JP2015022956A - Slurry for power storage device, power storage device electrode, separator and power storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide slurry for a power storage device capable of forming a layer having excellent adhesion to a current collector and a separator and manufacturing a power storage device having excellent charge/discharge characteristics.SOLUTION: Disclosed is slurry for a power storage device which contains 1 to 10 pts.mass of a water-soluble polymer (A) relative to 100 pts.mass of an active material. The proportion of repeating units derived from (meth)acrylamide contained in 100 pts.mass of the water-soluble polymer (A) is 40 to 100 pts.mass.

Description

  The present invention relates to a slurry for an electricity storage device, an electricity storage device electrode comprising a layer produced by applying and drying the slurry, a separator comprising a layer produced by applying and drying the slurry, and the electrode and the electrode The present invention relates to an electricity storage device including at least one of separators.

  A positive electrode and a negative electrode (hereinafter, also referred to as “electrode”) used in an electricity storage device are formed by applying a mixture of an active material and a binder to a surface of a current collector and drying the active material layer on the surface of the current collector. (See, for example, Patent Document 1). In recent years, a technique has also been proposed in which a mixture of a filler and a binder is applied to the separator surface and dried to form a protective film that can withstand dendrites on the separator surface. Thus, in the field of power storage devices, it is common to provide a layer containing an active material or filler on the surface of an electrode or a separator (see, for example, Patent Document 2).

  Properties required for such a binder include bonding between active material particles and fillers, and a composition layer for an electrode containing active material particles (hereinafter also referred to as “active material layer”) and a current collector. Adhesive ability, adhesive ability between a protective film containing a filler and a separator or an active material layer, abrasion resistance in a process of winding an electrode or separator provided with these layers, an active material layer applied by subsequent cutting, etc. There is a powder fall resistance that does not generate fine powder from the protective film. In addition, about the binding ability of the above active material particles and fillers, the binding ability between the active material particles and the current collector, the adhesion ability between the protective film containing the filler and the separator and the active material layer, and the resistance to dusting of these From experience, it is clear that the performance is almost proportional. Therefore, in the present specification, these may be collectively expressed below using the term “adhesion”.

  As an electrode binder, for example, Patent Document 3 and Patent Document 4 disclose a technique for achieving both oxidation resistance and adhesion of an electrode binder by using a rubber polymer and another polymer in combination. Has been proposed. Patent Document 5 discloses a technique for improving adhesion by dissolving polyvinylidene fluoride in a specific organic solvent, applying it onto the current collector surface, and then removing the solvent at a low temperature. Has been proposed.

  As a protective film binder, for example, Patent Document 6 examines a technique for improving battery characteristics by forming a porous layer containing a resin binder containing polyamide, polyimide, and polyamideimide on a porous separator substrate. Has been. Patent Document 7 discusses a technique for improving battery characteristics by forming a porous protective film containing a binder containing a fluorine resin and a rubber resin on at least one surface of a positive electrode and a negative electrode. ing.

JP 2013-30449 A JP 2011-5867 A JP 2011-3529 A JP 2012-151108 A JP 2010-55847 A International Publication No. 2009/041395 JP 2009-54455 A

  However, according to the techniques described in Patent Document 3 and Patent Document 4 in which a rubber-based polymer and another polymer are used in combination, although the adhesion is improved, the oxidation resistance of the organic polymer is greatly impaired. An electricity storage device manufactured using this has a problem that charge and discharge characteristics are irreversibly deteriorated by repeated charge and discharge. Moreover, in the technique described in Patent Document 4, since the acrylic copolymer dispersed in water is used as a binder component, the binder component is not uniform in the coating film depending on the dispersion state of the acrylic copolymer. In some cases, the adhesion is improved but locally insufficient. On the other hand, according to the technique described in Patent Document 5 that uses only a fluorine-containing organic polymer as a binder component, the adhesion is still insufficient.

  On the other hand, according to the materials as described in Patent Document 6 and Patent Document 7, although a short circuit caused by dendrite generated along with charge / discharge can be suppressed by forming a protective film on the separator or electrode surface, Since the permeability and liquid retention of the electrolytic solution are lowered, lithium ions are prevented from adsorbing and desorbing to the active material. As a result, there is a problem that the internal resistance of the electricity storage device increases and the charge / discharge characteristics are deteriorated.

  Thus, in the prior art, a technique for improving the charge / discharge characteristics by improving the adhesion by using an emulsion in which a polymer as a binder component is dispersed in water has been proposed. However, a technique using only a water-soluble polymer as a binder component has not been studied much. If only a water-soluble polymer can be used as the binder component, non-uniformity of the binder component in the coating film is eliminated, and further improvement in adhesion can be expected.

  Accordingly, some embodiments according to the present invention can form a layer having excellent adhesion to a current collector or a separator by solving at least a part of the above-described problem, and also have an electric storage device having excellent charge / discharge characteristics. The slurry for electrical storage devices which can manufacture is provided.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following aspects or application examples.

[Application Example 1]
One aspect of the slurry for an electricity storage device according to the present invention is:
A slurry for an electricity storage device containing 1 to 10 parts by mass of a water-soluble polymer (A) with respect to 100 parts by mass of an active material,
The ratio of the repeating unit derived from (meth) acrylamide contained in 100 parts by mass of the water-soluble polymer (A) is 40 to 100 parts by mass.

[Application Example 2]
One aspect of the slurry for an electricity storage device according to the present invention is:
1-10 mass parts of water-soluble polymers (A) which have a repeating unit derived from (meth) acrylamide are contained with respect to 100 mass parts of fillers.

[Application Example 3]
In the slurry for the electricity storage device of Application Example 2,
The ratio of the repeating unit derived from (meth) acrylamide contained in 100 parts by mass of the water-soluble polymer (A) may be 40 to 100 parts by mass.

[Application Example 4]
In the slurry for electricity storage device of Application Example 2 or Application Example 3,
The filler may be at least one particle selected from the group consisting of silica, titanium oxide, aluminum oxide, zirconium oxide, and magnesium oxide.

[Application Example 5]
In the slurry for an electricity storage device according to any one of Application Examples 1 to 4,
It can contain no water-insoluble polymer.

[Application Example 6]
In the slurry for an electricity storage device of any one of Application Examples 1 to 5,
The water-soluble polymer (A) is a repeating unit derived from at least one selected from the group consisting of an acid having a polymerizable unsaturated double bond, an unsaturated carboxylic acid ester, and an α, β-unsaturated nitrile compound. Can further be included.

[Application Example 7]
In the slurry for an electricity storage device of any one of Application Examples 1 to 6,
The water-soluble polymer (A) may have a weight average molecular weight (Mw) of 300,000 to 6 million.

[Application Example 8]
In the slurry for an electricity storage device of any one of Application Examples 1 to 7,
The water-soluble polymer (A) may have a weight average molecular weight (Mw) / number average molecular weight (Mn) of 3 to 30.

[Application Example 9]
One aspect of the electricity storage device electrode according to the present invention is:
It is characterized by comprising: a current collector; and a layer formed by applying and drying the power storage device slurry of Application Example 1 on the surface of the current collector.

[Application Example 10]
One aspect of the electricity storage device electrode according to the present invention is:
A current collector, and an active material layer formed on the surface of the current collector,
Furthermore, the active material layer is provided with a layer formed by applying and drying the electricity storage device slurry of any one of Application Examples 2 to 4 on the surface of the active material layer.

[Application Example 11]
One aspect of the separator according to the present invention is:
A layer formed by applying and drying the slurry for an electricity storage device according to any one of Application Example 2 to Application Example 4 is provided on the surface.

[Application Example 12]
One aspect of the electricity storage device according to the present invention is:
At least one of the electricity storage device electrode of Application Example 9 or Application Example 10 and the separator of Application Example 11 is provided.

According to the slurry for an electricity storage device according to the present invention, an electricity storage device electrode excellent in binding ability between active material particles and binding ability between the active material particles and the current collector and powder fall resistance, so-called adhesion is manufactured. Can do. Moreover, according to the electrical storage device including the electrical storage device electrode manufactured using the electrical storage device slurry according to the present invention, the discharge rate characteristic which is one of the electrical characteristics is extremely good.

  According to the electricity storage device provided with the protective film produced using the slurry for electricity storage device according to the present invention, it is excellent in electrolyte permeability and liquid retention, and it is possible to suppress an increase in internal resistance. That is, the power storage device according to the present invention has excellent charge / discharge characteristics because the degree of increase in the internal resistance of the power storage device is small even after repeated charge / discharge or overcharge. In addition, the said protective film can also suppress the short circuit resulting from the dendride which generate | occur | produces with charging / discharging by arrange | positioning between a positive electrode and a negative electrode. Since the slurry for an electricity storage device according to the present invention is further excellent in oxidation resistance, it can be particularly suitably used for forming a protective film facing the positive electrode of the electricity storage device.

  Hereinafter, preferred embodiments according to the present invention will be described in detail. It should be understood that the present invention is not limited to only the embodiments described below, and includes various modifications that are implemented without departing from the scope of the present invention. In the present specification, “(meth) acrylic acid” is a concept encompassing both “acrylic acid” and “methacrylic acid”.

1. Power storage device slurry The power storage device slurry according to the present embodiment can be broadly classified into two applications. As the first use, there is an application for producing an electricity storage device electrode. Specifically, it can be used as a slurry for producing an active material layer formed on a current collector surface. As a second application, there is an application for producing a protective film on the surface of an electrode or a separator for suppressing a short circuit caused by dendrid generated along with charge / discharge.

  The water-soluble polymer (A) contained in the electricity storage device slurry according to the present embodiment has not only a function as a thickener typified by conventional carboxymethyl cellulose but also a binding ability and activity between active material particles. It also has a function as a binder for improving the binding ability between the substance particles and the current collector and the resistance to powder falling. Therefore, in the slurry for an electricity storage device according to the present embodiment, it is not necessary to use a water-insoluble polymer (organic particles) having a function as a binder as described in JP2012-151108A. Are better.

  The “water-soluble polymer” in the present invention refers to a polymer having a solubility in 1 g of water at 1 atm and 23 ° C. of 0.01 g or more. The “water-insoluble polymer” in the present invention refers to a polymer having a solubility in 1 g of water at 1 atm and 23 ° C. of less than 0.01 g.

  Hereinafter, the slurry for the electricity storage device used for the application for producing the electricity storage device electrode is referred to as “slurry for the electricity storage device electrode”, and the slurry for the electricity storage device used for the application for producing the protective film is referred to as “the slurry for the protection film” Each slurry will be described in detail.

1.1. Storage Device Electrode Slurry The storage device electrode slurry according to the present embodiment contains 1 to 10 parts by mass of the water-soluble polymer (A) with respect to 100 parts by mass of the active material, and the water-soluble polymer (A) ) The ratio of the repeating unit derived from (meth) acrylamide contained in 100 parts by mass is 40 to 100 parts by mass. Hereafter, each component contained in the slurry for electrical storage device electrodes which concerns on this Embodiment is demonstrated in detail.

1.1.1. Water-soluble polymer (A)
The slurry for an electricity storage device electrode according to the present embodiment includes a water-soluble polymer (A) containing a repeating unit derived from (meth) acrylamide. In addition to the repeating unit derived from (meth) acrylamide, the water-soluble polymer (A) may contain a repeating unit derived from another monomer copolymerizable therewith. Examples of the other monomer include an acid having a polymerizable unsaturated double bond, an unsaturated carboxylic acid ester, an α, β-unsaturated nitrile compound, a conjugated diene compound, and an aromatic vinyl compound.

  Hereinafter, the repeating unit constituting the water-soluble polymer (A), the molecular weight of the water-soluble polymer (A), the physical properties, and the production method will be described in this order.

1.1.1.1. The repeating unit derived from (meth) acrylamide The water-soluble polymer (A) is 40 to 100 parts by mass of the repeating unit derived from (meth) acrylamide contained in 100 parts by mass of the water-soluble polymer (A). It is more preferable that it is 45-95 mass parts, and it is especially preferable that it is 50-85 mass parts. By containing the repeating unit derived from (meth) acrylamide in the above range, the dispersibility of the active material and filler becomes good, and it becomes possible to produce a uniform active material layer and a protective film. Shows excellent charge / discharge characteristics. Furthermore, by containing a repeating unit derived from (meth) acrylamide in the above range, the oxidation resistance of the polymer becomes good, and therefore, deterioration at high voltage is suppressed, and good charge / discharge durability characteristics are exhibited.

（式（１）中、Ｒ^１は水素原子またはメチル基を表す。） (Meth) acrylamide in the present invention is a generic name for compounds having a (meth) acrylamide skeleton represented by the following general formula (1).

(In formula (1), R ¹ represents a hydrogen atom or a methyl group.)

  Examples of such (meth) acrylamide include acrylamide, methacrylamide, N-isopropylacrylamide, N, N-dimethylacrylamide, N, N-dimethylmethacrylamide, N, N-diethylacrylamide, and N, N-diethylmethacrylate. Examples include amide, N, N-dimethylaminopropyl acrylamide, N, N-dimethylaminopropyl methacrylamide, N-methylol methacrylamide, N-methylol acrylamide, diacetone acrylamide, maleic acid amide, and acrylamide t-butyl sulfonic acid. . These (meth) acrylamides may be used alone or in combination of two or more.

1.1.1.2. Repeating unit derived from an acid having a polymerizable unsaturated double bond The water-soluble polymer (A) is an acid having a polymerizable unsaturated double bond (excluding those corresponding to the above (meth) acrylamide). It may have repeating units derived from it. When the water-soluble polymer (A) has a repeating unit derived from an acid having a polymerizable unsaturated double bond, the polymerizable unsaturated double bond contained in 100 parts by mass of the water-soluble polymer (A) The ratio of the repeating unit derived from the acid it has is preferably 0 to 30 parts by mass, and more preferably 5 to 25 parts by mass. When the water-soluble polymer (A) contains a repeating unit derived from an acid having a polymerizable unsaturated double bond within the above range, the stability of the slurry for an electricity storage device electrode according to the present embodiment is improved.

  As the acid having a polymerizable unsaturated double bond, an unsaturated carboxylic acid or an unsaturated sulfonic acid can be preferably used. Specific examples of the acid having a polymerizable unsaturated double bond include, for example, acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, itaconic acid and other unsaturated carboxylic acids; vinyl sulfonic acid, allyl sulfonic acid, An unsaturated sulfonic acid such as methallylsulfonic acid can be mentioned, and one or more selected from these can be used. Among these, at least one selected from the group consisting of acrylic acid, methacrylic acid, itaconic acid, vinyl sulfonic acid, allyl sulfonic acid and methallyl sulfonic acid is preferable.

1.1.1.3. Repeating unit derived from unsaturated carboxylic acid ester The water-soluble polymer (A) may further have a repeating unit derived from an unsaturated carboxylic acid ester. When the water-soluble polymer (A) has a repeating unit derived from an unsaturated carboxylic acid ester, the ratio of the repeating unit derived from the unsaturated carboxylic acid ester contained in 100 parts by mass of the water-soluble polymer (A) is 0-30 parts by mass is preferable, and 1-10 parts by mass is more preferable. By containing the repeating unit derived from the unsaturated carboxylic acid ester in the above range, the obtained water-soluble polymer (A) has a more favorable affinity for the electrolytic solution, and the binder is electrically used in the electricity storage device. While suppressing an increase in internal resistance due to becoming a resistance component, it is possible to prevent a decrease in adhesion due to excessive absorption of the electrolytic solution.

  The unsaturated carboxylic acid ester is preferably a (meth) acrylic acid ester. Specific examples of such (meth) acrylic acid esters include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, i-propyl (meth) acrylate, (meth ) N-butyl acrylate, i-butyl (meth) acrylate, n-amyl (meth) acrylate, i-amyl (meth) acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, (meth ) Monofunctional (meth) acrylate esters such as 2-ethylhexyl acrylate, n-octyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate; glycidyl (meth) acrylate, (meth) Hydroxymethyl acrylate, hydroxyethyl (meth) acrylate, ethylene glycol (meth) acrylate, di (meth) Ethylene glycol acrylate, propylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, allyl (meth) acrylate, Polyfunctional (meth) acrylic acid esters such as ethylene di (meth) acrylate; compounds represented by the following general formula (1), (meth) acrylic acid 3 [4 [1-trifluoromethyl-2,2-bis Fluorine-containing (meth) acrylic acid esters such as [bis (trifluoromethyl) fluoromethyl] ethynyloxy] benzooxy] 2-hydroxypropyl can be mentioned, and can be one or more selected from these. .

（式（２）中、Ｒ^２は水素原子またはメチル基であり、Ｒ^３はフッ素原子を含有する炭素数１〜１８の炭化水素基である。）

(In the formula (2), ^{R 2} is a hydrogen atom or a methyl group, ^{R 3} is a hydrocarbon group having 1 to 18 carbon atoms containing a fluorine atom.)

  In addition, the “polyfunctional (meth) acrylic acid ester” in the present invention means other polymerizable double bond, epoxy group, in addition to one polymerizable double bond possessed by (meth) acrylic acid ester, It means having at least one functional group selected from the group consisting of hydroxy groups.

  Among the monofunctional (meth) acrylates exemplified above, methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, (meth) acrylic It is preferably at least one selected from the group consisting of hydroxymethyl acid and hydroxyethyl (meth) acrylate, and particularly preferably methyl (meth) acrylate.

  Among the polyfunctional (meth) acrylic esters exemplified above, it is preferably at least one selected from the group consisting of glycidyl (meth) acrylate and hydroxyethyl (meth) acrylate, and glycidyl (meth) acrylate It is particularly preferred that

1.1.1.4. Repeating unit derived from α, β-unsaturated nitrile compound The water-soluble polymer (A) may further have a repeating unit derived from the α, β-unsaturated nitrile compound. When the polymer (A) has a repeating unit derived from an α, β-unsaturated nitrile compound, the repeating derived from the α, β-unsaturated nitrile compound contained in 100 parts by mass of the water-soluble polymer (A) The ratio of the unit is preferably 0 to 30 parts by mass, and more preferably 1 to 10 parts by mass. By containing the repeating unit derived from the α, β-unsaturated nitrile compound in the above range, the affinity of the water-soluble polymer (A) for the electrolytic solution is improved, so that the electrolytic solution absorption ability is improved. That is, the presence of the nitrile group makes it easy for the solvent to uniformly diffuse into the network structure formed of polymer chains formed in the electrode, so that the solvated lithium ions can easily move through the network structure. Thereby, it is thought that the diffusibility of lithium ion improves, As a result, electrode resistance falls and it is thought that a more favorable charge / discharge characteristic can be implement | achieved.

  Specific examples of the α, β-unsaturated nitrile compound include acrylonitrile, methacrylonitrile, α-chloroacrylonitrile, α-ethylacrylonitrile, vinylidene cyanide and the like. Can be. Among these, at least one selected from acrylonitrile and methacrylonitrile is preferable, and acrylonitrile is particularly preferable.

1.1.1.5. Repeating unit derived from other monomer The water-soluble polymer (A) may further contain a repeating unit derived from a conjugated diene compound or an aromatic vinyl compound.

  Examples of the conjugated diene compound include 1,3-butadiene, 2-methyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 2-chloro-1,3-butadiene and the like. , One or more selected from these.

  Specific examples of the aromatic vinyl compound include styrene, α-methylstyrene, p-methylstyrene, vinyltoluene, chlorostyrene, divinylbenzene, and the like, and one or more selected from these can be used. be able to.

In addition, since the water-soluble polymer (A) has a low oxidation potential when used in an environment exposed to a high voltage, the repeating unit derived from the conjugated diene compound and the repeating unit derived from the aromatic vinyl compound are substantially included. It is preferably not included. Examples of the environment exposed to high voltage include positive electrodes such as lithium ion batteries, lithium ion capacitors, and electric double layer capacitors, and protective films formed between the positive electrode surface and the separator.

1.1.1.6. Characteristics of water-soluble polymer (A) 1.1.1.1.6.1. Molecular weight of water-soluble polymer (A) The weight average molecular weight (Mw) of the water-soluble polymer (A) is preferably in the range of 300,000 to 6 million, more preferably 550,000 to 4.5 million. , 600,000 to 3,000,000 is particularly preferable. The reason why the charge / discharge characteristics are manifested when the slurry for an electricity storage device electrode according to the present embodiment contains the water-soluble polymer (A) having the above-described molecular weight range is not necessarily clear. However, it is estimated as follows.

  That is, when the molecular weight of the polymer is less than 300,000, there is a high possibility that the polymer will elute into the electrolyte solution. In this case, not only the adhesiveness is lowered, but also there is a risk that the low molecular weight polymer component eluted in the electrolytic solution is adversely affected on the charge / discharge characteristics such as being electrolyzed during the charge / discharge. On the other hand, when the molecular weight exceeds 6 million, there is a risk that the binder does not swell sufficiently depending on the electrolyte. The water-soluble polymer (A) according to the present embodiment is considered to have further improved charge / discharge characteristics by having a sufficiently large molecular weight as described above.

  The weight average molecular weight (Mw) / number average molecular weight (Mn) of the water-soluble polymer (A), the so-called dispersion ratio, is preferably 3-30, preferably 7-30, and 10-30. It is more preferable. Generally, the value of the dispersion ratio is considered to mean the spread of the molecular weight distribution, and the closer this value is to 1, the narrower the molecular weight distribution is. The reason why the charge / discharge characteristics are manifested when the slurry for the electricity storage device electrode according to the present embodiment contains the water-soluble polymer (A) having a specific spread in the above range is not necessarily clear. However, it is estimated as follows.

  In general, in the case of a polymer having a narrow molecular weight distribution, i.e., a uniform molecular weight, the strength is increased when the molecular weight is large, but it tends to be brittle, and the polymer tends to be flexible when the molecular weight is small. There is a trade-off relationship that the strength decreases. On the contrary, when the molecular weight distribution is wide, that is, when a wide range from high molecular weight to low molecular weight is mixed, the ultra-high molecular weight polymer is excessively contained, so that the viscosity and thixotropy become extremely large when made into a solution. Tend. When this is applied to the application of the present invention, a slurry having good dispersibility and fluidity can be prepared by using a polymer having a specific molecular weight distribution. An electrode or a protective film formed from a slurry having good dispersibility and fluidity has characteristics that it is uniform and has few structural defects. In addition, by having a specific molecular weight distribution, it is possible to form a high-strength electrode while maintaining flexibility, so that the uniformity of the structure is unlikely to be lost and the initial good characteristics can be maintained, and the durability is excellent. This is considered to be an electrode and a protective film.

  In addition, the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the water-soluble polymer (A) can be obtained, for example, by converting a measured value by a GPC (gel permeation chromatography) method into standard polyethylene oxide. it can.

1.1.1.1.2. Degree of neutralization of water-soluble polymer (A) When the water-soluble polymer (A) has an acid group, the degree of neutralization can be appropriately adjusted according to the use. The degree of neutralization when the active material or filler is dispersed is not particularly limited, but is preferably 0.7 to 1.0 and preferably 0.85 to 1.0 after the formation of the electrode or the protective film. Is more preferable. By setting the degree of neutralization after electrode preparation within the above range, most of the acid is in a neutralized state, and it is preferable to combine with Li ions or the like in the battery without causing a decrease in capacity. Examples of the neutralized salt include Li salt, Na salt, K salt, ammonium salt, Mg salt, Ca salt, Zn salt, Al salt and the like.

1.1.1.7. Production Method of Water-Soluble Polymer (A) The method for synthesizing the water-soluble polymer (A) is not particularly limited, but polymerization performed in a solvent containing water as a main component is preferable. A particularly preferred polymerization form is aqueous solution polymerization. The polymerization initiator used in the synthesis of the water-soluble polymer (A) is preferably a water-soluble radical initiator, and is a persulfate such as lithium persulfate, potassium persulfate, sodium persulfate, ammonium persulfate or 4,4′-azobis. Water-soluble azo initiators such as (4-cyanovaleric acid) are particularly preferred. From the viewpoint of obtaining a water-soluble polymer (A) having the above-mentioned weight average molecular weight (300,000 to 6,000,000), the amount of the polymerization initiator used is 0 with respect to 100 parts by mass of the total mass of monomers to be polymerized. It is preferable that it is 0.1-1.0 mass part.

  The polymerization temperature during the synthesis of the water-soluble polymer (A) is not particularly limited, but the synthesis is carried out in the range of 30 to 95 ° C. in consideration of the production time and the conversion rate (reaction rate) of the monomer to the copolymer. It is preferable to carry out, and 50-85 degreeC is especially preferable. However, in order to obtain a water-soluble polymer (A) having a target molecular weight or molecular weight distribution, it is necessary to control the set temperature during polymerization once within ± 3 ° C. Further, at the time of polymerization, it is possible to use a pH adjusting agent, EDTA which is a metal ion sealing agent or a salt thereof for the purpose of improving production stability.

  In addition, pH may be adjusted with a general neutralizing agent such as ammonia, organic amine, potassium hydroxide, sodium hydroxide, lithium hydroxide before the polymerization or when water-solubilizing the polymer. It is preferable to adjust the pH to the range of 5-11. It is also possible to use EDTA which is a metal ion sealing agent or a salt thereof.

  In particular, in order to control the molecular weight and molecular weight distribution of the water-soluble polymer (A), the type and amount of the initiator, the temperature control during the polymerization, the time until the total amount of monomer is added, after the total amount of monomer is added Temperature management and temperature holding time are important. For example, the polymer described in JP2012-151108A uses about 2 parts by mass of an initiator (ammonium persulfate) with respect to 100 parts by mass of the monomer. Generally, when the amount of the initiator increases with respect to the amount of the monomer, the molecular weight decreases, but it is considered that the above-described weight average molecular weight cannot be reached by such a synthesis method. In addition, since the water-soluble polymer (A) is obtained by radical polymerization in a solvent containing water as a main component, temperature control and reaction time are strictly controlled in order to synthesize a polymer having a desired molecular weight. There is a need to. Such time and temperature management needs to be adjusted in a timely manner according to the type of monomer used. For example, when controlling the molecular weight and molecular weight distribution of a water-soluble polymer (A) containing 40 to 100 parts by mass of repeating units derived from (meth) acrylamide with respect to 100 parts by mass of all repeating units, temperature control during polymerization It is necessary to carry out at about ± 3 ° C. with respect to the set temperature, and the time until addition of the whole amount of monomer needs to be carried out within about ± 5 minutes with respect to the set time. The control must be performed at about ± 3 ° C., and must be strictly controlled to the temperature holding time after addition of the entire amount of monomer.

1.1.2. Active material There is no restriction | limiting in particular as a material which comprises the active material contained in the slurry for electrical storage device electrodes which concerns on this Embodiment, According to the kind of target electrical storage device, a suitable material can be selected suitably. Examples of the active material include carbon materials, silicon materials, oxides containing lithium atoms, lead compounds, tin compounds, arsenic compounds, antimony compounds, aluminum compounds, and the like.

  Examples of the carbon material include amorphous carbon, graphite, natural graphite, mesocarbon microbeads (MCMB), and pitch-based carbon fibers.

Examples of the silicon material include silicon simple substance, silicon oxide, and silicon alloy. For example, SiC, SiO _x C _y (0 <x ≦ 3, 0 <y ≦ 5), Si ₃ N ₄ , Si oxide complex represented by Si ₂ N ₂ O, SiO _x (0 <x ≦ 2) (for example, materials described in JP-A Nos. 2004-185810 and 2005-259697), A silicon material described in JP-A No. 2004-185810 can be used. The silicon oxide is preferably a silicon oxide represented by the composition formula SiO _x (0 <x <2, preferably 0.1 ≦ x ≦ 1). The silicon alloy is preferably an alloy of silicon and at least one transition metal selected from the group consisting of titanium, zirconium, nickel, copper, iron and molybdenum. These transition metal silicon alloys are preferably used because they have high electronic conductivity and high strength. Moreover, since the transition metal existing on the surface of the active material is oxidized and becomes an oxide having a hydroxyl group on the surface when the active material contains these transition metals, the binding force with the binder is also improved. preferable. As the silicon alloy, it is more preferable to use a silicon-nickel alloy or a silicon-titanium alloy, and it is particularly preferable to use a silicon-titanium alloy. The silicon content in the silicon alloy is preferably 10 mol% or more, and more preferably 20 to 70 mol%, based on all the metal elements in the alloy. Note that the silicon material may be single crystal, polycrystalline, or amorphous.

Moreover, when using a silicon material as an active material, you may use together active materials other than a silicon material. Examples of such active materials include the above carbon materials; conductive polymers such as polyacene; A _X B _Y O _Z (where A is an alkali metal or transition metal, B is cobalt, nickel, aluminum, tin, manganese) At least one selected from transition metals such as O represents an oxygen atom, and X, Y and Z are 1.10>X> 0.05, 4.00>Y> 0.85, 5.00>, respectively. Z> 1.5 is a number in the range.) And other metal oxides. Among these, it is preferable to use a carbon material in combination because the volume change associated with insertion and extraction of lithium is small.

Examples of the oxide containing a lithium atom include lithium cobaltate, lithium nickelate, lithium manganate, ternary nickel cobalt lithium manganate, LiFePO ₄ , LiCoPO ₄ , LiMnPO ₄ , Li _0.90 Ti _0.05 Nb. _0.05 Fe _0.30 Co _0.30 Mn _0.30 PO _{4 and the} like.

  The shape of the active material is preferably granular. The average particle size of the active material is preferably 0.1 to 100 μm, and more preferably 0.5 to 20 μm.

  The use ratio of the active material needs to be used in such a ratio that the content of the water-soluble polymer (A) is 1 to 10 parts by mass with respect to 100 parts by mass of the active material. It is preferable to use in such a ratio that it becomes, and it is more preferable to use it in a ratio that becomes 1 to 3 parts by mass. By setting it as such a content rate, it is excellent in adhesiveness, and also the electrode with small electrode resistance and the charge / discharge characteristic can be manufactured. When the content of the water-soluble polymer (A) is less than the above range, the function as a binder becomes insufficient, so that the active material layer is likely to crack, and the electrode is not excellent in charge / discharge durability characteristics. . On the other hand, when the content ratio of the water-soluble polymer (A) exceeds the above range, the leveling property is insufficient when applying the slurry, so that the uniformity of the thickness of the coating film may be impaired. When an electrode having a non-uniform thickness is used, an in-plane distribution of charge / discharge reaction occurs, making it difficult to achieve stable battery performance.

1.1.3. Liquid medium The slurry for an electricity storage device electrode according to the present embodiment contains a liquid medium. The liquid medium is preferably an aqueous medium containing water. The aqueous medium can contain a non-aqueous medium having a standard boiling point of 80 to 350 ° C. from the viewpoint of improving the coating property. Specific examples of such a non-aqueous medium include, for example, amide compounds such as N-methylpyrrolidone, dimethylformamide, and N, N-dimethylacetamide; hydrocarbons such as toluene, xylene, n-dodecane, and tetralin; 2-ethyl Alcohols such as -1-hexanol, 1-nonanol, and lauryl alcohol; ketones such as methyl ethyl ketone, cyclohexanone, phorone, acetophenone, and isophorone; esters such as benzyl acetate, isopentyl butyrate, methyl lactate, ethyl lactate, and butyl lactate; o-toluidine, Examples include amine compounds such as m-toluidine and p-toluidine; lactones such as γ-butyrolactone and δ-butyrolactone; sulfoxide and sulfone compounds such as dimethyl sulfoxide and sulfolane, and the like. One or more selected from the above can be used. Among these, it is preferable to use N-methylpyrrolidone from the viewpoint of workability when applying the slurry for the electricity storage device electrode. When the liquid medium is an aqueous medium, 90% by mass or more is preferably water and more preferably 98% by mass or more is water in the total amount of 100% by mass of the liquid medium. The slurry for an electricity storage device according to the present embodiment uses an aqueous medium as a liquid medium, thereby reducing the degree of adverse effects on the environment and increasing the safety for handling workers.

  The content ratio of the non-aqueous medium contained in the aqueous medium is preferably 10% by mass or less, more preferably 5% by mass or less, particularly not substantially contained in 100% by mass of the aqueous medium. preferable. Here, “substantially does not contain” means that a non-aqueous medium is not intentionally added as a liquid medium, and is inevitably mixed when preparing a slurry for an electricity storage device electrode. May be included.

1.1.4. Other Additives A conductive additive, a thickener, a pH adjuster, a corrosion inhibitor, and the like can be added to the electricity storage device electrode slurry according to the present embodiment as necessary.

1.1.4.1. Conductive aids Specific examples of conductive aids include carbon in lithium ion secondary batteries; in nickel metal hydride secondary batteries, cobalt oxide at the positive electrode: nickel powder, cobalt oxide, titanium oxide, carbon at the negative electrode, etc. Are used respectively. In both the batteries, examples of carbon include graphite, activated carbon, acetylene black, furnace black, graphite, carbon fiber, and fullerene. Among these, acetylene black or furnace black can be preferably used. The use ratio of the conductive assistant is preferably 20 parts by mass or less, more preferably 1 to 15 parts by mass, and particularly preferably 2 to 10 parts by mass with respect to 100 parts by mass of the active material.

1.1.4.2. Thickener The slurry for an electricity storage device electrode according to the present embodiment can contain a thickener from the viewpoint of adjusting its fluidity and stability. Examples of such thickeners include cellulose compounds such as carboxymethyl cellulose, methyl cellulose, and hydroxypropyl cellulose; ammonium salts or alkali metal salts of the above cellulose compounds; poly (meth) acrylic acid, modified poly (meth) acrylic acid, and the like. Polycarboxylic acids of the above; alkali metal salts of the above polycarboxylic acids; polyvinyl alcohol (co) polymers such as polyvinyl alcohol, modified polyvinyl alcohol, ethylene-vinyl alcohol copolymers; (meth) acrylic acid, maleic acid and fumaric acid And water-soluble polymers such as saponified products of copolymers of unsaturated carboxylic acids and vinyl esters. Among these, particularly preferred thickeners include alkali metal salts of carboxymethyl cellulose and alkali metal salts of poly (meth) acrylic acid.

  In addition, when using in the environment exposed to a high voltage, it is preferable not to contain carboxymethylcellulose and its salt since oxidation potential is low. By adding carboxymethyl cellulose and its salt, the flexibility of the electrode may be reduced, and the winding property may be impaired, or the adhesion of the active material layer may be insufficient. Examples of the environment exposed to high voltage include positive electrodes such as lithium ion batteries, lithium ion capacitors, and electric double layer capacitors, and protective films formed between the positive electrode surface and the separator.

  When the electricity storage device electrode slurry according to the present embodiment contains a thickener, the use ratio of the thickener is preferably 20% by mass or less with respect to the total solid content of the electricity storage device electrode slurry. More preferably, it is 0.1-15 mass%, Most preferably, it is 0.5-10 mass%.

1.1.4.3. pH adjusting agent, corrosion inhibitor The slurry for an electricity storage device electrode according to the present embodiment contains a pH adjusting agent or a corrosion inhibitor for the purpose of suppressing the corrosion of the current collector applied according to the type of the active material. Can be contained.

  Examples of the pH adjuster include hydrochloric acid, phosphoric acid, sulfuric acid, acetic acid, formic acid, ammonium phosphate, ammonium sulfate, ammonium acetate, ammonium formate, and ammonium chloride, and sulfuric acid and ammonium sulfate are preferable.

  Corrosion inhibitors include ammonium metavanadate, sodium metavanadate, potassium metavanadate, ammonium metatungstate, sodium metatungstate, potassium metatungstate, ammonium paratungstate, sodium paratungstate, potassium paratungstate, and molybdic acid. Ammonium, sodium molybdate, potassium molybdate and the like can be mentioned, and ammonium paratungstate, ammonium metavanadate, sodium metavanadate, potassium metavanadate and ammonium molybdate are preferable.

1.1.5. Method for producing power storage device electrode slurry The power storage device electrode slurry according to the present embodiment includes a water-soluble polymer (A) (or an aqueous solution containing the water-soluble polymer (A)), an active material, water, It can manufacture by mixing the additive used as needed. These mixing can be performed by stirring by a known method, and for example, a stirrer, a defoamer, a bead mill, a high-pressure homogenizer, or the like can be used.

  As the mixing and stirring for producing the slurry for the electricity storage device electrode according to the present embodiment, a mixer capable of stirring to such an extent that no agglomerates of the active material remain in the slurry, and a sufficient dispersion condition as necessary. Must be selected. The degree of dispersion can be measured by a particle gauge, but it is preferable to mix and disperse so that aggregates larger than at least 100 μm are eliminated. Examples of the mixer that meets such conditions include a ball mill, a sand mill, a pigment disperser, a crusher, an ultrasonic disperser, a homogenizer, a planetary mixer, and a Hobart mixer.

1.2. Protective film slurry Protective film slurry is a dispersion used to form a protective film on the surface of an electrode or separator or both by applying it to the surface of the electrode or separator or both. I mean. The slurry for a protective film according to the present embodiment contains 1 to 10 parts by mass of the water-soluble polymer (A) having a repeating unit derived from (meth) acrylamide with respect to 100 parts by mass of the filler. To do. The protective film slurry according to the present embodiment is mainly different in that a filler is added instead of the active material in the above-described slurry for an electricity storage device electrode. Therefore, a difference from the above-described slurry for an electricity storage device electrode will be described below.

1.2.1. Filler The slurry for a protective film according to the present embodiment can improve the toughness of the formed protective film by containing a filler. As the filler, silica, titanium oxide (titania), aluminum oxide (alumina), zirconium oxide (zirconia), magnesium oxide (magnesia), or the like can be used. Among these, titanium oxide and aluminum oxide are preferable from the viewpoint of further improving the toughness of the protective film. Further, as the titanium oxide, rutile type titanium oxide is more preferable.

  The average particle size of the filler is preferably 1 μm or less, and more preferably in the range of 0.1 to 0.8 μm. In addition, it is preferable that the average particle diameter of a filler is larger than the average hole diameter of the separator which is a porous film. Thereby, the damage to a separator can be reduced and a filler can be prevented from being clogged with the micropore of a separator.

  The slurry for protective film which concerns on this Embodiment needs to contain 1-10 mass parts of water-soluble polymers (A) with respect to 100 mass parts of fillers. When the content ratio of the water-soluble polymer (A) is 1 to 10 parts by mass, the balance between the toughness of the protective film to be formed and the lithium ion permeability is improved, and as a result, the resistance of the obtained electricity storage device The rate of increase can be made lower.

1.2.2. Other Additives The slurry for the protective film according to the present embodiment may contain the materials and addition amounts described in the above-mentioned slurry “1.1.4. Other Additives” for the electricity storage device electrode as necessary. It can be used as needed.

1.2.3. Method for Producing Slurry for Protective Film A slurry for protective film according to the present embodiment is used as necessary, with a water-soluble polymer (A) (or an aqueous solution containing a water-soluble polymer (A)), a filler, and the like. It is prepared by mixing the additive. As a means for mixing them, for example, a known mixing device such as a ball mill, a sand mill, a pigment disperser, a crusher, an ultrasonic disperser, a homogenizer, a planetary mixer, a Hobart mixer can be used.

  For mixing and stirring for producing the protective film slurry according to the present embodiment, it is necessary to select a mixer that can stir to such an extent that filler aggregates do not remain in the slurry and, if necessary, sufficient dispersion conditions. There is. The degree of dispersion can be measured by a particle gauge, but it is preferable to mix and disperse so that aggregates larger than at least 100 μm are eliminated. Examples of the mixer that meets such conditions include a ball mill, a sand mill, a pigment disperser, a crusher, an ultrasonic disperser, a homogenizer, a planetary mixer, and a Hobart mixer.

1.3. Slurry characteristics The slurry for an electricity storage device according to the present embodiment preferably has a spinnability of 30 to 80%, more preferably 33 to 79%, and particularly preferably 35 to 78%. . When the spinnability is less than the above range, the leveling property is insufficient when applying the slurry, and thus the uniformity of the thickness of the coating film may be impaired. If an electrode or a protective film having a non-uniform thickness is used, an in-plane distribution of charge / discharge reaction occurs, making it difficult to achieve stable battery performance. On the other hand, if the spinnability exceeds the above range, dripping easily occurs when applying the slurry,
It is difficult to obtain stable quality electrodes and protective films. Therefore, if the spinnability is within the above range, the occurrence of these problems can be suppressed, and it becomes easy to manufacture an electricity storage device having both good electrical characteristics and adhesion.

The “threadability” in the present specification is a physical property measured as follows. First, a Zaan cup (made by Dazai Equipment Co., Ltd., Zaan Bisco City Cup No. 5) having an opening with a diameter of 5.2 mm at the bottom is prepared. With this opening closed, 40 g of slurry is poured into the Zahn cup. Thereafter, when the opening is opened, the slurry flows out from the opening. Here, it is possible to obtain T ₀ when opening the _opening, the T _A when the slurry of the thread is _finished, when the outflow of the slurry is completed when the T _B, the following equation (3) .
Spinnability (%) = ((T _A −T ₀ ) / (T _B −T ₀ )) × 100 (3)

2. The electricity storage device electrode according to the present embodiment includes a current collector and a layer formed by applying and drying the above-mentioned slurry for an electricity storage device electrode on the surface of the current collector. is there. Such an electricity storage device electrode is formed by applying the aforementioned slurry for an electricity storage device electrode on the surface of an appropriate current collector such as a metal foil to form a coating film, and then drying the coating film to form an active material layer. Can be manufactured. In the electricity storage device electrode thus manufactured, an active material layer containing the water-soluble polymer (A), the active material, and an optional component added as necessary is bound on the current collector. It will be. Such an electricity storage device electrode has excellent adhesion between the current collector and the active material layer, and therefore has good charge / discharge rate characteristics, which is one of the electrical characteristics.

  The current collector is not particularly limited as long as it is made of a conductive material. In a lithium ion secondary battery, a current collector made of metal such as iron, copper, aluminum, nickel, and stainless steel is used. In particular, when aluminum is used for the positive electrode and copper is used for the negative electrode, the above-mentioned storage device electrode The effect of the slurry is most apparent. As the current collector in the nickel metal hydride secondary battery, a punching metal, an expanded metal, a wire mesh, a foam metal, a mesh metal fiber sintered body, a metal plated resin plate, or the like is used. The shape and thickness of the current collector are not particularly limited, but it is preferable that the current collector has a sheet shape with a thickness of about 0.001 to 0.5 mm.

  There is no particular limitation on the method for applying the slurry for the electricity storage device electrode to the current collector. The coating can be performed by an appropriate method such as a doctor blade method, a dip method, a reverse roll method, a direct roll method, a gravure method, an extrusion method, a dipping method, or a brush coating method. The coating amount of the power storage device electrode slurry is not particularly limited, but the thickness of the active material layer formed after removing the liquid medium (which is a concept including both water and a non-aqueous medium that is optionally used). However, it is preferable to set it as the quantity used as 0.005-5 mm, and it is more preferable to set it as the quantity used as 0.01-2 mm. When the thickness of the active material layer is within the above range, the active material layer can be effectively infiltrated with the electrolytic solution. As a result, it is preferable because the metal ions can be easily transferred between the active material and the electrolytic solution in the active material layer, so that the electrode resistance can be further reduced. In addition, since the thickness of the active material layer is within the above range, even when the electrode is folded or wound, the active material layer is not peeled off from the current collector. It is preferable at the point from which the electrical storage device electrode which is favorable and is rich in flexibility is obtained.

  There is no particular limitation on the drying method from the coated film after coating (method for removing water and optionally used non-aqueous medium); for example, drying with warm air, hot air, low humidity air; vacuum drying; (far) infrared , Drying by irradiation with an electron beam or the like. The drying speed is appropriately set so that the liquid medium can be removed as quickly as possible within a speed range in which the active material layer does not crack due to stress concentration or the active material layer does not peel from the current collector. be able to.

  Furthermore, it is preferable to increase the density of the active material layer by pressing the dried current collector and to adjust the porosity to the range shown below. Examples of the pressing method include a die press and a roll press. The press conditions should be set appropriately depending on the type of press equipment used and the desired values of the porosity and density of the active material layer. This condition can be easily set by a few preliminary experiments by those skilled in the art. For example, in the case of a roll press, the linear pressure of the roll press machine is 0.1 to 10 (t / cm), preferably 0. At a pressure of 5 to 5 (t / cm), for example, at a roll temperature of 20 to 100 ° C., the current collector feed speed (roll rotation speed) after drying is 1 to 80 m / min, preferably 5 to 50 m / min. It can be performed in min.

The density of the active material layer after pressing, preferably in the 1.5~5.0g / cm ^3, more preferably to 1.5~4.0g / cm ^3, 1.6~3.8g / Cm ³ is particularly preferable.

3. Protective film A protective film can be formed by applying the above-mentioned slurry for protective film on the surface of the positive electrode, negative electrode or separator and drying it. Specific embodiments of the protective film include the following three embodiments.

(1) As a 1st aspect, a protective film can be formed in the active material layer surface by apply | coating and drying the above-mentioned slurry for protective films on the active material layer surface of a positive electrode and / or a negative electrode.
(2) As a 2nd aspect, a protective film can be formed in the surface of a separator by apply | coating and drying the above-mentioned slurry for protective films directly on the separator surface.
(3) As a third aspect, when a functional layer is formed on the separator surface, the protective film is applied to the surface of the functional layer by applying the above-mentioned slurry for protective film on the surface of the functional layer and drying it. Can be formed.

  There is no particular limitation on the method of applying the protective film slurry to the positive electrode, negative electrode or separator. The coating can be performed by an appropriate method such as a doctor blade method, a dip method, a reverse roll method, a direct roll method, a gravure method, an extrusion method, a dipping method, or a brush coating method. The coating amount of the protective film slurry is not particularly limited, but the thickness of the protective film formed after removing the liquid medium is preferably 0.5 to 4 μm, and preferably 0.5 to 3 μm. It is more preferable to use the amount. When the thickness of the protective film is in the above range, the permeability of the electrolytic solution into the electrode and the liquid retaining property are improved, and an increase in the internal resistance of the electrode can be suppressed.

  There is no particular limitation on the drying method from the coated film after coating (method for removing water and optionally used non-aqueous medium); for example, drying with warm air, hot air, low humidity air; vacuum drying; (far) infrared , Drying by irradiation with an electron beam or the like. The drying speed is appropriately set so that the liquid medium can be removed as quickly as possible within a speed range in which the active material layer does not crack due to stress concentration or the active material layer does not peel from the current collector. be able to. Specifically, the coating film is preferably dried at a temperature of 20 to 250 ° C., more preferably 50 to 150 ° C., preferably for 1 to 120 minutes, more preferably 5 to 60 minutes. be able to.

4). Power Storage Device The power storage device according to the present embodiment only needs to include at least one of the above-described power storage device electrode and the separator including the above-described protective film. As a specific method for manufacturing an electricity storage device, a positive electrode and a negative electrode are laminated with a separator for preventing a short circuit between the electrodes, or a positive electrode, a separator, a negative electrode, and a separator are laminated in this order to form an electrode. / Separator laminated body, this may be wound or folded according to the shape of the battery, put into a battery container, and an electrolyte solution is injected into the battery container and sealed. In addition, the shape of the battery can be an appropriate shape such as a coin shape, a button shape, a sheet shape, a cylindrical shape, a square shape, a flat shape, or the like.

  The electrolyte solution may be liquid or gel, and an electrolyte that effectively expresses the function as a battery may be selected from the known electrolytes used for the electricity storage device according to the type of the active material. The electrolytic solution can be a solution in which an electrolyte is dissolved in a suitable solvent.

As the electrolyte, in the lithium ion secondary battery, any conventionally known lithium salt can be used, and specific examples thereof include, for example, LiClO ₄ , LiBF ₄ , LiPF ₆ , LiCF ₃ CO ₂ , LiAsF. ₆ , LiSbF ₆ , LiB ₁₀ Cl ₁₀ , LiAlCl ₄ , LiCl, LiBr, LiB (C ₂ H ₅ ) ₄ , LiCF ₃ SO ₃ , LiCH ₃ SO ₃ , LiC ₄ F ₉ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, lithium of lower fatty acid carboxylate etc. can be illustrated. In a nickel metal hydride secondary battery, for example, an aqueous potassium hydroxide solution having a conventionally known concentration of 5 mol / liter or more can be used.

  The solvent for dissolving the electrolyte is not particularly limited. Specific examples thereof include carbonate compounds such as propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, methyl ethyl carbonate, and diethyl carbonate; Lactone compounds such as butyrolactone; ether compounds such as trimethoxymethane, 1,2-dimethoxyethane, diethyl ether, 2-ethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran; sulfoxide compounds such as dimethyl sulfoxide, etc. One or more selected from among them can be used. The concentration of the electrolyte in the electrolytic solution is preferably 0.5 to 3.0 mol / L, more preferably 0.7 to 2.0 mol / L.

  The power storage device according to the present embodiment is suitable as a secondary battery or a capacitor mounted on an automobile such as an electric vehicle, a hybrid car, and a truck, and also used as a secondary battery used in AV equipment, OA equipment, communication equipment, and the like. It is also suitable as a battery or a capacitor.

5. EXAMPLES Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited to these examples. “Part” and “%” in Examples and Comparative Examples are based on mass unless otherwise specified.

5.1. Example 1
5.1.1. Synthesis and Evaluation of Water-Soluble Polymer (A) (1) Preparation of Aqueous Solution Containing Water-Soluble Polymer (A) The interior of a 7-L separable flask was sufficiently purged with nitrogen, and charged with 1050 parts by weight of water. The temperature was raised to 70 ° C., and then 0.3 part by mass of sodium persulfate was added. Next, a mixed solution of 110 parts by mass of water, 80 parts by mass of acrylamide, 10 parts by mass of acrylic acid, and 10 parts by mass of ethyl acrylate was added dropwise over 1 hour, reacted at 70 ° C. ± 3 ° C. for 2 hours, and further 90 ° C. The reaction was performed at ± 3 ° C. for 2 hours. Then, it cooled and adjusted to pH 7 with 20 wt% sodium hydroxide aqueous solution, and obtained the aqueous solution containing 8 wt% of water-soluble polymers (A). An aqueous solution containing 8 wt% of the water-soluble polymer (A) thus obtained was designated as a binder composition S1 for an electricity storage device. It was 3000 mPa * s when this binder composition S1 for electrical storage devices was adjusted to 25 degreeC, and the viscosity was measured using the BM type | mold viscosity meter.

(2) Measurement of molecular weight The weight average molecular weight (Mw) of the water-soluble polymer (A) measured under the following conditions is 6 × 10 ⁶ , and the value of weight average molecular weight (Mw) / number average molecular weight (Mn) ( The dispersion ratio) was 30.
・ Measurement equipment: GPC (model number: HLC-8220) manufactured by Tosoh Corporation
Column: TSKgel guardcolumn PW _XL (manufactured by Tosoh Corporation), TSK-GEL G2500PW _XL (manufactured by Tosoh Corporation), TSK-GEL GMPW _XL (manufactured by Tosoh Corporation)
Eluent: 0.1M NaNO ₃ aqueous solution Calibration curve: standard polyethylene oxide Measurement method: Dissolved in the eluent so that the concentration of the water-soluble polymer (A) is 0.3 wt%, and measured after filter filtration.

5.1.2. Preparation and Evaluation of Positive Electrode Slurry and Negative Electrode Slurry (1) Preparation of Positive Electrode Slurry A power storage device obtained above in a biaxial planetary mixer (trade name “TK Hibismix 2P-03” manufactured by PRIMIX Corporation) The binder composition S1 was added in an amount corresponding to 1.5 parts by mass in terms of the water-soluble polymer (A), and a commercially available nickel / manganese / cobalt acid lithium (nickel (D50 value) of 10 μm) Ni), cobalt (Co), manganese (Mn) ratio 1: 1: 1) 100 parts by mass of active material particles, 2 parts by mass of acetylene black, 0.5 parts by mass of sodium vanadate and 4 parts by mass of water were added, Stirring was performed at 90 rpm for 1 hour. After adding water to the obtained paste to adjust the solid content concentration to 70%, using a stirring defoaming machine (trade name “Awatori Nentaro” manufactured by Shinky Co., Ltd.) for 2 minutes at 200 rpm. The slurry for positive electrode was prepared by stirring and mixing at 800 rpm for 5 minutes and further under vacuum (about 5.0 × 10 ³ Pa) at 1,800 rpm for 1.5 minutes.

(2) Preparation of slurry for negative electrode A water-soluble polymer was prepared by using the biaxial planetary mixer (trade name “TK Hibismix 2P-03” manufactured by PRIMIX Corporation) and the binder composition S1 for an electricity storage device obtained above. (A) An amount corresponding to 1 part by mass is introduced, 100 parts by mass of graphite (in terms of solid content), 4 parts by mass of acetylene black, and 53 parts by mass of ion-exchanged water are introduced as the negative electrode active material. Stir for hours. After adding 40 parts by mass of water, using a stirring defoamer (product name “Awatori Nertaro” manufactured by Sinky Co., Ltd.) for 2 minutes at 200 rpm, then 5 minutes at 1,800 rpm, and further under vacuum The slurry for negative electrode was prepared by stirring and mixing at 1,800 rpm for 1.5 minutes.

(3) Measurement of the spinnability of the slurry The spinnability of the positive electrode slurry and the negative electrode slurry obtained above was measured as follows. First, a Zaan cup (Dazai Equipment Co., Ltd., Zaan Bisco City Cup No. 5) having an opening with a diameter of 5.2 mm at the bottom of the container was prepared. With the Zahn cup opening closed, 40 g of the slurry prepared above was poured. When the opening was opened, the slurry flowed out. In this case, the time instant of opening the opening and T _0, the time continued to flow out so as to draw the yarn when the slurry flows measured visually, the time was T _A. Moreover, to continue the measurement from no longer attracted yarn was measured time T _B until the slurry no longer flow out. The measured values T ₀ , T _A and T _B were substituted into the following formula (3) to determine the spinnability. As described above, when the spinnability of the slurry is 30 to 80%, it can be determined that the applicability on the current collector is good.
Spinnability (%) = ((T _A −T ₀ ) / (T _B −T ₀ )) × 100 (3)

5.1.3. Production and Evaluation of Positive Electrode and Negative Electrode (1) Production of Positive Electrode The positive electrode slurry prepared above is uniformly applied to the surface of the current collector made of aluminum foil by a doctor blade method so that the film thickness after drying becomes 110 μm. It was applied and dried at 120 ° C. for 10 minutes. Then, the positive electrode was obtained by pressing with a roll press so that the density of a film | membrane (active material layer) might be 3.0 g / cm < ³ >.

(2) Production of Negative Electrode The negative electrode slurry prepared above was uniformly applied to the surface of a current collector made of copper foil by a doctor blade method so that the film thickness after drying was 110 μm. Dried for minutes. Then, the negative electrode was obtained by pressing using a roll press so that the density of a film | membrane (active material layer) might be 1.5 g / cm < ³ >.

(3) Evaluation of crack rate of electrode plate Each of the positive electrode plate and the negative electrode plate obtained above was cut into 2 cm width × 10 cm length, and the positive electrode plate was bent 100 times along a round bar having a diameter of 2 mm in the width direction. The bending test was repeatedly performed. The size of the crack along the round bar was visually observed and measured, and the crack rate was measured. The crack rate was defined by the following formula (4).
Crack rate (%) =
(Length with cracks (mm) ÷ Total length of electrode plate (mm)) × 100 (4)
The crack rate was evaluated in 5% increments by rounding off to make it easier to clarify the difference. Here, the electrode plate excellent in flexibility and adhesion has a low crack rate. The crack rate is preferably 0%. However, when the electrode plate group is manufactured by winding the positive electrode plate and the negative electrode plate in a spiral shape through a separator, the crack rate is allowed up to 20%. However, when the crack rate is greater than 20%, the electrode plates are easily cut, making it impossible to manufacture the electrode plate group, and the productivity of the electrode plate group is lowered. From this, it is considered that the crack rate is good within 20%.

5.1.4. Assembling and Evaluation of Lithium Ion Battery Cell (1) Assembling of Lithium Ion Battery Cell In the glove box substituted with Ar so that the dew point is -80 ° C. or lower, the negative electrode produced above was punched and molded to a diameter of 15.95 mm Was placed on a bipolar coin cell (trade name “HS flat cell” manufactured by Hosen Co., Ltd.). Next, a separator made of a polypropylene porous membrane punched into a diameter of 24 mm (trade name “Celguard # 2400” manufactured by Celgard Co., Ltd.) was placed, and after injecting 500 μL of an electrolyte solution so that air did not enter, A lithium ion battery cell (power storage device) was assembled by placing the positive electrode manufactured in the above-described method by punching and molding the positive electrode to a diameter of 16.16 mm, and sealing the outer body of the bipolar coin cell with a screw. The electrolytic solution used here is a solution obtained by dissolving LiPF ₆ at a concentration of 1 mol / L in a solvent of ethylene carbonate / ethyl methyl carbonate = 1/1 (mass ratio).

(2) Measurement of rate characteristics, remaining capacity rate, and resistance increase rate The lithium ion battery cell produced above was placed in a thermostatic bath at 25 ° C., and charging was started at a constant current (0.2 C). When the voltage reached 1 V, charging was continued at a constant voltage (4.1 V), and when the current value reached 0.01 C, charging was completed (cut off). Next, discharging was started at a constant current (0.2 C), and the time when the voltage reached 2.5 V was regarded as discharging completion (cut-off) (aging charge / discharge).

The cell after the aging charge / discharge is put in a thermostat at 25 ° C., and charging is started at a constant current (0.2 C). When the voltage reaches 4.1 V, the cell is continuously maintained at a constant voltage (4.1 V). Charging was continued, and charging was completed (cut off) when the current value reached 0.01C. Next, constant current (
The discharge was started at 0.2 C), and when the voltage reached 2.5 V, the discharge was completed (cut-off), and C1 as the value of the discharge capacity (initial) at 0.2 C was measured.

The cell after the discharge capacity (initial) measurement was placed in a constant temperature bath at 25 ° C., charging was started at a constant current (0.2 C), and when the voltage reached 4.1 V, the constant voltage (4.1 V) was continued. The charging was continued at), and the time when the current value reached 0.01 C was defined as the completion of charging (cut-off). Subsequently, the discharge capacity C2 when discharging by a constant current (5.0C) system was measured. And using these measured values, 5C rate characteristic (%) of the lithium ion secondary battery was computed by following formula (5).
5C rate characteristics (%) = (C2 / C1) × 100 (5)
It can be determined that the larger the value of the 5C rate characteristic, the better the output characteristic can be obtained even in the high-speed discharge, but it can be determined that the value is particularly good when the value of the 5C rate characteristic is 60% or more.

  The cell after the discharge capacity (initial) measurement was placed in a constant temperature bath at 25 ° C., charging was started at a constant current (0.2 C), and when the voltage reached 4.1 V, the constant voltage (4.1 V) was continued. The charging was continued at), and the time when the current value reached 0.01 C was defined as the completion of charging (cut-off).

  An EIS measurement ("Electrochemical Impedance Spectroscopy", "electrochemical impedance measurement") was performed on the charged cell, and an initial resistance value EISA was measured.

  Next, the cell in which the initial resistance value EISa was measured was placed in a constant temperature bath at 60 ° C., and charging was started at a constant current (0.2 C). When the voltage reached 4.4 V, the constant voltage (4 4V), charging was continued for 168 hours (overcharge acceleration test).

  After that, the charged cell was placed in a constant temperature bath at 25 ° C., the cell temperature was lowered to 25 ° C., and then discharging was started at a constant current (0.2 C), and the voltage became 2.5V. Was completed (cutoff), and C2 as a value of the discharge capacity at 0.2 C (after the test) was measured.

  The cell having the above discharge capacity (after the test) is placed in a constant temperature bath at 25 ° C., and charging is started at a constant current (0.2 C). When the voltage reaches 4.1 V, the constant voltage (4.1 V) continues. The charging was continued at, and the time when the current value reached 0.01 C was regarded as charging completion (cut-off). Next, discharging was started at a constant current (0.2 C), and the time when the voltage reached 2.5 V was regarded as completion of discharging (cut-off). EIS measurement of this cell was performed, and EISb which is a resistance value after application of thermal stress and overcharge stress was measured.

The respective measured values were substituted into the following formula (6) and the following formula (7) to determine the remaining capacity rate and the resistance increase rate, respectively.
Residual capacity ratio (%) = (C2 / C1) × 100 (6)
Resistance increase rate (%) = ((EISb−EISa) / EISa) × 100 (7)
When this remaining capacity ratio is 75% or more and the resistance increase rate is 300% or less, it can be evaluated that the durability is good.

  In the above measurement conditions, “1C” indicates a current value at which discharge is completed in one hour after constant current discharge of a cell having a certain electric capacity. For example, “0.1 C” is a current value at which discharge is completed over 10 hours, and “10 C” is a current value at which discharge is completed over 0.1 hours.

5.2. Examples 2-9, Comparative Examples 2-3
In the same manner as in Example 1 except that the composition of the monomer and the amount of the initiator were appropriately changed in “5.1.1. Synthesis and Evaluation of Water-Soluble Polymer (A)” in Example 1 above. Then, an aqueous solution (binder composition for electricity storage device S2 to S11) containing a polymer having the composition shown in Table 1 was prepared, and the molecular weight was measured. The results are also shown in Table 1.

  However, the binder composition S10 for electricity storage devices was prepared as follows. After the inside of the separable flask having a volume of 7 L was sufficiently purged with nitrogen, 1050 parts by mass of water was charged and the internal temperature was raised to 70 ° C. Next, a mixed solution of 0.6 parts by mass of sodium persulfate, 110 parts by mass of water, 80 parts by mass of acrylamide, 10 parts by mass of acrylic acid, and 10 parts by mass of ethyl acrylate was added dropwise over 1 hour and reacted at 70 ° C. for 3 hours. Then, a polymer was obtained by further reacting at 90 ° C. for 5 hours. The polymer thus obtained had a gelled reaction system and could not be used as a binder. The aqueous solution containing the polymer thus obtained was designated as a binder composition S10 for an electricity storage device.

Since the initiator was dropped into the reaction system little by little, the initiator concentration was low and it was difficult for the reaction to stop due to decomposition of the initiator, so the water-soluble polymer contained in the binder composition S1 for electricity storage devices Although it is the same composition as the monomer composition of (A), molecular weight became larger than the water-soluble polymer (A) contained in binder composition S1 for electrical storage devices (weight average molecular weight (Mw) is 6x). Is estimated to be greater than 10 ⁶ ).

  Next, in Example 5 “5.1.2. Preparation and evaluation of slurry for positive electrode and negative electrode”, Example 1 was carried out except that the addition amount of the polymer and the type of the active material were those shown in Table 2. Similarly, a positive electrode slurry and a negative electrode slurry were prepared, and the spinnability of the slurry was measured. The results are also shown in Table 2.

  Further, in the same manner as in “5.1.3. Production and evaluation of positive electrode and negative electrode” and “5.1.4. Assembly and evaluation of lithium ion battery cell” in Example 1 above, an electrode and an electricity storage device were produced. And evaluated. The results are also shown in Table 2.

5.3. Evaluation Results of Examples 1 to 9 and Comparative Examples 1 to 3 Table 1 below shows the monomer composition and molecular weight measurement results of the polymers contained in each binder composition for an electricity storage device. Table 2 below shows the compositions of the positive electrode and negative electrode slurries and the evaluation results.

In addition, the abbreviation of each component in Table 1 has the following meaning, respectively.
AMM: acrylamide MAMMA: methacrylamide NMAM: N-methylol acrylamide ATBS: acrylamide t-butyl sulfonic acid AA: acrylic acid MAA: methacrylic acid VS: vinyl sulfonic acid AS: allyl sulfonic acid MAS: Methallylsulfonic acid, MMA: methyl methacrylate, MA: methyl acrylate, BA: n-butyl acrylate, EA: ethyl acrylate, HEMA: hydroxyethyl methacrylate, AN: acrylonitrile, MAN: methacrylonitrile The notation “-” indicates that the corresponding component was not used or the corresponding operation was not performed.

Abbreviations of each component in Table 2 have the following meanings.
NMC (111): manufactured by Umicore, nickel, manganese, lithium cobaltate (nickel (Ni): cobalt (Co): manganese (Mn) is 1: 1: 1), grade name "MX-
10 "
NMC (532): manufactured by Umicore, nickel, manganese, lithium cobaltate (nickel (Ni): cobalt (Co): manganese (Mn) is 5: 3: 2), grade name "TX-10"
・ AB: Acetylene black (manufactured by Denki Black, Denka Black 50% press) ・ Graphite: Hitachi Chemical Co., Ltd., trade name “MAG”
NaVO ₃ : manufactured by Wako Pure Chemical Industries, Ltd., sodium metavanadate (V)

  As apparent from Table 2 above, the slurry for the electricity storage device electrode according to the present invention shown in Examples 1 to 9 is excellent in the spinnability, and the binding property and activity between the current collector and the active material layer are excellent. An excellent electrode having a low crack rate was obtained because of good binding between the materials. In addition, an electricity storage device (lithium ion battery) including these electrodes has excellent charge / discharge rate characteristics and excellent oxidation resistance, and thus has excellent durability.

  On the other hand, the power storage device electrode slurry shown in Comparative Example 1 gave an electrode having a high crack rate. Moreover, in an electrical storage device provided with these electrodes, the charge / discharge durability characteristics were inferior. In the slurry for electricity storage device electrodes shown in Comparative Examples 2 to 3, a good electrode cannot be obtained because the active material layer having a uniform film thickness was not formed due to low spinnability, and good charge / discharge characteristics were obtained. The electricity storage device shown was not obtained.

5.4. Example 10
5.4.1. Preparation of slurry for protective film Titanium oxide (product name “KR380”, manufactured by Titanium Industry Co., Ltd., rutile type, average particle size 0.38 μm) is 20 parts by mass with respect to 100 parts by mass of water. An amount corresponding to 5 parts by mass of the obtained binder composition S1 for an electricity storage device in terms of the water-soluble polymer (A) with respect to the filler was calculated using T.I. K. Mixing and dispersing treatment was performed using a film mix (R) 56-50 type (manufactured by PRIMIX Co., Ltd.) to prepare a slurry for a protective film in which titanium oxide was dispersed. The spinnability of the protective film slurry thus obtained was evaluated in the same manner as in Example 1.

5.4.2. 3. Production of positive electrode Biaxial planetary mixer (product name “TK Hibismix 2P-03” manufactured by PRIMIX Corporation) and binder for electrochemical device electrode (product name “KF polymer # 1120” manufactured by Kureha Co., Ltd.) 0 parts by mass (converted to solid content), 3.0 parts by mass of conductive assistant (manufactured by Denki Kagaku Kogyo Co., Ltd., trade name “DENKA BLACK 50% press product”), LiCoO _{2 having a} particle diameter of 5 μm as a positive electrode active material (Hayashi Kasei) 100 parts by mass (manufactured by Corporation) (solid content conversion) and 36 parts by mass of N-methylpyrrolidone (NMP) were added and stirred at 60 rpm for 2 hours. After adding NMP to the obtained paste to adjust the solid content to 65%, using a stirring defoaming machine (trade name “Awatori Netaro”, manufactured by Shinky Co., Ltd.), 2 minutes at 200 rpm, 1800 rpm The slurry for positive electrode was prepared by stirring and mixing for 5 minutes at 1800 rpm for 1 minute at 1800 rpm. The obtained electrode slurry was uniformly applied to the surface of a current collector made of aluminum foil by a doctor blade method so that the film thickness after drying was 120 μm, followed by drying treatment at 120 ° C. for 20 minutes. Then, the positive electrode was obtained by pressing with a roll press so that the density of an active material layer might be set to 3.0 g / cm < ³ >.

  Next, the protective film slurry prepared above was applied to the surface of the active material layer using a die coating method, and then dried at 120 ° C. for 5 minutes to form a protective film on the surface of the active material layer. The formed protective film had a thickness of 3 μm. For the positive electrode thus obtained, the crack rate of the electrode plate (protective film) was evaluated in the same manner as in Example 1.

5.4.3. Negative electrode Biaxial planetary mixer (product name “TK Hibismix 2P-03” manufactured by PRIMIX Corporation), 4 parts by mass of polyvinylidene fluoride (PVDF) (in terms of solid content), and 100 parts by mass of graphite as a negative electrode active material ( Solid conversion), 80 parts by mass of N-methylpyrrolidone (NMP) were added, and the mixture was stirred at 60 rpm for 1 hour. Then, after adding 20 parts by mass of NMP, using a stirring defoaming machine (product name “Awatori Netaro” manufactured by Shinky Co., Ltd.) for 2 minutes at 200 rpm, then for 5 minutes at 1,800 rpm, further vacuum Below, the slurry for negative electrodes was prepared by stirring and mixing for 1.5 minutes at 1,800 rpm.

The negative electrode slurry prepared above was uniformly applied to the surface of a current collector made of copper foil by a doctor blade method so that the film thickness after drying was 110 μm, and dried at 120 ° C. for 20 minutes. Then, the negative electrode was obtained by pressing using a roll-press machine so that the density of a film | membrane may be 1.5 g / cm < ³ >.

5.4.4. Assembly of Lithium Ion Battery Cell A bipolar coin cell (Hosen Co., Ltd.) obtained by punching and molding the negative electrode produced above to a diameter of 15.95 mm in an Ar-substituted glove box with a dew point of −80 ° C. or lower. And product name “HS flat cell”). Next, a separator made of a polypropylene porous membrane punched into a diameter of 24 mm (trade name “Celguard # 2400” manufactured by Celgard Co., Ltd.) was placed, and after injecting 500 μL of an electrolyte solution so that air did not enter, The positive electrode manufactured in the above is punched and molded to a diameter of 16.16 mm and placed so that the protective film formed on the positive electrode and the separator face each other, and the outer body of the bipolar coin cell is closed with a screw and sealed. Thus, a lithium ion battery cell (electric storage device) was assembled. The electrolytic solution used here is a solution obtained by dissolving LiPF ₆ at a concentration of 1 mol / L in a solvent of ethylene carbonate / ethyl methyl carbonate = 1/1 (mass ratio). The power storage device thus obtained was evaluated for rate characteristics, remaining capacity rate, and resistance increase rate in the same manner as in Example 1.

5.5. Examples 11-17, Comparative Examples 4-6
A protective film in the same manner as in Example 10 except that the binder composition for an electricity storage device used in Example 10 was changed to that shown in Table 3 and the filler used was that shown in Table 3. Slurry was prepared and its spinnability was evaluated. Further, a positive electrode was produced in the same manner as in Example 10 except that the protective film slurry used in Example 10 was that shown in Table 3, and the crack rate was evaluated. Furthermore, after producing a negative electrode in the same manner as in Example 10, an electricity storage device was manufactured, and rate characteristics, remaining capacity ratio, and resistance increase rate were similarly evaluated. These evaluation results are also shown in Table 3.

5.6. Examples 18-20, Comparative Examples 7-9
In Example 10 above, the binder composition for an electricity storage device used was changed to that shown in Table 4 and the protection was performed in the same manner as in Example 10 except that the filler used was that shown in Table 4. A membrane slurry was prepared and evaluated for spinnability. The evaluation results are also shown in Table 4.

  Next, a negative electrode is prepared in the same manner as in Example 10, and the obtained protective film slurry is applied to the surface of the active material layer of the negative electrode using a die coating method, and then dried at 120 ° C. for 5 minutes. Thus, a protective film was formed on the surface of the active material layer. For the negative electrode thus obtained, the crack rate of the electrode plate (protective film) was evaluated in the same manner as in Example 10. The evaluation results are also shown in Table 4.

  Further, the battery was charged in the same manner as in Example 10 except that the positive electrode before forming the protective film produced in Example 10 was used as the positive electrode, and the negative electrode with protective film obtained above was used as the negative electrode. A device was manufactured (however, the negative electrode protective film and the separator were placed so as to face each other), and the rate characteristics, the remaining capacity rate, and the resistance increase rate were similarly evaluated. These evaluation results are also shown in Table 4.

5.7. Example 21
The wire bar was prepared by drying the protective film slurry prepared in Example 10 on one side of a separator made of a polypropylene porous film (trade name “Celguard # 2400” manufactured by Celgard Co., Ltd.) so that the thickness after drying was 10 μm. And then dried at 90 ° C. for 20 minutes to obtain a separator with a protective film. The separator with protective film thus obtained was evaluated for the crack rate of the protective film in the same manner as in Example 10. The evaluation results are also shown in Table 5.

  Furthermore, using the positive electrode before forming the protective film produced in Example 10 as the positive electrode and the negative electrode produced in Example 10 as the negative electrode, the protective film surface of the separator with protective film obtained above was An electricity storage device was fabricated in the same manner as in Example 10 with the positive electrode side, and the rate characteristics, the remaining capacity rate, and the resistance increase rate were similarly evaluated. The results are also shown in Table 5.

5.8. Examples 22-28, Comparative Examples 10-12
In Example 21 above, a separator with a protective film was prepared in the same manner as in Example 21 except that the slurry for protective film was prepared by changing the binder composition and filler for the electricity storage device used to those shown in Table 5. A positive electrode, a negative electrode, and an electricity storage device were manufactured and evaluated in the same manner. The results are also shown in Table 5.

5.9. Examples 29-31, Comparative Examples 13-15
In Example 21, the binder composition for an electricity storage device and the filler used were changed to those shown in Table 6 to prepare a slurry for the protective film, so that the protective film surface of the separator with the protective film was on the negative electrode side. A separator with a protective film, a positive electrode, a negative electrode, and an electricity storage device were produced in the same manner as in Example 21 except that the evaluation was performed in the same manner. The results are also shown in Table 6.

5.10. Evaluation Results of Examples 10 to 31 and Comparative Examples 4 to 15 Tables 3 to 6 below show the composition of the slurry for the protective film and each evaluation result.

The fillers described in Tables 3 to 6 are as follows.
Titanium oxide: The product name “KR380” (manufactured by Titanium Industry Co., Ltd., rutile type, average particle size 0.38 μm) is used as it is, or is ground in a mortar with the product name “KR380” and used with a sieve. By classification, titanium oxides having an average particle diameter of 0.08 μm and 0.12 μm were prepared and used.
Aluminum oxide: Product name “AKP-3000” (manufactured by Sumitomo Chemical Co., Ltd., average particle size 0.74 μm), or product name “AL-160SG-3” (manufactured by Showa Denko KK, average particle size 0.98 μm) Was used.
Zirconium oxide: Product name “UEP zirconium oxide” (Daiichi Rare Element Chemical Industries, Ltd., average particle size 0.67 μm)
Silica: The product name “Sea Hoster (R) KE-S50” (manufactured by Nippon Shokubai Co., Ltd., average particle size 0.54 μm) was used.
Magnesium oxide: Product name “PUREMAG® FNM-G” (manufactured by Tateho Chemical Industry Co., Ltd., average particle size 0.50 μm)

  As is apparent from Tables 3 to 6, the slurry for protective film according to the present invention shown in Examples 10 to 31 gave an excellent protective film having excellent spinnability and a low crack rate. In addition, an electricity storage device (lithium ion battery) including an electrode with a protective film or a separator with a protective film has good charge / discharge rate characteristics and good oxidation resistance, and therefore has excellent charge / discharge durability characteristics. It was.

  The present invention is not limited to the above embodiment, and various modifications can be made. The present invention includes configurations that are substantially the same as the configurations described in the embodiments (for example, configurations that have the same functions, methods, and results, or configurations that have the same objects and effects). The present invention also includes a configuration in which a non-essential part of the configuration described in the above embodiment is replaced with another configuration. Furthermore, the present invention includes a configuration that achieves the same effects as the configuration described in the above embodiment or a configuration that can achieve the same object. Furthermore, the present invention includes a configuration obtained by adding a known technique to the configuration described in the above embodiment.

Claims (12)

A slurry for an electricity storage device containing 1 to 10 parts by mass of a water-soluble polymer (A) with respect to 100 parts by mass of an active material,
The slurry for an electricity storage device, wherein the proportion of the repeating unit derived from (meth) acrylamide contained in 100 parts by mass of the water-soluble polymer (A) is 40 to 100 parts by mass.   The slurry for electrical storage devices containing 1-10 mass parts of water-soluble polymers (A) which have a repeating unit derived from (meth) acrylamide with respect to 100 mass parts of fillers.   The slurry for electrical storage devices of Claim 2 whose ratio of the repeating unit derived from (meth) acrylamide contained in 100 mass parts of said water-soluble polymers (A) is 40-100 mass parts.   4. The slurry for an electricity storage device according to claim 2, wherein the filler is at least one particle selected from the group consisting of silica, titanium oxide, aluminum oxide, zirconium oxide, and magnesium oxide.   The slurry for an electricity storage device according to any one of claims 1 to 4, which does not contain a water-insoluble polymer.   The water-soluble polymer (A) is a repeating unit derived from at least one selected from the group consisting of an acid having a polymerizable unsaturated double bond, an unsaturated carboxylic acid ester, and an α, β-unsaturated nitrile compound. The slurry for an electricity storage device according to any one of claims 1 to 5, further comprising:   The slurry for an electricity storage device according to any one of claims 1 to 6, wherein the water-soluble polymer (A) has a weight average molecular weight (Mw) of 300,000 to 6,000,000.   The slurry for electrical storage devices according to any one of claims 1 to 7, wherein the water-soluble polymer (A) has a weight average molecular weight (Mw) / number average molecular weight (Mn) of 3 to 30.   An electricity storage device electrode comprising: a current collector; and a layer formed by applying and drying the electricity storage device slurry according to claim 1 on a surface of the current collector. A current collector, and an active material layer formed on the surface of the current collector,
Furthermore, an electrical storage device electrode provided with the layer formed by apply | coating and drying the slurry for electrical storage devices as described in any one of Claims 2 thru | or 4 on the surface of the said active material layer.   The separator which equips the surface with the layer formed by apply | coating and drying the slurry for electrical storage devices as described in any one of Claims 2 thru | or 4.   An electricity storage device comprising at least one of the electricity storage device electrode according to claim 9 or claim 10 and the separator according to claim 11.