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US-12626980-B2 - Adhesive film for metal terminal, method for producing adhesive film for metal terminal, metal terminal with adhesive film for metal terminal attached thereto, power storage device, and method for producing power storage device

US12626980B2US 12626980 B2US12626980 B2US 12626980B2US-12626980-B2

Abstract

An adhesive film for a metal terminal, interposed between a metal terminal electrically connected to an electrode of a power storage device element and a power storage device packaging material for sealing the power storage device element, wherein the adhesive film for a metal terminal includes a laminate sequentially including a first polyolefin layer on the metal terminal side, a base material, and a second polyolefin layer on the power storage device packaging material side, the laminate has a first adhesive layer between the first polyolefin layer and the base material, a second adhesive layer between the second polyolefin layer and the base material, or both the first adhesive layer and the second adhesive layer, the base material has a melting peak temperature of 135° C. or more, and at least one of the first adhesive layer and the second adhesive layer has a melting peak temperature of 100° C. or less.

Inventors

  • Shinji Hayashi
  • Yoichi Mochizuki

Assignees

  • DAI NIPPON PRINTING CO., LTD.

Dates

Publication Date
20260512
Application Date
20210401
Priority Date
20200402

Claims (12)

  1. 1 . An adhesive film for a metal terminal, which is to be interposed between a metal terminal electrically connected to an electrode of a power storage device element and a power storage device packaging material for sealing the power storage device element, wherein the adhesive film for a metal terminal comprises a laminate sequentially including a first polyolefin layer disposed on the metal terminal side, a base material, and a second polyolefin layer disposed on the power storage device packaging material side, the laminate has a first adhesive layer between the first polyolefin layer and the base material, has a second adhesive layer between the second polyolefin layer and the base material, or has both the first adhesive layer and the second adhesive layer, the base material contains a polyolefin backbone and has a melting peak temperature of 135° C. or more, and at least one of the first adhesive layer and the second adhesive layer has a melting peak temperature of 100° C. or less.
  2. 2 . The adhesive film for a metal terminal according to claim 1 , wherein the base material has a surface hardness of 15 N/mm 2 or more, as measured in an environment at a temperature of 110° C.
  3. 3 . The adhesive film for a metal terminal according to claim 1 , wherein each of the first adhesive layer and the second adhesive layer has a melting peak temperature of 100° C. or less.
  4. 4 . The adhesive film for a metal terminal according to claim 1 , wherein at least one of the first polyolefin layer and the second polyolefin layer contains an acid-modified polyolefin.
  5. 5 . The adhesive film for a metal terminal according to claim 1 , wherein each of the first adhesive layer and the second adhesive layer is a cured product of a resin composition containing an acid-modified polyolefin and a curing agent.
  6. 6 . A metal terminal with an adhesive film for a metal terminal attached thereto, comprising the adhesive film for a metal terminal according to claim 1 , wherein the adhesive film for a metal terminal is attached to the metal terminal.
  7. 7 . A power storage device comprising a power storage device element comprising at least a positive electrode, a negative electrode, and an electrolyte, a power storage device packaging material for sealing the power storage device element, and the metal terminal electrically connected to each of the positive electrode and the negative electrode and protruding outside the power storage device packaging material, wherein the adhesive film for a metal terminal according to claim 1 is interposed between the metal terminal and the power storage device packaging material.
  8. 8 . A method for producing a power storage device comprising the power storage device element comprising at least a positive electrode, a negative electrode, and an electrolyte, the power storage device packaging material for sealing the power storage device element, and the metal terminal electrically connected to each of the positive electrode and the negative electrode and protruding outside the power storage device packaging material, the method comprising the step of interposing the adhesive film for a metal terminal according to claim 1 between the metal terminal and the power storage device packaging material, and sealing the power storage device element with the power storage device packaging material.
  9. 9 . A method for producing an adhesive film for a metal terminal, which is to be interposed between a metal terminal electrically connected to an electrode of a power storage device element and a power storage device packaging material for sealing the power storage device element, wherein the adhesive film for a metal terminal comprises a laminate sequentially including a first polyolefin layer disposed on the metal terminal side, a base material, and a second polyolefin layer disposed on the power storage device packaging material side, and the laminate has a first adhesive layer between the first polyolefin layer and the base material, has a second adhesive layer between the second polyolefin layer and the base material, or has both the first adhesive layer and the second adhesive layer, the method comprising the step of obtaining the laminate sequentially including the first polyolefin layer, the base material, and the second polyolefin layer, wherein the base material contains a polyolefin backbone and has a melting peak temperature of 135° C. or more, and at least one of the first adhesive layer and the second adhesive layer has a melting peak temperature of 100° C. or less.
  10. 10 . A power storage device comprising a power storage device element comprising at least a positive electrode, a negative electrode, and an electrolyte, a power storage device packaging material for sealing the power storage device element, and the metal terminal electrically connected to each of the positive electrode and the negative electrode and protruding outside the power storage device packaging material, wherein an adhesive film for a metal terminal is interposed between the metal terminal and the power storage device packaging material, the adhesive film for a metal terminal comprises a laminate sequentially including a first polyolefin layer disposed on the metal terminal side, a base material containing a polyolefin backbone and the base material has a melting peak temperature of 135° C. or more, and a second polyolefin layer disposed on the power storage device packaging material side, the laminate has a first adhesive layer between the first polyolefin layer and the base material, has a second adhesive layer between the second polyolefin layer and the base material, or has both the first adhesive layer and the second adhesive layer, and the power storage device opens from a position where the first adhesive layer or the second adhesive layer of the adhesive film for a metal terminal is laminated, in an environment at a temperature of 100° C. or more and 130° C. or less.
  11. 11 . A power storage device comprising a power storage device element comprising at least a positive electrode, a negative electrode, and an electrolyte, a power storage device packaging material for sealing the power storage device element, and the metal terminal electrically connected to each of the positive electrode and the negative electrode and protruding outside the power storage device packaging material, wherein an adhesive film for a metal terminal is interposed between the metal terminal and the power storage device packaging material, the adhesive film for a metal terminal comprises a laminate sequentially including a first polyolefin layer disposed on the metal terminal side, a base material, and a second polyolefin layer disposed on the power storage device packaging material side, the laminate has a first adhesive layer between the first polyolefin layer and the base material, has a second adhesive layer between the second polyolefin layer and the base material, or has both the first adhesive layer and the second adhesive layer, the base material contains a polyolefin backbone and has a melting peak temperature of 135° C. or more, at least one of the first adhesive layer and the second adhesive layer has a melting peak temperature of 100° C. or less, the power storage device packaging material comprises a laminate including at least a base material layer, a barrier layer, and a heat-sealable resin layer, and the heat-sealable resin layer has a melting peak temperature of 130° C. or more.
  12. 12 . A power storage device packaging material for use in a power storage device, wherein the power storage device comprises a power storage device element comprising at least a positive electrode, a negative electrode, and an electrolyte, the power storage device packaging material for sealing the power storage device element, and the metal terminal electrically connected to each of the positive electrode and the negative electrode and protruding outside the power storage device packaging material, and wherein an adhesive film for a metal terminal is interposed between the metal terminal and the power storage device packaging material, and the adhesive film for a metal terminal comprises a laminate sequentially including a first polyolefin layer disposed on the metal terminal side, a base material, and a second polyolefin layer disposed on the power storage device packaging material side, and the adhesive film for a metal terminal has a function of opening from a position where a first adhesive layer or a second adhesive layer of the adhesive film for a metal terminal is laminated, in an environment at a temperature of 100° C. or more and 130° C. or less, the power storage device packaging material comprising a laminate including at least a base material layer, a barrier layer, and a heat-sealable resin layer, wherein the heat-sealable resin layer has a melting peak temperature that is 130° C. or more and higher than a melting peak temperature of the first polyolefin layer of the adhesive film for a metal terminal, wherein the base material contains a polyolefin backbone and has a melting peak temperature of 135° C. or more.

Description

TECHNICAL FIELD The present disclosure relates to an adhesive film for a metal terminal, a method for producing the adhesive film for a metal terminal, a metal terminal with the adhesive film for a metal terminal attached thereto, a power storage device, and a method for producing the power storage device. BACKGROUND ART Various types of power storage devices have been heretofore developed, and in every power storage device, a power storage device packaging material is an essential member for sealing a power storage device element including electrodes and an electrolyte. Metallic power storage device packaging materials have been heretofore widely used as power storage device packaging materials. In recent years, however, along with improvements in the performance of electric cars, hybrid electric cars, personal computers, cameras, mobile phones, and the like, power storage devices have been required to be diversified in shape, and to be thinner and lighter weight. However, the widely used metallic power storage device packaging materials are disadvantageous in that they have difficulty in keeping up with the diversification of shapes, and are limited in weight reduction. Thus, a laminated sheet in which a base material layer/an adhesive layer/a barrier layer/a heat-sealable resin layer are sequentially laminated has been recently proposed as a power storage device packaging material that can be readily processed into various shapes, and can achieve a thickness reduction and a weight reduction. When such a laminated film-shaped power storage device packaging material is used, a power storage device element is sealed with the power storage device packaging material by heat-sealing a peripheral region of the power storage device packaging material in a state wherein the heat-sealable resin layers, positioned as the innermost layers of the power storage device packaging material, are opposed to each other. Metal terminals protrude from the heat-sealed region of the power storage device packaging material, and the power storage device element sealed with the power storage device packaging material is electrically connected to the outside via the metal terminals electrically connected to the electrodes of the power storage device element. That is, in the heat-sealed region of the power storage device packaging material, the region where each of the metal terminals is present is heat-sealed with the metal terminal being held between the heat-sealable resin layers. Because the metal terminal and the heat-sealable resin layer are formed of different types of materials, the adhesion is likely to decrease at the interface between the metal terminal and the heat-sealable resin layer. Thus, an adhesive film may be disposed between the metal terminal and the heat-sealable resin layer, for the purpose of improving the adhesion between these layers, for example. An example of this adhesive film is disclosed in, for example, Patent Literature 1. CITATION LIST Patent Literature Patent Literature 1: JP-A-2015-79638Patent Literature 2: JP-A-2002-8616 SUMMARY OF INVENTION Technical Problem In recent years, as smartphones have enabled faster and larger volumes of data communication, the amount of electricity consumed has also increased, and thus, research to increase the capacity of power storage devices has been conducted. However, increasing the battery capacity increases the container size and the amount of reactive substances, and also increases the amount of gas generated in the event of thermal runaway of the power storage device (i.e., in the event of a temperature rise in the power storage device), leading to an increased risk of explosion due to an increase in internal pressure of the power storage device. Power storage devices (for example, metal can batteries) produced using metallic packaging materials may be provided with a safety valve to ensure safety in the event of gas generation (see Patent Literature 2). However, it is difficult to provide this safety valve in power storage devices produced using laminated film-shaped packaging materials. Thus, there is an issue of avoiding expansion of such a power storage device due to gas generated inside the power storage device when heated to a high temperature. Under such circumstances, it is a main object of the present disclosure to provide an adhesive film for a metal terminal, which is to be interposed between a metal terminal electrically connected to an electrode of a power storage device element and a power storage device packaging material for sealing the power storage device element, which adhesive film for a metal terminal allows the metal terminal of the power storage device and a heat-sealable resin layer of the power storage device packaging material to adhere to each other until the power storage device is heated to a high temperature (for example, 100 to 130° C., preferably 110 to 130° C., particularly preferably 120 to 130° C.), and allows the power stor