JP4730038B2 - Lithium ion battery tab, manufacturing method thereof, and lithium ion battery using the same - Google Patents

Description

  The present invention relates to a tab material for a lithium ion battery showing a stable sealing property with a packaging material, a manufacturing method thereof, and a lithium ion battery using the same.

The lithium ion battery is also referred to as a lithium secondary battery, and includes a battery having a liquid, gel-like, and polymer-like electrolyte, and a positive electrode / negative electrode active material made of a 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. Therefore, in recent years, it has been widely used as a power source for portable devices such as mobile phones, notebook computers, digital cameras, and small video cameras.

  The composition of the lithium ion battery is as follows: positive electrode current collector (aluminum, nickel) / positive electrode active material layer (polymeric positive electrode material such as metal oxide, carbon black, metal sulfide, electrolyte, polyacrylonitrile) / electrolyte layer (propylene carbonate) , Carbonate electrolytes such as ethylene carbonate, dimethyl carbonate, ethylene methyl carbonate, inorganic solid electrolytes composed of lithium salts, gel electrolytes, etc.) / Anode active material layers (lithium metals, alloys, carbon, electrolytes, polyacrylonitrile, etc.) Molecular negative electrode material) / negative electrode current collector (copper, nickel, stainless steel) and an outer package for packaging them. As an exterior body, conventionally, a metal can obtained by pressing a metal into a cylindrical shape or a rectangular parallelepiped shape, or a bag made of a multilayer film composed of an outermost aluminum sealant layer has been used. .

  However, there have been the following problems as the exterior body of the conventional lithium ion battery. In a metal can, since the outer wall of the container is rigid, the shape of the battery itself is determined. Therefore, since the hardware side is designed in accordance with the battery, the size of the hardware using the battery is determined by the battery, and the degree of freedom in shape is lost. On the other hand, a pouch type housing the lithium ion battery main body in a bag shape, or an embossed exterior body by pressing the laminated body, the battery itself, like the metal can, Although there is no restriction on the degree of freedom in designing the shape of the hardware to be used, a packaging material that can sufficiently satisfy the physical properties and functions required for an exterior body of a lithium ion battery has not yet been developed.

  The physical properties and functions required for the exterior body are high moisture resistance or surface insulation, and moisture resistance is particularly important. The packaging material for a lithium ion battery is a laminate composed of at least a base material layer, a barrier layer, and a heat seal layer, and the material of each layer and the adhesive strength between the layers are necessary as an outer package of a lithium ion battery. It has been confirmed that it affects the properties. For example, if the adhesive strength between the barrier layer and the heat seal layer is insufficient, moisture may enter from the outside, and fluorination generated by the reaction between the electrolyte in the component forming the lithium ion battery and the moisture. There is a problem that dehydration (peeling) occurs between the barrier layer and the heat seal layer due to corrosion of the aluminum surface, which is the barrier layer, due to hydrogen acid, and various proposals have been made for this problem. . When the lithium ion battery main body is sealed with the exterior body, the portion including the tab portion of the lithium ion battery main body needs to be reliably sealed.

  Conventionally, as a method for reliably sealing the tab portion of a lithium ion battery, a heat seal layer having heat and heat fusion properties is selected as a packaging material for a lithium ion battery on a tab made of metal such as aluminum, copper, stainless steel, and nickel. Or, when the heat seal layer does not have heat-fusibility to the metal, heat sealing may be performed by interposing an adhesive film (tab film) in the planned sealing portion of the tab. However, no measures were taken to prevent peeling due to corrosion of the tab surface. Therefore, surface corrosion occurs due to hydrofluoric acid generated in the electrolyte solution as the contents, delamination occurs between the tab and the resin layer laminated on the tab, and the electrolyte solution is exposed to the outside. May leak. Among the tab materials, nickel and stainless steel have a low risk of being corroded by hydrofluoric acid, but aluminum has a problem that it is most easily corroded.

  Therefore, various methods for improving the corrosion resistance of the surface of the tab portion and preventing the separation between the tab and the exterior body have been proposed. For example, Patent Document 1 discloses the front and back surfaces and side surfaces of the tab on which the exterior body is heat-sealed. A method is disclosed in which corrosion of the tab due to hydrofluoric acid is suppressed by phosphoric acid chromate treatment, and wettability (adhesiveness) of the tab surface is improved to improve sealing performance by heat sealing. According to the method of Patent Document 1, the heat seal layer or adhesive film layer that adheres to the tab portion is prevented from peeling off for several years required as the service life of a power source for portable equipment such as a mobile phone, and the sealing performance Can be held.

  By the way, it is known that the lithium ion battery not only has a high output voltage and energy density as described above, but also has high energy efficiency (discharge power / charge power). Is preferable. Therefore, attempts have been made to increase the capacity of lithium ion batteries for power storage such as electric vehicles. If a lithium ion battery is to be used for power storage, it is necessary to store power of several kWh to several tens of kWh.

In that case, since a high voltage is applied to the tub surface as compared with a small lithium ion battery, the chemical conversion treatment layer of Patent Document 1 is eroded by hydrofluoric acid, and a small amount of chromium in the chemical conversion treatment layer is dissolved in the electrolytic solution. There is a possibility that the sealing performance at the seal portion between the tab and the outer package will deteriorate and the positive and negative tabs may short circuit. As the lithium-ion battery becomes larger, the required service life is more than 10 years, so the surface of the tab gradually corrodes over a long period of time, and the outer package or adhesive film layer heat-sealed to the tab peels off. As a result, the sealing system is broken.
JP 2001-307715 A

  In view of the above problems, the present invention provides a tab in which a tab of a lithium ion battery is not corroded by hydrofluoric acid generated by an electrolyte and moisture in a sandwiched portion where the outer body or an adhesive film is bonded. An object of the present invention is to provide a method for forming a surface layer of a tab having corrosion resistance. Another object of the present invention is to provide a lithium ion battery having high durability and safety that ensures sealing performance even after long-term use.

  To achieve the above object, the present invention provides a positive electrode comprising a positive electrode active material and a positive electrode current collector, a negative electrode comprising a negative electrode active material and a negative electrode current collector, and an electrolyte filled between the positive electrode and the negative electrode. Including a lithium ion battery main body, and an exterior body that houses the lithium ion battery main body and seals the lithium ion battery main body by heat-sealing a peripheral portion thereof. A metal lithium-ion battery tab that is connected and sandwiched so that the tip protrudes to the outside by the exterior body, and the sandwiched portion is heat-sealed, and has an insulating resin film on at least the sandwiched portion of the tab An insulating layer comprising: a hydrogen fluoride-resistant chemical conversion treatment layer is provided so as to cover the entire sandwiched portion including the insulating layer. It is a symptom.

  According to the present invention, in the lithium ion battery tab having the above structure, the insulating layer is a heat-resistant polymer having a glass transition point of at least 200 ° C. or more.

  In the invention, it is preferable that the heat-resistant polymer is a polyimide resin, a polyamideimide resin, a polyetherimide resin, or a mixture of two or more thereof.

  According to the present invention, in the lithium ion battery tab having the above structure, the insulating layer is a fluorine-based resin formed from a fluorine-containing copolymer containing a hydroxyl group and a curing agent.

  According to the present invention, in the lithium ion battery tab having the above-described configuration, the chemical conversion treatment layer is formed by a phosphoric acid chromate treatment.

  Moreover, this invention is a lithium ion battery provided with the lithium ion battery tab of the said structure.

  According to the present invention, in the lithium ion battery having the above-described configuration, an adhesive film is interposed between the sandwiched portion and the exterior body.

  The present invention also includes a slitting process in which a metal sheet is slit to a final use width to form a tab material, a degreasing process for degreasing the front and back surfaces and side surfaces of the tab material, and a part of the front and back surfaces and side surfaces of the tab material. A solution obtained by dissolving or dispersing a heat-resistant polymer having a glass transition point of at least 200 ° C. or higher and a coupling agent in a solvent is applied to the surface of the tab material and dried to remove the insulating resin film. An insulating layer forming step for forming an insulating layer, and a chemical conversion treatment step for forming a hydrogen fluoride-resistant chemical conversion treatment layer so as to cover at least the insulation layer.

  The present invention also includes a slitting process in which a metal sheet is slit to a final use width to form a tab material, a degreasing process for degreasing the front and back surfaces and side surfaces of the tab material, and a part of the front and back surfaces and side surfaces of the tab material. An insulating resin obtained by applying a solution obtained by dissolving or dispersing a fluorine-based resin formed from a fluorine-containing copolymer containing a hydroxyl group and a curing agent in a solvent to the surface of the tab material and drying it. A method of manufacturing a lithium ion battery tab, comprising: an insulating layer forming step of forming an insulating layer made of a film; and a chemical conversion treatment step of forming a hydrogen fluoride-resistant chemical conversion treatment layer so as to cover at least the insulating layer. .

  According to the first configuration of the present invention, an insulating layer made of an insulating resin film is provided at least on the sandwiched portion that is bonded to the exterior body or the adhesive film, and further, the entire sandwiched portion is covered with a footproof layer so as to cover the insulating layer. By providing the hydrogenation-type chemical conversion treatment layer, corrosion of the tab due to hydrofluoric acid generated by the electrolyte and moisture is less likely to occur. Therefore, it is possible to provide a lithium ion battery tab having excellent durability that can be applied to a large-sized lithium ion battery that generates a high voltage and has a long service life.

  According to the second configuration of the present invention, in the lithium ion battery tab of the first configuration, the insulating layer is made of a heat resistant polymer having a glass transition point of at least 200 ° C. It can raise more and can prevent the corrosion by hydrofluoric acid reliably.

  According to the third configuration of the present invention, in the lithium ion battery tab of the second configuration, the heat-resistant polymer may be a polyimide resin, a polyamideimide resin, a polyetherimide resin, or two or more thereof. By using this mixture, it is possible to increase the glass transition point of the insulating layer and prevent softening when the secondary battery stores heat.

  According to the fourth configuration of the present invention, in the lithium ion battery tab of the first configuration, the insulating layer is a fluororesin formed from a fluorine-containing copolymer containing a hydroxyl group and a curing agent. As a result, the insulating property of the tab can be further increased and corrosion due to hydrofluoric acid can be reliably prevented.

  Further, according to the fifth configuration of the present invention, in the lithium ion battery tab having any one of the first to fourth configurations, the chemical conversion treatment layer is formed by the phosphoric acid chromate treatment. And a lithium ion battery tab having a chemical conversion treatment layer having both heat resistance and stable heat sealability with the inner surface of the exterior body.

  Moreover, according to the sixth configuration of the present invention, by using the lithium ion battery tab having any one of the first to fifth configurations in which the corrosion resistance of the tab surface is improved by forming an insulating film, It is possible to provide a lithium ion battery with high durability and safety in which sealing performance is ensured even during a period of use.

  Further, according to the seventh configuration of the present invention, in the lithium ion battery of the sixth configuration, the adhesive film is interposed between the tab sandwiching portion and the exterior body, thereby being adhered to the inner surface of the exterior body. Heat-sealing property can be imparted to the sandwiched portion without laminating the layers, and sealing with the exterior body is possible in a stable state.

  Moreover, according to the 8th structure of this invention, after slitting a metal sheet to the last use width | variety and making it the tab material of a elongate state, degreasing the front and back and side surface of a tab material, By applying a part of the side surface, which is a solution obtained by dissolving or dispersing a heat-resistant polymer having a glass transition point of at least 200 ° C. and a coupling agent in a solvent to the surface of the tab material, and then drying. Corrosion by hydrofluoric acid generated by electrolyte and moisture by forming an insulating layer composed of an insulating resin film and forming a hydrofluoric acid-resistant chemical conversion treatment layer so as to cover the entire sandwiched portion including the insulating layer Therefore, it is possible to easily and inexpensively manufacture a lithium ion battery tab having excellent durability.

  Further, according to the ninth configuration of the present invention, after slitting the metal sheet to the final use width to make the tab material in a long state, the front and back surfaces and side surfaces of the tab material are degreased, and the front and back surfaces of the tab material and A part of the side surface is dissolved or dispersed in a solvent to form a fluorine-based resin formed from a fluorine-containing copolymer containing a hydroxyl group and a curing agent, and then applied to the surface of the tab material and dried. By forming an insulating layer made of an insulating resin film, and forming a hydrofluoric acid-resistant chemical conversion treatment layer so as to cover the entire sandwiched portion including the insulating layer, hydrofluoric acid generated by the electrolyte and moisture Therefore, it is possible to easily and inexpensively manufacture a lithium ion battery tab with excellent durability and corrosion resistance.

  Hereinafter, the manufacturing method of the lithium ion battery tab of this invention and a tab material is demonstrated, referring drawings. FIG. 1A is a perspective view of a lithium ion battery of the present invention, and FIG. 1B is a perspective view showing a state in which the lithium ion battery is disassembled. As shown in FIGS. 1A and 1B, a lithium ion battery 1 is composed of a lithium ion battery body 2 and an exterior body 5, and the lithium ion battery body 2 housed in the exterior body 5 is By sealing the periphery, moisture resistance is imparted.

  The lithium ion battery body 2 includes 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 (none shown). And a tab (electrode terminal) 4 that is connected to a positive electrode and a negative electrode in the cell 3 and has a tip projecting outside the exterior body 5. The tab 4 is made of aluminum and has a thickness of about 50 to 200 μm and a width of about 5 to 100 mm.

  FIG. 2 is an enlarged cross-sectional view showing the structure around the tab of the lithium ion battery. Portions common to FIG. 1 are denoted by the same reference numerals and description thereof is omitted. The exterior body 5 has a laminated structure composed of a plurality of layers, and a metal adhesive film is laminated as the innermost layer 14 to enhance the heat sealability between the metal tab 4 and the exterior body 5. The outer package 5 in which the innermost layer 14 does not have heat sealability with respect to the metal may be used. In that case, both the metal tab 4 and the innermost layer of the outer package 5 have heat sealability. It heat-seals and welds through an adhesive film (refer FIG. 5, FIG. 6).

  An insulating layer 4b (not shown) made of an oxide film is provided on the portion of the tab 4 where the outer package 5 is heat-sealed (hereinafter referred to as a sandwiching portion) 7 and the portion disposed inside the outer package 5 and in contact with the electrolyte. And a chemical conversion treatment layer 4c made of a hydrogen fluoride resistant layer. A positive electrode current collector 8 that electrically connects a positive electrode (not shown) and the tab 4 is coupled to the tip of the tab 4 housed in the exterior body 5. In addition, although the structure around the tab on the positive electrode side has been described here, the negative electrode side has the same configuration. The detailed configuration of the exterior body 5 will be described later.

  The present invention is characterized in that an insulating layer 4b made of an insulating resin film is provided on at least the sandwiching portion 7 of the metal tab 4, and a chemical conversion treatment layer 4c is further provided. With this configuration, the dissolution and corrosion of the tab surface due to hydrogen fluoride (chemical formula: HF) generated by the reaction between the electrolyte of the lithium ion battery and moisture is prevented, and the innermost layer or the adhesive film of the outer package 5 It is possible to improve the adhesiveness (wetting property) with the tab 4 and to stabilize the adhesive force in the tab.

  The lithium ion battery has a pouch type using a pillow-shaped exterior body 5 as shown in FIG. 1 and an embossed portion as shown in FIG. 3 depending on the type of exterior body that wraps the lithium ion battery body. There is an embossed type in which the lithium ion battery main body 2 is hermetically housed using an exterior body 5 composed of a tray 5a and a sheet 5b, but the present invention can be applied to any type.

  Next, the configuration of the tab will be described in detail. 4A is a cross-sectional view of the lithium-ion battery tab (XX cross-section in FIG. 1), FIG. 4B is a cross-sectional view in a state of being housed in the exterior body, and FIG. 4C is a tab view of the exterior body. It is sectional drawing in the state heat-sealed with. Portions common to FIGS. 1 and 2 are denoted by the same reference numerals and description thereof is omitted. As shown in FIG. 4, the tab 4 has an insulating layer 4 b formed on the sandwiched portion of the tab material 4 a having a predetermined width and on the inside of the exterior body 5 and in contact with the electrolyte solution, and further on the outside of the insulating layer 4 b. The chemical conversion treatment layer 4c is laminated. An opening 4d is formed in the insulating layer 4b, and the tab member 4a is in contact with the chemical conversion treatment layer 4c through the opening 4d.

  The insulating layer 4b is formed by applying a solution containing an insulating resin to a predetermined portion of the surface of the tab material 4a formed of a metal foil such as an aluminum foil, a copper foil (including nickel plating), or a nickel foil. It is what. As a method for forming the insulating resin film, (1) a method of applying and drying a solution containing a heat-resistant polymer having a glass transition point of at least 200 ° C. and a coupling agent, and (2) fluorine containing a hydroxyl group. And a method of applying and drying a solution obtained by dissolving or dispersing a fluorine-based resin formed by a containing copolymer and a curing agent that reacts with a hydroxyl group of the fluorine-containing copolymer into a solvent. Can be used. Hereinafter, each method will be described.

  First, the method (1) will be described. As the heat-resistant polymer having a glass transition point of at least 200 ° C., conventionally known polyimide resins, polyamideimide resins or polyetherimide resins are used alone or in combination. It is preferable to use a glass transition point of 260 ° C. or higher. The reason for using a heat-resistant polymer having a high glass transition point is to prevent the secondary battery from being softened when the heat is stored. On the other hand, as the coupling agent, conventionally known silane coupling agents, titanate coupling agents, aluminum coupling agents, and the like are used. This coupling agent is used to improve the adhesion between the insulating layer and the metal foil and the adhesion between the insulating layer and the chemical conversion treatment skin layer.

  A solution in which such a heat-resistant polymer and a coupling agent are dissolved or dispersed in a solvent is used. As the solvent, it is preferable to use a polar solvent such as N-methyl-2-pyrrolidone, N, N-dimethylformamide, tetrahydrofuran or the like that easily dissolves the heat-resistant polymer. The insulating layer 4b can be obtained by applying such a solution to the surface of the tab material 4a and drying (baking). The drying (baking) conditions are preferably about 180 to 250 ° C., and the time is preferably 5 to 50 seconds.

Next, the method (2) will be described. The fluorine-containing copolymer containing a hydroxyl group is soluble in an organic solvent and has a crosslinking site in the molecule, and examples of the crosslinking site include an alcoholic hydroxyl group (OH group). As such a fluorine-containing copolymer, for example, 1) a fluoroolefin monomer represented by the formula: CF ₂ = CFX [wherein X is a fluorine atom, a hydrogen atom or a trifluoromethyl group], 2) β-methyl substituted α-olefin monomer represented by the formula: CH ₂ = CR (CH ₂ ) [wherein R is an alkyl group having 1 to 8 carbon atoms], 3) Formula: CH ₂ = CHR1 [wherein R1 is —OR2 or —CH ₂ OR2 (where R2 is an alkyl group having a hydroxyl group)], and 4) has a crosslinkable functional group And fluorine-containing copolymers derived from other monomers that can be copolymerized with the monomers 1), 2), and 3).

  Examples of the fluoroolefin monomer include tetrafluoroethylene, trifluoroethylene, hexafluoropropylene, and the like. Examples of the β-methyl substituted α-olefin monomer include isobutylene, 2-methyl-1-pentene, 2-methyl-1-hexene and the like. Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl vinyl ether, 3-hydroxypropyl vinyl ether, 2-hydroxypropyl vinyl ether, 2-hydroxy-2-methylpropyl vinyl ether, 4-hydroxybutyl vinyl ether, and 5-hydroxypentyl. Examples include vinyl ether, 6-hydroxyhexyl vinyl ether, 2-hydroxyethyl allyl ether, 4-hydroxybutyl allyl ether, and the like. Examples of other monomers that can be copolymerized with the fluoroolefin monomer, the β-methyl-substituted α-olefin monomer, and the hydroxyl group-containing monomer include vinyl acetate, vinyl propionate, (iso ) Carboxylic acid vinyl esters such as vinyl butyrate, vinyl caproate, vinyl laurate, vinyl stearate, vinyl benzoate, vinyl xafluoropropionate, vinyl trifluoroacetate, maleic acid or dimethyl fumarate, diethyl, dipropyl, dibutyl, Alkyl vinyl such as diester of maleic acid or fumaric acid such as ditrifluoromethyl, ditrifluoromethyl, dihexafluoropropyl, methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, iso-butyl vinyl ether, tert-butyl vinyl ether In addition to ruethers, cycloalkyl vinyl ethers such as cyclopentyl vinyl ether and cyclohexyl vinyl ether, vinyl ethers having aromatic groups such as benzyl vinyl ether, or fluoroalkyl vinyl ethers such as perfluoroethyl vinyl ether and perfluoropropyl vinyl ether, etc. Vinyl acetate, maleic acid, styrene and the like.

  The fluorine-containing copolymer having a hydroxyl group can be obtained by copolymerizing the monomers 1) to 4) by a known method such as emulsion polymerization, solution polymerization, suspension polymerization or the like. The fluorine-containing copolymer having a hydroxyl group has a number average molecular weight measured by GPC of 1,000 to 500,000, preferably 3,000 to 100,000.

  As the curing agent, an organic polyisocyanate compound having high reactivity with a hydroxyl group as a crosslinking site is suitable, for example, 2,4-tolylene diisocyanate, diphenylmethane-4,4′-diisocyanate, xylylene diisocyanate. , Isophorone diisocyanate, lysine methyl ester diisocyanate, methylcyclohexyl diisocyanate, trimethylhexamethylene diisocyanate, hexamethylene diisocyanate, n-pentane-1,4-diisocyanate, and trimers thereof, adducts and burettes thereof, or Examples of these polymers include those having two or more isocyanate groups, and blocked isocyanates.

Such a fluorine-containing copolymer containing a hydroxyl group is reacted with a curing agent to form a fluorine resin. For example, the said fluorine-containing copolymer is melt | dissolved in a solvent, 0.1-5.0 equivalent with respect to 1 equivalent of hydroxyl groups (-OH group) in this fluorine-containing copolymer, Preferably 0.5-1. The said hardening | curing agent is added so that it may become 5 equivalent. A solution obtained by dissolving or dispersing the fluororesin thus obtained in a solvent is applied to the surface of the tab material 4a using a known application method such as a roll coating method, a gravure coating method, or a bar coating method. Then, the insulating layer 4b can be obtained by drying. The amount of the fluororesin applied is suitably 3.0 to 5.0 g / m ² after drying. The reason is that 3.0 g / m ² or more is necessary for securing the laminate strength, and 5.0 g / m ² or less is appropriate in consideration of moisture permeation from the end face and cost.

  The insulating layer 4b may be directly formed on the surface of the tab material 4a not subjected to any treatment as described above, but in order to improve the adhesion between the tab material 4a and the insulating layer 4b, It is desirable to form a metal-adhesive olefin resin layer on the surface of the tab material 4a, and to form the insulating layer 4b through the metal-adhesive olefin resin layer. In this case, the exposed surface of the metal-adhesive olefin resin layer is subjected to easy adhesion treatment such as corona discharge treatment, ozone treatment, and plasma treatment in consideration of adhesion with the fluorine resin layer.

  Examples of the metal-adhesive olefin resin include acid-modified polyolefin resins, for example, polyolefin resins graft-modified with unsaturated carboxylic acid, acid-modified polyolefin resins such as ethylene or propylene and acrylic acid, or a copolymer of methacrylic acid. Particularly preferred is a polyolefin resin graft-modified with an unsaturated carboxylic acid. This is because a polyolefin resin graft-modified with an unsaturated carboxylic acid is superior in heat resistance compared to an acid-modified polyolefin resin such as a copolymer of ethylene or propylene and acrylic acid or methacrylic acid. The thickness of the metal-adhesive olefin resin layer 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 is large. This is because the battery performance may be reduced.

  If the insulating layer 4b is formed on the entire surface of the tab member 4a, the discharge from the cell 3 and the recharge to the cell 3 cannot be performed via the tab 4. Therefore, an opening 4d is provided at a predetermined location of the insulating layer 4b, and electrons are exchanged between the cell 3 and the tab material 4a through the opening 4d and the chemical conversion treatment layer 4c. The opening 4d may be provided in a pattern as shown in FIG. 4, or may be provided only in a portion where the positive electrode current collector 8 (see FIG. 2) is connected.

  The chemical conversion treatment layer 4c is formed by performing chemical conversion treatment (hereinafter referred to as phosphoric acid chromate treatment) with chromium phosphate, chromic acid, or the like on the sandwiched portion 7 on the surface of the tab material 4a and the portion in contact with the electrolytic solution. The The chemical conversion treatment layer 4c and the insulating layer 4b described above effectively prevent corrosion and dissolution of the tab surface due to hydrofluoric acid generated by the reaction between the electrolyte component in the lithium ion battery and moisture entering from the outside. To do. Furthermore, the chemical conversion treatment layer 4 c also has an action of reliably heat-sealing the innermost layer 14 (see FIG. 5) of the outer package 5 or the adhesive film 6 (see FIG. 6) to the tab 4 and the tab 4.

  Next, the manufacturing method of the lithium ion battery tab of this invention is demonstrated. First, an aluminum sheet for tab production is slit into a long tab material having a final use width using a slitter (slit process). Next, the front and back surfaces and side surfaces of the tab material slit to a predetermined width are degreased (degreasing step). Thereafter, an insulating layer made of an insulating resin film is formed at a predetermined portion of the tab material (a sandwiched portion and a portion in contact with the electrolytic solution) (insulating layer forming step). Finally, a hydrogen fluoride-resistant chemical conversion treatment layer is formed so as to cover the entire sandwiched portion including the insulating layer (chemical conversion treatment step), and the lithium ion battery tab is manufactured by cutting into a predetermined length.

  When forming an aluminum sheet as a raw material for the tab material, oily components may adhere to the surface, and when cutting from a wide sheet to a tab material of a predetermined width by a slitter, to protect the cutting blade Oil used in the case may adhere. Since these oil components and oil adversely affect the subsequent formation of the insulating layer and the chemical conversion treatment layer, a degreasing process for removing the oil components and oil is necessary. In addition, before the degreasing step, a step of pretreating the surface of the tab material by buffing or the like may be provided, and a step of cleaning and dissolving the surface of the tab material by etching, desmut treatment or the like may be further provided.

  The degreasing treatment can be performed by coating the tab material with an acid or an alkali solution, or immersing the tab material in an acid or an alkali solution. Acidic substances used for degreasing include inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, hydrofluoric acid, phosphoric acid, sulfamic acid, citric acid, gluconic acid, oxalic acid, tartaric acid, formic acid, hydroxyacetic acid, EDTA (ethylenediaminetetraacetic acid) and Examples thereof include ammonium derivatives and ammonium thioglycolate.

Examples of alkaline substances include caustic soda (NaOH), soda ash (Na ₂ CO ₃ ), sodium bicarbonate (NaHCO ₃ ), bow glass (Na ₂ SO ₄ .10H ₂ O), sesquicarbonate (Na ₂ CO ₃ .NaHCO ₃ ). ₃ · 2H ₂ O) soda salts such as, orthosilicate Cao _{(2Na 2 O · S I O} 2, 10~40% moisture), metasilicate Cao _{(2Na 2 O · S I O} 2 · 9H 2 O), one silicate No. Cao _{(Na 2 O · 2S I O} 2, water 42 to 44%), two items silicate soda _{(Na 2 O · 3S I O} 2, 65% moisture) silicates such as, primary phosphate sodium (NaH ₂ PO ₄ ), sodium pyrophosphate (Na ₄ P ₂ O ₇ ), sodium diphosphate (Na ₂ HPO ₄ ), sodium hexametaphosphate {(NaPO ₃ ) ₆ }, sodium triphosphate (Na ₃ PO ₄ ) phosphate salts such as sodium tripolyphosphate (Na ₅ P ₃ O ₁₀₎ And the like.

  The insulating layer forming step is formed from a solution obtained by dissolving or dispersing a heat-resistant polymer and a coupling agent in a solvent as described above, or a fluorine-containing copolymer containing a hydroxyl group and a curing agent. A solution obtained by dissolving or dispersing a fluorine-based resin in a solvent can be applied to the surface of the tab material 4a and dried (baked). Note that the type of solvent, the coating method, the drying (baking) method, and the like may be selected so as to satisfy the optimum conditions according to the required layer thickness and quality of the insulating layer.

  As described above, in order to ensure the conductivity of the tab, it is necessary to form an opening (see FIG. 4) in which the surface of the tab material is exposed in the insulating resin film. As a method for forming the opening, a resist film is formed in a pattern corresponding to the opening in advance by printing or the like, and after treatment with an acidic or alkaline electrolytic solution only in a necessary portion, the resist film is removed and insulated. And a method of forming an insulating resin film on the entire surface by immersing the entire surface in an acidic or alkaline electrolytic solution and then scraping off unnecessary portions.

  In the chemical conversion treatment step, a solution composed of phosphate, chromate, fluoride, and triazine thiol compound is applied to the surface of the tab material, and the film is dried and cured by heating, irradiation with near infrared rays, etc. to form a chemical conversion treatment layer. Is. In particular, a phosphoric acid chromate treatment using an aqueous solution composed of a phenol resin, a chromium (III) fluoride compound and phosphoric acid is suitably used as the treatment liquid.

The chemical conversion treatment method is not limited as long as it can treat the sandwiched portion and the portion in contact with the electrolytic solution in the tab portion, but the immersion method in which the tab material is immersed in the chromate solution, the shower method in which the chromate solution is sprayed on the tab material, roll It is desirable to treat the entire periphery of the tab material using a roll coating method or the like that coats the tab material with a chromate solution. Thereafter, the chromate solution applied to the tab material is dried, and further subjected to chemical conversion treatment on the front and back surfaces and side surfaces of the tab material by baking under a temperature condition where the film temperature is 180 ° C. or higher. The coating amount of chromate solution is suitably about ^{2 to} 20 mg / m ² (dry weight).

  Next, the material of the exterior body used for the lithium ion battery of this invention is demonstrated. As shown in FIG. 5A, the laminate 10 forming the exterior body includes at least a base material layer 11, a barrier layer 12, and an innermost layer (heat seal layer) 14, and an adhesive layer 16 is provided between these layers. And laminating by a method such as a dry laminating method, a sandwich laminating method, an extrusion laminating method, or a thermal laminating method. Further, as shown in FIG. 5B, an intermediate layer 13 may be provided between the barrier layer 12 and the innermost layer 14.

  The outermost layer is made of stretched polyester or nylon film, and examples of the polyester resin include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, copolymerized polyester, and polycarbonate. Examples of the nylon resin include polyamide resins such as nylon 6, nylon 6,6, copolymers of nylon 6,6 and nylon 6, nylon 6,10, polymetaxylylene adipamide (MXD6), and the like. It is done.

  When the outermost layer is used as a lithium ion battery, the outermost layer is a portion that is in direct contact with the hardware, and thus a resin layer having insulating properties is basically preferable. Considering the existence of pinholes in a single film and the occurrence of pinholes during processing, the outermost layer needs to have a thickness of 6 μm or more, and a preferred thickness is 12 to 25 μm.

The outermost layer may be laminated in order to improve pinhole resistance and insulation when used as a battery outer package. When the outermost layer is laminated, the outermost layer includes at least one resin layer of two or more layers, and the thickness of each layer is 6 μm or more, preferably 12 to 25 μm. Examples of laminating the outermost layer include the following 1) to 7) although not shown.
1) Stretched polyethylene terephthalate / stretched nylon 2) Stretched nylon / stretched polyethylene terephthalate

In addition, the packaging material mechanical suitability (stability of conveyance in packaging machines and processing machines), surface protection (heat resistance and electrolyte resistance), and secondary processing embossed lithium ion battery exterior body (Refer to Fig. 3) For the purpose of reducing the frictional resistance between the mold and the outermost layer during embossing, the outermost layer is multi-layered, and the surface of the outermost layer is a fluororesin layer, an acrylic resin layer, a silicone system. It is preferable to provide a resin layer or the like. For example,
3) Fluorine resin / stretched polyethylene terephthalate (Fluorine resin is a film or formed by drying after liquid coating)
4) Silicone resin / stretched polyethylene terephthalate (silicone resin is a film or formed by drying after liquid coating)
5) Fluorine-based resin / stretched polyethylene terephthalate / stretched nylon 6) Silicone-based resin / stretched polyethylene terephthalate / stretched nylon 7) Acrylic resin / stretched nylon (Acrylic resin is film-like or cured after drying by liquid coating)

  As a laminating method for forming the outer package having a laminated structure, a dry laminating method, a thermal laminating method, an extrusion laminating method, a sandwich laminating method, a coextrusion laminating method, or the like can be used.

  The barrier layer 12 is a layer for preventing water vapor from entering the inside of the lithium ion battery from the outside through the exterior body 5, and stabilizes pinholes and processability (pouching, embossing) of the barrier layer alone. For example, a film having a thickness of 15 μm or more, such as aluminum or nickel, or a film on which an inorganic compound such as silicon oxide or alumina is deposited is preferable. Is aluminum of 15 μm to 100 μm.

  By using aluminum having an iron content of 0.3 to 9.0% by weight, preferably 0.7 to 2.0% by weight, as a material for the barrier layer, compared to aluminum not containing iron, Aluminum has good spreadability, and the laminated body is less likely to generate pinholes due to bending, and the side wall can be easily formed when embossing an embossed type exterior body. When the iron content is less than 0.3% by weight, effects such as prevention of pinholes and improvement in embossing formability are not observed, and the iron content of the aluminum is 9.0% by weight. When exceeding, the softness | flexibility as aluminum is inhibited and bag-making property worsens as a laminated body.

  In addition, aluminum produced by cold rolling changes its flexibility, waist strength, and hardness under annealing (so-called annealing treatment) conditions, but the aluminum used in this example is not annealed. A soft processed product having flexibility, which is appropriately annealed, is preferable to the product. The degree of flexibility, waist strength and hardness, that is, annealing conditions may be appropriately selected in accordance with processing suitability (pouching, embossing suitability). For example, in order to prevent pinholes and wrinkles during embossing, aluminum that tends to be softer and more or less annealed than hard aluminum that has not been annealed is better.

  Furthermore, a chemical conversion treatment layer 15 made of an oxide film is provided on the surface of the barrier layer 12. The chemical conversion treatment layer 15 prevents the corrosion and dissolution of the surface of the barrier layer 12 due to hydrogen fluoride generated by the electrolyte and moisture of the lithium ion battery, and improves the adhesion (wetting property) of the surface of the barrier layer 12 to provide a laminate. The adhesive force between the barrier layer 12, the base material layer 11, and the innermost layer 14 (or the intermediate layer 13) at the time of formation is stabilized.

  The innermost layer of the outer package used in the present invention is a material in which the innermost layers have heat-sealing properties and also show heat-sealing properties with respect to the metal forming the tab, and are not altered or deteriorated by the contents. As a result, the unsaturated carboxylic grafted polyethylene, the unsaturated carboxylic grafted polypropylene, the unsaturated carboxylic grafted polymethyl having a thickness of 10 μm or more, preferably 20 to 100 μm, a melting point of 80 ° C. or more, and a Vicat softening point of 70 ° C. or more. An unsaturated carboxylic graft polyolefin resin such as pentene, a metal ion cross-linked polyethylene, or a copolymer of ethylene or propylene and acrylic acid or methacrylic acid, and those containing at least one of these modified products give good results. Indicated.

  For the innermost layer, a polyolefin having no metal adhesion can also be used. In this case, an unsaturated carboxylic graft polyolefin, a metal-crosslinked polyethylene, ethylene or propylene and acrylic acid, between the electrode and the innermost layer, Alternatively, by using a heat-adhesive tab material (thickness of 15 μm or more) formed from a copolymer with methacrylic acid, the tab and the packaging material can be completely bonded and sealed. By interposing the adhesive film 6 between the tab 4 and the innermost layer 14, sealing performance can be ensured.

  As the adhesive film, it is more preferable to use a film in which a polyolefin layer in which at least one is an acid-modified polyolefin is laminated on both surfaces of a biaxially stretched polyethylene naphthalate film. In this case, since the polyethylene naphthalate film is excellent in heat resistance, it is not thinned during heat sealing, and a short circuit between the barrier layer 12 and the tab 4 can be prevented.

  As shown in FIGS. 6 (a), 6 (b), and 6 (c), the adhesive film is set on the heat seal portion between the tab 4 and the innermost layer 14 with the tab 4 (metal). ) And the innermost layer 14 (heat seal layer) may be provided with an adhesive film 6 having a sealing property, and FIGS. 7 (a), 7 (b), and 7 (c). As shown in FIG. 5, the tab 4 may be wound around a predetermined position. Examples of the adhesive film 6 include an unsaturated carboxylic acid grafted polyolefin obtained by graft-modifying a polyolefin resin with an unsaturated carboxylic acid, a metal-crosslinked polyethylene, a film made of a copolymer of ethylene or propylene and acrylic acid, or methacrylic acid. Can be used. In addition, the innermost layer 14 in the laminated body of the present invention may be a single layer made of the above resin, or may be two or more layers including the above resin.

  The unsaturated carboxylic graft polyolefin resin is suitable for any of adhesion to electrodes, heat resistance, cold resistance, and processability (pouching, embossing formability). If the thickness of the innermost layer is less than 20 μm, when the electrode is heat-sealed, a gap is formed at the end portion and the barrier property is lost. Moreover, even if the thickness of the innermost layer exceeds 100 μm, the heat seal strength does not change, and the thickness of the laminated body increases, which goes against the space-saving that is the subject of the present invention. Moreover, when melting | fusing point and Vicat softening point are low, heat resistance and cold resistance will lose | eliminate, the adhesive strength with films and an electrode will fall, and a bag will break. The various unsaturated carboxylic graft polymers may be used alone, but the properties can also be satisfied by blending two or more kinds of resins.

  For each layer of the laminate of the present invention, corona treatment and blast treatment are appropriately performed for the purpose of improving and stabilizing film forming properties, lamination processing, and final product secondary processing (pouching, embossing) suitability. Surface activation treatment such as oxidation treatment or ozone treatment may be performed.

  The outermost layer, the barrier layer, the intermediate layer, and the innermost layer of the laminate of the present invention are formed, or the lamination method between the layers is specifically a T-die method, an inflation method, a coextrusion method, or the like. To form a film. If necessary, the secondary film may be formed by a method such as coating, vapor deposition, ultraviolet curing, or electron beam curing. Moreover, as a bonding method, methods such as a dry laminating method, an extrusion laminating method, a coextrusion laminating method, and a thermal laminating method can be used.

  When laminating by the dry laminating method, polyester, polyethyleneimine, polyether, cyanoacrylate, urethane, organic titanium, polyetherurethane, epoxy, polyesterurethane, imide, isocyanate Various adhesives based on polyolefin, polyolefin, and silicone can be used. In addition, these adhesive layers appropriately contain at least one of silicon oxide, calcium carbonate, zinc, red lead, lead suboxide, lead oxide, lead cyanamide, zinc chromate, barium potassium chromate, and barium zinc chromate. It is possible to further improve chemical resistance and organic solvent resistance by adding an additive characterized by the above. In particular, silicon oxide, calcium carbonate, zinc, red lead, lead suboxide, zinc oxide, lead cyanamide, zinc chromate, potassium barium chromate, barium zinc chromate, etc. are generated by the reaction of electrolyte with moisture Has the effect of preventing the corrosion of hydrogen fluoride on each layer, particularly the barrier layer (aluminum).

  Moreover, when using the extrusion laminating method, as an adhesion promoting method for stabilizing the adhesive force between each layer to be bonded, polyester-based, polyether-based, urethane-based, polyether-urethane-based, polyester-urethane-based, isocyanate-based, polyolefin-based, Apply a resin such as polyethyleneimine, cyanoarylate, organotitanium compound, epoxy, imide, silicone, and their modified products, or a mixture of about 1 μm, or perform surface activation treatment by ozone treatment. be able to. Further, by using an unsaturated carboxylic acid grafted polyolefin as a resin when bonded by an extrusion laminating method or a thermal laminating method, adhesion resistance and content resistance are improved.

The lithium ion battery tab and the tab material chemical conversion treatment method of the present invention will be described with reference to examples. The common conditions in the following Examples 1 to 4 are as follows.
(1) The tab has nickel as the anode and aluminum as the cathode, and each has a width of 8 mm, a length of 50 mm, and a thickness of 100 μm.
(2) The pouch type was a pillow type, and the pouch size was an outer size, with a width of 60 mm and a length of 80 mm (both seal widths were 5 mm).
(3) The embossed type was a single-sided embossed type, the recess was 35 mm × 50 mm, the depth of the recess was 3.5 mm, and the width of the flange part (seal part) was 5 mm.
(4) The tab degreasing treatment, anodizing treatment, and chemical conversion treatment in the examples were performed on the sheet cut to the size to be attached to the lithium ion battery main body. In actual manufacturing, as described above, the metal sheet of the tab material can be processed in a slit state.

(Pouch type)
1. (Degreasing step) Prepare a 30 μm thick aluminum foil as the cathode tab material and a 30 μm thick nickel foil as the anode tab material, and immerse these tab materials in 0.1 N nitric acid solution for 5 minutes. After washing with water and drying.
2. (Insulating layer forming step) As an insulating varnish, one comprising 20 parts by weight of an aromatic polyamideimide resin, 3 parts by weight of a silane coupling agent, and 80 parts by weight of a mixed solvent composed of N-methyl-2-pyrrolidone and xylene is prepared. Then, after forming a resist film on both sides of the tab material, the insulating varnish is applied with a bar coater, dried (baked) at 190 ° C. for 10 seconds, washed with water, and the resist film is removed. An insulating layer having a predetermined pattern thickness of 2 μm was formed on both sides.
3. (Chemical conversion treatment process) After performing corona discharge treatment on both surfaces of the tab material on which the insulating layer is formed, a roll coating method using a chemical conversion treatment liquid containing an aminated phenol polymer, a trivalent chromium compound, and a phosphorus compound Thus, a 2 μm chemical conversion treatment layer was formed. The tab material for anode and cathode thus obtained was joined to the cell end portion of the lithium ion battery to obtain a battery body.
4). The laminated body which forms an exterior body was created as follows. Chemical conversion treatment is applied to one side of 20 μm aluminum, and a stretched polyester film (thickness: 16 μm) is bonded to the surface not subjected to chemical conversion by a dry lamination method. Next, acid modification is applied to the surface of the chemical conversion treatment aluminum and the chemical conversion treatment layer. A pouch was formed using a laminate obtained by laminating 50 μm of a polypropylene film by dry lamination to obtain an outer package.
5. The battery main body was housed in the outer package, and the unsealed portion of the main body example was heat sealed together with the tab to obtain a pouch-type lithium ion battery.

(Pouch type)
1. (Degreasing step) Prepare a 30 μm thick aluminum foil as the cathode tab material and a 30 μm thick nickel foil as the anode tab material, and immerse these tab materials in 0.1 N nitric acid solution for 5 minutes. After washing with water and drying.
2. (Insulating layer forming step) After forming a resist film on both sides of the tab material, polypropylene (hereinafter referred to as PPa) graft-modified with unsaturated carboxylic acid is heated and melted with a T-die extruder so as to have a thickness of 15 μm. The PPa surface was extruded and then subjected to a corona discharge treatment, and the PPa surface treated with the corona discharge was treated with a fluorine-based polyol and an isocyanate-based curing agent at 1.1 equivalents relative to 1 equivalent of a hydroxyl group (-OH group) of the polyol. The thus added fluororesin solution was applied and dried to 3.0 g / m ² after drying, and after washing with water, the resist film was removed to form insulating layers having a predetermined pattern on both sides of the tab material. .
3. (Chemical conversion treatment process) After performing corona discharge treatment on both surfaces of the tab material on which the insulating layer is formed, a roll coating method using a chemical conversion treatment liquid containing an aminated phenol polymer, a trivalent chromium compound, and a phosphorus compound Thus, a 2 μm chemical conversion treatment layer was formed. The tab material for anode and cathode thus obtained was joined to the cell end portion of the lithium ion battery to obtain a battery body.
4). The laminated body which forms an exterior body was created as follows. Chemical conversion treatment is applied to one side of 20 μm aluminum, and a stretched polyester film (thickness: 16 μm) is bonded to the surface not subjected to chemical conversion by a dry lamination method. Next, acid modification is applied to the surface of the chemical conversion treatment aluminum and the chemical conversion treatment layer. A pouch was formed using a laminate obtained by laminating 50 μm of a polypropylene film by dry lamination to obtain an outer package.
5. The battery main body was housed in the outer package, and the unsealed portion of the main body example was heat sealed together with the tab to obtain a pouch-type lithium ion battery.

(Embossed type)
1. (Degreasing step) Prepare a 30 μm thick aluminum foil as the cathode tab material and a 30 μm thick nickel foil as the anode tab material, and immerse these tab materials in 0.1 N nitric acid solution for 5 minutes. After washing with water and drying.
2. (Insulating layer forming step) As an insulating varnish, one comprising 20 parts by weight of an aromatic polyamideimide resin, 3 parts by weight of a silane coupling agent, and 80 parts by weight of a mixed solvent composed of N-methyl-2-pyrrolidone and xylene is prepared. Then, after forming a resist film on both sides of the tab material, the insulating varnish is applied with a bar coater, dried (baked) at 190 ° C. for 10 seconds, washed with water, and the resist film is removed. An insulating layer having a predetermined pattern thickness of 2 μm was formed on both sides.
3. (Chemical conversion treatment process) After performing corona discharge treatment on both surfaces of the tab material on which the insulating layer is formed, a roll coating method using a chemical conversion treatment liquid containing an aminated phenol polymer, a trivalent chromium compound, and a phosphorus compound Thus, a 2 μm chemical conversion treatment layer was formed. The tab material for anode and cathode thus obtained was joined to the cell end portion of the lithium ion battery to obtain a battery body.
4). Chemical conversion treatment was applied to both sides of 40 μm aluminum, and a stretched nylon film (thickness 25 μm) was bonded to one side of the chemical conversion treatment by dry lamination, and then MDPE was heat sealed to the other side of the chemical conversion treatment aluminum. It is obtained by extruding as a molten resin film having a thickness of 30 μm as a layer, extruding and laminating the laminated surface with aluminum of the molten resin film to form a laminate, and then heating it above the softening point of MDPE. The laminate was embossed using the laminate, and the lid was cut into a predetermined size without molding to obtain an exterior body.
5. As an adhesive film, with the tabs sandwiched by acid-modified LLDPE 100 μm, the battery body is housed in the embossed part of the exterior body, the lid is covered and the periphery is heat-sealed to form an embossed lithium ion battery. Obtained.

(Embossed type)
1. (Degreasing step) Prepare a 30 μm thick aluminum foil as the cathode tab material and a 30 μm thick nickel foil as the anode tab material, and immerse these tab materials in 0.1 N nitric acid solution for 5 minutes. After washing with water and drying.
2. (Insulating layer forming step) After forming a resist film on both sides of the tab material, polypropylene (hereinafter referred to as PPa) graft-modified with unsaturated carboxylic acid is heated and melted with a T-die extruder so as to have a thickness of 15 μm. The PPa surface was extruded and then subjected to a corona discharge treatment, and the PPa surface treated with the corona discharge was treated with a fluorine-based polyol and an isocyanate-based curing agent at 1.1 equivalents relative to 1 equivalent of a hydroxyl group (-OH group) of the polyol. The thus added fluororesin solution was applied and dried to 3.0 g / m ² after drying, and after washing with water, the resist film was removed to form insulating layers having a predetermined pattern on both sides of the tab material. .
3. (Chemical conversion treatment process) After performing corona discharge treatment on both surfaces of the tab material on which the insulating layer is formed, a roll coating method using a chemical conversion treatment liquid containing an aminated phenol polymer, a trivalent chromium compound, and a phosphorus compound Thus, a 2 μm chemical conversion treatment layer was formed. The tab material for anode and cathode thus obtained was joined to the cell end portion of the lithium ion battery to obtain a battery body.
4). Chemical conversion treatment was applied to both sides of 40 μm aluminum, and a stretched nylon film (thickness 25 μm) was bonded to one side of the chemical conversion treatment by dry lamination, and then MDPE was heat sealed to the other side of the chemical conversion treatment aluminum. It is obtained by extruding as a molten resin film having a thickness of 30 μm as a layer, extruding and laminating the laminated surface with aluminum of the molten resin film to form a laminate, and then heating it above the softening point of MDPE. The laminate was embossed using the laminate, and the lid was cut into a predetermined size without molding to obtain an exterior body.
5. As an adhesive film, with the tabs sandwiched by acid-modified LLDPE 100 μm, the battery body is housed in the embossed part of the exterior body, the lid is covered and the periphery is heat-sealed to form an embossed lithium ion battery. Obtained.

  Using the lithium ion batteries of the present invention obtained in Examples 1 to 4, when charging and discharging were repeated over a long period of time, none of the contents leaked, and the sealing performance in the outer package in the pinched portion of the tab Was good.

  The present invention seals a lithium ion battery main body by housing a lithium ion battery main body including a positive electrode and a negative electrode, and an electrolyte filled between the positive electrode and the negative electrode, and heat-sealing the peripheral portion. Metal lithium-ion battery tab used for a lithium-ion battery having an exterior body, connected to a positive electrode and a negative electrode, sandwiched by the exterior body so that the tip protrudes outside, and heat-sealing the sandwiched portion An insulating layer made of an insulating resin film is provided on at least the sandwiched portion of the tab, and a hydrogen fluoride-resistant chemical conversion treatment layer is provided so as to cover the entire sandwiched portion including the insulating layer.

  In the present invention, a heat-resistant polymer having a glass transition point of at least 200 ° C. and a coupling agent are dissolved or dispersed in a solvent on a part of the front and back surfaces and side surfaces of the tab material slit into the final use width of the metal sheet. Or a solution obtained by dissolving or dispersing a fluororesin formed from a fluorine-containing copolymer containing a hydroxyl group and a curing agent in a solvent, and applying the solution to the surface of the tab material, A lithium ion battery tab is manufactured by forming an insulating layer made of an insulating resin film by drying, and forming a hydrogen fluoride-resistant chemical conversion treatment layer so as to cover the entire sandwiched portion including the insulating layer.

  Thereby, in the aluminum tab where the corrosion of the tab due to the hydrofluoric acid generated by the reaction between the electrolyte and moisture is remarkable, the sandwiched portion is hardly corroded, and the sealing performance can be maintained for a long period of time. Therefore, a lithium ion battery tab that can be applied to a large-sized lithium ion battery that generates high voltage and has a long service life can be provided simply and at low cost.

  In addition, by using the lithium ion battery tab of the present invention, it is possible to provide a large-sized lithium ion battery with high durability and safety suitable as a power source for energy storage or electric vehicles.

These are the perspective view and exploded perspective view of the lithium ion battery (pouch type) of the present invention. These are the expanded sectional views which show the structure of the tab periphery of the lithium ion battery of this invention. These are the perspective view and exploded perspective view of the lithium ion battery (emboss type) of the present invention. FIG. 4 is a cross-sectional view (a) of a lithium ion battery tab of the present invention, a cross-sectional view (b) in a state in which a lithium ion battery main body is housed in an exterior body, and a cross-sectional view (c) after heat-sealing a tab clamping portion. It is. These are sectional drawings which show the laminated structure of the exterior body used for this invention. These are the perspective views explaining the mounting method of the adhesive film in the heat seal of a lithium ion battery tab and an exterior body. These are perspective views explaining the other mounting methods of an adhesive film.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Lithium ion battery 2 Lithium ion battery main body 3 Cell (electric storage part)
4 Tab 4a Tab material 4b Insulating layer 4c Chemical conversion treatment layer (tab)
4d opening 5 exterior body 6 adhesive film 7 sandwiching portion 8 positive electrode current collector 10 laminate 11 base material layer 12 barrier layer 13 intermediate layer 14 innermost layer (heat seal layer)
15 Chemical conversion layer (barrier layer surface)
16 Adhesive layer

Claims (9)

A lithium ion battery main body comprising a positive electrode comprising a positive electrode active material and a positive electrode current collector, a negative electrode comprising a negative electrode active material and a negative electrode current collector, and an electrolyte filled between the positive electrode and the negative electrode, and the lithium ion battery And an outer body that seals the main body of the lithium-ion battery by heat-sealing a peripheral portion thereof, and is connected to the positive electrode and the negative electrode, and has a tip that is externally connected by the outer body. It is a metal lithium ion battery tab that is sandwiched so as to protrude and is heat sealed.
An insulating layer made of an insulating resin film is provided on at least the sandwiched portion of the tab, and a hydrogen fluoride-resistant chemical conversion treatment layer is provided so as to cover the entire sandwiched portion including the insulating layer. Feature lithium-ion battery tab.   The lithium ion battery tab according to claim 1, wherein the insulating layer is a heat-resistant polymer having a glass transition point of at least 200 ° C. or more.   The lithium ion battery tab according to claim 2, wherein the heat-resistant polymer is a polyimide resin, a polyamideimide resin, a polyetherimide resin, or a mixture of two or more thereof.   The lithium ion battery tab according to claim 1, wherein the insulating layer is a fluorine-based resin formed from a fluorine-containing copolymer containing a hydroxyl group and a curing agent.   The lithium ion battery tab according to any one of claims 1 to 4, wherein the chemical conversion treatment layer is formed by a phosphoric acid chromate treatment.   The lithium ion battery provided with the lithium ion battery tab in any one of Claims 1 thru | or 5.   The lithium ion battery according to claim 6, wherein an adhesive film is interposed between the sandwiched portion and the exterior body. Slitting the metal sheet into the final use width to make the tab material,
A degreasing step of degreasing the front and back surfaces and side surfaces of the tab material;
On the surface of the tab material, a part of the front and back surfaces and side surfaces of the tab material is obtained by dissolving or dispersing a heat-resistant polymer having a glass transition point of at least 200 ° C. and a coupling agent in a solvent. An insulating layer forming step of forming an insulating layer made of an insulating resin film by applying and drying;
And a chemical conversion treatment step of forming a hydrogen fluoride-resistant chemical conversion treatment layer so as to cover at least the insulating layer. Slitting the metal sheet into the final use width to make the tab material,
A degreasing step of degreasing the front and back surfaces and side surfaces of the tab material;
The tab material is obtained by dissolving or dispersing a part of the front and back surfaces and side surfaces of the tab material in a solvent with a fluorine-containing copolymer containing a hydroxyl group and a curing agent. An insulating layer forming step of forming an insulating layer made of an insulating resin film by applying to the surface and drying;
And a chemical conversion treatment step of forming a hydrogen fluoride-resistant chemical conversion treatment layer so as to cover at least the insulating layer.

Images