JP2015176776A - Method for manufacturing lithium ion secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a lithium ion secondary battery which enables the simplification of a manufacturing process of a lithium ion secondary battery, and enables the release of hydrogen generated in a battery by a simple method.SOLUTION: A method for manufacturing a lithium ion secondary battery comprises the steps of: injecting an electrolyte into a battery container 101 through an electrolyte inlet 102 of the battery container; and thereafter sealing the electrolyte inlet 102 with a selectively hydrogen-permeable film 11. Especially, the selectively hydrogen-permeable film 11 serving to seal the electrolyte inlet 102 is arranged as an air permeable member 1 held by a frame 10. Further, the air permeable member 1 is integrally formed so that a protection sheet material 21 is disposed on each side of the selectively hydrogen-permeable film 11.

Description

  The present invention relates to a method for manufacturing a lithium ion secondary battery.

  Lithium ion secondary batteries are widely used as batteries for mobile phones, notebook computers, automobiles, and the like.

  In recent years, lithium-ion secondary batteries have become increasingly interested in safety in addition to increasing capacity and improving cycle characteristics. In particular, lithium ion secondary batteries are known to generate hydrogen in the cell, and there is concern about the expansion and rupture of the battery pack accompanying an increase in internal pressure. For this reason, the pressure inside a container is adjusted by discharging the hydrogen generated in the container to the outside (see Patent Document 1). However, in order to release the hydrogen generated inside, it is necessary to provide a discharge hole in the battery container, which makes the configuration complicated and the manufacturing process complicated.

  On the other hand, in a lithium ion secondary battery, after assembling an electrode, the electrode is accommodated in a battery container and a non-aqueous electrolyte is injected. The inlet into which the non-aqueous electrolyte is injected is sealed by laser welding, but problems such as welding defects and poor bonding may occur due to the influence of the electrolyte and solvent. Also, until the inlet is sealed, in order to reduce the invasion of water vapor as much as possible, it was necessary to work in a low-humidity environment, resulting in costs for dedicated equipment and air conditioning.

JP-A-11-250887

  The present invention has been made in view of the above-described problems, and is a method of manufacturing a lithium ion secondary battery that can simplify the manufacturing process of a lithium ion secondary battery and release hydrogen generated inside the battery by a simple method. The purpose is to provide.

  The present invention is a method for producing a lithium ion secondary battery, wherein after the electrolyte is injected from the electrolyte inlet of the battery container, the electrolyte inlet is sealed with a hydrogen selective permeable membrane, The present invention relates to a method for manufacturing a lithium ion secondary battery.

  In particular, the present invention relates to a method for manufacturing a lithium ion secondary battery, wherein the hydrogen selective permeable membrane that seals the electrolyte solution inlet is configured as a ventilation member held by a frame.

  In the ventilation member, it is preferable that the hydrogen selective permeable membrane and the protective membrane are integrally configured so that protective sheet materials are disposed on both sides of the hydrogen selective permeable membrane.

  According to the method for manufacturing a lithium ion secondary battery of the present invention, since the hydrogen selective permeable membrane is arranged using the electrolyte solution inlet, the sealing step of the electrolyte solution inlet can be simplified. Further, hydrogen generated inside can be discharged, and the battery life can be stabilized. Furthermore, since it can seal immediately after inject | pouring electrolyte solution, there is no invasion of water vapor | steam, and the operation | work in a low-humidity environment can be reduced.

It is the perspective view which shows the ventilation member of this embodiment, and the perspective view which shows the state which divided | segmented the ventilation member. It is a schematic sectional drawing which shows the battery container of this embodiment.

  Embodiments of the present invention will be described below.

  The manufacturing process of the lithium ion secondary battery includes a step (1) of forming an electrode body provided with a positive electrode, a negative electrode and a separator, a step (2) of assembling a battery by inserting the electrode body into a battery container, and electrolysis from an electrolyte inlet. It consists of a step (3) for injecting a solution, a step (4) for sealing the electrolyte injection port, and a step (5) for charging. In the present invention, in particular, in the step (4) of sealing the electrolyte inlet, the electrolyte inlet is sealed with a hydrogen selective permeable membrane.

  In step (1) of the method for producing a lithium ion secondary battery of the present invention, an electrode body including a positive electrode, a negative electrode, and a separator is formed. Although the method is not particularly limited, an electrode body having a flat winding structure is formed by pressurizing the positive electrode and the negative electrode so as to be flat after being wound in a spiral shape via a separator. In the present invention, the electrode body may not have a flat shape or a wound structure according to the shape of the battery.

  The negative electrode used in the present invention is not particularly limited, and conventionally known negative electrodes can be used. For example, a negative electrode mixture prepared by adding a binder or the like to the negative electrode active material is dispersed in a solvent and contains a negative electrode mixture. Prepare a paste, apply the obtained negative electrode mixture-containing paste to a negative electrode current collector made of copper foil, etc., dry it to form a negative electrode mixture layer, and pressurize the negative electrode mixture layer as necessary What was produced by passing through the process to shape | mold is mentioned.

  Examples of the negative electrode active material include carbon materials that can occlude and release lithium, such as graphite, pyrolytic carbons, cokes, glassy carbons, organic polymer compound fired bodies, mesocarbon microbeads, and carbon fibers. One kind or a mixture of two or more kinds is used.

  As a binder used for preparation of a negative electrode, a cellulose ether compound, a rubber-type binder, etc. are mentioned, for example. Specific examples of the cellulose ether compound include carboxymethyl cellulose, carboxyethyl cellulose, hydroxyethyl cellulose, alkali metal salts such as lithium salts, sodium salts, and potassium salts, ammonium salts, and the like. Specific examples of rubber binders include, for example, styrene / conjugated diene copolymers such as styrene / butadiene copolymer rubber, nitrile / conjugated diene copolymer rubbers such as nitrile / butadiene copolymer rubber (NBR), poly Silicone rubbers such as organosiloxane, polymers of alkyl acrylates, acrylic rubbers obtained by copolymerization of alkyl acrylates with ethylenically unsaturated carboxylic acids and / or other ethylenically unsaturated monomers, vinylidene fluoride Fluororubber such as ride copolymer rubber may be used.

  The positive electrode used in the present invention is not particularly limited, and conventionally known positive electrodes can be used. For example, a positive electrode mixture prepared by mixing a positive electrode active material with a conductive additive and a binder as necessary is mixed. Then, a paste containing a positive electrode mixture is prepared by dispersing in a solvent, and the obtained positive electrode mixture-containing paste is applied to a positive electrode current collector made of an aluminum foil or the like and dried to form a positive electrode mixture layer. Depending on, what is produced by going through the step of pressure-molding the positive electrode mixture layer can be mentioned.

The positive electrode active material is preferably a lithium-containing composite metal oxide from the viewpoint of being suitable for increasing the capacity. Examples of such lithium-containing composite metal oxides include lithium cobalt oxides such as LiCoO ₂ , lithium manganese oxides such as LiMnO ₂ and LiMn ₂ O ₄ , lithium nickel oxides such as LiNiO ₂ , LixMO ₂ (M Represents two or more elements of Ni, Mn, Co and Al, and a lithium-containing composite metal oxide represented by 0.9 <x <1.2) is preferably used.

  Examples of the conductive assistant used for the positive electrode include carbon black, ketjen black, acetylene black, and flaky graphite. And as a binder, the thing similar to what was illustrated above as a binder used for a negative electrode can be used.

  It does not specifically limit as a separator used by this invention, A conventionally well-known thing can be used, For example, a microporous resin film is used. Examples of the microporous resin film include a microporous polyethylene film, a microporous polypropylene film, a microporous ethylene-propylene copolymer film, a microporous polypropylene / polyethylene bilayer film, and a microporous polypropylene / polyethylene / polypropylene 3 Examples thereof include a layer film. The thickness of the separator is preferably 10 to 30 μm, for example, and the porosity is preferably 30 to 60%, for example.

  In step (2) of the method for producing a lithium ion secondary battery of the present invention, the electrode body is inserted into the battery container to assemble the battery. Although not described in detail, a process of connecting the positive and negative terminals and welding the lid of the battery container after inserting the electrode body into the battery container is also included.

  The battery container in the present invention constitutes a main part of the battery outer package, and this battery container also serves as a positive electrode terminal. Suitable materials for the battery container include, for example, iron (preferably having a surface plated with Ni or the like), stainless steel, aluminum, aluminum alloy, and the like.

  In step (3) of the method for producing a lithium ion secondary battery of the present invention, an electrolytic solution is injected from an electrolytic solution injection port provided in the lid portion of the battery container.

  The electrolytic solution in the present invention is not particularly limited, and conventionally known electrolytic solutions can be used, and those prepared by dissolving an electrolyte salt such as a lithium salt in an electrolytic solution solvent can be used.

  Examples of the electrolyte solvent include ethylene carbonate, propylene carbonate, dimethyl carbonate, methyl ethyl carbonate, tetrahydrofuran, γ-butyrolactone, 1,2-dimethoxyethane, and the like. These solvents can be used as one or a mixture of two or more.

As the electrolyte salt, _{e.g., LiPF 6, LiClO 4, LiBF} 4, LiAsF 6, LiSbF 6, LiCF 3 SO 3, LiC 4 F 9 SO 3, LiCF 3 CO 2, Li 2 C 2 F 4 (SO 3) 2 , LiN (CF ₃ SO ₂ ) ₂ , LiC (CF ₃ SO ₂ ) ₃ , LiC _n F _{2n + 1} SO ₃ (n ≧ 2) and the like may be used, and these may be used alone or in combination of two or more. May be used in combination. The electrolyte salt concentration in the electrolytic solution is preferably, for example, 0.6 to 1.6 mol / l.

  In addition to this, a well-known additive may be appropriately added to the electrolytic solution.

  The method for injecting the electrolytic solution is not particularly limited, and an appropriate amount is injected from the electrolytic solution injection port by a method in which the inside of the battery container is decompressed or a method using the pressure of hydrogen. The electrolyte solution can be injected once, but it may be divided into a plurality of times.

  In step (4) of the method for producing a lithium ion secondary battery of the present invention, the electrolyte inlet is sealed with a hydrogen selective permeable membrane. That is, a discharge function for discharging hydrogen generated inside is formed simultaneously with sealing the electrolyte injection port.

  The hydrogen permselective membrane used in the present invention is not particularly limited as long as it permeates hydrogen and blocks water and water vapor, and a conventionally known one can be used. For example, a resin such as aromatic polyimide can be used. And a sheet material including a layer made of a hydrogen permeable metal such as vanadium, vanadium alloy, palladium alloy, niobium, or niobium alloy.

  The hydrogen selective membrane can be used alone, but may be laminated with a support to ensure strength and improve handling. The support is not particularly limited as long as it is hydrogen permeable and can support the hydrogen selective permeable membrane, and may be a non-porous body or a porous body. The support may be a woven fabric or a non-woven fabric. Examples of the support forming material include polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate and polyethylene naphthalate, polyaryl ether sulfones such as polysulfone and polyethersulfone, fluorine such as polytetrafluoroethylene and polyvinylidene fluoride, and the like. Resins, epoxy resins, polyamides, polyimides and the like can be mentioned. Of these, polysulfone or polytetrafluoroethylene which is chemically and thermally stable is preferably used.

  Although the thickness of a support body is not specifically limited, Usually, about 5-1000 micrometers, Preferably it is 10-300 micrometers.

  In the present invention, the shape of the hydrogen selective permeable membrane may be substantially circular, or may be a polygon such as a triangle, a quadrangle, or a pentagon.

  Such a hydrogen permselective membrane may be used as it is as a sealing material for the electrolyte inlet, but from the viewpoint of process simplicity and ensuring the reliability of the sealing part, It is suitable that it is configured as a ventilation member held by a frame and is sealed by being loaded into the electrolyte solution inlet. Hereinafter, a ventilation member according to the present invention will be described with reference to the drawings.

  FIG. 1 is a perspective view of the ventilation member 1 and a perspective view in which the ventilation member is divided. The ventilation member 1 has a hydrogen selective permeable membrane 11 and a protective membrane 21 held inside by a frame body 10.

  The frame 10 is formed in a substantially cylindrical shape having both ends opened and the openings connected. The hydrogen selective permeable membrane 11 and the protective membrane 21 are accommodated on the inner peripheral surface of the opening of the frame body 10. The peripheral edge portions of the hydrogen selective permeable membrane 11 and the protective membrane 21 and the inner surface of the frame body 10 may be fixed by adhesion or welding. The frame 10 is provided with a ventilation path, and the hydrogen selective permeable membrane 11 and the protective film 21 are attached inside the frame so as to block the ventilation path.

  The material of the frame 10 is not particularly limited, and examples thereof include thermoplastic resins such as polybutylene terephthalate, acrylonitrile butadiene styrene resin, and thermoplastic elastomer. When a frame is formed from a thermoplastic resin, it is preferable because it can be easily formed into a desired shape.

  In the ventilation member 1 of the present embodiment, two protective films 21 having the same configuration are arranged on both sides of the hydrogen selective permeable film 11. The protective film 21 may be disposed only on one surface side of the hydrogen selective permeable film 11 or may be configured such that the protective film 21 is not provided. The protective film 21 is a sheet material that protects the hydrogen selective permeable membrane 11 by inhibiting the adhesion of moisture, organic matter, and other contaminants that inhibit hydrogen permeation to the surface of the hydrogen selective permeable membrane 11. is there. As a material of the protective film 21, an appropriate material can be selected according to the hydrogen selective permeable film 11 to be protected. For example, a porous film made of polytetrafluoroethylene (PTFE), ceramic, metal, resin, or the like. Etc. Among these, a porous film made of PTFE is preferable as a material for the protective film 21 because of its high water repellency and high heat resistance and chemical resistance.

  Next, a method for sealing the electrolyte solution inlet with the ventilation member of this embodiment will be described. FIG. 2 is a schematic cross-sectional view of the lithium ion secondary battery 100 of the present embodiment, and shows a state in which the electrolyte inlet 102 provided in the battery container 101 is sealed with the ventilation member 1. The ventilation member 1 is disposed in the electrolyte injection port 102 so as to block the ventilation path of the electrolyte injection port 102 with the hydrogen selective permeable membrane 11 and the protective film 21. In FIG. 2, other components such as electrodes of the battery case 101 are omitted.

  The method of attaching the ventilation member 1 to the electrolyte solution inlet 102 of the battery container 101 is not particularly limited, but is a method of fixing with an adhesive, a method of fixing via an EPDM or PTFE O-ring, and fixing by thermal fusion. And the like. As a result, the electrolyte injection port 102 can be reliably sealed, and stable power generation without performance deterioration can be performed.

  Further, in the present invention, when the internal pressure temporarily rises by adjusting the adhesive force between the ventilation member 1 and the battery container 101 so that the ventilation member 1 is dropped at a predetermined pressure, the ventilation member 1 is connected to the safety valve. It is also possible to use as.

  In the battery container 101 of the present embodiment, hydrogen passes through the one protective film 21, the hydrogen selective permeable film 11, and the other protective film 21 in this order in the ventilation path P of the electrolyte solution inlet 102.

  In step (5) of the method for producing a lithium ion secondary battery of the present invention, the produced lithium ion secondary battery is charged. The charging method, conditions, and the like are not particularly limited, and can be performed by a conventionally known method. For example, by a general constant current-constant voltage method, charging is performed at a constant current of 0.5 to 1 C to the charging end voltage (4.1 V), and charging is performed until the charging current value is reduced to about 0.01 C. After charging, aging may be performed as necessary.

  According to the method for manufacturing a lithium ion secondary battery of the present invention, since the hydrogen selective permeable membrane is arranged using the electrolyte solution inlet, the sealing step of the electrolyte solution inlet can be simplified. Further, hydrogen generated inside can be discharged, and the battery life can be stabilized.

1: Ventilating member 10: Frame 11: Hydrogen selective permeable membrane 21: Protective membrane 100: Lithium ion secondary battery 101: Battery container 102: Electrolyte injection port

Claims (3)

  A method for producing a lithium ion secondary battery, characterized in that after the electrolyte is injected from the electrolyte inlet of the battery container, the electrolyte inlet is sealed with a hydrogen selective permeable membrane. Battery manufacturing method.   2. The method for manufacturing a lithium ion secondary battery according to claim 1, wherein the hydrogen selective permeable membrane that seals the electrolyte solution inlet is configured as a ventilation member that is held by a frame. The hydrogen selective permeable membrane and the protective membrane are integrally configured so that protective sheet materials are disposed on both sides of the hydrogen selective permeable membrane in the ventilation member. The manufacturing method of the lithium ion secondary battery of description.

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