JP2014130751A - Binder resin for non-aqueous secondary battery positive electrode, positive electrode for non-aqueous secondary battery, and non-aqueous secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a binder resin for a non-aqueous secondary battery positive electrode capable of achieving dispersion stability of electrode slurry for a positive electrode, flexibility of the positive electrode, and adhesion between a positive electrode mixture layer and a current collector, and also to provide a positive electrode of a non-aqueous secondary battery equipped with the binder resin, and a non-aqueous secondary battery equipped with the positive electrode for the non-aqueous secondary battery.SOLUTION: A binder resin for a non-aqueous secondary battery positive electrode contains a (co)polymer including a monomer unit (a) represented by the general formula (1). A positive electrode for a non-aqueous secondary battery is equipped with the binder resin for the non-aqueous secondary battery positive electrode. The non-aqueous secondary battery is equipped with the positive electrode for the non-aqueous secondary battery.

Description

  The present invention relates to a binder resin for a non-aqueous secondary battery positive electrode, a positive electrode for a non-aqueous secondary battery, and a non-aqueous secondary battery.

  Secondary batteries are used for low-power consumer devices such as notebook computers and mobile phones, and as storage batteries for hybrid vehicles and electric vehicles. Among secondary batteries, lithium ion secondary batteries (hereinafter, simply referred to as “batteries”) are frequently used. Generally, as an electrode for a lithium ion secondary battery, an electrode active material held on a current collector by a binder resin is generally used.

Conventionally, fluorine resin such as polyvinylidene fluoride (PVDF) has been used as a binder resin for battery electrodes, for example, for a positive electrode.
When producing an electrode, an organic solvent such as N-methyl-2-pyrrolidone (NMP) is used as a solvent for making a mixture of an electrode active material, a binder resin, and the like into an electrode slurry.
However, organic solvents such as NMP have problems such as a solvent recovery cost during drying and a high load on the environment.
Therefore, recently, attempts have been made to replace the organic solvent with water. For example, a water-dispersed binder resin such as styrene-butadiene rubber (SBR) latex as a binder resin for a negative electrode, or carboxymethyl cellulose (CMC) as a thickener. ) Is used.

By the way, since water-dispersed binder resin is distribute | circulated in the state containing water, there exists a problem that transportation cost increases. Furthermore, since an antifungal agent is usually added to the water-dispersed binder resin for the purpose of suppressing the generation of mold, there is a concern that the battery performance is degraded.
Therefore, it is desired to provide a water-dispersed binder resin in powder form. However, latex resins often have a low glass transition temperature composition, and once powdered, polymer chains are entangled, and water is added again. There was a problem that it was difficult to disperse in the water.
Therefore, there is a demand for a powdery binder resin that can be used by dissolving or dispersing in water during electrode production so that PVDF powder can be used by dissolving it in NMP.

On the other hand, since CMC is a water-soluble polymer, it can be used by dissolving in water at the time of electrode preparation. However, since CMC is derived from a natural product, the quality of each supply lot is difficult to stabilize, and as a result, the quality of the obtained electrode is difficult to stabilize.
Therefore, a non-natural and water-soluble binder resin that can be supplied with stable quality is desired.
In addition, batteries including a binder resin are required to exhibit high battery performance.

In response to these problems, various polymers have been proposed as water-soluble binder resins.
For example, in Patent Document 1, an aqueous dispersion of a thickener and a water-dispersible binder resin is used.

JP 2002-256129 A

In the positive electrode disclosed in Patent Document 1, it cannot be said that the dispersion stability of the positive electrode slurry, the flexibility of the positive electrode, and the adhesion between the positive electrode mixture layer and the current collector are sufficient.
In addition, the aqueous dispersion containing the thickener and the water-dispersible binder resin used in Patent Document 1 needs to use a component that imparts viscosity and a component that imparts binding properties separately in combination. For this reason, the binder resin cannot be used simply in powder form, and the above-described requirements cannot be satisfied.
The present invention has been made in view of the above circumstances, and without using a binder resin for a non-aqueous secondary battery positive electrode capable of improving battery performance, in particular, CMC, latex binder resin, additives, etc. The dispersion stability of the electrode slurry for the positive electrode, the flexibility of the positive electrode, and the adhesion between the positive electrode mixture layer and the current collector can be improved, and it can be easily used in powder form. It aims at providing the binder resin for water secondary battery positive electrodes, the positive electrode for non-aqueous secondary batteries provided with this binder resin, and the non-aqueous secondary battery provided with this positive electrode for non-aqueous secondary batteries.

  As a result of intensive studies, the present inventors have determined that as a binder resin for a non-aqueous secondary battery positive electrode (hereinafter, simply referred to as “binder resin”) without using CMC, latex binder resin, additives, or the like. By containing a (co) polymer having a monomer unit represented by the following general formula (1), the dispersion stability of the electrode slurry, the flexibility of the positive electrode, and the positive electrode mixture layer and the current collector As a result, the present invention has been completed.

(In the formula (1), ^{R 1} and ^{R 2,} one of ^{R 1} and ^{R 2} is a linear or branched alkyl group having 1 to 12 carbon hydrogen or C, straight other is from 1 to 12 carbon atoms (It is a chain or branched alkyl group. N is an integer of 1 to 30000000.)

That is, the present invention has the following aspects.
[1] A binder resin for a nonaqueous secondary battery positive electrode containing a (co) polymer containing a monomer unit (a) represented by the following general formula (1).

(In the formula (1), ^{R 1} and ^{R 2,} one of ^{R 1} and ^{R 2} is a linear or branched alkyl group having 1 to 12 carbon hydrogen or C, straight other is from 1 to 12 carbon atoms (It is a chain or branched alkyl group. N is an integer of 1 to 30000000.)
[2] A positive electrode for a non-aqueous secondary battery comprising a positive electrode mixture layer containing the binder resin according to [1], a conductive additive, and a positive electrode active material, and a current collector.
[3] A non-aqueous secondary battery comprising the electrode according to [2].

  According to the binder resin of the present invention, it is possible to improve the dispersion stability of the positive electrode slurry. Furthermore, the flexibility of the positive electrode and the adhesion between the positive electrode mixture layer and the current collector can be improved. As a result, non-aqueous secondary batteries including these, particularly lithium ion secondary batteries, can exhibit high battery performance.

The binder resin for a nonaqueous secondary battery positive electrode according to the present invention will be described.
The binder resin for a nonaqueous secondary battery positive electrode of the present invention is characterized by containing a (co) polymer containing a monomer unit (a) represented by the following general formula (1).

In formula (1), ^{R 1} and ^{R 2,} one of ^{R 1} and ^{R 2} is a linear or branched alkyl group having 1 to 12 carbon hydrogen or C, straight chain other is from 1 to 12 carbon atoms Or it is a branched alkyl group. When at least one of R ¹ and R ² is a linear or branched alkyl group having 1 to 12 carbon atoms, the flexibility of the finally obtained electrode is improved.

  Examples of the linear or branched alkyl group having 1 to 12 carbon atoms include a methyl group, an ethyl group, a propyl group, and an isopropyl group. Examples of the monomer unit (a) having such a structure include N-methylacrylamide, N, N-dimethylacrylamide, N-ethylacrylamide, N, N-diethylacrylamide, and N-isopropylacrylamide. Note that these may be used alone or in combination of two or more. Further, among these, N, N-dimethylacrylamide is contained in that the solubility in water is good, the flexibility of the positive electrode is improved, and the effect of improving the adhesion between the positive electrode mixture layer and the current collector is good. preferable.

  In formula (1), n is an integer of 1 to 30000000, preferably 2 or more, and more preferably 10 or more. By increasing n, preferable characteristics derived from the monomer unit (a) represented by the general formula (1) are easily developed.

The binder resin for a non-aqueous secondary battery positive electrode of the present invention has the monomer unit (a) represented by the general formula (1) as an essential component, and preferably the homopolymer is insoluble in the non-aqueous electrolyte. The (co) polymer (I) containing the monomer unit (b) is included. The binder composed of this (co) polymer (I) is referred to as binder resin (I).
The monomer unit in which the homopolymer is insoluble in the non-aqueous electrolyte means that when the monomer unit (b) as the structural unit is polymerized to form a homopolymer, the polymer is non-aqueous electrolysis. It is insoluble in the liquid. Examples of the monomer unit (b) satisfying such conditions include N-vinylacetamide (PNVA), N-vinylformamide (PNVF), acrylamide, acrylic acid, acrylate esters, and modified products thereof. In particular, PNVF, acrylic acid, and acrylamide are preferable because of their excellent electrochemical characteristics. These may be used alone or in combination.

  The amount of the monomer unit (a) represented by the general formula (1) is preferably 5 to 100% by mass, more preferably 10 to 90% by mass in the (co) polymer (I). 80% is more preferable, and 30 to 70% is most preferable. If 5 mass% or more is included, the adhesion between the positive electrode mixture layer and the current collector and the flexibility of the positive electrode are improved.

  Further, the amount of the monomer unit (b) insoluble in the non-aqueous electrolyte is preferably 0 to 95% by mass, more preferably 10 to 90% by mass in the (co) polymer (I), and 20 -85% is more preferable, and 30-70% is most preferable. If this monomer unit is included, it becomes insoluble in the non-aqueous electrolyte and can be used stably as the binder resin (I).

  The (co) polymer (I) may contain other water-soluble monomer units (c). Examples of the other water-soluble monomer unit (c) include vinyl alcohol, ethylene glycol, vinyl pyrrolidone, and modified products thereof, and these may be used alone or in combination.

  The preferred amount of the other water-soluble monomer unit (c) is preferably 0 to 40% by mass, more preferably 0 to 30% by mass, and most preferably 0 to 10% in the (co) polymer (I). preferable. If it is 40 mass% or less, the performance derived from the monomer unit (a) and the monomer unit (b) is likely to be exhibited.

  The (co) polymer (I) is obtained by polymerizing the monomer unit (a) represented by the general formula (1), which is an essential component, or preferably with the monomer unit (a). It can be obtained by copolymerizing a monomer unit (b) that is insoluble in the water electrolyte and, in some cases, a water-soluble monomer (c). The polymerization method is not particularly limited and includes general radical polymerization, controlled radical polymerization, cationic polymerization, and anionic polymerization. Among these, radical polymerization can be most easily used, and any homopolymer can be obtained by bulk polymerization, solution polymerization, emulsion polymerization, and suspension polymerization. Among these, bulk polymerization and solution polymerization are particularly preferable because a high-purity polymer is easily obtained without using an emulsifier or the like. Moreover, methods such as adiabatic polymerization, thermal polymerization, and photopolymerization can be used.

  The initiator used for the polymerization is not particularly limited as long as it can be dissolved in water. For example, 2,2′-azobis (2-methylpropionamidine) dihydrochloride, 2,2′-azobis [N- (2 -Carboxyethyl) -2-methylpropionamidine] hydrate, 2,2'-azobis {2- [1- (2-hydroxyethyl) -2-imidazolin-2-yl] propane} dihydrochloride, 2,2 ' -Azobis [2- (2-imidazolin-2-yl) propane], 2,2'-azobis {2-methyl-N- [1,1-bis (hydroxymethyl) -2-hydroxyethyl] propionamide}, etc. Common water-soluble azo compounds, water-soluble organic peroxides such as t-butyl hydroperoxide, potassium persulfate, ammonium persulfate, sodium persulfate And the like of the water-soluble inorganic peroxide. An oxidizing agent such as persulfate can also be used as a redox initiator in combination with a reducing agent such as sodium bisulfite, sodium thiosulfate, or hydrosulfite, and a polymerization accelerator such as iron sulfate.

  Also, for example, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, 1-hydroxy-cyclohexyl-phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, bis (2,4 Radical polymerization initiators such as general photopolymerization initiators such as, 6-trimethylbenzoyl) -phenylphosphine oxide are also preferably used.

  In addition, for the purpose of adjusting the molecular weight, a chain transfer agent such as a mercaptan compound, thioglycol, carbon tetrachloride, α-methylstyrene dimer, a dispersing agent or the like may be used for the polymerization.

  The mass average molecular weight of the (co) polymer (I) having the monomer unit (a) represented by the general formula (1) as an essential component is preferably 10,000 to 20 million, and 500,000 to 1500 More preferably, it is more preferably 1,000,000 to 10,000,000, and most preferably 3 million to 6,000,000. When the mass average molecular weight is within the above range, the viscosity of the binder resin is appropriate and the dispersibility of the electrode slurry becomes stable. The mass average molecular weight can be measured using gel permeation chromatography (GPC).

  The amount of the (co) polymer (I) having the monomer unit (a) represented by the general formula (1) as an essential component is 5 to 100% in a total amount of 100% by mass of the binder resin (I). % Is preferable, 10 to 100% by mass is more preferable, 30 to 98% by mass is further preferable, and 50 to 95% by mass is most preferable. If the (co) polymer (I) containing the monomer unit (a) represented by the general formula (1) as an essential component is contained in an amount of 30% by mass or more, the dispersibility of the electrode slurry is improved, and the electrode can be used. The effect of improving the flexibility and the effect of improving the adhesion between the positive electrode mixture layer and the current collector are obtained. Even if 100% by mass may be obtained, it is preferable to add other water-soluble resin (II) in an amount of 1 to 5% by mass of the total amount of the binder resin in order to improve electrode slurry stability and oxidation resistance. There is also.

  The other water-soluble binder resin (II) is obtained by (co) polymerizing at least one of the monomer units (b) and those listed as the water-soluble monomer (c).

  As described above, the binder resin for a non-aqueous secondary battery positive electrode according to the present invention includes only the binder resin (I) and includes a blend of the binder resin (I) and the binder resin (II). There is.

  The binder resin of the present invention contains a (co) polymer (I) containing the monomer unit (a) represented by the general formula (1) as an essential component as an essential component, for example, a lithium ion secondary It can use suitably for the positive electrode of a battery.

The positive electrode for a nonaqueous secondary battery of the present invention comprises a binder resin for a nonaqueous secondary battery positive electrode, a positive electrode active material, a positive electrode mixture layer containing a conductive additive, and a current collector. .
Examples of the current collector include an aluminum foil, a nickel foil, a gold foil, a silver foil, and a titanium foil, and an aluminum foil is preferred from the viewpoint of price and stability.

The positive electrode active material may be any material that can reversibly insert and remove lithium ions. For example, at least one metal selected from iron, cobalt, nickel, and manganese, and a metal composite oxide containing lithium may be used. Typical examples include LiCoO ₂ and LiMn ₂ O ₄ . Moreover, you may use the compound which has olivine structures, such as lithium iron phosphate and lithium manganese phosphate. These may be used alone or in combination of two or more.

  The positive electrode active material is used in combination with a conductive additive. The conductive auxiliary agent is preferably one that easily conducts electricity, and examples thereof include graphite, carbon black, carbon nanotube, carbon nanofiber, acetylene black, fullerene, and conductive polymer. These may be used alone or in combination of two or more.

  1-20 mass parts is preferable with respect to 100 mass parts of positive electrode active materials, and, as for the addition amount of a conductive support agent, 3-10 mass parts is more preferable. When there is less content of a conductive support agent than 1 mass part, there exists a possibility that electrode resistance cannot fully be reduced. On the other hand, when the amount is 20 parts by mass or more, the amount of the positive electrode active material is reduced, so that it is difficult to ensure the capacity.

  0.1-10 mass parts is preferable with respect to 100 mass parts of positive electrode active materials, and, as for the addition amount of binder resin, 0.3-5 mass parts is more preferable, and 0.5-3 mass parts is the most preferable. When the content of the binder resin is less than 0.1 parts by mass, there is a concern that the electrode slurry for the positive electrode is not stable and the adhesion between the electrode mixture layer and the current collector cannot be obtained sufficiently. On the other hand, when the amount exceeds 10 parts by mass, the amount of the positive electrode active material decreases, so that it is difficult to ensure the capacity.

  The binder resin may be powder or granules after drying, or may be used after being dissolved in advance as an aqueous solution having an arbitrary concentration. When mixing a plurality, they may be added sequentially or mixed in advance.

  As the solvent used in the positive electrode electrode slurry preparation step, water is preferable because it is harmless to the human body and the environment, and can be reduced in cost by omitting recovery equipment and reducing drying energy. Moreover, a small amount of an organic solvent may be contained with respect to water as long as there is no influence.

  The electrode slurry for a positive electrode is obtained by kneading and dispersing a positive electrode active material, a conductive additive, and the binder resin of the present invention in a solvent. The electrode slurry preparation step for the positive electrode is not particularly limited as long as it is a uniformly dispersible method. And a combination thereof.

  The solid content of the electrode slurry for the positive electrode is not particularly limited as long as it is well dispersed. However, depending on the type of the positive electrode active material, the amount of the conductive auxiliary agent, the type of the binder resin, and the viscosity for each amount, 50 to 70 mass. It is preferable to adjust by about%.

  The electrode is obtained by coating a positive electrode slurry on a current collector and drying. Coating method is not particularly limited, for example, bar coating method, doctor blade method, knife method, dipping method, transfer method, reverse roll method, direct roll method, gravure method, extrusion method, curtain method, brush coating method, etc. Is applied so that the thickness of the electrode layer is 0.1 to 500 μm.

  Drying only needs to be able to remove the solvent in the electrode slurry coated on the current collector, such as natural drying, low temperature air drying, heat drying, hot air drying, vacuum drying, infrared drying, far infrared drying, electron beam drying, etc. Are used alone or in combination.

  The drying temperature immediately after coating is preferably a temperature at which the content in the positive electrode slurry is less liable to flow, preferably 20 to 80 degrees, and more preferably 30 to 60 degrees. If it is 20 degree | times or more, drying time will become short, and if it is 60 degree | times or less, the binder resin can suppress the adhesive fall of the positive mix layer and an electrical power collector by uneven distribution.

  The drying temperature after drying once may be a temperature at which the content in the positive electrode slurry does not change, and is preferably 40 to 120 degrees, more preferably 60 to 100 degrees. If it is 40 degree | times or more, drying time can be shortened, and if it is 120 degree | times or less, it can suppress that the content in the electrode slurry for positive electrodes decomposes | disassembles and changes in quality.

  After drying, the electrode may be pressed as necessary. By pressing, the area of the electrode layer can be expanded and adjusted to an arbitrary thickness. In addition, the smoothness of the electrode surface and the electrode density can be increased. Examples of the pressing method include a mold press and a roll press. The pressing may be performed at room temperature, may be performed by heating, or may be performed simultaneously with drying.

  Moreover, you may cut | disconnect an electrode to arbitrary dimensions as needed. Examples of the cutting method include slitting, punching, and pressing.

  The final water content of the electrode is preferably 2000 ppm or less, and more preferably 1000 ppm. If it is 2000 ppm or less, the deterioration caused by moisture in the battery can be suppressed.

The nonaqueous secondary battery of the present invention includes the positive electrode of the present invention.
The positive electrode and the negative electrode produced as described above are arranged with a liquid-permeable separator (for example, a polyethylene or polypropylene porous film) interposed therebetween, and impregnated with a non-aqueous electrolyte solution. Thus, a non-aqueous secondary battery (laminated type, laminated type) is formed. Also, a bottomed metal casing having a structure obtained by winding a laminate composed of a positive electrode / separator having active layers formed on both sides / a negative electrode / separator having active layers formed on both sides in a roll shape (spiral shape) The cylindrical non-aqueous secondary battery is obtained by sealing the casing after the negative electrode is connected to the negative electrode terminal, the positive electrode is connected to the positive electrode terminal and impregnated with the electrolytic solution.
As the non-aqueous secondary battery of the present invention, for example, a lithium ion secondary battery is preferable.

  As the negative electrode used in the nonaqueous secondary battery of the present invention, a commonly used negative electrode can be suitably used. A negative electrode is equipped with the negative electrode active material, the negative electrode mixture layer containing the conductive support agent as needed, and the binder resin for negative electrodes, and the negative electrode electrical power collector. Examples of the negative electrode current collector include a copper foil, a nickel foil, a gold foil, a silver foil, and a titanium foil. From the viewpoint of price and stability, a copper foil is preferable.

  The negative electrode active material only needs to be able to reversibly remove and insert lithium ions. For example, carbon materials such as graphite, amorphous carbon, carbon fiber, coke and activated carbon, metals such as silicon, tin, and silver, or these The oxide is preferably used. These may be used alone or in combination of two or more.

  The negative electrode active material can also be used in combination with a conductive additive. The conductive auxiliary agent is preferably one that easily conducts electricity, and examples thereof include graphite, carbon black, carbon nanotube, carbon nanofiber, acetylene black, fullerene, and conductive polymer. These may be used alone or in combination of two or more.

  0.1-20 mass parts is preferable with respect to 100 mass parts of negative electrode active materials, and, as for the addition amount in the case of adding a conductive support agent, 1-10 mass parts is more preferable. When there is less content of a conductive support agent than 0.1 mass part, there exists a possibility that the reduction effect of electrode resistance may not fully be acquired. On the other hand, when the amount is 20 parts by mass or more, the amount of the negative electrode active material is reduced, so that it is difficult to ensure the capacity.

  The negative electrode binder resin is preferably water-based, and for example, general materials such as CMC and SBR, and other water-soluble binders mentioned as other water-soluble binder resins (II) can be used. These can be used alone or in combination.

  0.1-10 mass parts is preferable with respect to 100 mass parts of active materials, as for the addition amount of binder resin for negative electrodes, 0.3-5 mass parts is more preferable, and 0.5-3 mass parts is the most preferable. When the content of the binder resin for the negative electrode is less than 0.1 parts by mass, there is a concern that the electrode slurry for the negative electrode is not stable and the adhesion between the electrode mixture layer and the current collector cannot be obtained sufficiently. . On the other hand, when the amount exceeds 10 parts by mass, the amount of the negative electrode active material decreases, so that it is difficult to ensure the capacity.

  As the solvent used in the electrode slurry preparation step for the negative electrode, water is preferable because it is harmless to the human body and the environment and can be reduced in cost by omitting the recovery equipment and reducing the drying energy. Moreover, a small amount of an organic solvent may be contained with respect to water as long as there is no influence.

  The electrode slurry for negative electrode is obtained by kneading and dispersing a negative electrode active material, a conductive additive, and a binder resin for negative electrode in a solvent. The electrode slurry preparation step for the negative electrode is not particularly limited as long as it is a uniformly dispersible method. For example, the negative electrode slurry is kneaded by various dispersers such as a stirrer, a revolving stirrer, a mixer, a planetary mixer, a homogenizer, a ball mill, a sand mill, and a roll mill. And a combination thereof.

  The solid content of the electrode slurry for the negative electrode is not particularly limited as long as it is well dispersed, but depending on the type of the negative electrode active material, the amount of the conductive auxiliary agent, the type of the binder resin for the negative electrode, and the viscosity for each amount. It is preferable to prepare at about 70% by mass.

As the electrolytic solution, for example, in the case of a lithium ion secondary battery, a solution obtained by dissolving a lithium salt as an electrolyte in a non-aqueous organic solvent at a concentration of about 1M is used.
Examples of the lithium salt, for _{example, LiClO 4, LiBF 4, LiI} , LiPF 6, LiCF 3 SO 3, LiCF 3 CO 2, LiAsF 6, LiSbF 6, LiAlCl 4, LiCl, LiBr, LiB (C 2 H 5) 4 , LiCH ₃ SO ₃ , LiC ₄ F ₉ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, Li [(CO ₂ ) ₂ ] ₂ B.

  Examples of the non-aqueous organic solvent include carbonates such as propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate; lactones such as γ-butyrolactone; trimethoxymethane, 1,2-dimethoxyethane Ethers such as diethyl ether, 2-ethoxyethane, tetrahydrofuran and 2-methyltetrahydrofuran; sulfoxides such as dimethyl sulfoxide; oxolanes such as 1,3-dioxolane and 4-methyl-1,3-dioxolane; acetonitrile, nitromethane , Nitrogen-containing compounds such as NMP; esters such as methyl formate, methyl acetate, butyl acetate, methyl propionate, ethyl propionate, phosphate triester; diglyme, triglyme, Glymes such as traglime; ketones such as acetone, diethyl ketone, methyl ethyl ketone, methyl isobutyl ketone; sulfones such as sulfolane; oxazolidinones such as 3-methyl-2-oxazolidinone; 1,3-propane sultone, 4-butane sultone, Examples include sultone such as naphtha sultone. The said electrolyte solution may be used individually by 1 type, and may use 2 or more types together.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further in detail, a following example does not limit the scope of the present invention.

[Manufacture of binder resin]
<Production Example 1: N, N′-dimethylacrylamide polymer (I-1)>
A monomer aqueous solution was prepared by mixing 60 parts by mass of N, N′-dimethylacrylamide (manufactured by Kojin Co., Ltd., hereinafter the same) as the monomer unit (a) with respect to 40 parts by mass of deionized water. In this, 0.018 mass part initiator (Darocur 4265, Ciba Japan Co., Ltd. product) was melt | dissolved, and nitrogen bubbling was carried out for 30 minutes. This was poured into a 1 mm-thick cell made of silicon rubber on a pet film, and polymerized with a chemical lamp of 1 mW / cm ² for 1 hour. The periphery of the obtained polymer was cut off, cut into small pieces, dried at room temperature, and then dried overnight in a 40 degree vacuum drier to obtain N, N′-dimethylacrylamide polymer (I-1) (PDMA). It was.

<Production Example 2: N, N′-isopropylacrylamide polymer (I-2)>
A monomer solution was prepared by mixing 22 parts by mass of N, N′-isopropylacrylamide (manufactured by Tokyo Chemical Industry Co., Ltd.) as a monomer unit (a) with respect to 74 parts by mass of deionized water and 4 parts by mass of ethanol. . In this, 0.007 mass part initiator (Darocur 4265, Ciba Japan Co., Ltd. product) was melt | dissolved, and nitrogen bubbling was carried out for 30 minutes. This was poured into a 1 mm-thick cell made of silicon rubber on a PET film and polymerized with a chemical lamp of 1 mW / cm ² for 3 hours. The surroundings were cut off, finely cut, dried at room temperature, and then dried overnight in a 40 degree vacuum drier to obtain N, N′-dimethylacrylamide polymer (I-2) (PNIPAM).

<Production Example 3: N-vinylformamide polymer (II-1)>
A monomer aqueous solution in which 30 parts by mass of N-vinylformamide was mixed with 70 parts by mass of deionized water was adjusted to pH = 6.3 with phosphoric acid to obtain a monomer adjustment solution. After cooling this monomer control liquid to 5 degreeC, it put into the heat insulation reaction container which attached the thermometer, and nitrogen aeration was performed for 15 minutes. Thereafter, 0.4 part by mass of a 12% by mass aqueous solution of 4,4′-azobis (4-cyanovaleric acid) (manufactured by Wako Pure Chemical Industries, Ltd., “V-501”) was added, and then t-butyl hydro Polymerization was carried out by adding 0.1 parts by weight of a 10% by weight aqueous peroxide solution and a 10% by weight aqueous sodium hydrogen sulfite solution. After the internal temperature exceeded the peak, it was further aged for 1 hour, the gel was taken out and pulverized with a meat chopper, dried at 60 ° C. for 10 hours, the obtained solid was pulverized, and the N-vinylformamide polymer (II-1 ) (PNVF) was obtained.

<Production Example 4: Acrylamide polymer (II-2)>
A monomer aqueous solution was prepared by mixing 33.3 parts by mass of acrylamide (manufactured by Wako Co., Ltd., the same applies hereinafter) with 33.7 parts by mass of deionized water. To this, 0.01 parts by mass of an initiator (Darocur 4265, manufactured by Ciba Japan Co., Ltd.) was dissolved and subjected to nitrogen bubbling for 30 minutes. This was poured into a 1 mm-thick cell made of silicon rubber on a pet film, and polymerized with a chemical lamp of 1 mW / cm ² for 1 hour. The surroundings were cut off, finely cut, dried at room temperature, and then dried overnight in a 40 degree vacuum drier to obtain acrylamide polymer (II-2) (PAAm).

<Production Example 5: DMA-NVF copolymer (I-3)>
A monomer aqueous solution was prepared by adding 70% by mass of N, N′-dimethylacrylamide and 30% by mass of N-vinylformamide, and mixing it with 40 parts by mass of deionized water. In this, 0.018 mass part initiator (Darocur 4265, Ciba Japan Co., Ltd. product) was melt | dissolved, and nitrogen bubbling was carried out for 30 minutes. This was poured into a 1 mm-thick cell made of silicon rubber on a pet film, and polymerized with a chemical lamp of 1 mW / cm ² for 1 hour. This was cut off at the periphery, finely cut and dried at room temperature, and then dried overnight in a 40 degree vacuum drier to obtain a DMA-NVF polymer (I-3).

<Production Example 6: DMA-NVF copolymer (I-4)>
N, N'-dimethylacrylamide 50 mass% and N-vinylformamide 50 mass% were combined to make 60 mass parts, and a monomer aqueous solution mixed with 40 mass parts of deionized water was prepared. In this, 0.018 mass part initiator (Darocur 4265, Ciba Japan Co., Ltd. product) was melt | dissolved, and nitrogen bubbling was carried out for 30 minutes. This was poured into a 1 mm-thick cell made of silicon rubber on a pet film, and polymerized with a chemical lamp of 1 mW / cm ² for 1 hour. This was cut off at the periphery, finely cut and dried at room temperature, and then dried overnight in a 40 degree vacuum drier to obtain a DMA-NVF polymer (I-4).

<Production Example 7: DMA-NVF copolymer (I-5)>
N, N′-dimethylacrylamide 50 mass% and N-vinylformamide 50 mass% were combined to make 100 parts by mass to prepare a mixed monomer aqueous solution. In this, 0.03 mass part initiator (Darocur 4265, Ciba Japan Co., Ltd. product) was melt | dissolved, and nitrogen bubbling was carried out for 30 minutes. This was poured into a 1 mm-thick cell made of silicon rubber on a pet film, and polymerized with a chemical lamp of 1 mW / cm ² for 1 hour. This was cut off at the periphery, finely cut and dried at room temperature, and then dried overnight in a 40 degree vacuum drier to obtain a DMA-NVF polymer (I-5).

<Production Example 8: DMA-NVF copolymer (I-6)>
A monomer aqueous solution was prepared by mixing 30 parts by mass of N, N′-dimethylacrylamide and 70% by mass of N-vinylformamide to 60 parts by mass and mixing with 40 parts by mass of deionized water. In this, 0.018 mass part initiator (Darocur 4265, Ciba Japan Co., Ltd. product) was melt | dissolved, and nitrogen bubbling was carried out for 30 minutes. This was poured into a 1 mm-thick cell made of silicon rubber on a pet film, and polymerized with a chemical lamp of 1 mW / cm ² for 1 hour. This was cut off at the periphery, finely cut and dried at room temperature, and then dried overnight in a 40 degree vacuum drier to obtain a DMA-NVF polymer (I-6).

<Production Example 9: DMA-NVF copolymer (I-7)>
A monomer aqueous solution was prepared by adding 10% by mass of N, N′-dimethylacrylamide and 90% by mass of N-vinylformamide to 60 parts by mass and mixing with 40 parts by mass of deionized water. In this, 0.018 mass part initiator (Darocur 4265, Ciba Japan Co., Ltd. product) was melt | dissolved, and nitrogen bubbling was carried out for 30 minutes. This was poured into a 1 mm-thick cell made of silicon rubber on a pet film, and polymerized with a chemical lamp of 1 mW / cm ² for 1 hour. This was cut off at the periphery, finely cut and dried at room temperature, and then dried overnight in a 40 degree vacuum drier to obtain a DMA-NVF polymer (I-7).

<Production Example 10: DMA-NVF copolymer (I-8)>
N, N′-dimethylacrylamide 5 mass% and N-vinylformamide 95 mass% were combined to make 100 mass parts to prepare an aqueous monomer solution. 0.1 parts by mass of initiator (perhexyl PV) was dissolved in this, and nitrogen bubbling was performed for 30 minutes. This was poured into a 1 mm-thick cell made of a glass plate with a polyethylene film attached, and polymerized in a 60-degree hot water bath for 1 hour. This was cut off at the periphery, finely cut and dried at room temperature, and then dried overnight in a 40 degree vacuum drier to obtain a DMA-NVF polymer (I-8).

<Production Example 11: DMA-AAm copolymer (I-9)>
N, N'-dimethylacrylamide 70 mass% and acrylamide 30 mass% were made into 60 mass parts, and the monomer aqueous solution mixed with 40 mass parts of deionized water was produced. In this, 0.018 mass part initiator (Darocur 4265, Ciba Japan Co., Ltd. product) was melt | dissolved, and nitrogen bubbling was carried out for 30 minutes. This was poured into a 1 mm-thick cell made of silicon rubber on a pet film, and polymerized with a chemical lamp of 1 mW / cm ² for 1 hour. This was cut off at the periphery, finely cut and dried at room temperature, and then dried overnight in a 40 degree vacuum drier to obtain a DMA-AAm polymer (I-9).

<Production Example 12: DMA-AAm copolymer (I-10)>
N, N'-dimethylacrylamide 50 mass% and acrylamide 50 mass% were combined to make 10 mass parts, and a monomer aqueous solution mixed with 100 mass parts of deionized water was prepared. To this, 0.01 parts by mass of initiator (perhexyl PV) was dissolved and nitrogen bubbling was performed for 30 minutes. This was poured into a 1 mm-thick cell made of a glass plate with a polyethylene film attached, and polymerized in a 60-degree hot water bath for 1 hour. This was cut off at the periphery, finely cut and dried at room temperature, and then dried overnight in a 40 degree vacuum drier to obtain a DMA-AAm polymer (I-10).

<Production Example 13: DMA-AA copolymer (I-11)>
In a four-necked round bottom flask, a monomer aqueous solution in which 58 parts by mass of N, N'-dimethylacrylamide and 42 parts by mass of acrylic acid are combined to make 10 parts by mass and mixed with 90 parts by mass of deionized water is prepared and stirred. Wings and cooling pipes were connected. 0.4 mass part sodium formate was melt | dissolved in this, and nitrogen bubbling was carried out for 30 minutes, stirring. The temperature was raised to 50 degrees, 0.8 parts by mass of a 10% initiator (V-50, manufactured by Wako Pharmaceutical Co., Ltd.) aqueous solution was added and polymerized for 3 hours, and again 0.8 parts by mass of a 10% initiator. (V-50) Aqueous solution was added and polymerized for 3 hours. The resulting polymerization solution was cooled and precipitated into a large amount of methyl ethyl ketone. This was dried overnight in a 40 degree vacuum drier to obtain a DMA-AAm polymer (I-11).

<Production Example 14: DMA-AA copolymer (I-12)>
In a four-necked round bottom flask, a monomer aqueous solution prepared by mixing 26 parts by mass of N, N′-dimethylacrylamide and 74 parts by mass of acrylic acid to 10 parts by mass and mixing with 90 parts by mass of deionized water is prepared and stirred. Wings and cooling pipes were connected. 0.4 mass part sodium formate was melt | dissolved in this, and nitrogen bubbling was carried out for 30 minutes, stirring. The temperature was raised to 50 degrees, 0.8 parts by mass of a 10% initiator (V-50, manufactured by Wako Pharmaceutical Co., Ltd.) aqueous solution was added and polymerized for 3 hours, and again 0.8 parts by mass of a 10% initiator. (V-50) Aqueous solution was added and polymerized for 3 hours. The resulting polymerization solution was cooled and precipitated into a large amount of methyl ethyl ketone. This was dried overnight in a 40 degree vacuum drier to obtain a DMA-AAm polymer (I-12).

<Production Example 15: DEA-NVF copolymer (I-13)>
N, N′-diethylacrylamide 30 mass% and N-vinylformamide 70 mass% were combined to make 60 mass parts, and a monomer aqueous solution mixed with 40 mass parts of deionized water was prepared. In this, 0.018 mass part initiator (Darocur 4265, Ciba Japan Co., Ltd. product) was melt | dissolved, and nitrogen bubbling was carried out for 30 minutes. This was poured into a 1 mm-thick cell made of silicon rubber on a pet film, and polymerized with a chemical lamp of 1 mW / cm ² for 1 hour. This was cut off at the periphery, finely cut, dried at room temperature, and then dried overnight in a 40 degree vacuum drier to obtain a DEA-NVF polymer (I-13).

<Production Example 16: DEA-NVF copolymer (I-14)>
A monomer aqueous solution was prepared by adding 70% by mass of N, N′-diethylacrylamide and 30% by mass of N-vinylformamide, and mixing it with 40 parts by mass of deionized water. In this, 0.018 mass part initiator (Darocur 4265, Ciba Japan Co., Ltd. product) was melt | dissolved, and nitrogen bubbling was carried out for 30 minutes. This was poured into a 1 mm-thick cell made of silicon rubber on a pet film, and polymerized with a chemical lamp of 1 mW / cm ² for 1 hour. This was cut off at the periphery, finely cut, dried at room temperature, and then dried overnight in a 40 degree vacuum drier to obtain a DEA-NVF polymer (I-14).

(Measurement of molecular weight of polymer)
The molecular weight of the produced (co) polymer was measured by the following method.
GPC manufactured by Waters, Shodex OHpac SB-807HQ was used for the column, acetonitrile / water = 10/90 (containing 0.1N sodium nitrate) as a solvent, measurement at 40 ° C., flow rate 0.5 ml / min. The molecular weight in terms of poly N-vinylformamide detected by an IR detector and normalized by the molecular weight in terms of viscosity was calculated.

[Example 1]
<Preparation of electrode slurry for positive electrode>
As a binder resin, 0.2 g of N, N′-dimethylacrylamide polymer (I-1) and 3.56 g of water were mixed with a self-revolving mixer (manufactured by Thinky, “Awatori Netaro”, the same applies hereinafter). The mixture was kneaded and dissolved under the conditions of rotation at 1000 rpm and revolution at 2000 rpm. After further adding 10.0 g of lithium cobaltate (Nippon Kagaku Kogyo Co., Ltd., “Cellseed C-5H”, the same applies below) and 0.5 g of acetylene black (Electrochemical Co., Ltd., the same applies below) and kneading. Then, by adding water and kneading to a coatable viscosity, a positive electrode slurry was obtained.

<Preparation of positive electrode>
The obtained electrode slurry for positive electrode was uniformly applied to a current collector (aluminum foil, thickness 20 μm) by a doctor blade method and dried at room temperature for 2 hours. Furthermore, it dried under reduced pressure at 0.6 kPa and 60 degreeC with the vacuum dryer for 12 hours, and obtained the positive electrode with which the 80-micrometer-thick mixture layer was formed on the electrical power collector (aluminum foil).
The obtained electrode was evaluated for the adhesion between the positive electrode mixture layer and the current collector and the flexibility of the positive electrode by the following methods. The results are shown in Table 1.

(Electrode adhesion evaluation)
The adhesion (electrode adhesion) between the positive electrode mixture layer and the current collector was evaluated by the peel strength measured by a peel test performed under the following conditions.
The electrode was made into a 20 mm wide test piece and bonded to a polycarbonate plate with an adhesive through a nip roll. In the Tensilon tensile strength test, a 180 ° peel test was performed using a 10N load cell at a tensile speed of 1 cm / min.
The peel strength between the electrode and the current collector was measured with five test pieces, the average of the peel strength in the latter half excluding the portion where peeling started was determined, and the 180 ° peel strength (N / cm) was calculated from this.

(Flexibility evaluation of positive electrode)
The flexibility of the positive electrode is determined according to JIS K-5600-5-1 (Paint General Test Method Bending Resistance (Cylindrical Mandrel Method)) under the following conditions. It was evaluated by the flexibility.
The electrode was cut into 3 cm × 5 cm and pressed with a press roll to adjust the electrode density to 3 g / cm ³ to obtain a test piece. The test piece was placed so that the aluminum foil surface was on the mandrel side, one side of the test piece was fixed with tape, bent, and the state of the coating film was visually observed. Evaluation was made while reducing the diameter of the mandrel as follows.
Mandrel diameter: 32mm, 25mm, 16mm, 10mm, 8mm, 6mm, 5mm, 3mm, 2mm
○: No change in electrode on the bent surface Δ: Horizontal streaks were observed on the electrode on the bent surface ×: Cracks and cracks in the electrode were observed on the bent surface About three test pieces The minimum diameter of the mandrel with which the total value of the result was 4 or more was defined as flexibility (mm), where ◯ was 2, 1 was 1, and x was 0.

[Example 2]
In a container, 10.0 g of lithium cobaltate and 0.5 g of acetylene black were weighed and stirred with a self-revolving mixer. While adding 6.67 g of 3% by weight aqueous solution prepared by dissolving N, N′-dimethylacrylamide polymer (I-1) in deionized water as a binder resin in several portions, a revolving mixer And stirred. Furthermore, the electrode slurry for positive electrodes was obtained by adding water and kneading to the viscosity which can be applied. A positive electrode was obtained in the same manner as in Example 1 except that the drying conditions immediately after application were 40 ° C. and 30 minutes.
The obtained electrode was evaluated in the same manner as in Example 1 for the adhesion between the positive electrode mixture layer and the current collector and the flexibility of the positive electrode. The results are shown in Table 1.

[Example 3]
A positive electrode slurry and a positive electrode were obtained in the same manner as in Example 1 except that the drying conditions immediately after application were 80 ° C. and 30 minutes.
The obtained electrode was evaluated in the same manner as in Example 1 for the adhesion between the positive electrode mixture layer and the current collector and the flexibility of the positive electrode. The results are shown in Table 1.

[Example 4]
A positive electrode slurry and a positive electrode were obtained in the same manner as in Example 1 except that the amount of the binder resin was changed to 0.15 g.
The obtained electrode was evaluated in the same manner as in Example 1 for the adhesion between the positive electrode mixture layer and the current collector and the flexibility of the positive electrode. The results are shown in Table 1.

[Example 5]
A positive electrode slurry and a positive electrode were obtained in the same manner as in Example 1 except that the amount of the binder resin was 0.15 g and the drying conditions immediately after coating were 40 ° C. and 30 minutes.
The obtained electrode was evaluated in the same manner as in Example 1 for the adhesion between the positive electrode mixture layer and the current collector and the flexibility of the positive electrode. The results are shown in Table 1.

[Example 6]
A positive electrode slurry and a positive electrode were obtained in the same manner as in Example 1 except that the amount of the binder resin was 0.1 g.
The obtained electrode was evaluated in the same manner as in Example 1 for the adhesion between the positive electrode mixture layer and the current collector and the flexibility of the positive electrode. The results are shown in Table 1.

[Example 7]
A positive electrode slurry and a positive electrode were obtained in the same manner as in Example 1 except that the amount of the binder resin was 0.1 g, and the drying conditions immediately after coating were 40 ° C. and 30 minutes.
The obtained electrode was evaluated in the same manner as in Example 1 for the adhesion between the positive electrode mixture layer and the current collector and the flexibility of the positive electrode. The results are shown in Table 1.

[Example 8]
As binder resin, the same procedure as in Example 2 was performed except that 6.67 g of a 3% by mass aqueous solution of N, N′-isopropylacrylamide polymer (I-2) was used and the drying condition immediately after coating was set at room temperature for 2 hours. A positive electrode slurry and a positive electrode were obtained.
The obtained electrode was evaluated in the same manner as in Example 1 for the adhesion between the positive electrode mixture layer and the current collector and the flexibility of the positive electrode. The results are shown in Table 1.

[Example 9]
Except that 0.18 g of N, N′-dimethylacrylamide polymer (I-1) and 0.02 g of N-vinylformamide polymer (II-1) were used as the binder resin, A positive electrode slurry and a positive electrode were obtained.
The obtained electrode was evaluated in the same manner as in Example 1 for the adhesion between the positive electrode mixture layer and the current collector and the flexibility of the positive electrode. The results are shown in Table 1.

[Example 10]
Except for using 0.15 g of N, N′-dimethylacrylamide polymer (I-1) and 0.05 g of N-vinylformamide polymer (II-1) as the binder resin, A positive electrode slurry and a positive electrode were obtained.
The obtained electrode was evaluated in the same manner as in Example 1 for the adhesion between the positive electrode mixture layer and the current collector and the flexibility of the positive electrode. The results are shown in Table 1.

[Example 11]
As the binder resin, in the same manner as in Example 1, except that 0.1 g of N, N′-dimethylacrylamide polymer (I-1) and 0.1 g of N-vinylformamide polymer (II-1) were used, A positive electrode slurry and a positive electrode were obtained.
The obtained electrode was evaluated in the same manner as in Example 1 for the adhesion between the positive electrode mixture layer and the current collector and the flexibility of the positive electrode. The results are shown in Table 1.

[Example 12]
Except that 0.05 g of N, N′-dimethylacrylamide polymer (I-1) and 0.15 g of N-vinylformamide polymer (II-1) were used as the binder resin, A positive electrode slurry and a positive electrode were obtained.
The obtained electrode was evaluated in the same manner as in Example 1 for the adhesion between the positive electrode mixture layer and the current collector and the flexibility of the positive electrode. The results are shown in Table 1.

[Example 13]
Except that 0.02 g of N, N′-dimethylacrylamide polymer (I-1) and 0.18 g of N-vinylformamide polymer (II-1) were used as the binder resin, A positive electrode slurry and a positive electrode were obtained.
The obtained electrode was evaluated in the same manner as in Example 1 for the adhesion between the positive electrode mixture layer and the current collector and the flexibility of the positive electrode. The results are shown in Table 1.

[Example 14]
Except for using 0.01 g of N, N′-dimethylacrylamide polymer (I-1) and 0.19 g of N-vinylformamide polymer (II-1) as the binder resin, the same as in Example 1, A positive electrode slurry and a positive electrode were obtained.
The obtained electrode was evaluated in the same manner as in Example 1 for the adhesion between the positive electrode mixture layer and the current collector and the flexibility of the positive electrode. The results are shown in Table 1.

[Example 15]
As the binder resin, 4.67 g of a 3% by mass aqueous solution of N, N′-dimethylacrylamide polymer (I-1) and 2.0 g of a 3% by mass aqueous solution of N-vinylformamide polymer (II-2) were used. A positive electrode slurry and a positive electrode were obtained in the same manner as Example 2 except for the above.
The obtained electrode was evaluated in the same manner as in Example 1 for the adhesion between the positive electrode mixture layer and the current collector and the flexibility of the positive electrode. The results are shown in Table 1.

[Example 16]
A positive electrode slurry and a positive electrode were obtained in the same manner as in Example 2 except that 6.67 g of a 3% by mass aqueous solution of DMA-NVF copolymer (I-3) was used as the binder resin.
The obtained electrode was evaluated in the same manner as in Example 1 for the adhesion between the positive electrode mixture layer and the current collector and the flexibility of the positive electrode. The results are shown in Table 1.

[Example 17]
A positive electrode slurry and a positive electrode were obtained in the same manner as in Example 2 except that 5.0 g of a 3% by mass aqueous solution of DMA-NVF copolymer (I-3) was used as the binder resin.
The obtained electrode was evaluated in the same manner as in Example 1 for the adhesion between the positive electrode mixture layer and the current collector and the flexibility of the positive electrode. The results are shown in Table 1.

[Example 18]
A positive electrode slurry and a positive electrode were obtained in the same manner as in Example 2 except that 3.33 g of a 3% by mass aqueous solution of DMA-NVF copolymer (I-3) was used as the binder resin.
The obtained electrode was evaluated in the same manner as in Example 1 for the adhesion between the positive electrode mixture layer and the current collector and the flexibility of the positive electrode. The results are shown in Table 1.

[Example 19]
A positive electrode slurry and a positive electrode were obtained in the same manner as in Example 2 except that 6.67 g of a 3% by mass aqueous solution of DMA-NVF copolymer (I-4) was used as the binder resin.
The obtained electrode was evaluated in the same manner as in Example 1 for the adhesion between the positive electrode mixture layer and the current collector and the flexibility of the positive electrode. The results are shown in Table 1.

[Example 20]
A positive electrode slurry and a positive electrode were obtained in the same manner as in Example 2 except that 5.0 g of a 3% by mass aqueous solution of DMA-NVF copolymer (I-4) was used as the binder resin.
The obtained electrode was evaluated in the same manner as in Example 1 for the adhesion between the positive electrode mixture layer and the current collector and the flexibility of the positive electrode. The results are shown in Table 1.

[Example 21]
A positive electrode slurry and a positive electrode were obtained in the same manner as in Example 2 except that 3.33 g of a 3% by mass aqueous solution of DMA-NVF copolymer (I-4) was used as the binder resin.
The obtained electrode was evaluated in the same manner as in Example 1 for the adhesion between the positive electrode mixture layer and the current collector and the flexibility of the positive electrode. The results are shown in Table 1.

[Example 22]
A positive electrode slurry and a positive electrode were obtained in the same manner as in Example 2 except that 6.67 g of a 3% by mass aqueous solution of DMA-NVF copolymer (I-5) was used as the binder resin.
The obtained electrode was evaluated in the same manner as in Example 1 for the adhesion between the positive electrode mixture layer and the current collector and the flexibility of the positive electrode. The results are shown in Table 1.

[Example 23]
A positive electrode slurry and a positive electrode were obtained in the same manner as in Example 2 except that 5.0 g of a 3% by mass aqueous solution of DMA-NVF copolymer (I-5) was used as the binder resin.
The obtained electrode was evaluated in the same manner as in Example 1 for the adhesion between the positive electrode mixture layer and the current collector and the flexibility of the positive electrode. The results are shown in Table 1.

[Example 24]
A positive electrode slurry and a positive electrode were obtained in the same manner as in Example 2 except that 3.33 g of a 3% by mass aqueous solution of DMA-NVF copolymer (I-5) was used as the binder resin.
The obtained electrode was evaluated in the same manner as in Example 1 for the adhesion between the positive electrode mixture layer and the current collector and the flexibility of the positive electrode. The results are shown in Table 1.

[Example 25]
A positive electrode slurry and a positive electrode were obtained in the same manner as in Example 1 except that 0.2 g of DMA-NVF copolymer (I-6) was used as the binder resin.
The obtained electrode was evaluated in the same manner as in Example 1 for the adhesion between the positive electrode mixture layer and the current collector and the flexibility of the positive electrode. The results are shown in Table 1.

[Example 26]
A positive electrode slurry and a positive electrode were obtained in the same manner as in Example 1 except that 0.2 g of DMA-NVF copolymer (I-7) was used as the binder resin.
The obtained electrode was evaluated in the same manner as in Example 1 for the adhesion between the positive electrode mixture layer and the current collector and the flexibility of the positive electrode. The results are shown in Table 1.

[Example 27]
A positive electrode slurry and a positive electrode were obtained in the same manner as in Example 2 except that 6.67 g of a 3% by mass aqueous solution of DMA-NVF copolymer (I-8) was used as the binder resin.
The obtained electrode was evaluated in the same manner as in Example 1 for the adhesion between the positive electrode mixture layer and the current collector and the flexibility of the positive electrode. The results are shown in Table 1.

[Example 28]
A positive electrode slurry and a positive electrode were obtained in the same manner as in Example 1 except that 0.2 g of DMA-AAm copolymer (I-9) was used as the binder resin.
The obtained electrode was evaluated in the same manner as in Example 1 for the adhesion between the positive electrode mixture layer and the current collector and the flexibility of the positive electrode. The results are shown in Table 1.

[Example 29]
A positive electrode slurry and a positive electrode were obtained in the same manner as in Example 2 except that 6.67 g of a 3% by mass aqueous solution of DMA-AAm copolymer (I-10) was used as the binder resin.
The obtained electrode was evaluated in the same manner as in Example 1 for the adhesion between the positive electrode mixture layer and the current collector and the flexibility of the positive electrode. The results are shown in Table 1.

[Example 30]
A positive electrode slurry and a positive electrode were obtained in the same manner as in Example 2 except that 6.67 g of a 3% by mass aqueous solution of DMA-AA copolymer (I-11) was used as the binder resin.
The obtained electrode was evaluated in the same manner as in Example 1 for the adhesion between the positive electrode mixture layer and the current collector and the flexibility of the positive electrode. The results are shown in Table 1.

[Example 31]
A positive electrode slurry and a positive electrode were obtained in the same manner as in Example 2 except that 6.67 g of a 3% by mass aqueous solution of DMA-AA copolymer (I-12) was used as the binder resin.
The obtained electrode was evaluated in the same manner as in Example 1 for the adhesion between the positive electrode mixture layer and the current collector and the flexibility of the positive electrode. The results are shown in Table 1.

[Example 32]
A positive electrode slurry and a positive electrode were obtained in the same manner as in Example 2 except that 6.67 g of a 3% by mass aqueous solution of DEA-NVF copolymer (I-13) was used as the binder resin.
The obtained electrode was evaluated in the same manner as in Example 1 for the adhesion between the positive electrode mixture layer and the current collector and the flexibility of the positive electrode. The results are shown in Table 1.

[Example 33]
As a binder resin, a positive electrode was used in the same manner as in Example 2 except that 6.67 g of a 3% by mass aqueous solution of DEA-NVF copolymer (I-14) was used and the drying conditions immediately after coating were set at 80 ° C. for 30 minutes. An electrode slurry and a positive electrode were obtained.
The obtained electrode was evaluated in the same manner as in Example 1 for the adhesion between the positive electrode mixture layer and the current collector and the flexibility of the positive electrode. The results are shown in Table 1.

The abbreviations in Table 1 mean the following.
LCO: Lithium cobaltate AB: Acetylene black BP: Binder resin

As apparent from Table 1, when the binder resin (I-1 to 2) containing the polymer having the monomer unit (a) represented by the general formula (1) is used, the positive electrode mixture layer and The positive electrode excellent in the adhesiveness with a collector and the flexibility of a positive electrode was obtained (Examples 1-15). In particular, Examples 1 to 1 using 10% by mass or more of the binder resin (I-1 to 2) containing the polymer having the monomer unit (a) represented by the general formula (1) in the binder resin. Nos. 13 and 15 were excellent in the flexibility of the positive electrode while maintaining the adhesion between the positive electrode mixture layer and the current collector.
Among these, the positive electrodes obtained in Examples 1 to 7 and 9 to 15 using the binder resin (I-1) are particularly excellent in the adhesion between the positive electrode mixture layer and the current collector and the flexibility of the positive electrode. It was excellent.
Moreover, when binder resin (I-3-14) containing the (co) polymer which has the monomer unit (a) represented by the said General formula (1) is used, a positive mix layer and an electrical power collector A positive electrode having excellent adhesion with the electrode and flexibility of the positive electrode was obtained. Furthermore, since the dispersion stability of the positive electrode slurry is good and the adhesion between the positive electrode mixture layer and the current collector is high, the amount of the binder resin in the positive electrode can be reduced (Examples 4 and 5). 6, 7, 17, 18, 20, 21, 23, 24). Thereby, the density of the positive electrode active material could be increased.
In addition, by using the binder resin of the present invention, adhesion and flexibility without using CMC that is uneasy about quality stability and latex binder resin that is disadvantageous for storage and transportation and low in oxidation resistance. The positive electrode which was excellent in this was able to be produced.

  The present invention is a binder resin capable of producing a positive electrode excellent in both the adhesion between the positive electrode mixture layer and the current collector and the flexibility of the positive electrode using only water that is harmless to the environment and the human body. In addition, the adhesion between the positive electrode mixture layer and the current collector can be expressed with a small amount of use, and the flexibility of the positive electrode is also excellent, so it is very useful when producing high capacity positive electrodes. It is. Moreover, the produced positive electrode can be used suitably for a non-aqueous secondary battery, especially a lithium ion secondary battery, and is extremely useful industrially.

Claims (3)

Binder resin for non-aqueous secondary battery positive electrode containing the (co) polymer containing the monomer unit (a) represented by following General formula (1).

(In the formula (1), ^{R 1} and ^{R 2,} one of ^{R 1} and ^{R 2} is a linear or branched alkyl group having 1 to 12 carbon hydrogen or C, straight other is from 1 to 12 carbon atoms (It is a chain or branched alkyl group. N is an integer of 1 to 30000000.)   The positive electrode for non-aqueous secondary batteries comprised from the binder resin of Claim 1, the conductive support agent, the positive mix layer containing a positive electrode active material, and a collector.   A non-aqueous secondary battery comprising the positive electrode for a non-aqueous secondary battery according to claim 2.