WO2021153777A1

WO2021153777A1 - Tab lead for batteries

Info

Publication number: WO2021153777A1
Application number: PCT/JP2021/003376
Authority: WO
Inventors: 友多佳松村; 太郎藤田; 利紀吉羽; 和聡椎名; 貴章島田; 峻介岡本
Original assignee: 住友電気工業株式会社
Priority date: 2020-01-31
Filing date: 2021-01-29
Publication date: 2021-08-05
Also published as: KR20210134758A; CN113632312A; JPWO2021153777A1

Abstract

A tab lead for batteries, which is provided with a lead conductor and a resin layer that coats a heat-fused part in the lead conductor, wherein the resin layer has a conductor-adhesive layer arranged on the lead conductor side, an intermediate layer and a packaging-material-adhesive layer arranged on the opposite side to the conductor-adhesive layer side of the intermediate layer, the conductor-adhesive layer contains a polyolefin resin, the intermediate layer contains a crosslinked polyolefin resin, the packaging-material-adhesive layer contains a polyolefin resin, and the elastic modulus at 200°C is 0.1 MPa to 15 MPa inclusive.

Description

Battery tab lead

The present disclosure relates to battery tab leads.
This application claims priority based on Japanese Application No. 2020-014715 filed on January 31, 2020, and incorporates all the contents described in these Japanese applications.

As a lead wire used in a battery, a tab lead for a battery composed of a lead conductor connected to a positive electrode or a negative electrode of the battery and an insulating resin layer covering the lead conductor has been proposed.
Patent Document 1 describes a lead member (tab lead) in which a pair of insulating films are attached to both surfaces of a heat-sealed portion of a lead conductor, and the insulating film has a two-layer structure of a crosslinked layer and an adhesive layer. A heat-sealed portion of a lead conductor is covered with an adhesive layer, and the outside thereof is covered with a crosslinked layer.

Patent Document 2 includes a lead conductor, a first insulating layer that directly covers at least a part of the lead conductor, and a second insulating layer that covers the first insulating layer. Lead wire for non-aqueous electrolyte battery (tab lead) formed from a crosslinked resin composition containing olefin crystal / ethylene butene / olefin crystal block polymer and polypropylene in a mass ratio of 10:90 to 40:60. Is disclosed.

Japanese Unexamined Patent Publication No. 2011-103245 WO2018 / 074090

The present disclosure is a battery tab lead including a lead conductor and a resin layer covering a heat-sealed portion of the lead conductor.
The resin layer has a conductor adhesive layer provided on the lead conductor side, an intermediate layer, and a packaging material adhesive layer provided on the side of the intermediate layer opposite to the conductor adhesive layer side.
The conductor adhesive layer contains a polyolefin resin and contains
The intermediate layer contains a crosslinked polyolefin resin, and the packaging material adhesive layer contains a polyolefin resin and has an elastic modulus at 200 ° C. of 0.1 MPa or more and 15 MPa or less.

It is a perspective view which shows the vicinity of the heat fusion part of an example of a tab lead of this disclosure. It is a schematic cross-sectional view which shows typically the cross section of the heat fusion part of the tab lead of this disclosure. It is a schematic cross-sectional view which shows typically the cross section of the heat fusion part of the conventional tab lead. It is sectional drawing which shows the cross-sectional structure of an example of the non-aqueous electrolyte battery using the tab lead of this disclosure. It is sectional drawing which shows typically the heat fusion part using the tab lead of this disclosure. It is sectional drawing which shows typically the heat fusion part using the conventional tab lead.

[Issues to be solved by this disclosure]
As described in

Patent Documents

1 and 2, by using a tab lead in which the heat-sealed portion of the lead conductor is covered with an adhesive layer and the outside thereof is covered with a crosslinked layer made of a crosslinked resin, at the time of heat fusion. It is possible to obtain excellent adhesiveness to the lead conductor while preventing a short circuit between the lead conductor and the metal layer of the sealed container. As a result, the obtained battery can suppress the leakage of the electrolytic solution and the infiltration of water from the outside.

However, when the opening of the battery encapsulation container is sealed by heat fusion using such a tab lead, the cross-linked layer of the tab lead and the laminate film of the encapsulation container do not adhere to each other, and a gap (cross-linked layer and laminated film) does not adhere. It was found that there may be a case where a gap is formed because the space between the film and the thermoplastic resin layer is not sufficiently filled. In particular, when the lead conductor has a flat plate shape and its thickness is thick, this void is likely to occur. If voids are generated, leakage of the electrolytic solution and ingress of water into the battery are likely to occur, which poses a problem in terms of battery reliability (property that the performance of the battery is unlikely to deteriorate). Therefore, it is desired to develop a tab lead that prevents the generation of voids as described above in the step of heat-sealing the opening (packaging material sealing step).

The present disclosure is a tab lead used for a battery, particularly a non-aqueous electrolyte battery, and can sufficiently prevent a short circuit between the lead conductor and the metal layer of the sealed container at the time of heat fusion of the opening of the sealed container when manufacturing the battery. Further, the resin layer and the lead conductor are sufficiently adhered to each other, and the tab lead and the laminate film of the encapsulation container are sufficiently adhered to provide a tab lead in which the generation of voids between the resin layer and the thermoplastic resin layer of the laminate film is suppressed. The task is to do.

[Means to solve problems]
As a result of the study, the present inventor has attached a resin layer covering the heat-sealed portion of the lead conductor together with a conductor adhesive layer capable of adhering to the lead conductor and an intermediate layer made of crosslinked resin, and the conductor adhesive layer of the intermediate layer. If the packaging material adhesive layer provided on the opposite side to the above is included, and the packaging material adhesive layer has an elastic coefficient in a specific range formed by using a polyolefin resin, a tab lead that solves the above-mentioned problems can be obtained. We have completed the tab lead for batteries of the present disclosure.

Aspects of the present disclosure made to solve the above problems
A tab lead for a battery including a lead conductor and a resin layer that covers a heat-sealed portion of the lead conductor.
The resin layer has a conductor adhesive layer provided on the lead conductor side, an intermediate layer, and a packaging material adhesive layer provided on the side of the intermediate layer opposite to the conductor adhesive layer side.
The conductor adhesive layer contains a polyolefin resin and contains
The intermediate layer contains a crosslinked polyolefin resin, and the packaging material adhesive layer is a tab lead for a battery containing a polyolefin resin and having an elastic modulus of 0.1 MPa or more and 15 MPa or less at 200 ° C.

In a more preferred embodiment of the present disclosure, the packaging material adhesive layer has an elastic modulus of 1.0 MPa or more and 10 MPa or less at 200 ° C.

[Effect of the present disclosure]
When a battery, for example, a non-aqueous electrolyte battery is manufactured using the tab lead for a battery of the present disclosure, the resin layer and the lead conductor are sufficiently adhered to each other when the opening of the sealed container is heat-sealed, and the lead conductor and the lead conductor are sealed. It is possible to sufficiently prevent the occurrence of a short circuit with the metal layer of the container. Further, since the resin layer and the thermoplastic resin layer of the laminated film (encapsulated container) are in close contact with each other and the generation of voids between the layers is suppressed, problems such as leakage of the electrolytic solution and invasion of water from the outside into the battery are problems. It is possible to easily manufacture a battery having excellent reliability.

[Form for implementing the present disclosure]
Hereinafter, a mode for carrying out the present disclosure will be specifically described. It should be noted that the present invention is not limited to the following contents, but is indicated by the scope of claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

Aspects of the present disclosure are:
A tab lead for a battery including a lead conductor and a resin layer that covers a heat-sealed portion of the lead conductor.
The resin layer has a conductor adhesive layer provided on the lead conductor side, an intermediate layer, and a packaging material adhesive layer provided on the side of the intermediate layer opposite to the conductor adhesive layer side.
The conductor adhesive layer contains a polyolefin resin and contains
The intermediate layer contains a crosslinked polyolefin resin, and the packaging material adhesive layer is a tab lead for a battery containing a polyolefin resin and having an elastic modulus of 0.1 MPa or more and 15 MPa or less at 200 ° C.

(Battery tab lead configuration of the present disclosure)
The battery tab lead (hereinafter, also simply referred to as a tab lead) of the present disclosure includes a lead conductor and a resin layer that covers a heat-sealed portion of the lead conductor, and the resin layer is a packaging material in addition to a conductor adhesive layer and an intermediate layer. It is characterized by having an adhesive layer.
FIG. 1 is a perspective view showing the vicinity of a heat-sealed portion of an example of a battery tab lead of the present disclosure. In FIG. 1, 1 is a lead conductor and 2 is a resin layer. As shown in FIG. 1, the surface of the heat-sealed portion A (the portion that is heat-sealed when the sealed container is sealed) of the lead conductor 1 is covered with the resin layer 2. The encapsulation container and the lead conductor 1 are adhered (heat-sealed) via the resin layer 2.

FIG. 2 is a schematic cross-sectional view schematically showing a cross section of a heat-sealed portion of the battery tab lead of FIG. The resin layer 2 is composed of a conductor adhesive layer 3, an intermediate layer 4, and a packaging material adhesive layer 5. FIG. 3 is a cross-sectional view schematically showing a cross section of a heat-sealed portion of a conventional battery tab lead. In FIG. 3, 11 is a lead conductor, 21 is a resin layer, and the resin layer 21 is composed of a conductor adhesive layer 31 and a crosslinked layer 41. The battery tab lead of the present disclosure shown in FIG. 2 differs from the conventional battery tab lead shown in FIG. 3 in that it has a packaging material adhesive layer 5 in addition to the conductor adhesive layer 3 and the intermediate layer 4. ing.

The resin layer 2 includes the conductor adhesive layer 3, the intermediate layer 4, and the packaging material adhesive layer 5 as essential components, but may have other layers. For example, a layer for improving the adhesiveness between the conductor adhesive layer 3 and the intermediate layer 4 and / or between the intermediate layer 4 and the packaging material adhesive layer 5 may be provided. Since a polyolefin resin is used for the conductor adhesive layer 3, the intermediate layer 4, and the packaging material adhesive layer 5, when a layer for improving the adhesiveness between the layers is provided, the polyolefin resin is used as the layer. Layer is preferred.
As described above, the resin layer 2 may be composed of three or more layers.

Next, each component of the battery tab lead of the present disclosure will be described.

(Conductor adhesive layer)
The conductor adhesive layer is a layer provided on the lead conductor side in the resin layer and adheres to the lead conductor.
The conductor adhesive layer contains a thermoplastic polyolefin resin that can be adhered to the lead conductor. Examples of the polyolefin resin include polyethylene, polypropylene, ethylene-based elastomers, styrene-based elastomers, and ionomer resins obtained by cross-linking a copolymer of ethylene and methacrylic acid with Na, Mg, K, or the like. The resin contained in the conductor adhesive layer is preferably a resin having a high adhesive strength to the lead conductor. As the resin contained in the conductor adhesive layer, a resin obtained by modifying the above-mentioned polyolefin resin with maleic acid, acrylic acid, methacrylic acid, maleic anhydride, or an epoxy group is also preferable because the modification improves the adhesive strength with the lead conductor. used. In particular, a maleic anhydride-modified polyolefin resin can be preferably used.

The conductor adhesive layer may be composed of only a thermoplastic polyolefin resin that can be adhered to the lead conductor, or may contain other components. Various additives such as flame retardants, ultraviolet absorbers, light stabilizers, heat stabilizers, lubricants, and colorants can be mixed in the conductor adhesive layer. The conductor adhesive layer containing the thermoplastic polyolefin resin that can be adhered to the lead conductor and various additives is such that the polyolefin resin and the additives are used in an open roll, a pressure kneader, a single-screw mixer, a twin-screw mixer, or the like. After mixing using a known mixing device of the above, it can be produced by forming a film-like layer by extrusion molding such as T-die molding and inflation molding.
The optimum thickness of the conductor adhesive layer varies depending on the thickness of the lead conductor, but is usually preferably 20 μm or more and 250 μm or less.

(Middle layer)
The intermediate layer contains a crosslinked polyolefin resin. By using a polyolefin resin as a forming material, the intermediate layer can obtain excellent adhesiveness to a conductor adhesive layer made of a polyolefin resin that can be adhered to a lead conductor. In particular, when a polyolefin resin having the same or similar chemical structure as the polyolefin resin constituting the conductor adhesive layer is used, better adhesiveness to the conductor adhesive layer can be obtained.
Examples of the crosslinked polyolefin resin include a crosslinked polypropylene resin or a crosslinked body of a resin composition containing a polypropylene resin and a thermoplastic elastomer in a mass ratio of 90:10 to 60:40. .. Since this resin composition has excellent crosslinkability, by using this resin composition for forming an intermediate layer, it becomes possible to crosslink even if the amount of the following cross-linking aid is reduced, and molding equipment and products using the cross-linking aid can be used. It is possible to suppress the adverse effect on.
Examples of the thermoplastic elastomer include ethylene / butene copolymer resin, ethylene / octene copolymer resin, olefin crystal / ethylene butene / olefin crystal block polymer, polypropylene-based elastomer such as Toughmer PN2070 manufactured by Mitsui Chemicals, Inc. and the like. can. As the thermoplastic elastomer, at least one selected from these can be used.

Polyolefin resin has improved heat-resistant deformability by cross-linking, and is less likely to be thermally deformed even when heated above the melting point of the resin. Therefore, by providing an intermediate layer containing the crosslinked polyolefin resin on the surface of the heat-sealed portion of the lead conductor, thermal deformation and melting of the intermediate layer are suppressed even when the tab leads are heat-sealed to the opening of the encapsulation container. , It is possible to prevent a short circuit between the lead conductor and the metal layer of the sealed container.

Examples of the method for cross-linking the polyolefin resin include cross-linking by irradiation with ionizing radiation such as electron beam and gamma ray, chemical cross-linking with peroxide and the like, and silane cross-linking. Among these, the method by irradiation with ionizing radiation is preferable from the viewpoint of productivity, ease of control, and the like.
When cross-linking is performed by irradiation with ionizing radiation, a cross-linking aid may be added to the material for forming the intermediate layer together with the polyolefin resin before cross-linking, if necessary. Examples of this cross-linking aid include compounds containing at least two unsaturated groups in the molecule, specifically, triallyl isocyanurate, triallyl cyanurate, and tris (2-acryloyloxyethyl) isocyanurate. , Trimethylolpropane trimethacrylate, pentaerythritol triacrylate, ethine glycol dimethacrylate and the like.

The cross-linking of the olefin resin constituting the intermediate layer can be confirmed, for example, by immersing the sample in xylene at 120 ° C. for 24 hours, and then the insoluble matter remains.
The degree of cross-linking in the cross-linked polyolefin resin is preferably such that the gel fraction is 20% to 90%. Here, the gel fraction is a value measured by the method shown below.
(Measurement method of gel fraction)
Approximately 1.0 g of a sample (crosslinked polyolefin resin (intermediate layer)) (this weight is W1) is immersed in xylene at 120 ° C. for 24 hours, the liquid portion is discarded, and the solid portion is at 120 ° C. Heat for 3 hours to dry to remove xylene components. Then, the weight of the solid portion (referred to as W2) is measured, and (W2 / W1) × 100 (%) is defined as the gel fraction.

If the gel fraction is less than 20%, cross-linking tends to be insufficient and the prevention of short circuit between the lead conductor and the metal layer of the encapsulation container tends to be insufficient. On the other hand, when the gel fraction exceeds 90%, the adhesiveness with the packaging material adhesive layer is lowered, and the electrolytic solution tends to leak easily. The amount of the cross-linking aid and the irradiation amount of the ionizing radiation are preferably selected from the range in which the degree of cross-linking is within the above range and the resin is not deteriorated.

The fact that the olefin resin constituting the intermediate layer is crosslinked can be confirmed by the heat deformation residual ratio of the intermediate layer in addition to the above-mentioned method. In this case, the thermal deformation residual ratio of the intermediate layer is measured by a thermomechanical analysis (TMA (Thermal Mechanical Analysis)) method, and if the thermal deformation residual ratio is 20% or more, it is determined that the olefin resin is crosslinked. I decided to.

In addition to the above-mentioned polyolefin resin and cross-linking aid, various additives such as flame retardants, ultraviolet absorbers, light stabilizers, heat stabilizers, lubricants, and colorants can be mixed in the material for forming the intermediate layer. .. When the forming material contains a polyolefin resin and an optional cross-linking aid and additive, the intermediate layer is prepared by using an open roll of the polyolefin resin, the cross-linking aid and the additive before cross-linking, a pressure kneader, and the like. After mixing using a known mixing device such as a single-screw mixer or a twin-screw mixer, extrusion molding is performed with a T-die, an inflation extruder or the like to form a film-like layer, which is then obtained by the method described above. This can be done by cross-linking the olefin resin contained in the film-like layer. The intermediate layer may be composed of only the crosslinked polyolefin resin, or may be composed of the crosslinked polyolefin resin and other components such as a crosslinking aid and an antioxidant.
The optimum thickness of the intermediate layer varies depending on the thickness of the lead conductor, but is usually preferably 10 μm to 200 μm.

(Packaging material adhesive layer)
The packaging material adhesive layer is a layer containing a polyolefin resin having an elastic modulus of 0.1 MPa or more and 15 MPa or less at 200 ° C. measured by the method shown below. The packaging material adhesive layer is provided on the side opposite to the conductor adhesive layer with respect to the intermediate layer. By providing a packaging material adhesive layer having an elastic modulus in the above range and containing a polyolefin resin, a gap (a resin layer and a thermoplastic resin layer of the laminate film) between the resin layer and the laminate film (encapsulated container) can be provided. It is possible to suppress the occurrence of gaps (locations that are not sufficiently filled and become voids) (hereinafter, the property of suppressing the generation of voids may be referred to as "fillability"). Therefore, problems such as leakage of the electrolytic solution and infiltration of water from the outside are suppressed, and a highly reliable non-aqueous electrolyte battery (with suppressed deterioration of battery performance) can be manufactured.

(Measuring method of elastic modulus at 200 ° C)
The method for measuring the elastic modulus at 200 ° C. is shown below.
The tab lead insulating film is cross-sectioned using a microtome so that each layer can be observed. Using an atomic force microscope (Asylum Research Cypher ES manufactured by Oxford Instruments), using an indenter made of silicon with a tip diameter of nominally 20 nm, the film thickness at 1 μm intervals and 1 Hz speed in a 200 ° C environment. 20 points in the parallel direction and 20 points in the vertical direction, totaling about 400 points, are mapped for force curve measurement. A histogram is created at 1 MPa intervals based on the obtained data, and the mode is defined as "elastic modulus at 200 ° C.".

If the elastic modulus of the packaging material adhesive layer at 200 ° C. is less than 0.1 MPa, the resin will flow out significantly during heat fusion, and the problem of large wetting and spreading on the surface of the lead conductor and the end portion of the lead conductor is likely to occur.
On the other hand, when the elastic modulus of the packaging material adhesive layer at 200 ° C. exceeds 15 MPa, it becomes difficult to sufficiently fill the space between the resin layer near the end of the lead conductor and the thermoplastic resin layer of the laminate film, and voids are generated. It will be easier. As a result, problems such as leakage of electrolytic solution and infiltration of water from the outside are likely to occur. The elastic modulus at 200 ° C. is preferably in the range of 1.0 MPa or more and 10.0 MPa or less.
The elastic modulus of the polyolefin resin for forming the packaging material adhesive layer at 200 ° C. is preferably 0.1 MPa or more and 15 MPa or less, and more preferably 1.0 MPa or more and 10 MPa or less.

In addition to the elastic modulus in the above range, the packaging material adhesive layer is desired to have excellent adhesiveness to the thermoplastic resin layer of the intermediate layer and the laminate film of the encapsulation container. Therefore, as the polyolefin resin for forming the packaging material adhesive layer, a polyolefin resin having the same or similar chemical structure as the polyolefin resin before cross-linking, which is the material for forming the intermediate layer, is preferable.

The thickness of the packaging material adhesive layer is usually preferably 10 μm or more and 200 μm or less, but this preferable range varies depending on the thickness of the lead conductor, and is preferably 0.1 times or more and 1.0 times or less the thickness of the lead conductor. When the thickness of the packaging material adhesive layer is thinner than the above range, it becomes difficult to fill the space between the resin layer near the end of the lead conductor and the thermoplastic resin layer of the laminate film with resin, and voids are likely to occur (filling property). Will decrease). On the other hand, even when the packaging material adhesive layer is made thicker than the above range, a large amount of heat is required to melt the packaging material adhesive layer, so that the resin is likely to be insufficiently melted and the filling property is lowered.
However, if the thickness of the thermoplastic resin layer (sealant layer) of the laminated film (on the side that is heat-sealed with the resin layer of the tab lead) is thin, the space between the resin layer and the thermoplastic resin layer of the laminated film is sufficient. In order to fill and suppress the generation of voids, it is desirable to thicken the packaging material adhesive layer. When the sealant layer of the laminated film is made of a polyolefin resin, it is usually preferable that the total thickness of the sealant layer (the thermoplastic resin layer) of the laminated film and the packaging material adhesive layer is 80 μm or more.

The packaging material adhesive layer may be composed of only a polyolefin resin or may contain other components. Various additives such as flame retardants, ultraviolet absorbers, light stabilizers, heat stabilizers, lubricants, and colorants can be mixed in the packaging material adhesive layer. To prepare the packaging material adhesive layer containing the polyolefin resin and various additives, the polyolefin resin and the above additives are mixed with a known mixing device such as an open roll, a pressure kneader, a single-screw mixer, or a twin-screw mixer. After mixing, it can be extruded into a film by a T-die, an inflation extruder or the like.

(Lead conductor)
The shape of the lead conductor is not particularly limited, but as the lead conductor used in the lithium ion battery which is a non-aqueous electrolyte battery, a flat metal having a thickness of 50 μm to 2 mm and a width of about 1 mm to 200 mm is often preferable. Examples of the metal used as the lead conductor include aluminum, titanium, nickel, copper, nickel-plated copper and the like. When the lead conductor is used in a lithium ion battery, aluminum or titanium or an alloy thereof is often preferable as the lead conductor connected to the positive electrode plate, and the lead conductor connected to the negative electrode plate is often used. Nickel or copper or alloys thereof are often preferred.

(Preparation of tab lead of the present disclosure)
In the tab lead of the present disclosure, for example, a conductor adhesive layer, an intermediate layer, and a packaging material adhesive layer are provided in this order on both surfaces at positions corresponding to the heat-sealed portion of a flat plate-shaped lead conductor (part A in FIG. 1). The resin layer containing the conductor can be produced by a method in which the conductor adhesive layer (resin layer) and the lead conductor are heat-sealed by being brought into close contact with each other so that the conductor adhesive layer is on the lead conductor side and then heated.
The resin layer including the conductor adhesive layer, the intermediate layer, and the packaging material adhesive layer can be produced by superimposing each film-like layer produced by the above-mentioned method or the like and laminating them by thermal laminating.
The heating temperature, pressure, and heating time for heat fusion and heat laminating are the same as for the production of conventional tab leads, and a simple preliminary experiment is performed if necessary with reference to conventionally known conditions. It can be determined by adjusting as appropriate.

(Manufacturing of non-aqueous electrolyte batteries)
The laminate film forming the battery encapsulation container is composed of a metal layer and a thermoplastic resin layer (sealant layer) that insulates and coats both surfaces thereof.
For the encapsulation container of the non-aqueous electrolyte battery, for example, a pair of the laminated films having a rectangular shape of a predetermined size are prepared, these are laminated so as to face each other, and the three sides around the rectangle are designated by using a sealing machine. It can be produced by heat-sealing by a desired seal width under heating conditions. In this way, a bag-shaped enclosed container having an opening on one side can be produced.
Other methods for producing the enclosed container include deep drawing of the laminated film. The method for producing the enclosed container is not particularly limited as long as it can produce a bag-shaped enclosed container having an opening on one side and can provide a volume for accommodating the battery constituent members inside.

In the sealed container produced as described above, a positive electrode plate and a negative electrode plate to which the tab lead of the present disclosure is connected to one end thereof, an electrolytic solution, and the like are placed. The heat-sealed portion of the tab lead, that is, the resin layer covering the surface of the lead conductor is located at the opening of the encapsulation container, and the other end of the tab lead is extended to the outside of the encapsulation container, and then the opening is heated and added. A non-aqueous electrolyte battery can be manufactured by pressing and heat-sealing (sealing the packaging material).
For the heating temperature, pressurizing pressure, and heating / pressurizing time at the time of heat fusion (packaging material seal), refer to the conditions conventionally adopted in the manufacture of non-aqueous electrolyte batteries, and perform a simple preliminary experiment if necessary. Can be easily selected by performing the above and adjusting as appropriate.

FIG. 4 is a cross-sectional view showing the structure of the non-aqueous electrolyte battery manufactured as described above. In FIG. 4, 6 is a positive electrode plate, 7 is a negative electrode plate, 8 is a tab lead of the present disclosure in which one end is connected to a positive electrode plate 6 or a

negative electrode plate

7, and 9 covers the surface of a heat-sealed portion of a lead conductor. It is a resin layer. In FIG. 4, 52 is a non-aqueous electrolyte, and 53 is a sealing portion of the sealed container 51. As shown in FIG. 4, the resin layer 9 of the tab lead 8 is located at the heat-sealing portion 10 (opening) of the sealed container 51.

The heat-sealing portion 10 of the enclosed container 51 is heat-sealed (packaging material seal) by heating and pressurizing. 5 and 6 are views showing the state of the heat-sealed portion after heat-sealing. FIG. 5 is a schematic cross-sectional view schematically showing a cross section of a heat-sealed portion using the tab leads of the present disclosure, and FIG. 6 is a schematic cross-sectional view schematically showing a cross section of a heat-sealed portion using a conventional tab lead. It is a cross-sectional view.

In the examples of FIGS. 5 and 6, the laminate film 101 covers the metal layer 102 made of an aluminum foil, the polyamide resin layer 103 that covers the first surface of the metal layer 102, and the second surface of the metal layer 102. It is composed of a sealant layer 104 made of polypropylene resin. Further, in the example of FIG. 5, the resin layer 2 includes the conductor adhesive layer 3, the intermediate layer 4, and the packaging material adhesive layer 5. In the example of FIG. 6, the resin layer 21 includes the conductor adhesive layer 31 and the crosslinked layer 41. The intermediate layer 4 included in the resin layer 2 of the example of FIG. 5 and the crosslinked layer 41 included of the resin layer 21 of the example of FIG. 6 are both layers containing a crosslinked resin, and are crosslinked by heating during heat fusion. The layer containing the crosslinked resin is not easily deformed. Therefore, in the examples of FIGS. 5 and 6, a short circuit between the metal layer 102 and the lead conductor 1 or the lead conductor 11 is prevented.

In the example of FIG. 6, a gap 105 is formed between the sealant layer 104 near the end of the lead conductor 11 and the cross-linking layer 41, but in the example of FIG. 5, the sealant near the end of the lead conductor 1 is formed. The space between the layer 104 and the intermediate layer 4 (the portion indicated by (105)) is filled with the packaging material adhesive layer 5.
By forming the packaging material adhesive layer 5 using a polyolefin resin (polypropylene resin or the like) that is melted by heating during heat melting, the polyolefin resin (polypropylene resin or the like) is melted during heat melting, and the end portion of the lead conductor 1 is formed. The voids generated between the nearby sealant layer 104 and the intermediate layer 4 can be filled. As a result, problems such as leakage of the electrolytic solution and infiltration of water from the outside can be suppressed.

The battery to which the tab lead of the present invention is applied is not limited to the above-mentioned non-aqueous electrolyte battery, but is a battery in which the encapsulation container is formed of a metal foil, a laminate film containing a metal layer, or a laminate material. If there is, there is no particular limitation.

(Manufacturing of lead conductor)
A conductor plate made of the materials described in the columns of "Conductor: Material" in Tables 1 and 2, having the thickness described in the same table, having a width of 50 mm and a length of 45 mm was prepared and used as a lead conductor.

(Resin layer)
1) Tables 1 and 2 show the following resins a), b) or c) under the conditions of an extrusion temperature of 220 ° C. and a take-up speed of 10 m / min using a single-layer T-die film forming machine. A film (layer) of material and thickness was formed.
a) Adomah QE060: Maleic anhydride-modified polypropylene, elastic modulus at 200 ° C., manufactured by Mitsui Chemicals, Inc. (indicated as "metal-adhesive PP" in the table).
b) Noblen FL6747: Polypropylene, elastic modulus at 200 ° C., manufactured by Sumitomo Chemical Co., Ltd. (indicated as "PP" in the table)
c) Noblen S131: polypropylene, elastic modulus at 200 ° C., 32 MPa, manufactured by Sumitomo Chemical Co., Ltd. (polypropylene with low fluidity: indicated as "PP2" in the table)
In the table, the layer indicated as "crosslinked PP" is b) the layer of Nobleen FL6747 ("PP") is irradiated with an electron beam having an acceleration voltage of 120 kV so that the dose is 120 kGy using an electron beam irradiation device. It is a layer in which a resin is crosslinked. The elastic modulus of the resin crosslinked under the same conditions at 200 ° C. is 19 MPa.
The films of each layer have a width of 10 mm, are stacked in the order shown in Tables 1 and 2 (in the order of the first layer to the fifth layer in the table), and thermocompression bonded using a laminator machine to obtain a resin layer (laminated film). Was produced.

(Making tab leads)
The resin layer prepared by the above method is laminated on both surfaces of the lead conductor so that the first layer is on the laminate film side (outermost layer: packaging material adhesive layer), and thermocompression bonding (heat pressing) is performed to prepare a tab lead. did.

(Making a laminated film)
A sealant made of the material shown in Tables 1 and 2 (PP having a melting point of 135 ° C.) and having the thickness shown in the same table (the sealant layer of the laminated film) is extruded and laminated to have the thickness shown in Tables 1 and 2. Attach to aluminum foil (apply adhesive PP resin to the interface with aluminum foil).
Then, a solvent adhesive is applied to the aluminum foil side, a polyamide film produced by extrusion molding and having the thickness shown in Tables 1 and 2 is laminated on the polyamide film, and then roll-pressed at room temperature to obtain the polyamide film. I pasted it. Then, it was cut into an A3 size rectangle to prepare a laminated film.

The laminate film obtained above was laminated on both surfaces of the tab lead obtained above so that the sealant was on the tab lead side, and then thermocompression bonding (heat pressing) was performed. For the obtained sample, the filling property near the end of the conductor was determined by the following method. The results are shown in the "Fillability" column of Tables 1 and 2.

(Method of determining filling property)
The conductor end of the sample was cut out, embedded in an epoxy resin, and polished with a polishing machine. The polished cross section was observed 10 to 100 times with an optical microscope, and the presence or absence of voids having a diameter of 1 μm or more was examined. As a result of the observation, the case where no void was found was regarded as good, and the case where the void was found was regarded as poor, and is shown in the “Fillability” column of Tables 1 and 2.

From the results shown in Tables 1 and 2, it is made of non-crosslinked resin (PP) on the outside of the layer made of crosslinked resin (PP) (on the side of the laminated film to be heat-sealed), and has an elastic modulus of 200 ° C. In Experiments 2 to 4, 6 to 10 in which layers in the range of 0.1 MPa or more and 15 MPa or less were provided, the generation of voids between the laminated film and the tab leads when the laminated film and the tab leads were heat-sealed was suppressed. It has been shown that the filling property is improved.
On the other hand, a layer made of a non-crosslinked resin (PP) and having an elastic modulus at 200 ° C. of 0.1 MPa or more and 15 MPa or less is not provided, and a layer made of a crosslinked resin (PP) is the outermost layer (heat).

Experiments

1 and 5 which are layers in contact with the laminated film to be fused: packaging material adhesive layer), and a layer made of resin (PP) whose outermost layer side is not crosslinked, but whose elastic modulus at 200 ° C. exceeds 15 MPa. In one experiment 11, voids were seen and the filling property was inferior.

That is, in order to obtain excellent filling property, the elastic modulus at 200 ° C. is 0.1 MPa or more and 15 MPa or less on the outside of the layer made of the crosslinked resin (PP), and the non-crosslinked resin (PP). It has been shown that a layer consisting of is necessary.

However, among Experiments 2 to 4 and 6 to 10 in which the filling property is improved, the non-crosslinked layer (packaging adhesive layer) outside the layer (intermediate layer) made of crosslinked resin (PP) In Experiment 8 (the thickness of the packaging material adhesive layer (outermost layer: PP) is 25 μm and the thickness of the sealant layer is 50 μm, totaling 75 μm) in which the total thickness of the thickness and the sealant layer is less than 80 μm, the filling property is inferior to that of the other cases. Although the generation of voids between the laminated film and the tab lead was suppressed, it could not be sufficiently prevented. From this result, it is shown that the total thickness of the packaging material adhesive layer and the sealant layer of the laminated film is preferably 80 μm or more.

1, 11

Lead conductors

2, 21

Resin layers

3, 31 Conductor adhesive layer 4 Intermediate layer 41 Bridge layer 5 Packaging material adhesive layer A Heat fusion part 6 Positive electrode plate 7 Negative electrode plate 8 Tab lead 9 Resin layer 10 Heat fusion part 51 Encapsulation Container 52 Non-aqueous electrolyte 53 Sealing part 101 Laminated film 102 Metal layer (aluminum foil)
103 Polyamide resin layer 104 Sealant layer (polypropylene resin)
105 void

Claims

A tab lead for a battery including a lead conductor and a resin layer that covers a heat-sealed portion of the lead conductor.
The resin layer has a conductor adhesive layer provided on the lead conductor side, an intermediate layer, and a packaging material adhesive layer provided on the side of the intermediate layer opposite to the conductor adhesive layer side.
The conductor adhesive layer contains a polyolefin resin and contains
A tab lead for a battery, wherein the intermediate layer contains a crosslinked polyolefin resin, and the packaging material adhesive layer contains a polyolefin resin and has an elastic modulus of 0.1 MPa or more and 15 MPa or less at 200 ° C.
The battery tab lead according to claim 1, wherein the packaging material adhesive layer has an elastic modulus of 1.0 MPa or more and 10 MPa or less at 200 ° C.
The first or second claim, wherein the polyolefin resin forming the intermediate layer is a polypropylene resin or a resin composition containing a polypropylene resin and a thermoplastic elastomer at a mass ratio of 90:10 to 60:40. Tab lead for batteries.
The third aspect of claim 3, wherein the thermoplastic elastomer is at least one resin selected from an ethylene / butene copolymer resin, an ethylene / octene copolymer resin, an olefin crystal / ethylene butene / olefin crystal block polymer, and a PP-based elastomer. Tab lead for batteries.
The battery tab lead according to any one of claims 1 to 4, wherein the polyolefin resin contained in the conductor adhesive layer is maleic anhydride-modified polyolefin.
The battery tab lead according to any one of claims 1 to 5, wherein the thickness of the conductor adhesive layer is 20 μm or more and 250 μm or less.
The battery tab lead according to any one of claims 1 to 6, wherein the thickness of the packaging material adhesive layer is 0.1 times or more and 1.0 times or less the thickness of the lead conductor.
The battery tab lead according to claim 7, wherein the thickness of the packaging material adhesive layer is 10 μm or more and 200 μm or less.
The battery tab lead according to any one of claims 1 to 8, wherein the resin layer is composed of three or more layers.