WO2013100023A1 - Heat-resistant resin, adhesive agent, insulating adhesive layer, separator, solid electrolyte, and electrical storage device - Google Patents

Abstract

Provided is a heat-resistant resin for electrical storage devices that can be employed in surface mounting by reflow soldering. Used is either (a) a homopolymer or copolymer for which the constituent monomers are an acrylic acid ester in which R₁ has at least one carbon, the R₁ being bonded by the carbon with an ester bond, and in which the carbon bonded by the ester bond (hereinafter the "carbon of the 1-position in R₁") is a primary or secondary carbon, or an acrylic acid in which R₁ is hydrogen; or (b) a copolymer for which the constituent monomers are an acrylic acid ester and/or acrylic acid and a methacrylic acid ester and/or methacrylic acid, wherein the constituent monomers are an acrylic acid ester/methacrylic acid ester in which R₁ has at least one carbon, the R₁ being bonded by the carbon with an ester bond, and in which the carbon of the 1-position of the R₁ is a primary or secondary carbon, or an acrylic acid/methacrylic acid in which R₁ is a hydrogen, and wherein the sum of the methacrylic acid ester and methacrylic acid in mole percent is 30% or less.

Description

Heat resistant resin, adhesive, insulating adhesive layer, separator, solid electrolyte, and electricity storage device

The present invention relates to a heat resistant resin, and more specifically, a heat resistant resin suitable for use in a separator or an insulating adhesive layer constituting an electricity storage device, an adhesive using the same, an insulating adhesive layer, a separator, a solid electrolyte In addition, the present invention relates to a power storage device including a separator using the heat resistant resin and an insulating adhesive layer.

For example, separators for power storage devices such as lithium ion secondary batteries, lithium ion capacitors, electric double layer capacitors, and insulating adhesive layers have desired characteristics regarding heat resistance, adhesiveness, oxidation resistance, reduction resistance, etc. Various resins provided with are used.

Examples of such a resin include (A) 10 to 40 parts by weight of a structural unit derived from a monomer in which a carbonate group is introduced into the epoxy group of a (meth) acrylate monomer having an epoxy group, and (B) 10 to 10 structural units derived from acrylonitrile. 30 parts by weight of an acrylic resin containing 30 to 80 parts by weight of structural units derived from (C) alkyl (meth) acrylate monomer,
(A) 10 to 40 parts by weight of structural unit derived from (meth) acrylate monomer having epoxy group, (B) 10 to 30 parts by weight of structural unit derived from acrylonitrile, and (C) structural unit 30 derived from alkyl (meth) acrylate monomer An acrylic resin containing ˜80 parts by weight as a component, wherein the epoxy resin is present in the side chain of the acrylic resin and a carbonate group is added to the epoxy group has been proposed (Patent) Reference 1).

And (A ′) 60 to 99% by mass of (meth) acrylate-derived structural units based on the total mass of the acrylic polymer; and (B ′) 1 to 40% by mass on the total mass of the acrylic polymer An acrylic polymer containing a structural unit having a carbon-carbon double bond in the chain, having a mass average molecular weight of 10,000 to 25,000 and a molecular weight dispersity of 1.5 to 3.0 has been proposed (see Patent Document 2).

Further, 1 to 95 mol% of the structural unit 1 derived from (meth) acrylate, 1 to 60 mol% of the (meth) acrylate structural unit 2 having a hydroxyl group, and di (meth) acrylate having a polymerizable functional group An acrylic polymer having 1 to 60 mol% of the structural unit 3, wherein the acrylic polymer has a mass average molecular weight of 1,000 to 100,000, and is a cross-link at a di (meth) acrylate moiety Has been proposed that enables the preparation of a gel electrolyte (see Patent Document 3).

Further, 1 to 95 mol% of the structural unit 1 derived from (meth) acrylate, 1 to 60 mol% of the (meth) acrylate structural unit 2 having a hydroxyl group, and (meth) acrylate structural unit 3 having a cyano group Acrylic polymer having 1 to 60 mol% of the polymer and 1 to 60 mol% of the di (meth) acrylate structural unit 4 having a polymerizable functional group, wherein the acrylic polymer has a mass average molecular weight of 1,000 to 100,000. There has been proposed a polymer that can produce a gel electrolyte by crosslinking at a di (meth) acrylate moiety (see Patent Document 4).

Further, 1 to 95 mol% of structural units derived from (meth) acrylate represented by the general formula (1), 1 to 60 mol% of structural units having a hydroxyl group represented by the general formula (2), 1 to 60 mol% of the structural unit represented by 3), 1 to 60 mol% of the structural unit represented by the general formula (4), and 1 to 60 structural units having a polymerizable functional group represented by the general formula (5) An acrylic polymer containing a mol%, wherein the acrylic polymer has a mass average molecular weight of 1,000 to 100,000 has been proposed (see Patent Document 5).

Further, (A ′) a structural unit derived from 35 to 99% by mass of (meth) acrylate with respect to the total mass of the acrylic polymer; An acrylic polymer having a structural unit having a double bond in a chain, a mass average molecular weight of 1,000 to 100,000, and a molecular weight dispersity of 1.3 to 4.0, and producing a gel electrolyte by crosslinking What has been made possible has been proposed (see Patent Document 6).

Further, the structural unit 1 derived from the (meth) acrylate represented by the general formula (1) is 1 to 99 mol%, and the structural unit 2 having an epoxy group represented by the general formula (2) is 1 to 99 mol%. An acrylic polymer having a weight average molecular weight of 1,000 to 100,000 has been proposed (see Patent Document 7).

Moreover, it contains a heat resistant resin and two or more fillers, and the first largest value among the values obtained by measuring the average particle diameter of the particles constituting each of the two or more fillers. D ₁ is a porous film having a D ₂ / D ₁ value of 0.15 or less, where the second largest value is D _2, and uses a nitrogen-containing aromatic polymer as a heat-resistant resin. It has been proposed (see Patent Document 8).

As described above, in each of the above patent documents, in Patent Documents 1 to 7, a copolymer made of an acrylic acid derivative or a methacrylic acid derivative made of various monomers is used as a binder for the separator. References 1 to 7 do not mention the composition of an acrylic binder having a particularly high heat resistance. With compositions such as those described in Patent References 1 to 7, the binder resin is decomposed at high temperatures such as reflow. However, there is a concern about degradation of device characteristics due to decomposition products. Further, in an electricity storage device using a package, the decomposition product of the binder is vaporized due to high temperature, which may cause a problem that the package internal pressure is increased and the package is deformed.

Further, in order to realize a separator having heat resistance, in Patent Document 8 which proposes a porous film containing a heat resistant resin and two or more fillers (ceramics), as a heat resistant resin (binder), polyimide or Polyamide etc. are mentioned, and these have heat resistance which does not decompose even in reflow.

However, these resins are generally expensive and not only have cost problems, but also have a problem that the degree of freedom in the process is low due to restrictions on the solvent in which these resins can be dissolved. . Furthermore, regarding the resin structure, since there is no diversity like acrylic resin and methacrylic resin, it is actually difficult to design a binder resin according to the required characteristics.

JP 2006-335971 A JP 2008-156629 A JP 2008-285666 A JP 2008-285668 A JP 2009-102608 A International Publication No. 2007/086396 JP 2009-256570 A JP 2008-266593 A

The present invention solves the above-mentioned problems, does not thermally decompose even at reflow soldering temperature (260 ° C.), can maintain the given shape and structure, and is compatible with surface mounting by reflow soldering. Heat-resistant resin suitable for use in separators and insulating adhesive layers of electrical storage devices, adhesives using the same, insulating adhesive layers, separators, solid electrolytes, separators using the above heat-resistant resins, and insulating properties It aims at providing the electrical storage device formed by forming an adhesive layer etc.

The resin constituting separators and insulating adhesive layers of power storage devices such as lithium ion secondary batteries, lithium ion capacitors, and electric double layer capacitors has sufficient oxidation resistance with respect to the positive electrode potential used for power storage devices, negative electrode It is required to have sufficient reduction resistance against electric potential.
In addition, a resin material used for an electricity storage device that supports surface mounting by reflow soldering is required to be a material that does not thermally decompose even at a reflow temperature (for example, 260 ° C.).
However, materials known to satisfy these conditions are limited, and fluororesins such as PTFE (polytetrafluoroethylene) have been mainly used.

Under these circumstances, the inventors have studied a resin material having sufficient oxidation resistance with respect to the positive electrode potential and sufficient reduction resistance with respect to the negative electrode potential used in the electricity storage device, and has developed acrylic acid or acrylic resin. Among acid esters, homopolymers and copolymers having methacrylic acid or methacrylic acid esters as constituent monomers, those satisfying a predetermined condition are sufficient in oxidation resistance with respect to the positive electrode potential used in the electricity storage device, and the negative electrode It has been found that it has sufficient reduction resistance against electric potential and has thermal decomposition resistance that does not thermally decompose even at a reflow temperature (eg, 260 ° C.).
And based on this knowledge, further experiment and examination were carried out, and the present invention was completed.

That is, the heat resistant resin of the present invention is
It is characterized by containing at least one of the following (a) and (b) as a main component.
(a) R ₁ represented by the chemical formula (1) has at least one carbon, the R ₁ is bonded to the ester bond represented by the chemical formula (1) and the carbon, and the carbon (hereinafter referred to as the carbon bonded to the ester bond). acrylic acid esters and "carbon of 1-position of R _1") is a primary or secondary, or a homopolymer or co-R ₁ represented by the chemical formula (1) is a constituent monomer of acrylic acid is hydrogen Polymer (b) A copolymer having at least one of acrylic acid ester and acrylic acid and at least one of methacrylic acid ester and methacrylic acid as a constituent monomer, wherein the constituent monomer is R represented by chemical formula (1) ₁ has at least one carbon, R ₁ is bonded by the carbon ester bond represented by the chemical formula (1), acrylic acid ester carbon at the 1-position of R ₁ is a primary or secondary, methacrylic Ester, formula (1) are shown acrylate R ₁ is hydrogen, a methacrylic acid, a copolymer mol% of the sum of methacrylic acid esters and methacrylic acid constituting the copolymer is not more than 30%

[In the formula (1), R is H or CH ₃ : R ₁ is H or a chemical species having at least one carbon]

The heat-resistant resin of the present invention is
At least one homopolymer included in the group of homopolymers defined in (a),
At least one copolymer included in the group of copolymers defined in (a) above,
It may be a mixture of at least two selected from the group consisting of at least one copolymer included in the group of copolymers defined in (b).

The heat resistant resin of the present invention preferably has a thermal decomposition temperature exceeding 260 ° C.
According to the present invention, it is possible to realize a heat-resistant resin having a thermal decomposition temperature exceeding 260 ° C. By using this heat-resistant resin, for example, by forming a separator or an insulating adhesive layer, reflow soldering It is possible to obtain an electricity storage device that supports surface mounting by attaching.

When the heat-resistant resin has the basic requirements of the present invention, for example, by controlling the ratio of acrylic resin and methacrylic resin, or by selecting an appropriate side chain structure The pyrolysis temperature can easily be raised above 260 ° C.

Further, the HOMO of the constituent monomer is preferably −8.40 eV or less.
When the heat-resistant resin of the present invention is used as, for example, a binder resin for a positive electrode of an electricity storage device, it is necessary to have oxidation resistance because it is exposed to an oxidizing atmosphere, but is not exposed to a reducing atmosphere, In particular, since reduction resistance is not required, it is not necessary to define LUMO. Therefore, when the HOMO of the constituent monomer is −8.40 eV or less, it can be used without any particular problem for a positive electrode binder resin of an electricity storage device having a relatively low operating positive electrode potential.

The HOMO of the constituent monomer is more preferably −10.71 eV or less.
When the heat-resistant resin of the present invention has the requirement that the HOMO of the constituent monomer is −10.71 eV or less, the storage device such as a lithium ion secondary battery or an electric double layer capacitor having a high operating positive electrode potential is used. It can also be used as a positive electrode binder resin.

Further, the LUMO of the constituent monomer is preferably 2.70 eV or more.
When using the heat resistant resin of the present invention as, for example, a binder resin for a negative electrode of an electricity storage device, it is necessary to have reduction resistance because it is exposed to a reducing atmosphere, but it is not exposed to an oxidizing atmosphere, In particular, since oxidation resistance is not required, it is not necessary to define HOMO. Accordingly, when the LUMO of the constituent monomer has a requirement of 2.70 eV or more, it can be used without any particular problem for the negative electrode binder resin of an electricity storage device having a relatively high operating negative electrode potential.

The LUMO of the constituent monomer is more preferably 2.77 eV or more.
In addition, when the heat-resistant resin of the present invention has a requirement that the LUMO of the constituent monomer is 2.77 eV or more, an electricity storage device such as a lithium ion secondary battery or an electric double layer capacitor having a low operating negative electrode potential It can also be used as a negative electrode binder resin.

The constituent monomers preferably have a HOMO of −8.40 eV or less and a LUMO of 2.70 eV or more.
When the constituent monomers have the requirements that the HOMO is −8.40 eV or less and the LUMO is 2.70 eV or more, since both the oxidation resistance and the reduction resistance are provided, the electricity storage device having a relatively low energy density The heat-resistant resin of the present invention can be used for the separator and the insulating adhesive layer that are bonded to both the negative electrode and the positive electrode that constitute the material.

More preferably, the constituent monomers have a HOMO of 10.71 eV or less and a LUMO of 2.77 eV or more.
When the constituent monomers have requirements of HOMO of -10.71 eV or less and LUMO of 2.77 eV or more, a separator constituting a power storage device such as a lithium ion secondary battery or an electric double layer capacitor having a high energy density The heat resistant resin of the present invention can be used for the insulating adhesive layer.

Moreover, the heat resistant resin of this invention can be set as the structure which mix | blended the inorganic fine particle.
By containing inorganic fine particles, for example, it becomes possible to impart high liquid content, so that when the heat-resistant resin of the present invention is used for a separator or an insulating adhesive layer of an electricity storage device, the production of the electricity storage device is performed. In the process, when the electrolyte solution is injected and impregnated into a laminate formed by laminating the positive electrode layer and the negative electrode layer via the separator and the insulating adhesive layer, the time required for the impregnation is shortened and the productivity is improved. It becomes possible to make it.
In addition, the addition of inorganic fine particles increases the elasticity of separators, insulating adhesive layers, etc., and can improve reliability by preventing deformation due to external forces and the accompanying short circuit caused by contact between the positive and negative electrode layers. it can.

The heat-resistant resin of the present invention is preferably used for an electricity storage device, and is preferably used for an electricity storage device that supports mounting by reflow soldering.
As described above, the heat-resistant resin of the present invention has sufficient heat resistance, and when used in an electricity storage device that supports mounting by reflow soldering, it is possible to perform efficient mounting and reliability. Can be provided.
Furthermore, in the case of a heat-resistant resin having oxidation resistance and / or reduction resistance with the requirements of HOMO and LUMO, it forms important elements that constitute an electricity storage device such as a binder for electrodes, a separator, and an insulating adhesive layer. It can use suitably as a material for doing.

The power storage device is preferably one type selected from the group consisting of a lithium ion secondary battery, a lithium ion capacitor, an electric double layer capacitor, a sulfide solid state battery, an oxide solid state battery, and a thin film battery.
The heat-resistant resin of the present invention can be used for various power storage devices, and in particular for lithium ion secondary batteries, lithium ion capacitors, electric double layer capacitors, sulfide solid state batteries, oxide solid state batteries, and thin film batteries. It can be used suitably.

Also, the adhesive of the present invention is characterized by using the above heat-resistant resin of the present invention.

In the insulating adhesive layer of the present invention, the positive electrode layer and the negative electrode layer are laminated so as to face each other via the insulating adhesive layer in a predetermined region, and face each other via a separator in the other predetermined region. And an insulating adhesive layer used in an electricity storage device having a structure in which the positive electrode layer and the negative electrode layer are bonded via the insulating adhesive layer,
Using a heat resistant resin in which HOMO of the constituent monomer is −8.40 eV or less and LUMO is 2.70 eV or more, or HOMO of the constituent monomer is −10.71 eV or less and LUMO is 2.77 eV or more. It is characterized by being manufactured.

The separator of the present invention is a separator used for an electricity storage device having a laminate in which a positive electrode layer and a negative electrode layer are laminated via a separator, and the constituent monomer has a HOMO of −8. 40 eV or less, LUMO is 2.70 eV or more, or is made using a heat-resistant resin having a HOMO of 10.71 eV or less and a LUMO of 2.77 eV or more. It is said.

In the solid electrolyte of the present invention, the HOMO of the constituent monomer and the constituent monomer is −8.40 eV or less, the LUMO is 2.70 eV or more, or the HOMO of the constituent monomer is −10.71 eV or less. And a heat-resistant resin having a LUMO of 2.77 eV or more.

Further, in the electricity storage device of the present invention, the positive electrode layer and the negative electrode layer are laminated so as to oppose each other via an insulating adhesive layer in a predetermined region, and so as to oppose each other via a separator in other predetermined regions. An electricity storage device having a structure in which the positive electrode layer and the negative electrode layer are bonded via the insulating adhesive layer, wherein the insulating adhesive layer of the present invention is used as the insulating adhesive layer. It is characterized by having.

Further, the electricity storage device of the present invention has a structure in which a positive electrode layer and a negative electrode layer are stacked via a separator, and the positive electrode layer and the negative electrode layer in contact with the separator are directly bonded to the separator. An electricity storage device with a body,
An electricity storage device comprising the separator of the present invention as the separator.

The electricity storage device of the present invention can be configured as one selected from the group consisting of a lithium ion secondary battery, a lithium ion capacitor, and an electric double layer capacitor.
As described above, the heat-resistant resin of the present invention has characteristics such as oxidation resistance and / or reduction resistance and heat resistance. Therefore, by using the heat-resistant resin of the present invention, the heat-resistant resin has good characteristics. A highly reliable lithium ion secondary battery, a lithium ion capacitor, and an electric double layer capacitor can be provided.

The heat-resistant resin of the present invention having the above-mentioned configuration has heat resistance, and is generally not thermally decomposed even in the reflow soldering process, so that the structure is maintained, so that it can be used for surface mounting by reflow soldering. It can be suitably used as a resin for use in electrical storage devices such as the electric double layer capacitor, lithium ion secondary battery, lithium ion capacitor, sulfide solid state battery, oxide solid state battery, and thin film battery.
In the present invention, the fact that thermal decomposition does not occur even in the reflow soldering process is not limited to literally no thermal decomposition at all, and it causes deterioration of characteristics that are particularly problematic even after the reflow process. This means that it is as stable as possible.

Further, as described above, the heat-resistant resin of the present invention has characteristics such as oxidation resistance and / or reduction resistance, heat resistance, etc., so that it is widely used for adhesives used in the manufacture of power storage devices. Can do.

The insulating adhesive layer of the present invention is the heat resistant resin of the present invention, wherein the constituent monomer has a HOMO of −8.40 eV or less, a LUMO of 2.70 eV or more, or a constituent monomer has a HOMO of − Since it is produced using a heat-resistant resin having 10.71 eV or less and LUMO of 2.77 eV or more, the necessary heat resistance, oxidation resistance, reduction resistance as an insulating adhesive layer used in an electricity storage device Therefore, it is possible to provide a highly reliable power storage device that supports surface mounting by reflow soldering.

The separator of the present invention is a separator used for an electricity storage device including a laminate having a structure in which a positive electrode layer and a negative electrode layer are laminated via a separator, and a constituent monomer has a HOMO of −8.40 eV. Hereinafter, LUMO is 2.70 eV or more, or it is produced using a heat-resistant resin whose constituent monomer has HOMO of −10.71 eV or less and LUMO of 2.77 eV or more. As a separator used in the above, it has necessary heat resistance, oxidation resistance, and reduction resistance, and can provide a highly reliable power storage device corresponding to surface mounting by reflow soldering.

The solid electrolyte of the present invention comprises a powdered electrolyte and the heat-resistant resin of the present invention (whether the constituent monomer has a HOMO of −8.40 eV or less and a LUMO of 2.70 eV or more, or the constituent monomer has a HOMO of -10.71 eV or less and a LUMO having a heat resistance resin having a LUMO of 2.77 eV or more), it has heat resistance, oxidation resistance, reduction resistance, and excellent shape retention. A solid electrolyte having high characteristics and reliability can be provided.

It is a figure which shows the result of the TG (thermogravimetry) measurement performed in order to investigate the thermal decomposition temperature of an acrylic type and a methacrylic type homopolymer. It is a figure which shows the result of the TG measurement performed in order to investigate the thermal decomposition temperature of the copolymer of acrylic acid ester and methacrylic acid ester. It is a figure which shows the result of the TG measurement performed in order to investigate the thermal decomposition temperature of resin from which a side chain structure differs. FIG. 2 is a diagram showing a state in which an active material layer is formed on an active material current collector layer in one step of a method for manufacturing an electricity storage device according to an example of the present invention, wherein (a) is a plan view, (b) Is a front sectional view. It is a figure which shows the state which formed the separator layer so that an active material layer might be covered on the electrical power collector layer shown in FIG. 4, Comprising: (a) is a top view, (b) is front sectional drawing. (a) is a figure which shows the printing body which printed the insulating contact bonding layer around the separator layer shown in FIG. 5, (a) is a top view, (b) is front sectional drawing. FIG. 7 is a diagram illustrating a process of punching the printed body of FIG. 6 into a predetermined shape, where (a) is a plan view showing the position of a cutting line of the printed body, and (b) is a positive electrode layer obtained by punching the printed body FIG. 4C is a front sectional view showing a negative electrode layer obtained by punching a printed body. (a) is a front sectional view showing a step of forming a laminate by laminating and adhering the positive electrode layer and the negative electrode layer shown in FIG. 7 with the surface on which the insulating adhesive layer is printed facing each other, (b) FIG. 3 is a front sectional view showing the laminate obtained in (a). It is front sectional drawing which shows the electric double layer capacitor (cell) formed by accommodating the laminated body shown in FIG. 8 in a package, inject | pouring electrolyte solution, and sealing.

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

In the heat-resistant resin of the present invention, (a) R ₁ represented by the chemical formula (1) has at least one carbon, R ₁ is bonded to the ester bond represented by the chemical formula (1) and the carbon, and R ₁ A homopolymer or copolymer having a constituent monomer of acrylic acid ester in which the carbon at the 1-position is primary or secondary, or acrylic acid in which R ₁ is hydrogen represented by chemical formula (1), or (b ) A copolymer having at least one of acrylic acid ester and acrylic acid and at least one of methacrylic acid ester and methacrylic acid as a constituent monomer, wherein the constituent monomer has an R ₁ of at least 1 in the chemical formula (1). R ₁ is bonded to the ester bond represented by the chemical formula (1) by the above carbon, and the carbon at the 1-position of R ₁ is primary or secondary, or R represented by the chemical formula (1) acrylic acid ₁ is hydrogen, meta An acrylic acid, those containing copolymer mol% of the sum of methacrylic acid esters and methacrylic acid constituting the copolymer is 30% or less, as major component.

[In the formula (1), R is H or CH ₃ : R ₁ is H or a chemical species having at least one carbon]

The heat-resistant resin of the present invention having the above-described structure has sufficient heat resistance, and maintains its structure without being thermally decomposed even in a normal reflow soldering process. This is for the reason described below.

[Side chain degradability]
Regarding the decomposability of the side chain of the acrylic ester or methacrylic ester used in the heat resistant resin of the present invention, R ₁ represented by the chemical formula (1) has at least one carbon, and R ₁ has the chemical formula (1 ) And the above-mentioned carbon and when the carbon at the 1-position of R ₁ is primary or secondary, even at 260 ° C. of reflow soldering temperature (hereinafter “reflow temperature”) Side chains do not break down. On the other hand, when the carbon at the 1-position of R ₁ is tertiary, side chain decomposition occurs from about 150 ° C., and therefore cannot be used as a resin for an electricity storage device that is scheduled to be mounted by reflow soldering.

Thus, the decomposability of the side chain depends on the series of carbons bonded to the ester bond. The stability of the carbocation generated when the bond between the ester bond and the carbon bonded thereto is broken is the series of carbons. It is thought that this is due to dependence on The inventors presume that this is due to the fact that the lower the carbon series, the more unstable the carbocation generated when the bond is cleaved, so that the energy required for bond cleavage increases, and this is confirmed by experiments described later. As a result, the result according to the guess was obtained.

[Main chain degradability]
The methacrylic acid skeleton is more easily decomposed than the acrylic acid skeleton. Actually, a homopolymer of a methacrylic acid ester is decomposed around 130 ° C. and cannot be used because it easily decomposes at a high temperature such as reflow. On the other hand, an acrylic resin consisting only of an acrylic acid skeleton has high heat resistance that does not decompose at 260 ° C.
Therefore, the heat resistant resin of the present invention can be constituted by using an acrylic resin.

On the other hand, an acrylic resin has a low glass transition temperature, and it is not always easy to obtain a heat-resistant resin (particularly an adhesive) having no tack. Therefore, the introduction of a methacrylic acid skeleton into the acrylic acid skeleton was studied so that a heat resistant resin having a high glass transition temperature could be obtained.
As a result of experiments, although the thermal decomposability increases with the introduction of the methacrylic acid skeleton (the thermal decomposability decreases), the sum of the mol% of methacrylic acid and methacrylic acid ester monomer constituting the polymer is 30% or less. In some cases, it was confirmed that it did not decompose even at a reflow temperature of 260 ° C. and showed sufficient heat resistance for reflow.

Since the reactivity of acrylic acid ester and methacrylic acid ester is relatively similar, they can be easily copolymerized. By selecting the monomer and copolymer composition ratio, a wide range of glass transition temperatures can be obtained. Can be designed. That is, it is a resin material that is very effective in that a resin design having a composition corresponding to the bonding temperature required for use as an adhesive material can be performed. For example, when an adhesive material having no instantaneous adhesiveness (tack) is required, it is possible to easily control the glass transition temperature by copolymerization so that the glass transition temperature becomes room temperature or higher.
The advantages of using acrylic resin and methacrylic resin will be described below.

[Features of heat-resistant resins using acrylic and methacrylic resins]
Examples of heat-resistant resins include fluororesins such as PTFE, PVDF, and PVDF-HFP (a copolymer of PVDF and hexafluoropropylene (HFP)), and engineering plastics such as polyimide and polyamide. On the other hand, an acrylic resin and a methacrylic resin are advantageous in that they are cheaper than these.

Furthermore, high heat-resistant resins such as fluororesins such as PTFE, PVDF, PVDF-HFP (copolymer of PVDF and hexafluoropropylene (HFP)) as described above, engineering plastics such as polyimide and polyamide are highly stable. In addition, since the solubility in the solvent is poor and an expensive solvent is required, not only the cost is increased but also the production process is limited. In contrast, acrylic resins and methacrylic resins are soluble in many solvents, and not only can an inexpensive solvent be selected, but also a solvent according to the process can be selected. There are many options.

Also, since the side chain structures of acrylic resins and methacrylic resins are diverse and have different physical properties such as glass transition temperature, the degree of freedom in designing physical properties by selecting side chains is high. The high heat-resistant resins described above do not have as many types of constituent monomers as acrylic resins and methacrylic resins, and the design range of characteristics and physical properties is narrow. Also from this point, acrylic resins and methacrylic resins are superior to other heat resistant resins.

Furthermore, acrylic resins and methacrylic resins have high oxidation resistance and reduction resistance that do not decompose even in high energy density power storage devices such as lithium ion secondary batteries. Adhesives and binders used in power storage devices Suitable as resin.

[Characteristics of heat-resistant resin of the present invention]
Resins for power storage devices are required to have oxidation resistance and reduction resistance. However, there are not many materials that satisfy these requirements, and limited resins such as fluorine resins such as PTFE and PVDF have been mainly used.

Therefore, the inventors examined the oxidation resistance and reduction resistance of various resin materials, and when many of acrylic acid, acrylic acid ester, methacrylic acid, and methacrylic acid ester polymers are used in power storage devices. It was discovered that the required oxidation resistance and reduction resistance were satisfied.

That is, as a resin material having oxidation resistance and reduction resistance constituting the heat resistant resin of the present invention, first, acrylic acid, acrylic acid ester, methacrylic acid, a homopolymer of methacrylic acid ester, a copolymer thereof or the like Use a mixture. A monomer (constituent monomer) that can be used to obtain a homopolymer, a copolymer, or a mixture thereof is defined by the values of HOMO (Highest Occupied Molecular Orbital) and LUMO (Lowest Unoccupied Molecular Orbital).

The heat-resistant resin of the present invention is intended for use in power storage devices such as lithium ion secondary batteries, electric double layer capacitors, lithium ion capacitors, sulfide solid state batteries, oxide solid state batteries, and thin film batteries. . In selecting a resin material that can be used in these power storage devices, the values of HOMO and LUMO are used as indicators of oxidation resistance and reduction resistance.

Table 1, Table 2A, Table 2B, Table 3A, Table 3B show HOMO values and LUMO values obtained by calculation for various resin materials.

Table 1 shows HOMO values and LUMO values of polyolefin resin, CMC (carboxymethylcellulose), PVDF (polyvinylidene fluoride), acrylic acid ester, and methacrylic acid ester.

Tables 2A and 2B show HOMO values and LUMO values of acrylic acid, acrylic acid ester and acrylamide, and Tables 3A and 3B show HOMO values of methacrylic acid, methacrylic acid ester and methacrylamide. , Shows the LUMO value. The side chains shown in Table 2A, Table 2B, Table 3A, and Table 3B correspond to the portion of —O—R ₁ shown in Formula (1). That is, the chemical species bonded to the carbonyl group of the chemical formula represented by formula (1) was defined as a side chain.

Note that the quantum chemistry calculation program Gaussian 03 was used to obtain the HOMO value and the LUMO value. First, the molecular structure was optimized to determine the stable structure of the molecule. Thereafter, the energy levels of HOMO and LUMO were calculated using the stable structure. The conditions in each calculation are as follows.
In the structural optimization calculation, B3LYP method was used, and 3-21G ^* was used as the basis function of atomic orbitals.
In addition, the Hartree-Fock method was used to calculate the energy levels of HOMO and LUMO, and 6-311G was used as the basis function of atomic orbitals.

In general, monomers such as acrylic acid, acrylic acid ester, methacrylic acid, and methacrylic acid ester are used for separators of lithium ion batteries, and polyolefin-based polymer resins that are known not to be decomposed even in contact with the positive electrode Compared with (polyethylene, polypropylene), it has lower or equivalent HOMO (the smaller the value of HOMO, the less it is oxidized) (see Table 1, Table 2A, 2B, Table 3A, 3B). Also, LUMO has a higher value than CMC (carboxymethylcellulose) and PVDF (polyvinylidene fluoride) widely used for a binder of a negative electrode layer of a lithium ion battery (the larger the LUMO value, the more difficult it is reduced). (See Table 1, Tables 2A and 2B, Tables 3A and 3B).

The polymer and copolymer used in the heat-resistant resin of the present invention are those obtained by polymerization or copolymerization of monomers having the above HOMO and LUMO values. The polymer also has the same oxidation resistance and reduction resistance as the monomer.

However, in the heat resistant resin of the present invention, it is not always necessary to define both HOMO and LUMO of the constituent monomers.
For example, when the member using the heat-resistant resin of the present invention is a separator or an electrolyte part, since they are disposed between and in contact with the positive electrode and the negative electrode, both oxidation resistance and reduction resistance are provided. I need it.

On the other hand, when used as a positive electrode binder, since it is exposed to an oxidizing atmosphere, it is necessary to define HOMO as an index of oxidation resistance, but it is not exposed to a reducing atmosphere, so it is necessary to specify LUMO. There is no.

Conversely, when used as a negative electrode binder, since it is exposed to a reducing atmosphere, it is necessary to define LUMO as an index of reduction resistance, but since it is not exposed to an oxidizing atmosphere, HOMO is specified. do not have to.

Also, when using as an adhesive, it is necessary to select whether or not HOMO and LUMO are prescribed depending on which part is arranged.

It is desirable that the resin used in the electricity storage device has a HOMO of −8.40 eV or less and a LUMO of 2.70 eV or more. This value is based on polyacrylamide. Polyacrylamide is used in power storage devices with relatively low energy density, for example, by adding it to the electrolyte of lead acid batteries or manganese dry batteries. Therefore, if it has a value of HOMO and LUMO comparable to those of polyacrylamide, it can be used as a resin for an electricity storage device having a relatively low energy density.

Furthermore, for use in lithium ion secondary batteries and electric double layer capacitors with higher energy density, it is desirable that HOMO is −10.71 eV or less and LUMO is 2.77 eV or more.

The values of HOMO and LUMO are determined based on the resin currently used in the lithium ion secondary battery. That is, the HOMO value was set to −10.71 eV or less in consideration of the HOMO of polypropylene, which is a general separator material, and the LUMO value was set to 2.77 eV or more in the positive electrode layer and the negative electrode layer. This is in consideration of the LUMO of PVDF, which is a binder material that can be used for any of these (see Tables 1, 2A, 2B, and 3A, 3B).

In this example, acrylic resin and methacrylic resin were prepared, and the thermal decomposition temperature was examined.

[1] Measurement of thermal decomposition temperature of homopolymer of acrylic ester and methacrylic ester Here, the thermal decomposition temperature of the following resin (polymer (homopolymer)) was measured by TG.
(1) polymethyl acrylate (PMA; Aldrich, molecular weight 40000),
(2) polymethyl methacrylate (PMMA; Nacalai, molecular weight 800000),
(3) Polyethyl methacrylate (PEMA; Aldrich, molecular weight 515000),
(4) Poly (n-butyl methacrylate) (PBMA; Aldrich, molecular weight 337000)
In the measurement, about 10 mg of each sufficiently dried resin (polymer) was measured and measured under the following measurement conditions.

<TG (thermogravimetric) measurement conditions>
Measuring device: Seiko Instruments TG / DTA 320
Temperature rise range: 25 ° C to 600 ° C
Temperature increase rate: 10 ° C / min
Atmosphere: Air atmosphere Air flow rate: 200mL / min
The results of the above TG measurement are shown in FIG.

As shown in FIG. 1, polymethyl acrylate (PMA) has heat resistance that does not decompose even at 260 ° C., but polymethyl methacrylate (PMMA), polyethyl methacrylate (PEMA), polymethacrylic acid having a methacrylic acid skeleton. It was confirmed that the decomposition of n-butyl (PBMA) started at 130 ° C.

In this TG measurement, the rate of temperature increase is 10 ° C./min. However, in the reflow process when reflow soldering the power storage device, the power storage device passes through a reflow furnace set to a predetermined temperature. Therefore, the time of exposure to high temperature is short, and the temperature rise and fall are also performed quickly. Therefore, when judging whether or not thermal decomposition has occurred using the weight loss rate under the above TG measurement conditions as an index, weight loss If the rate is up to about 2%, it is considered appropriate to judge that there is no problem of thermal decomposition. This is the same when the thermal decomposition resistance is evaluated from the results shown in FIGS.

[2] Thermal decomposition temperature measurement of copolymer of acrylic ester and methacrylic ester Using methyl acrylate and methyl methacrylate as constituent monomers, and mixing ratio (molar ratio) of methyl acrylate and methyl methacrylate,
Methyl acrylate: methyl methacrylate = 10: 0 (0%),
Methyl acrylate: methyl methacrylate = 9: 1 (10%),
Methyl acrylate: methyl methacrylate = 8: 2 (20%),
Methyl acrylate: methyl methacrylate = 7: 3 (30%),
Methyl acrylate: methyl methacrylate = 6: 4 (40%)
As a copolymer. And about the copolymer, TG measurement was performed and the thermal decomposition temperature was investigated.

The copolymer was synthesized as follows.
A 1-liter separable flask equipped with a nitrogen gas inlet tube, a reflux device, a thermometer, and a stirring function was charged with 198.5 g of methanol and 0.82 g of azobisisobutyronitrile and stirred, and nitrogen gas was bubbled. While warming to 63 ° C.
Then, 180 g of methyl acrylate and methyl methacrylate mixed in the above proportions were added dropwise to the flask over 2 hours using a dropping funnel.
After completion of the dropwise addition, 0.41 g of azobisisobutyronitrile and 7.6 g of methanol were added and heated for 2 hours, then heated to 65 ° C. and heated for 2 hours to obtain a polymer solution (resin solution).
The produced polymer was dried overnight in an oven at 130 ° C. to remove the solvent.
After removing the solvent, TG measurement was performed in the same manner as described in [1] above, and the thermal decomposition temperature was measured.
The result of TG measurement is shown in FIG.

As shown in FIG. 2, the decomposition temperature tends to decrease as the proportion of methyl methacrylate increases, but the proportion of methyl methacrylate is 20% in terms of mol% (methyl acrylate: methyl methacrylate (molar ratio). ) = 8: 2), it was confirmed that no decomposition occurs at the reflow temperature (260 ° C.).

In this example, the ratio of methyl methacrylate, that is, the ratio of the monomer of the methacrylic acid skeleton in the total monomer is shown as 0%, 10%, and 20% in mol%. It has been confirmed that practical heat resistance can be obtained when the acid-based ratio is less than 30% (methyl acrylate: methyl methacrylate (molar ratio) = 5: 5).

[3] Measurement of thermal decomposition temperature of resins with different side chain structures Constituent monomers include methyl acrylate (an acrylate ester in which the first carbon of R ₁ is primary) and cyclohexyl acrylate (the first carbon of R ₁ Acrylic acid ester, which is secondary, was used for copolymerization at various ratios. Then, the thermal decomposition temperature was measured by performing TG measurement.

The copolymer was synthesized as follows.
A 1-liter separable flask equipped with a nitrogen gas inlet tube, a reflux device, a thermometer, and a stirring function was charged with 198.5 g of methanol and 0.82 g of azobisisobutyronitrile and stirred while continuously bubbling nitrogen gas. Warmed to 63 ° C.
Then, 180 g of methyl acrylate and cyclohexyl acrylate mixed at the following ratios were added dropwise to the flask with a dropping funnel over 2 hours.
After completion of the dropwise addition, 0.41 g of azobisisobutyronitrile and 7.6 g of methanol were added and heated for 2 hours, then heated to 65 ° C. and heated for 2 hours to obtain a polymer solution (resin solution).

In addition, the mixing ratio of said methyl acrylate and cyclohexyl acrylate is a molar ratio, respectively.
Methyl acrylate: cyclohexyl acrylate = 10: 0 (0%),
Methyl acrylate: cyclohexyl acrylate = 9: 1 (10%),
Methyl acrylate: cyclohexyl acrylate = 8: 2 (20%),
Methyl acrylate: cyclohexyl acrylate = 7: 3 (30%),
Methyl acrylate: cyclohexyl acrylate = 6: 4 (40%),
Methyl acrylate: cyclohexyl acrylate = 5: 5 (50%)
It was.

The produced polymer was dried overnight in an oven at 130 ° C. to remove the solvent.
After removing the solvent, TG measurement was performed in the same manner as described in [1] above, and the thermal decomposition temperature was measured.
The result of TG measurement is shown in FIG.

As shown in FIG. 3, it can be seen that a homopolymer of methyl acrylate (an acrylate ester in which the carbon at the 1-position of R ₁ is primary) not blended with cyclohexyl acrylate does not thermally decompose at 260 ° C.

In addition, in the case of a copolymer of methyl acrylate and cyclohexyl acrylate (acrylate ester in which the carbon at the 1-position of R ₁ is secondary), within the above blending ratio range, in both cases, It was confirmed that no thermal decomposition occurred.

In addition, not only the combination shown above,
(a) a copolymer of methyl acrylate (an acrylate ester in which the first carbon of R ₁ is primary) and ethyl acrylate (an acrylate ester in which the first carbon of R ₁ is primary);
(b) Copolymer of methyl acrylate (acrylic ester in which the first carbon of R ₁ is primary) and 2-ethylhexyl acrylate (acrylic ester in which the first carbon of R ₁ is primary) ,
(c) a copolymer of methyl acrylate (acrylic ester in which the first carbon of R ₁ is primary) and isopropyl acrylate (acrylic ester in which the first carbon of R ₁ is secondary), etc. In some cases, the same tendency has been confirmed.

However, in the case of a copolymer of methyl acrylate (acrylate ester in which the 1st carbon of R ₁ is primary) and t-butyl acrylate (acrylate ester in which the 1st carbon of R ₁ is tertiary) It has been confirmed that the thermal decomposition temperature is greatly reduced and decomposes at 260 ° C.

based on the above results,
(a) R ₁ represented by the chemical formula (1) has at least one carbon, R ₁ is bonded to the ester bond represented by the chemical formula (1) by the carbon, and the carbon at the 1-position of R ₁ is primary. Or satisfying the requirement that acrylic acid ester that is secondary or acrylic acid in which R ₁ represented by chemical formula (1) is hydrogen is used as a constituent monomer,
(b) a copolymer having at least one of acrylic acid ester and acrylic acid and at least one of methacrylic acid ester and methacrylic acid as a constituent monomer, wherein the constituent monomer has R ₁ represented by chemical formula (1) It has at least one carbon, and R ₁ is bonded to the ester bond represented by the chemical formula (1) by the carbon, and the carbon at the 1-position of R ₁ is primary or secondary, or the chemical formula (1) When reflow soldering is performed by satisfying the requirement that the R ₁ shown is acrylic acid or methacrylic acid in which hydrogen is present, and the sum of mol% of methacrylic acid ester and methacrylic acid constituting the copolymer is 30% or less It can be seen that a heat-resistant resin material excellent in heat resistance that hardly undergoes thermal decomposition even at a temperature of 260 ° C. can be obtained.

In Example 2, in order to evaluate the heat-resistant resin of the present invention, a separator (ceramic separator) using a polyacrylic acid ester (polymethyl acrylate) having a heat-resistant composition having the requirements of the present invention as a binder resin. And an electric double layer capacitor (cell) having an insulating adhesive layer using a copolymer of methyl acrylate and ethyl acrylate as a binder resin, and the obtained electric double layer capacitor (cell) It was passed through a reflow furnace and the electrical characteristics before and after that were investigated.

[1] Preparation of positive electrode layer (negative electrode layer) current collector layer First, an aluminum foil having a thickness of 20 μm was prepared as a current collector (active material current collector layer) for the positive electrode layer and the negative electrode layer.

[2] Preparation of slurry for active material layer Activated carbon (BET specific surface area 1668 m ² / g, average pore diameter 1.83 nm, average particle diameter (D ₅₀ ) 1.26 μm) 29.0 g, carbon black (Tokai Carbon Co., Ltd.) “Toka Black # 3855”, 2.7 g of BET specific surface area of 90 m ^{2 /} g) was weighed and put into a 1000 ml pot, and PSZ grinding media with a diameter of 2.0 mm and 286 g of deionized water were added. After the addition, the mixture was dispersed by mixing at 150 rpm for 4 hours using a rolling ball mill.
Then, 3.0 g of carboxymethylcellulose (“CMC2260” manufactured by Daicel Chemical Industries, Ltd.) and 2.0 g of an aqueous polyacrylate resin solution of 38.8% by weight are added to the pot and further mixed for 2 hours. A slurry was prepared.

[3] Coating of slurry for active material layer Using a # 500 mesh screen printing plate with a plate thickness of 5 μm, as shown in FIGS. 4 (a) and 4 (b), an active material current collector layer (positive electrode current collector) The active material layer slurry produced by the above method is screen-printed on the layer 111 (negative electrode current collector layer 121) and dried at 100 ° C. for 30 minutes, and the positive electrode active material layer 112 (6 μm thick) ( A negative electrode active material layer 122) was formed.

[4] Preparation of separator layer slurry (1) Synthesis of polymer (heat-resistant resin) used for separator layer binder A 1-liter separable flask equipped with a nitrogen gas inlet tube, a reflux device, a thermometer, and a stirring function 198.5 g of methanol and 0.82 g of azobisisobutyronitrile were charged and stirred, and heated to 63 ° C. while bubbling nitrogen gas.

Then, 180 g of methyl acrylate was dropped into the flask with a dropping funnel over 2 hours. After completion of dropping, 0.41 g of azobisisobutyronitrile and 7.6 g of methanol were added and heated for 2 hours, and then heated to 65 ° C. and heated for 2 hours to obtain a polymer (methyl polyacrylate) solution. .

(2) Preparation of separator layer binder After adding 2.5 times the weight of NMP to the weight of the polymer contained in the polymer solution, evaporation was performed while heating to 50 ° C. The solvent (methanol) in the combined solution was removed to obtain a 40 wt% NMP solution of polymethyl acrylate.

(3) Preparation of separator layer slurry 100 g of spherical alumina powder (manufactured by Denki Kagaku Kogyo Co., Ltd., average particle size (D50) 0.3 μm) and 80 g of NMP as a solvent were charged into a 500 ml pot. Furthermore, PSZ grinding media having a diameter of 5 mm were placed, and the mixture was dispersed by mixing at 150 rpm for 16 hours using a rolling ball mill.

Thereafter, the synthesized polymethyl acrylate binder solution (40 wt% NMP solution) was put into the pot and mixed at 150 rpm for 4 hours using a rolling ball mill to prepare a separator layer slurry of 80% PVC.

In addition, pigment volume concentration PVC (Pigment Volume Concentration) is a value calculated | required by following formula (1).
PVC = (volume of inorganic fine particles) / (volume of inorganic fine particles + volume of binder resin) × 100 (1)
However,
Volume of inorganic fine particles = weight of inorganic fine particles / density of inorganic fine particles Volume of binder resin = weight of binder resin / density of binder resin

[5] Coating of slurry for separator layer Using a # 500 mesh screen printing plate having a plate thickness of 5 μm, the slurry for separator layer prepared by the above method was used as shown in FIGS. 5 (a) and 5 (b). The separator layer 113 (123) having a thickness of 3 μm was formed by coating on the positive electrode active material layer 121 (negative electrode active material layer 122) and drying at 120 ° C. for 30 minutes.

[6] Preparation of slurry for insulating adhesive layer (1) Synthesis of polymer (heat-resistant resin) used for binder for insulating adhesive layer 1 liter equipped with nitrogen gas inlet tube, reflux device, thermometer, stirring function A separable flask was charged with 198.5 g of methanol and 0.82 g of azobisisobutyronitrile and stirred, and heated to 63 ° C. while bubbling nitrogen gas.

Then, a mixed solution of 144 g of methyl acrylate and 36 g of ethyl acrylate was dropped into the flask with a dropping funnel over 2 hours. After completion of dropping, 0.41 g of azobisisobutyronitrile and 7.6 g of methanol were added and heated for 2 hours, and then heated to 65 ° C. and heated for 2 hours to obtain a polymer (copolymer) solution.

(2) Adjustment of insulating adhesive layer binder After adding 2.5 times the weight of NMP to the weight of the polymer contained in the polymer solution, evaporation was performed while heating to 50 ° C. Then, methanol as a solvent in the polymer solution was removed to obtain a 40 wt% NMP solution of a copolymer of methyl acrylate and ethyl acrylate.

(3) Preparation of Slurry for Insulating Adhesive Layer 100 g of spherical alumina powder (manufactured by Denki Kagaku Kogyo Co., Ltd., average particle size (D50) 0.3 μm) and 80 g of NMP as a solvent were charged into a 500 ml pot. Furthermore, PSZ grinding media having a diameter of 5 mm were placed, and the mixture was dispersed by mixing at 150 rpm for 16 hours using a rolling ball mill.
Thereafter, a binder solution of a copolymer of methyl acrylate and ethyl acrylate (40 wt% NMP solution) was put into the pot and mixed for 4 hours at 150 rpm using a rolling ball mill, and an insulating property of PVC 40% An adhesive layer slurry was prepared.

[7] Coating of insulating adhesive layer slurry Using a # 500 mesh screen printing plate with a plate thickness of 5 μm, the insulating adhesive layer slurry prepared by the above method is shown in FIGS. 6 (a) and 6 (b). As shown in the figure, coating is performed on the positive electrode current collector layer 111 (negative electrode current collector layer 121) in the region surrounding the separator layer 113 (123), followed by drying at 120 ° C. for 30 minutes. An insulating adhesive layer 114 (124) having a thickness of 3 μm was formed in the surrounding region.

[8] Punching of printed body A printed body on which an active material slurry, a separator layer slurry, and an insulating adhesive layer slurry are printed on the active material current collector layer produced in [7] above is used as a mold Thomson blade. Using a hand press, as shown in FIGS. 7A, 7B, 7C, 7D, and 7E, the positive electrode layer 115 and the negative electrode layer 125 were manufactured by punching into a predetermined shape.
In this punching process, protrusions 111a and 121a functioning as connection terminals are formed on the divided positive electrode current collector 111 and negative electrode current collector 121, which constitute the positive electrode layer 115 and the negative electrode layer 125. I am punching so that.

As shown in FIGS. 7B and 7C, the positive electrode layer 115 includes a positive electrode current collector layer 111, a positive electrode active material layer 112 formed on the surface thereof, a separator layer 113, and an insulating adhesive layer 114. And.
Further, as shown in FIGS. 7D and 7E, the negative electrode layer 125 includes a negative electrode current collector layer 121, a negative electrode active material layer 122 formed on the surface thereof, a separator layer 123, and an insulating adhesive. Layer 124.

[9] Production of Laminate The surface of the positive electrode layer 115 and the negative electrode layer 125 produced in [8] above, on which various slurries are applied in the posture shown in FIGS. 8 (a) and 8 (b). Were arranged so as to face each other, and the end portion was fixed with an adhesive tape (not shown), to produce a laminate 106.
In Example 1, as shown in FIGS. 8 (a) and 8 (b), an Al tab is drawn into the protrusions 111a and 121a of the positive electrode current collector 111 and the negative electrode current collector 121 shown in FIG. The electrodes (electrode tabs) 116 and 126 are connected.
As described above, in Example 2, a laminated body (a pair of positive and negative electrode aggregate sheets) 106 in which the positive electrode layer 115 and the negative electrode layer 125 were insulated by the separator layer 123 and the insulating adhesive layer 124 was produced.

[10] Storing the laminated body in a package As shown in FIG. 9, a lid 70a and a base portion 70b on which a positive electrode package electrode 61 and a negative electrode package electrode 62 are formed so as to wrap around from both ends to the lower surface side are provided. A package 70 is prepared. Here, as the lid body 70a and the base portion 70b, those made of liquid crystal polymer are used.

Then, a conductive adhesive containing gold as conductive particles is applied to the positive electrode side and negative electrode side extraction electrodes (electrode tabs) 116 and 126 of the laminate 106 by dipping.

Then, the laminated body 106 is disposed inside the base portion 70b of the package 70 so that the applied conductive adhesive is connected to the positive electrode package electrode 61 and the negative electrode package electrode 62, and heated at 170 ° C. for 10 minutes. Thus, the conductive adhesive 108 was cured.

As described above, as shown in FIG. 9, the stacked body 106 is accommodated in the package 70, and the positive electrode side electrode tab 116 and the negative electrode side electrode tab 126 of the stacked body 106 are connected to the positive electrode package electrode via the conductive adhesive 108. The structure connected to 61 and the negative electrode package electrode 62 was obtained.

[11] Injection of electrolyte solution Then, the electrolyte solution 109 was injected into the package 70 and sealed. Here, EMITFSI (1-ethyl-3-methylimidazolium bistrifluoromethanesulfonylimide) is injected under reduced pressure as the electrolytic solution 109, a lid 70a is disposed on the upper surface of the base portion 70b of the package 70, and the package The base part 70b and the lid 70a were welded by irradiating laser along the frame part of the base part 70b of 70, and an electric double layer capacitor (cell) having a structure as shown in FIG. 9 was obtained.

[12] Measurement of characteristics before and after passing through the reflow furnace DC capacity was measured as the electrochemical characteristics of the electric double layer capacitor produced as described above. As a result, the DC capacity of the obtained electric double layer capacitor (electric double layer capacitor before passing through the reflow furnace) was 0.21 mF.
Next, the electric double layer capacitor was passed through a reflow furnace set at 260 ° C. And the direct-current capacity | capacitance was measured about the electric double layer capacitor after passing through a reflow furnace. As a result, the direct current capacity of the electric double layer capacitor after passing through the reflow furnace was 0.20 mF, and it was confirmed that no problematic deterioration occurred.
From this result, it is understood that a highly reliable electric double layer capacitor having excellent heat resistance can be produced by using a heat resistant resin having the requirements of the present invention.

In the above embodiment, the case where the separator of the electric double layer capacitor and the insulating adhesive layer are formed of the heat resistant resin of the present invention has been described as an example. However, the electricity storage device that can use the heat resistant resin of the present invention. Is not limited to electric double layer capacitors, but can also be applied to lithium ion secondary batteries, lithium ion capacitors, and the like.

That is, each of the lithium ion secondary battery and the lithium ion capacitor has a structure in which a positive electrode layer and a negative electrode layer are laminated via a separator layer or an insulating adhesive layer and are housed in an outer packaging material together with an electrolytic solution. There is something. And the material containing the heat resistant resin of this invention can be used for these separators and an insulating contact bonding layer.
In addition, as a lithium ion secondary battery or a lithium ion capacitor, the thing of the following structures is illustrated, for example.

<Lithium ion secondary battery>
In a lithium ion secondary battery, for example, an aluminum foil is used as a positive electrode current collector layer, and an electrode in which a mixture layer containing a lithium composite oxide is provided on the aluminum foil as a positive electrode active material layer is used as a positive electrode layer.
In addition, as the negative electrode current collector layer, for example, a copper foil is used, and an electrode in which a mixture layer containing graphite is provided as a negative electrode active material layer on the copper foil is used as the negative electrode layer.
Then, the positive electrode layer and the negative electrode layer are laminated via a separator and an insulating adhesive layer using the heat-resistant resin of the present invention as in the above-described example, and a laminate is formed, for example. A lithium ion secondary battery can be obtained by using 1 mol / l LiBF ₄ dissolved in a mixed solvent of ethylene carbonate and diethyl carbonate as an electrolytic solution (nonaqueous electrolytic solution).

<Lithium ion capacitor>
In the lithium ion capacitor, for example, an aluminum foil is used as the positive electrode current collector layer, and an electrode in which a mixture layer containing activated carbon is provided as a positive electrode active material layer on the aluminum foil is used as the positive electrode layer.
Further, as the negative electrode current collector layer, for example, a copper foil is used, and an electrode provided with a mixture layer containing graphite as a negative electrode active material layer on the copper foil is used as a negative electrode layer, and lithium ions are further pre-doped into the negative electrode layer. To do.
Then, the positive electrode layer and the negative electrode layer are laminated via a separator and an insulating adhesive layer using the heat-resistant resin of the present invention as in the above-described example, and a laminate is formed, for example. A lithium ion capacitor can be obtained by using, as an electrolytic solution (nonaqueous electrolytic solution), 1 mol / l LiBF ₄ dissolved in a mixed solvent of ethylene carbonate and diethyl carbonate.
Furthermore, the heat resistant resin of the present invention can also be used for sulfide solid state batteries, oxide solid state batteries, thin film batteries and the like.

The present invention is not limited to the above-described embodiments and examples, and the types and combinations of constituent monomers constituting the heat-resistant resin, the blending ratio, the types and blending ratios of the inorganic fine particles, the configuration of the positive electrode layer and the negative electrode layer Various applications within the scope of the invention regarding materials, forming methods, specific configurations of power storage elements (such as positive electrode layers, negative electrode layers, separators, insulating adhesive layers and the number of layers), types of electrolytes, etc. It is possible to add deformation.

61 Positive Package Electrode 62 Negative Electrode Package Electrode 70 Package 70a Lid 70b Base Part 106 Laminate 108 Conductive Adhesive 109 Electrolyte 111 (121) Active Material Current Collector Layer
112 Positive electrode active material layer 113 (123) Separator layer 114 (124) Insulating adhesive layer 115 Positive electrode layer 116 (126) Lead electrode (electrode tab)
122 Negative electrode active material layer 125 Negative electrode layer A Electric double layer capacitor

Claims (20)

1. A heat resistant resin comprising at least one of the following (a) and (b) as a main component.
   (a) R ₁ represented by the chemical formula (1) has at least one carbon, R ₁ is bonded to the ester bond represented by the chemical formula (1) by the carbon, and the carbon bonded to the ester bond is 1 A homopolymer or a copolymer having acrylic acid ester which is secondary or secondary, or acrylic acid in which R ₁ is hydrogen represented by chemical formula (1) as a constituent monomer (b) at least one of acrylic acid ester and acrylic acid A copolymer having at least one of a seed and a methacrylic acid ester and methacrylic acid as a constituent monomer, wherein R ₁ in the chemical formula (1) has at least one carbon, and R ₁ has the chemical formula Acrylic ester, methacrylic ester, chemical, which is bonded to the ester bond shown in (1) by the carbon, and the carbon bonded to the ester bond is primary or secondary. Acrylic acid wherein R ₁ is hydrogen as shown in (1), a methacrylic acid, a copolymer mol% of the sum of methacrylic acid esters and methacrylic acid constituting the copolymer is not more than 30%
   

   

   [In the formula (1), R is H or CH ₃ : R ₁ is H or a chemical species having at least one carbon]
2. The heat resistant resin according to claim 1,
   At least one homopolymer included in the group of homopolymers defined in (a),
   At least one copolymer included in the group of copolymers defined in (a) above,
   A heat-resistant resin, which is a mixture of at least two selected from the group consisting of at least one copolymer included in the group of copolymers defined in (b).
3. The heat-resistant resin according to claim 1 or 2, wherein the thermal decomposition temperature is higher than 260 ° C.
4. The heat resistant resin according to any one of claims 1 to 3, wherein the constituent monomer has a HOMO of -8.40 eV or less.
5. The heat-resistant resin according to any one of claims 1 to 3, wherein the constituent monomer has a HOMO of -10.71 eV or less.
6. The heat resistant resin according to any one of claims 1 to 3, wherein the constituent monomer has a LUMO of 2.70 eV or more.
7. The heat-resistant resin according to any one of claims 1 to 3, wherein the constituent monomer has a LUMO of 2.77 eV or more.
8. The heat resistant resin according to any one of claims 1 to 3, wherein the constituent monomers have a HOMO of -8.40 eV or less and a LUMO of 2.70 eV or more.
9. The heat-resistant resin according to any one of claims 1 to 3, wherein the constituent monomers have a HOMO of -10.71 eV or less and a LUMO of 2.77 eV or more.
10. The heat resistant resin according to any one of claims 1 to 9, wherein inorganic fine particles are blended.
11. 11. The heat-resistant resin according to claim 1, which is used for an electricity storage device.
12. The heat-resistant resin according to any one of claims 1 to 10, wherein the heat-resistant resin is used for an electricity storage device that supports mounting by reflow soldering.
13. 12. The power storage device is one selected from the group consisting of a lithium ion secondary battery, a lithium ion capacitor, an electric double layer capacitor, a sulfide solid state battery, an oxide solid state battery, and a thin film battery. Or the heat resistant resin of 12.
14. An adhesive used for manufacturing an electricity storage device, characterized by using the heat-resistant resin according to any one of claims 1 to 10.
15. The positive electrode layer and the negative electrode layer are laminated so as to face each other via an insulating adhesive layer in a predetermined region, and are laminated so as to face each other via a separator in the other predetermined region, and the positive electrode layer and An insulating adhesive layer used in an electricity storage device having a structure in which the negative electrode layer is bonded via the insulating adhesive layer;
    An insulating adhesive layer produced using the heat-resistant resin according to claim 8 or 9.
16. A positive electrode layer and a negative electrode layer are separators for use in an electricity storage device including a laminate having a structure in which the separators are laminated via a separator,
    A separator produced using the heat-resistant resin according to claim 8 or 9.
17. A solid electrolyte comprising a powdered electrolyte and the heat resistant resin according to claim 8 or 9.
18. The positive electrode layer and the negative electrode layer are laminated so as to face each other via an insulating adhesive layer in a predetermined region, and are laminated so as to face each other via a separator in the other predetermined region, and the positive electrode layer and An electricity storage device having a structure in which the negative electrode layer is bonded via the insulating adhesive layer,
    An electrical storage device comprising the insulating adhesive layer according to claim 15 as the insulating adhesive layer.
19. A power storage device comprising a laminate having a structure in which a positive electrode layer and a negative electrode layer are laminated via a separator, and the positive electrode layer and the negative electrode layer in contact with the separator are directly bonded to the separator. ,
    An electricity storage device comprising the separator according to claim 16 as the separator.
20. The electricity storage device according to claim 18 or 19, wherein the electricity storage device is one selected from the group consisting of a lithium ion secondary battery, a lithium ion capacitor, and an electric double layer capacitor.

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