KR20180059433A - A binder composition for a non-aqueous secondary battery electrode, a slurry composition for a non-aqueous secondary battery electrode, an electrode for a non-aqueous secondary battery, - Google Patents

Abstract

The binder composition for a nonaqueous secondary battery electrode of the present invention is a binder composition for a nonaqueous secondary battery electrode comprising a particulate polymer having a core shell structure. 1. A particulate polymer, wherein the core part comprises a first polymer containing an aliphatic conjugated diene monomer unit and an aromatic vinyl monomer unit, and the shell part comprises at least 40 mass% of a (meth) acrylic acid ester monomer unit Lt; RTI ID = 0.0 > a < / RTI > second polymer. Furthermore, the degree of swelling of the particulate polymer with respect to the electrolytic solution is 2.5 times or less.

Description

A binder composition for a non-aqueous secondary battery electrode, a slurry composition for a non-aqueous secondary battery electrode, an electrode for a non-aqueous secondary battery,

The present invention relates to a binder composition for a nonaqueous secondary battery electrode, a slurry composition for a nonaqueous secondary battery electrode, an electrode for a nonaqueous secondary battery, and a nonaqueous secondary battery.

(Hereinafter sometimes abbreviated as " secondary battery ") such as a lithium ion secondary battery has a characteristic of being small in size, light in weight, high in energy density, and capable of repeatedly charging and discharging And has been used in a wide variety of applications. BACKGROUND ART In recent years, improvement of a battery member such as an electrode has been studied for the purpose of achieving higher performance of a secondary battery.

The electrode for a secondary battery generally comprises a current collector and an electrode composite layer formed on the current collector. The electrode composite layer is formed, for example, by applying a slurry composition obtained by dispersing and / or dissolving an electrode active material and a binder composition containing a binder in a solvent onto a current collector and drying it.

In recent years, attempts have been made to improve the binder composition and the slurry composition used for forming the electrode composite layer in order to achieve a performance improvement of the rechargeable battery. For example, in recent years, in order to improve the battery characteristics of a secondary battery, various compositions have been examined for a binder used for an electrode of a secondary battery or the like. Specifically, it has been proposed to form a core-shell-type particle formed of a polymer different from the surface (shell portion) and the inside (core portion) of the particles as a binder on the electrode (see, for example, Patent Document 1). The binder described in Patent Document 1 has a core portion formed by crosslinking a copolymer containing an acrylonitrile monomer unit, a styrene monomer unit, a butadiene monomer unit, an acrylate monomer unit and the like with a suitable crosslinking agent, For example, a shell portion is formed by a copolymer including an acrylate monomer unit, a styrene monomer unit and the like. Also, as a binder capable of forming an electrode layer having high adhesion to the current collector, a binder for an electrode comprising a latex obtained by a multistage emulsion polymerization has been proposed (see, for example, Patent Document 2). The latex described in Patent Document 2 is obtained by multi-stage emulsion polymerization, and includes an aromatic vinyl monomer unit, a conjugated diene monomer unit, a (meth) acrylic acid ester monomer unit, and a cyanide vinyl monomer unit in the emulsion polymerization of the first stage And forming a polymer containing an aromatic vinyl monomer unit, a conjugated diene monomer unit, and a (meth) acrylic acid ester monomer unit in the emulsion polymerization in the other step.

Japanese Patent Application Laid-Open No. 2002-75377 Japanese Patent Application Laid-Open No. 2010-129369

However, the binder according to Patent Document 1 is excellent in binding property, but the rate characteristic of the secondary battery can not be sufficiently improved. In the case of the binder according to Patent Document 2, the electrical properties of the secondary battery such as the rate characteristic and the high-temperature cycle characteristic can not be made sufficiently high at the same time while sufficiently improving the bondability between the electrode composite layer and the current collector .

Therefore, an object of the present invention is to provide a binder composition for a non-aqueous secondary battery electrode which is excellent in binding property and capable of sufficiently increasing the electrical characteristics of the secondary battery.

Further, the present invention provides a non-aqueous secondary battery electrode slurry composition capable of forming an electrode composite material layer having excellent bondability to a current collector and capable of enhancing the electrical characteristics of the secondary battery including the electrode composite material layer .

It is another object of the present invention to provide a nonaqueous secondary battery electrode capable of enhancing the electrical characteristics of the secondary battery and a nonaqueous secondary battery having the nonaqueous secondary battery electrode.

The present inventors have conducted intensive studies for the purpose of solving the above problems. The inventors of the present invention first examined various polymers composed of various monomer units constituting a binder. As a result, since the polymer containing the aliphatic conjugated diene monomer unit and the aromatic vinyl monomer unit has a long molecular chain per monomer unit, it can improve the strength of the polymer itself and improve the binding property of the binder, It has become clear that the rate characteristic of the secondary battery can not be sufficiently improved. On the other hand, it has become clear that the polymer containing the (meth) acrylic acid ester monomer unit can improve the rate characteristics of the secondary battery, but does not sufficiently improve the binding property of the binder.

Therefore, the inventors of the present invention have conducted further studies to develop a binder having the merits of the respective polymers. As a result, it has been found that a polymer containing an aliphatic conjugated diene monomer unit and an aromatic vinyl monomer unit is used as a core part and a (meth) acrylic acid ester monomer unit In a specific ratio is made to be a shell part, the electrical properties of the secondary battery including the rate characteristic can be sufficiently enhanced, and the polymer having a core shell structure excellent in binding property can be sufficiently enhanced, thereby completing the present invention .

The binder composition for a non-aqueous secondary battery electrode according to the present invention is a binder composition for a non-aqueous secondary battery electrode comprising a particulate polymer, The particulate polymer has a core shell structure having a shell portion on the outermost layer and a core portion on the inner side of the shell portion, the core portion including a first polymer containing an aliphatic conjugated diene monomer unit and an aromatic vinyl monomer unit , And the shell portion comprises a second polymer different from the first polymer, which contains 40 mass% or more of (meth) acrylic acid ester monomer units, and the degree of swelling of the particulate polymer with respect to the electrolytic solution is 2.5 times or less . Such a binder composition is excellent in binding property and can sufficiently enhance the electrical characteristics of the secondary battery.

Here, in the present specification, "(meth) acrylic acid" means acrylic acid and / or methacrylic acid.

In the present specification, "containing (including) monomer units" means that "the polymer obtained by using the monomer contains a structural unit derived from a monomer".

The " degree of swelling of the particulate polymer with respect to the electrolytic solution " can be measured by the method described in the embodiment of the present invention.

In the binder composition for a non-aqueous secondary battery electrode of the present invention, it is preferable that the first polymer contains 25 mass% or more of an aliphatic conjugated diene monomer unit and 40 mass% or more and 75 mass% or less of an aromatic vinyl monomer unit Do. Such a binder composition is more excellent in binding property and further improves the electrical characteristics of the secondary battery.

In the binder composition for a non-aqueous secondary battery electrode of the present invention, it is preferable that the second polymer further contains 20% by mass or more and less than 60% by mass of an aromatic vinyl monomer unit. Such a binder composition is more excellent in binding property and further improves the electrical characteristics of the secondary battery.

In the binder composition for a non-aqueous secondary battery electrode of the present invention, the alkyl group or the perfluoroalkyl group bonded to the non-carbonyl oxygen atom contained in the (meth) acrylic acid ester monomer unit preferably has 3 or more carbon atoms . This is because such a binder composition can further improve the electrical characteristics of the secondary battery.

In the binder composition for a non-aqueous secondary battery electrode of the present invention, it is preferable that the second polymer further contains 0.05% by mass or more and 2% by mass or less of a crosslinkable monomer unit. This is because such a binder composition can further improve the electrical characteristics of the secondary battery.

In the binder composition for a non-aqueous secondary battery electrode of the present invention, it is preferable that the thickness of the shell portion is 0.1% or more and 30% or less with respect to the volume average particle diameter (D50) of the particulate polymer. Such a binder composition is more excellent in binding property and further improves the electrical characteristics of the secondary battery.

The " thickness of the shell part " of the particulate polymer can be determined by measuring the thickness of the shell part of 100 particulate polymers using a transmission electron microscope and calculating the arithmetic mean value. The volume average particle diameter (D50) is a particle diameter at which the cumulative volume calculated from the small diameter side is 50% in terms of the particle size distribution (volume basis) measured by laser diffraction.

Furthermore, in the binder composition for a non-aqueous secondary battery electrode of the present invention, the volume average particle diameter (D50) of the particulate polymer is preferably 50 nm or more and 1000 nm or less. Such a binder composition is more excellent in binding property and further improves the electrical characteristics of the secondary battery.

The present invention aims at solving the above problem in an advantageous manner, and the slurry composition for a non-aqueous secondary battery electrode of the present invention comprises a binder composition for an electrode active material, a water-soluble polymer, and a non-aqueous secondary battery electrode . Such a slurry composition for a non-aqueous secondary battery electrode can form an electrode composite material layer having excellent bondability to a current collector and can improve the electrical characteristics of the secondary battery including the electrode composite material layer.

The present invention further provides an electrode for a non-aqueous secondary battery comprising an electrode composite layer formed by using the above-described slurry composition for a non-aqueous secondary battery electrode . When such an electrode for a non-aqueous secondary battery is used, the electrical characteristics of the secondary battery can be enhanced.

The present invention is intended to solve the above problems advantageously, and the nonaqueous secondary battery of the present invention is characterized by including the above-described nonaqueous secondary battery electrode. Such a non-aqueous secondary battery has good electrical characteristics.

According to the present invention, it is possible to provide a binder composition for a non-aqueous secondary battery electrode which is excellent in binding property and capable of sufficiently increasing the electrical characteristics of the secondary battery.

Further, according to the present invention, it is possible to provide a non-aqueous secondary battery electrode slurry composition capable of forming an electrode composite material layer having excellent bondability to a current collector and capable of improving the electrical characteristics of the secondary battery including the electrode composite material layer .

Furthermore, according to the present invention, it is possible to provide an electrode for a non-aqueous secondary battery capable of improving the electrical characteristics of the secondary battery, and a nonaqueous secondary battery having the electrode for the nonaqueous secondary battery.

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

Here, the binder composition for a non-aqueous secondary battery electrode of the present invention is used for forming an electrode of a non-aqueous secondary battery such as a lithium ion secondary battery.

The nonaqueous secondary battery electrode slurry composition of the present invention contains the above binder composition and is used in the production of the electrode for a nonaqueous secondary battery of the present invention.

Further, the non-aqueous secondary battery electrode of the present invention is characterized by including an electrode composite layer formed by using the slurry composition for a non-aqueous secondary battery electrode of the present invention. In the non-aqueous secondary battery of the present invention, And an electrode for a non-aqueous secondary battery of the present invention is used.

(Binder composition for non-aqueous secondary battery electrode)

The binder composition for a non-aqueous secondary battery electrode of the present invention comprises a particulate polymer having a core shell structure. Such a particulate polymer includes a first polymer having a shell portion on the outermost layer and a core portion on the inner side of the shell portion, the core portion containing an aliphatic conjugated diene monomer unit and an aromatic vinyl monomer unit, wherein the shell portion is a (meth) acrylic acid ester And a second polymer which is different from the first polymer and contains at least 40 mass% of monomer units.

In the present invention, the particulate polymer of the core shell structure including the core portion including the first polymer and the shell portion including the second polymer is contained in the binder composition to improve the binding property of the binder composition, The reason why the electrical characteristics of the secondary battery formed using such a binder composition can be improved is not clear, but the following mechanisms are contemplated. First, the inventors of the present invention have found that, in the development of a binder material having both advantages of a polymer containing an aliphatic conjugated diene monomer unit and an aromatic vinyl monomer unit and a polymer containing a (meth) acrylic acid ester monomer unit, It was found out that adsorption modes for the surface were different. Specifically, since the polymer containing the aliphatic conjugated diene monomer unit and the aromatic vinyl monomer unit is relatively low in polarity, the electrode active material and such a polymer are dispersed in a polar solvent such as water, The polymer tends to be adsorbed on the surface of the electrode active material in a state of agglomerated and agglomerated in the electrode active material layer. On the other hand, since the polymer containing (meth) acrylic acid ester monomer units has a relatively high polarity, it is preferable that the polymer is dispersed in a polar solvent such as water well, dispersed in a polar solvent together with the electrode active material, In the layer, each polymer tends to be separated from each other on the surface of the electrode active material, that is, dispersed and adsorbed onto dots. In particular, it has become clear that the polymer containing an aliphatic conjugated diene monomer unit and an aromatic vinyl monomer unit is in a state of filling a gap formed between electrode active materials. Here, from the viewpoint of improving the rate characteristic, which is one of the electrical characteristics of the secondary battery, it is preferable that the gap between the electrode active materials which are the passages for the movement of the electrode active material ions is not closed. That is, the particulate polymer preferably has adsorption characteristics when a polymer containing a (meth) acrylic acid ester monomer unit is adsorbed on an electrode active material. This makes it difficult for the gaps between the electrode active materials, which serve as the passages for the electrode active material ions to move, to be less likely to be clogged. Furthermore, it is possible to create a state in which the sites into which the electrode active material ions can be inserted are uniformly dispersed on the electrode active material, The rate characteristics of the battery can be improved. Therefore, according to a particulate polymer having a core shell structure in which a polymer containing an aliphatic conjugated diene monomer unit and an aromatic vinyl monomer unit is a core part and a polymer containing a (meth) acrylic acid ester monomer unit is a shell part, And a good adsorption property due to the polymer forming the shell portion can be exhibited.

When the present inventors further proceeded with the examination, it became clear that the dispersibility of the particulate polymer was remarkably improved when the ratio of the (meth) acrylic acid ester monomer units in the shell part of the particulate polymer was 40 mass% or more. Therefore, a particulate polymer having a core shell structure in which a polymer containing an aliphatic conjugated diene monomer unit and an aromatic vinyl monomer unit is used as a core part and a polymer containing 40 mass% or more of a (meth) acrylic acid ester monomer unit is used as a shell part, , It is possible to exhibit excellent binding properties derived from a polymer containing an aliphatic conjugated diene monomer unit and an aromatic vinyl monomer unit and excellent rate characteristics in a polymer-derived secondary battery containing a (meth) acrylic acid ester monomer unit .

≪ Particulate polymer &

The particulate polymer to be contained in the binder composition for a non-aqueous secondary battery electrode of the present invention was obtained by forming an electrode using a non-aqueous secondary battery electrode slurry composition containing the binder composition for a non-aqueous secondary battery electrode of the present invention (For example, an electrode active material) contained in the electrode active material layer in the produced electrode can be kept from being separated from the electrode. Here, the particulate polymer exists in the form of particles in the binder composition and in the slurry composition. As described above, the particulate polymer includes a first polymer in which the core portion contains an aliphatic conjugated diene monomer unit and an aromatic vinyl monomer unit, and a second polymer containing a shell addition (meth) acrylic acid ester monomer unit in an amount of 40 mass% 2 < / RTI > polymer. Further, the first polymer and the second polymer are different polymers. In such a core shell structure, it is preferable that each of the core portion and the shell portion is formed in one layer, but the core portion and the shell portion may be formed by plural layers, respectively. In particular, when the core portion is formed of a plurality of layers, it is preferable that the innermost layer comprises a first polymer containing an aliphatic conjugated diene monomer unit and an aromatic vinyl monomer unit. Normally, the shell portion covers the entire outer surface of the core portion, but the shell portion does not need to surround the entire outer surface of the core portion as long as the effect of the present invention is exhibited.

Furthermore, the swelling degree of the particulate polymer contained in the binder composition for a non-aqueous secondary battery electrode of the present invention is 2.5 times or less. When the degree of swelling of the particulate polymer with respect to the electrolytic solution is 2.5 times or less, deterioration of the bonding strength of the electrode composite layer in the electrolyte to the current collector can be suppressed and the high temperature cycle characteristics of the secondary battery can be further improved. When the degree of swelling of the particulate polymer with respect to the electrolytic solution is 2.5 times or less, the particulate polymer swells excessively in the electrolytic solution to inhibit the movement of ions contributing to the cell reaction, thereby further improving the rate characteristics of the secondary battery .

In the present invention, the " degree of swelling with respect to the electrolytic solution " of the particulate polymer is a value (times) divided by the weight after immersion in the case of immersing a film formed by molding the particulate polymer into a specific electrolytic solution under predetermined conditions Specifically, the film is formed using the method described in the examples of this specification, and the film is measured using the measuring method described in this embodiment.

The swelling degree of the particulate polymer with respect to the electrolytic solution is preferably 1.0 times or more, more preferably 2.0 times or less, more preferably 1.8 times or less, and most preferably 1.7 times or less. By making the degree of swelling of the particulate polymer with respect to the electrolytic solution to be higher than the lower limit described above, the mobility of the electrode active material ions in the secondary battery is improved, the internal resistance of the secondary battery is reduced, and the rate characteristic of the secondary battery is further improved .

The degree of swelling of the particulate polymer with respect to the electrolyte can be adjusted by changing the kind and amount of the monomers to be used. For example, the amount of the aromatic vinyl monomer or the crosslinkable monomer may be increased, the polymerization temperature may be increased, The degree of swelling of the electrolyte solution can be lowered by increasing the polymerization molecular weight.

- first polymer (core part) -

[Aliphatic conjugated diene monomer unit]

The first polymer contained in the core portion of the particulate polymer contains an aliphatic conjugated diene monomer unit. By containing an aliphatic conjugated diene monomer unit in the first polymer, the swelling degree of the particulate polymer can be prevented from becoming excessively large, and the high-temperature cycle characteristics of the secondary battery can be improved. The aliphatic conjugated diene monomer unit is a structural unit derived from an aliphatic conjugated diene monomer. Examples of the aliphatic conjugated diene monomer capable of forming an aliphatic conjugated diene monomer unit include 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3- Substituted 1,3-butadiene (chloroprene), substituted straight-chain conjugated pentadiene, substituted and side-chain conjugated hexadiene, and the like. Among them, 1,3-butadiene is preferable as the aliphatic conjugated diene monomer.

These aliphatic conjugated diene monomers may be used singly or in combination of two or more kinds.

The content of the aliphatic conjugated diene monomer unit in the first polymer is preferably 25% by mass or more, more preferably 30% by mass or more, and more preferably 35% by mass or less, based on 100% by mass of all the repeating units in the first polymer. By mass or more, more preferably 60% by mass or less, more preferably 50% by mass or less, still more preferably 40% by mass or less. When the content ratio of the aliphatic conjugated diene monomer unit is not lower than the lower limit described above, the glass transition temperature of the first polymer is appropriately lowered, and the binding property of the binder composition can be further improved. Furthermore, when the content ratio of the aliphatic conjugated diene monomer unit is not more than the upper limit value, the glass transition temperature of the first polymer is prevented from excessively lowering, and the binding property of the binder composition can be further improved.

[Aromatic vinyl monomer unit]

The first polymer contains an aromatic vinyl monomer unit. By containing the aromatic vinyl monomer unit in the first polymer, the swelling degree of the particulate polymer can be prevented from becoming excessively large, and the high-temperature cycle characteristics of the secondary battery can be improved. The aromatic vinyl monomer unit is a structural unit derived from an aromatic vinyl monomer. Examples of the aromatic vinyl monomer capable of forming an aromatic vinyl monomer unit include styrene,? -Methylstyrene, vinyltoluene, divinylbenzene, and the like. These may be used alone or in combination of two or more. Of these, styrene is preferable.

The content of the aromatic vinyl monomer unit in the first polymer is preferably 40% by mass or more, more preferably 50% by mass or more, and more preferably 55% by mass, based on 100% by mass of all the repeating units in the first polymer More preferably not less than 75% by mass, more preferably not more than 70% by mass, even more preferably not more than 65% by mass. By setting the content ratio of the aromatic vinyl monomer units in the first polymer to be equal to or more than the above lower limit value, the glass transition temperature of the first polymer is prevented from being excessively lowered, and the binding property of the binder composition can be further improved. Furthermore, by controlling the content ratio of the aromatic vinyl monomer units in the first polymer to be not more than the upper limit, it is possible to suppress the excessive increase of the glass transition temperature of the first polymer and further improve the binding property of the binder composition.

[Acid group-containing monomer unit]

Furthermore, it is preferable that the first polymer contains an acid group-containing monomer unit. Examples of the acid group-containing monomer capable of forming an acid group-containing monomer unit include a monomer having a carboxylic acid group, a monomer having a sulfonic acid group, a monomer having a phosphoric acid group, and a monomer having a hydroxyl group.

Examples of the monomer having a carboxylic acid group include a monocarboxylic acid and a dicarboxylic acid. Examples of the monocarboxylic acid include acrylic acid, methacrylic acid and crotonic acid. Examples of the dicarboxylic acid include maleic acid, fumaric acid, itaconic acid, and the like.

Examples of the monomer having a sulfonic acid group include vinylsulfonic acid, methylvinylsulfonic acid, (meth) allylsulfonic acid, ethyl (meth) acrylate-2-sulfonate, Oxy-2-hydroxypropanesulfonic acid and the like. In the present specification, " (meth) allyl " means allyl and / or methallyl, and (meth) acryl means acrylic and / or methacrylic.

Further, as the monomer having a phosphoric acid group, there can be mentioned, for example, a monomer selected from the group consisting of 2- (meth) acryloyloxyethyl phosphate, methyl 2- (meth) acryloyloxyethyl phosphate, And the like. In the present specification, "(meth) acryloyl" means acryloyl and / or methacryloyl.

Examples of the monomer having a hydroxyl group include 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate and the like. .

Among them, as the acid group-containing monomer, a monomer having a carboxylic acid group is preferable, and from the viewpoint of improving the polymerizability of the core portion of the particulate polymer, a monocarboxylic acid is preferable, and methacrylic acid is more preferable.

Incidentally, the acid group-containing monomers may be used singly or in combination of two or more kinds.

The content of the acid group-containing monomer units in the first polymer is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and more preferably 1% by mass or less based on 100% by mass of all the repeating units in the first polymer More preferably not more than 7% by mass, more preferably not more than 5% by mass, even more preferably not more than 4% by mass. By setting the content ratio of the acid group-containing monomer units in the first polymer to the above-mentioned lower limit value or more, the dispersion stability of the first polymer in the polymerization solvent at the time of preparation of the particulate polymer can be improved. Furthermore, by controlling the content ratio of the acid group-containing monomer units in the first polymer to be not more than the upper limit value, generation of aggregates at the time of preparation of the particulate polymer can be suppressed and the production efficiency of the binder composition can be improved, The residual moisture content can be reduced and the high-temperature cycle characteristics of the secondary battery can be further improved.

[Other monomer units constituting the first polymer]

Further, the first polymer may contain other monomer units other than the above-mentioned various monomer units. The other monomer unit is not particularly limited, but a known monomer used for preparing a particulate polymer such as a nitrile group-containing monomer unit, a (meth) acrylic acid ester monomer unit, or a crosslinking monomer unit other than an aliphatic conjugated diene monomer unit . When the first polymer contains a (meth) acrylic acid ester monomer unit, the content thereof should be less than 40 mass%, preferably less than 20 mass%, more preferably less than 10 mass%. In the present invention, it is important that the first polymer contains an aliphatic conjugated diene monomer unit and an aromatic vinyl monomer unit, and the kind and amount of other monomers used for forming the first polymer improve the binding property of the binder As long as the properties of the first polymer constituting the core portion to be produced can be exerted.

[Glass transition temperature of first polymer]

The glass transition temperature of the first polymer is not particularly limited, but is preferably -50 ° C or higher, more preferably -30 ° C or higher, more preferably -10 ° C or higher, preferably 35 ° C or lower , More preferably not more than 20 ° C, particularly preferably not more than 15 ° C. If the glass transition temperature of the first polymer is within the above range, the binding property of the binder composition can be further improved. The glass transition temperature of the first polymer is not particularly limited and can be adjusted by changing the kind and amount of the monomers used for the formation of the first polymer.

The glass transition temperature of the first polymer is not particularly limited and can be measured using a differential scanning calorimeter. The measurement sample is obtained by drying the first polymer formed in the preparation process of the particulate polymer.

- Second polymer (shell part) -

[(Meth) acrylic acid ester monomer unit]

The (meth) acrylic acid ester monomer unit is a repeating unit derived from a (meth) acrylic acid ester monomer. Examples of the (meth) acrylic acid ester monomer capable of forming the (meth) acrylic acid ester monomer unit include (meth) acrylic acid alkyl ester and (meth) acrylic acid perfluoroalkyl ester.

Examples of the alkyl (meth) acrylate ester include alkyl acrylates such as methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, t-butyl acrylate, isobutyl acrylate, Acrylate, n-hexyl acrylate, hexyl acrylate, heptyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, nonyl acrylate, decyl acrylate, lauryl acrylate, n-tetradecyl acrylate, Acrylic acid alkyl esters such as methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, t-butyl methacrylate, isobutyl methacrylate, n- Methacrylate, isopentyl methacrylate, hexyl methacrylate, heptyl methacrylate, octyl methacrylate Methacrylates such as acrylate, methacrylate, acrylate, methacrylate, acrylate, methacrylate, acrylate, methacrylate, And alkyl acrylate; and the like.

(Perfluorohexyl) ethyl acrylate, 2- (perfluorohexyl) ethyl acrylate, and 2- (perfluoro (meth) acrylate) perfluoroalkyl ester. (Perfluorodecyl) ethyl acrylate, 2- (perfluorododecyl) ethyl acrylate, ethyl 2- (perfluorodecyl) ethyl acrylate, 2- 2- (perfluoroethyl) ethyl methacrylate, 2- (perfluorohexyl) ethyl methacrylate, 2- (perfluorohexyl) ethyl methacrylate, Methacrylic acid 2- (perfluorohexyl) ethyl methacrylate, 2- (perfluorooctyl) ethyl methacrylate, 2- (perfluorohexyl) methacrylate, 2- ) Ethyl, methacrylic acid 2- (perfluorododecyl) ethyl, methacrylic acid 2- (perfluorotetradecyl) ethyl, methacrylic acid 2- (purple Oro methacrylic acid, such as hexadecyl) of ethyl 2- (perfluoroalkyl) ethyl; and the like.

These may be used alone or in combination of two or more.

Here, from the viewpoint of raising the hydrophobicity of the second polymer constituting the shell portion to an appropriate level to avoid excessive increase in the degree of swelling of the particulate polymer with respect to the electrolytic solution and also setting the glass transition temperature of the second polymer to an appropriate range, The number of carbon atoms of the alkyl group or the perfluoroalkyl group bonded to the non-carbonyloxy oxygen atom of the alkyl ester or (meth) acrylic acid perfluoroalkyl ester is preferably 3 or more, more preferably 4 or more, still more preferably 6 Or more, preferably 14 or less, and more preferably 10 or less. Specifically, the (meth) acrylic acid ester monomer is preferably 2-ethylhexyl acrylate or butyl acrylate, more preferably 2-ethylhexyl acrylate, more preferably 2-ethylhexyl acrylate or 2-ethylhexyl acrylate, from the viewpoint of suppressing excessive swelling of the particulate polymer desirable.

The content of the (meth) acrylic acid ester monomer unit in the second polymer is 40% by mass or more based on 100% by mass of all the repeating units in the particulate polymer. Further, the content of the (meth) acrylic acid ester monomer unit in the second polymer is preferably 45% by mass or more, more preferably 50% by mass or more, further preferably 80% by mass or less, more preferably 70% By mass, and more preferably 60% by mass or less. When the content of the (meth) acrylic acid ester monomer units is not less than the lower limit described above, the affinity between the water-soluble polymer and the particulate polymer in the slurry composition for non-aqueous secondary battery electrodes is improved and the particulate polymer on the electrode active material It can be arranged at intervals. As a result, the rate characteristics of the secondary battery formed using the binder composition for a non-aqueous secondary battery electrode can be improved. Furthermore, when the content ratio of the (meth) acrylic acid ester monomer unit is not more than the upper limit value, the glass transition temperature of the particulate polymer is prevented from being extremely lowered, and the binding property of the binder composition can be further improved.

[Aromatic vinyl monomer unit]

Further, it is preferable that the second polymer contains an aromatic vinyl monomer unit. By containing the aromatic vinyl monomer unit in the second polymer, the swelling degree of the particulate polymer can be prevented from becoming excessively large, and the high-temperature cycle characteristics of the secondary battery can be further improved. Here, the same aromatic vinyl monomers as those listed above for the first polymer can be used. However, the aromatic vinyl monomers used for the first polymer and the aromatic vinyl monomers used for the second polymer may be the same or different do. In particular, styrene is preferable as the aromatic vinyl monomer.

The content of the aromatic vinyl monomer units in the second polymer is preferably 20 mass% or more, more preferably 30 mass% or more, and more preferably 40 mass% or more, More preferably 60% by mass or less, more preferably 55% by mass or less, and most preferably 50% by mass or less. By setting the content ratio of the aromatic vinyl monomer units in the second polymer to be equal to or more than the lower limit value described above, excessive deterioration of the glass transition temperature of the second polymer can be suppressed and the binder property of the binder composition can be further improved. Furthermore, by setting the content ratio of the aromatic vinyl monomer units in the second polymer to be not more than the upper limit, the excessive increase of the glass transition temperature of the second polymer can be suppressed, and the binding property of the binder composition can be further improved.

[Acid group-containing monomer unit]

Further, it is preferable that the second polymer contains an acid group-containing monomer unit. As the acid group-containing monomer capable of forming an acid group-containing monomer unit, the same acid group-containing monomer that can be used for the first polymer can be used. Among them, a dicarboxylic acid is preferable as the acid group-containing monomer from the viewpoints of suppressing an increase in viscosity over time and improving the time-course stability of the binder composition and the slurry composition for a non-aqueous secondary battery electrode, Among them, itaconic acid is more preferable.

The content of the acid group-containing monomer units in the second polymer is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and more preferably 1% by mass or less based on 100% by mass of all the repeating units in the second polymer More preferably 10% by mass or less, more preferably 7% by mass or less, and most preferably 5% by mass or less. By setting the content ratio of the acid group-containing monomer units in the second polymer to the above-mentioned lower limit value or more, the dispersion stability of the particulate polymer in the binder composition and the slurry composition for a non-aqueous secondary battery electrode can be improved. Furthermore, by controlling the content ratio of the acid group-containing monomer units in the second polymer to be not more than the upper limit, it is possible to reduce the amount of moisture to be fed into the secondary battery due to the particulate polymer, thereby suppressing the decomposition of the electrolyte in the electrolyte, The characteristics can be further improved.

[Crosslinkable monomer unit]

Furthermore, it is preferable that the second polymer contains a crosslinkable monomer unit. The crosslinkable monomer unit is a structural unit derived from a crosslinkable monomer. The crosslinkable monomer is a monomer capable of forming a crosslinked structure during polymerization or after polymerization by heating or irradiation with energy rays. By including the crosslinkable monomer unit, the swelling degree of the particulate polymer can be lowered and the binding property of the particulate polymer can be further improved, and the high temperature cycle characteristics of the secondary battery can be further improved.

As the crosslinkable monomer, for example, a polyfunctional monomer having two or more polymerization reactive groups in the monomer may be mentioned. Examples of such polyfunctional monomers include divinyl compounds such as divinylbenzene, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, ethylene glycol dimethacrylate, diethylene glycol diacrylate, 1, Tri (meth) acrylic acid ester compounds such as trimethylolpropane trimethacrylate and trimethylolpropane triacrylate; di (meth) acrylic acid ester compounds such as 3-butylene glycol diacrylate and allyl methacrylate; Ethylenically unsaturated monomers containing an epoxy group such as allyl glycidyl ether and glycidyl methacrylate; And the like. Among them, it is preferable to use ethylene glycol dimethacrylate or allyl methacrylate, and it is more preferable to use ethylene glycol dimethacrylate. These may be used singly or in combination of two or more in an arbitrary ratio.

The content of the crosslinkable monomer unit in the second polymer is preferably 0.05% by mass or more, more preferably 0.1% by mass or more, more preferably 0.2% by mass or more, More preferably 5% by mass or less, more preferably 3% by mass or less, even more preferably 2% by mass or less, still more preferably 1% by mass or less. When the content of the crosslinkable monomer units is within the above range, the binding property of the particulate polymer can be further improved and the high-temperature cycle characteristics of the secondary battery can be further improved.

[Other monomer units constituting the second polymer]

Further, the second polymer may contain other monomer units other than the above-mentioned various monomer units. Other monomer units include, but are not limited to, known monomers used in the preparation of particulate polymers such as aliphatic conjugated diene monomers and nitrile group-containing monomer units. Here, in the present invention, it is important that the second polymer constituting the shell portion contains 40 mass% or more of (meth) acrylic acid ester monomer units, and the kind and amount of other monomers used for forming the second polymer Type and quantity.

[Glass transition temperature of the second polymer]

The glass transition temperature of the second polymer is not particularly limited, but is preferably -60 ° C or higher, more preferably -35 ° C or higher, more preferably -20 ° C or higher, preferably 20 ° C or lower, Deg.] C or less, more preferably 0 [deg.] C or less. If the glass transition temperature of the second polymer is within the above range, the binding property of the binder composition can be further improved. The glass transition temperature of the second polymer is not particularly limited and may be adjusted by changing the type and amount of the monomers used for the formation of the second polymer.

The glass transition temperature of the second polymer is not particularly limited and can be measured using a differential scanning calorimeter. When measuring the glass transition temperature of the second polymer, a measurement sample containing only the second polymer can be prepared by polymerizing a monomer having a blend ratio used for constituting the shell portion of the particulate polymer of the present invention.

≪ Thickness of shell part of particulate polymer &

The thickness of the shell portion of the particulate polymer is preferably 0.1% or more, more preferably 0.8% or more, more preferably 1% or more, still more preferably 5% or more of the volume average particle diameter (D50) , And particularly preferably 10% or more, more preferably 30% or less, more preferably 20% or less, and most preferably 15% or less. When the thickness of the shell portion of the particulate polymer is not less than the lower limit described above, the particulate polymer can be disposed apart from the surface of the electrode active material by exhibiting the characteristics of the second polymer constituting the shell portion, Can be further improved. Further, when the thickness of the shell portion of the particulate polymer is not more than the upper limit, the binding property of the binder composition can be further improved by exhibiting the properties of the first polymer constituting the core portion.

≪ Volume average particle diameter (D50) of the particulate polymer &

The volume average particle diameter (D50) of the particulate polymer is preferably 50 nm or more, more preferably 100 nm or more, further preferably 200 nm or more, more preferably 1000 nm or less, nm or less. When the volume average particle diameter (D50) of the particulate polymer is not lower than the lower limit value described above, the binding properties of the binder composition can be further improved and the increase in the internal resistance of the secondary battery due to the increase in surface area of the particulate polymer can be suppressed, The rate characteristic of the secondary battery can be further improved. Further, when the volume average particle size (D50) of the particulate polymer is not more than the upper limit, the surface of the electrode active material tends to be easily wrapped. Further, the lowering of the strength of the particulate polymer itself is suppressed, The high-temperature cycle characteristics of the secondary battery can be further improved.

≪ Process for preparing particulate polymer &

The particulate polymer having the core shell structure described above can be prepared by, for example, polymerizing stepwise using various monomers for forming the first polymer in the core part and various monomers for forming the second polymer in the shell part have. Specifically, the particulate polymer can be obtained by firstly forming a core part by a one-stage polymerization or a multi-stage polymerization using a monomer composition for forming a first polymer in the core part, then polymerizing the monomer composition for forming a second polymer in the shell part in the presence of the core part To form a shell part. The polymerization of the monomer composition for forming the first polymer and the monomer composition for forming the second polymer is not particularly limited and may be carried out in an aqueous solvent such as water. The content of each monomer in the monomer composition used in the polymerization is usually the same as the content of the repeating unit (monomer unit) in the polymer obtained by polymerizing the monomer unit.

The polymerization mode is not particularly limited, and any of the solution polymerization method, suspension polymerization method, bulk polymerization method, emulsion polymerization method and the like can be used. As the polymerization reaction, for example, any reaction such as ionic polymerization, radical polymerization, and living radical polymerization can be used. Among them, emulsion polymerization method is particularly preferable from the viewpoint of production efficiency. The emulsion polymerization can be carried out according to a conventional method.

A commonly used emulsifier, dispersant, polymerization initiator, polymerization assistant, chain transfer agent, molecular weight regulator and the like used in the polymerization of the first and second polymers may be used, do. When the first polymer is polymerized, seed polymerization may be carried out using seed particles. The polymerization conditions may also be arbitrarily selected depending on the polymerization method and the kind of the polymerization initiator.

Here, the volume average particle size (D50) of the particulate polymer and the thickness of the shell portion can be adjusted by adjusting, for example, the amount of the emulsifier to be added, the amount of the monomer, and the like in each of the step of obtaining the first polymer and the step of obtaining the second polymer It can be set to a desired range.

≪ Other components >

The binder composition of the present invention may contain, in addition to the above particulate polymer, components such as a conductive auxiliary agent, a reinforcing agent, a leveling agent, a viscosity adjusting agent, and an electrolyte additive. These are not particularly limited as long as they do not affect the cell reaction, and known ones such as those described in International Publication No. 2012/115096 can be used. These components may be used singly or in combination of two or more in an arbitrary ratio.

≪ Preparation of binder composition >

The binder composition of the present invention can be prepared by dispersing the above-described components in an aqueous medium as a dispersion medium. Specifically, by mixing the above-described components and an aqueous medium using a mixer such as a ball mill, a sand mill, a bead mill, a pigment disperser, a brain ball, an ultrasonic disperser, a homogenizer, a planetary mixer and a fill mix, A composition can be prepared.

When the monomer composition is prepared by polymerizing a monomer composition in an aqueous solvent, the particulate polymer can be directly mixed with other components in an aqueous dispersion state. When the particulate polymer is mixed in an aqueous dispersion state, water in the aqueous dispersion may be used as the aqueous medium.

(Slurry composition for non-aqueous secondary battery electrode)

The slurry composition for a non-aqueous secondary battery electrode of the present invention comprises the above-mentioned binder composition, a water-soluble polymer, and an electrode active material. Such a slurry composition for a non-aqueous secondary battery electrode can form an electrode composite layer having excellent bondability to a current collector and can improve the electrical characteristics of the secondary battery including the electrode composite layer.

<Water-soluble polymer>

The water-soluble polymer is adsorbed on the surface of the electrode active material in the slurry composition for a non-aqueous secondary battery electrode on a slurry, or on the surface of the conductive material when the composition contains a conductive material. This is a component contributing to the dispersion stabilization of the conductive material. Furthermore, the water-soluble polymer can increase the viscosity of the slurry composition for a non-aqueous secondary battery electrode, thereby securing the coating while suppressing the sedimentation of the components in the slurry. Here, the water-soluble polymer is not particularly limited and is a polymer having a polarity of about water-soluble, for example, carboxymethylcellulose, methylcellulose, hydroxypropylmethylcellulose, hydroxyethylmethylcellulose, polyvinylalcohol, poly Carboxylic acid, salts thereof, poly (meth) acrylamide, and the like. Examples of the polycarboxylic acid include polyacrylic acid, polymethacrylic acid, and alginic acid. Also, poly (meth) acrylamide is a polymer containing as a main component a compound having a (meth) acrylamide skeleton. For example, there may be mentioned acrylamide, methacrylamide, N-isopropyl acrylamide, N, N-dimethyl acrylamide, N, N-dimethyl methacrylamide, N, Acrylamide, N, N-dimethylaminopropyl methacrylamide, N-methylol methacrylamide, N-methylol acrylamide, diacetone acrylamide, maleic acid amide, acrylic Amide t-butyl sulfonic acid, and the like, and may further contain a copolymerizable monomer. These water-soluble polymers may be used singly or as a copolymer obtained by combining two or more of them in an arbitrary ratio or by copolymerization.

Here, in the present invention, the term "water-soluble" in the polymer means that a mixture obtained by adding and stirring 1 part by mass (corresponding to solid content) of a polymer per 100 parts by mass of ion-exchanged water is mixed at a temperature of 20 ° C or more and 70 ° C or less, And the pH is adjusted to at least one of the conditions of not less than 3 and not more than 12 (using NaOH aqueous solution and / or HCl aqueous solution for pH adjustment), and when passing through a screen of 250 mesh, Means that the solid content of water does not exceed 50 mass% with respect to the solid content of the added polymer.

Furthermore, the blending amount of the water-soluble polymer in the slurry composition for a non-aqueous secondary battery electrode is preferably at least 0.1 part by mass, more preferably at least 0.3 part by mass, and most preferably at least 0.5 part by mass, relative to 100 parts by mass of the electrode active material And is preferably 5 parts by mass or less, more preferably 3 parts by mass or less, and most preferably 2 parts by mass or less. When the blending amount of the water-soluble polymer is within the above range, the dispersibility of the electrode active material and the like in the slurry can be improved and the rate characteristic of the secondary battery can be improved.

<Electrode Active Material>

The electrode active material is a substance that exchanges electrons in the electrodes (positive and negative electrodes) of the secondary battery. Hereinafter, a slurry composition for a lithium ion secondary battery electrode used for manufacturing an electrode of a lithium ion secondary battery is described as an example of a slurry composition for a nonaqueous secondary battery electrode, and an electrode active material (positive electrode active material , Negative electrode active material).

[Positive electrode active material]

The positive electrode active material is not particularly limited, and a known positive electrode active material used in the positive electrode of a lithium ion secondary battery can be used. Specifically, as the positive electrode active material, a compound containing a transition metal, for example, a transition metal oxide, a transition metal sulfide, a composite metal oxide of lithium and a transition metal, and the like can be used. Examples of the transition metal include Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Mo.

Here, as a transition metal oxide, such as _{MnO, MnO 2, V 2 O} 5, V 6 O 13, TiO 2, Cu 2 V 2 O 3, amorphous _{V 2 O-P 2 O 5} , amorphous MoO _3, amorphous V ₂ O ₅ , amorphous V ₆ O ₁₃ , and the like.

Examples of transition metal sulfides include TiS ₂ , TiS ₃ , amorphous MoS ₂ , and FeS.

Examples of the composite metal oxide of lithium and a transition metal include a lithium-containing composite metal oxide having a layered structure, a lithium-containing composite metal oxide having a spinel structure, and a lithium-containing composite metal oxide having an olivine structure.

Examples of the lithium-containing composite metal oxide having a layered structure include lithium-containing cobalt oxide (LiCoO ₂ ), lithium-containing nickel oxide (LiNiO ₂ ), lithium-containing composite oxide of Co-Ni-Mn, Lithium-containing complex oxides, lithium-containing complex oxides of Ni-Co-Al, solid solutions of LiMaO ₂ and Li ₂ MbO ₃ , and the like. Examples of solid solutions of LiMaO ₂ and Li ₂ MbO ₃ include xLiMaO _2. (1-x) Li ₂ MbO ₃ and the like. Here, x represents a number satisfying 0 &lt; x &lt; 1, Ma represents at least one transition metal having an average oxidation state of 3+, and Mb represents one or more transition metals having an average oxidation state of 4+.

In the present specification, the "average oxidation state" refers to the average oxidation state of the above "one or more transition metals" and is calculated from the molar amount and the valence of the transition metal. For example, when "at least one transition metal" is composed of 50 mol% of Ni ²⁺ and 50 mol% of Mn ⁴⁺ , the average oxidation state of "one or more transition metals" 2 +) + (0.5) x (4+) = 3+.

Examples of the lithium-containing composite metal oxide having a spinel structure include compounds obtained by substituting a part of Mn of lithium manganese oxide (LiMn ₂ O ₄ ) or lithium manganese oxide (LiMn ₂ O ₄ ) with another transition metal . Specific examples thereof include Li _s [Mn _2-t Mc _t ] O ₄ . Here, Mc represents one or more transition metals having an average oxidation state of 4+. Specific examples of Mc include Ni, Co, Fe, Cu, and Cr. T represents a number satisfying 0 &lt; t &lt; 1, and s represents a number satisfying 0? S? 1. As the positive electrode active material, a lithium-excess spinel compound represented by Li _{1 + x} Mn _{2 -x} O ₄ (0 <X <2) may also be used.

Examples of the lithium-containing composite metal oxide having an olivine structure include olivine-type lithium phosphate compounds represented by Li _y MdPO ₄ such as olivine-type iron phosphate lithium (LiFePO ₄ ) and olivine-type manganese phosphate lithium (LiMnPO ₄ ) . Here, Md represents one or more transition metals having an average oxidation state of 3+, and examples thereof include Mn, Fe, and Co. Y represents a number satisfying 0? Y? 2. Furthermore, the olivine-type lithium phosphate compound represented by Li _y MdPO ₄ may be partially substituted with another metal having Md. Examples of the substitutable metal include Cu, Mg, Zn, V, Ca, Sr, Ba, Ti, Al, Si, B and Mo.

Among the above, lithium-containing cobalt oxide (LiCoO ₂ ) or olivine-type lithium iron phosphate (LiFePO ₄ ) is used as the positive electrode active material from the viewpoint of improving the high-temperature cycle characteristics and initial capacity of the secondary battery using the positive electrode formed using the slurry composition. ) Is preferably used.

It is preferable to use a positive electrode active material containing at least one of Mn and Ni as the positive electrode active material from the viewpoint of increasing the amount of the lithium ion secondary battery using the positive electrode formed using the slurry composition. Specifically, from the viewpoint of high capacity of the lithium ion secondary battery, LiNiO ₂ , LiMn ₂ O ₄ , lithium excess spinel compound, LiMnPO ₄ , Li [Ni _0.5 Co _0.2 Mn _0.3 ] O ₂ , Li [Ni _1/3 Co _1/3 Mn _1/3 ] O ₂ , Li [Ni _0.17 Li _0.2 Co _0.07 Mn _0.56 ] O ₂ , and LiNi _0.5 Mn _1.5 O ₄ are preferably used as the positive electrode active material and LiNiO ₂ , , Li [Ni _0.5 Co _0.2 Mn _0.3 ] O ₂ , Li [Ni _1/3 Co _1/3 Mn _1/3 ] O ₂ , Li [Ni _0.17 Li _0.2 Co _0.07 Mn _0.56 ] O ₂ or the like as a positive electrode active material , And it is particularly preferable to use Li [Ni _0.5 Co _0.2 Mn _0.3 ] O ₂ as the positive electrode active material.

The particle size of the positive electrode active material is not particularly limited and may be the same as that of the conventional positive electrode active material.

[Negative electrode active material]

The negative electrode active material is not particularly limited and a known negative electrode active material used in the negative electrode of a lithium ion secondary battery can be used. Specifically, as the negative electrode active material, a material capable of absorbing and desorbing lithium is generally used. Examples of the substance capable of intercalating and deintercalating lithium include a carbon-based negative electrode active material, a metal-based negative electrode active material, and a negative electrode active material obtained by combining them.

Here, the carbon-based negative electrode active material refers to an active material having carbon as a main skeleton capable of inserting lithium (also referred to as &quot; doping &quot;). Examples of the carbon-based negative electrode active material include carbonaceous materials and graphite materials have.

Examples of the carbonaceous material include easily graphite carbon which easily changes the structure of carbon according to the heat treatment temperature or non-graphite carbon which has a structure close to the amorphous structure typified by glassy carbon .

As the graphitic carbon, there can be mentioned, for example, a carbon material obtained from a tar pitch obtained from petroleum or coal as a raw material. Specific examples thereof include coke, mesocarbon microbeads (MCMB), mesophase pitch-based carbon fibers, and pyrolysis gas phase grown carbon fibers.

Examples of the non-graphitizable carbon include phenolic resin fired bodies, polyacrylonitrile carbon fibers, (pseudo) isotropic carbon, furfuryl alcohol resin fired bodies (PFA), hard carbon, and the like.

Examples of the graphite material include graphite (graphite) such as natural graphite and artificial graphite.

The metal negative electrode active material is an active material containing a metal and usually includes an element capable of inserting lithium into the structure and has an theoretical capacity per unit mass of 500 mAh / g or more when lithium is inserted . (For example, Ag, Al, Ba, Bi, Cu, Ga, Ge, In, Ni, P, Pb, Sb, and Si that can form a lithium metal or a lithium alloy can be used as the metal- , Sn, Sr, Zn, Ti, etc.) and alloys thereof, and their oxides, sulfides, nitrides, silicides, carbides, phosphides and the like. Among them, an active material containing silicon (silicon based negative electrode active material) is preferable. This is because the capacity of the lithium ion secondary battery can be increased by using the silicon negative electrode active material.

Examples of the silicon based negative electrode active material include a composite material of a silicon-containing material, a silicon-containing alloy, a silicon-containing material formed by coating or compounding SiO 2, SiO _x , or a Si-containing material with conductive carbon, . These silicon based negative electrode active materials may be used singly or in combination of two or more kinds.

Examples of the alloy containing silicon include an alloy composition containing silicon, a transition metal such as aluminum and iron, and further containing a rare earth element such as tin and yttrium.

SiO _x is a compound containing at least one of SiO and SiO ₂ and Si, and x is usually 0.01 or more and less than 2. SiO _x can be formed by using a disproportionation reaction of, for example, silicon monoxide (SiO 2). Specifically, SiO _x can be prepared by subjecting SiO to heat treatment in the presence of a polymer such as polyvinyl alcohol optionally to produce silicon and silicon dioxide. Further, the heat treatment can be carried out at a temperature of 900 ° C or higher, preferably 1000 ° C or higher, in an atmosphere containing SiO 2 and optionally a polymer, and then containing an organic gas and / or a vapor.

As the composite material of the Si-containing material and the conductive carbon, for example, a pulverized mixture of SiO 2 and a polymer such as polyvinyl alcohol, and optionally a carbon material is heat-treated in an atmosphere containing, for example, an organic gas and / And the like. It is also known that the surface of the SiO 2 particles is coated by a chemical vapor deposition method using an organic gas or the like, a method in which particles of SiO 2 and graphite or artificial graphite are compounded (granulated) by mechanochemical method Which can be obtained by conventional methods.

<Binder composition>

As the binder composition that can be incorporated into the slurry composition for a non-aqueous secondary battery electrode, the binder composition for a non-aqueous secondary battery electrode of the present invention containing the particulate polymer described above can be used. The above-mentioned particulate polymer contained in the binder composition functions as at least a part of the binder material in the electrode composite layer formed by using the slurry composition for a non-aqueous secondary battery electrode. The blending amount of the binder composition in the slurry composition for a non-aqueous secondary battery electrode is preferably adjusted such that the mixing ratio of the particulate polymer is in the following range based on the electrode active material and the water-soluble polymer.

[Blending amount of particulate polymer (based on electrode active material)]

That is, the blend amount of the particulate polymer in the slurry composition for a non-aqueous secondary battery electrode of the present invention is preferably at least 0.1 part by mass, more preferably at least 0.3 part by mass, and most preferably at least 0.5 part by mass with respect to 100 parts by mass of the electrode active material More preferably 5 parts by mass or less, more preferably 3 parts by mass or less, and most preferably 2 parts by mass or less. If the blending amount of the particulate polymer is not lower than the lower limit value described above, it is possible to sufficiently increase the peel strength of the electrode formed using the slurry composition for a non-aqueous secondary battery electrode and to further improve the high temperature cycle characteristics of the secondary battery having such an electrode . If the blend amount of the particulate polymer is not more than the upper limit value, the rate characteristics of the secondary battery including the electrode formed using the slurry composition for a non-aqueous secondary battery electrode can be further improved.

[Blend amount of particulate polymer (based on water-soluble polymer)]

The blending amount of the particulate polymer in the slurry composition for a non-aqueous secondary battery electrode of the present invention is preferably at least 0.1 times, more preferably at least 0.5 times, more preferably at least 0.7 times as large as the blending amount of the water-soluble polymer More preferably 5 times or less, and more preferably 2 times or less. By setting the blending amount of the particulate polymer on the basis of the water-soluble polymer within the above-mentioned range, the particulate polymer can be appropriately separated from the surface of the electrode active material, and the rate characteristic of the secondary battery can be further improved.

<Conductive supplements>

The conductive auxiliary agent is for securing electrical contact between the electrode active materials. The conductive auxiliary agent is not particularly limited and a known conductive auxiliary agent can be used. Specifically, for example, as the conductive auxiliary agent for the positive electrode of a lithium ion secondary battery, a conductive carbon material such as acetylene black, Ketjenblack (registered trademark), carbon black, graphite, various metal fibers, foil and the like can be used. Of these, acetylene black, Ketjenblack (registered trademark), and Ketjenblack (registered trademark) are used as the conductive auxiliary agent from the viewpoint of improving the electrical contact between the positive electrode active materials and improving the electrical characteristics of the lithium ion secondary battery using the positive electrode formed using the slurry composition. Carbon black and graphite are preferably used, and it is particularly preferable to use acetylene black or Ketjenblack (registered trademark).

<Other Polymers>

Here, the slurry composition for a non-aqueous secondary battery electrode of the present invention may optionally contain, as a binder, a polymer different from the particulate polymer contained in the water-soluble polymer and the binder composition (hereinafter, May be referred to as &quot; other polymer &quot;). Examples of other polymers include fluorine-containing polymers, acrylonitrile polymers, and the like.

<Other additives>

Other components that can be blended in the slurry composition for a non-aqueous secondary battery electrode of the present invention are not particularly limited other than the above components, and the same components as the other components that can be blended in the binder composition of the present invention can be mentioned. The other components may be used singly or in combination of two or more in an arbitrary ratio.

&Lt; Preparation of slurry composition for secondary battery electrode &

The slurry composition for a non-aqueous secondary battery electrode of the present invention can be prepared by dispersing the respective components in an aqueous medium as a dispersion medium. Specifically, each component and the aqueous medium are mixed using a mixer such as a ball mill, a sand mill, a bead mill, a pigment disperser, a brain ball, an ultrasonic disperser, a homogenizer, a planetary mixer and a fill mix, A composition can be prepared. The mixing of the components and the aqueous medium is usually carried out at room temperature to 80 ° C for 10 minutes to several hours.

Here, water is usually used as the aqueous medium, but an aqueous solution of an arbitrary compound or a mixed solution of a small amount of an organic medium and water may be used. Water used as an aqueous medium may also contain water contained in the binder composition.

(Electrode for non-aqueous secondary battery)

The electrode for a non-aqueous secondary battery of the present invention is obtained by applying a slurry composition for a non-aqueous secondary battery electrode obtained as described above onto a current collector and forming a slurry composition for a non-aqueous secondary battery electrode . That is, the electrode for a non-aqueous secondary battery of the present invention comprises an electrode composite layer formed by using the slurry composition for a non-aqueous secondary battery electrode of the present invention. The nonaqueous secondary battery electrode of the present invention is obtained through a step of applying the slurry composition and a step of drying the slurry composition.

That is, the electrode for a non-aqueous secondary battery of the present invention comprises a dried product of the above-described slurry composition for a non-aqueous secondary battery electrode, and contains at least an electrode active material, the particulate polymer described above, and a water-soluble polymer. When the above-mentioned water-soluble polymer and / or particulate polymer contains a crosslinkable monomer unit, the polymer and / or polymer containing the crosslinkable monomer unit is preferably used in the case of drying the slurry composition for a non-aqueous secondary battery electrode, Or may be crosslinked at the time of heat treatment arbitrarily conducted after drying (that is, the electrode for a non-aqueous secondary battery may contain a crosslinked product of the water-soluble polymer and / or the particulate polymer). The particulate polymer is present in the binder composition and in the form of particles in the slurry composition, but may be in the form of particles or any other arbitrary shape among the electrode composite layers formed using the slurry composition.

Furthermore, in the electrode for a non-aqueous secondary battery of the present invention, the particulate polymer of the core shell structure described above preferably retains the core shell structure. Thus, when the binder according to the present invention is used, for example, in a positive electrode, deterioration of the first polymer forming the core portion can be suppressed.

The respective components contained in the electrode were contained in the slurry composition for a non-aqueous secondary battery electrode of the present invention. The proportional proportion of each component in the slurry composition is the same as that of the non-aqueous secondary battery electrode slurry of the present invention Is the same as the proportional occurrence ratio of each component in the composition. Since the electrode for a non-aqueous secondary battery of the present invention uses the binder composition of the present invention, it has a high peel strength and can exhibit good rate characteristics and high-temperature cycle characteristics in the secondary battery.

[Application step]

The method for applying the slurry composition for a secondary battery electrode onto the current collector is not particularly limited and a known method can be used. As a specific coating method, a doctor blade method, a dipping method, a reverse roll method, a direct roll method, a gravure method, an extrusion method, a brush coating method and the like can be used. At this time, the slurry composition may be applied to only one surface of the current collector, or may be applied to both surfaces. The thickness of the slurry film on the current collector before drying after application can be appropriately set in accordance with the thickness of the electrode composite layer obtained by drying.

[Drying process]

The method for drying the slurry composition on the current collector is not particularly limited and a known method can be used. For example, a drying method by hot air, hot air, low-humidity air, vacuum drying, . By drying the slurry composition on the current collector in this manner, an electrode composite layer is formed on the current collector, and an electrode for a secondary battery including a current collector and an electrode composite layer can be obtained.

After the drying step, a pressure treatment may be applied to the electrode composite layer by using a mold press, a roll press, or the like. By the pressing treatment, the adhesion between the electrode composite layer and the current collector can be improved, and the porosity of the electrode can be lowered.

An example of another manufacturing method of the electrode for a secondary battery of the present invention is a powder forming method. The powder forming method is a method in which a slurry composition for preparing an electrode for a secondary battery is prepared, composite particles including an electrode active material and the like are prepared from the slurry composition, the composite particles are supplied onto a current collector, To form an electrode composite layer to obtain an electrode for a secondary battery. At this time, as the slurry composition, the same slurry composition as described above can be used.

(Secondary battery)

The secondary battery of the present invention includes a positive electrode, a negative electrode, an electrolyte, and a separator, and at least one of the positive electrode and the negative electrode uses the electrode for a secondary battery of the present invention. Since the secondary battery of the present invention uses the above-described electrode, it has excellent rate characteristics and high-temperature cycle characteristics.

The secondary battery of the present invention may be a lithium ion secondary battery, a nickel hydrogen secondary battery, or the like. Among them, a lithium ion secondary battery is preferable in that the performance improving effect such as high-temperature cycle characteristics is particularly remarkable. Hereinafter, the case where the secondary battery of the present invention is a lithium ion secondary battery will be described.

<Electrode>

As described above, the electrode for a secondary battery of the present invention is used as at least one of a positive electrode and a negative electrode. That is, the positive electrode of the secondary battery of the present invention may be an electrode for a secondary battery of the present invention, the negative electrode may be a known negative electrode, and the negative electrode of the secondary battery of the present invention may be an electrode for a secondary battery of the present invention, And both the positive electrode and the negative electrode of the secondary battery of the present invention may be the electrode for the secondary battery of the present invention.

<Electrolyte>

As the electrolyte solution for a lithium ion secondary battery, for example, a non-aqueous electrolyte solution in which a supporting electrolyte is dissolved in a non-aqueous solvent is used. As the supporting electrolyte, a lithium salt is usually used. As the lithium salt, _{e.g., 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, and the like _{(CF 3 SO 2) 2 NLi} , (C 2 F 5 SO 2) NLi. Of these, LiPF ₆ , LiClO ₄ , and CF ₃ SO ₃ Li are preferred because they are easily soluble in solvents and exhibit a high degree of dissociation. These may be used singly or in combination of two or more in an arbitrary ratio. The higher the degree of dissociation of the supporting electrolyte, the higher the lithium ion conductivity. Therefore, the lithium ion conductivity can be controlled depending on the type of the supporting electrolyte.

The nonaqueous solvent is not particularly limited as long as it can dissolve the supporting electrolyte. Examples of the non-aqueous solvent include carbonates such as dimethyl carbonate (DMC), ethylene carbonate (EC), diethyl carbonate (DEC), propylene carbonate (PC), butylene carbonate (BC) and methyl ethyl carbonate (MEC); ethers such as 1,2-dimethoxyethane and tetrahydrofuran; sulfur compounds such as sulfolane and dimethylsulfoxide; and the like. Of these, carbonates are preferable because of high dielectric constant and stable wide potential range. As the non-aqueous solvent, one type may be used alone, or two or more types may be used in combination at an arbitrary ratio.

The electrolytic solution may contain an additive. As the additive, for example, a carbonate compound such as vinylene carbonate (VC) can be mentioned. One kind of additives may be used alone, or two or more kinds of additives may be used in combination at an arbitrary ratio. Examples of the electrolyte solution other than the above include polymer electrolytes such as polyethylene oxide and polyacrylonitrile, gelated polymer electrolytes in which the polymer electrolyte is impregnated with an electrolyte, inorganic solid electrolytes such as LiI and Li ₃ N, etc. do.

<Separator>

As the separator, for example, those described in JP-A-2012-204303 can be used. Among these, a polyolefin resin (polyethylene, polypropylene, polybutene, polyvinyl chloride) is preferably used as the separator in order to reduce the thickness of the entire separator and increase the ratio of the electrode active material in the lithium ion secondary battery to increase the capacity per volume. A microporous membrane is preferable.

<Manufacturing Method of Secondary Battery>

As a specific manufacturing method of the secondary battery of the present invention, for example, a positive electrode and a negative electrode are overlapped with each other with a separator interposed therebetween, and the battery is wrapped or folded according to the shape of the battery, Sealing). Further, if necessary, an overcurrent prevention element such as expanded metal, fuse, or PTC element, or a lead plate may be inserted to prevent an increase in pressure inside the battery and overcharge discharge. The shape of the secondary battery may be a coin type, a button type, a sheet type, a cylindrical type, a square type, a flat type, or the like.

Example

Hereinafter, the present invention will be described concretely based on examples, but the present invention is not limited to these examples. In the following description, &quot;% &quot; and &quot; part &quot; representing amounts are on a mass basis unless otherwise specified.

In Examples and Comparative Examples, the glass transition temperature of each of the first polymer and the second polymer, swelling degree of the particulate polymer with respect to the electrolytic solution, volume average particle diameter (D50), shell thickness, electrode peel strength, And the high temperature cycle characteristics were evaluated using the following methods, respectively.

&Lt; Glass transition temperature of the first polymer and the second polymer &

An aqueous dispersion containing a polymer as a measurement sample under the same polymerization conditions as the polymerization conditions of the first polymer and the second polymer by using each monomer and each additive used in the formation of the first polymer and the second polymer, did. Then, the prepared aqueous dispersion was used as a measurement sample.

Using a differential scanning calorimeter (trade name "EXSTAR DSC6220", manufactured by SIEI NANOTECHNOLOGY Co., Ltd.), the glass transition temperature was measured for each polymer sample.

Specifically, 10 mg of the sample to be measured was weighed in an aluminum pan, and the temperature was measured at a temperature raising rate of 10 占 폚 / minute and a room temperature specified in JIS Z8703 Under normal conditions, the DSC curve was measured. From the intersection of the baseline immediately before the endothermic peak of the DSC curve with the derivative signal DDSC of 0.05 mW / min / mg or more and the tangent line of the DSC curve at the inflection point first appearing after the endothermic peak, The glass transition temperature was determined.

&Lt; Swelling degree of electrolyte (electrolyte swelling degree) &gt;

An aqueous dispersion containing a particulate polymer was prepared and this aqueous dispersion was dried for 3 days under an environment of 50% humidity and 23 to 25 占 폚 to form a film having a thickness of 3 占 0.3 mm. The film thus formed was vacuum-dried at 150 DEG C for 12 hours, cut into a diameter of 12 mm, and precisely weighed.

The mass of the film piece obtained by the cutting is defined as W0. This film piece was mixed with 50 g of an electrolytic solution (composition: LiPF ₆ solution having a concentration of 1.0 M (solvent: mixed solvent of ethylene carbonate / ethyl methyl carbonate = 3/7 (volume ratio), 2% by volume of vinylene carbonate By weight) was immersed in an environment at 60 캜 for 72 hours to swell. Thereafter, the piece of film taken out (after swelling) was lightly wiped off, and the mass W1 was measured.

Then, the degree of swelling (times) was calculated according to the following formula.

Electrolyte swelling degree (times) = W1 / W0

&Lt; Volume average particle diameter (D50) &gt;

The volume average particle diameter (D50) of the particulate polymer was measured using a laser diffraction / scattering type particle size distribution measuring apparatus (LS230, manufactured by Beckman Coulter, Inc.).

Specifically, the particle size-volume cumulative distribution of the particulate polymer was measured for an aqueous dispersion containing the particulate polymer using a laser diffraction / scattering type particle size distribution measuring apparatus, and the particle size at which the volume cumulative distribution value was 50% Volume average particle diameter.

&Lt; Calculation method of thickness ratio of shell part of particulate polymer &gt;

After the particulate polymer was embedded in a resin, osmium was stained and an ultrathin section was prepared by a frozen section. Microscopic observation using a transmission electron microscope (H-7100FA type, manufactured by Hitachi, Ltd.) Respectively. Specifically, the core portion and the shell portion of the particulate polymer were distinguished from each other by the contrast difference derived from osmium dyeing, and the average value of 100 randomly selected particulate polymers was determined as the thickness of the shell portion.

The ratio of the thickness of the shell portion to the volume average particle diameter (D50) of the particulate polymer was calculated by the following formula.

(%) Of the shell portion to the volume average particle diameter (D50) of the particulate polymer = (shell portion thickness / volume average particle diameter (D50) of the particulate polymer) x 100).

&Lt; Peel strength of electrode &

The negative electrode for a lithium ion secondary battery produced in Examples and Comparative Examples was cut into squares of 1.0 cm in width × 10 cm in length to form test pieces and fixed on the surface of the negative electrode composite material layer side up. Then, a cellophane tape was stuck to the surface of the negative electrode mixture layer side of the test piece. At this time, the cellophane tape specified in JIS Z1522 was used. Thereafter, the stress was measured when the cellophane tape was peeled from one end of the test piece at a rate of 50 mm / minute to the 180 占 direction (the other end side of the test piece). The measurement was carried out ten times, and an average value of the stress was obtained. The average value of the stress was evaluated as the peel strength (N / m) by the following criteria. The larger the fill strength, the better the bondability of the negative electrode composite material layer to the current collector.

A: Peel strength of 8 N / m or more

B: Peel strength of 5 N / m or more and less than 8 N / m

C: Peel strength less than 5 N / m

<Rate characteristics of secondary battery>

The produced pouch-type lithium ion secondary battery was allowed to stand still at 23 占 폚 for 24 hours, and then charged to a cell voltage of 4.4 V at a charging / discharging rate of 0.2 C at 25 占 폚 and discharged to a cell voltage of 3.0 V . Thereafter, a charge / discharge cycle in which a cell voltage of 4.4 V was charged at a charge rate of 0.2 C at 25 캜 and a cell voltage of 3.0 V was discharged at a discharge rate of 1.0 C and a discharge cycle of 3.0 V at a discharge rate of 3.0 C And a charge / discharge cycle was performed. The ratio of the battery capacity at the discharge rate of 3.0 C to the battery capacity at the discharge rate of 1.0 C was calculated as a percentage to obtain the charge / discharge rate characteristics. The higher the value of the charge / discharge rate characteristic is, the smaller the internal resistance is, the faster the charge / discharge is possible, and the better the rate characteristic is.

A: charge / discharge rate characteristic is 70% or more

B: charge / discharge rate characteristic is 65% or more and less than 70%

C: charge / discharge rate characteristic is 60% or more and less than 65%

D: charge / discharge rate characteristic less than 60%

<High-temperature cycle characteristics of secondary battery>

The manufactured lithium ion secondary battery was allowed to stand still at 23 占 폚 for 24 hours and then charged to a cell voltage of 4.4 V at a charging / discharging rate of 0.2 C at 25 占 폚 and discharged to a cell voltage of 3.0 V, The capacity C0 was measured. Furthermore, the capacity C1 after 300 cycles was measured by repeatedly charging / discharging the battery at a charging / discharging rate of 1.0 C at a cell voltage of 4.4 V and discharging it to a cell voltage of 3.0 V under a 45 ° C environment. Then, the high-temperature cycle characteristics were evaluated by the capacity retention rate, which is represented by? C = (C1 / C0) x 100 (%). The higher the value of the capacity retention rate is, the lower the discharge capacity is, and the better the high-temperature cycle characteristics are.

A: Capacity retention rate? C is 80% or more

B: Capacity retention rate? C is 75% or more and less than 80%

C: Capacity retention rate? C is less than 75%

(Example 1)

&Lt; Preparation of particulate polymer &

- first polymerization step -

In a 5 MPa pressure vessel equipped with a stirrer, 35.0 parts of 1,3-butadiene as an aliphatic conjugated diene monomer, 63.0 parts of styrene as an aromatic vinyl monomer, 2.0 parts of methacrylic acid as an acid group-containing monomer unit, 0.5 part of dodecylbenzene sulfonate as an emulsifier, 150 parts of ion-exchanged water, and 0.5 part of potassium persulfate as a polymerization initiator were added to the flask. After sufficiently stirring, the mixture was heated to 50 DEG C and maintained at that temperature for 12 hours Then, the temperature was raised to 80 ° C and maintained for 3 hours to complete the polymerization reaction. The aqueous dispersion containing the first polymer thus obtained was once cooled to 30 캜 or lower.

- Second polymerization step -

55.0 parts of 2-ethylhexyl acrylate as a (meth) acrylic acid ester monomer, 42.5 parts of styrene as an aromatic vinyl monomer, 2.0 parts of itaconic acid as an acid group-containing monomer, 2.0 parts of ethylene 0.5 part of glycol dimethacrylate, 0.3 part of sodium dodecylbenzenesulfonate as an emulsifier, 0.3 part of potassium persulfate as a polymerization initiator, and 150 parts of ion-exchanged water were placed and sufficiently stirred. The mixture was heated to 70 占 폚 and maintained for 4 hours, The temperature was raised to 80 캜 and maintained for 3 hours to complete the polymerization reaction and then cooled to 30 캜 or lower.

- Post treatment process -

A 10% sodium hydroxide aqueous solution was added to the aqueous dispersion solution containing the particulate polymer having the core shell structure in which the core portion composed of the first polymer was covered with the shell portion made of the second polymer thus obtained, Adjusted. Thereafter, unreacted monomers were removed by distillation under reduced pressure by heating. Thus, an aqueous dispersion containing a particulate polymer having a first polymer as a core portion and a second polymer as a shell portion was obtained. The volume average particle diameter (D50) of the particulate polymer was 320 nm, and the thickness of the shell portion was 10.9% with respect to the volume average particle diameter (D50). Then, the glass transition temperature of the first polymer and the second polymer, and the electrolyte swelling degree of the particulate polymer were measured. The results are shown in Table 1.

<Preparation of Slurry Composition for Negative Electrode of Lithium Ion Secondary Battery>

100.0 parts of artificial graphite (specific surface area: 1.5 m ² / g, volume average particle diameter: 20 μm) as a negative electrode active material and 100.0 parts of carboxymethyl cellulose sodium salt (CMC-Na) as a water-soluble polymer were added to a planetary mixer with a disper % Aqueous solution was added in an amount of 1.0 part corresponding to the solid content. Then, the mixture was adjusted to a solid content concentration of 60% by ion-exchanged water and mixed at 25 DEG C for 60 minutes.

Next, the solid content concentration was adjusted to 52% with ion-exchanged water and further mixed at 25 占 폚 for 15 minutes to obtain a mixed solution.

Subsequently, 1.0 part of the binder composition composed of the aqueous dispersion of the particulate polymer was added to the mixed solution in an amount corresponding to the solid content, and ion-exchanged water was added thereto to adjust the final solid concentration to 50%. This was degassed under reduced pressure to obtain a negative electrode slurry composition.

&Lt; Preparation of negative electrode for lithium ion secondary battery &gt;

The prepared negative electrode slurry composition was coated on a copper foil (current collector) having a thickness of 15 탆 by a comma coater so that the amount of droplets was 13.5 to 14.5 mg / cm ² and dried. The drying was carried out by conveying the copper foil in an oven at 70 캜 for 2 minutes at a speed of 0.5 m / min. Thereafter, the substrate was heat-treated at 120 DEG C for 2 minutes to obtain a negative electrode cloth. Next, the resultant negative electrode cloth was pressed by a roll press machine so that the bulk density of the negative electrode composite material layer was 1.85 g / cm ³ to obtain a negative electrode. The weight per unit area of the negative electrode composite material layer after pressing was 14.0 mg / cm ² .

Then, the produced negative electrode was evaluated for the peel strength. The results are shown in Table 1.

&Lt; Preparation of positive electrode for lithium ion secondary battery &gt;

(Manufactured by Denki Kagaku Kogyo K.K. and HS-100 manufactured by Denki Kagaku Kogyo K.K.) as a conductive auxiliary agent, and PVDF (polyvinylidene fluoride, available from Kureha Chemical Co., Ltd.) as a positive electrode active material, 96.0 parts of LiCoO ₂ as a positive electrode active material, Ltd., KF-1100) were added, N-methylpyrrolidone was added thereto so that the total solid concentration was 67%, and the mixture was mixed to obtain a positive electrode slurry composition.

Then, the obtained positive electrode slurry composition was coated on an aluminum foil (collector) having a thickness of 20 탆 by a comma coater and dried. The drying was carried out by conveying the aluminum foil in an oven at 60 캜 for 2 minutes at a rate of 0.5 m / min. Thereafter, it was heat-treated at 120 DEG C for 2 minutes to obtain a positive electrode cloth. Next, the obtained positive electrode material was pressed by a roll press machine so that the bulk density of the positive electrode material layer was 3.5 g / cm &lt; ³ &gt; to obtain a positive electrode.

&Lt; Preparation of Lithium Ion Secondary Battery &gt;

A single-layered polypropylene separator (width 65 mm, length 500 mm, thickness 25 μm; manufactured by the dry method; porosity 55%) was prepared and cut into a square of 5 cm × 5 cm. In addition, an aluminum-coated outer sheath was prepared as the outer surface of the battery.

Then, the positive electrode prepared as described above was cut out into a square of 4 cm x 4 cm, and the surface of the collector side was arranged so as to be in contact with the aluminum-covered sheath. Next, a square separator was disposed on the surface of the positive electrode mixture layer side of the positive electrode. Further, the negative electrode prepared as described above was cut into a square of 4.2 cm x 4.2 cm, and the surface of the negative electrode composite material layer side was disposed on the separator so as to face the separator. Thereafter, a LiPF ₆ solution having a concentration of 1.0 M as a solvent (a mixed solvent of ethylene carbonate / methyl ethyl carbonate = 3/7 (volume ratio) and 2% by volume (solvent ratio) of vinylene carbonate as an additive) did. Further, in order to seal the openings of the aluminum-covered sheath, heat sealing at 150 ° C was performed to close the aluminum-covered sheath, thereby manufacturing a lithium ion secondary battery.

The rate characteristics and the high-temperature cycle characteristics of the obtained lithium ion secondary batteries were evaluated. The results are shown in Table 1.

(Examples 2 to 5 and 13 to 14)

A particulate polymer, a binder composition, a slurry composition for a negative electrode, a negative electrode, a positive electrode and a secondary battery were prepared in the same manner as in Example 1 except that the mixing ratios of the monomers were changed to the ratios shown in Tables 1 and 2, 1, various measurements were carried out. The results are shown in Table 1.

(Example 6)

The addition amount of sodium dodecylbenzenesulfonate, which is an emulsifier added at the time of preparing the first polymer, was adjusted to 0.24 parts. Further, the amount of various monomers to be added in the second polymerization step is set so that the composition ratio of various monomer units constituting the second polymer is the same as that in Example 1, while the mixing ratio of various monomers is maintained, The total amount of the various monomers added was changed to 6 parts by mass when the amount of the first polymer was 100 parts by mass. A particulate polymer, a binder composition, a slurry composition for a negative electrode, a negative electrode, a positive electrode and a secondary battery were produced in the same manner as in Example 1 except for this point, and various measurements were carried out in the same manner as in Example 1. The results are shown in Table 1.

(Example 7)

The addition amount of sodium dodecylbenzenesulfonate, which is an emulsifier added at the time of preparing the first polymer, was 0.40 part. Further, the amount of various monomers to be added in the second polymerization step is set so that the composition ratio of various monomer units constituting the second polymer is the same as that in Example 1, while the mixing ratio of various monomers is maintained, Was changed to 360 parts by mass when the total amount of the various monomers added was 100 parts by mass for the first polymer. A particulate polymer, a binder composition, a slurry composition for a negative electrode, a negative electrode, a positive electrode and a secondary battery were produced in the same manner as in Example 1 except for this point, and various measurements were carried out in the same manner as in Example 1. The results are shown in Table 1.

(Example 8)

A particulate polymer, a binder composition, a slurry composition for a negative electrode, a negative electrode, a positive electrode and a secondary battery were prepared in the same manner as in Example 1 except that the acrylic acid ester monomer to be blended in the second polymer was changed to butyl acrylate, 1, various measurements were carried out. The results are shown in Table 1.

(Example 9)

A particulate polymer, a binder composition, a slurry composition for a negative electrode, a negative electrode, a positive electrode and a secondary battery were prepared in the same manner as in Example 1 except that the water-soluble polymer was changed to a polyacrylic acid-polyacrylamide copolymer. In the same manner, various measurements were carried out. The results are shown in Table 1.

(Example 10)

A binder composition, a negative electrode slurry composition, a negative electrode, a positive electrode, and a secondary battery were prepared in the same manner as in Example 1 except that the addition amount of sodium dodecylbenzenesulfonate as an emulsifier added at the time of preparation of the first polymer was changed to 0.80 part. And various measurements were carried out in the same manner as in Example 1. [ The results are shown in Table 1.

(Example 11)

A binder composition, a negative electrode slurry composition, a negative electrode, a positive electrode, and a secondary battery were prepared in the same manner as in Example 1 except that the addition amount of sodium dodecylbenzenesulfonate as an emulsifier added at the time of preparation of the first polymer was changed to 0.14 parts. And various measurements were carried out in the same manner as in Example 1. [ The results are shown in Table 1.

(Example 12)

A particulate polymer and a binder composition were prepared in the same manner as in Example 1. The negative electrode slurry composition, the negative electrode, the positive electrode and the negative electrode were prepared in the same manner as in Example 1, except that the amount of the particulate polymer blended in the negative electrode slurry composition was 0.3 times the amount of the solid content of the water-soluble polymer A secondary battery was produced, and various measurements were carried out in the same manner as in Example 1. The results are shown in Table 2.

(Example 15)

The addition amount of sodium dodecylbenzenesulfonate, which is an emulsifier added at the time of preparing the first polymer, was 0.50 parts. Further, the amount of various monomers to be added in the second polymerization step is set so that the composition ratio of various monomer units constituting the second polymer is the same as that in Example 1, while the mixing ratio of various monomers is maintained, The total amount of the various monomers added was changed to 402 parts by mass when the first polymer was changed to 100 parts by mass. A particulate polymer, a binder composition, a slurry composition for a negative electrode, a negative electrode, a positive electrode and a secondary battery were produced in the same manner as in Example 1 except for this point, and various measurements were carried out in the same manner as in Example 1. The results are shown in Table 2.

(Comparative Example 1)

The amount of the sodium dodecylbenzenesulfonate added as an emulsifier to be added at the time of preparation of the first polymer was adjusted to 0.23 part, and a particulate polymer, a binder composition, and a slurry composition for negative electrode were prepared in the same manner as in Example 1 except that the second polymer was not prepared , A negative electrode, a positive electrode and a secondary battery were manufactured, and various measurements were carried out in the same manner as in Example 1. The results are shown in Table 2.

(Comparative Example 2)

A binder composition, a slurry composition for negative electrode, a composition for a negative electrode, and a composition for a negative electrode were prepared in the same manner as in Example 1, except that the amount of sodium dodecylbenzenesulfonate as an emulsifier was changed to 0.23 parts when the second polymer was prepared without preparing the first polymer. A negative electrode, a positive electrode, and a secondary battery were manufactured, and various measurements were carried out in the same manner as in Example 1. [ The results are shown in Table 2.

(Comparative Example 3)

A particulate polymer, a binder composition, a slurry composition for a negative electrode, a negative electrode, a positive electrode and a secondary battery were prepared in the same manner as in Example 1 except that the mixing ratios of the monomers were changed to the ratios shown in Table 2, And various measurements were made. The results are shown in Table 2.

(Comparative Example 4)

As the particulate polymer, each particulate polymer prepared in Comparative Examples 1 and 2 was used in place of the particulate polymer having a core shell structure. Specifically, in the preparation of the negative electrode slurry composition, the negative electrode slurry composition, the negative electrode, and the negative electrode composition were prepared in the same manner as in Example 1, except that 0.5 parts of each particulate polymer prepared in Comparative Examples 1 and 2, A positive electrode and a secondary battery were prepared and various measurements were carried out in the same manner as in Example 1. [ The results are shown in Table 2.

(Comparative Example 5)

Various monomers and additives added at the time of polymerization of the shell part of Example 1 were added in the first polymerization step to prepare a particulate polymer and polymerization was carried out under the same conditions as in the shell part polymerization in Example 1, , Various monomers and additives added in the polymerization of the core part of Example 1 were added and polymerized under the same conditions as those in the core part polymerization in Example 1. [ The negative electrode slurry composition, the negative electrode, the positive electrode and the positive electrode were prepared in the same manner as in Example 1, except that the particulate polymer having the core shell structure having the core portion composed of the second polymer and the shell portion composed of the first polymer was prepared in this manner. A battery was prepared, and various measurements were carried out in the same manner as in Example 1. The results are shown in Table 2.

(Comparative Example 6)

Except that 55.0 parts of methyl methacrylate was added instead of 55.0 parts of 2-ethylhexyl acrylate in the second polymerization step in preparing the particulate polymer, the negative electrode slurry composition, negative electrode, positive electrode And a secondary battery were fabricated, and various measurements were carried out in the same manner as in Example 1. The results are shown in Table 2.

In the following tables,

&Quot; BD &quot; represents 1,3-butadiene,

&Quot; St &quot; represents styrene,

&Quot; MAA &quot; represents methacrylic acid,

&Quot; 2-EHA &quot; represents 2-ethylhexyl acrylate,

&Quot; BA &quot; represents butyl acrylate,

&Quot; IA &quot; represents itaconic acid,

&Quot; EDMA &quot; represents ethylene glycol dimethacrylate,

&Quot; AMA &quot; represents allyl methacrylate,

&Quot; CMC-Na &quot; represents carboxymethylcellulose sodium salt,

&Quot; PAA-PAM &quot; represents a polyacrylic acid-polyacrylamide copolymer,

&Quot; MMA &quot; represents methyl methacrylate.

From Table 1 and Table 2, it can be seen that it comprises a first polymer having a core shell structure and a core part containing an aliphatic conjugated diene monomer unit and an aromatic vinyl monomer unit, wherein the shell part contains 40 mass% (meth) Or more and a second polymer different from the first polymer, and the binder composition according to Examples 1 to 15, wherein the degree of swelling of the particulate polymer with respect to the electrolytic solution is 2.5 times or less, And further, the electrical characteristics of the secondary battery can be sufficiently improved. On the other hand, the binder composition of Comparative Examples 1 and 2 containing only either one of the first and second polymers or the particulate polymer having a core shell structure contains the acrylic ester monomer units in the shell portion of the particulate polymer Comparative Example 3 in which the first and second polymers are contained but not having a core shell structure, and Comparative Example 4 in which the polymer constituting the core shell structure is opposite to that in Comparative Example 5, And Comparative Example 6 in which the degree of swelling of the particulate polymer with respect to the electrolytic solution is more than 2.5 times can not be combined with the binder as a binder and the electrical characteristics of the secondary battery at a sufficiently high level.

According to the present invention, it is possible to provide a binder composition for a non-aqueous secondary battery electrode which is excellent in binding property and capable of sufficiently increasing the electrical characteristics of the secondary battery.

According to the present invention, there is provided a non-aqueous secondary battery electrode slurry composition capable of forming an electrode composite material layer having excellent bondability to a current collector and capable of improving the electrical characteristics of the secondary battery including the electrode composite material layer, .

Furthermore, according to the present invention, it is possible to provide an electrode for a non-aqueous secondary battery capable of increasing the electrical characteristics of the secondary battery, and a non-aqueous secondary battery having a high electrical characteristic.

Claims (10)

1. A binder composition for a non-aqueous secondary battery electrode comprising a particulate polymer,
Wherein the particulate polymer has a core shell structure having a shell portion on the outermost layer and a core portion on the inner side of the shell portion,
Wherein the core portion comprises a first polymer containing an aliphatic conjugated diene monomer unit and an aromatic vinyl monomer unit,
Wherein the shell portion comprises a second polymer different from the first polymer, the second polymer containing 40 mass% or more of (meth) acrylic acid ester monomer units,
Wherein the degree of swelling of the particulate polymer with respect to the electrolytic solution is 2.5 times or less. The method according to claim 1,
Wherein the first polymer comprises an aliphatic conjugated diene monomer unit in an amount of 25 mass% or more and an aromatic vinyl monomer unit in an amount of 40 mass% or more and 75 mass% or less. 3. The method according to claim 1 or 2,
Wherein the second polymer further comprises 20% by mass or more and less than 60% by mass of an aromatic vinyl monomer unit. 4. The method according to any one of claims 1 to 3,
Wherein the alkyl group or perfluoroalkyl group bonded to the non-carbonyl oxygen atom contained in the (meth) acrylic acid ester monomer unit has 3 or more carbon atoms. 5. The method according to any one of claims 1 to 4,
Wherein the second polymer further comprises from 0.05% by mass to 2% by mass of a crosslinkable monomer unit. 6. The method according to any one of claims 1 to 5,
Wherein the thickness of the shell portion is 0.1% or more and 30% or less with respect to the volume average particle diameter (D50) of the particulate polymer. 7. The method according to any one of claims 1 to 6,
Wherein the particulate polymer has a volume average particle size (D50) of 50 nm or more and 1000 nm or less. A slurry composition for a nonaqueous secondary battery electrode comprising an electrode active material, a water-soluble polymer, and a binder composition for a nonaqueous secondary battery electrode according to any one of claims 1 to 7. An electrode for a nonaqueous secondary battery, comprising an electrode composite layer formed by using the slurry composition for a nonaqueous secondary battery electrode according to claim 8. A nonaqueous secondary battery comprising the electrode for a nonaqueous secondary battery according to claim 9.