JP5423825B2 - Lithium battery exterior - Google Patents

Description

  The present invention relates to a secondary battery, and more particularly to an outer package of a lithium battery having an electrolyte (liquid or solid electrolyte).

  A lithium battery is also called a lithium secondary battery, which is a battery made of a solid polymer, a gel polymer, a liquid, etc. as an electrolyte, and that generates electricity by the movement of lithium ions. It includes what consists of. The structure of the lithium secondary battery is as follows: positive electrode current collector (aluminum) / positive electrode active material layer (polymeric positive electrode material such as metal oxide, carbon black, metal sulfide, electrolyte, polyacrylonitrile) / electrolyte (propylene carbonate, ethylene Carbonate electrolyte such as carbonate, dimethyl carbonate, ethylene methyl carbonate, inorganic solid electrolyte composed of lithium salt, gel electrolyte) / negative electrode active substance layer (lithium metal, alloy, carbon, electrolyte, polymer negative electrode material such as polyacrylonitrile) ) / A battery element made of a negative electrode current collector (copper) and an outer package for packaging the battery element. Lithium secondary batteries are widely used in electronic devices and electronic components, particularly mobile phones, notebook computers, video cameras and the like because of their high volumetric efficiency and weight efficiency.

  As the exterior body of the lithium battery, the metal terminal can be easily taken out, sealed, or flexible so that it has a shape suitable for an appropriate space of an electronic device or an electronic component. Since the shape of the electronic component itself can be designed to some extent, it is easy to reduce the size and weight, etc., so that the exterior body is made of a flexible packaging material in which metal foil such as plastic film or aluminum is laminated. Has come to be used.

  The packaging material has physical properties required for a lithium battery, that is, moisture resistance, sealability, puncture resistance, insulation, heat / cold resistance, electrolyte resistance (electrolytic solution resistance), corrosion resistance ( The resistance to hydrofluoric acid generated by electrolyte deterioration and hydrolysis is required as an essential component, so that the packaging material is a piercing resistance and a base material layer for preventing external energization, moisture-proof In general, a laminate composed of a barrier layer made of a metal foil such as aluminum for securing the property, and an inner layer for securing the sealing property as well as excellent adhesion to the metal terminal is used.

  As a form of a lithium battery using a packaging material as an exterior body, the packaging material is processed into a cylindrical shape, and a battery terminal and a metal terminal connected to each of the positive electrode and the negative electrode are stored in a state protruding outward, A bag type (for example, see Patent Document 1) and a packaging material, which are sealed by thermally bonding the parts, are formed into a container shape, and metal terminals connected to the battery element and each of the positive electrode and the negative electrode are placed outside in the container. There is known a molding type (see, for example, Patent Document 2) which is housed in a protruding state, covered with a flat packaging material or a container-shaped packaging material, and sealed by thermally bonding four peripheral edges.

  In any of the above-described lithium batteries, when the battery element is sealed with the packaging material, the battery terminal and the metal terminal connected to each of the positive electrode and the negative electrode are projected to the outside, and the metal terminal is It is necessary to seal by thermal bonding in a sandwiched state. For this purpose, the inner layer of the packaging material is heat-adhered and sealed with a heat-adhesive resin having good adhesion to the metal, for example, an acid-modified olefin resin graft-modified with an unsaturated carboxylic acid, or The above-mentioned acid modification that uses a general olefin resin (linear or branched olefin resin composed of carbon and hydrogen) that has poor adhesion to metal for the inner layer and has good adhesion to the metal A method is generally employed in which an adhesive film for sealing a metal terminal portion made of an olefin resin is interposed between the metal terminal and the inner layer to be thermally bonded and sealed.

  And compared with the secondary battery which consists of a bag type described in patent document 1, the molded type secondary battery described in patent document 2 can store a battery element etc. tightly (tight state). Therefore, there is an advantage that the volume energy density can be improved, and there is an advantage that the battery element or the like can be easily stored, and the molding type is mainly used.

  In recent years, environmental pollution due to exhaust gas has become a problem, and electric cars using electricity as a power source and hybrid cars that run in combination with an engine and a motor are attracting attention. Since such a hybrid car uses electric power supplied from the battery at the time of start or full acceleration, a high output is required for the battery. In addition, a hybrid car must be equipped with many components such as an engine, a motor / generator, and a battery, which increases the weight of the entire vehicle. Lithium batteries are attracting attention as alternatives to lead, nickel cadmium, nickel metal hydride batteries, etc., as well as demand for output and light weight.

  By the way, unlike batteries used in mobile products such as mobile phones, laptop computers, video cameras, etc., a high voltage is required to drive a motor, and usually a plurality of batteries are installed in such a hybrid car. The unit cells are connected in series. For example, in order to obtain a battery voltage of 300V, about 150 unit cells are connected in series for a lead battery of 2V per unit cell, and about 80 unit cells are connected in series for a lithium battery of 3.6V per unit cell. Will do.

  In such a battery module in which a large number of single cells are connected in series, in a battery having a low volumetric energy density such as a lead battery, a nickel cadmium, or a nickel metal hydride battery, instead of individual outputs being low, overdischarge or Even if it is overcharged, there is little deterioration in performance and it is unlikely that it will become unusable. However, lithium batteries are repeatedly charged and discharged, or the internal pressure is generated by gas generated from the electrolyte (electrolyte) in a high-temperature environment. In particular, in an exterior body made of a flexible packaging material, there is a possibility that the exterior body expands and bursts, and there is a problem that battery life characteristics such as battery deterioration and output decrease are lowered.

  Therefore, the proposal which prevents the expansion | swelling of the exterior body which consists of a flexible packaging material is made | formed (for example, refer patent document 3). In the thin battery described in Patent Document 3, by providing a portion having a low adhesive strength in a part of the thermal bonding portion that seals the battery element of the lithium battery, the increased internal pressure is released from this portion and the battery performance is deteriorated. It is intended to improve the reliability at the time of abnormality while preventing the above.

  However, the battery module formed by connecting a large number of thin batteries (unit cells) described in Patent Document 3 in series has the following problems. That is, when the elevated internal pressure is released from a weakly bonded portion provided in a part of the thermal bonding portion, the electrolytic solution also leaks from this portion, thereby forming a metal foil such as aluminum used for flexible packaging materials. If the barrier layers are electrically connected to each other between the cells, and if for some reason a pinhole occurs in the inner layer of the cells and the electrolyte contacts the barrier layer, the barrier layer will have a high potential. As a result, there is a problem that the barrier layer dissolves and does not function as a battery. In this specification, “battery” or “single cell” means a battery sealed with a flexible packaging material in a state in which one battery element and a metal terminal connected to each of the positive electrode and the negative electrode are projected. The “battery module” refers to a battery in which a plurality of the above-described batteries or single cells are electrically connected.

JP-A-9-213285 JP 2001-229888 A Japanese Patent Laid-Open No. 10-55792

Therefore, the present invention prevents the deterioration of the battery performance by letting the gas generated inside the battery escape to the outside from the part with weak adhesive strength provided in a part of the thermal bonding part, and electrolysis from the part where the gas escapes to the outside. It is to provide an outer package of a lithium battery capable of preventing liquid from leaking outside the battery, and in particular, a barrier made of a metal foil such as aluminum used for a flexible packaging material between batteries in a battery module. An object of the present invention is to provide a highly reliable lithium battery exterior body that can reduce the risk of electrical connection between layers by an electrolyte.

A battery element comprising a rectangular molded container body having flange portions at four peripheral edges and a lid body having a size substantially the same as the rectangular molded container body, and having a positive electrode and a negative electrode in a recess of the rectangular molded container body A lithium battery in which a metal terminal connected to each of the positive electrode and the negative electrode protrudes outward from the flange portion, is covered with the lid, and the four peripheral edges of the flange portion are sealed with an annular peripheral heat bonding portion In the exterior body, the peripheral thermal bonding has a first unbonded region between an inner edge and an outer edge of the peripheral thermal bonding portion, and divides the first unbonded region and the concave portion of the rectangular molded container body. Gas releasing means for peeling off earlier than any part of the annular peripheral heat-bonding portion that surrounds the recess from the interface that is formed by heat sealing and heat-sealed due to an increase in internal pressure Both the second unbonded areas as communication ports for communicating the first non-bonded region and outside the peripheral heat-bonding portion partitioning the outside of the first non-adhesive region is provided, wherein the first non-bonded An exterior body of a lithium battery, wherein the rectangular molded container body corresponding to the region has a molded recess formed on the same side as the recess for storing a battery element.

According to a second aspect of the present invention, in the outer package of the lithium battery according to the first aspect, the flange portion that provides the first unbonded region is formed wide.

According to a third aspect of the present invention, in the outer package of the lithium battery according to any one of the first and second aspects, the metal terminal does not protrude from the flange portion that provides the first unbonded region. It is characterized by this.

According to a fourth aspect of the present invention, in the lithium battery exterior body according to any one of the first to third aspects, the lid is a rectangular molded container having substantially the same shape as the rectangular molded container body. It is characterized by this.

Further, the present invention according to claim 5 is the lithium battery exterior body according to any one of claims 1 to 4, wherein the lid body is connected via one end side of the rectangular molded container body. It is characterized by being.

The present invention according to claim 6 is the exterior body of the lithium battery according to any one of claims 1 to 5, wherein the lid body and the rectangular molded container body are at least a base material layer, an aluminum foil, It consists of a packaging material in which a chemical conversion treatment layer, an adhesive layer, and a thermoadhesive resin layer are laminated in order.

Exterior body of the lithium battery of the present invention, the gas released into the peripheral heat-bonding portion for partitioning the concave portion of the first non-adhesive region and the rectangular shaped container body thereby forming a first non-adhesive region to the peripheral heat-bonding portion It means provided, and by providing the second non-adhesive region as a communication port for communicating the first non-bonded region and outside the peripheral heat-bonding portion for partitioning the first non-bonded region and an exterior , relief elevated pressure with gas generated in the battery from the gas discharge means to the first unbonded regions can further escape to the outside by the second unbonded areas as communication port from said first non-bonded region, There exists an effect that the fall of battery performance can be prevented. In addition, since the first unbonded region is provided, the electrolyte solution that leaks together with the gas can be stored in the first unbonded region, so that the electrolyte solution can be prevented from leaking outside the battery. In the module battery, the metal foil such as aluminum used in the flexible packaging material of the battery has an excellent effect that it is not electrically connected between the batteries by the electrolytic solution.

BRIEF DESCRIPTION OF THE DRAWINGS (a) which shows typically 1st Embodiment of the exterior body of the lithium battery concerning this invention is a top view, (b) is XX sectional drawing of (a). It is a figure corresponding to Drawing 1 (b) showing a 2nd embodiment of an exterior body of a lithium battery concerning the present invention. It is a figure corresponding to FIG.1 (b) which shows 3rd Embodiment of the exterior body of the lithium battery concerning this invention schematically. It is a figure which shows typically one Example of the laminated constitution of the flexible packaging material used for the exterior body of the lithium battery concerning this invention. It is a principal part top view which shows schematically one Example of the gas discharge | release means provided in the exterior body of the lithium battery concerning this invention. It is a principal part perspective view which shows schematically one Example of the 2nd non-bonding area | region as a communicating port provided in the exterior body of the lithium battery concerning this invention.

The present invention will be described in detail below with reference to the drawings.
Figure 1 is a first embodiment of the exterior body of the lithium battery according to the present invention schematically shown (a) is a plan view, (b) is sectional view taken along line X-X of (a), in Figure 2 the present invention FIG. 3 is a diagram corresponding to FIG. 1B schematically showing a second embodiment of the outer package of the lithium battery, and FIG. 3 is a diagram schematically showing the third embodiment of the outer package of the lithium battery according to the present invention. corresponding to (b) FIG. 4 shows schematically shown FIG an example of the layer structure of flexible packaging material used in exterior body of the lithium battery according to the present invention, FIG 5 is a lithium battery according to the present invention FIG. 6 is a plan view of an essential part schematically illustrating an embodiment of a gas releasing means provided in the exterior body, and FIG. 6 illustrates an embodiment of the second unbonded region as a communication port provided in the exterior body of the lithium battery according to the present invention. FIG. 1 is a perspective view of a main part, in which 1, 1 ′, 1 ″ denotes a lithium battery exterior body, and 2 denotes a rectangular shape. Shaped container body, 3 and 3 ′ are lids, 4 is a gas releasing means, 5 is a second unbonded region as a communication port, 5 ′ is a tube, 10 is a base material layer, 20 and 50 are adhesive layers, 30 Is a chemical conversion treatment layer, 40 is an aluminum foil, 60 is a heat-adhesive resin layer, F is a flange portion, H is a packaging material, M is a first unbonded region, S, S1 and S2 are peripheral heat-bonded portions, and T is a metal A terminal, U1 indicates a recess, and U2 indicates a recess.

1 schematically shows a first embodiment of the exterior body of the lithium battery according to the present invention (a) is a plan view, (b) is a sectional view taken along line X-X of (a), the lithium battery The exterior body 1 includes a rectangular molded container body 2 having flange portions F on the four peripheral edges, and a lid body 3 having the same size as the rectangular molded container body 2, and a concave portion U1 of the rectangular molded container body 2. A battery element (not shown) having a positive electrode and a negative electrode is accommodated therein, and a metal terminal T connected to each of the positive electrode and the negative electrode is projected outward from the flange portion F and covered with the lid 3. The flange portion F is sealed by a peripheral heat bonding portion S, and has a first unbonded region M in the peripheral heat bonding portion S of the flange portion F formed wide . The unbonded region M and the concave portion U1 of the rectangular molded container body 3 are partitioned. Has a gas release means 4 to the peripheral heat-bonding portion S1, the first non-bonded region M and the communicating port communicating with said first non-bonded region M and outside the peripheral heat-bonding portion S2 partitioning the external The second unbonded region 5 is provided. The lithium battery made of the outer package 1 is suitable for being a battery module with the metal terminal T upright, and the second unbonded region 5 as a communication port is provided on the metal terminal T side. The gas discharge means 4 is provided below the position of the second unbonded region 5 as the communication port.

The exterior body 1 of the lithium battery configured as described above is a place where the gas release means described later functions and the gas release means is provided when gas is generated inside the battery due to abnormality such as overcharge and the internal pressure rises. There was peeled off, when the peeling reaches the first non-adhesive region M gas is led to the first non-adhesive region M, the gas introduced into the first unbonded area M and the second non-adhesive region 5 as communicating port Even if the electrolyte is leaked from the location where the gas releasing means functions and the gas is released, the electrolyte does not leak to the outside because it accumulates in the first unbonded region. High battery.

FIG. 2 is a view corresponding to FIG. 1B schematically showing a second embodiment of the exterior body of the lithium battery according to the present invention, and the exterior body 1 ′ of the lithium battery is the first embodiment shown in FIG. In the outer casing 1 of the lithium battery according to the embodiment, a concave portion U2 is formed in the rectangular molded container body 2 corresponding to the first unbonded region M, and the rest is shown in FIG. The same as in the first embodiment. The lithium battery made of the exterior body 1 'is suitable for being a battery module with the concave portion U1 side down, and the position where the second unbonded region 5 and the gas releasing means 4 are provided as communication ports . Although not particularly limited, by providing the second unbonded region 5 and the gas discharge means 4 as a communication port in a position shifted in the horizontal direction so as not to be in a straight line, there is a possibility that the gas will come out at the same time as the gas is released. It is possible to prevent a certain electrolyte from splashing outside from the second unbonded region as the communication port.

The lithium battery exterior body 1 ′ configured as described above has a location where the gas releasing means functions and the gas releasing means is provided when gas is generated inside the battery due to an abnormality such as overcharge and the internal pressure rises. peeled, gas when the peeling reaches the first unbonded areas M (recessed portion U2) is introduced into the first non-adhesive region M (recessed portion U2), the first electrically in unbonded areas M (recessed portion U2) The discharged gas is discharged to the outside from the second non-bonded region 5 as a communication port , and even if the electrolyte leaks from the part peeled off by the function of the gas discharge means, the electrolyte is not discharged into the first unbonded region M (dent Since it accumulates in the portion U2), it does not leak to the outside, and a highly reliable battery can be obtained. In addition, 2nd Embodiment shown in FIG. 2 is good also as a battery module in the state which stood the metal terminal T side upwards like 1st Embodiment shown in FIG.

FIG. 3 is a view corresponding to FIG. 1B schematically showing a third embodiment of the exterior body of the lithium battery according to the present invention, and the exterior body 1 ″ of the lithium battery is the first embodiment shown in FIG. In the exterior body 1 of the lithium battery according to the embodiment, the rectangular molded container body 2 is used as the lid body 3 ′ instead of the lid body 3, and other than this, the first embodiment shown in FIG. Since the battery exterior body 1 "configured in this way can have a recess for housing a battery element (not shown) larger than the recess U1 of the first embodiment, it has a high capacity and a high output. It is preferable as a battery outer package. Moreover, although not shown in figure, the recessed part U2 shown in FIG. 2 in the 1st un-bonded area | region M may be provided in any one side, and may be provided in any side.

Next, the flexible packaging material used for the exterior body 1, 1 ′, 1 ″ of the lithium battery will be described. FIG. 4 shows an example of the layer structure of the flexible packaging material used for the exterior body of the lithium battery according to the present invention. The packaging material H includes a base material layer 10, an adhesive layer 20, a chemical conversion treatment layer 30, an aluminum foil 40, a chemical conversion treatment layer 30, an adhesive layer 50, and thermal adhesiveness. The resin layer 60 is laminated in order.

  The base layer 10 is provided for the purpose of protecting the aluminum foil from external force and improving the puncture resistance against puncture from the outside. Polyester stretched in the biaxial direction from the viewpoint of excellent mechanical strength. Examples thereof include a film, a polyamide film, and a laminate thereof. Examples of the polyester film include films made of polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polycarbonate, and the like, and examples of the polyamide film include nylon 6, nylon 6,6, nylon 6, A film composed of 10 etc. can be mentioned. The thickness of the base material layer is suitably 6 μm or more. The reason for this is that if the thickness is less than 6 μm, there may be pinholes in itself, and the protective effect of the aluminum foil against external force will be reduced. This is because breakage is likely to occur and molding defects are likely to occur, and more preferably 12 μm or more. In addition, if the substrate layer is thicker than 25 μm, whether it is a single layer or multiple layers of the above-mentioned film, no significant effect is observed in terms of protecting the aluminum foil against external force, and the volume and weight energy density are reduced. In addition, it is desirable not to use it from the viewpoint of cost effectiveness. In addition, the above-described polyester film and polyamide film may be subjected to easy adhesion treatment such as corona discharge treatment, ozone treatment, and plasma treatment on a necessary surface.

  The aluminum foil 40 is provided to prevent water vapor from entering the inside of the battery from the outside. The aluminum foil 40 has a thickness of 20 to 200 μm in consideration of ensuring the water vapor barrier property and processing suitability during processing. Is appropriate. If the thickness is less than 20 μm, the pinhole of the aluminum foil alone is concerned, and the risk of intrusion of water vapor increases, and if the thickness exceeds 200 μm, a remarkable effect is recognized on the pinhole of the aluminum foil. In addition, it is desirable that further improvement of the water vapor barrier property cannot be expected, the processability is inferior, the volume and the weight energy density are lowered, and the cost effectiveness is not used.

  In addition, the aluminum foil 40 contains 0.3 to 9.0% by weight, preferably 0.7 to 2.0% by weight of iron, and has excellent ductility as compared with the one not containing iron, and is resistant to bending. It is preferable to use an aluminum foil containing iron in order to obtain a uniform molded product with little occurrence of pinholes and no uneven thickness especially during press molding. If the iron content is less than 0.3% by weight, no effect is observed in prevention of pinholes and spreadability, and if the iron content exceeds 9.0% by weight, the flexibility as an aluminum foil is hindered. However, the moldability decreases.

  Although the aluminum foil 40 is manufactured by cold rolling, its flexibility, waist strength and hardness change under annealing (so-called annealing treatment) conditions, but the aluminum foil used in the present invention is annealed. An aluminum foil that tends to be softer than the hard-treated product that has been annealed to some degree or completely is preferable. The aluminum foil 40 used in the present invention is preferably 8000 to 3000 series.

  Next, the chemical conversion treatment layer 30 will be described. The chemical conversion treatment layer 30 prevents the aluminum foil 40 from being corroded by an electrolytic solution or hydrofluoric acid generated by hydrolysis of the electrolytic solution, and firmly bonds the aluminum foil 40 and the adhesive layers 10 and 50 described later. It is provided to prevent delamination due to hydrofluoric acid generated by hydrolysis of the electrolytic solution or electrolytic solution and to prevent delamination during press molding.

  The chemical conversion treatment layer 30 is formed 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 formed on the surface of the aluminum foil 40, a coating type chemical conversion treatment is suitable because continuous treatment is possible and a water washing step is unnecessary and the treatment cost can be reduced. The treatment solution may be treated with a conventionally known chromate treatment solution containing a hexavalent chromium compound, but is environmentally friendly and does not easily cause a decrease in the adhesive strength between the layers as time passes. Specifically, it is preferably formed using a treatment liquid containing an aminated phenol polymer, a trivalent chromium compound, and a phosphorus compound.

First, the aminated phenol polymer will be described. A well-known thing can be widely used as an aminated phenol polymer, for example, aminated phenol heavy which consists of a repeating unit represented by following formula (1), (2), (3), (4). Coalescence can be mentioned. X in the formula represents a hydrogen atom, a hydroxyl group, an alkyl group, a hydroxyalkyl group, an allyl group or a benzyl group. R ₁ and R ₂ represent a hydroxyl group, an alkyl group, or a hydroxyalkyl group, and may be the same group or different groups.

In the following formulas (1) to (4), examples of the alkyl group represented by X, R ₁ and R ₂ include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, C1-C4 linear or branched alkyl groups, such as a tert- butyl group, can be mentioned. Examples of the hydroxyalkyl group represented by X, R ₁ and R ₂ include a hydroxymethyl group, a 1-hydroxyethyl group, a 2-hydroxyethyl group, a 1-hydroxypropyl group, a 2-hydroxypropyl group, 3- C1-C4 straight or branched chain in which one hydroxy group such as hydroxypropyl group, 1-hydroxybutyl group, 2-hydroxybutyl group, 3-hydroxybutyl group, 4-hydroxybutyl group is substituted An alkyl group can be mentioned. X in the following formulas (1) to (4) is preferably any one of a hydrogen atom, a hydroxyl group, and a hydroxyalkyl group.

Further, the aminated phenol polymer represented by the following formulas (1) and (3) is an aminated phenol containing about 80 mol% or less of repeating units, preferably about 25 to about 55 mol% of repeating units. It is a polymer. The number average molecular weight of the aminated phenol polymer is preferably about 500 to about 1 million, more preferably about 1000 to about 20,000. The aminated phenol polymer is produced, for example, by polycondensing a phenol compound or naphthol compound and formaldehyde to produce a polymer comprising repeating units represented by the following (1) to (3). It is produced by introducing a water-soluble functional group (—CH ₂ NR ₁ R ₂ ) using formaldehyde and an amine (R ₁ R ₂ NH). The aminated phenol polymer can be used singly or in combination of two or more.

  Next, the trivalent chromium compound will be described. As the trivalent chromium compound, known compounds can be widely used. For example, chromium nitrate, chromium fluoride, chromium sulfate, chromium acetate, chromium oxalate, chromium biphosphate, chromic acetyl acetate, chromium chloride, sulfuric acid Potassium chromium etc. can be mentioned, Preferably they are chromium nitrate and chromium fluoride.

  Next, a phosphorus compound is demonstrated. As a phosphorus compound, a well-known thing can be used widely, For example, condensed phosphoric acids, such as phosphoric acid and polyphosphoric acid, these salts, etc. can be mentioned. Here, as said salt, alkali metal salts, such as ammonium salt, sodium salt, potassium salt, can be mentioned, for example.

And as said chemical conversion treatment layer formed using the processing liquid containing an aminated phenol polymer, a trivalent chromium compound, and a phosphorus compound, about 1 to about 200 mg of an aminated phenol polymer per 1 m ² , It is appropriate that the trivalent chromium compound is contained in a proportion of about 0.5 to about 50 mg in terms of chromium, and the phosphorus compound is contained in a proportion of about 0.5 to about 50 mg in terms of phosphorus. More preferably, about 5.0 to 150 mg, the trivalent chromium compound is contained in a proportion of about 1.0 to about 40 mg in terms of chromium, and the phosphorus compound is contained in a proportion of about 1.0 to about 40 mg in terms of phosphorus. In this case, the drying temperature is 150 to 250 ° C., preferably 170 to 250 ° C., and the heat treatment (baking treatment) is appropriate.

  Moreover, as a formation method of the said chemical conversion treatment layer, the said process liquid should just be formed by selecting suitably the well-known coating methods, such as a bar-coat method, a roll-coating method, a gravure coating method, and an immersion method. Further, before forming the chemical conversion treatment layer, the surface of the aluminum foil is previously subjected to a known degreasing treatment method such as an alkali dipping method, an electrolytic cleaning method, an acid cleaning method, an electrolytic acid cleaning method, or an acid activation method. It is preferable to perform the treatment from the viewpoint that the function of the chemical conversion treatment layer can be maximized and can be maintained for a long period of time.

  Next, the adhesive layers 20 and 50 will be described. First, the adhesive layer 50 is provided to firmly bond the chemical conversion treatment layer 30 of the aluminum foil 40 and the thermal adhesive resin layer 60 described later, and the adhesive layer 50 is formed. If one of them is exemplified as the resin, for example, a polyolefin resin graft-modified with an unsaturated carboxylic acid, an acid-modified polyolefin resin such as a copolymer of ethylene or propylene and acrylic acid, or methacrylic acid, particularly preferably A polyolefin resin graft-modified with an unsaturated carboxylic acid can be mentioned. As a method for forming the adhesive layer 50, the resin described above is melt-extruded on the surface of the chemical conversion layer 30 of the aluminum foil 40 using a T-die extruder. Then, a so-called sand for laminating a resin film constituting the thermal adhesive resin layer 60 described later You may form by laminating | stacking by the lamination method, and you may laminate | stack on the said chemical conversion treatment layer 30 surface of the said aluminum foil 40 by the thermal lamination method using the film which made the resin mentioned above into a sheet. Is. In this case, the thickness of the adhesive layer 50 is 5 to 20 μm, preferably 10 to 15 μm. If the thickness is less than 5 μm, sufficient laminate strength cannot be obtained, and if it exceeds 20 μm, moisture permeation from the end face increases. This is because the battery performance may be reduced.

If another example of the resin forming the adhesive layer 50 is exemplified, for example, a well-known two-component curable dry lamination adhesive composed of a main component such as polyester, polyether or polyurethane may be mentioned. be able to. As the method for forming the adhesive layer 50, a composition in which an isocyanate compound is blended with the above-mentioned main agent is applied and dried by a known application method such as a gravure coating method or a roll coating method, and the thermal adhesive resin layer 60 is formed. It can form by laminating | stacking by the what is called dry lamination method which laminates | stacks the resin film to comprise. 2.0~5.0g / m ² as a coating amount after drying of the adhesive layer 50, and preferably from to coated to a 3.0 g / m ² or more.

Examples of the adhesive layer 20 include the well-known two-component curable dry lamination adhesive composed of a main component such as polyester, polyether, and polyurethane as described in the adhesive layer 50. as the coating amount, 3.0~5.0g / m ² are suitable.

  Next, the resin that forms the thermal adhesive resin layer 60 will be described. As the resin for forming the heat-adhesive resin layer 60, when a battery element of a lithium battery and a metal terminal connected to each of the positive electrode and the negative electrode are sandwiched in a state of protruding outwardly and thermally bonded and sealed. The resin type differs depending on whether or not a metal terminal portion sealing adhesive film is interposed between the thermal adhesive resin layer 60 and the metal terminal. Since acid-modified olefin resin is usually used as the metal terminal sealing adhesive film, low density polyethylene, medium density polyethylene, high density polyethylene, wire are used when the metal terminal sealing adhesive film is interposed. General olefins such as simple resins or mixtures of propylene resins such as homopolypropylene, ethylene-propylene copolymer, and ethylene-propylene-butene copolymer Resin (linear or branched olefin resin composed of carbon and hydrogen) may be selected as appropriate, and these general olefin resins may be formed into a film and sandwich lamination method. , Dry lamination, thermal lamination, etc. In addition, the heat-adhesive resin layer 60 is exemplified as one of the resins forming the adhesive layer 50, and the acid-modified polyolefin resin and the above-described low density polyethylene, medium density polyethylene, high density polyethylene, linear low A single or mixture of propylene resins such as density polyethylene, ethylene-butene copolymer and other ethylene resins, homopolypropylene, ethylene-propylene copolymer, ethylene-propylene-butene copolymer, etc. The adhesive layer 50 and the thermoadhesive resin layer 60 may be formed at the same time by co-extrusion with the chemical conversion treatment layer 30, or an acid-modified polyolefin type exemplified as one of the resins for forming the adhesive layer 50 in advance. Resin and low density polyethylene, medium density polyethylene, high density polyethylene, linear low density polyethylene Co-extruded films by co-extrusion of propylene resins such as ethylene, ethylene-butene copolymer, homopolypropylene, ethylene-propylene copolymer, ethylene-propylene-butene copolymer May be formed and laminated on the chemical conversion treatment layer 30 of the aluminum foil 40 by a thermal lamination method.

  Further, when no adhesive film for sealing the metal terminal portion is interposed, an acid-modified polyolefin resin exemplified as one of the resins forming the adhesive layer 50, for example, a polyolefin resin graft-modified with an unsaturated carboxylic acid In addition, an acid-modified polyolefin resin such as a copolymer of ethylene or propylene and acrylic acid or methacrylic acid, particularly preferably a polyolefin resin graft-modified with an unsaturated carboxylic acid can be used. It may also serve as. The thickness of the heat-adhesive resin layer 60 is 10 to 100 μm, preferably 30 to 50 μm. If the thickness is less than 10 μm, sufficient adhesive strength cannot be obtained when heat-bonding, resulting in a problem in sealing performance. If the thickness exceeds 100 μm, there is no significant effect on the sealing performance when heat-adhering and sealing, and the total thickness increases to reduce the volume and weight energy density and cost-effectiveness. It is preferable not to use from the viewpoint. In the case where the heat-adhesive resin layer 60 is composed of a film, a necessary surface may be subjected to easy adhesion treatment such as corona discharge treatment, ozone treatment, or plasma treatment.

  Next, the gas release means will be described. Various methods can be adopted as the gas releasing means 4. Specifically, for example, (1) a place where the gas releasing means 4 is provided is more heat-sealed (heating temperature, A method of setting the heat seal strength to be weak by setting the heating time and / or the applied pressure low, or any two conditions, or (2), and (2) the location where the gas release means 4 is provided as described above. A method of heat-sealing the resin constituting the heat-adhesive resin layer 60 and a sheet that adheres easily, for example, when the heat-adhesive resin layer 60 is made of low-density polyethylene, When heat-sealing is performed with an ethylene-rich polypropylene sheet sandwiched, or when the heat-adhesive resin layer 60 is made of polypropylene, propylene is used. By Nari heat sealing across the Nritchi polypropylene sheet, it can be set weak heat seal strength than the peripheral heat seal portion S1 a portion of the gas discharge means 4.

  However, the method (1) has a problem that the heat sealing process is increased by one process, and there is a problem that the stability of the heat sealing strength at the location of the gas releasing means 4 is uneasy. The method involves difficulties in actual work, and there is a problem that the stability of the heat seal strength at the location of the gas releasing means 4 is uneasy.

Therefore, the gas releasing means that has the same strength as the peripheral heat bonding portion S1 and the heat sealing strength at other places where the gas releasing means 4 is provided without changing the number of steps and has excellent stability will be described. FIG. 5 is a plan view of an essential part schematically showing an embodiment of the gas releasing means provided on the outer casing of the lithium battery according to the present invention. FIG. 5 is a diagram corresponding to FIG. A part of the bonding portion S1 is formed of a V-shaped protruding heat bonding portion that protrudes in a V shape from the peripheral heat bonding portion S1 to the concave portion U1 side of the battery exterior body 1, that is, a so-called lip shape. The main point of this V-shaped thermal bonding portion is that the protruding angle of the V-shaped protruding thermal bonding portion is 90 degrees or less, and the protruding end portion on the first unbonded region M side of the V-shaped protruding thermal bonding portion is It is comprised so that it may be located in the said recessed part U1 side rather than the line | wire which tied the edge by the side of the said recessed part U1 of peripheral heat bonding part S1. As the gas releasing means 4, a heat seal bar processed into the above-mentioned shape may be used, and the peripheral thermal bonding portion S (S1 and S2) can be formed by one thermal bonding and the peripheral thermal bonding portion S can be formed. The heat seal strength of (S1 and S2) and the gas releasing means 4 composed of the V-shaped protruding thermal bonding portion can be the same strength.

The gas releasing means 4 composed of the V-shaped protruding heat-bonded portion configured in this way is more effective than the peripheral heat-bonded portion S1 with the increased internal pressure when gas is generated inside the battery due to abnormalities such as overcharge and the internal pressure increases. peeling from the interface was slowly thermal bonding of heat-adhesive resin layer 60 from the earlier of the V-shaped projecting heat-bonding tip also the this peeling reaches the first non-adhesive region M gas into the first non-adhesive region M It can escape and can escape from the 2nd non-adhesion area | region as a communicating port to the exterior.

Next, the second unbonded region 5 as a communication port will be described. The second unbonded region 5 as the communication port may be a mere unbonded portion provided in the peripheral thermal bonding portion S2, but for example, as shown in FIG. The second unbonded region 5 as a communication port, which is appropriately selected according to the resin type of the heat-adhesive resin layer 60 used for the packaging material H forming “, 1”, and into which a polyethylene or polypropylene tube 5 ′ is inserted. As an insertion method of the tube 5 ′, for example, the tube 5 ′ in which a metal rod such as aluminum whose surface is coated with Teflon (registered trademark) resin is inserted in advance is used as a communication port . 2 It may be provided at the same time when the peripheral heat-bonding portion S (S1 and S2) is formed by setting it at a position to be the unbonded region 5, and the second unbonded region 5 as a communication port is unbonded. Shape in advance After that, the tube 5 ′ into which a metal rod such as aluminum whose surface is coated with Teflon (registered trademark) resin is inserted in advance may be inserted and heat sealed with a heat seal bar. By configuring as described above, the tube 5 ′ can be a second unbonded region as the communication port 5 that is reliably opened, and the tube 5 ′ has, for example, a polyethylene or polypropylene layer as an exposed layer and an inner layer. For example, a multi-layer co-extruded tube having a higher melting point than these exposed layers, specifically a polyamide layer, may be used. In this case, the surface is coated with Teflon (registered trademark) resin. without using a metal rod such as aluminum, it is possible to heat seal, the as communication port to ensure complete opening without removing the metal rod The thickness of the unbonded regions can be 5. The tube 5 ', it is generally 0.5~3.0mm is suitable.

1, 1 ′, 1 ″ battery exterior body 2 rectangular shaped container body 3, 3 ′ lid body 4 gas releasing means 5 second unbonded region 5 ′ as a communication port tube 10 substrate layer 20, 50 adhesive layer 30 Chemical conversion treatment layer 40 Aluminum foil 60 Thermal adhesive resin layer F Flange part H Packaging material M First unbonded area S, S1, S2 Peripheral thermal adhesive part T Metal terminal U1 Concave part U2 Concave part

Claims (6)

A battery element comprising a rectangular molded container body having flange portions at four peripheral edges and a lid body having a size substantially the same as the rectangular molded container body, and having a positive electrode and a negative electrode in a recess of the rectangular molded container body A lithium battery in which a metal terminal connected to each of the positive electrode and the negative electrode protrudes outward from the flange portion, is covered with the lid, and the four peripheral edges of the flange portion are sealed with an annular peripheral heat bonding portion In the exterior body, the peripheral thermal bonding has a first unbonded region between an inner edge and an outer edge of the peripheral thermal bonding portion, and divides the first unbonded region and the concave portion of the rectangular molded container body. Gas releasing means for peeling off earlier than any part of the annular peripheral heat-bonding portion that surrounds the recess from the interface that is formed by heat sealing and heat-sealed due to an increase in internal pressure Both the second unbonded areas as communication ports for communicating the first non-bonded region and outside the peripheral heat-bonding portion partitioning the outside of the first non-adhesive region is provided, wherein the first non-bonded An exterior body of a lithium battery, wherein the rectangular molded container body corresponding to the region has a molded recess formed on the same side as the recess for storing a battery element. The outer casing of a lithium battery according to claim 1, wherein the flange portion that provides the first unbonded region is formed wide. The outer casing of a lithium battery according to any one of claims 1 and 2, wherein the metal terminal is not projected from the flange portion that provides the first unbonded region. The outer cover of a lithium battery according to any one of claims 1 to 3, wherein the lid is a rectangular molded container having substantially the same shape as the rectangular molded container main body. 5. The lithium battery exterior body according to claim 1, wherein the lid body is connected via one end of the rectangular molded container body. The lid body and the rectangular molded container body are made of a packaging material in which at least a base material layer, an aluminum foil, a chemical conversion treatment layer, an adhesive layer, and a heat-adhesive resin layer are laminated in order. The exterior body of the lithium battery in any one of Claims 1-5.

Images