JP2017033820A - Resin film for terminal, tab using the same, and power storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin film for a terminal capable of reducing the thickness (total thickness) thereof while being capable of sufficiently ensuring tightly sealing performance and insulating properties, which is used for a power storage device that includes a power storage device body, a packaging material and a resin film for a terminal, the device being tightly sealed by sealing the packaging material arranged on upper and lower faces of the power storage device body on the periphery of the power storage device body, a metal terminal extending to the outside from a seal face of the packaging material, and the metal terminal and the packaging material being sealed via the resin film for a terminal.SOLUTION: A resin film for a terminal includes a thermally fusible resin layer 31 and a heat-resistant insulating layer 32, the heat-resistant insulating layer having a thickness of equal to or less than the thickness of the thermally fusible resin layer and equal to or more than 0.1 times the thickness of the thermally fusible resin layer and having the total thickness of equal to or more than 15 μm.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a resin film for a terminal used for an electricity storage device such as a lithium ion secondary battery.

  In recent years, demands for miniaturization of portable devices and effective utilization of natural power generation energy have increased, and research and development of lithium ion secondary batteries with higher voltage and high energy density are being conducted.

  As a packaging material used for the lithium ion secondary battery, metal cans have been used in the past, but because of the low manufacturing cost for demands such as thinning and diversification of products to be applied, A packaging material in which a laminated body in which a metal layer (for example, an aluminum foil) and a resin film are laminated into a bag shape is often used.

  As shown in FIG. 4, for example, the lithium ion secondary battery using the bag-shaped packaging material is configured to include the power storage device body 1, the packaging material 2, and the terminal resin film 3. . A packaging material 2 having a larger area than the electricity storage device body 1 is disposed on the upper and lower surfaces of the electricity storage device body 1. The packaging material 2 is heat-sealed and sealed at a portion 2 a extending around the electricity storage device body 1. doing. In general, the packaging material 2 is formed by laminating an electrically insulating resin layer on the inner surface side of an aluminum foil in order to prevent permeation of air and moisture.

  And the electrical storage device main body 1 has the metal terminal 11 connected to the positive / negative electrical power collector, respectively, and has extended from the said sealing surface of the packaging materials 2 to the exterior of an electrical storage device. And in the position where this metal terminal 11 and the seal | sticker part 2a cross | intersect, the perimeter of the outer peripheral surface containing the upper and lower surfaces and side surface of the metal terminal 11 is covered with the resin film for terminals, Therefore, the metal terminal 11 And the packaging material 2 are sealed via the terminal resin film 3.

  As the terminal resin film 3, for example, a film having a two-layer structure or a three-layer structure is used. That is, Patent Document 1 describes a terminal resin film 3 composed of two layers of a high fluidity acid-modified polypropylene resin layer and a low fluidity polypropylene resin layer. By superposing the terminal resin film 3 on the metal terminal 11 and hot pressing, the highly fluid acid-modified polypropylene resin layer is melted and welded. On the other hand, since the low-fluidity polypropylene resin layer has poor fluidity, the insulation between the aluminum foil in the packaging material 2 and the metal terminal 11 can be maintained. In addition to the two layers, a high fluidity acid-modified polypropylene resin layer, a low fluidity polypropylene resin layer, and a low fluidity polypropylene resin layer are laminated on the low fluidity polypropylene resin layer side. A resin film for terminals 3 having a three-layer structure in which high-fluidity acid-modified polypropylene resin layers are laminated in this order is described.

  Patent Document 2 describes a terminal resin film 3 having a two-layer structure or a three-layer structure using a low-fluidity acid-modified polypropylene resin layer instead of the low-fluidity polypropylene resin layer. .

Japanese Patent No. 4498639 Japanese Patent No. 4508477

  By the way, the market of lithium ion secondary batteries is roughly classified into in-vehicle use, consumer use, and mobile use. In-vehicle lithium ion secondary batteries use thick terminal resin films, but consumer and mobile lithium ion secondary batteries have a smaller size and a larger battery capacity. Therefore, a thin resin film for a terminal is required.

  In order to reduce the thickness (total thickness) of the terminal resin film in this way, in the case of a two-layered terminal resin film, the thickness of the highly fluid acid-modified polypropylene resin layer that adheres to the metal terminal It is necessary to reduce the thickness, or to reduce the thickness of the low fluidity polypropylene-based resin layer. In addition, in the resin film for terminals having a three-layer structure, it is the same that the thickness of any one of these layers needs to be reduced.

  However, if the thickness of the high-fluidity acid-modified polypropylene resin layer that adheres to the metal terminal is reduced, the amount of the resin that wraps around the side surface of the metal terminal is reduced, which makes sealing difficult and leads to electrolyte leakage and Moisture penetration may occur.

  On the other hand, if the thickness of the low-fluidity polypropylene resin layer is reduced, the polypropylene resin layer may be crushed when heat-sealed to the metal terminal, and there is a risk that the aluminum foil in the packaging material and the metal terminal are short-circuited. is there.

  Therefore, the acid-modified polypropylene resin layer having high fluidity needs to be sufficiently thick, and the thickness of the low-fluidity polypropylene-based resin layer needs to be 1.5 times or more that of the acid-modified polypropylene resin layer. (See Patent Documents 1 and 2).

  Therefore, an object of the present invention is to provide a resin film for a terminal capable of reducing the thickness (total thickness) although the sealing property and the insulating property can be sufficiently ensured.

  That is, the invention described in claim 1 is a terminal resin film that covers a part of the outer peripheral surface of the metal terminal of the electricity storage device, and includes a heat-fusible resin layer that adheres to the metal terminal, a heat-resistant insulating layer, It is the resin film for terminals characterized by satisfying the following conditions 1-3.

Condition 1: The electricity storage device satisfies the following conditions 1a to 1c.
Condition 1a: It is configured to include three members: a power storage device body, a packaging material, and a terminal resin film.
Condition 1b: The packaging material disposed on the upper and lower surfaces of the electricity storage device body is sealed and sealed around the electricity storage device body.
Condition 1c: The metal terminal extends from the sealing surface of the packaging material to the outside, and the metal terminal and the packaging material are sealed via a resin film for terminals.
Condition 2: The thickness of the heat-resistant insulating layer is not more than the thickness of the heat-fusible resin layer and not less than 0.1 times the thickness of the heat-fusible resin layer.
Condition 3: The total thickness of the terminal resin film is 15 μm or more.

  Next, the invention according to claim 2 is the resin film for terminals according to claim 1, comprising two layers of a heat-fusible resin layer and a heat-resistant insulating layer.

  Further, the invention described in claim 3 has a heat-fusible resin layer for packaging material laminated on the heat-resistant insulating layer side in addition to the two layers of the heat-fusible resin layer and the heat-resistant insulating layer. It is a resin film for terminals of Claim 1 characterized by these.

  The invention according to claim 4 is characterized in that the thickness of the heat-fusible resin layer for packaging material is equal to or thinner than the heat-fusible resin layer. This is a resin film for terminals.

  Moreover, invention of Claim 5 is a resin film for terminals in any one of Claims 1-4 whose total thickness is 60 micrometers or less.

  Moreover, invention of Claim 6 is equipped with the said metal terminal and the resin film for terminals in any one of Claims 1-5 arrange | positioned covering a part of outer peripheral surface of this metal terminal. It is a tab characterized by.

  The invention according to claim 7 is the tab according to claim 6, wherein the metal terminal has a thickness of 80 μm or less.

  The invention according to claim 8 is the tab according to claim 6 or 7, wherein the thickness of the heat-fusible resin layer is 25 to 100% of the thickness of the metal terminal. is there.

  Moreover, invention of Claim 9 is provided with the tab in any one of Claims 6-8, It is an electrical storage device characterized by the above-mentioned.

  The terminal resin film of the present invention has a total thickness of 15 μm or more, and has a heat-resistant insulating layer in its layer structure. For this reason, even if this heat-resistant insulating layer is thinned, sufficient insulation can be ensured. As can be seen from the examples and comparative examples described later, the thickness of the heat-resistant insulating layer needs to be at least 0.1 times that of the heat-fusible resin layer bonded to the metal terminal. If it is thin, sufficient insulation cannot be secured.

  And since the thickness of the heat-resistant insulating layer can be reduced in this way, even when the thickness of the heat-fusible resin layer is sufficiently increased to ensure sealing performance, The total thickness can be reduced. For example, the total thickness is 60 μm or less.

FIG. 1 relates to a specific example of a resin film for a terminal according to the present invention. FIG. 1A is a cross-sectional view of a resin film for a terminal having a two-layer structure, and FIG. FIG. It is sectional drawing which concerns on the specific example of a packaging material. It is a perspective view which concerns on the specific example of a tab. It is a perspective view which concerns on the specific example of an electrical storage device.

  The resin film for terminals according to the present invention is applied to an electricity storage device such as a lithium ion secondary battery. This power storage device has the same structure as a conventional power storage device. That is, as shown in FIG. 4, the power storage device body 1, the packaging material 2, and the terminal resin film 3 are provided, and the packaging material 2 disposed on the upper and lower surfaces of the power storage device body 1 is replaced with the power storage device. The main body 1 is sealed around each other. And the metal terminal 11 is extended outside from the said sealing surface of the packaging material 2, and this metal terminal 11 and the packaging material 2 are sealed via the resin film 3 for terminals.

  The terminal resin film 3 needs to be provided with a heat-fusible resin layer 31 and a heat-resistant insulating layer 32. The terminal resin film 3 may be composed of these two layers as shown in FIG. 1A, or in addition to these two layers as shown in FIG. A three-layer structure having the heat-fusible resin layer 33 for packaging material laminated on the layer side may be used. The heat-fusible resin layer 31 is bonded to the upper and lower surfaces and side surfaces of the metal terminal 11 by heat pressure. Since the heat-fusible resin layer 31 adheres to the upper and lower surfaces and the side surfaces of the metal terminal 11, the terminal resin film 3 seals the entire outer periphery of the metal terminal 11, and allows leakage of electrolyte solution and permeation of air and moisture. To prevent. Further, the heat-fusible resin layer 33 for packaging material is bonded to the inner surface of the packaging material 2. In order to distinguish the two, hereinafter, the heat-fusible resin layer 31 is referred to as “terminal heat-fusible resin layer 31”.

  Of these layers 31, 32, and 33, the thickness of the terminal heat-fusible resin layer 31 is preferably in the range of 25% to 100% of the thickness of the metal terminal 11. When the thickness of the terminal heat-fusible resin layer 31 is less than 25% of the thickness of the metal terminal 11, the molten terminal heat-fusible resin layer 31 is formed on the side surface of the metal terminal 11 as described later. This is because it is difficult to sufficiently wrap around and seal liquid-tight and air-tight. Further, it is sufficient that the terminal heat-fusible resin layer 31 has the same thickness as the metal terminal 11.

  Further, the thickness of the heat-resistant insulating layer 32 is not more than the thickness of the terminal heat-fusible resin layer 31 and needs to be not less than 0.1 times the thickness of the terminal heat-fusible resin layer 31. There is. When the heat-resistant insulating layer 32 is thicker than the terminal heat-fusible resin layer 31, it is difficult to reduce the total thickness of the terminal resin film 3. Further, when the heat-resistant insulating layer 32 is less than 0.1 times the terminal heat-fusible resin layer 31, the insulation between the metal terminal 11 and the aluminum in the packaging material 2 is insufficient, and both are conductive. There is a risk.

  The total thickness of the terminal resin film 3 may be arbitrary, but is desirably 60 μm or less. The thickness of the heat-fusible resin layer 33 for packaging material is preferably equal to or thinner than the heat-fusible resin layer 31 for terminals. In order to prevent curling of the terminal resin film 3, it is desirable that the terminal heat-fusible resin layer 31 and the packaging material heat-fusible resin layer 33 have the same thickness.

  The heat-resistant insulating layer 32 can be made of a resin that can maintain its insulating properties when the terminal resin film 3 is heat-sealed. Examples of such a resin include polypropylene resin, polyester resin, polycarbonate resin, polyacetal resin, polyamide resin, polyvinyl alcohol resin, polyvinylidene chloride resin, and polyvinylidene fluoride resin. Moreover, you may comprise the heat resistant insulating layer 32 with the resin which mixed the filler and the fiber and was reinforced. Further, the heat resistant insulating layer 32 may be made of a resin having a crosslinked structure. It is also possible to use a mixed resin in which fillers, fibers, or color pigments are mixed with these resins.

  In addition, as a polypropylene-type mixed resin, the thing of the state which polyethylene, ethylene-propylene rubber (EPR), etc. disperse | distributed to the island shape in polypropylene can be used. In this polypropylene-based mixed resin, the ethylene content is preferably 0.1 to 10% by mass, more preferably 1 to 7% by mass, and still more preferably 2 to 5% by mass. There exists a tendency for the adhesiveness at the time of melt | fusing the resin film for terminals to the metal terminal 11 that ethylene content is 0.1 mass% or more to improve. When the ethylene content is 10% by mass or less, it is possible to suppress the melting point of the mixed resin from being excessively lowered, and the liquid leakage prevention property tends to be improved when the electricity storage device is held for a long period of time in a high temperature environment.

The melting point of the polypropylene-based mixed resin is preferably 130 to 165 ° C.
More preferably, it is -155 degreeC, and it is still more preferable that it is 140-150 degreeC. When the melting point is 130 ° C. or higher, the liquid leakage prevention property tends to be improved when the electricity storage device is held for a long time in a high temperature environment. When the melting point is 165 ° C. or lower, the adhesion when the terminal resin film is fused to the metal terminal tends to be improved.

  The melting point of polypropylene is preferably 140 to 165 ° C, more preferably 145 to 163 ° C, and still more preferably 150 to 160 ° C. When the melting point is 140 ° C. or higher, the liquid leakage prevention property tends to be improved when the electricity storage device is held for a long time in a high temperature environment. When the melting point is 165 ° C. or lower, the adhesion when the terminal resin film is fused to the metal terminal at a low temperature tends to be improved.

  The weight average molecular weight of the homopolypropylene is preferably adjusted as appropriate so that the melting point falls within the above range, but is preferably 5,000 to 10,000,000, more preferably 10,000 to 1,000,000. 000.

  Examples of the resin having a crosslinked structure include a crosslinked acrylic resin, an epoxy resin, a phenol resin, a urea resin, a melamine resin, and a polyurethane resin.

  Examples of the filler mixed with these resins include silica particles, alumina particles, barium sulfate particles, and calcium carbonate particles. The average particle size of the filler is preferably 0.1 to 10 μm, and the filler content is preferably 0.5 to 20% by mass based on the total amount of the heat-resistant insulating layer 32.

  Moreover, as a fiber mixed with these resin, the fiber which consists of resin etc. whose melting | fusing point used for a cellulose resin or the said heat-resistant layer is 200 degreeC or more is mentioned, for example. The fiber may form a nonwoven fabric. The fiber content is preferably 0.5 to 70% by mass based on the total amount of the heat-resistant insulating layer 32.

  Moreover, as a coloring pigment, an organic pigment, an inorganic pigment, etc. can be used, for example. Examples of organic pigments include azo, phthalocyanine, quinacridone, anthraquinone, dioxazine, indigothioindigo, perinone-perylene, and isoindolenin, and inorganic pigments include carbon black. In addition, titanium oxide-based, cadmium-based, lead-based, oxide-based flume, and the like can be used. In addition, mica (mica) fine powder, fish scale foil, and the like can be used.

  Next, each of the terminal heat-fusible resin layer 31 and the packaging material heat-fusible resin layer 33 is, for example, a polyolefin resin or an acid modification in which a maleic anhydride is graft-modified to a polyolefin resin. A polyolefin resin or the like can be used. In addition, a mixed resin obtained by mixing a filler, fiber, or coloring pigment with these resins can also be used.

  Here, the polyolefin resin is preferably a polyolefin random copolymer from the viewpoint of adhesiveness. The polyolefin random copolymer is a copolymer obtained by randomly copolymerizing two or more olefin monomers. Examples of the olefin monomer include ethylene, propylene, 1-butene and the like.

  Specific examples of the polyolefin random copolymer include, for example, an ethylene-propylene random copolymer that is a copolymer of propylene and ethylene, a 1-butene-propylene random copolymer that is a copolymer of propylene and 1-butene, and propylene and ethylene. And ethylene-butene-propylene random terpolymer, which is a copolymer of styrene and 1-butene. Among these, an ethylene-propylene random copolymer is preferable.

  In the ethylene-propylene random copolymer and the acid-modified product thereof, the ethylene content is preferably 0.1 to 10% by mass, more preferably 1 to 7% by mass, and 2 to 5% by mass. Further preferred. When the ethylene content is 0.1% by mass or more, the effect of lowering the melting point by copolymerizing ethylene is sufficiently obtained, and the adhesion when the resin film for terminals is fused to a metal terminal at a low temperature tends to be improved. There is. When the ethylene content is 10% by mass or less, it is possible to suppress the melting point from being lowered too much, and the liquid leakage prevention property tends to be improved when the electricity storage device is held for a long time in a high temperature environment. The ethylene content can be calculated from the mixing ratio of monomers during polymerization.

  The melting point of the polyolefin random copolymer and the acid-modified product thereof is preferably 120 to 145 ° C, and more preferably 125 to 140 ° C. The weight average molecular weight of the polyolefin random copolymer and the acid-modified product thereof is preferably adjusted as appropriate so that the melting point is within this range, preferably 5,000 to 10,000,000, more preferably 10, 000 to 1,000,000. In addition, in this specification, a weight average molecular weight can be calculated | required by measuring by a gel permeation chromatography (GPC) and converting with the analytical curve using a standard polystyrene.

  The melt random flow rate (MFR) of the polyolefin random copolymer and the acid-modified product thereof is preferably 0.5 to 15 g / 10 min, and more preferably 1 to 10 g / 10 min. In addition, melt mass flow rate (MFR) can be calculated | required based on JISK7210.

  The terminal resin film 3 can be manufactured by a multilayer coextrusion molding method or a multilayer inflation molding method. Moreover, you may adhere | attach each layer 31,32,33 using an adhesive agent.

  Next, as the packaging material 2, a laminate having a layer structure as shown in FIG. 2 can be used. That is, the packaging material 2 shown in this figure includes an inner layer 21, an inner layer side adhesive layer 22, a corrosion prevention treatment layer 23, a barrier layer 24 that is a metal layer, and a corrosion layer from the inside that contacts the power storage device body 1. The prevention treatment layer 25, the outer layer-side adhesive layer 26, and the outer layer 27 have a seven-layer structure in which layers are sequentially laminated.

  As the base material of the inner layer 21, for example, a polyolefin resin or an acid-modified polyolefin resin obtained by graft-modifying maleic anhydride or the like on a polyolefin resin can be used. Examples of the polyolefin resin include low density, medium density, and high density polyethylene; ethylene-α olefin copolymer; homo, block, or random polypropylene; propylene-α olefin copolymer. These polyolefin resins may be used individually by 1 type, and may use 2 or more types together.

  Further, the inner layer 21 may be configured by using a single layer film or a multilayer film in which a plurality of layers are laminated according to a required function. Specifically, for example, in order to impart moisture resistance, a multilayer film in which a resin such as an ethylene-cyclic olefin copolymer or polymethylpentene is interposed may be used. Furthermore, the inner layer 21 may contain various additives (for example, a flame retardant, a slip agent, an antiblocking agent, an antioxidant, a light stabilizer, a tackifier, etc.), for example.

The thickness of the inner layer 21 is preferably such that the total of the thickness of the terminal resin film 3 and the thickness of the inner layer 21 is in the range of 30 to 300 μm. For example, it is preferably set within the range of 10 to 150 μm, but more preferably 30 to 80 μm. If the thickness of the inner layer 21 is less than 10 μm, the heat seal adhesion between the packaging materials 2 and the adhesion with the terminal resin film 3 may be reduced. Moreover, since it will become a factor of the cost increase of the packaging material 2 when the thickness of the inner layer 21 is thicker than 150 micrometers, it is not preferable.

  As the inner layer side adhesive layer 22, for example, a known adhesive such as a general dry lamination adhesive or an acid-modified heat-fusible resin can be appropriately selected and used.

  As shown in FIG. 2, the corrosion prevention treatment layers 23 and 25 are preferably formed on both surfaces of the barrier layer 24 in terms of performance. However, in consideration of cost, the barrier layer positioned on the inner layer adhesive layer 22 side. The corrosion prevention treatment layer 23 may be disposed only on the surface 24.

  The barrier layer 24 is a layer that prevents permeation of air and moisture. Examples of the material of the barrier layer 24 include aluminum and stainless steel, but aluminum is preferable from the viewpoint of cost, weight (density), and the like.

  As the outer layer side adhesive layer 26, for example, a general polyurethane adhesive mainly composed of polyester polyol, polyether polyol, acrylic polyol, or the like can be used.

  As the outer layer 27, for example, a single layer film such as nylon or polyethylene terephthalate (PET) or a multilayer film can be used. The outer layer 27 may include various additives (for example, a flame retardant, a slip agent, an antiblocking agent, an antioxidant, a light stabilizer, a tackifier, and the like), as with the inner layer 21. Further, the outer layer 27 may have a protective layer formed by laminating a resin insoluble in the electrolytic solution or coating a resin component insoluble in the electrolytic solution as a countermeasure against liquid leakage, for example. .

  When manufacturing an electrical storage device using the terminal resin film 3 according to the present invention, first, the terminal resin film 3 is overlapped such that the terminal heat-fusible resin layer 31 is in contact with both surfaces of the metal terminal 11. Adhere by hot pressing. In order to obtain sufficient adhesion and sealing property between the terminal resin film 16 and the metal terminal 14, it is desirable to heat and fuse the resin film 31 to a temperature equal to or higher than the melting point of the terminal heat-fusible resin layer 31. However, it is necessary that the temperature does not impair the insulating property of the heat-resistant insulating layer 32. For example, it is 140-170 degreeC.

  FIG. 3 shows a tab obtained by bonding the terminal resin film 3 to the metal terminal 11 in this manner. As can be seen from this figure, the terminal resin film 3 is disposed so as to cover a part of the outer peripheral surface of the metal terminal 11 and is liquid-tight and air-tight over the entire periphery including the upper and lower surfaces and side surfaces thereof. Sealed.

  In addition, it is desirable to use the metal terminal 11 in which the corrosion prevention layer 112 is formed on the surface of the metal terminal body 111. A metal can be used as the material of the metal terminal body 111. The metal used as the material of the metal terminal body 111 is preferably determined in consideration of the structure of the electricity storage device body 1 and the material of each component of the electricity storage device body 1.

For example, when the electricity storage device is a lithium ion secondary battery, aluminum is used as the positive electrode current collector, and copper is used as the negative electrode current collector. In this case, it is preferable to use aluminum as the material of the metal terminal body 111 connected to the positive electrode of the electricity storage device body 1. In consideration of corrosion resistance to the electrolytic solution, it is preferable to use, for example, an aluminum material having a purity of 97% or more such as 1N30 as the material of the metal terminal body 111 connected to the positive electrode of the electricity storage device body 1. Furthermore, when the metal terminal body 111 is bent, it is preferable to use an O material tempered by sufficient annealing for the purpose of adding flexibility. As a material of the metal terminal body 111 connected to the negative electrode of the electricity storage device body 1, it is preferable to use copper having a nickel plating layer formed on the surface or nickel.

  When the terminal resin film 3 is fused to the metal terminal 11, the molten terminal heat-fusible resin layer 31 wraps around the side surface of the metal terminal 11 and seals it in a liquid-tight and air-tight manner. It is desirable that the thickness is thin. 100 μm or less is sufficient, but 80 μm or less is desirable. In addition, when the thickness of the terminal heat-fusible resin layer 31 of the terminal resin film 3 is less than 25% of the thickness of the metal terminal 11, sealing of the side surface of the metal terminal 11 may be insufficient. .

The corrosion prevention layer 112 is disposed so as to cover the surface of the metal terminal body 111. In the case of a lithium ion secondary battery, a corrosive component such as LiPF ₆ is included in the electrolytic solution. The corrosion prevention layer 112 is a layer for suppressing the metal terminal body 111 from being corroded by a corrosive component such as LiPF ₆ contained in the electrolytic solution. The corrosion prevention layer 112 can be formed on the surface of the metal terminal body 111 by spraying, for example.

  Next, by electrically connecting one end portion of the metal terminal 11 to which the terminal resin film 3 is bonded in this way to the current collector of the electricity storage device main body 1, the packaging material 2 is arranged up and down and heat sealed. An electricity storage device can be manufactured.

Example 1
(1) Preparation of metal terminal 11 As the metal terminal main body 111, the thing of width 5mm, length 30mm, and thickness 60micrometer was used. The material was aluminum on the positive electrode side and nickel on the negative electrode side. Both positive and negative electrodes were subjected to non-chromium surface treatment. Both positive and negative electrodes were subjected to non-chromium surface treatment.

(2) Preparation of terminal resin film 3 An acid-modified polypropylene resin (modified PP) having a melting point of 145 ° C. and an MFR of 6.0 g / 10 min is used for the terminal heat-fusible resin layer 31, and the heat-resistant insulating layer 32 has a melting point. A polypropylene resin (PP) having an MFR of 1.3 g / 10 min at 165 ° C. was used. Resin film 3 for terminals was created by laminating the material resin of each layer by two types and two layers of inflation extrusion (hereinafter referred to as inflation method). The conditions of the inflation method are as follows: the melting temperature is 210 ° C., the blow ratio is 2.2, the terminal heat-fusible resin layer 31 has a thickness of 30 μm, and the heat-resistant insulating layer 32 has a thickness of 25 μm and a total thickness of 55 μm. So created.

(3) Creation of Tab As shown in FIG. 3, the terminal resin film 3 is overlapped so that the terminal heat-fusible resin layer 31 is in contact with both surfaces of the metal terminal 11, and heat fusion is performed at 155 ° C. for 10 seconds. I went to wear.

(4) Creation of packaging material 2 As packaging material 2, inner layer 21: polypropylene (thickness 40 μm), inner adhesive layer 22: acid-modified polypropylene, barrier layer 24: aluminum foil (A8079-O material), outer adhesive layer 26: Polyester polyol adhesive, outer layer 27: Nylon with a total thickness of 100 μm was used. A non-chromium surface treatment was performed on both surfaces of the aluminum foil to form corrosion prevention treatment layers 23 and 25.

(5) Preparation of battery pack for evaluation The size of the packaging material 2 main body packaging material is a rectangle of 50 mm × 90 mm, folded in half at the midpoint of the long side, and the positive electrode and the negative electrode are placed on one of the folded parts of 45 mm in length. 190 ° C across the tab
Heat sealing was performed for 5 seconds.

  The remaining sides were heat sealed at 190 ° C. for 3 seconds. First, the sides with a length of 50 mm are joined by heat sealing, and then 2 ml of an electrolyte solution obtained by adding lithium hexafluorophosphate to a mixed solution of diethyl carbonate and ethylene carbonate is filled. It was. As a result, a battery pack capable of tab evaluation, in which no power generation element was enclosed, was created.

(Examples 2-31 and Comparative Examples 1-5)
The material of the heat-resistant insulating layer 32, the heat-fusible resin layer 33 for packaging material, and the thickness of each layer were changed in various ways, and the metal terminals 11 of Examples 2-31 and Comparative Examples 1-5, and the resin film 3 for terminals. , Tabs and battery packs for evaluation were created.

  Table 1 summarizes the thicknesses of the layers of Examples 1 to 31 and Comparative Examples 1 to 6. The unit of thickness is “μm”.

なお、実施例２〜７は、二種二層構成の端子用樹脂フィルム３を使用したもので、端子用熱融着性樹脂層３１として実施例１と同じ融点１４５℃、ＭＦＲが６．０ｇ／１０ｍｉｎの酸変性ポリプロピレン樹脂（変性ＰＰ）を用い、耐熱性絶縁層３２として実施例１と同じ融点１６５℃、ＭＦＲが１．３ｇ／１０ｍｉｎのポリプロピレン樹脂（ＰＰ）を用いたものである。

In addition, Example 2-7 uses the resin film 3 for terminals of 2 types and 2 layers structure, and the melting | fusing point of 145 degreeC and MFR which are the same as Example 1 as the heat-fusible resin layer 31 for terminals are 6.0g. / 10 min acid-modified polypropylene resin (modified PP) is used, and the heat-resistant insulating layer 32 is made of the same melting point 165 ° C. and MFR 1.3 g / 10 min polypropylene resin (PP) as in Example 1.

  In Examples 8 to 9, three types and three layers of the resin film for terminal 3 are used, and the melting point is 145 ° C. and the MFR is used as the terminal heat-fusible resin layer 31 and the packaging material heat-fusible resin layer 33. Using 6.0 g / 10 min acid-modified polypropylene resin (modified PP) and heat-resistant insulating layer 32 using the same melting point 165 ° C. as in Example 1 and MFR 1.3 g / 10 min polypropylene resin (PP) It is.

  Example 10 uses a resin film 3 for a terminal having a two-type two-layer structure, and an acid having a melting point of 145 ° C. and an MFR of 6.0 g / 10 min as the terminal heat-fusible resin layer 31 as in Example 1. A modified polypropylene resin (modified PP) is used, and a polypropylene resin (PP) having the same melting point 165 ° C. and MFR 1.3 g / 10 min as in Example 1 is used as the heat-resistant insulating layer 32.

  Examples 11-17 use the resin film 3 for a terminal of 3 types and 3 layers structure, melting | fusing point 145 degreeC and MFR are as the heat-fusible resin layer 31 for terminals, and the heat-fusible resin layer 33 for packaging materials. A 6.0 g / 10 min acid-modified polypropylene resin (modified PP) is used, and the heat-resistant insulating layer 32 is the same melting point as in Example 1 at 165 ° C. and MFR 1.3 g / 10 min polypropylene resin (PP). is there.

  Example 18 uses a resin film 3 for a terminal having a three-layer / three-layer structure, and has a melting point of 145 ° C. and a MFR of 6.6 as the terminal heat-fusible resin layer 31 and the packaging material heat-fusible resin layer 33. A 0 g / 10 min acid-modified polypropylene resin (modified PP) is used, and a polypropylene resin (PP) having a melting point of 145 ° C. and an MFR of 5.5 g / 10 min is used as the heat-resistant insulating layer 32.

Example 19 uses a resin film 3 for a terminal having a three-layer / three-layer structure, and has a melting point of 145 ° C. and MFR of 6.5 as a terminal heat-fusible resin layer 31 and a packaging material heat-fusible resin layer 33. An acid-modified polypropylene resin (modified PP) of 0 g / 10 min is used, and a polypropylene resin (PP) having a melting point of 147 ° C. and an MFR of 1.7 g / 10 min is used as the heat-resistant insulating layer 32.

  Example 20 uses a resin film 3 for a terminal having a three-layer / three-layer structure, and has a melting point of 145 ° C. and an MFR of 6.6 as the terminal heat-fusible resin layer 31 and the packaging material heat-fusible resin layer 33. A 0 g / 10 min acid-modified polypropylene resin (modified PP) is used, and a polypropylene resin (PP) having a melting point of 163 ° C. and an MFR of 5.1 g / 10 min is used as the heat-resistant insulating layer 32.

  In Example 21, a resin film 3 for a terminal having a three-layer / three-layer structure was used. As the heat-fusible resin layer 31 for a terminal and the heat-fusible resin layer 33 for a packaging material, a melting point 145 ° C. and MFR 6. An acid-modified polypropylene resin (modified PP) of 0 g / 10 min was used, a polypropylene resin (PP) having a melting point of 145 ° C. and an MFR of 5.5 g / 10 min as a heat-resistant insulating layer 32, and alumina having an average particle diameter of 1 μm as a filler. A resin mixed by weight% is used.

  In Example 22, a resin film 3 for a terminal having a three-layer / three-layer structure was used, and the melting point was 145 ° C. and the MFR was 6.5 as the terminal heat-fusible resin layer 31 and the packaging material heat-fusible resin layer 33. Using 0 g / 10 min acid-modified polypropylene resin (modified PP), a resin in which 10% by weight of cellulose fiber is mixed with polypropylene resin (PP) having a melting point of 145 ° C. and MFR of 5.5 g / 10 min as the heat-resistant insulating layer 32. It is what was used.

  In Example 23, a resin film 3 for a terminal having a three-layer / three-layer structure was used. As the heat-fusible resin layer 31 for a terminal and the heat-fusible resin layer 33 for a packaging material, a melting point of 145 ° C. and an MFR of 6. A 0 g / 10 min acid-modified polypropylene resin (modified PP) is used, and a polyester resin (PET) having a melting point of 145 ° C. and an MFR of 5.5 g / 10 min is used as the heat-resistant insulating layer 32.

  Example 24 uses a resin film 3 for a terminal having a two-kind and two-layer structure. As a terminal heat-fusible resin layer 31, an acid having the same melting point 145 ° C. and MFR 6.0 g / 10 min as in Example 1 is used. A resin obtained by using a modified polypropylene resin (modified PP), a polypropylene resin (PP) having a melting point of 165 ° C. and an MFR of 1.3 g / 10 min as a heat-resistant insulating layer 32, and 5% by weight of silica having an average particle diameter of 3 μm as a filler. Is used.

  Example 25 uses a resin film 3 for a terminal having a two-kind and two-layer structure. As a terminal heat-fusible resin layer 31, an acid having a melting point of 145 ° C. and an MFR of 6.0 g / 10 min as in Example 1 is used. Using a modified polypropylene resin (modified PP), a resin obtained by mixing 3% by weight of cellulose fiber with a polypropylene resin (PP) having a melting point of 165 ° C. and an MFR of 1.3 g / 10 min as the heat-resistant insulating layer 32. .

  Example 26 uses a resin film 3 for a terminal having a two-kind and two-layer structure, and an acid having a melting point of 145 ° C. and an MFR of 6.0 g / 10 min as the terminal heat-fusible resin layer 31 as in Example 1. A modified polypropylene resin (modified PP) is used, and a polyester resin (PET) having a melting point of 165 ° C. and an MFR of 1.3 g / 10 min is used as the heat-resistant insulating layer 32.

  In Example 27, a resin film 3 for a terminal having a three-layer / three-layer structure is used, and the melting point is 145 ° C. and the MFR is 6.5 as the terminal heat-fusible resin layer 31 and the packaging material heat-fusible resin layer 33. A 0 g / 10 min acid-modified polypropylene resin (modified PP) is used, and a crosslinked acrylic resin (PMMA) having a melting point of 165 ° C. and an MFR of 1.3 g / 10 min is used for the heat-resistant insulating layer 32.

  In Example 28, a resin film 3 for a terminal having a three-kind / three-layer structure was used, and the melting point was 145 ° C. and the MFR was 6.5 as the terminal heat-fusible resin layer 31 and the packaging material heat-fusible resin layer 33. A 0 g / 10 min acid-modified polypropylene resin (modified PP) is used, a heat-resistant insulating layer 32 having a melting point of 165 ° C. and an MFR of 1.3 g / 10 min, and a sulfuric acid having an average particle size of 0.5 μm as a filler. A resin mixed with 1% by weight of barium is used.

  In Example 29, a terminal resin film 3 having a three-layer / three-layer structure was used, and an acid-modified polypropylene resin (modified PP) having a melting point of 145 ° C. and an MFR of 6.0 g / 10 min was applied to the terminal heat-fusible resin layer 31. ), A polypropylene resin (PP) having a melting point of 165 ° C. and an MFR of 1.3 g / 10 min is used for the heat-resistant insulating layer 32, and a melting point of 145 ° C. and an MFR of 6.0 g is used for the heat-fusible resin layer 33 for packaging materials. A resin prepared by mixing 5% by weight of alumina having an average particle diameter of 5 μm as a filler to a / 10 min acid-modified polypropylene resin (modified PP).

  Examples 30-31 used the resin film 3 for terminals of a 3 types, 3 layer structure, melting | fusing point 145 degreeC and MFR as the heat-fusible resin layer 31 for terminals, and the heat-fusible resin layer 33 for packaging materials A 6.0 g / 10 min acid-modified polypropylene resin (modified PP) is used, and the heat-resistant insulating layer 32 is the same melting point as in Example 1 at 165 ° C. and MFR 1.3 g / 10 min polypropylene resin (PP). is there.

  Each of Comparative Examples 1 to 5 uses a resin film 3 for a terminal having a two-type and two-layer structure, and the same melting point 145 ° C. and MFR 6. An acid-modified polypropylene resin (modified PP) of 0 g / 10 min is used, and a polypropylene resin (PP) having a melting point of 165 ° C. and MFR of 1.3 g / 10 min as in Example 1 is used as the heat-resistant insulating layer 32.

(Evaluation)
For Examples 1 to 31 and Comparative Examples 1 to 5, when the battery pack for evaluation was sealed, the insulation resistance of the terminal resin film 3, and the terminal resin film 3 was thermally fused to the metal terminal 11 to form a tab The insulation resistance of the terminal resin film 3, the insulation resistance of the terminal resin film 3 when the evaluation battery pack was prepared, and the presence or absence of curling of the terminal resin film 3 were evaluated. Evaluation methods and evaluation criteria are as follows.

[Sealability of battery pack for evaluation]
The number of samples is 100. Among these 100 samples, 95 or more samples without lamination or leakage are “◎”, 90 to less than 95 “◯”, 80 to less than 90 The case was evaluated as “Δ”, and the case of less than 80 was evaluated as “×”.

[Insulation resistance of resin film for terminal 3 alone]
A terminal was brought into contact with the front and back of the resin film 3 for terminal, and the one having an insulation resistance between terminals of 25 MΩ or more was determined to be OK. The number of samples is 100. Among these 100 samples, OK is 95 or more, “「 ”, 90 to less than 95,“ ◯ ”, 80 to less than 90 “Δ”, when less than 80, “×” was evaluated.

[Insulation resistance of tab-shaped resin film 3 for terminals]
After the terminal resin film 3 is thermally fused to the metal terminal 11 to form a tab, the terminal is brought into contact with both the surface of the terminal resin film 3 and the metal terminal 11 so that the insulation resistance between the terminals is 25 MΩ or more. The one was OK. The number of samples is 100. Among these 100 samples, OK is 95 or more, “「 ”, 90 to less than 95,“ ◯ ”, 80 to less than 90 “Δ”, when less than 80, “×” was evaluated.

[Insulation Resistance of Resin Film 3 for Battery Type Terminal]
The terminals were brought into contact with both the surface of the packaging material 2 of the evaluation battery pack and the metal terminal 11 of the positive electrode, and those having an insulation resistance of 25 MΩ or more between the terminals were determined to be OK. The number of samples is 100. Among these 100 samples, OK is 95 or more, “「 ”, 90 to less than 95,“ ◯ ”, 80 to less than 90 “Δ”, when less than 80, “×” was evaluated.

[Presence or absence of curling of resin film 3 for terminals]
When the terminal resin film 3 is cut into a strip having a width of 5 mm and a length of 300 mm to make a sample, and the sample is hung by its own weight, the lower end is in a position within 30 mm in the horizontal direction from the upper end. The case where the curl was larger than 30 mm was evaluated as “x”.

  The results are shown in Table 2.

（考察）
以上の結果から、耐熱性絶縁層の厚さｔ３２を端子用熱融着性樹脂層３１の厚さｔ３１で割った値ｔ３２／ｔ３１が、０．１０（実施例４〜６,１３）〜１．００（実施例２〜３,８，３１）の端子用樹脂フィルムを使用して電池を作成すると、密封性及び電気絶縁性のいずれについても優れていることが分かる。これに対して、ｔ３２／ｔ３１が０．０７の比較例１では密封性が劣り、また、電池を構成したときの電気絶縁性も劣っている。また、ｔ３２／ｔ３１が１．０を越える場合（実施例２〜５）の場合にも、密封性が劣っており、これに加えて、総厚が１２μｍの比較例５では電気絶縁性も劣っている。

(Discussion)
From the above results, a value t32 / t31 obtained by dividing the thickness t32 of the heat-resistant insulating layer by the thickness t31 of the terminal heat-fusible resin layer 31 is 0.10 (Examples 4 to 6, 13) to 1 When a battery is made using a terminal resin film of 0.000 (Examples 2-3, 8, 31), it can be seen that both the sealing property and the electrical insulation property are excellent. On the other hand, in Comparative Example 1 where t32 / t31 is 0.07, the sealing performance is inferior, and the electrical insulation when the battery is configured is also inferior. In addition, when t32 / t31 exceeds 1.0 (Examples 2 to 5), the sealing performance is inferior. In addition, in Comparative Example 5 having a total thickness of 12 μm, the electrical insulation is also inferior. ing.

  From this result, in order to achieve both sealing performance and electrical insulation, the terminal resin film 3 in which the t32 / t31 is in the range of 0.10 to 1.00 and the total thickness is 15 μm or more. Can be understood.

1: Power storage device body 11: Metal terminal 111: Metal terminal body 112: Corrosion prevention layer 2: Packaging material 21: Inner layer 22: Inner layer side adhesive layer 23: Corrosion prevention treatment layer 24: Barrier layer 25: Corrosion prevention treatment layer 26 : Outer layer side adhesive layer 27: Outer layer 2a: Seal part 3: Resin film for terminal 31: Heat-sealable resin layer for terminal 32: Heat-resistant insulating layer 33: Heat-sealable resin layer for packaging material

Claims (9)

A resin film for terminals that covers a part of the outer peripheral surface of a metal terminal of an electricity storage device, comprising a heat-fusible resin layer that adheres to the metal terminal, and a heat-resistant insulating layer, and the following conditions The resin film for terminals characterized by satisfying 1-3.
Condition 1: The electricity storage device satisfies the following conditions 1a to 1c.
Condition 1a: It is configured to include three members: a power storage device body, a packaging material, and a terminal resin film.
Condition 1b: The packaging material disposed on the upper and lower surfaces of the electricity storage device body is sealed and sealed around the electricity storage device body.
Condition 1c: The metal terminal extends from the sealing surface of the packaging material to the outside, and the metal terminal and the packaging material are sealed via a resin film for terminals.
Condition 2: The thickness of the heat-resistant insulating layer is not more than the thickness of the heat-fusible resin layer and not less than 0.1 times the thickness of the heat-fusible resin layer.
Condition 3: The total thickness of the terminal resin film is 15 μm or more.   The terminal resin film according to claim 1, comprising two layers of a heat-fusible resin layer and a heat-resistant insulating layer.   2. The terminal according to claim 1, further comprising a heat-fusible resin layer for a packaging material laminated on the heat-resistant insulating layer side in addition to the two layers of the heat-fusible resin layer and the heat-resistant insulating layer. Resin film.   4. The resin film for terminals according to claim 3, wherein the thickness of the heat-fusible resin layer for packaging material is equal to or thinner than that of the heat-fusible resin layer.   Total resin thickness is 60 micrometers or less, The resin film for terminals in any one of Claims 1-4 characterized by the above-mentioned.   A tab comprising: the metal terminal; and a resin film for a terminal according to any one of claims 1 to 5 disposed so as to cover a part of an outer peripheral surface of the metal terminal.   The tab according to claim 6, wherein the thickness of the metal terminal is 80 μm or less.   The tab according to claim 6 or 7, wherein the thickness of the heat-fusible resin layer is 25 to 100% of the thickness of the metal terminal.   An electrical storage device comprising the tab according to claim 6.

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