurry composition for a non-aqueous secondary battery negative electrode containing a binder and a negative electrode active material,
the binder comprises a particulate polymer,
The binder has a contact angle of 50° or less with an electrolytic solution containing LiPF ₆ at a concentration of 1 mol/L and a mixed solvent of ethylene carbonate and ethyl methyl carbonate at a volume ratio of 3:7,
The degree of swelling of the binder with respect to the electrolytic solution is 110% or more and 300% or less.
Slurry composition for non-aqueous secondary battery negative electrode. The particulate polymer is a copolymer containing aromatic vinyl block regions composed of aromatic vinyl monomer units and other regions containing aliphatic conjugated diene monomer units. 2. The slurry composition for a non-aqueous secondary battery negative electrode according to 1. The slurry composition for a non-aqueous secondary battery negative electrode according to claim 1 or 2, wherein the particulate polymer further contains a coupling site. 4. The slurry composition for a non-aqueous secondary battery negative electrode according to claim 1, wherein the negative electrode active material has a tap density of 0.70 g/cm ³ or more and 1.10 g/cm ³ or less. A non-aqueous secondary battery comprising a negative electrode mixture layer having a density of 1.60 g/cm ³ or more, which is formed using the slurry composition for a non-aqueous secondary battery negative electrode according to any one of claims 1 to 4. negative electrode. having a positive electrode, a negative electrode, a separator and an electrolyte,
A nonaqueous secondary battery, wherein the negative electrode is the negative electrode for a nonaqueous secondary battery according to claim 5 .