JP5286730B2 - Flat electrochemical cell - Google Patents

Description

  The present invention relates to a flat electrochemical cell that exhibits stable sealing and insulating properties even when a peripheral edge of a thermally bonded packaging material is bent.

A lithium ion battery, which is an example of a flat electrochemical cell, is also referred to as a lithium secondary battery, and includes a liquid, gel-like or polymer polymer electrolyte, and a cathode / negative electrode active material comprising a polymer polymer. . In this lithium ion battery, the lithium atom (Li) in the lithium transition metal oxide, which is the positive electrode active material, is charged as lithium ion (Li ⁺ ) during charging and enters the carbon layer of the negative electrode (intercalation). This is a battery in which charge / discharge reaction proceeds when ions (Li ⁺ ) are separated from the carbon layer (deintercalation) and move to the positive electrode to become the original lithium compound. From the nickel-cadmium battery and the nickel-hydrogen battery The output voltage is high, the energy density is high, and the apparent discharge capacity is reduced by repeating shallow discharge and recharging, so that there is no so-called memory effect.

  In addition, the configuration of the lithium ion battery generally includes a positive electrode current collector (aluminum, nickel) / positive electrode active material layer (polymer positive electrode material such as metal oxide, carbon black, metal sulfide, electrolyte, polyacrylonitrile) / Electrolyte layer (carbonate electrolyte such as propylene carbonate, ethylene carbonate, dimethyl carbonate, ethylene methyl carbonate, inorganic solid electrolyte composed of lithium salt, gel electrolyte, etc.) / Negative electrode active material layer (lithium metal, alloy, carbon, electrolyte, Lithium ion battery main body (corresponding to the flat electrochemical cell main body of the present invention) composed of a polymer negative electrode material such as polyacrylonitrile) / negative electrode current collector (copper, nickel, stainless steel) and a lithium ion battery main body are packaged Made of packaging material.

  Since the packaging material is flexible and can be designed freely, a laminate in which a base material layer, a metal layer as a metal foil layer, and a heat-adhesive resin layer are sequentially laminated is suitable as a packaging material in recent years. Tend to be used. Moreover, according to the packaging method of a lithium ion battery main body, it can be divided into a plurality of types. FIG. 7 is a perspective view of a pouch-type lithium ion battery 101 using a bag-shaped packaging material, and FIG. 8 is a perspective view showing a state in which the lithium ion battery 101 of FIG. 7 is disassembled. As shown in FIGS. 7 and 8, the pouch-type lithium ion battery 101 is composed of a lithium ion battery main body 102 and a packaging material 105, and the lithium ion battery main body 102 accommodated in the packaging material 105 is a package of the lithium ion battery main body 102. By sealing the material peripheral portion 105c, the packaging material 105 is hermetically sealed, and the moisture resistance inside is ensured.

  FIG. 9 is a perspective view of an embossed type lithium ion battery 101, and FIG. 10 is a perspective view showing a state in which the lithium ion battery 101 of FIG. 9 is disassembled. As shown in FIGS. 9 and 10, the embossed type lithium ion battery 101 includes a packaging material 110 that is formed by stacking a laminated body composed of a tray 110 a on which an embossed portion is formed and a sheet 110 b. Further, the lithium ion battery main body 102 is housed in the tray 110a, the tray 110a is closed with a sheet 110b, the packaging material peripheral edge portion 110c is overlapped, and the packaging material peripheral edge portion 110c is heat-sealed. Is hermetically sealed in the packaging material 110. In any type of packaging method, the lithium ion battery 101 is sandwiched between the packaging material 110 with the battery tab 104 of the lithium ion battery main body 102 protruding outward.

  FIG. 11 is a perspective view showing the lithium ion battery 101 housed in the plastic case 150. As shown in FIG. 11, normally, the lithium ion battery 101 is housed and used in a plastic case 150 in order to protect the lithium ion battery 101 from an external impact. At this time, as shown in Patent Document 1 or Patent Document 2, in order to increase the capacity per volume of the lithium ion battery 101 and improve the volumetric efficiency, the heat-sealed packaging material peripheral portion 110c is bent to form a plastic case. Store in 150. However, the heat-adhesive resin layer constituting the heat-sealed packaging material peripheral portion 110c is once melted by heat sealing and then recrystallized. For this reason, when an excessive load is applied to the heat-adhesive resin layer, cracks are likely to occur. Therefore, in this folding process, cracks are particularly likely to occur in the heat-adhesive resin layer, and the electrolyte hermetically sealed in the packaging material 110 may come into contact with the metal foil layer through the crack, and the metal foil layer may be energized. It was. And it has been a problem that the output of the lithium ion battery 101 is remarkably lowered.

In addition to housing the lithium ion battery main body 102 in the packaging material 110, the same problem occurs when the capacitor and the electric double layer capacitor are housed in the packaging material 110 and hermetically sealed.
JP 2002-319374 A JP 2002-319375 A

  Accordingly, in view of the above problems, the present invention is to provide a flat electrochemical cell such as a lithium ion battery having high durability and high safety that ensures hermeticity even after long-term use.

  In order to achieve the above object, the flat electrochemical cell of the present invention is formed by laminating a laminate in which a base material layer, a metal foil layer, and a thermoadhesive resin layer are at least sequentially laminated. A flat electrochemical cell including a positive electrode composed of a positive electrode active material and a positive electrode current collector, a negative electrode composed of a negative electrode active material and a negative electrode current collector, and an electrolyte filled between the positive electrode and the negative electrode inside the packaging material The main body is housed, the tip of the tab connected to the negative electrode and the positive electrode is protruded to the outside of the packaging material, the peripheral portion of the packaging material is thermally bonded, and the flat electrochemical cell body is disposed inside the packaging material. A flat-type electrochemical cell that is bent at the peripheral edge of the packaging material, and the bending direction of the peripheral edge of the packaging material is the flow direction (MD direction) of the resin constituting the thermoadhesive resin layer And stack the laminates so that Characterized in that wherein the allowed.

  According to this configuration, the volume efficiency of the flat electrochemical cell can be improved by bending the peripheral edge of the packaging material of the flat electrochemical cell. In addition, the resin constituting the heat-adhesive resin layer is less likely to crack with respect to bending in the MD direction even after recrystallization after heat bonding. Therefore, the laminates are overlapped and flattened so that the flow direction (MD direction) of the resin constituting the thermoadhesive resin layer of the packaging material is substantially the same as the direction in which the peripheral edge of the thermally bonded packaging material is bent. By providing a flat electrochemical cell, it is possible to provide a flat electrochemical cell that prevents cracking of the thermoadhesive resin layer due to bending of the peripheral edge of the packaging material, and ensures hermeticity even during long-term use. It becomes possible.

  In the flat electrochemical cell having the above-described configuration, the pull-out direction of the tab and the flow direction (MD direction) of the resin constituting the thermoadhesive resin layer are substantially orthogonal.

  According to this configuration, the thermoadhesive resin is formed by overlapping the laminate so that the flow direction (MD direction) of the resin constituting the thermoadhesive resin layer of the packaging material is substantially orthogonal to the pulling-out direction of the tab. The area | region of the packaging material peripheral part which can be bend | folded in the same direction as the flow direction (MD direction) of resin which comprises a layer can be ensured widely. By configuring the packaging material of the flat electrochemical cell in this way, it prevents the occurrence of cracks in the heat-adhesive resin layer due to the folding of the peripheral edge of the packaging material, while ensuring the sealing property even for long-term use. The volumetric efficiency of the electrochemical cell can be improved.

  The present invention also relates to a flat electrochemical cell having the above-described configuration, wherein the laminate has a recess formed by press working, and the flat electrochemical cell body is accommodated in the recess. The concave portion is formed in a rectangular parallelepiped shape, and the longitudinal direction of the concave portion and the flow direction (MD direction) of the resin constituting the thermoadhesive resin layer are substantially orthogonal.

  According to this configuration, in the embossed-type flat electrochemical cell in which the flat electrochemical cell main body is housed in the concave portion formed by pressing the laminate, the longitudinal direction of the rectangular parallelepiped concave portion and the thermoadhesive resin layer are provided. Since the flow direction (MD direction) of the constituting resin is substantially orthogonal, the flow direction (MD direction) of the resin constituting the heat-adhesive resin layer at the long side portion of the four-side packaging material peripheral portion formed in the recess. ) In the same direction. Therefore, it is possible to improve the volume efficiency of the embossed flat electrochemical cell while preventing cracking of the heat-adhesive resin layer due to bending of the peripheral edge of the packaging material and ensuring hermeticity even during long-term use. it can.

  The present invention is a flat electrochemical cell that prevents the occurrence of cracks in the heat-adhesive resin layer due to bending of the peripheral edge of the packaging material, and can improve the volumetric efficiency while ensuring the sealing performance even during long-term use. is there. The configuration will be described in more detail with reference to the drawings.

  FIG. 1 is a cross-sectional view showing a laminated structure of a packaging material 10 constituting the flat electrochemical cell 1 of the present invention. As shown in FIG. 1, the laminate of the packaging material 10 according to the present invention has a base material layer 6 as an outermost layer, a heat-adhesive resin layer 8 as an innermost layer, and a metal foil layer 7 disposed therebetween. . At this time, by providing the chemical conversion treatment layer 7 a on the surface of the metal foil layer 7, the interlayer adhesive strength between the base material layer 6 and the heat-adhesive resin layer 8 and the metal foil layer 7 is further stabilized.

  Here, as a method of laminating the metal foil layer 7 and the heat-adhesive resin layer 8 in the outer package 10 according to the present invention, there are a dry lamination method, a thermal lamination method, a sandwich lamination method, and the like. The resin constituting the heat-adhesive resin layer 8 has a predetermined flow direction (MD direction). Here, even after the thermal adhesive resin layer 8 is recrystallized after thermal bonding, cracks hardly occur with respect to bending in the MD direction. Therefore, the present invention configures the packaging material so that the folding direction of the thermally bonded packaging material peripheral edge portion 10c matches the MD direction of the thermal adhesive resin layer 8.

  2-7 is a figure which shows the manufacturing process of the pouch type flat electrochemical cell 1 which concerns on this invention. With reference to FIGS. 2-7, the manufacturing process of the flat type electrochemical cell based on this invention is demonstrated. First, as shown in FIG. 2, a long belt-like hoop material (laminated body) 10 is prepared. At this time, the hoop material (laminate) 10 has the laminated structure shown in FIG. 1, and the innermost thermal adhesive resin layer 8 has the MD direction in the longitudinal direction of the hoop material 10. Next, as shown in FIG. 3, the hoop material is press-formed into a predetermined shape at predetermined intervals along the longitudinal direction to form the tray portion 10a. At this time, the tray part 10 a is formed in a rectangular parallelepiped shape, and the longitudinal direction of the tray part 10 a is formed in a direction orthogonal to the MD direction of the thermoadhesive resin layer 8. Next, as shown in FIG. 4, the adjacent tray portions 10 a are cut leaving a predetermined width, and the stacked body 10 is separated. At this time, the laminated body 10 has a configuration in which the sheet portion 10b is continuously provided in a region other than the tray portion 10a, and a configuration in which a packaging material peripheral portion 10c serving as a seal region is also provided continuously at the periphery of the tray portion 10a. It becomes. Next, as shown in FIG. 5, the flat electrochemical cell main body 2 is accommodated in the tray portion 10a, the connecting portion of the sheet portion 10b and the tray portion 10a is bent, and the tray portion 10a is closed. At this time, as shown in FIG. 6, the tab 4 connected to the positive electrode and the negative electrode of the flat electrochemical main body 2 is sandwiched by the sheet portion 10b and the peripheral portion of the tray portion 10a from one short side of the tray portion 10b. Thus, the tip protrudes outside the packaging material 10. And the peripheral part 10c of the packaging material 10 is heat-sealed, and the flat type electrochemical cell main body 2 is sealed and accommodated in the packaging material 10 inside. At this time, the pull-out direction of the tab 4 and the direction of the thermal adhesive resin layer 8MD are substantially orthogonal. Therefore, the volume efficiency of the flat electrochemical cell 1 can be increased by bending the two long sides of the packaging material peripheral edge portion 10c in the MD direction. The thermal adhesive resin layer 8 is least prone to crack when bent in the MD direction. Therefore, the flat electrochemical cell 1 according to the present invention prevents cracking of the thermoadhesive resin layer 8 due to bending of the peripheral edge portion 10c of the packaging material in the MD direction, while ensuring the sealing performance even in long-term use, The volume efficiency of the embossed flat electrochemical cell 1 can be improved.

  The present invention is not limited to the embossed flat electrochemical cell, but can be applied to all electrochemical cells. For example, a pouch-shaped packaging material is configured so that the MD direction of the thermal bonding resin layer is substantially orthogonal to the pulling-out direction of the tab, and the packaging material peripheral portion 10c is bent in the same direction as the MD direction. Like the flat electrochemical cell 1, the pouch-type flat electrochemical cell prevents cracking of the thermoadhesive resin layer 8 due to bending of the peripheral edge portion 10c of the packaging material, and ensures sealing performance even in long-term use. The volume efficiency of the cell 1 can be improved.

  As described above, the packaging material 10 is formed by overlapping the laminate so that the folding direction of the peripheral edge of the packaging material is substantially the same as the flow direction (MD direction) of the resin constituting the heat-adhesive resin layer 8, and the flat type By producing the electrochemical cell 1, it is possible to provide a flat electrochemical cell that prevents cracking of the heat-adhesive resin layer 8 due to bending of the peripheral edge portion 10c of the packaging material, and ensures hermeticity even during long-term use. It becomes possible.

  Further, by forming the packaging material 10 by stacking the laminate so that the flow direction (MD direction) of the resin constituting the thermal adhesive resin layer 8 of the packaging material is substantially orthogonal to the pulling-out direction of the tab Further, it is possible to ensure a wide area of the peripheral edge portion 10c of the packaging material that can be bent in the same direction as the flow direction (MD direction) of the resin constituting the thermal adhesive resin layer 8.

  Further, in the embossed flat electrochemical cell 1 in which the flat electrochemical cell main body 2 is accommodated in the concave portion 10a formed by pressing the laminate, the longitudinal direction of the rectangular parallelepiped concave portion 10a and the thermoadhesive resin layer Of the four sides of the packaging material peripheral portion 10c formed in the recess 10a by forming the packaging material 10 by overlapping the laminate so that the flow direction (MD direction) of the resin constituting 8 is substantially orthogonal to each other. The long side portion can be bent in the same direction as the flow direction (MD direction) of the resin constituting the heat-adhesive resin layer 8. Therefore, it is possible to prevent the occurrence of cracks in the thermal adhesive resin layer 8 due to the bending of the peripheral edge portion 10c of the packaging material, and to improve the volumetric efficiency of the embossed flat electrochemical cell 1 while ensuring the sealing performance even during long-term use. Can be planned.

  Next, each layer of the outer package 10 shown in FIG. 1 will be specifically described. The heat-adhesive resin layer 8 is used to seal the metal terminal between the heat-adhesive resin layer 8 and the metal terminal 4 when the metal terminal 4 of the lithium battery body 2 is sandwiched in a state of protruding outward and thermally bonded. The type of polypropylene layer to be constructed differs depending on whether or not a conductive film is interposed. When an adhesive film for sealing metal terminals is interposed, a film made of a propylene-based resin alone or a mixture may be used. When an adhesive film for sealing metal terminals is not interposed, graft modification with unsaturated carboxylic acid is performed. It is necessary to use a film made of the acid-modified olefin resin.

  Polypropylene is preferably used as the heat-adhesive resin layer 8, but a single layer or a multilayer of linear low density polyethylene or medium density polyethylene, or a single resin composed of a blend resin of linear low density polyethylene or medium density polyethylene. Films consisting of layers or multilayers can also be used.

  Next, the base material layer 6 will be described. The base material layer 6 is generally made of stretched polyester or nylon film. At this time, examples of the polyester resin include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, copolymerized polyester, and polycarbonate. . Examples of nylon include polyamide resin, that is, nylon 6, nylon 6,6, a copolymer of nylon 6 and nylon 6,6, nylon 6,10, polymetaxylylene adipamide (MXD6), and the like.

  Next, the metal foil layer 7 will be described. The metal foil layer 7 is a layer for preventing water vapor from entering the inside of the lithium ion battery from the outside, and stabilizes the pinhole and processability (pouching, embossing formability) of the metal foil layer alone, In order to provide pinhole resistance, a metal such as aluminum or nickel having a thickness of 15 μm or more, or a film on which an inorganic compound such as silicon oxide or alumina is vapor-deposited may be mentioned. The aluminum has a thickness of 20 to 80 μm.

  Moreover, the adhesive strength with the adhesive 15 improves by performing the chemical conversion treatment 7a on the front and back surfaces of the aluminum that is the metal foil layer 7.

  Next, the chemical conversion treatment layer 7a will be described. The chemical conversion treatment layer 7 a is formed on at least the surface of the metal foil layer 7 on the heat-adhesive resin layer 8 side. The chemical conversion treatment layer 7a can stably bond the acid-modified polyolefin layer 9 and the metal foil layer 7 and prevent delamination of the metal foil layer 7 and the heat-adhesive resin layer 8. It also has the function of preventing aluminum corrosion.

  Specifically, delamination between the metal foil layer 7 and the heat-adhesive resin layer 8 at the time of embossing by forming an acid-resistant film such as phosphate, chromate, fluoride, triazine thiol compound, etc. And hydrogen fluoride produced by the reaction between the electrolyte and water in the lithium ion battery prevents the aluminum surface from being dissolved and corroded, especially the aluminum oxide present on the aluminum surface from being dissolved and corroded. Surface adhesion (wetting) can be improved.

  The chemical conversion treatment layer 7a is made of metal by chromium-based chemical conversion treatment such as chromate chromate treatment, phosphoric acid chromate treatment, and coating-type chromate treatment, or non-chromium (coating-type) chemical conversion treatment such as zirconium, titanium, and zinc phosphate. Although it is formed on the surface of the foil layer 7, it is firmly bonded to the fluororesin 15, and a continuous process is possible and a water washing step is unnecessary and the processing cost can be reduced. It is most preferable to treat with a treatment solution containing a coating type chemical conversion treatment, particularly an aminated phenol polymer, a trivalent chromium compound and a phosphorus compound.

  Moreover, as a formation method of the chemical conversion treatment layer 7a, a known coating method such as a barcode method, a roll coating method, a gravure coating method, a dipping method, or the like may be selected to form the processing liquid. Moreover, before forming the chemical conversion treatment layer 7a, the surface of the metal foil layer 7 is previously treated by a known degreasing method such as an alkali dipping method, an electrolytic cleaning method, an acid cleaning method, an acid activation method, or the like. However, it is preferable in that the function of the chemical conversion treatment layer 7a is maximized and can be maintained for a long time.

  In addition, for each of the above layers, corona treatment, blast treatment, and oxidation treatment are appropriately performed for the purpose of improving and stabilizing film forming properties, lamination processing, and final product secondary processing (pouching, embossing). Surface activation treatment such as ozone treatment may be performed.

  The present invention is not limited to the above-described embodiments, and various modifications are possible. Embodiments obtained by appropriately combining technical means disclosed in different embodiments are also included in the present invention. Included in the technical scope.

Next, the insulating property of the packaging material in which the folding direction of the peripheral edge of the packaging material according to the present invention is matched with the MD direction of the heat-adhesive resin layer will be described below with reference to examples.
[Example]

[Production of packaging materials]
First, the manufacturing method of the packaging material for electrochemical cells used in a present Example is demonstrated. First, a chemical conversion treatment was performed on both surfaces of aluminum (thickness 40 μm), and a stretched nylon film (thickness 25 μm) was bonded to one chemical conversion treatment surface by a dry laminating method via a two-component curable polyurethane adhesive. . Next, acid-modified polypropylene (hereinafter abbreviated as acid-modified PP) is applied and baked on the other chemical conversion treated surface by a roll coating method, and an unstretched polypropylene film (thickness 30 μm) is laminated by a thermal laminating method. The packaging material for electrochemical cells used in the examples was obtained. At this time, the thickness of the acid-modified PP is 15 μm.

In this example, the chemical conversion treatment layer was coated with a treatment liquid composed of a phenol resin, a chromium fluoride compound, and phosphoric acid by a roll coating method, and baked under conditions where the film temperature was 190 ° C. or higher. Here, the application amount of chromium is 10 mg / m ² (dry weight), and the acid-modified PP is baked under the condition that the aluminum temperature is 140 ° C. or higher, and the application amount of the acid-modified PP is 3 g / m ² (dry). Weight).

[Production of tab film]
Next, maleic acid-modified polypropylene was extruded on one side of a 12 μm thick polyethylene naphthalate film (PEN film) to a thickness of 44 μm using a T-die extruder, and then maleic acid-modified polypropylene was applied to the other side of the PEN film. A tab film was obtained by extrusion coating to a thickness of 44 μm with a T-die extruder.

[Preparation of sample]
A tray having an embossed portion of 54 mm (TD direction) × 32 mm (MD direction) and a depth of 4 mm is formed on the packaging material for an electrochemical cell, and a 7 mm wide seal region is formed on the periphery of the embossed portion. The tab 1 and the tab 2 having a thickness of 3 mm × 10 mm and a thickness of 100 μm on one side of the tray are placed on the same short side (32 mm width) of the embossed portion in a state where the tab film is wound. It was sandwiched between cell packaging materials, and the periphery was heat-sealed with a width of 7 mm. And it stored at 60 degreeC for 24 hours, and obtained the sample concerning Example 1. At this time, the heat sealing was performed under conditions of a surface pressure of 1.0 MPa, a sealing temperature of 190 ° C., and a sealing time of 3.0 seconds.

  A tray having an embossed portion of 54 mm (MD direction) × 32 mm (TD direction) and a depth of 4 mm and a 7 mm wide sealing region at the periphery of the embossed portion is formed on the packaging material for electrochemical cells, and an electrolyte solution is applied to the embossed portion. The tab 1 and the tab 2 having a thickness of 3 mm × 10 mm and a thickness of 100 μm on one side of the tray are placed on the same short side (32 mm width) of the embossed portion in a state where the tab film is wound. It was sandwiched between cell packaging materials, and the periphery was heat-sealed with a width of 7 mm. And it stored at 60 degreeC for 24 hours, and the sample which concerns on the comparative example 1 was obtained. At this time, the heat sealing was performed under conditions of a surface pressure of 1.0 MPa, a sealing temperature of 190 ° C., and a sealing time of 3.0 seconds.

  A tray having an embossed portion of 100 mm (TD direction) × 55 mm (MD direction) and a depth of 6 mm and a seal region of 15 mm width at the periphery of the embossed portion is formed on the packaging material for electrochemical cells, and an electrolytic solution is applied to the embossed portion. The tab 1 and the tab 2 having a thickness of 30 mm × 50 mm and a thickness of 300 μm on one side of the tray are respectively placed on the short sides (55 mm width) of the embossed portion in a state where the tab film is wound. It was sandwiched between packaging materials for chemical cells, and the periphery was heat-sealed with a width of 15 mm. And it stored at 60 degreeC for 24 hours, and obtained the sample concerning Example 2. At this time, the heat sealing was performed under conditions of a surface pressure of 1.0 MPa, a sealing temperature of 190 ° C., and a sealing time of 3.0 seconds.

  A tray having an embossed portion of 100 mm (MD direction) × 55 mm (TD direction) and a depth of 6 mm and a seal region of 15 mm width at the periphery of the embossed portion is formed on the packaging material for an electrochemical cell, and an electrolytic solution is applied to the embossed portion. The tab 1 and the tab 2 having a thickness of 30 mm × 50 mm and a thickness of 300 μm on one side of the tray are respectively placed on the short sides (55 mm width) of the embossed portion in a state where the tab film is wound. It was sandwiched between packaging materials for chemical cells, and the periphery was heat-sealed with a width of 15 mm. And it stored at 60 degreeC for 24 hours, and the sample which concerns on the comparative example 2 was obtained. At this time, the heat sealing was performed under conditions of a surface pressure of 1.0 MPa, a sealing temperature of 190 ° C., and a sealing time of 3.0 seconds.

[Measurement of insulation at the periphery of packaging materials]

  Next, in each of the above samples, the opposite long sides of the heat-sealed packaging material peripheral portion were bent. At this time, in Examples 1 and 2, the folding direction coincided with the MD direction, and in Comparative Examples 1 and 2, the folding direction coincided with the TD direction. In the bending step, each side was reciprocated 90 ° and bent 20 times.

  Next, the positive electrode terminal was set to the tab and the tip of the negative electrode terminal was set to reach the aluminum foil of the outer package, and a voltage of 25 V was applied for 5 seconds with a voltmeter to measure the resistance value. At this time, the occurrence rates of resistance values of 100 MΩ or less were measured for tab 1 and tab 2 at n = 1000, and are summarized in Table 1.

  As mentioned above, Example 1 and Example 2 which bent the packaging material peripheral part in MD direction should confirm high insulation compared with the comparative example 1 and comparative example 2 which bent the packaging material peripheral part in TD direction. I was able to. From this result, it was confirmed that by matching the folding direction of the peripheral portion of the packaging material with the MD direction of the heat-adhesive resin layer constituting the packaging material, a decrease in insulation due to bending was prevented.

It is sectional drawing which shows the layer structure of the packaging material (laminated body) which concerns on the flat type electrochemical cell of this invention. It is a top view of the laminated body which shows the manufacturing process of the flat type electrochemical cell of this invention. It is a top view of the laminated body which shows the manufacturing process of the flat type electrochemical cell of this invention. It is a top view of the laminated body which shows the manufacturing process of the flat type electrochemical cell of this invention. It is a perspective view of the laminated body which shows the manufacturing process of the flat type electrochemical cell of this invention. It is a top view of the flat type electrochemical cell which shows the manufacturing process of the flat type electrochemical cell of this invention. It is a perspective view of the conventional pouch-type flat electrochemical cell. It is a disassembled perspective view of the conventional pouch-type flat electrochemical cell. It is a perspective view of the conventional embossed flat type electrochemical cell. It is a disassembled perspective view of the conventional emboss type flat type electrochemical cell. It is a perspective view of the conventional embossed flat type electrochemical cell.

Explanation of symbols

1 Lithium ion battery 2 Lithium ion battery body 4 Metal terminal (tab)
6 Base material layer 7 Metal foil 7a Chemical conversion treatment layer 8 Thermal adhesive resin 9 Acid-modified polyolefin 10 Packaging material (laminate)
10a Tray part 10b Sheet part 10c Peripheral part of packaging material 10c Bending part 12 Adhesive layer 15 Plastic case

Claims (3)

A base material layer, a metal foil layer, and a heat-adhesive resin layer are formed in a packaging material formed by overlapping a laminate in which at least a layer is sequentially laminated.
A flat electrochemical cell body including a positive electrode composed of a positive electrode active material and a positive electrode current collector, a negative electrode composed of a negative electrode active material and a negative electrode current collector, and an electrolyte filled between the positive electrode and the negative electrode,
The tip of the tab connected to the negative electrode and the positive electrode protrudes outside the packaging material,
Thermally bonding the peripheral edge of the packaging material, sealing the flat electrochemical cell body inside the packaging material,
A flat electrochemical cell that bends the thermally bonded peripheral edge of the packaging material,
The laminated body is stacked so that the direction in which the fold line formed when the thermally bonded peripheral edge is folded is perpendicular to the flow direction (MD direction) of the resin constituting the thermal adhesive resin layer. A flat electrochemical cell characterized by being combined. 2. The flat electrochemical cell according to claim 1, wherein a drawing direction of the tab and a flow direction (MD direction) of a resin constituting the thermoadhesive resin layer are orthogonal to each other. The laminate has a recess formed by pressing,
A flat electrochemical cell storing the flat electrochemical cell main body in the recess,
The recess is formed in a rectangular parallelepiped shape,
3. The flat electrochemical cell according to claim 1, wherein a longitudinal direction of the concave portion and a flow direction (MD direction) of a resin constituting the thermoadhesive resin layer are orthogonal to each other.

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