JP2019160409A - Separator for electrochemical element - Google Patents

Abstract

To provide a separator achieving both low resistance and durability in an electrochemical element.SOLUTION: A separator for an electrochemical element is a separator used in an electrochemical element. The separator includes: a porous support; and a resin composition impregnated layer including a resin composition impregnated into the porous support, the resin composition containing a polymer and an inorganic compound. The separator is characterized in that an average position of a surface of a resin composition impregnated layer based on a porous support surface relative to the thickness of the porous support, the average position being measured by a predetermined method on each of both surfaces of the separator, is in a range of -10% or more and +30% or less.SELECTED DRAWING: Figure 1

Description

The present invention relates to a separator for an electrochemical element. More specifically, the present invention relates to a separator used for electrochemical elements such as batteries, capacitors, capacitors, sensors, fuel cells, and electrolyzers.

In recent years, the importance of batteries has increased rapidly in many industries, from small portable devices to large-scale applications such as automobiles. New battery systems that have advantages mainly in terms of capacity, energy density, and secondary battery use. Have been developed. Also, various electrochemical elements other than batteries have been developed that have advantages in each aspect.

For example, various developments and improvements have been made for separators used in batteries. For example, separators using a porous sheet have been disclosed (for example, see Patent Documents 1 to 5). Also disclosed is an electrochemical element having a different type of separator, in which the porous substrate of the separator prevents a short circuit between the cathode and the anode due to thermal shrinkage and prevents explosion and ignition of the electrochemical element due to overcharging. (For example, see Patent Document 6).

JP 2000-208122 A JP 2012-1224029 A JP 2013-206846 A JP 2014-3038 A International Publication No. 2016/093146 JP 2014-239041 A

As described above, a separator having a porous sheet such as a nonwoven fabric as a core material is disclosed, and such a separator is excellent in strength, but there is a high need for further performance improvement of the separator in an electrochemical device. It has been desired to achieve both low resistance and durability.

This invention is made | formed in view of the said present condition, and it aims at providing the separator which was compatible with the low resistance and durability in an electrochemical element.

The present inventors have made various studies on separators that achieve both low resistance and durability in electrochemical devices, and the porous support and the resin composition containing a polymer and an inorganic compound are impregnated in the porous support. Focusing on the separator having the resin composition-impregnated layer, a separator was prepared by adjusting the position of the surface of the resin composition-impregnated layer with respect to the surface of the porous support on the both surfaces of the separator within a predetermined range. The present inventors have found that this separator is remarkably excellent in durability while sufficiently maintaining the low resistance required for an electrochemical element, and conceived that the above problems can be solved brilliantly. The invention has been reached.

That is, the present invention is a separator used for an electrochemical device, and the separator is a porous support, and a resin composition-impregnated layer in which the porous support is impregnated with a resin composition containing a polymer and an inorganic compound. And the average position of the resin composition-impregnated layer surface with respect to the thickness of the porous support relative to the thickness of the porous support measured on each of both surfaces of the separator is −10% or more, +30 % Separator for electrochemical elements, characterized in that it is in the range of% or less.
Method for measuring average position of resin composition-impregnated layer surface based on porous support surface relative to thickness of porous support:
(1) In a cross section obtained by cutting perpendicularly to the surface of the separator, any five regions each having a length in the width direction of 80 μm are selected using a scanning electron microscope.
(2) For each region, a porous support in a region on the left side of the center point in the width direction on one surface side of the separator on an enlarged photograph of one surface portion of the separator, taken using a scanning electron microscope A straight line having a length in the width direction between both end portions of 60 μm or more is defined as a reference line A.
(3) When a line parallel to the reference line A is scanned from the side opposite to the one surface side of the separator to the one surface side of the separator on the enlarged photograph of (2), the length of the parallel line A filling line B is defined as a boundary line where a filling portion in which the total length of the space portions on the parallel line is 10% or less is terminated.
(4) A distance X between the reference line A and the filling line B is calculated. When the filling line B is in front of the reference line A in the scanning direction of the parallel lines, the position of the resin composition impregnated layer surface with respect to the surface of the porous support is -X, and when the reference line A is exceeded + X.
(5) For each region, even in an enlarged photograph of the surface portion opposite to the one surface of the separator, taken using a scanning electron microscope, the reference line A ′ is the same as in (2) to (4). The filling line B ′ is obtained, the distance X ′ between the reference line A ′ and the filling line B ′ is calculated, and the position + X ′ or −X ′ of the resin composition-impregnated layer surface with respect to the porous support surface is determined. Decide.
(6) For each region, the distance between the reference line A and the reference line A ′ in the enlarged photograph that can be observed with one field of view in the thickness direction of the separator taken with a scanning electron microscope is the thickness of the porous support. Let t.
(7) For each region, the ratio Y of the position + X or -X of the resin composition-impregnated layer surface with respect to the porous support surface relative to the thickness t of the porous support, and the thickness t of the porous support The ratio Y ′ of the position + X ′ or −X ′ of the resin composition impregnated layer surface with respect to the surface of the porous support is determined, and the average value of the ratio Y and the average value of the ratio Y ′ are respectively determined. The average position of the surface of the resin composition-impregnated layer based on the porous support surface relative to the thickness of the porous support on the surface.
The present invention is described in detail below.
A combination of two or more preferred embodiments of the present invention described below is also a preferred embodiment of the present invention.

The separator for an electrochemical element of the present invention has the above-described configuration, and is excellent in durability while sufficiently maintaining the low resistance in the electrochemical element.

It is a 1500 times enlarged photograph which image | photographed the cross section of the separator for electrochemical elements of this invention using the scanning electron microscope. It is a 1500 times enlarged photograph which image | photographed the cross section of the separator for electrochemical elements of the comparative example 1 using the scanning electron microscope. It is a 400 times enlarged photograph which image | photographed the cross section of the separator for electrochemical elements of this invention using the scanning electron microscope.

<Electrochemical element separator>
The separator for electrochemical devices of the present invention has a porous support and a resin composition-impregnated layer impregnated with a resin composition containing a polymer and an inorganic compound on the porous support, The average position of the resin composition-impregnated layer surface based on the porous support surface relative to the thickness of the porous support measured by the above method is in the range of −10% or more and + 30% or less.
As a result, the resin composition-impregnated layer is appropriately filled up to the vicinity of the interface of the porous support on both surfaces of the separator, and the porous support not impregnated with resin while sufficiently reducing the resistance. The part which consists only of a body can be decreased, and durability can be made extremely outstanding.
In addition, when the electrochemical element is a battery, the battery can have a long life by the separator. For example, when the battery includes an electrode (for example, a zinc negative electrode) that undergoes a change in shape with charge and discharge, the electrochemical device separator of the present invention is likely to proceed with dendrite consisting only of a porous support. Since the proportion of the portion is small, the effect of suppressing a short circuit due to dendrite can be remarkably exhibited.

Regarding (1) above, when any five regions are selected using a scanning electron microscope in a cross section obtained by cutting perpendicularly to the surface of the separator, different regions having a width of 80 μm from one cross section May be selected, or a total of five regions having a width of 80 μm may be selected from 2 to 5 cross sections. For example, in the center of the coating width when the resin composition is applied to the release substrate, any three regions in the cross section in the flow direction of the resin composition, any two in the cross section in the direction orthogonal to the flow direction A region can be selected.

Regarding (2) above, the enlarged photograph is a region having a length of 80 μm in the width direction, and may be a photograph in which one surface portion of the separator is enlarged, and both ends in the thickness direction of the separator can be observed in one field of view. It doesn't have to be a thing. An arbitrary end portion of the porous support in the region on the left side from the midpoint in the width direction is connected to an arbitrary end portion of the porous support in the region on the right side from the midpoint in the width direction. A straight line having a length of 60 μm or more can be used as the reference line A. Among them, among the ends of the porous support in the region on the left side of the middle point in the width direction, the point closest to the separator surface The straight line connecting the point closest to the separator surface among the ends of the porous support in the region on the right side of the midpoint is preferably used as the reference line A. When the separator surface is made of a resin composition, the point closest to the separator surface is the end point of the porous support portion closest to the surface, and the separator surface is porous support. In the case of being composed of a body part, the end of the porous support part constituting the separator surface is the closest point to the separator surface (the distance from the separator surface is 0). It can be an arbitrary point at the end of the porous support portion to be constituted.

With respect to the above (3), the space portion on the parallel line means that there is no material constituting the separator for an electrochemical element of the present invention, such as a porous support or a resin composition, on the parallel line at one point during parallel line scanning. The space part (gap part) is said. The space portion is a black portion in FIGS. 1 and 2 showing an enlarged photograph of a cross section of the separator for an electrochemical element using a scanning electron microscope (SEM). In addition, the part with the material which comprises the separator for electrochemical elements of this invention, such as a porous support body and a resin composition, is the light color part thru | or white part of FIG. The length of the space portion on the parallel line can be measured by observing the cross section of the separator for an electrochemical element of the present invention using a scanning electron microscope (SEM) according to the method described in the examples.
Moreover, the sum total of the length of the space part on a parallel line means adding up the length of these space parts, when there are two or more space parts on a parallel line intermittently. Note that the length of the parallel lines is the length of the entire parallel lines within the range indicated by the captured image.
In the enlarged photograph, only one of the above-mentioned filling parts may be present, or two or more may be present. If there are two or more filling parts, there will be two or more boundary lines where the filling part ends correspondingly. In this case, the filling line B is the boundary line where the filling part ends. , And the line closest to the reference line A.

Regarding (4) above, the distance X between the reference line A and the filling line B is the distance between two straight lines that are parallel to each other, and is also referred to as the X value in this specification. The reference line A corresponds to the porous support surface, and the filling line B corresponds to the position of the resin composition impregnated layer surface. In this specification, the position of the resin composition-impregnated layer surface is defined as a relative position with respect to the porous support surface, and the filling line B is in front of the reference line A in the parallel line scanning direction. When it is -X, when it exceeds the reference line A, it is + X.
Although the magnification of the enlarged photograph when determining the reference line A and the filling line B and measuring the X value can be selected as appropriate, it is preferably 1000 times or more, more preferably 1500 times or more. The magnification is preferably 5000 times or less.

In the above (5), the surface opposite to the surface of the porous support / resin composition impregnated layer measured in (2) to (4) is the same as the method for obtaining the reference line A in (2) above. The reference line A ′ is obtained, and the filling line B ′ is obtained in the same manner as the method for obtaining the filling line B in (3) above, the distance X ′ between the reference line A ′ and the filling line B ′ is calculated, and the porous support is obtained. The position + X ′ or −X ′ of the resin composition-impregnated layer surface with respect to the body surface is determined.

Regarding (6) above, an enlarged photograph in which both ends in the thickness direction of the separator can be observed with one field of view is an enlarged photograph taken so that both ends in the thickness direction of the separator can be accommodated in a single photograph so that the thickness of the separator can be measured. It is a photograph, and usually has a lower magnification than the magnified photographs (2) to (4) and the magnified photograph (5).
The magnification of the enlarged photograph used for the measurement of the thickness of the porous support may be appropriately selected depending on the thickness, but is preferably 1000 times or less, more preferably 800 times or less. The magnification is preferably 400 times or more.
The thickness of the porous support is the distance t between the reference line A and the reference line A ′ as described above. Here, when the reference line A and the reference line A ′ are not parallel, the distance t is the shortest distance between both reference lines in the region having a width of 80 μm.

For the above (7), the average value of the ratio Y of the position + X or −X of the resin composition impregnated layer surface relative to the porous support surface relative to the thickness t of the porous support for each region, The average value of the ratio Y ′ of the position + X ′ or −X ′ of the resin composition-impregnated layer surface with respect to the surface t of the porous support relative to the thickness t of the porous support is within the range according to the present invention. Thus, as described above, the resin composition-impregnated layer is appropriately filled up to the vicinity of the interface of the porous support on both surfaces of the separator, and the effects of the present invention can be exhibited. The ratios Y and Y ′ are also referred to as the position of the resin composition-impregnated layer surface with respect to the thickness of the porous support relative to the thickness of the porous support in this specification, or the filling rate. It is calculated.
Y (%) = (position of resin composition impregnated layer surface with reference to porous support surface + X or −X / thickness t of porous support) × 100
Y ′ (%) = (position of the resin composition-impregnated layer surface with respect to the surface of the porous support + X ′ or −X ′ / thickness t of the porous support) × 100

In the separator for electrochemical devices of the present invention, the average position of the resin composition-impregnated layer surface relative to the porous support surface relative to the thickness of the porous support measured by the above method is the both surfaces of the separator, It is preferably -8% or more, more preferably -5% or more, still more preferably -3% or more, and particularly preferably -1% or more. Thereby, durability of a separator can be made more excellent. In addition, the average position is preferably 20% or less, more preferably 10% or less, on each of both surfaces of the separator. Thereby, resistance of a separator can be made lower. In the separator for electrochemical devices of the present invention, the average position is preferably -5% or more and 5% or less, and is -3% or more and 3% or less on at least one of both surfaces of the separator. More preferably, it is more preferably −1% or more and 1% or less.

As will be described later, the separator for an electrochemical device of the present invention is usually coated with a resin composition according to the present invention on a release substrate, and then contacted and impregnated with a porous support, and the film was dried. Further, it can be obtained by peeling from the peeling substrate. Here, the average position of the resin composition-impregnated layer surface based on the porous support surface measured by the above method is the amount, viscosity, surface tension, and hydrophilicity of the porous support material. It can adjust suitably by adjusting property etc.

In the separator for an electrochemical element of the present invention, in the cross section, the average position of the surface of the resin composition impregnated layer with respect to the thickness of the porous support on each of both surfaces of the separator is within the predetermined range. As long as it is within, a part of the gap may be included. Air entrained during kneading of the separator forming material for an electrochemical element may remain to form voids in the separator, or voids may be generated between the inorganic compound particles contained in the resin composition.

Below, the constituent material of the separator for electrochemical elements of this invention is demonstrated, and the manufacturing method is then demonstrated.

[Resin composition]
(polymer)
The resin composition according to the present invention includes a polymer. Various polymers can be used as the polymer, and any of thermoplastic and thermosetting may be used. For example, conjugated diene polymer, (meth) acrylic polymer, fluorine-containing ethylene polymer, polysulfone polymer Polymers, polyether ketones and the like can be mentioned, among which at least one selected from the group consisting of conjugated diene polymers, (meth) acrylic polymers, fluorine-containing ethylene polymers, and polysulfone polymers. Preferably, it is a conjugated diene polymer. In addition, it is preferable that the said polymer functions as a binder polymer.

The conjugated diene polymer has a monomer unit derived from a conjugated diene monomer.
The conjugated diene monomer is preferably an aliphatic conjugated diene monomer. Examples of the aliphatic conjugated diene monomer include 1,3-butadiene, isoprene, 2-chloro-1,3-butadiene, chloroprene and the like, and among these, 1,3-butadiene is preferable. Conjugated diene monomers may be used alone or in combination of two or more.

The conjugated diene-based polymer can be obtained by using one or more monomer units derived from a conjugated diene-based monomer. However, the uniformity of the composition according to the present invention and the mechanical strength of the obtained separator can be increased. For example, it is preferable to further include a monomer unit derived from an aromatic vinyl monomer from the viewpoint of appropriately increasing the elongation rate and stress.

Examples of the aromatic vinyl monomer include styrene, α-methyl styrene, o-methyl styrene, m-methyl styrene, p-methyl styrene, o-ethyl styrene, m-ethyl styrene, p-ethyl styrene, o-methoxy styrene. , M-methoxystyrene, p-methoxystyrene, o-ethoxystyrene, m-ethoxystyrene, p-ethoxystyrene, o-fluorostyrene, m-fluorostyrene, p-fluorostyrene, o-chlorostyrene, m-chlorostyrene P-chlorostyrene, o-bromostyrene, m-bromostyrene, p-bromostyrene, o-acetoxystyrene, m-acetoxystyrene, p-acetoxystyrene, o-tert-butoxystyrene, m-tert-butoxystyrene, p-tert-butoxys Ren, o-tert-butylstyrene, m-tert-butylstyrene, p-tert-butylstyrene and vinyltoluene. Among these, styrene and α-methylstyrene are preferable in that the heat resistance and mechanical strength of the separator can be increased and the elongation rate and stress are suitably adjusted. These aromatic vinyl monomers may be used alone or in combination of two or more.

The conjugated diene polymer preferably has a mass ratio of a monomer unit derived from an aliphatic conjugated diene monomer and a monomer unit derived from an aromatic vinyl monomer of, for example, 1/9 or more and 9/1 or less. / 8 or more and 8/2 or less is more preferable, and 3/7 or more and 7/3 or less is still more preferable.

The conjugated diene-based polymer is a carboxy-modified conjugated diene having a carboxyl group and / or a carboxylate group that is a salt thereof from the viewpoint of increasing the bonding strength between the inorganic compound and the polymer and further improving the strength of the separator. The polymer is preferably a polymer, for example, more preferably a monomer unit derived from an unsaturated monomer having a carboxylate group and / or a carboxylate group that is a salt thereof. Examples of the unsaturated monomer having a carboxylate group which is a carboxyl group and / or a salt thereof include unsaturated monocarboxylic acid (salt) such as (meth) acrylic acid (salt); maleic acid (salt), fumaric acid (salt) ), Unsaturated dicarboxylic acids (salts) such as itaconic acid (salts), and the like, and these may be used alone or in combination of two or more.

The conjugated diene polymer has a mass ratio of 0.2% by mass of the monomer unit derived from the unsaturated monomer having a carboxylate group and / or a carboxylate group that is a salt thereof from the viewpoint of further improving the strength of the separator. It is preferable that it is above, it is more preferable that it is 0.3 mass% or more, and it is still more preferable that it is 0.5 mass% or more. Further, from the viewpoint of making the ionic conductivity of the separator more excellent, the mass ratio is preferably 10% by mass or less, more preferably 8% by mass or less, and 5% by mass or less. Further preferred.

Examples of the conjugated diene polymers include styrene-butadiene polymers, carboxy-modified styrene-butadiene polymers, polybutadiene polymers, carboxy-modified polybutadiene polymers, polyisoprene polymers, carboxy-modified polyisoprene polymers, acrylonitrile-butadiene polymers, One type or two or more types such as carboxy-modified acrylonitrile-butadiene-based polymers can be suitably used. Among these, styrene-butadiene polymers and carboxy-modified styrene-butadiene polymers are preferable, and carboxy-modified styrene-butadiene polymers are particularly preferable.

The conjugated diene polymer is a monomer unit derived from an aliphatic conjugated diene monomer, a monomer unit derived from an aromatic vinyl monomer, a monomer unit derived from an unsaturated monomer having a carboxylate group which is a carboxyl group and / or a salt thereof. The monomer unit may be derived from other unsaturated monomers.

Examples of other unsaturated monomers include sulfonic acid group-containing vinyl monomers such as acrylamide methylpropane sulfonic acid and styrene sulfonate; methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, N-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, (meth) acrylic (Meth) acrylic acid ester monomers such as octyl acid, 2-ethylhexyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate; 2-hydroxyethyl (meth) acrylate, (meth) acrylic acid Hydroxyl-containing vinyl monomers such as 4-hydroxybutyl; (meth) acrylic Nitrile group-containing vinyl monomers such as nitrile; (meth) acrylamide monomers such as (meth) acrylamide, N-methylol (meth) acrylamide, N-ethylol (meth) acrylamide, dimethyl (meth) acrylamide, diethyl (meth) acrylamide; Bifunctional vinyl monomers such as divinylbenzene, ethylene glycol dimethacrylate, isopropylene glycol diacrylate, tetramethylene glycol dimethacrylate; 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltri Examples thereof include vinyl monomers containing an alkoxysilane group such as ethoxysilane.

In 100% by mass of the conjugated diene polymer, the mass ratio of other unsaturated monomer-derived monomer units is preferably 30% by mass or less, more preferably 5% by mass or less, and 0.1% by mass. More preferably, it is as follows.

Although the said (meth) acrylic-type polymer should just have a monomer unit derived from the monomer which has a (meth) acryloyl group, as a typical thing, the monomer unit derived from a (meth) acrylic acid ester monomer is a main component. (Meth) acrylic acid ester polymer to be used.

When the main component is a monomer unit derived from a (meth) acrylate monomer, the content of the monomer unit derived from a (meth) acrylate monomer is 50% by mass or more in 100% by mass of the (meth) acrylate polymer. Say there is.
Specifically, the (meth) acrylic acid ester monomer is as described above as one of the other unsaturated monomers in the carboxy-modified conjugated diene polymer.

In addition to the monomer unit derived from the (meth) acrylic acid ester monomer, the (meth) acrylic polymer is a monomer unit derived from an unsaturated monomer having a carboxylate group which is a carboxy group and / or a salt thereof, and other unsaturated units. You may have a monomer unit derived from a monomer. From the viewpoint of increasing the bonding strength between the inorganic compound and the polymer and improving the strength of the separator, the (meth) acrylic polymer is unsaturated having a carboxylate group and / or a carboxylate group that is a salt thereof. A (meth) acrylic polymer having a monomer unit derived from a monomer is preferred.

Examples of the other unsaturated monomers include those described above as the other unsaturated monomers in the carboxy-modified conjugated diene polymer (excluding the (meth) acrylic acid ester monomer).

The fluorine-containing ethylene-based polymer has a structure in which at least a part of hydrogen atoms of polyethylene is substituted with fluorine atoms, and examples thereof include polyvinylidene fluoride and polytetrafluoroethylene.

The polysulfone-based polymer is a polymer having a sulfonyl group as a repeating unit, and examples thereof include polysulfone (PSU), polyethersulfone (PESU), and polyphenylsulfone (PSSU).
The polyether ketone is a polymer having an ether bond and a ketone bond, and examples thereof include polyether ketone ketone and polyether ether ketone.

The above-mentioned polymer can be produced by copolymerizing a monomer component forming a constituent unit contained in the polymer in the presence of a radical generator, and graft-modifying it as necessary.
The method for polymerizing the monomer component is not particularly limited, and examples thereof include an aqueous solution polymerization method, an emulsion polymerization method, a reverse phase suspension polymerization method, a suspension polymerization method, a solution polymerization method, and a bulk polymerization method.

The mass ratio of the polymer is preferably 1% by mass or more, preferably 2% by mass or more, in 100% by mass of the separator for electrochemical devices of the present invention, from the viewpoint of suitably adjusting the ion conductivity and durability of the separator. Is more preferably 3% by mass or more, still more preferably 5% by mass or more, and particularly preferably 7% by mass or more. The mass ratio is preferably 40% by mass or less, more preferably 30% by mass or less, still more preferably 20% by mass or less, and particularly preferably 9% by mass or less.

(Inorganic compounds)
The resin composition according to the present invention contains an inorganic compound. The inorganic compound is preferably at least one selected from the group consisting of oxides, hydroxides, layered double hydroxides, and phosphate compounds, for example. In addition, in this specification, a hydroxide is a compound which has a hydroxyl group, Comprising: A thing other than a layered double hydroxide is said.

Examples of the oxide include lithium oxide, sodium oxide, potassium oxide, magnesium oxide, calcium oxide, barium oxide, scandium oxide, yttrium oxide, lanthanoid oxide, titanium oxide, zirconium oxide, niobium oxide, ruthenium oxide, nickel oxide, Palladium oxide, copper oxide, cadmium oxide, boron oxide, aluminum oxide, gallium oxide, indium oxide, thallium oxide, silicon oxide, germanium oxide, tin oxide, lead oxide, phosphorus oxide, bismuth oxide, etc. Or 2 or more types can be used. Among them, a composition that is stable even when the composition and the electrochemical device are formed under alkaline conditions is preferable. For example, magnesium oxide, calcium oxide, titanium oxide, zirconium oxide, and aluminum oxide are preferable, and magnesium oxide and titanium oxide are preferable. Zirconium oxide is more preferable. Zirconium oxide may be a solid solution of an element such as yttrium, scandium, or ytterbium, or may have an oxygen defect.

Examples of the hydroxide include lithium hydroxide, sodium hydroxide, potassium hydroxide, magnesium hydroxide, calcium hydroxide, barium hydroxide, scandium hydroxide, yttrium hydroxide, lanthanide hydroxide, titanium hydroxide, and water. Zirconium oxide, niobium hydroxide, ruthenium hydroxide, nickel hydroxide, palladium hydroxide, copper hydroxide, cadmium hydroxide, boric acid, aluminum hydroxide, gallium hydroxide, indium hydroxide, thallium hydroxide, silicic acid, water Examples thereof include germanium oxide, tin hydroxide, lead hydroxide, phosphoric acid, bismuth hydroxide, and one or more of these can be used. Among them, those having low solubility under alkaline conditions are preferable, for example, magnesium hydroxide, calcium hydroxide, titanium hydroxide, and zirconium hydroxide are preferable, and magnesium hydroxide is more preferable.

The layered double hydroxide has the following general formula:
[M ¹ _1-x M ² _x (OH) ₂ ] (A ⁿ⁻ ) _{x / n} · mH ₂ O
(M ¹ represents a divalent metal ion that is ^one of Mg, Fe, Zn, Ca, Li, Ni, Co, Cu, and Mn. M ² represents Al, Fe, Mn, Co, Cr, or In. ^{.A n-is} representative of the trivalent metal ion is any _{^{one, Cl -, NO 3 -,}} CO 3 2-, COO -. 1 or more valences such as, represents a trivalent following anions Among ^{them, a n-is} It is preferable to represent a divalent or less anion, where m is a number of 0 or more, n is a number of 1 or more and 3 or less, and x is a number of 0.20 or more and 0.40 or less. Such layered double hydroxides include, for example, hydrotalcite, manassite, moscoleite, stichtite, shoglenite, barbournite, pyroaulite, iomite, chloromagalminite, hydrotalcite, and the like. Karma Ito, Green Last 1, Bercherin, Tacobite, Livesite, Honesite, Yardlite, Meixenite and the like, and one or more of these can be used. Among these, hydrotalcite in which M ¹ in the general formula is Mg and M ² is Al is preferable because it is industrially easy to use.
These layered hydroxides are, for example, compounds dehydrated by baking at 150 ° C. or more and 900 ° C. or less, compounds obtained by decomposing anions in the interlayer, and anions in the interlayer into hydroxide ions, etc. It may be an exchanged compound.
A compound having a functional group such as a hydroxyl group, an amino group, a carboxy group, or a silanol group may be coordinated with the layered double hydroxide. The layered double hydroxide may have an organic substance in the interlayer.

Examples of the phosphoric acid compound include hydroxyapatite (Ca ₁₀ (PO4) ₆ (OH) ₂ ), magnesium hydroxyapatite in which a part or all of the calcium ions of hydroxyapatite are substituted with magnesium, strontium hydroxyapatite substituted with strontium, Examples thereof include barium hydroxyapatite substituted with barium. Of these, hydroxyapatite and magnesium hydroxyapatite are preferable.

Above all, the inorganic compound is more preferably a layered double hydroxide and / or hydroxide. The inorganic compound is more preferably a hydroxide from the viewpoint of further improving the strength of the separator, and a layered double hydroxide from the viewpoint of further improving the ionic conductivity of the separator. More preferably.

The inorganic compound is in the form of particles, and examples of the shape include fine powder, powder, granule, granule, scale, polyhedron, rod, and curved surface.
The inorganic compound preferably has an average particle size of 5 μm or less. The average particle diameter is more preferably 2 μm or less, and further preferably 1 μm or less. The average particle diameter is preferably 0.001 μm or more, more preferably 0.01 μm or more, and further preferably 0.1 μm or more.
The average particle size may be any of the average particle size of the inorganic compound powder or inorganic compound dispersion before being mixed with other components in order to obtain the composition of the present invention. It can be measured according to the method.

The average particle size in the above range is, for example, a method of pulverizing the particles with a ball mill or the like, dispersing the obtained coarse particles in a dispersant to a desired particle size, In addition to the method of selecting the particle diameter by sieving the coarse particles, etc., it is possible to optimize the preparation conditions at the stage of producing the particles to obtain (nano) particles having a desired particle diameter.

The mass ratio of the inorganic compound is preferably 30% by mass or more in 100% by mass of the separator for electrochemical devices of the present invention from the viewpoint of improving the durability and ionic conductivity of the separator. The mass ratio is more preferably 50% by mass or more, and still more preferably 55% by mass or more. Moreover, it is preferable that this mass ratio is 95 mass% or less. The mass ratio is more preferably 90% by mass or less, still more preferably 80% by mass or less, and particularly preferably 65% by mass or less.

[Porous support]
The separator for electrochemical devices of the present invention further has a porous support. The porous support is not particularly limited. For example, a polyolefin polymer such as polyethylene, polypropylene, ethylene-propylene copolymer, and cyclic polyolefin polymer; a polyvinyl alcohol polymer such as vinylon; an aliphatic polyamide; an aromatic polyamide; Styrene-based polymers; polyester-based polymers; polysulfone-based polymers such as polysulfone, polyethersulfone, and polyphenylsulfone; non-woven fabrics, woven fabrics, and microporous films made of resin materials such as polyphenylene sulfide-based polymers Among these, polyolefin polymers and polyvinyl alcohol polymers are more preferable.
The separator for an electrochemical element of the present invention is obtained by at least partially integrating a resin composition-impregnated layer obtained by impregnating a porous support with the resin composition according to the present invention and a porous support. . In the separator for electrochemical devices of the present invention, the resin composition according to the present invention fills at least part of the pores in the porous support.

The mass ratio of the porous support is preferably 5% by mass or more, more preferably 10% by mass or more, and more preferably 15% by mass or more in 100% by mass of the separator for electrochemical devices of the present invention. More preferably, it is particularly preferably 25% by mass or more. The mass ratio is preferably 50% by mass or less, more preferably 40% by mass or less, and further preferably 35% by mass or less.

(Other ingredients)
The separator for electrochemical devices of the present invention may further contain other components such as conductive carbon and conductive ceramics.
The content of other components in the separator for electrochemical devices of the present invention is preferably 10% by mass or less in 100% by mass of the separator from the viewpoint of the strength of the separator. More preferably, it is 5 mass% or less, More preferably, it is 1 mass% or less, Most preferably, it is 0.1 mass% or less.

The separator for electrochemical elements of the present invention preferably has an average film thickness of 10 μm to 1 mm. When the thickness is 10 μm or more, the occurrence of breakage during film formation can be sufficiently prevented. Further, if it is 1 mm or less, it is advantageous from the viewpoint of cost, and ion transmission ability is sufficiently excellent. The average film thickness is more preferably 15 μm or more, further preferably 20 μm or more, and particularly preferably 25 μm or more. Further, the average film thickness is more preferably 800 μm or less, further preferably 500 μm or less, and particularly preferably 200 μm or less.
The said average film thickness is an average film thickness of arbitrary 5 points | pieces measured using the scanning electron microscope.

The separator for an electrochemical element of the present invention preferably has a resistance value of 0.1 to ⁵ Ωcm ² . The resistance is more preferably 3Omucm ² or less, still more preferably 2Omucm ² or less, particularly preferably 1 .OMEGA.cm ² or less.
The resistance value can be measured according to the method described in Examples.

The separator for an electrochemical element of the present invention is preferably for use as a separator used in an electrochemical element comprising an aqueous electrolyte.

(Method for producing separator for electrochemical device of the present invention)
The separator for electrochemical devices of the present invention can be manufactured by preparing a resin composition used for obtaining a separator for electrochemical devices by forming a film, and forming the resin composition into a film by a method described later. .
First, the raw materials of the resin composition according to the present invention (inorganic compound, polymer, and other components according to the present invention) are mixed. For mixing, a mixer, blender, kneader, sand mill, bead mill, ready mill, roll mill, ball mill, or the like can be used. During mixing, water, an organic solvent such as methanol, ethanol, propanol, isopropanol, butanol, hexanol, tetrahydrofuran, N-methylpyrrolidone, or a mixed solvent of water and an organic solvent may be added as a medium.
After mixing, if necessary, filtration, defoaming and the like can be performed to obtain the resin composition according to the present invention.
In addition, you may manufacture the dispersion of an inorganic compound before mixing. For example, an inorganic compound and, if necessary, a dispersant for the inorganic compound are mixed. By producing the inorganic compound dispersion before mixing, it is possible to suppress destabilization of the polymer during the preparation. The above-mentioned equipment and medium can be used for mixing.

The method for producing a film from the resin composition according to the present invention includes the resin composition according to the present invention, for example, a cast coating method, a spin coating method, a blade coating method, a dip coating method, a roll coating method, a bar coating method, It can be coated on a release substrate such as a polyethylene terephthalate (PET) film by a conventionally known method such as a comma coating method, a die coating method, an ink jet method, or a wet laminating method. The surface of the resin composition film coated on the release substrate is contacted and impregnated with the porous support, and the film is dried and then peeled off from the release substrate to produce the separator for an electrochemical device of the present invention. can do.

The separator after film formation may be heated as necessary. The heating temperature and heating time may be set as appropriate.

<Electrochemical element>
This invention is also an electrochemical element comprised including the separator for electrochemical elements of this invention.
Examples of the electrochemical element of the present invention include a battery; a capacitor such as an electrolytic capacitor; a capacitor such as an electric double layer capacitor and a lithium ion capacitor; a sensor such as a humidity sensor and a gas sensor; a fuel cell such as an alkaline fuel cell; An electrolysis device such as an electrolysis device may be mentioned.

The aqueous electrolyte is not particularly limited as long as water is used as a main component of the electrolyte raw material, which is usually used as an aqueous electrolyte of an electrochemical element, and may contain an organic solvent together with water. The use of water as the main component of the electrolyte solution raw material means that the mass ratio of water is 50% by mass or more in 100% by mass of the aqueous electrolyte solution. The mass ratio is preferably 80% by mass or more. Examples of the organic solvent include ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, γ-butyrolactone, dimethoxymethane, diethoxymethane, dimethoxyethane, tetrahydrofuran, methyltetrahydrofuran, diethoxyethane, dimethylsulfoxide, sulfolane, acetonitrile, benzoate. Nitriles, ionic liquids, fluorine-containing carbonates, fluorine-containing ethers, polyethylene glycols, fluorine-containing polyethylene glycols and the like can be mentioned, and these can be used alone or in combination.

Especially, it is preferable that the electrochemical element of this invention is an electrochemical element comprised including the electrolyte solution which uses only water as an electrolyte solution raw material. Where the electrolyte solution using only water as the electrolyte solution raw material has higher thermal safety, more stable electrochemical characteristics can be obtained by using the electrochemical element separator of the present invention.

The aqueous electrolyte is preferably an alkaline electrolyte, for example. Examples of the alkaline electrolyte include a potassium hydroxide aqueous solution, a sodium hydroxide aqueous solution, a lithium hydroxide aqueous solution, a zinc sulfate aqueous solution, a zinc nitrate aqueous solution, a zinc phosphate aqueous solution, and a zinc acetate aqueous solution. These can be used alone. It can also be used as an aqueous solution in which two or more of these solutes are mixed.

(battery)
The electrochemical element of the present invention is preferably a battery, for example. The case where the electrochemical device of the present invention is a battery will be described in detail below.
A battery usually includes a positive electrode. As the active material of the positive electrode, those normally used as the positive electrode active material of the primary battery or the secondary battery can be used, and are not particularly limited. For example, oxygen (when oxygen becomes the positive electrode active material, the positive electrode is oxygen Perovskite type compounds, cobalt-containing compounds, iron-containing compounds, copper-containing compounds, manganese-containing compounds, vanadium-containing compounds, nickel-containing compounds, iridium-containing compounds, platinum-containing compounds; platinum-containing compounds; Containing compound; silver-containing compound; air electrode composed of carbon-containing compound); nickel-containing compound such as nickel oxyhydroxide, nickel hydroxide, cobalt-containing nickel hydroxide; manganese-containing compound such as manganese dioxide; Silver; Lithium-containing compounds such as lithium cobaltate; Iron-containing compounds; Examples include zinc species such as lead.
Moreover, it is one of the suitable embodiments of the present invention that the positive electrode active material is oxygen, such as an air battery.

The battery is usually configured to further include a negative electrode. As the negative electrode active material, those normally used as the negative electrode active material of the battery such as carbon, lithium, sodium, magnesium, zinc, nickel, tin, cadmium, hydrogen storage alloy, silicon-containing material and the like can be used. For example, the present invention can be suitably applied to a battery using an active material that may generate dendrite in association with an electrode reaction such as zinc, lithium, nickel, magnesium, cadmium, or the like as a negative electrode active material. . Especially, it is preferable that a negative electrode active material contains a zinc compound.

Electrodes such as a positive electrode and a negative electrode constituting the battery can be produced by forming an active material layer on a current collector.
Current collectors that make up the electrode include (electrolytic) copper foil, copper mesh (expanded metal), foamed copper, punched copper, copper alloys such as brass, brass foil, brass mesh (expanded metal), foamed brass, punched brass , Nickel foil, corrosion-resistant nickel, nickel mesh (expanded metal), punching nickel, metal zinc, corrosion-resistant metal zinc, zinc foil, zinc mesh (expanded metal), (punched) steel sheet, non-woven fabric imparted with conductivity; Ni, Zn, Sn, Pb, Hg, Bi, In, Tl, brass added (electrolytic) copper foil, copper mesh (expanded metal), copper alloy such as foamed copper, punched copper, brass, brass foil, brass mesh (expanded metal) ), Foamed brass, punched brass, nickel foil, corrosion-resistant nickel, nickel mesh (expanded) Tar), punching nickel, metallic zinc, corrosion-resistant metallic zinc, zinc foil, zinc mesh (expanded metal), (punching) steel sheet, non-woven fabric; plated with Ni, Zn, Sn, Pb, Hg, Bi, In, Tl, brass, etc. (Electrolytic) copper foil copper mesh (expanded metal), foamed copper, punched copper, brass and other copper alloys, brass foil, brass mesh (expanded metal), foamed brass, punched brass, nickel foil, corrosion resistant nickel, nickel mesh (Expanded metal), punched nickel, metal zinc, corrosion-resistant metal zinc, zinc foil, zinc mesh (expanded metal), (punched) steel sheet, non-woven fabric; silver; current collector and container for alkaline (storage) battery and air zinc battery Examples include materials used.

The form of the battery is usually a secondary battery (storage battery) that can be charged and discharged. The battery of the present invention uses a general secondary battery, a mechanical charge (mechanical replacement of a zinc negative electrode), a third electrode (a positive electrode, an electrode suitable for charging) Any form such as one using electrodes suitable for discharge) may be used.

(Fuel cell or electrolyzer)
The case where the electrochemical element of the present invention is a fuel cell or an electrolyzer will be described in detail below.
The separator for electrochemical elements of the present invention is suitably used as a member for alkaline fuel cells and alkaline water electrolysis devices. Examples of the alkaline fuel cell and alkaline water electrolysis apparatus include an anode, a cathode, and a separator for an electrochemical element of the present invention disposed between the anode and the cathode. More specifically, the alkaline fuel cell and the alkaline water electrolysis apparatus have an anode chamber in which an anode exists and a cathode chamber in which a cathode exists, which are separated by the separator for electrochemical elements of the present invention.
Examples of the anode and the cathode include known electrodes including a conductive substrate containing nickel or a nickel alloy.

[Fuel cell power generation method]
The method of power generation performed using the alkaline fuel cell including the separator for electrochemical devices of the present invention is not particularly limited, and can be performed by a known method. For example, an alkaline fuel cell including the above-described separator for an electrochemical element of the present invention is filled with an electrolytic solution, and an oxidant (for example, oxygen) and a fuel (for example, hydrogen) are supplied to the anode and the cathode, respectively, in the electrolytic solution. By doing so, it is possible to generate electricity.

[Electrolysis method of water electrolyzer]
The method of electrolyzing water using an alkaline water electrolysis apparatus including the separator for electrochemical elements of the present invention is not particularly limited, and can be performed by a known method. For example, it can be performed by filling an alkaline water electrolysis apparatus including the above-described separator for an electrochemical element of the present invention with an electrolytic solution and applying a current in the electrolytic solution.

The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to these examples. Unless otherwise specified, “part” means “part by weight” and “%” means “mass%”.

(Measuring method)
In each measurement shown below, the measurement location passes through the center of the coating width at the time of coating the release composition of the resin composition, and any three locations with a width of 80 μm in the cross section along the flow direction of the resin composition, Two arbitrary positions with a width of 80 μm in the cross section along the direction orthogonal to the flow direction were measured and calculated, and the measurement result described the average value.

<Thickness>
A 400 × magnified photograph was taken so that the entire thickness of the separator could be observed in one field of view using a scanning electron microscope (FIG. 3 shows an example of the magnified photograph). The thickness of the separator was calculated from the obtained image.
Further, the reference line A and the reference line A ′ were determined by the method described below, and the distance t (μm) between the reference line A and the reference line A ′ was calculated, and this was used as the thickness of the porous support. Note that the distance t is the shortest distance between the reference lines in the region having a width of 80 μm when the reference line A and the reference line A ′ are not parallel.

<Filling rate>
The resin composition based on the surface of the porous support was calculated by calculating the X value, which is the distance between the reference line A, the filling line B, and the reference line A and the filling line B, for the five measurement points by the method described below. The position + X or −X on the surface of the material impregnated layer was determined, and the filling rate Y was calculated by the following formula.
Filling rate Y (%) = Position of resin composition impregnated layer surface with reference to porous support surface + X or −X / porous support thickness t × 100

<Reference line A>
Among the cross section obtained by cutting perpendicularly to the surface of the separator, a magnified photograph of 1500 times was taken using a scanning electron microscope for a region having a width of 80 μm. The field of view was 30% or more of the total thickness of the separator from the surface on one side of the separator.
Of the porous support part in the obtained enlarged photograph, a point closest to the surface of the separator in the region on the left side of the midpoint in the width direction, and a point closest to the surface of the separator in the region on the right side of the midpoint A straight line having a length in the width direction between both end portions of 60 μm or more was defined as a reference line A. The point closest to the surface of the separator is the end point of the porous support portion closest to the surface when the surface of the separator is made of a resin composition, and the surface of the separator is porous. In the case where the end portion of the support portion is used, the end portion of the porous support portion constituting the separator surface is the closest point to the separator surface (the distance from the separator surface is 0). It is an arbitrary point at the end of the porous support portion constituting the surface of the substrate.

<Filling line B>
When a line parallel to the reference line A is sequentially scanned from the side opposite to the surface side of the reference line A to the surface side of the reference line A, a space portion (nonwoven fabric fiber) on the parallel line with respect to the length of the parallel line The boundary line where the ratio of the total length of the portion having no porous base material and composition such as 10% or less ends is the filling line B. In addition, when two or more filling parts existed, the filling line B was a line having the shortest distance from the reference line A among the boundary lines where the filling part was terminated.

<X value and position of resin composition-impregnated layer surface with reference to porous support surface>
The distance between the reference line A and the filling line B was calculated from the captured image as the X value. The position of the resin composition-impregnated layer surface with respect to the surface of the porous support is -X when the filling line B is in front of the reference line A (inside the membrane) in the scanning direction of the parallel lines. When exceeding the reference line A (when outside the membrane), it was set as + X.

Similarly, for the other surface, the reference line A ′ and the filling line B ′ are obtained, and the distance X ′ and the position + X ′ or −X ′ of the resin composition-impregnated layer surface with respect to the porous support surface are determined. Asked.

<Outline of measurement procedure>
The outline of the measurement procedure is as follows.
Select a region (width 80 μm) to be a measurement location.
The reference line A and the filling line B are determined with the one surface side as the imaging field of view, and the distance X between them and the positional relationship between the reference line A and the filling line B are read. Next, the imaging field of view is moved in the thickness direction toward the opposite surface, the reference line A ′ and the filling line B ′ are determined, and the distance X ′ between them, the position of the reference line A ′ and the filling line B ′. Read the relationship.
The magnification is lowered, the magnification is lowered in the thickness direction to a magnification at which the entire porous support can be confirmed, the reference lines A and A ′ are determined, and the distance between them (= thickness t) is read.
Y (y1) of one surface and Y ′ (y1 ′) of the other surface are obtained.
For the other four regions, the reference line A, filling lines B and X, the positional relationship between the reference line A and the filling line B, the reference line A ′, the filling lines B ′ and X ′, the reference line A ′ and the filling line The positional relationship with B ′, the thickness t, Y (y2 to y5), and Y ′ (y2 ′ to y5 ′) are obtained.
A simple average of y1 to y5 and a simple average of y1 'to y5' are obtained.

<Resistance value>
The resistance value (Ωcm ² ) was measured under the following conditions.
Cell configuration Working electrode: Ni plate Counter electrode: Ni plate Electrolyte solution: 6.7 mol / L KOH aqueous solution saturated with zinc oxide Measurement sample: Immersion in the electrolyte solution overnight Effective area: φ15 mm
・ Measure AC impedance. After leaving still for 30 minutes in a 25 degreeC thermostat, it measured on condition of the following.
Applied voltage: 10 mV vs. Open circuit voltage frequency range: 100 kHz to 100 Hz
The resistance value (R) was calculated by the following equation from the intercept component (Ra) obtained by impedance and the intercept component (Rb) when no measurement sample was added.
R = (Ra−Rb) × 1.77

<Charge / discharge test>
A negative electrode made of zinc oxide and polytetrafluoroethylene (PTFE) kneaded at a mass ratio of 96: 4 is attached to punching nickel, and an ion conductive film formed by a separator is arranged, and nickel is used as a counter electrode. A battery cell using an Ag / AgO electrode as a positive electrode and a reference electrode was constructed. A current density of 30 mA / cm2 was passed between the counter electrode and the negative electrode, and a charge / discharge test with an electric capacity of 25% with respect to the negative electrode capacity was performed. Charging / discharging was repeated at an electric capacity of 25% with respect to the negative electrode capacity, and the number of cycles when the positive electrode and the negative electrode were short-circuited was evaluated as the life.

[Preparation Example 1]
100 parts by weight of magnesium hydroxide particles, 3 parts by weight of a polyacrylate aqueous solution (non-volatile content 40%) and 46 parts by weight of ion-exchanged water are weighed and dispersed for 1 hour using a sand mill, followed by filtration and hydroxylation. A magnesium particle aqueous dispersion was obtained. 100 parts by mass of the obtained magnesium hydroxide particle aqueous dispersion and 17.5 parts by mass of a carboxy-modified styrene-butadiene polymer aqueous dispersion (non-volatile content: 48%) were weighed and mixed, and then filtered and vacuum degassed. And a film forming composition was obtained.

[Example 1]
The obtained film-forming composition was coated on a polyethylene terephthalate (PET) film with a comma coater so that the weight value of the film-forming composition after drying was 7.5 mg / cm ^2. nonwoven fabric made of polyolefin-based fibers above (weighing value: 4 mg / cm ^2, thickness: 90 [mu] m) after contacting, dried, by separating the non-woven fabric by coating a PET film, integrated nonwoven and coating A separator was obtained. The film thickness of the obtained separator was 100 μm. The resistance was 0.6 Ωcm ² . The filling rate into the nonwoven fabric was + 9% and 0% on each side. As a result of conducting a charge / discharge test of the battery using the obtained separator, the life was 300 cycles. The results are shown in Table 1.

[Example 2]
A separator was obtained in the same manner as in Example 1, except that the weight value of the film-forming composition after drying was adjusted to 10.5 mg / cm ² . The separator obtained had a film thickness of 120 μm. Resistance was 0.8Ωcm ^2. The filling rate into the nonwoven fabric was + 28% and + 2% on each side. As a result of conducting a charge / discharge test of the battery using the obtained separator, the lifetime was 280 cycles. The results are shown in Table 1.

[Example 3]
A separator was obtained in the same manner as in Example 1 except that the weight value of the film-forming composition after drying was adjusted to 6.5 mg / cm ^{2 in} Example 1. The separator obtained had a film thickness of 95 μm. The resistance was 0.5 Ωcm ² . The filling rate into the nonwoven fabric was + 2% and -6% on each side. As a result of conducting a charge / discharge test of the battery using the obtained separator, the lifetime was 260 cycles. The results are shown in Table 1.

[Comparative Example 1]
A separator was obtained in the same manner as in Example 1, except that the weight value of the film-forming composition after drying was adjusted to 4.5 mg / cm ² . The thickness of the obtained separator was 90 μm. Resistance was 0.3Ωcm ^2. The filling rate into the nonwoven fabric was + 2% and −25% on each side. As a result of conducting a charge / discharge test of the battery using the obtained separator, the lifetime was 135 cycles. The results are shown in Table 1.

[Comparative Example 2]
A separator was obtained in the same manner as in Example 1, except that the weight value of the film-forming composition after drying was adjusted to 14 mg / cm ² . The film thickness of the obtained separator was 145 μm. The resistance was 2.3 Ωcm ² . The filling rate into the nonwoven fabric was + 55% and + 5% on each side. As a result of conducting a charge / discharge test using the obtained separator, the lifetime was 80 cycles. The results are shown in Table 1.

As described above, by forming a separator in which the filling rate of the composition impregnated into the nonwoven fabric is in the range of −10% to + 30%, and forming a battery using the obtained separator, the life is long and long The battery which was excellent in use of was able to be obtained. Such a separator can be suitably applied to various electrochemical devices as a separator having both low resistance and durability.

Claims (3)

A separator used in an electrochemical element,
The separator has a porous support and a resin composition-impregnated layer in which the porous support is impregnated with a resin composition containing a polymer and an inorganic compound, and is measured on each of both surfaces of the separator by the following method. The average position of the surface of the resin composition-impregnated layer relative to the thickness of the porous support relative to the thickness of the porous support is in the range of −10% or more and + 30% or less. Separator.
Method for measuring average position of resin composition-impregnated layer surface based on porous support surface relative to thickness of porous support:
(1) In a cross section obtained by cutting perpendicularly to the surface of the separator, any five regions each having a length in the width direction of 80 μm are selected using a scanning electron microscope.
(2) For each region, a porous support in a region on the left side of the center point in the width direction on one surface side of the separator on an enlarged photograph of one surface portion of the separator, taken using a scanning electron microscope A straight line having a length in the width direction between both end portions of 60 μm or more is defined as a reference line A.
(3) When a line parallel to the reference line A is scanned from the side opposite to the one surface side of the separator to the one surface side of the separator on the enlarged photograph of (2), the length of the parallel line A filling line B is defined as a boundary line where a filling portion in which the total length of the space portions on the parallel line is 10% or less is terminated.
(4) A distance X between the reference line A and the filling line B is calculated. When the filling line B is in front of the reference line A in the scanning direction of the parallel lines, the position of the resin composition impregnated layer surface with respect to the surface of the porous support is -X, and when the reference line A is exceeded + X.
(5) For each region, even in an enlarged photograph of the surface portion opposite to the one surface of the separator, taken using a scanning electron microscope, the reference line A ′ is the same as in (2) to (4). The filling line B ′ is obtained, the distance X ′ between the reference line A ′ and the filling line B ′ is calculated, and the position + X ′ or −X ′ of the resin composition-impregnated layer surface with respect to the porous support surface is determined. Decide.
(6) For each region, the distance between the reference line A and the reference line A ′ in the enlarged photograph that can be observed with one field of view in the thickness direction of the separator taken with a scanning electron microscope is the thickness of the porous support. Let t.
(7) For each region, the ratio Y of the position + X or -X of the resin composition-impregnated layer surface with respect to the porous support surface relative to the thickness t of the porous support, and the thickness t of the porous support The ratio Y ′ of the position + X ′ or −X ′ of the resin composition impregnated layer surface with respect to the surface of the porous support is determined, and the average value of the ratio Y and the average value of the ratio Y ′ are respectively determined. The average position of the surface of the resin composition-impregnated layer based on the porous support surface relative to the thickness of the porous support on the surface. An electrochemical element comprising the electrochemical element separator according to claim 1. The electrochemical device according to claim 2, wherein the electrochemical device is a battery.

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