WO2018043411A1

WO2018043411A1 - Ultrasonic welding method for separators

Info

Publication number: WO2018043411A1
Application number: PCT/JP2017/030763
Authority: WO
Inventors: 祐輔沖; 篤哉石橋; 稲益　徳雄
Original assignee: リチウムエナジーアンドパワーゲゼルシャフトミットベシュレンクテルハフッングウントコンパニーコマンディトゲゼルシャフト; 株式会社Ｇｓユアサ
Priority date: 2016-08-29
Filing date: 2017-08-28
Publication date: 2018-03-08
Also published as: JP6843870B2; CN110114909A; JPWO2018043411A1; DE112017004334T5; CN110114909B

Abstract

The present invention addresses the problem of providing an ultrasonic welding method for separators, by which two separators each having a heat resistant layer can be welded together while the heat resistant layers are opposed to each other such that the strength of bonding therebetween is relatively high. The ultrasonic welding method for separators according to one aspect of the present invention comprises: supporting, by a support member, at least two separators each having a resin layer and a heat resistant layer formed on the resin layer such that the heat resistant layers are opposed to each other; and moving, relative to the at least two separators, a vibration member that ultrasonically vibrates upon contact, in a dot pattern, with the separators, while pressing the vibration member against the separators.

Description

Ultrasonic welding method of separator

The present invention relates to a method for ultrasonic welding of a separator.

For example, secondary batteries that can be charged and discharged are used in various devices such as mobile phones and electric vehicles. In recent years, with higher output and higher performance of these devices, a secondary battery having a smaller size and a larger electric capacity has been demanded.

Generally, a secondary battery is formed by alternately laminating a positive electrode plate having a positive electrode active material layer formed on a surface and a negative electrode plate having a negative electrode active material layer formed on a surface via an electrically insulating separator. . In order to increase the electric capacity per unit volume in such a secondary battery, it is effective to make the separator thinner. For this reason, the secondary battery which formed the separator with the resin film is put into practical use.

In a secondary battery, metal deposits (for example, lithium dendrite) generated by electrodeposition in the negative electrode may penetrate the separator and cause a short circuit between the positive electrode plate and the negative electrode plate. For this reason, by welding the outer edges of a pair of separators sandwiching the positive electrode plate or the negative electrode plate into a bag shape, it is possible to suppress the inclusion of metal species that generate metal ions that can generate precipitates in the electrolyte near the positive electrode plate. Or a structure that suppresses metal ions from coming into contact with the negative electrode and being electrodeposited may be employed.

Since the separator formed from a resin film is relatively weak against heat, when the electric capacity of the secondary battery is increased, the separator is damaged by heat, and the precipitate generated by electrodeposition penetrates the separator and the positive electrode plate. There is a risk of short-circuiting the negative electrode plate. For this reason, a secondary battery has been proposed in which a heat-resistant layer (inorganic layer) is formed on the surface of the separator that contacts the electrode plate to improve the heat resistance of the separator.

However, if a separator having a heat-resistant layer is put on the surface of the resin film and the heat-resistant layers are brought into contact with each other, the heat-resistant layer inhibits the welding of the resin film, so that the separator cannot be easily welded.

In JP 2013-143337 A, a separator layer made of a resin material is laminated through a heat-resistant layer, and a portion where an exterior material is laminated from both sides is sandwiched between a pressure excitation unit and a jig receiving unit. In a method of manufacturing a secondary battery that applies vibration while applying pressure, it is proposed that the heat-resistant layer is destroyed by forming convex portions on the pressure excitation part and the jig receiving part, and the separator layer resin is welded at the destruction part. Has been.

JP-A-2015-185372 uses a separator (ceramic separator) containing a molten material (polypropylene layer) and a heat-resistant material (ceramic layer) as a separator bonding method for an electric device (packed electrode plate), and an electrode (positive electrode) Alternatively, as a method of joining while cutting a ceramic separator having a negative electrode) sandwiched between ceramic layers facing each other, cutting a joining region of a ceramic separator facing through an electrode, and connecting a polypropylene layer of one joining region to another It has been proposed to move toward the polypropylene layer in the joining region and melt and join the polypropylene layers in the joining region.

JP 2013-143337 A Japanese Patent Laying-Open No. 2015-185372

In the method described in Japanese Patent Application Laid-Open No. 2013-143337, since convex portions are formed in the pressure excitation unit and the jig receiving unit, welding is performed intermittently, and it is difficult to increase the welding area as a whole. It is not easy to obtain a good bonding strength.

Further, in the method described in JP-A-2015-185372, polypropylene layers can be continuously welded to each other. However, since a relatively sharp cutting blade is used, it is difficult to increase the welding width of polypropylene. Therefore, it is still difficult to increase the welding area as a whole, and it is not easy to obtain sufficient bonding strength.

In view of such a situation, it is an object of the present invention to provide an ultrasonic welding method for a separator that can weld two separators having a heat-resistant layer with the heat-resistant layers facing each other and has a relatively high bonding strength. And

In the ultrasonic welding method for a separator according to one aspect of the present invention, at least two separators having a resin layer and a heat-resistant layer formed on the resin layer are supported by a support member with the heat-resistant layers facing each other. And a relative movement with respect to the separator while pressing a vibration member that abuts on the separator in a dot shape and vibrates ultrasonically against the at least two separators.

According to another aspect of the present invention, there is provided an ultrasonic welding method for a separator, wherein at least two separators having a resin layer and a heat-resistant layer formed on the resin layer are opposed to each other, and ultrasonic vibration is applied. Sandwiching the at least two separators between the vibrating member and the support member that supports the separators in a dotted manner, and moving the at least two separators relative to the vibration member and the support member Is provided.

The above-described ultrasonic welding method of the separator can weld the separator having the heat-resistant layer with the heat-resistant layers facing each other, and has relatively high bonding strength.

It is typical sectional drawing which shows the ultrasonic welding method of the separator of one Embodiment of this invention. It is a schematic plan view of the ultrasonic welding method of the separator of FIG. It is typical sectional drawing which shows the ultrasonic welding method of the separator different from FIG. 1 of this invention. It is a typical fragmentary sectional side view of the ultrasonic welding method of the separator of FIG.

The present inventors have confirmed that in the conventional ultrasonic welding method using a linearly extending ultrasonic application member, it is difficult to sufficiently bond the separators with the heat-resistant layers of the two separators facing each other. The following hypothesis was made about the reason.

(Hypothesis 1)
In the ultrasonic wave application member extending linearly, energy is easily dispersed.

(Hypothesis 2)
When using a linearly extending ultrasonic application member, it is necessary to make the tip of the ultrasonic application member thin in order to concentrate the energy as much as possible, so that the welding width formed on the separator is narrow and sufficient. Bond strength is difficult to obtain.

(Hypothesis 3)
In the case of using a linearly extending ultrasonic wave application member, fragments of the heat-resistant layer destroyed by the ultrasonic wave application member are pushed out only to both sides of the separator with the line extending the ultrasonic wave application member as a boundary. Therefore, combined with the necessity of narrowing the tip for energy concentration, the welding width formed on the separator is narrowed, and it is difficult to obtain sufficient bonding strength.

Based on the above hypothesis, the present inventors use two vibration-resistant separators using a vibrating member that vibrates ultrasonically (for example, a vibrating member having a spherical tip) instead of a linearly extending member. An experiment for welding was performed. That is, a linear weld portion was formed by moving the welding point by moving the ultrasonic vibration member against the two separators while pressing the vibrating member against the two separators. Surprisingly, with this method, it was possible to sufficiently bond the separators with the heat resistant layers of the two separators facing each other without increasing the ultrasonic output.

In one embodiment of the present invention, at least two separators each having a resin layer and a heat-resistant layer formed on the resin layer are supported by a support member with the heat-resistant layers facing each other, and the separator has a dotted shape. The separator is ultrasonically welded to the separator by moving relative to the separator while pressing the vibrating member in contact with the at least two separators against each other.

In the ultrasonic welding method for the separator, at least two separators having a resin layer and a heat-resistant layer formed on the resin layer are placed on a support member with the heat-resistant layers facing each other, and are ultrasonically vibrated. By pressing a vibration member (ultrasonic vibrating indenter) against the at least two separators, sandwiching at least two separators between the vibration member and the support member, and applying ultrasonic vibration, the heat-resistant layer is destroyed and the resin is destroyed. The layers can be welded together.

Specifically, the ultrasonic welding method of the separator uses a vibrating member that comes into contact with the separator in a point-like manner, unlike an ultrasonic application member that extends in a linear shape, so that energy is concentrated in one place. Thus, it is considered that sufficient energy can be obtained to break the heat-resistant layer in a relatively large dot-like region and push the fragments of the heat-resistant layer to the outside in the plane direction to weld the resin layers together. Furthermore, the ultrasonic welding method of the separator can perform continuous welding by moving the vibrating member relative to the separator. For this reason, since the linear weld part which is continuous with a comparatively large width | variety can be formed, the joining strength of a separator can be made comparatively large.

The relative movement of the vibrating member may be performed by moving the absolute position of the vibrating member. Thus, by performing relative movement of the vibrating member by moving the absolute position of the vibrating member, the configuration of the apparatus can be relatively simplified, and productivity can be improved. Further, by moving the vibrating member, for example, the form of the welded portion formed on the two separators, such as a linear shape and a broken line shape, can be selected relatively freely.

The relative movement of the vibrating member may be performed while conveying the separator. Thus, productivity can be further improved by performing the relative movement of the vibration member while conveying the separator.

It is preferable that the radius of curvature of the contact portion of the vibration member with the separator is 0.5 mm or more. As described above, when the radius of curvature of the contact portion of the vibrating member to the separator is 0.5 mm or more, the width of the welded portion can be made relatively large, and the bonding strength between the separators can be more reliably increased. Can be improved. The “curvature radius” includes the point of contact with the separator, and the curvature radius of the cross section where the curvature radius of the contour line is the maximum in the cross section of the vibrating member perpendicular to the separator, and the contour line in the cross section orthogonal to the cross section. Mean the average value with the radius of curvature.

Relative movement of the vibrating member moves the vibrating member relative to the separator in a first direction, and moves the vibrating member relative to the separator in a second direction that intersects the first direction. It may include relative movement. The relative movement of the vibration member includes a relative movement in the first direction and a relative movement in the second direction, so that the planar shape is more complicated than two separators compared to a conventional linearly extending member. The welded portion can be formed. For example, it is relatively easy to dispose an electrode plate between two separators and form a welded portion along the contour of the electrode plate.

It is preferable that the vibration member is moved relative to the separator in the second direction while avoiding a separator weld formed when the vibration member is moved relative to the separator in the first direction. In this way, by performing the next welding while avoiding the place once welded, the productivity can be improved and a good welding state can be maintained.

It is preferable that an electrode plate is further disposed between the at least two separators, and a linear weld portion is formed along the contour of the electrode plate by relative movement of the vibration member. Thus, the electrode plate is further disposed between the at least two separators, and the electrode is formed by forming a linear weld portion along the contour of the electrode plate by relative movement of the vibration member. A bag-packed electrode in which the plate is covered with a bag-like separator can be efficiently produced.

Another aspect of the present invention is to provide at least two separators having a resin layer and a heat-resistant layer formed on the resin layer so that the heat-resistant layers face each other, a vibration member that vibrates ultrasonically, and the separator. An ultrasonic welding method for a separator, comprising sandwiching the at least two separators with a support member that is supported in a dotted manner, and moving the at least two separators relative to the vibration member and the support member. It is.

The ultrasonic welding method of the separator uses a support member that comes into contact with the separator in the form of dots, so that the heat concentrates in a relatively large dotted area by concentrating energy in one place, and fragments of the heat resistant layer It is considered that sufficient energy can be obtained to extrude the resin layer outward in the plane direction and weld the resin layers together. Furthermore, the ultrasonic welding method of the separator can perform continuous welding by moving the separator relative to the vibration member and the support member. For this reason, since the linear weld part which is continuous with a comparatively large width | variety can be formed, the joining strength of a separator can be made comparatively large.

The at least two separators may be cut by moving the at least two separators relative to the vibrating member. Thus, by cutting the at least two separators by moving the at least two separators relative to the vibrating member, the welding process and the cutting process are simultaneously performed to improve manufacturing efficiency. Can do.

The contact surface of the vibration member may be planar, and the support surface of the support member may be arcuate in a side view perpendicular to the relative movement direction of the separator. As described above, the contact surface of the vibration member is planar, and the support surface of the support member is arcuate in a side view perpendicular to the relative movement direction of the separator. The separator sandwiched between the two can be moved relatively smoothly.

Hereinafter, a method for ultrasonic welding of a separator according to an embodiment of the present invention will be described in detail with reference to the drawings as appropriate.

[Ultrasonic welding method of separator]
As shown in FIG. 1, the ultrasonic welding method of a separator according to an embodiment of the present invention heats at least two separators S having a resin layer 1 and a heat-resistant layer 2 formed on the resin layer 1. The layers 2 are opposed to each other and supported by a support member (anvil) A, and as shown in FIG. 2, a separator S while pressing a vibration member (horn) H that vibrates ultrasonically against the at least two separators S. Relative movement.

The ultrasonic welding method of the separator typically includes an electrode plate P for a storage element sandwiched between two separators S, and the two separators S are welded outside the electrode plate (positive electrode plate or negative electrode plate) P. Then, it can be adopted as one process for manufacturing a packaged electrode plate joined in an envelope shape. By using such a packaged electrode plate, it is possible to suppress the metal ions generated by the inclusion of foreign matter or the like from moving to the negative electrode on the positive electrode plate of the electricity storage element, and to prevent electrodeposition. Can be prevented.

<Separator>
The separator S may be supplied from a reel on which a long sheet is wound, and may be cut after the welding by the ultrasonic welding method. Further, the two separators S may be configured by folding one large sheet into two.

By continuously supplying the two separators S from the reel, a large number of packed electrode plates can be manufactured continuously and efficiently. The packaged electrode plate cuts the separator S by cutting the long sheet on which the welded portion C is formed by the ultrasonic welding method between the two welded portions C or at the center of the welded portion C. Can be obtained.

(Resin layer)
The resin layer 1 is formed from a porous resin film.

Examples of the main component of the resin layer 1 include polyethylene (PE), polypropylene (PP), ethylene-vinyl acetate copolymer, ethylene-methyl acrylate copolymer, ethylene-ethyl acrylate copolymer, and chlorinated polyethylene. Polyolefins such as polyolefin derivatives, ethylene-propylene copolymers, and polyesters such as polyethylene terephthalate and copolymerized polyesters can be used. Among these, as the main component of the resin layer 1, polyethylene and polypropylene excellent in electrolytic solution resistance, durability, and weldability are preferably used. The “main component” means a component having the largest mass content.

The lower limit of the average thickness of the resin layer 1 is preferably 5 μm and more preferably 10 μm. On the other hand, the upper limit of the average thickness of the resin layer 1 is preferably 50 μm, and more preferably 30 μm. By making the average thickness of the resin layer 1 equal to or greater than the lower limit, the separator S can be welded without the resin layer 1 breaking. Further, by setting the average thickness of the resin layer 1 to be equal to or less than the above upper limit, the capacity per unit volume of the power storage element can be sufficiently increased without unnecessarily increasing the thickness of the separator S.

(Heat resistant layer)
The heat-resistant layer 2 includes a large number of inorganic particles and a binder that connects the inorganic particles.

As the main component of the inorganic particles, for example, oxides such as alumina, silica, zirconia, titania, magnesia, ceria, yttria, zinc oxide, iron oxide, nitrides such as silicon nitride, titanium nitride, boron nitride, silicon carbide, carbonate Calcium, aluminum sulfate, aluminum hydroxide, potassium titanate, talc, kaolin clay, kaolinite, halloysite, pyrophyllite, montmorillonite, sericite, mica, amicite, bentonite, asbestos, zeolite, calcium silicate, magnesium silicate Etc. Among these, alumina, silica, and titania are particularly preferable as the main component of the inorganic particles of the heat-resistant layer 2.

The lower limit of the average particle diameter of the inorganic particles of the heat-resistant layer 2 is preferably 1 nm, and more preferably 7 nm. On the other hand, the upper limit of the average particle diameter of the inorganic particles is preferably 5 μm and more preferably 1 μm. By setting the average particle diameter of the inorganic particles to the above lower limit or more, the ratio of the binder in the heat-resistant layer 2 does not increase, and the heat-resistant layer 2 having sufficient heat resistance can be obtained. Moreover, the uniform heat resistant layer 2 can be easily formed by making the average particle diameter of inorganic particles below the upper limit. The “average particle diameter” is a value measured according to JIS-R1670 using a transmission electron microscope (TEM) or a scanning electron microscope (SEM).

Examples of the main component of the binder of the heat-resistant layer 2 include fluorine resins such as polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE), fluorine rubber such as vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene copolymer, Styrene-butadiene copolymer and its hydride, acrylonitrile-butadiene copolymer and its hydride, acrylonitrile-butadiene-styrene copolymer and its hydride, methacrylic acid ester-acrylic acid ester copolymer, styrene-acrylic acid Cellulose derivatives such as ester copolymers, synthetic rubbers such as acrylonitrile-acrylic acid ester copolymers, carboxymethylcellulose (CMC), hydroxyethylcellulose (HEC), ammonium salts of carboxymethylcellulose, etc. , Polyimide imides such as polyetherimide, polyamideimide, polyamide and precursors thereof (polyamic acid, etc.), ethylene-acrylic acid copolymers such as ethylene-ethyl acrylate copolymer, polyvinyl alcohol (PVA), polyvinyl butyral ( PVB), polyvinyl pyrrolidone (PVP), polyvinyl acetate, polyurethane, polyphenylene ether, polysulfone, polyether sulfone, polyphenylene sulfide, polyester and the like.

The lower limit of the average thickness of the heat-resistant layer 2 is preferably 0.5 μm and more preferably 1 μm. On the other hand, the upper limit of the average thickness of the heat-resistant layer 2 is preferably 10 μm, and more preferably 6 μm. By making the average thickness of the heat-resistant layer 2 equal to or more than the lower limit, the heat resistance of the separator S can be sufficiently improved. In addition, by setting the average thickness of the heat-resistant layer 2 to be equal to or less than the above upper limit, the capacity per volume of the power storage element can be sufficiently increased without unnecessarily increasing the thickness of the separator S.

(Electrode plate)
As the electrode plate P, the one obtained by laminating an active material layer on the surface of a metal foil is used.

As the material of the metal foil of the electrode plate P, for example, aluminum or the like can be used for the positive electrode, and for example, copper, iron, stainless steel, or the like can be used for the negative electrode.

As the active material of the electrode plate P, a material mainly composed of an oxide material such as LiCoO ₂ , LiNiO ₂ , LiMn ₂ O ₄ can be used in the case of the positive electrode, and graphite or the like can be used in the case of the negative electrode. Can be used.

(Support member)
The supporting member A may be any member as long as the top surface on which the separator S is placed is flat, has sufficient surface hardness, and strength.

When welding the two separators S while transporting them, the separators S may be slid on the support member A, but by feeding the support members A together with the separators S, the contact of the vibrating member H of the separators S It is possible to prevent unnecessary tension from acting on the contact area. Therefore, by moving the support member A together with the separator S, it is possible to prevent a decrease in the bonding strength of the separator S while continuously welding a plurality of pairs of separators S efficiently.

(Vibration member)
As the vibration member H, any member that contacts the separator S in a dot shape may be used. For example, the vibration member H may have a round bar shape and a hemispherical tip.

The lower limit of the radius of curvature of the contact portion of the vibration member H with the separator S is preferably 0.5 mm, and more preferably 1.0 mm. On the other hand, the upper limit of the radius of curvature of the contact portion of the vibration member H with the separator S is preferably 8 mm, and more preferably 15 mm. By setting the radius of curvature of the contact portion of the vibration member H to the separator S to be equal to or greater than the lower limit, a sufficient bonding strength can be obtained without reducing the width of the welded portion C of the two separators S. In addition, by setting the radius of curvature of the contact portion of the vibrating member H to the separator S to be equal to or less than the upper limit, the ultrasonic vibration is not dispersed over a wide range of the separator S, and the heat-resistant layer 2 can be efficiently destroyed. .

The vibration direction of the vibration member H is preferably inclined with respect to the surface of the separator S. Since the vibration direction of the vibration member is inclined with respect to the surface of the separator S, the heat-resistant layer 2 is destroyed by the ultrasonic vibration of the vibration member H, and the broken pieces of the heat-resistant layer 2 are ultrasonicated by the vibration member H. The resin layers 1 can be welded relatively easily by scraping them by vibration.

Further, since the vibration direction of the vibration member H is inclined with respect to the surface of the separator S, the clearance between the vibration member H and the support member A at the time of manufacture (interval in a state in which no ultrasonic vibration occurs) Even if it is adjusted to be smaller than the moving width (twice the amplitude) of the tip of the vibration member H by ultrasonic vibration, the vibration member H and the support member A do not collide with each other. For this reason, since the vibration direction of the vibration member H is inclined with respect to the surface of the separator S, the energy of ultrasonic vibration of the vibration member H can be transmitted efficiently, so that less It is considered that the welded portion C having a large length and a high peel strength can be formed.

The lower limit of the tilt angle with respect to the surface of the separator S in the vibration direction of the vibration member H is preferably 5 °, and more preferably 10 °. On the other hand, the upper limit of the inclination angle of the vibrating member H with respect to the surface of the separator S in the vibration direction is preferably 70 °, and more preferably 60 °. By setting the inclination angle of the vibration direction of the vibration member H with respect to the surface of the separator S to be equal to or greater than the lower limit, it is possible to efficiently apply ultrasonic vibration to the heat resistant layer 2 and efficiently destroy the heat resistant layer 2. A sufficient bonding strength can be obtained. In addition, by setting the inclination angle of the vibration member H in the vibration direction with respect to the surface of the separator S to be equal to or less than the upper limit, the resin layers 1 can be efficiently welded together by pushing away the broken pieces of the heat-resistant layer 2. , Can improve the efficiency.

In order to realize such vibration, as shown in FIG. 1, a rod-shaped vibrating member H that abuts against the separator S at the tip and ultrasonically vibrates in the axial direction is used. It is good to arrange inclining with respect to the surface of S.

The lower limit of the amplitude of the vibration member H is preferably 10 μm, and more preferably 27 μm. On the other hand, the upper limit of the amplitude of the vibration member H is preferably 80 μm, and more preferably 68 μm. By setting the amplitude of the vibrating member H to the lower limit or more, the heat-resistant layer 2 can be easily broken. Moreover, the damage of the resin layer 1 can be suppressed or an unnecessary decrease in energy efficiency can be suppressed by setting the amplitude of the vibration member H to the upper limit or less.

The frequency of ultrasonic vibration of the vibrating member H is preferably 10 kHz, and more preferably 20 kHz. On the other hand, the upper limit of the frequency of ultrasonic vibration of the vibrating member H is preferably 80 kHz, and more preferably 40 kHz. By setting the frequency of the ultrasonic vibration of the vibrating member H to be equal to or higher than the lower limit, damage to the resin layer 1 can be suppressed, the strength of the welded portion C of the separator S can be prevented from decreasing, and the separator S can be broken at the time of welding. Can be suppressed. Moreover, it can avoid that an apparatus becomes unnecessarily expensive by making the frequency of the ultrasonic vibration of the vibration member H below the said upper limit.

The lower limit of the pressure contact force (excluding the force acting by ultrasonic vibration) of the vibration member H with respect to the separator S is preferably 5N, and more preferably 10N. On the other hand, the upper limit of the pressure contact force of the vibrating member H with respect to the separator S is preferably 50N, and more preferably 30N. By setting the pressure contact force of the vibrating member H to the separator S to be equal to or higher than the lower limit, the heat-resistant layer 2 can be efficiently destroyed. Further, by setting the pressure contact force of the vibrating member H to the separator S to be equal to or less than the above upper limit, it is possible to suppress the decrease in the thickness of the welded portion C and the accompanying strength, and to break the separator S during the welding. Can be suppressed.

The moving direction of the vibrating member H preferably has an angle with respect to the vibrating direction of the vibrating member H in plan view. That is, it is preferable that the vibration of the vibration member H has a component in the width direction of the welded portion C to be formed. When the moving direction of the vibrating member H in plan view is different from the vibrating direction, the width of the welded portion C where the reciprocating movement of the pressure contact by the ultrasonic vibration of the vibrating member H is increased, and the heat-resistant layer destroyed. It is possible to efficiently weld the resin layers 1 to each other by scraping the two pieces into left and right.

The lower limit of the moving direction of the vibrating member H relative to the vibrating direction of the vibrating member H in plan view is preferably 30 °, and more preferably 40 °. By making the angle of the moving direction of the vibration member H with respect to the vibration direction of the vibration member H in a plan view equal to or greater than the lower limit, the broken pieces of the heat-resistant layer 2 can be efficiently pushed out of the welded portion C. It is possible to perform welding well or to obtain a sufficient bonding strength of the separator S. On the other hand, the upper limit of the angle in the moving direction of the vibration member H with respect to the vibration direction of the vibration member H in plan view is not particularly limited, and 90 ° is ideal considering only the weldability, but is shown in FIG. Thus, when the linear welded part C perpendicular to each other is formed on the two separators S, the moving direction D1 of the vibration member H with respect to the vibration direction of the vibration member H (the length direction of the vibration member H) in plan view. , The mechanism for changing the direction of the vibrating member H is not required by setting the angle of D2 to 45 °.

The vibration member H moves relative to the separator S by moving its absolute position while being ultrasonically vibrated while being in pressure contact with the upper surfaces of the two separators S placed on the support member A. A linear weld portion C is formed on the two separators S. For this reason, it is preferable that the vibration member H is held so as to be arbitrarily movable by a positioning drive mechanism formed from, for example, an articulated robot, an orthogonal coordinate system robot, or the like.

The relative movement of the vibration member H with respect to the separator S includes, for example, a movement in the first direction D1 and a movement in the second direction D2, as shown in FIG. Accordingly, the two separators S can be welded in a line along the contour of the electrode plate P while using the vibrating member H that comes into contact with the separator S in a point shape.

At this time, it is preferable that the vibration member H is relatively moved so as to form the welded portion C in the second direction D2 while avoiding the welded portion C in the first direction D1 formed earlier. That is, by preventing the vibration member H from pressing the same position of the separator S twice or more, the separator S of the welded portion C that has been previously formed is peeled off, or the separator S is broken at the welded portion C. Can be prevented.

[Other Embodiments]
The said embodiment does not limit the structure of this invention. Therefore, in the above-described embodiment, components of each part of the above-described embodiment can be omitted, replaced, or added based on the description and common general knowledge of the present specification, and they are all interpreted as belonging to the scope of the present invention. Should.

In the ultrasonic welding method for the separator, three or more separators may be welded. For example, the electrode laminate may be formed by alternately laminating a plurality of positive plates and a plurality of negative plates via separators, and collectively welding all separators outside the positive plates and the negative plates.

In the ultrasonic welding method, the vibration member may be relatively moved with respect to the separator by fixing the vibration member while being pressed against the separator and moving the support member on which the separator is loaded.

In the ultrasonic welding method, intermittent welds may be formed in a broken line shape, for example.

It may be cut while welding at least two separators by relative movement of the vibration member. In this case, it is preferable that the shape of the contact surface of the vibration member is substantially symmetrical to the left and right in the relative movement direction so that the separator can be cut at the center in the width direction of the formed welded portion.

In the above-described embodiment, two separators are sandwiched between the vibration member that vibrates ultrasonically and the support member, but the present invention is not limited to this form. The ultrasonic welding method of the separator according to the present invention includes at least two separators having a resin layer and a heat-resistant layer formed on the resin layer, the heat-resistant layers facing each other, a vibrating member that vibrates ultrasonically, Sandwiching the at least two separators between the separator and the support member that supports the separators in a dotted manner, and moving the at least two separators relative to the vibration member and the support member. Good.

The above ultrasonic welding method may be carried out by using, for example, an ultrasonic welding apparatus shown in FIGS. In this ultrasonic welding apparatus, the vibration member H1 that vibrates ultrasonically has a preferably flat contact surface that extends linearly in a side view perpendicular to the relative movement direction of the separator S. On the other hand, the support member A1 extends in an arc shape in a side view perpendicular to the relative movement direction of the separator S, and the width in the direction perpendicular to the relative movement direction of the separator S is sufficiently small. Abut. This ultrasonic welding apparatus can be suitably used for cutting the separator S while welding.

In the ultrasonic bonding method, at least two separators S are sandwiched between the contact surface of the vibration member H1 and the support surface of the support member A1, and the separator S is moved relative to the vibration member H1 and the support member A1. By doing so, two separators S can be welded along the direction of relative movement. In the ultrasonic welding apparatus of FIG. 3, the contact surface and the support surface come into contact with each other via the separator S, so that the energy of ultrasonic vibration is concentrated in one place, so that a relatively large dotted region is formed. It is considered that sufficient energy can be obtained to break the heat-resistant layer and extrude the heat-resistant layer fragments to weld the resin layers together.

As shown in the drawing, the support member A1 is formed in a convex shape that bulges toward the separator, and protrudes in a linear shape extending from the base B to the relative movement direction of the separator S, and a base B that ensures strength. , And a convex portion E that forms a support surface that contacts the separator S.

As a minimum of average width (substantially contact width with respect to separator S) of convex part E, 0.1 mm is preferred and 0.2 mm is more preferred. On the other hand, as an upper limit of the average width of the convex part E, 1 mm is preferable and 0.6 mm is more preferable. By setting the average width of the convex portions E to be equal to or greater than the lower limit, it is possible to sufficiently secure the width of the formed welded portion. Moreover, it can avoid that the contact area with respect to the separator S becomes large too much by making the average width of the convex part E below the said upper limit, and it can ensure welding.

The support member A1 comes into contact with the separator S substantially in a dot shape due to the small width of the projection E in particular. Since the contact point of the convex portion E with respect to the separator S may have a width of about 1 mm, the cross-sectional shape of the tip portion of the convex portion E is not particularly limited, and for example, a square shape, a trapezoidal shape, or a semicircular shape Various shapes such as can be adopted. As a particularly preferable example, the cross-sectional shape of the tip of the convex portion E can be a semicircular shape with a radius of about 0.2 mm.

Further, the outer shape of the convex portion E in the direction perpendicular to the relative movement direction of the separator S may be an arc shape or an elliptical arc shape. The lower limit of the radius of curvature at the contact position of the convex portion E with respect to the separator S in the direction perpendicular to the relative movement direction of the separator S is preferably 1 cm, more preferably 2 cm. As an upper limit of a curvature radius, 10 cm is preferable and 8 cm is more preferable. By setting the radius of curvature at the contact position of the convex portion E to be equal to or greater than the lower limit, the relative movement of the separator S can be facilitated. In addition, by setting the radius of curvature at the contact position of the convex portion E to be equal to or less than the upper limit, it is possible to avoid the support member A1 coming into linear contact with the separator S and disperse the pressure contact force, The welding of the separator S can be ensured.

The vibration direction of the vibration member H1 is preferably a direction perpendicular to the moving direction (plane direction) of the separator S. Thereby, the apparatus configuration becomes relatively simple and the relative movement of the separator S becomes easy. Moreover, when the vibration direction of the vibration member H1 is perpendicular to the separator S surface direction, the separator S can be cut at the center of the formed welded portion.

Note that the positional relationship between the vibration member H1 and the support member A1 can be arbitrarily changed. For example, the vibration member H1 may contact the lower surface of the separator S, and the support member A1 may contact the upper surface of the separator S.

Hereinafter, the present invention will be described in detail based on examples, but the present invention is not construed as being limited based on the description of the examples.

(Separator)
As a separator for ultrasonic welding, an average of 16 μm thick porous film formed of polypropylene as a main component is used as a resin layer, and alumina powder is coated on the surface of the resin layer using polyvinylidene fluoride as a binder. A separator having a heat-resistant layer having a thickness of 5 μm was prepared. Two separators were tested for ultrasonic welding with the heat-resistant layers facing each other in the manner described below. For comparison, a separator made of only the resin layer without a heat-resistant layer was prepared.

(Test No. 1)
Test No. 1, a spherical rod-shaped vibrating member having a radius of 3.25 mm was used, and the vibrating member was supported so that the axial direction was inclined by 20 ° with respect to the surface of the separator and pressed against the separator. By vibrating the vibrating member in the axial direction at a frequency of 39.5 kHz and moving the vibrating member in a direction perpendicular to the vibrating direction in plan view, two separators were welded. This test No. 1, the pressure contact load with respect to the separator was set to 16 N, the amplitude of the vibrating member was set to 80% of the maximum amplitude (67.7 μm), and the moving speed of the vibrating member was set to 500 mm / sec.

The two separators thus welded were observed with a microscope and the average thickness of the welded portion was measured to find that it was 31.2 μm. Further, a T-type peel test in accordance with JIS-K6854-3 (1999) was performed using a test piece obtained by cutting two welded separators into a width of 3 cm as an index of bonding strength between the two separators. As a result, test no. The peel strength at 1 was 1.3N. Moreover, when the peeling surface of the test piece after a peeling test was confirmed, it peeled in the welding part. Further, the sealability of the welded portions of the two separators was examined using a penetrant flaw detector, but the sealability was good.

(Test No. 2)
Test No. 2 except that the amplitude of the vibrating member was set to 100% of the maximum amplitude. The same test as 1 was performed. This test No. In No. 2, the average thickness of the welded portions of the two separators that were welded was 32.6 μm, and the peel strength was 4.9 N. Moreover, when the peeling surface of the test piece after a peeling test was confirmed, it peeled in the welding part. Moreover, the test result of the sealing performance using the penetrant flaw detection agent was good.

(Test No. 3)
Test No. 3 except that a separator consisting only of a resin layer was used. The same test as 2 was performed. This test No. 3, the average thickness of the welded portions of the two separators that were welded was 37.1 μm, and the peel strength was 14.5 N. Moreover, the test piece after a peeling test peeled in the welding part. Moreover, the test result of the sealing performance using the penetrant flaw detection agent was good.

(Test No. 4)
Test No. 4 except that the moving speed of the vibrating member was 250 mm / sec. The same test as 2 was performed. This test No. In No. 4, the average thickness of the welded portions of the two welded separators was 17.1 μm, and the peel strength was 10.5 N. Moreover, the test piece after a peeling test peeled in the welding part. Moreover, the test result of the sealing performance using the penetrant flaw detection agent was good.

(Test No. 5)
Test No. No. 5 except that the pressure contact load of the vibrating member was 18N. The same test as 2 was performed. This test No. 5, the average thickness of the welded portions of the two separators that were welded was 28.2 μm, and the peel strength was 5.9 N. Moreover, the test piece after a peeling test peeled in the welding part. Moreover, the test result of the sealing performance using the penetrant flaw detection agent was good.

(Test No. 6)
Test No. No. 6 except that the pressure contact load of the vibrating member was 24N. The same test as 2 was performed. This test No. In No. 6, two separators were welded and cut at the welded portion. The average width (total of both sides cut) of the two separators thus welded was 23.7 μm, and the peel strength (only one side cut) was 2.0 N. Further, the resin layer of the test piece after the peel test was broken. Moreover, the test result of the sealing performance using the penetrant flaw detection agent was good.

(Test No. 7)
Test No. 7 except that the moving speed of the vibrating member was 250 mm / sec. The same test as 1 was performed. This test No. In No. 7, the average width of the welded portions of the two separators that were welded was 23.7 μm, and the peel strength was 5.6 N. Further, the resin layer of the test piece after the peel test was broken. Moreover, the test result of the sealing performance using the penetrant flaw detection agent was good.

(Test No. 8)
Test No. 8 except that the amplitude of the vibrating member was set to 60% of the maximum amplitude and the moving speed of the vibrating member was set to 250 mm / sec. The same test as 1 was performed. This test No. In No. 8, two separators could be welded. The average thickness of the welded portions of the two separators thus welded was 20.0 μm, and the peel strength was 5.7 N. Further, the resin layer of the test piece after the peel test was broken. Moreover, the test result of the sealing performance using the penetrant flaw detection agent was good.

(Test No. 9)
Test No. 9 except that the amplitude of the vibrating member was set to 90% of the maximum amplitude and the moving speed of the vibrating member was set to 250 mm / sec. The same test as 1 was performed. This test No. In No. 9, two separators could be welded. The average thickness of the welded portions of the two separators thus welded was 25.2 μm, and the peel strength was 18.2N.

(Test No. 10)
Test No. No. 10 was used for welding by using a vibrating member linearly contacting the separator, setting the pressure contact load of the vibrating member to 200 N, setting the frequency of the vibrating member to 90% of the maximum amplitude (49 μm) at a frequency of 30 kHz. This test No. In No. 10, two separators could be barely welded. However, the peel strength of the two separators thus welded could not be measured because they were peeled off during handling. Further, the resin layer of the test piece after the peel test was broken. Moreover, the test result of the sealing performance using the penetrant flaw detection agent was a seal failure.

The test No. The conditions and results for 1 to 10 are shown in the following Tables 1 and 2. As an evaluation of the welded state, “A” indicates that two separators are welded, “B” indicates that two separators are welded and cut at the welded portion, and “C”. Indicates that the two separators were not welded.

As described above, even if a separator having a heat-resistant layer is disposed so that the heat-resistant layers are opposed to each other, the heat-resistant layer can be moved by relatively moving while pressing the vibration member that abuts against the separator in a dotted shape and ultrasonically vibrates. It was confirmed that the resin layers can be welded by breaking the layers. It was also confirmed that by adjusting the pressure contact load, amplitude, and moving speed of the vibration member, it was possible to perform welding with relatively high bonding strength or to cut while welding two separators.

The method for welding a separator according to the present invention can be suitably used for producing a packaged electrode plate.

DESCRIPTION OF SYMBOLS 1 Resin layer 2 Heat resistant layer A, A1 Support member B Base C Welding part D1 1st direction D2 2nd direction E Convex part H, H1 Vibration member P Electrode plate S Separator

Claims

Supporting at least two separators having a resin layer and a heat-resistant layer formed on the resin layer with a support member with the heat-resistant layers facing each other, and contacting the separators in a dotted manner with ultrasonic vibration An ultrasonic welding method for a separator, comprising: moving the vibrating member against the separator while pressing the vibrating member against the at least two separators.
The ultrasonic welding method of the separator according to claim 1, wherein the relative movement of the vibrating member is performed by moving the absolute position of the vibrating member.
3. The ultrasonic welding method according to claim 2, wherein the absolute position of the vibration member is moved while the separator is conveyed.
The ultrasonic welding method according to claim 1, 2 or 3, wherein a radius of curvature of a contact portion of the vibrating member with the separator is 0.5 mm or more.
The relative movement of the vibrating member is
Relative movement of the vibration member with respect to the separator in a first direction, and relative movement of the vibration member with respect to the separator in a second direction intersecting the first direction. The ultrasonic welding method according to any one of claims 1 to 4.
6. The vibration member is moved relative to the separator in the second direction while avoiding a separator weld formed when the vibration member is moved relative to the separator in the first direction. The ultrasonic welding method described in 1.
Further comprising disposing an electrode plate between the at least two separators;
The ultrasonic welding method according to claim 1, wherein a linear weld portion is formed along the contour of the electrode plate by relative movement of the vibration member.
The ultrasonic welding method according to any one of claims 1 to 7, wherein the at least two separators are cut by relative movement of the vibration member.
Making the at least two separators having a resin layer and a heat-resistant layer formed on the resin layer face each other,
Sandwiching the at least two separators between a vibration member that vibrates ultrasonically and a support member that supports the separators in a dot-like manner; and relative to the vibration member and the support member the at least two separators A separator ultrasonic welding method comprising: moving the separator.
The ultrasonic welding method according to claim 9, wherein the at least two separators are cut by moving the at least two separators relative to the vibrating member.
The ultrasonic welding method according to claim 9 or 10, wherein the contact surface of the vibration member is planar, and the support surface of the support member is arcuate in a side view perpendicular to the relative movement direction of the separator. .