KR101032443B1 - Separator for electronic components and production method therefor - Google Patents

Abstract

The present invention provides a separator for an electronic component and a method of manufacturing the same, which are both thin films and excellent in all of heat shrinkage prevention, mechanical strength and ion conductivity. The said separator for electronic components consists of a laminated body which has an air permeable base material and a polyolefin porous film. It is preferable that the said base material and the said polyolefin porous membrane are adhere | attached with an adhesive agent. It is preferable that the said adhesive agent contains a filler particle, when the said base material and the said polyolefin porous membrane are adhere | attached with an adhesive agent.

Separator, porous membrane made of polyolefin, adhesive, filler particles, secondary battery

Description

Separators for electronic components and manufacturing method therefor {SEPARATOR FOR ELECTRONIC COMPONENTS AND PRODUCTION METHOD THEREFOR}

1 shows an embodiment of the separator for an electronic component of the present invention, (a) is a cross-sectional view showing a separator for an electronic component whose substrate is a nonwoven fabric, and (b) is a separator for an electronic component whose substrate is a microporous film. It is sectional drawing which shows.

It is a figure explaining a microporous film, (a) is a top view, (b) is sectional drawing of A-A '.

It is sectional drawing which shows another Example of the separator for electronic components of this invention.

* Description of the main parts of the drawing *

1: Separator (separator for electronic component) 10: Laminated body

11: Base material 11a: Resin film

11b: Through-hole 12: Polyolefin porous membrane

13: adhesive 14 filler particle

The present invention relates to a separator used in electronic components such as a lithium ion secondary battery, a polymer lithium secondary battery, an aluminum electrolytic capacitor, an electric double layer capacitor, and a redox capacitor, and a manufacturing method thereof.

In electronic components such as a lithium ion secondary battery, a polymer lithium secondary battery, an aluminum electrolytic capacitor, an electric double layer capacitor, and a redox capacitor, an electrolyte solution is impregnated into an electrode body including a pair of electrodes and a separator. They are used in various electrical and electronic devices for industrial or public use.

In order to improve the performance of electrical and electronic devices, higher capacities and higher functionalities of electronic components are inevitable, and therefore, improvement of separators is required. For example, in order to cope with high capacity of electronic components, a separator having heat resistance, mechanical strength, and dimensional stability that can withstand abnormal heat generation, such as self-heating during charging and discharging or abnormal charging, is required. Moreover, in order to improve the high functionalization of electronic components, especially the rapid charge / discharge characteristic and the high output characteristic, the separator which has become thin and improved uniformity is further required.

For the purpose of satisfying such a demand, for example, "International Publication No. 01/67536 pamphlet" forms through-holes with a needle or a laser in a highly permeable microporous film (stretched film) produced by stretching polyolefin. It has been proposed to use a separator having a higher air permeability as a separator.

However, the separator described in "International Publication No. 01/67536 pamphlet" has high air permeability, thereby increasing the storage retention and ion conductivity of the electrolyte solution, and the mechanical strength is inferior because of the large diameter of the through hole formed by the needle or laser. Therefore, it may break at the time of manufacture or use, and a positive electrode and a negative electrode may directly contact and short-circuit. In particular, a minute projection of several micrometers is formed on the electrode surface of a lithium ion secondary battery or a polymer lithium secondary battery, and it is easy to break a separator, and a minute short circuit is easy to occur. When the separator is broken, the performance of the electronic component may be degraded because the ion movement or electron movement is concentrated at the broken portion.

In addition, when through-holes with a large diameter are formed, such as the separator described in "International Publication No. 01/67536", the electrodes are easily contracted in the meltdown temperature range above the shutdown temperature, so that the electrodes directly contact each other when the temperature is high. Easier

It is conceivable to lower the porosity of the separator as a method of securing heat shrinkage prevention property and mechanical strength in the state of a thin film. In this case, however, the internal resistance is increased and the ion conductivity is lowered, so that the demand for high functionalization cannot be satisfied.

The present invention provides a separator for an electronic component and a method for manufacturing the same, which are both thin films and excellent in heat shrinkage prevention property, mechanical strength, and ion conductivity.

The separator for electronic components of this invention consists of a laminated body which has a base material which has air permeability, and a polyolefin porous film.

The material of the substrate may be one selected from polyethylene telephthalate, polyarylate, polybutylene telephthalate, polyamide, polyamideimide, polytetrafluoroethylene, polyimide, polyethylene naphthalate, and polyphenylene sulfide. have.

The substrate may be a nonwoven fabric or a microporous film.

The polyolefin can be polyethylene and / or polypropylene.

The substrate and the polyolefin porous membrane may be bonded by an adhesive.

The adhesive may contain a component dissolved in the electrolyte solution constituting the electronic component.

Moreover, the said adhesive agent may contain resin which forms a porous structure.

The resin forming the porous structure may be polyvinylidene fluoride, polyacrylonitrile, polymethyl methacrylate, polyethylene terephthalate, polybutylene terephthalate, polyamide, polyamideimide, polytetrafluoroethylene, polyimide, One selected from polyethylene naphthalate, polyphenylene sulfide, and polyvinyl alcohol.

The adhesive may contain filler particles.

The separator for an electronic component of the present invention can be used for an electronic component selected from a lithium ion secondary battery, a polymer lithium battery, an aluminum electrolytic capacitor, an electric double layer capacitor, and a redox capacitor.

In the method for manufacturing a separator for an electronic component according to an embodiment of the present invention, a coating liquid containing an adhesive is applied onto at least one surface of a porous substrate and a polyolefin porous membrane having air permeability, and the substrate and the polyolefin are coated with the coating liquid. The porous membrane is overlapped and dried to be bonded.

According to another aspect of the present invention, there is provided a method for producing a separator for electronic components, wherein a solid adhesive is disposed on at least one surface of a porous membrane and a porous polyolefin membrane, and the substrate and the polyolefin are formed by the adhesive. The porous membrane is laminated and bonded.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

(Separator for Electronic Components)

An embodiment of the electronic component separator of the present invention (hereinafter, abbreviated as separator) will be described.

The separator of a present Example is shown to FIG. 1 (a) and (b). This separator 1 is a laminated body 10 to which the base material 11 and the porous polyolefin film 12 adhere | attached by the adhesive agent 13 containing resin which forms a porous structure. The said adhesive 13 is arrange | positioned inside the said base material 11, ie, the side which contact | connects the polyolefin porous membrane 12. As shown in FIG. In the separator 1, filler particles 14 are contained in the adhesive 13.

[materials]

The substrate 11 constituting the separator 1 may have air gaps formed therein. Here, air permeability means that the air permeability measured by the Garay type air permeability measuring apparatus which is description of JIS P # 8117 is 100 second / 100 ml or less.

Moreover, it is preferable that it is 20 to 90%, and, as for the ratio (porosity) of the space | gap of the base material 11, 30 to 80% is more preferable. When the ratio of the voids in the substrate 11 is 20% or more, the decrease in ion conductivity can be suppressed. If it is 90% or less, preferable mechanical strength can be maintained and a short circuit between electrodes can be prevented.

However, "porosity" in the present specification indicates the degree of porosity and is a value obtained from Equation 1 below from basis weight M (g / cm 2), thickness T (µm) and density D (g / cm 3). .

Porosity (%) = [1- (M / T) / D] × 100

As the base material 11, at least 1 sort (s) chosen from a nonwoven fabric, a woven fabric, a mesh, and a microporous film can be used. However, the base material in the example of FIG. 1 (a) is a nonwoven fabric of 1 sheet, and the base material in FIG. 1 (b) is a microporous film of 1 sheet.

Among these materials constituting the base material 11, a nonwoven fabric or a microporous film that can further improve both the heat shrinkage prevention property, the mechanical strength, and the ion conductivity of the separator 1 is preferable.

Here, the microporous film is a film in which a plurality of through holes 11b are formed in the resin film 11a (see FIGS. 2A and 2B).

The microporous film can be obtained, for example, by forming a plurality of through holes 11b in a stretched resin film 11a with a needle, a laser, or the like.

In the microporous film, the through hole 11b is preferably formed in the direction perpendicular to the surface 11c. In particular, when the microporous film is used for a lithium ion secondary battery or the like, the movement of ions is smooth and the internal resistance of the battery is lowered.

As for the average diameter of the through-hole 11b, 0.1-100 micrometers is preferable. If the average diameter of the through hole 11b is 0.1 µm or more, the ion conductivity is less likely to decrease. If the average diameter of the through hole 11b is 100 µm or less, the mechanical strength is improved, thereby reducing the possibility of short circuit. In addition, when the adhesive agent 13 contains the filler particle 14 like this embodiment, it is preferable to select the diameter of the through-hole 11b suitably according to the primary average particle diameter of the filler particle 14. As shown in FIG.

It is preferable that it is 0.01-100 micrometers on average, and, as for the shortest distance between the adjacent through-holes 11b in a microporous film, it is more preferable that it is 0.1-50 micrometers. If the average of the shortest distances is 0.01 µm or more, the mechanical strength of the microporous film can be sufficiently maintained, and the possibility of breaking at the time of winding decreases. If it is 100 micrometers or less, even if the diameter of the through hole 11b is small while having sufficient mechanical strength, ion conductivity will not fall.

In this invention, the average of the average diameter of the through-hole 11b and the shortest distance between the adjacent through-holes 11b is the value calculated as follows.

That is, first, the through holes 11b of the microporous film are observed with an electron microscope, and 100 through holes 11b are randomly selected. Then, the diameters of these through holes 11b are measured, the average value is calculated, and the average diameter is obtained.

However, the "average diameter" in this specification is a diameter by the bubble point method, and is a numerical value calculated | required using the polymeter made from Seika Industries.

Further, after randomly selecting 100 through-holes 11b as described above, the shortest distance between the through-holes 11b adjacent to each of the through-holes 11b is measured and the average value is calculated to calculate the average value between the adjacent through-holes 11b. Find the average of the shortest distances.

The substrate 11 may be composed of only one sheet selected from a nonwoven fabric, a woven fabric, a mesh, and a microporous film. However, a short circuit between electrodes caused by a lack of performance when assembled to an electronic component, specifically, mechanical strength and mechanical strength In consideration of the occurrence and the productivity, it is preferable that the laminate be stacked in two to four sheets. If more than four laminates are used, not only cost increase in internal resistance, impedance and production, but also thin film cannot be realized.

What is necessary is just to determine the film thickness of the base material 11 suitably according to the use of the separator 1. For example, a lithium ion secondary battery, a polymer lithium secondary battery, an aluminum electrolytic capacitor, or an electric double layer capacitor may thicken the electrode in order to achieve high capacity, but the thickness of the electrode may be increased by thinning the separator 1. Can be offset. In that case, 30 micrometers or less are preferable and, as for the film thickness of the separator 1, it is more preferable that it is 20 micrometers or less. If the film thickness is 30 µm or less, an increase in impedance can be suppressed without inhibiting ion migration.

However, when it is necessary to hold | maintain large amount of electrolyte solution, such as when applying to electronic components, such as an electric double layer capacitor, it is preferable to make thickness as thick as possible.

Although it does not restrict | limit especially as a material of the base material 11, Polyethylene telephthalate, polyarylate, polybutylene telephthalate, poly because it has a small heat shrinkage and is hard to melt | dissolve with respect to the organic solvent and ionic liquid used for electrolyte solution It is preferable that it is 1 type chosen from amidimide, polytetra fluoro ethylene, a polyimide, and polyethylene naphthalate. Especially, polyethylene terephthalate or polyarylate is more preferable. When polyethylene telephthalate or polyarylate is used, not only can the heat shrinkage of the separator 1 be further reduced, but also further suppress dissolution during overcharging and overheating, and further prevent short circuit due to contact between electrodes. can do.

[Polyolefin porous membrane]

The polyolefin porous membrane 12 is made of polyolefin and has uniformly several communication holes passing from one surface to the other surface. Since the polyolefin porous membrane 12 is not soluble in the electrolyte solution and is porous and has communication holes, the electrolyte solution can be stored and maintained. And the ion in electrolyte solution can be moved smoothly. In addition, it is possible to prevent the chemical reaction runaway when overheating due to overcharging or when the battery is overheated.

As a polyolefin, polyethylene, an ethylene-alpha-olefin copolymer, polypropylene, etc. are mentioned, for example. As polyethylene, a low density polyethylene, a high density polyethylene, etc. are mentioned, for example. Examples of propylene include homo polypropylene, polypropylene block copolymers, polypropylene random copolymers, and the like. Among these, polyethylene and / or polypropylene are preferable. In the case where the polyolefin is polyethylene and / or polypropylene, the insulating property between the electrodes is caused because the porous membrane dissolves and the hole is depressed in the temperature range (about 100 to 160 ° C.) where the electrochemical reaction is congested in electronic components such as a lithium ion secondary battery. It becomes high and can suppress an electrochemical reaction. In other words, it exhibits a shutdown function. And polyethylene is more preferable from the viewpoint of the wettability of the electrolyte solution or shutdown property. Especially, a high density polyethylene is especially preferable from a viewpoint of mechanical strength.

When polyolefin is polyethylene and polypropylene, it is preferable that the polyolefin porous membrane is a laminated porous membrane in which the polyethylene porous membrane and the polypropylene porous membrane were laminated | stacked.

It is preferable that it is 40 to 80%, and, as for the porosity of the polyolefin porous membrane 12, it is more preferable that it is 50 to 70%. If the porosity is 40% or more, sufficient ion conductivity can be maintained, and if it is 80% or less, the strength does not decrease and tends not to shrink.

It is preferable that the average diameter of the polyolefin porous membrane 12 is 0.01-1 micrometer. If the average diameter is 0.01 µm or more, the impregnability of the electrolyte solution is not lowered and preferable ion conductivity can be maintained. Moreover, when it is 1 micrometer or less, generation | occurrence | production of an internal short circuit can be prevented.

As thickness of the polyolefin porous membrane 12, the thinnest thing possible from the viewpoint of thinning of an electronic component is preferable, It is preferable that it is 5-30 micrometers specifically, It is more preferable that it is 10-20 micrometers. If the thickness of the polyolefin porous membrane 12 is 5 micrometers or more, preferable mechanical strength can be maintained and handling is also favorable. In consideration of thinning, the electronic component is preferably 30 μm or less.

The polyolefin porous membrane 12 is obtained by, for example, film forming a polyolefin by dissolution extrusion, then stretching the obtained film and forming a large number of minute cracks inside the film. Moreover, it is also obtained by adding fine particles etc. eluted to a solvent in advance to polyolefin, and film-forming by melt extrusion, and eluting fine particles with a solvent.

[glue]

The adhesive 13 is not particularly limited as long as the adhesive 13 has adhesiveness, but preferably contains a component dissolved in an electrolyte solution constituting the electronic component. Among the electronic components, particularly in lithium ion batteries, the separator shrinks when the temperature exceeds the operating temperature range, and the electrodes may directly contact and short-circuit. However, when the adhesive 13 contains a component that is dissolved in the electrolyte, the adhesive is dissolved in the electrolyte and the substrate 11 and the porous polyolefin film 12 are easily peeled off. As a result, although the polyolefin porous membrane 12 shrinks, the contraction of the substrate 11 due to the shrinkage of the polyolefin porous membrane 12 can be prevented, so that a short circuit between the electrodes can be prevented. Polyvinylidene fluoride is mentioned as a component melt | dissolved in electrolyte solution.

Moreover, it is preferable that the adhesive agent 13 contains resin which forms a porous structure. Such resins are not particularly limited, but polyvinylidene fluoride, polyacrylonitrile, polymethyl methacrylate, polyethylene terephthalate, polybutylene terephthalate, polyamide, polyamideimide, and polytetrafluoro fluoride have high electrical insulation properties. 1 type selected from ethylene, polyimide, polyethylene naphthalate, polyphenylene sulfide, and polyvinyl alcohol is preferable. These resins are appropriately selected according to the heat resistance, dimensional stability, and mechanical strength that the separator 1 requires. Among these resins, polyvinylidene fluoride is more preferable because of its excellent affinity with the electrolyte solution.

It is preferable that it is 0.1-15 micrometers, and, as for the average diameter of a porous structure, it is more preferable that it is 0.5-5 micrometers. If the average diameter of the pores is 0.1 µm or more, even when the filler particles 14 are contained as in the present embodiment, there is little possibility that the filler particles 14 will be secondary agglomerated very firmly, and the ion conductivity will not be reduced. On the other hand, if the thickness is 15 µm or less, the mechanical strength can be maintained even at room temperature when using a thin film, thereby preventing short circuits between the electrodes.

Moreover, it is preferable that the adhesive agent 13 contains a filler particle. Specific examples of the filler particles 14 include electrically insulating inorganic particles such as natural silica, synthetic silica, alumina, titanium oxide, and glass, and polytetrafluoroethylene, crosslinked acrylic, benzogamine, crosslinked polyurethane, crosslinked styrene, And organic particles such as melamine. Among these, it is preferable that it is a material which is hard to melt | dissolve or gelatinize in the electrolyte solution which comprises an electronic component from the point which can block the hole of the base material 11, and can suppress the performance fall of an electronic component. Moreover, in order to prevent the internal short circuit by the contact of the filler particles 14, it is preferable that it is electrically insulating. Specifically, electrically insulating inorganic particles or polytetrafluoroethylene particles having excellent chemical resistance, heat resistance, and dispersibility are preferable.

There is no restriction | limiting in particular as a shape of the filler particle 14, Any of an amorphous filler, a plate-shaped filler, a needle-shaped filler, or a spherical filler may be sufficient, but a spherical filler is preferable at the point which can disperse | distribute uniformly inside a porous structure.

The content of the filler particles 14 is preferably 50 g / m 2 or less, and more preferably 30 g / m 2 or less, based on the area of the separator 1. When the content of the filler particles 14 is 50 g / m 2 or less, the separator 1 does not become too thick and does not inhibit ion migration, so that a good impedance can be maintained.

The adhesive 13 is preferably a resin which forms a porous structure as described above. However, if the adhesive 13 is electrochemically stable without clogging the pores of the substrate 11 and the polyolefin porous membrane 12, the adhesive can not form a porous structure. It doesn't matter. However, in the case where the adhesive 13 is a resin that does not form a porous structure, it is preferable to apply a thin coating liquid containing the adhesive 13 so that the pores of the substrate 11 and the porous polyolefin membrane 12 are not blocked. Do. In order to apply | coat thinly, it is good to use the coating liquid with low density | concentration of the adhesive agent 13.

[Thickness of separator]

It is preferable that the thickness of the separator 1 is as thin as possible when the electronic component is other than the electric double layer capacitor. If the separator 1 is thin, the thickness of the entire electronic component can be reduced while increasing the capacity of the electronic component by increasing the electrode thickness. Specifically, the thickness of the separator 1 is preferably 40 µm or less, and more preferably 30 µm or less. When the thickness of the separator 1 is 40 µm or less, impedance is hardly increased without being inhibited by ion migration.

In the case where the electronic component is an electric double layer capacitor, the separator 1 is preferably thick in order to hold a large amount of the electrolyte solution.

(Method of manufacturing a separator)

[First Manufacturing Method]

Next, one Example of the 1st manufacturing method of the separator 1 is demonstrated. The 1st manufacturing method of a separator is what is called a wet lamination method. First, an adhesive agent is added to the solvent containing the good solvent with a high solubility with respect to this adhesive agent, and the poor solvent with a low solubility as needed, and prepare the coating liquid containing an adhesive agent. Here, when a poor solvent is added, an adhesive becomes easy to form a porous structure. In addition, when a poor solvent is not added, a non-porous structure is formed. Therefore, it is preferable to reduce the concentration of the adhesive to prevent blockage of the pores of the substrate and the pores of the polyolefin porous membrane.

In addition, the coating liquid preferably has a water content of 0.7% by mass or less and more preferably 0.5% by mass or less by measurement by the curl fischer method. If the amount of water in the coating liquid is 0.7% by mass or less, it is difficult to gel and the coating liquid can be stored for a long time. Moreover, the porous structure formed can be kept uniform, and there is no possibility of reducing the performance of an electronic component. Therefore, when using a hygroscopic thing as a solvent of a coating liquid, it is preferable to pay special attention to prevention of mixing of moisture.

Next, the said coating liquid is apply | coated on one surface of the polyolefin porous membrane. As a coating method of a coating liquid, the application | coating or casting method by the dip coating method, the spray coating method, the roll coating method, the doctor blade method, the gravure coating method, the screen printing method, etc. are mentioned, for example.

Subsequently, the substrate is overlaid on the applied coating liquid, dried to remove the solvent, and the substrate is bonded to the polyolefin porous membrane to obtain a separator.

The separator of high productivity can be obtained by the 1st manufacturing method of such a separator.

In said 1st manufacturing method, the polyolefin porous membrane may be mounted on the support body. When the polyolefin porous membrane is placed on the support, the support is peeled off after drying.

As a support body, resin films, such as polypropylene and polyethylene terephthalate, a glass plate, etc. are mentioned, for example. In addition, the support may be subjected to surface treatment such as a release treatment and a simple adhesion treatment. Among the said supports, the resin film which has flexibility is preferable. If the support is a resin film, the surface of the separator can be protected. And it can also wind up and store and convey a separator in the state laminated | stacked on the resin film.

Moreover, you may apply | coat a coating liquid on the surface of a base material, and may adhere | attach a base material and a polyolefin porous membrane.

As an example of the first manufacturing method, an example in which the base material is a nonwoven fabric is made of polyvinylidene fluoride which is a resin in which the adhesive forms a porous structure.

First, a polyvinylidene fluoride is disperse | distributed to the good solvent which can be melt | dissolved, and it melt | dissolves and prepares a coating liquid. Examples of the good solvent include N, N-dimethylacetamide, N, N-dimethyl formamide, 1-methyl-2-pyrrolidone, N, N-dimethylsulfoxide, and the like. As a dispersion and dissolution method, the method of using a commercially available stirrer is mentioned, for example.

However, polyvinylidene fluoride is easily dissolved at room temperature in N, N-dimethylacetamide, N, N-dimethyl formamide, 1-methyl-2-pyrrolidone, and N, N-dimethylsulfoxide, and the like. When using as a solvent, it does not need to heat especially in order to obtain a coating liquid.

Then, a poor solvent in which polyvinylidene fluoride does not dissolve may be added to the coating liquid. It is preferable to select a poor solvent having a higher boiling point than a good solvent. Dibutyl phthalate, ethylene glycol, diethylene glycol, glycerin, etc. are mentioned as an example of a poor solvent.

What is necessary is just to change suitably as a density | concentration of polyvinylidene fluoride in a coating liquid according to the required characteristic of the separator to obtain.

Next, a polyolefin porous membrane is placed on a support, and the coating liquid is applied onto the polyolefin porous membrane. Next, a nonwoven fabric is attached to the surface of the polyolefin porous membrane to which the coating liquid is applied, and a part of the coating liquid on the polyolefin porous membrane is transferred to the inside of the nonwoven fabric. And the solvent in a coating liquid is volatilized by drying. At this time, the solvent in the coating liquid may move around the resin, and the portion in which the solvent is turned may be a hole to form a porous structure. Then, the support is peeled off to obtain a separator.

[Second manufacturing method]

Next, one Example of the 2nd manufacturing method of the separator 1 is demonstrated. In the 2nd manufacturing method of the separator 1, a solid adhesive is first arrange | positioned at all or one part on one side of the polyolefin porous membrane. Here, it is preferable that the solid adhesive is lower than the melting point of the polyolefin constituting the polyolefin porous membrane.

Then, the substrates were overlaid with a solid adhesive therebetween, and the separators were sandwiched and bonded at a temperature higher than the melting point of the resin constituting the substrate while being lower than the melting point of the polyolefin porous membrane. Get

The separator of high productivity can be obtained also by the 2nd manufacturing method of such a separator.

In a 2nd manufacturing method, you may make it contain a solid adhesive previously in a base material, without placing a solid adhesive on a polyolefin porous membrane. Moreover, you may arrange | position a solid adhesive agent on a base material.

In the separator 1 of the above-described embodiment, the substrate 11 is laminated on the polyolefin porous membrane 12 by the adhesive 13, and the inside of the pores of the substrate 11 and the pores of the polyolefin fin membrane 12 Glue is filled up inside. Therefore, the polyolefin porous membrane 12 is reinforced and is excellent in heat shrink prevention property. Further, for the same reason, the mechanical strength is excellent, so that the breakage of the separator 1 is prevented and the short circuit caused by the direct contact between the electrodes is prevented.

In addition, the base material 11 laminated on the polyolefin porous membrane 12 not only has air permeability but also prevents the dense layer from being formed on the separator 1 because the adhesive 13 is a resin that forms a porous structure. Therefore, the storage retention of the electrolyte is good and the electrochemical characteristics and ion conductivity are excellent.

Moreover, in the separator 1, since the base material 11 and the polyolefin porous film 12 are adhered and integrated by the adhesive agent 13, winding error can be prevented at the time of manufacturing an electronic component, and it is excellent in handling. And the electrical resistance of the interface between the base material 11 and the porous polyolefin film 12 can be reduced, and the internal resistance of the separator 1 can be reduced.

In the separator 1, since the adhesive 13 contains the filler particles 14, it is possible to prevent the formation of a dense layer (skin layer), which is not a porous structure, and to further increase ion conductivity and electronic conductivity. Although the reason is not clear, when manufacturing the separator 1 by the wet lamination method, a solvent is unevenly distributed in the interface between the filler particles 14 uniformly dispersed in the coating liquid and the resin constituting the adhesive 13. It can be considered that this is because the porosity preferentially proceeds around the filler particles 14. In addition, since the filler particles 14 are uniformly dispersed in the surface and inside of the applied coating liquid, phase separation in the coating thickness direction tends to be uniform, and formation of a dense layer can be prevented. I guess.

The separator 1 of the above-described embodiment is used for an electronic component selected from among lithium ion secondary batteries, polymer lithium batteries, aluminum electrolytic capacitors, electric double layer capacitors, and redox capacitors in that the effects of the present invention are exhibited. It is preferable.

Here, a lithium ion secondary battery and a polymer lithium secondary battery have a positive electrode, a negative electrode, and a separator provided between them, and they are wound or laminated electrode bodies, and the electrode body is impregnated with a driving electrolyte. (Iii) and have a structure sealed by an aluminum case.

As a positive electrode, for example, a mixed liquid obtained by adding and mixing an active material, a binder such as a lithium-containing oxide and polyvinylidene fluoride in 1-methyl-2-pyrrolidone, onto an aluminum current collector The thing formed by apply | coating to this is mentioned.

As the negative electrode, for example, a mixed liquid obtained by adding and mixing a carbonaceous material capable of occluding and releasing lithium ions and a binder such as polyvinylidene fluoride in 1-methyl-2-pyrrolidone is made of copper. The thing formed by apply | coating on a collector is mentioned.

An aluminum electrolytic capacitor has an electrode body in which an anode foil and a cathode foil are wound or laminated through a separator, and the electrode body is impregnated with a driving electrolyte and sealed by an aluminum case and a sealing body.

As an anode foil, the aluminum foil etc. which formed the dielectric film by chemical conversion after etching are mentioned, for example.

As a cathode foil, the etched aluminum foil etc. are mentioned, for example.

In addition, from the positive electrode foil and the negative electrode foil, the positive electrode lead and the negative electrode lead penetrate through the sealing member and are drawn out to the outside.

An electric double layer capacitor has an electrode body in which an anode and a cathode are wound or laminated through a separator, and the electrode body is impregnated with a driving electrolyte and sealed by an aluminum case and an encapsulation body.

As a positive electrode and a negative electrode, what adhere | attached the mixture which mixed the activated carbon, the electrically conductive agent, and the binder on both surfaces of the electrical power collector which consists of aluminum sheets is mentioned.

In addition, in the positive electrode foil and the negative electrode foil, the positive electrode lead and the negative electrode lead pass through the sealing member and are drawn out to the outside.

The electronic component is excellent in both performance and reliability since the separator having excellent ion conductivity and mechanical strength is disposed.

However, the present invention is not limited to the above embodiment. For example, although the filler particle 14 is contained in the adhesive agent 13 in the above-mentioned embodiment, as shown in FIG. 3, a filler particle does not need to be contained in the adhesive agent 13. As shown in FIG. However, it is preferable to include the filler particle 14 in that an ion conductivity can be heightened further.

Moreover, in the above-mentioned embodiment, although the adhesive agent 13 is arrange | positioned at the polyolefin porous membrane 12 side inside the base material 11, the whole inside of the base material 11 and the hole of the polyolefin porous film 12 whole. It is okay if the contains adhesive. In that case, the smoothness of the surface of the separator 1 becomes high. When the smoothness of the surface of the separator 1 becomes high, the electrochemical reaction between the electrodes in contact with the separator 1 can be uniformized over the entire surface without concentrating on a specific location.

In addition, in this invention, it is not necessary to use an adhesive agent. For example, you may heat-dissolve a part of the base material 11, and the base material 11 and the polyolefin porous film 12 may be adhere | attached.

[Example]

Hereinafter, although the separator of this invention and its manufacturing method are demonstrated by an Example, this invention is not limited by these Examples.

(Example 1)

Polyvinylidene fluoride of 170 degreeC of melting | fusing point was melt | dissolved in N and N- dimethylacetamide (good solvent), and the coating liquid of 3 mass% of solid content concentration was prepared. Next, a high-density polyethylene stretched porous membrane (polyolefin porous membrane) having a porosity of 55% and a thickness of 10 µm was placed on a support made of polyethylene terephthalate. Next, the said coating liquid was apply | coated by the casting method on this polyolefin porous membrane. Subsequently, a polyethylene telephthalate nonwoven fabric having a porosity of 75% and a thickness of 13 µm was superimposed on the coated surface to evaporate the solvent in the coating liquid with heat, and the high density polyethylene stretched porous membrane and the polyethylene telephthalate nonwoven fabric were bonded to each other to form a laminate. At the same time the adhesive was porous. Then, the support body was peeled and removed from this laminated body and the separator with a thickness of 25 micrometers was obtained.

(Example 2)

As a polyolefin porous membrane, a high-density polyethylene-oriented porous membrane having a porosity of 50% and a thickness of 12 µm was used instead of a high-density polyethylene-oriented porous membrane having a porosity of 55% and a thickness of 10 µm. The porosity was 75% and the thickness was used as a substrate. A separator having a thickness of 26 µm was obtained in the same manner as in Example 1 except that a polyethylene telephthalate nonwoven fabric having a porosity of 70% and a thickness of 13 µm was used in place of the 13 µm polyethylene nonphthalate cloth.

(Example 3)

The polyvinylidene fluoride of melting | fusing point 170 degreeC was melt | dissolved in N, N- dimethylacetamide (good solvent), dibutyl phthalate (poor solvent) was added, and the coating liquid of 3 mass% of solid content concentration was prepared. Next, the laminated porous membrane which laminated | stacked the high-density polyethylene stretched porous film of 60% of porosity and 15 micrometers in thickness, and the stretched porous film made of homo polypropylene on the support which consists of polyethylene telephthalate was mounted. And the said coating liquid was apply | coated on the laminated porous membrane by the casting method. A polybutylene terephthalate nonwoven fabric having a porosity of 60% and a thickness of 15 µm was superimposed thereon, and the solvent in the coating liquid was evaporated by heat to bond the laminated porous membrane and the polybutylene telephthalate nonwoven fabric to obtain a laminate. The adhesive was porous. Then, the support body was peeled off from this laminated body and the separator with a thickness of 33 micrometers was obtained.

(Example 4)

As a polyolefin porous membrane, a porous porous membrane made of polyethylene having a porosity of 65% and a thickness of 13 µm was used instead of the laminated porous membrane, and a porosity of 40 was used instead of a polybutylene terephthalate nonwoven fabric having a porosity of 60% and a thickness of 15 µm as a substrate. A separator having a thickness of 22 µm was obtained in the same manner as in Example 3 except that the polyethylene porous phthalate microporous film having a% and a thickness of 6 µm was used.

(Example 5)

A porous membrane made of polyolefin was used as a porous membrane made of polyethylene having a porosity of 50% and a thickness of 10 μm in place of the laminated porous membrane, and a porosity of 50% instead of a polybutylene terephthalate nonwoven fabric having a porosity of 60% and a thickness of 15 μm as a substrate. A separator having a thickness of 24 μm was obtained in the same manner as in Example 3, except that the polyethylene porous phthalate microporous film having a% and a thickness of 12 μm was used.

(Example 6)

Polytetrafluoroethylene particles having a primary average particle diameter of 0.5 mu m after melting polyvinylidene fluoride having a melting point of 170 DEG C in N, N-dimethylacetamide (good solvent) and adding dibutyl phthalate (poor solvent). Was added to prepare a coating liquid having a solid content concentration of 3% by mass (filler particles in solid content were 50% by mass). Next, a polyethylene porous membrane having a porosity of 55% and a thickness of 12 µm was placed on a support made of polyethylene terephthalate, and the coating solution was applied onto the polyethylene porous membrane by the casting method. A polyethylene porous phthalate microporous film having a porosity of 75% and a thickness of 13 μm was superimposed thereon, and the solvent in the coating liquid was evaporated by heat to bond the polyethylene porous membrane and the polyethylene telephthalate microporous film to obtain a laminate. At the same time the adhesive was porous. Then, the support body was peeled off from this laminated body and the separator with a thickness of 27 micrometers was obtained.

(Example 7)

A separator having a thickness of 27 µm was prepared in the same manner as in Example 6 except that a polyethylene telephthalate nonwoven fabric having a porosity of 70% and a thickness of 12 µm was used instead of the polyethylene porous phthalate microporous film having a porosity of 75% and 13 µm. Got it.

(Example 8)

A polyethylene terephthalate nonwoven fabric having a porosity of 75% and a thickness of 13 μm (melting point of 220 ° C.) was sprayed with a dispersion (water is water) containing polyethylene particles having a particle diameter of 0.2 μm and a melting point of 80 ° C., and left at 50 ° C. ( V) dried. Next, a porous polyethylene film (melting point of 120 ° C.) having a porosity of 55% and a thickness of 12 μm was placed on a support made of polyethylene terephthalate. Next, the polyethylene porous membrane was superimposed so that the surface which disperse | distributed the said polyethylene terephthalate nonwoven fabric contacted. And it pressed by the hot press heated at 90 degreeC, and adhere | attached. After adhesion, the support was peeled off and removed to obtain a separator having a thickness of 26 µm.

(Example 9)

A separator having a thickness of 24 µm was obtained in the same manner as in Example 5 except that an aqueous solution of polyvinyl alcohol having a concentration of 2% by mass was used instead of the coating liquid containing polyvinylidene fluoride.

(Example 10)

The thickness was 30 in the same manner as in Example 5 except that a polyphenylene sulfide nonwoven fabric having a porosity of 65% and a thickness of 17 μm was used instead of the polyethylene porous phthalate microporous film having a porosity of 50% and a thickness of 12 μm. A micrometer separator was obtained.

(Example 11)

Dibutyl phthalate (poor solvent) was added to an N, N-dimethylacetamide (good solvent) solution in which polyimide having no substantial melting point was dissolved to prepare a coating solution having a solid content concentration of 3% by mass. Next, a polyethylene porous membrane having a porosity of 55% and a thickness of 10 µm was placed on a support made of polyethylene terephthalate, and the coating solution was applied onto the polyethylene porous membrane by the casting method. Then, a polyethylene telephthalate nonwoven fabric having a porosity of 65% and a thickness of 13 µm was superimposed thereon, and the solvent in the coating liquid was evaporated by heat to bond the polyethylene porous membrane and the polyethylene telephthalate nonwoven fabric to obtain a laminate, and at the same time, an adhesive agent. Was porous. Then, the support body was peeled off from this laminated body and the separator with a thickness of 25 micrometers was obtained.

(Example 12)

In the same manner as in Example 1 except that a polyarylate nonwoven fabric having a porosity of 65% and a thickness of 13 µm was used instead of a polyethylene telephthalate nonwoven fabric having a porosity of 75% and a thickness of 13 µm as the substrate having air permeability. A 25-micrometer separator was obtained.

(Comparative Example 1)

The polyethylene-stretched porous film of 20 micrometers in thickness generally used for a lithium ion secondary battery was used as a separator.

(Comparative Example 2)

A nonwoven separator made of cellulose pulp having a thickness of 30 μm, which is generally used for an electric double layer capacitor, was used as the separator.

(Comparative Example 3)

A polyethylene terephthalate nonwoven fabric having a porosity of 60% and a thickness of 13 µm was used as a separator.

(Comparative Example 4)

A polyethylene porous phthalate microporous film having a porosity of 40% and a thickness of 8 µm was used as a separator.

The characteristics were evaluated as follows with respect to the separator obtained by the said Examples 1-12 and Comparative Examples 1-4.

<Heat-resistant dimensional stability (heat shrinkage prevention) and peelability>

The separator of an Example and a comparative example was cut out and the square test piece of 5x5 cm was obtained. Subsequently, the test piece was immersed in a liquid of propylene carbonate, and then sandwiched between two glass plates 10 cm long by 10 cm wide by 5 mm thick, and then placed in a horizontal butt. And it left to stand in 150 degreeC, 200 degreeC, and 250 degreeC oven, respectively, for 1 hour, and measured the area by heat. Area retention ratio = (area after test / area before test: 25 cm 2) x 100 (%) was obtained, and this area retention was taken as an index of heat-resistant dimensional stability. However, the larger the area retention, the better the heat-resistant dimensional stability.

Moreover, as a result of simultaneously confirming the peelability of the polyolefin porous membrane and the substrate, the separator of Examples 1 to 12 peeled off the polyolefin porous membrane and the substrate after heating. In the case of peeling, the area retention ratio was calculated based on the larger area of the substrate or the polyolefin porous membrane. The results are shown in Table 1.

Area retention rate (%) Peelability (When peeled: ○) 150 ℃ 200 ℃ 250 ℃ 150 ℃ 200 ℃ 250 ℃ Example 1 100.0 90.1 89.1 ○ ○ ○ Example 2 100.0 92.0 90.4 ○ ○ ○ Example 3 100.0 91.6 90.6 ○ ○ ○ Example 4 100.0 93.7 92.0 ○ ○ ○ Example 5 100.0 92.9 90.8 ○ ○ ○ Example 6 100.0 97.0 95.5 ○ ○ ○ Example 7 100.0 96.6 94.4 ○ ○ ○ Example 8 100.0 95.5 93.8 ○ ○ ○ Example 9 100.0 97.3 95.0 ○ ○ ○ Example 10 100.0 94.1 91.7 ○ ○ ○ Example 11 100.0 96.3 94.5 ○ ○ ○ Example 12 100.0 100.0 100.0 ○ ○ ○ Comparative Example 1 45.1 10.3 7.6 - - - Comparative Example 2 95.1 83.2 80.1 - - - Comparative Example 3 100.0 91.0 88.1 - - - Comparative Example 4 100.0 92.7 90.0 - - -

The separator for electronic components in which the base material and the polyolefin porous film were laminated | stacked was excellent in heat shrink prevention property. In addition, since these separators shrink only the polyolefin porous membrane after heating and the base material and the polyolefin porous membrane were peeled off, it turned out that an internal short circuit does not generate | occur | produce in high temperature area | region. Therefore, in the separator of Examples 1-12, it turned out that the meltdown which arises from the short circuit of an electrode in the shutdown temperature range or more can be avoided.

On the other hand, the separator of the comparative example 1 only by the polyethylene-stretched porous film made by polyethylene, and the separator of the comparative example 2 only by the nonwoven fabric which consists of cellulose pulp are low in heat shrink prevention property, and did not have peelability. In particular, the separator of Comparative Example 1 was completely dissolved at 200 ° C, and thus could not be maintained in shape.

The separator of the comparative example 3 only with the polyethylene telephthalate nonwoven fabric, and the separator of the comparative example 4 only with the polyethylene telephthalate microporous film did not have peelability.

<Inner short circuit prevention property (mechanical strength)>

Two stainless plates (3 x 3 cm) were pressed so that the positive electrodes were in close contact with a potential difference of 80 V between the stainless electrodes with the separators (5 x 5 cm) of the Examples and Comparative Examples interposed therebetween. And the pressure at the time of short circuit (when the electrical resistance value became almost 0 kPa) was measured, and this was made into the short circuit pressure. The test was carried out five times to obtain an average value. The results are shown in Table 2. However, the higher the short-circuit pressure, the more excellent the internal short-circuit prevention property (it is hard to short-circuit).

Short circuit pressure (kg / ㎠) One 2 3 4 5 Average Example 1 339 335 339 345 331 338 Example 2 375 370 375 379 371 374 Example 3 356 355 348 349 350 352 Example 4 354 371 365 373 364 365 Example 5 376 381 376 373 380 377 Example 6 389 384 378 378 384 383 Example 7 367 365 367 363 369 366 Example 8 365 364 368 359 360 363 Example 9 390 393 397 389 387 391 Example 10 372 369 371 373 367 370 Example 11 381 377 371 390 383 380 Example 12 341 345 333 336 337 338 Comparative Example 1 Short circuit before applying pressure Comparative Example 2 151 112 125 138 110 127 Comparative Example 3 166 110 123 108 109 123 Comparative Example 4 211 223 237 201 224 219

As shown in Table 2, the separator for electronic components in which the base material and the porous film made of a polyolefin were laminated | stacked not only was excellent in internal short circuit prevention but also the variation was small.

On the other hand, in the separator of the comparative example 1 only of the polyethylene-stretched porous film, since it shrink | heat-shrinks at the time of high temperature heating, and the stainless electrodes directly contact, it short-circuited even if it did not pressurize.

The separator of Comparative Example 2 only of the nonwoven fabric made of cellulose pulp had low internal short circuit protection. Moreover, the separator of the comparative example 3 only by the polyethylene telephthalate nonwoven fabric and the comparative example 4 only by the polyethylene telephthalate microporous film had low internal short circuit prevention property.

<Ion conductivity>

Separator ion conductivity was measured by the alternating current impedance method. Specifically, the separators of Examples 1 to 12 and Comparative Examples 1 to 4 were vacuum-impregnated in an electrolyte solution in which (C ₂ H ₅ ) ₄ BF ₄ dissolved in propylene carbonate at a concentration of 1 mol / l, followed by The separator was put in and measured at 20 degreeC. At this time, the electrode for electric double layer capacitors manufactured by Takaraizumi Co., Ltd. was used for the electrode. The results are shown in Table 3.

Ionic conductivity
(S / cm) Example 1 8.0 × 10 ^-4 Example 2 7.9 x 10 ^-4 Example 3 7.7 × 10 ^-4 Example 4 7.4 x 10 ^-4 Example 5 7.0 × 10 ^-4 Example 6 8.1 x 10 ^-4 Example 7 7.5 × 10 ^-4 Example 8 6.6 × 10 ^-4 Example 9 7.2 x 10 ^-4 Example 10 7.8 × 10 ^-4 Example 11 7.5 × 10 ^-4 Example 12 8.1 x 10 ^-4 Comparative Example 1 2.1 x 10 ^-4 Comparative Example 2 3.9 × 10 ^-4 Comparative Example 3 ― Comparative Example 4 ―

As shown in Table 3, the separator of Examples 1-12 in which the base material and the polyolefin porous membrane were laminated | stacked was excellent in ion conductivity.

In contrast, the separator of Comparative Example 1 only of the polyethylene stretched porous film and the separator of Comparative Example 2 only of the nonwoven fabric made of cellulose pulp had low ion conductivity. In addition, the separator of the comparative example 3 only with the polyethylene telephthalate nonwoven fabric, and the separator of the comparative example 4 only with the polyethylene telephthalate microporous film generate | occur | produced the internal short circuit, and was unable to measure.

The separator for an electronic component of the present invention is excellent in both heat shrinkage prevention property, mechanical strength, and ion conductivity while being a thin film.

The material of the base material in the separator for electronic components of this invention is polyethylene terephthalate, polyarylate, polybutylene telephthalate, polyamide, polyamideimide, polytetrafluoroethylene, polyimide, polyethylene naphthalate, and If it is 1 type chosen from polyphenylene sulfide, heat shrinkage can be made smaller and the solubility to the organic solvent and ionic liquid used as electrolyte solution can be reduced.

If the substrate is a nonwoven fabric or a microporous film, the ion conductivity can be further increased.

If the polyolefin is polyethylene and / or polypropylene, a shutdown function can be exhibited.

When the base material and the porous membrane made of polyolefin are adhered as an adhesive, the operability at the time of assembling an electronic component improves.

When the said adhesive contains the component which melt | dissolves in the electrolyte solution which comprises an electronic component, the short circuit by the contact of electrodes can be prevented at the time of overcharge or overheating.

When the said adhesive contains resin which forms a porous structure, ion conductivity can be heightened more.

The resin forming the porous structure is polyvinylidene fluoride, polyacrylonitrile, polymethyl methacrylate, polyethylene terephthalate, polybutylene terephthalate, polyamide, polyamideimide, polytetrafluoroethylene, polyimide, The electrical insulation can be improved as long as it is one selected from polyethylene naphthalate, polyphenylene sulfide, and polyvinyl alcohol.

When the adhesive contains filler particles, the ion conductivity can be further increased.

The separator for electronic components of the present invention can be suitably used for electronic components such as lithium ion secondary batteries, polymer lithium secondary batteries, aluminum electrolytic capacitors, electric double layer capacitors, or redox capacitors.

According to the manufacturing method of the separator for electronic components of this invention, the separator for electronic components which is thin and excellent in mechanical strength and ion conductivity can be obtained with high productivity.

Claims (13)

It consists of a laminate having a substrate having an air permeability, an adhesive and a porous membrane made of polyolefin, The base material and the polyolefin porous membrane are bonded by the adhesive, The adhesive contains a component that dissolves in the electrolyte constituting the electronic component and a resin forming a porous structure, wherein the resin forming the porous structure is polyvinylidene fluoride, polyacrylonitrile, polymethyl methacrylate, polyethylene tele Phthalate, polybutylene telephthalate, polyamide, polyamideimide, polytetrafluoro ethylene, polyimide, polyethylene naphthalate, and polyphenylene sulfide, one selected from polyvinyl alcohol, The substrate is an electronic component separator, characterized in that the non-woven fabric or microporous film. The method of claim 1, The material of the said base material is 1 type selected from polyethylene telephthalate, polyarylate, polybutylene telephthalate, polyamide, polyamideimide, polytetrafluoroethylene, polyimide, polyethylene naphthalate, and polyphenylene sulfide. Separator for electronic components, characterized by the above-mentioned. delete The method of claim 1, A separator for an electronic component, wherein said polyolefin is polyethylene and / or polypropylene. delete delete delete delete delete The method of claim 1, The said adhesive agent contains filler particle, The separator for electronic components characterized by the above-mentioned. The method of claim 1, The separator for electronic components used for the electronic component selected from a lithium ion secondary battery, a polymer lithium secondary battery, an aluminum electrolytic capacitor, an electric double layer capacitor, and a redox capacitor. Applying a coating liquid containing an adhesive on at least one surface of a porous substrate and a porous porous membrane made of a polyolefin, and overlapping the substrate and the porous porous membrane made of a polyolefin with the coating liquid to dry and adhere, The adhesive contains a component that dissolves in the electrolyte constituting the electronic component and a resin forming a porous structure, wherein the resin forming the porous structure is polyvinylidene fluoride, polyacrylonitrile, polymethyl methacrylate, polyethylene tele Separators for electronic components, characterized in that one selected from phthalate, polybutylene telephthalate, polyamide, polyamideimide, polytetrafluoroethylene, polyimide, polyethylene naphthalate, and polyphenylene sulfide, polyvinyl alcohol Method of preparation. A solid adhesive is disposed on at least one surface of the substrate having the air permeability and the porous porous film made of polyolefin, and the adhesive is formed by overlapping the substrate and the porous film made of polyolefin by the adhesive, The adhesive contains a component that dissolves in the electrolyte constituting the electronic component and a resin forming a porous structure, wherein the resin forming the porous structure is polyvinylidene fluoride, polyacrylonitrile, polymethyl methacrylate, polyethylene tele Separators for electronic components, characterized in that one selected from phthalate, polybutylene telephthalate, polyamide, polyamideimide, polytetrafluoroethylene, polyimide, polyethylene naphthalate, and polyphenylene sulfide, polyvinyl alcohol Method of preparation.

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