JP3791841B2 - Leakage inspection method for shape-variable packaging body, battery inspection method using the same, and battery manufacturing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a leakage inspection method for a shape-variable package, a battery inspection method using the same, and a battery manufacturing method.
[0002]
[Prior art]
A laminated film of a gas barrier layer made of a metal foil or the like and a resin layer made of a polymer film or the like (in this specification, such a resin layer may be simply referred to as a polymer film layer or a resin layer). Since it has flexibility and flexibility and is excellent in airtightness, it is suitably used as a shape-variable packaging body such as a vacuum packaging bag or a vacuum pack. In such a laminate film, the gas barrier layer made of a metal foil or the like prevents intrusion of gas from the outside and release of gas from the inside, and prevents deterioration of a substance accommodated in the inside. The resin layer made of a polymer film plays a role of maintaining mechanical strength and serving as an adhesive layer. In general, an aluminum foil is used for the gas barrier layer, and such a laminate film is called an aluminum laminated film.
[0003]
In recent years, a shape-variable package using such a laminate film has been used not only for food applications such as pasta sauce and soup, but also as a vacuum packaging bag for lithium secondary batteries. Such a lithium secondary battery has a form in which a battery element having a positive electrode, a negative electrode, and an electrolyte is enclosed in a shape-variable packaging body using the laminate film under reduced pressure. Originally, a lithium secondary battery has a high electromotive force (for example, 4 V), and further has a feature that a secondary battery having a high energy density can be obtained because the atomic weight of lithium is small. By enclosing such a lithium secondary battery in a bag for vacuum packaging, it is possible to reduce the weight of the product and further increase the energy density of the lithium secondary battery.
[0004]
Generally, a shape-variable package using a laminate film is formed by the following method. For example, a method of laminating two laminated films and bonding the surrounding resin layers by heat fusion (hereinafter, also referred to as “heat sealing” in the present specification), a substantially rectangular laminated film And then heat-sealing the overlapped part.
[0005]
[Problems to be solved by the invention]
However, the shape-variable packaging body as described above has a part where the resin layer of the laminate film is not sufficiently bonded (hereinafter referred to as “leak part” in the present specification) when heat sealing is incomplete. There is a risk that gas will be generated due to deterioration of contents and hydrolysis.
[0006]
Therefore, it is important to inspect the presence or absence of a minute leak portion at the time of manufacturing the product so that the form-variable packaging body incompletely joined as described above is not on the market. In particular, in a lithium secondary battery, a battery element sealed under reduced pressure in a shape-variable package is composed of a positive electrode, a negative electrode, and an electrolyte, and since this electrolyte contains a lithium salt that easily reacts with water, When moisture enters from the outside, battery performance is greatly reduced. Therefore, it is important to inspect the minute leak portion of the laminated film at the time of manufacturing the lithium secondary battery.
[0007]
By the way, as a method for inspecting the presence or absence of such a minute leak portion, for example, a dye coating method (specifically, an ageless seal check manufactured by Mitsubishi Gas Chemical Company, Inc.) is known. In this method, a deep wound agent with a pigment dispersed in a solvent is applied to the joint, and if there is a leak, the deep wound agent penetrates due to capillary action and is visually confirmed (ANELVA CORPORATION website). Http://www.anelva.co.jp/fuku/u/zemi/5322.htm).
[0008]
However, this dye application method cannot detect a leak portion smaller than the diameter of the pigment in the deep wound agent (for example, 10 μm or less), and can detect a minute leak portion corresponding to the size of a water molecule. There is a problem that cannot be done. Further, since the laminate film is provided with a gas barrier layer and a resin layer and is usually opaque, it is necessary to disassemble the laminate film in order to confirm the deep wound agent that has soaked into the leak portion. In other words, since the dye coating method is a destructive inspection, there is a problem that it cannot be applied to the total inspection of products.
[0009]
Further, as a leakage inspection for products that require airtightness, a bombing method using a helium gas leakage inspection method is known. In the bombing method, an object to be inspected that is once airtight like a semiconductor device is placed in a sealed box, and He gas is sealed in the sealed box, and He is infiltrated into the object under pressure from outside. Then, the inspection object is transferred to a vacuum container, and the leaked gas is inspected with a detector while evacuating the outside of the inspection object (M & E May 2002 issue May 2002 1). Published by Japan Industrial Research Council). Such a bombing method is not only a non-destructive test, but also uses He gas with a small molecular size, so that it is possible to detect a minute leak portion as small as water molecules, and the inspection sensitivity is very high.
[0010]
However, the bombing method requires a high vacuum inside the vacuum vessel to the extent that He gas leaks from the object to be inspected, and it is also necessary to provide an expensive vacuum exhaust device and gas detector. There is a problem that becomes high. In addition, since each inspection object is inspected one by one, there is also a problem that it is not suitable for 100% inspection of products. In other words, when the total inspection is performed by the bombing method, the inspection cost is significantly increased.
[0011]
The present invention is to solve the technical problem that has emerged when inspecting the presence or absence of a minute leak portion during product manufacture so that the form-variable packaging body incompletely joined as described above is not put on the market. Therefore, an object of the present invention is to provide an effective leak inspection method for quickly and inexpensively confirming whether or not there is a minute leak portion with respect to the total number of produced shape-variable packaging bodies.
Another object is to quickly determine the presence or absence of minute leaks in each shape-variable packaging for all batteries produced by enclosing the battery elements composed of positive electrode, negative electrode and electrolyte in the shape-variable packaging. Another object of the present invention is to provide an effective leakage inspection method that can be confirmed at low cost.
Another object of the present invention is to provide a battery manufacturing method in which the quality of the battery does not deteriorate after shipment and the stable quality is maintained.
[0012]
[Means for Solving the Problems]
Therefore, the present inventor has intensively studied to solve such a problem. A plurality of lithium secondary batteries in which battery elements are enclosed in an aluminum film are left in a chamber filled with 5 MPa helium for 1 hour, and then After returning to atmospheric pressure and leaving it in a reduced-pressure atmosphere of about 20 Pa and then removing it from the chamber, if the aluminum film has minute leaks or pinholes, the outer shape is bonded by expansion or heat sealing Since loosening or the like occurs in the formed part, it was found that if this was confirmed by visual inspection or palpation, an aluminum film with incomplete joining could be selected, and the present invention was completed based on such knowledge.
[0013]
Thus, according to the method for inspecting leakage of a shape-variable packaging body of the present invention, the shape-variable packaging body in which the package body is sealed under reduced pressure is held in a pressurized atmosphere of an inert gas, and the package body is sealed under reduced pressure. The shape-variable packaging body is held in a reduced-pressure atmosphere, and the shape-variable packaging body in which the packaged body is sealed under reduced pressure is returned to atmospheric pressure to check whether the shape-variable packaging body is deformed. .
[0014]
Specifically, the shape-variable packaging body used for sealing such a packaged body under reduced pressure is a vacuum packaging bag made of a laminate film in which a gas barrier layer and a polymer film layer are laminated. preferable.
[0015]
Next, the inert gas used in the leakage inspection method for the shape-variable package of the present invention has a molecular volume of 3.5 × 10. ^-2 nm ^Three The main component is the following molecule, and more specifically, as such an inert gas, a rare gas or a nitrogen gas is used. Of these, argon (Ar) and helium (He) are preferable. In the present invention, it is preferable to hold the shape-variable packaging body in which the packaged body is sealed under reduced pressure in an inert gas of 2 MPa or more and 15 MPa or less for a predetermined time. Then, it is preferable to keep in a reduced pressure atmosphere of 0.1 MPa or less for a short time.
[0016]
Furthermore, the present invention provides a battery element having a positive electrode, a negative electrode, and an electrolyte as a packaged body, and in the case of a battery in which the battery element is enclosed in a form-variable package under reduced pressure, this is a pressurized atmosphere of an inert gas. It can also be grasped as a method for inspecting a battery, characterized in that it is held inside, subsequently held in a reduced-pressure atmosphere, and finally returned to atmospheric pressure to confirm the presence or absence of deformation of the shape-variable packaging.
[0017]
The present invention includes a step of vacuum-sealing a battery element having a positive electrode, a negative electrode, and an electrolyte in a shape-variable packaging body, and the shape-variable packaging body in which the battery element is vacuum-sealed in an inert gas pressurized atmosphere. A step of holding the battery element in a reduced pressure atmosphere, a step of holding the battery element in a reduced-pressure atmosphere, and a shape variableity of the battery element in which the battery element is reduced in pressure by returning to atmospheric pressure. And a step of confirming whether or not the package body is deformed. The shape-variable packaging used is preferably a vacuum packaging bag made of a laminate film in which a gas barrier layer and a polymer film layer are laminated, and such a battery is a lithium secondary battery. Is preferred.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a leak inspection method for a shape-variable packaging body to which the present embodiment is applied, a battery leakage inspection method, and a battery manufacturing method will be described in detail.
First, in the leak inspection method for a shape-variable packaging body, the shape-variable packaging body in which the package body is sealed under reduced pressure is held in a pressurized atmosphere of an inert gas, and the shape in which the package body is sealed under reduced pressure. An operation for holding the variable packaging body in a reduced-pressure atmosphere, returning the shape-variable packaging body in which the package body is sealed under reduced pressure to atmospheric pressure, and then confirming whether the shape-variable packaging body is deformed or not. I do.
[0019]
This form-variable package means a package having flexibility, bendability, flexibility, and the like, and is made of a material that can seal the packaged body under reduced pressure. The package body is not particularly limited, and usually includes substances and products that need to avoid contact with oxygen, water, etc., and prevent deterioration of quality and performance for a long period of time. Applies to fields such as medical supplies and various industrial products.
[0020]
Specific examples of such a shape-variable package include aluminum, nickel-plated iron, a package made of metal such as copper, a vacuum packaging bag made of a polymer film, a gas barrier layer and a polymer film layer ( A vacuum packaging bag made of a laminate film laminated with a resin layer), a can made of plastic, a package body sandwiched between plastic plates and fixed by welding, bonding, fitting, or the like. Among these, a vacuum packaging bag made of a polymer film and a vacuum packaging bag made of a laminate film in which a gas barrier layer and a polymer film layer (resin layer) are laminated are particularly preferable in terms of airtightness and shape changeability. Most preferred is a vacuum packaging bag made of a laminate film in which a gas barrier layer and a polymer film layer (resin layer) are laminated. Such a laminate film has a high gas barrier property, a thin film thickness, and a high shape variability. As a result, it can be made thinner and lighter as a package, and used as a battery exterior material. The capacity of the entire battery can be improved.
[0021]
Such gas barrier layer materials include aluminum, iron, nickel-plated iron, copper, nickel, titanium, molybdenum, gold, and other metals; stainless steel, hastelloy, etc .; metal oxides, such as silicon oxide and aluminum oxide. Things can be used. Among these, aluminum that is lightweight and excellent in workability is preferable. Examples of the resin layer include various synthetic resins such as thermoplastics, thermoplastic elastomers, thermosetting resins, and plastic alloys. These resins can be mixed with fillers such as various fillers.
[0022]
FIGS. 1A to 1C are cross-sectional views for explaining an example of the configuration of such a laminate film. FIG. 1A shows a laminate film having a two-layer structure, in which a gas barrier layer 10 made of a metal foil or the like and a resin layer 11 made of a polymer film are laminated. FIG. 1B shows a laminate film having a three-layer structure, in which a gas barrier layer 10 made of metal foil or the like, and a first resin layer 12 and a second resin layer 13 made of a polymer film are laminated. Yes. The first resin layer 12 is provided on the outer surface of the gas barrier layer 10 and functions as an outer protective layer. The second resin layer 13 is provided on the inner surface of the gas barrier layer 10 and functions as an inner protective layer for preventing corrosion by the electrolyte and contact with the battery element. In this case, the resin used for the first resin layer 12 is preferably a resin excellent in chemical resistance and mechanical strength, such as polyethylene, polypropylene, modified polyolefin, ionomer, amorphous polyolefin, polyethylene terephthalate, and polyamide. Further, as the second resin layer 13, a synthetic resin having chemical resistance is used, and for example, polyethylene, polypropylene, modified polyolefin, ionomer, ethylene-vinyl acetate copolymer, or the like can be used.
[0023]
FIG. 1 (c) shows a laminated film having a multilayer structure, in which a gas barrier layer 10, a first resin layer 12, a second resin layer 13, and an adhesive layer 14 are laminated. The first resin layer 12 is provided on the outer surface of the gas barrier layer 10, the second resin layer 13 is provided on the inner surface of the gas barrier layer 10, and the adhesive layer 14 includes the gas barrier layer 10 and the first resin layer 12. And between the gas barrier layer 10 and the second resin layer 13. Examples of the material for the adhesive layer 14 include polyurethane-based two-component curable adhesives; polyolefin-based adhesives such as polyethylene-based, polypropylene-based, and modified polyolefin-based materials. Among them, polyurethane-based adhesives are preferable. .
[0024]
The laminated film as shown in FIGS. 1 (a), (b) and (c) is made of a resin such as polyethylene or polypropylene which can be welded to the innermost surface of the composite material in order to bond the exterior materials together. An adhesive layer can also be provided. The molding method of the shape-variable packaging body is not particularly limited, but is usually based on a method of fusing the periphery of the laminate film and a method of drawing a sheet-like body by vacuum molding, pressure molding, press molding, or the like. It can also be formed by injection molding a synthetic resin. When injection molding is used, the gas barrier layer is usually formed by sputtering or the like. In addition, in order to provide the accommodating part which consists of a recessed part in the exterior material used for a shape-variable packaging body, it can carry out by a drawing process etc. Moreover, it is preferable to use a film-like thing for the exterior material at the point which is easy to process.
[0025]
The thickness of such a laminate film is usually 0.01 μm or more, preferably 0.02 μm or more, more preferably 0.05 μm or more, and usually 1 mm or less, preferably 0.5 mm or less, more preferably 0.3 mm. Hereinafter, it is more preferably 0.2 mm or less, and most preferably 0.15 mm or less. The thinner the battery, the smaller and lighter the battery is. However, if the battery is too thin, not only will there be a greater risk of explosion due to an increase in the internal pressure of the package during high-temperature storage, but it will also not be possible to give sufficient rigidity or seal May be reduced.
[0026]
FIG. 2 is a diagram for explaining a shape-variable packaging body that accommodates a packaged body. The shape-variable packaging body shown here has an accommodating portion 20 and an exterior material 22 and encloses a package body 24. The accommodating part 20 forms a rectangular box-shaped recessed part, and the peripheral part 21 protrudes outward from each of the four peripheral parts in a flange shape. The exterior material 22 is a flat plate having a peripheral edge portion 23. After the packaged body 24 is accommodated in the accommodating part 20, the exterior material 22 is covered. Thereafter, the peripheral edge portion 21 of the housing portion 20 and the peripheral edge portion 23 of the outer packaging material 22 are hermetically bonded by a technique such as heat sealing (thermal sealing), thermocompression bonding, or ultrasonic welding in a reduced pressure (preferably vacuum) atmosphere. The package body 24 is enclosed.
[0027]
FIG. 3 is a view for explaining a shape-variable packaging body in which an exterior part and a housing part are a series. The shape-variable packaging body shown here has an accommodating portion 30, an exterior portion 32, and a peripheral portion 31, and a packaged body 34 is enclosed. The exterior part 32 is a flat plate. Further, the accommodating portion 30 forms a rectangular box-shaped concave portion, and a peripheral edge portion 31 projects outwardly from each of the three peripheral edges in a flange shape. After the packaged body 34 is accommodated in the accommodating part 30, the exterior part 32 is covered, and then the peripheral part 31 of the accommodating part 30 and the peripheral part 33 of the external part 32 are in a reduced pressure (preferably vacuum) atmosphere. The package body 34 is sealed by air-tight bonding by a technique such as heat fusion (heat sealing), thermocompression bonding, or ultrasonic welding.
[0028]
FIG. 4 is a view for explaining another embodiment of the shape-variable packaging body in which the exterior part and the housing part are a series. The shape-variable packaging body shown here has an accommodating portion 40, an exterior portion 42, and a peripheral portion 41, and a packaged body 44 is enclosed. The accommodating part 40 forms a rectangular box-shaped concave part, and the peripheral part 41 protrudes from the periphery. The exterior part 42 forms a rectangular box-like convex part, and the peripheral part 43 projects from the periphery. After the packaged body 44 is accommodated in the accommodating part 40, the exterior part 42 is covered, and then the peripheral part 41 of the accommodating part 40 and the peripheral part 43 of the exterior part 42 are in a reduced pressure (preferably vacuum) atmosphere. The packaged body 44 is sealed by airtight bonding by a technique such as heat sealing (heat sealing), thermocompression bonding, or ultrasonic welding. In addition, the exterior part 42 and the accommodating part 40 may be separate bodies.
[0029]
FIG. 5 is a diagram for explaining a shape-variable packaging body in which two laminated films are bonded and molded. The shape-variable packaging body shown here is composed of two laminated films 50 and 51, and a body to be packaged 54 is enclosed. Each of these three laminated films 50 and 51 is preliminarily bonded to each other by a method such as heat fusion (heat sealing), thermocompression bonding, ultrasonic welding, and the like, and a housing portion 53 is formed therein. It has a bag-like structure. After the packaged body 54 is housed in the housing part 53, the unbonded peripheral parts are hermetically joined by a technique such as thermocompression bonding or ultrasonic welding in a reduced pressure (preferably vacuum) atmosphere, A body 54 is enclosed.
[0030]
Next, an operation for holding the form-variable packaging body in which such a packaged body is sealed under reduced pressure in an inert gas pressurized atmosphere will be described. The inert gas used in the present embodiment means a gas that is chemically inert, and is a gas that does not react with the material of the packaged body enclosed under reduced pressure in the shape-variable packaging body. Examples include noble gases such as helium, neon, and argon, and nitrogen gas. Carbon dioxide can also be used in a dry state.
[0031]
As such an inert gas, for example, the molecular volume is 3.5 × 10 5. ^-2 nm ^Three An inert gas mainly composed of the following molecules can be used. By using a molecular gas having such a molecular volume, it is possible to detect a minute leak portion as large as a water molecule.
[0032]
The molecular volume was calculated by the following method. That is, the atomic volume of each atom constituting the molecule is obtained, and the total value of the volumes is defined as the molecular volume. The atomic volume of each atom was determined using the van der Waals radius of each atom. The molecular volume is 3.5 × 10 ^-2 nm ^Three The gas composed of the following molecules is preferably at least one selected from the group consisting of nitrogen, argon, and helium, for example. Since the van der Waals radius of nitrogen is 0.155 nm, the molecular volume of nitrogen is 3.12 × 10 ^-2 nm ^Three (= 4/3 × π × (0.155) ^Three × 2). Since the van der Waals radius of argon is 0.188 nm, the molecular volume of argon is 2.78 × 10 ^-2 nm ^Three (= 4/3 × π × (0.188) ^Three ) Since the van der Waals radius of helium is 0.14 nm, the molecular volume of helium is 1.15 × 10 10. ^-2 nm ^Three (= 4/3 × π × (0.14) ^Three )
[0033]
In the present embodiment, helium is preferably used as the inert gas. Since helium has a smaller molecular volume than water molecules and has the smallest molecular volume among inert gases, a minute leak portion can be detected with high sensitivity. Here, the volume of water molecules can be calculated from (volume of hydrogen atoms) × 2 + (volume of oxygen atoms). Since the van der Waals radius of hydrogen atoms is 0.12 nm, the volume of water atoms is 0. .723 × 10 ^-2 nm ^Three (= 4/3 × π × (0.12) ^Three Since the van der Waals radius of oxygen atoms is 0.152 nm, the volume of oxygen atoms is 1.471 × 10 ^-2 nm ^Three (= 4/3 × π × (0.152) ^Three ) The molecular volume of the water molecule is 2.92 × 10 ^-2 nm ^Three (= 2 × 0.723 × 10 ^-2 + 1.471 × 10 ^-2 ) The van der Waals radius may be the value shown in the literature such as the Chemical Handbook Basic Revised 4th Edition (published on September 30, 1993, published by the Chemical Society of Japan, Maruzen Co., Ltd.).
[0034]
In addition, the volume of the molecule | numerator of the inert gas to be used is the volume of a water molecule (2.92x10. ^-2 nm ^Three ) Is slightly larger than 3.5 × 10 ^-2 nm ^Three The following is preferable. This is because water molecules undergo Brownian vibration at normal temperature and humidity, and taking this vibration into account, it is necessary to perform measurement using molecules having a volume slightly larger than the volume of the water molecules themselves. Of course, the volume of water molecules (2.92 × 10 ^-2 nm ^Three ) It is preferable to use the following molecules because measurement with higher sensitivity is possible. Here, normal temperature and normal humidity refers to an environment of 25 ± 5 ° C./50±10% RH.
[0035]
In the present embodiment, the inert gas such as a rare gas such as helium and argon and the nitrogen gas is usually 50% by volume or more, preferably 70% by volume or more, more preferably in the total gas constituting the pressurized atmosphere. Is 80% by volume or more, more preferably 90% by volume or more, particularly preferably 99% by volume or more, and most preferably 99.99% by volume or more. If it is in said range, the commercially available inert gas can be used. For example, if helium gas is used, the commercially available helium cylinder has an industrial helium purity of 99.99%, a high purity of 99.999%, and an ultrahigh purity of 99.9999%. . Further, when the recovered helium is used for inspection in order to reuse the helium gas, a gas cylinder having a helium purity of about 98% is used. In addition, when the inert gas is poured into the cuvette and the atmosphere in the cuvette is changed to a pressurized atmosphere, the air remaining in the cuvette is removed in advance by a vacuum exhaust device or the like, and then the inert gas is inspected. When pouring into the container, the content of the inert gas in the total gas constituting the pressurized atmosphere can be increased. On the other hand, in order to simplify the apparatus, when an evacuation apparatus is not provided in the cuvette, an inert gas is further poured into the cuvette in the state where air remains in the cuvette. Even in this case, if the content of the inert gas in the total gas constituting the pressurized atmosphere is within the above range, the inert atmosphere can be sufficiently pressurized and infiltrated into the shape-variable packaging body. Become.
[0036]
Next, in the present embodiment, the pressure of the inert gas in the case where the variable shape packaging body in which such a packaged body is sealed under reduced pressure is held in a pressurized atmosphere of the inert gas is usually 0. On the other hand, it is usually 15 MPa or less, preferably 5 MPa or less, more preferably 1 MPa or less. The higher the pressure of the inert gas, the shorter the inspection time because the inert gas molecules are easier to penetrate under pressure when there are minute leaks in the shape-variable packaging. There is an advantage that the cost can be suppressed. On the other hand, when the pressure of the inert gas is increased, it is necessary to increase the pressure resistance of the cuvette that encloses the pressurized atmosphere, so that the cost of the pressure vessel used for the inspection increases. Therefore, if the pressure range is within the above range, the inspection cost and the pressure vessel cost can be well balanced.
[0037]
In the present embodiment, the time for holding the shape-variable packaging body in which the packaged body is sealed under reduced pressure in a pressurized atmosphere of inert gas is not particularly limited, but is usually 1 minute or more, preferably 10 minutes or more, More preferably, it is 30 minutes or more, while it is usually 5 hours or less, preferably 2 hours or less, more preferably 1 hour or less. In order to shorten the inspection time, it is necessary to shorten the holding time. For this purpose, it is necessary to increase the pressure of the inert gas, and thus it is necessary to make the pressure vessel expensive. On the other hand, if the holding time is lengthened, the pressure of the inert gas can be reduced, so that an inexpensive pressure vessel can be used. However, if the holding time is too long, the inspection time becomes longer, so the inspection cost becomes longer. Rises. Therefore, when the holding time is within the above range, the balance between the pressure vessel cost and the inspection cost can be well balanced.
[0038]
Subsequently, an operation for holding the form-variable packaging body in which such a packaged body is sealed under reduced pressure in a reduced-pressure atmosphere will be described. By performing this operation, if there is a minute leak portion in the shape-variable package, the inert gas that has entered from such a minute leak portion causes the shape-variable package to expand, Since the existing joint portion is loosened, the presence or absence of the leak portion can be easily confirmed.
[0039]
In this embodiment, the pressure in the reduced-pressure atmosphere is not particularly limited, but is usually 1 Pa or more and atmospheric pressure or less, specifically 0.1 MPa or less, preferably 50 Pa or less, more preferably 30 Pa or less. . In this embodiment, since the presence or absence of expansion of the shape-variable package or looseness of the joining portion can be easily confirmed, there is no need to reduce the pressure in the reduced-pressure atmosphere so much (high vacuum), and a rotary pump or the like It is sufficient to make the atmosphere in the above pressure range by using an inexpensive apparatus.
[0040]
In addition, the time for holding in the reduced-pressure atmosphere is sufficient as long as the shape-variable packaging body expands or the joined portion is loosened, and is sufficient to reduce the pressure in the atmosphere. It is enough. Although it does not specifically limit as time to hold | maintain, Specifically, it is 1 minute or more normally. On the other hand, it is usually 1 hour or less, preferably 30 minutes or less, more preferably 20 minutes or less.
[0041]
In addition, when trying to inspect the minute leak portion of the shape-variable packaging body in which the package body is sealed under reduced pressure, using a bombing method utilizing a conventionally known helium type gas leakage inspection method, It is necessary to extract the inert gas that has once entered the shape-variable package from the shape-variable package. For this reason, in the bombing method, it is necessary to increase the degree of vacuum in order to extract the inert gas (for example, 10 ^-7 About Pa). Furthermore, it is necessary to sufficiently extract the inert gas from the shape-variable packaging body by sufficiently increasing the holding time in a reduced-pressure atmosphere. The reason why it is necessary to take a high vacuum and a long holding time as described above in the bombing method is that the bombing method is an inspection method used for inspecting a device having a hard exterior such as a semiconductor device. Since the hardness of the exterior of the semiconductor device is high, the shape of the device does not change even when an inert gas enters the device. Therefore, it is necessary to extract the detected gas again and detect it.
[0042]
On the other hand, in the inspection method described in the present embodiment, a minute leak portion existing in the shape-variable packaging body is inflated by an inert gas that has entered the inside of the packaging body. Or by loosening the joint. For this reason, not only the degree of vacuum of the reduced pressure atmosphere is low, but also the holding time in the reduced pressure atmosphere is short. In addition, since the presence or absence of a minute leak portion is obvious at a glance if the swelling of the shape-variable package or the looseness of the case joint is inspected, it is not necessary to provide a gas detector in the inspection apparatus unlike the bombing method.
[0043]
Furthermore, in the case of the bombing method, if a gas is detected at once for a plurality of shape-variable packaging bodies, it is not possible to specify which inert gas is extracted from which sample, so only one sample can be inspected. There's a problem. On the other hand, in this embodiment, since it is not necessary to detect the inert gas extracted from the shape-variable packaging body, there is an advantage that a large amount of shape-variable packaging body can be inspected for the presence or absence of a minute leak portion at a time. .
[0044]
Next, after holding in a pressurized atmosphere of inert gas in this way, after performing an operation of holding in a reduced pressure atmosphere, confirm whether there is any deformation of the deformable packaging body in which the packaged body is sealed under reduced pressure How to do will be described.
[0045]
Specifically, for example, the shape-variable packaging body in which the package body is sealed under reduced pressure is taken out from the reduced-pressure atmosphere and returned to atmospheric pressure, and the presence or absence of swelling of the shape-variable packaging body or peeling of the joint portion is visually confirmed. The presence or absence of deformation of the shape-variable packaging body is confirmed by a method or a method of confirming whether or not the joint portion of the shape-variable packaging body is loose by touching (palpation) by hand. The looseness of the joint part of the shape-variable package means that the part is leaking.
[0046]
In the above-described bombing method, it is necessary to confirm the presence or absence of a minute leak portion in a high-vacuum reduced-pressure atmosphere using a gas detector. In the method described in this embodiment, such a complicated method is required. There is an advantage that it is not necessary to perform an operation, and after taking out the shape-variable packaging body under atmospheric pressure, it is possible to confirm the presence or absence of micro leaks by visual inspection or palpation.
[0047]
Next, a battery inspection method will be described. In the shape variable packaging body leakage inspection method described as the present embodiment as described above, the packaged body is a battery in which a battery element having a positive electrode, a negative electrode, and an electrolyte is enclosed in a shape variable packaging body under reduced pressure. Is characterized in that it is held in a pressurized atmosphere of an inert gas, subsequently held in a reduced-pressure atmosphere, and finally returned to atmospheric pressure to check for deformation of the shape-variable packaging. It can be understood as a battery inspection method. That is, the above-described minute leak portion is inspected as a battery inspection method using a shape-variable packaging body formed by bonding a laminate film formed by providing a gas barrier layer and a resin layer as a battery exterior material. It is preferable to use the method. This is because, in a battery using a shape-variable packaging body, if there is a leak portion at the joint portion of the shape-variable packaging body, moisture will enter the packaging body, and the performance deterioration of the battery element stored inside the packaging body The risk of gas generation due to electrolyte hydrolysis is particularly great. Therefore, the leak inspection method for the shape-variable packaging body described above is extremely effective as an inspection method for quickly confirming the presence or absence of a minute leak portion of the battery.
[0048]
With such a battery inspection method, the number of batteries that can be processed in a single inspection is necessary to maintain the capacity of the container used for maintaining the inert gas in a pressurized atmosphere and the reduced pressure atmosphere. It is appropriately selected according to the capacity of the container and the number of facilities, and is not particularly limited. For example, when one container having an internal capacity of 30 liters is used, it is usually possible to inspect 600 batteries at a time.
[0049]
Next, a specific example of this battery inspection method will be described based on the embodiment shown in FIGS. FIGS. 6A and 6B are diagrams for explaining the operation of the battery inspection method. As shown in FIG. 6 (a), the battery in which the battery element is sealed in a form-variable packaging body under reduced pressure is housed in a test case 60. And kept in a pressurized atmosphere of an inert gas fed into the chamber for a certain period of time. The inspection case 60 is divided into, for example, 4 to 6 vertical x 4 to 6 horizontal cells, and about 5 to 15 batteries are normally stored vertically in each cell. Subsequently, as shown in FIG. 6B, the inspection case 60 containing the battery is once taken out from the pressurization vessel 61 and returned to the atmospheric pressure, and then the rotary pump 64 is turned on in the decompression vessel 63. And kept in a reduced pressure atmosphere for a certain period of time. Thereafter, the battery is returned to atmospheric pressure again, and the presence or absence of deformation of the shape-variable package is confirmed.
[0050]
FIG. 7 is a view for explaining the inspection case 60. The inspection case 60 shown here has a total of 30 cells, 6 × 5 in width, and 10 batteries are stored in each cell, and 300 batteries are stored in the entire inspection case 60. ing. In the present embodiment, a total of 600 batteries respectively housed in two inspection cases 60 of the same size are held in a pressurized atmosphere of inert gas for a certain period of time in the pressurized container 61. The
[0051]
The shape variable packaging body and the inert gas used in the present embodiment can be the same as those described above. In addition, the conditions of the pressurized atmosphere of the inert gas and the conditions of the reduced pressure atmosphere are the same as those described above.
[0052]
Next, a battery manufacturing method will be described. In the battery manufacturing method, a battery element having a positive electrode, a negative electrode, and an electrolyte is sealed under reduced pressure in a shape-variable packaging body, and the shape-variable packaging body in which the battery element is sealed under reduced pressure is pressurized with an inert gas. The step of holding the inside, the step of holding the variable shape packaging body in which the battery element is enclosed in a reduced pressure atmosphere, the returning of the shape variable packaging body in which the battery element is enclosed under reduced pressure to atmospheric pressure, and the like. A step of confirming the presence or absence of deformation of the shape-variable packaging body that has been subjected to various operations.
[0053]
The shape-variable package used is preferably a vacuum packaging bag made of a laminate film in which a gas barrier layer and a polymer film layer are laminated. Examples of the battery include, but are not limited to, a manganese battery, a lithium secondary battery, a nickel hydrogen battery, a nickel cadmium battery, a nickel zinc battery, a sodium sulfur battery, a zinc halogen battery, and a redox flow battery. When the present invention is applied as a method for manufacturing a secondary battery, the effects of the present invention are remarkably exhibited.
[0054]
This is because a lithium secondary battery often uses a shape-variable package formed by bonding a laminate film in which a metal foil and a polymer film are laminated in order to reduce the weight of the battery. Further, in the lithium secondary battery, if there is a minute leak portion in the shape-variable packaging body, when charging / discharging is repeated, moisture enters the battery element from there, and therefore LiPF contained in the electrolyte. ₆ Lithium salts such as these are liable to decompose and react with water and generate gas. For this reason, in a lithium secondary battery, the necessity to use the shape-variable package which does not have a micro leak part is high.
[0055]
Below, based on the embodiment which made the lithium secondary battery an example, invention of the manufacturing method of this battery is explained. A lithium secondary battery usually has a battery element having a positive electrode, a negative electrode, an electrolyte containing a non-aqueous solvent and a solute, and a shape-variable package that houses the battery element.
[0056]
The positive electrode of the lithium secondary battery is usually a structure in which a positive electrode material layer is formed on a plate-shaped or mesh-shaped aluminum current collector having a thickness of 1 to 50 μm. In the positive electrode material layer, Contains a positive electrode active material capable of occluding and releasing Li. As the positive electrode active material, it is preferable to contain a lithium transition metal composite oxide such as a lithium-cobalt composite oxide, a lithium-manganese composite oxide, or a lithium-nickel composite oxide. In addition, the negative electrode usually has a negative electrode material layer containing a negative electrode active material formed on a plate-shaped or mesh-shaped copper current collector having a thickness of 1 to 50 μm. As the negative electrode active material, for example, a carbon-based active material such as graphite is used. Such a positive electrode material layer and a negative electrode material layer preferably contain a fluorine-based resin such as polyvinyl fluoride as a binder. Furthermore, you may contain additives, such as a conductive material and a reinforcing material, powder, a filler, etc. as needed.
[0057]
The method for producing the positive electrode or the negative electrode is not particularly limited. For example, a positive electrode or negative electrode production paint containing N-methylpyrrolidone or the like containing an active material, a binder, a conductive material, or the like is applied to a current collector and dried. Can be manufactured. Alternatively, the active material, binder, conductive material, and the like can be kneaded and then bonded to the current collector without using a solvent.
[0058]
The electrolyte used for the lithium secondary battery contains a nonaqueous electrolytic solution having a nonaqueous solvent and a solute. Examples of the non-aqueous solvent include cyclic carbonates such as ethylene carbonate; non-cyclic carbonates such as dimethyl carbonate; and high-boiling solvents selected from lactones such as γ-butyl lactone. Is preferred. As the solute, LiClO _Four , LiPF ₆ Conventionally known lithium salts such as these can be used, and these are usually contained in an amount of 0.5 to 2.5 mol / l with respect to the non-aqueous electrolyte.
[0059]
From the viewpoint of ensuring electrolyte retention and preventing leakage of electrolytes, the electrolyte is an acrylic polymer such as polymethyl methacrylate, an alkylene oxide polymer having an alkylene oxide unit, polyvinylidene fluoride, or vinylidene fluoride. It is preferable to contain a polymer such as a fluoropolymer such as a xafluoropropylene copolymer. Among them, an acrylic polymer obtained by polymerizing a monomer having an acryloyl group is preferable.
[0060]
Examples of monomers having an acryloyl group include alkyl monoacrylates such as methyl acrylate and ethyl acrylate; diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, propylene glycol diacrylate, dipropylene glycol diacrylate, and tripropylene. Polyalkylene glycol diacrylates such as glycol diacrylate and tetrapropylene glycol diacrylate; polyalkylene oxide triacrylates such as polyethylene oxide triacrylate are particularly preferred.
[0061]
It is also possible to improve the strength and liquid retention of the electrolyte by copolymerizing a monomer having an acryloyl group with other monomers such as methacrylamide, butadiene, acrylonitrile, styrene, vinyl acetate, vinyl chloride. The abundance ratio of the monomer having an acryloyl group with respect to all monomers is not particularly limited, but is usually 50% by weight or more, preferably 70% by weight or more, and particularly preferably 80% by weight or more.
[0062]
The acrylic polymer preferably forms a crosslinkable polymer by copolymerizing a polyfunctional monomer having a plurality of acryloyl groups with a monofunctional monomer having one acryloyl group, if necessary. When a polyfunctional monomer and a monofunctional monomer are used in combination, the equivalent ratio of the functional groups of the polyfunctional monomer is usually 10% or more, preferably 15% or more, and more preferably 20% or more.
[0063]
As a method for polymerizing these monomers, for example, a method of polymerizing with heat, ultraviolet rays, electron beams or the like can be used. For ease of production, it is preferable to polymerize the monomer by heating or ultraviolet irradiation. In the case of polymerization by heat, a polymerization initiator can be used. Examples of the polymerization initiator include azo compounds such as azobisisobutyronitrile, dimethyl 2,2′-azobisinbutyrate, benzoyl peroxide, cumene hydroperoxide, t-butylperoxy-2-ethylhexanoate, and the like. A peroxide etc. are mentioned.
[0064]
In addition, a polymerizable monomer of a polymer formed by polycondensation or polyaddition such as polyester, polyamide, polycarbonate, polyimide, polyurethane, polyurea, or the like can also be used.
[0065]
The content of the polymer contained in the electrolyte is usually 80% by weight or less, usually 0.1% by weight or more, based on the total weight of the electrolyte. The ratio of the polymer to the non-aqueous solvent is usually 0.1% by weight or more and usually 50% by weight or less.
[0066]
In this embodiment, a method is used in which a polymer is formed by filling a space (to be described later) in a spacer (which will be described later) and then polymerizing the monomer in a state in which the electrolyte contains a monomer that is a raw material for the polymer. Is preferred.
[0067]
In a lithium secondary battery, a spacer made of a porous film is usually used to prevent a short circuit between the positive electrode and the negative electrode. The spacer material is preferably a polyolefin such as polyethylene or polypropylene; or a fluorinated polymer such as polyvinylidene fluoride or polytetrafluoroethylene. The number average molecular weight of these polymers is usually 10,000 or more and usually 10 million or less.
[0068]
Examples of the porous membrane include a porous stretched membrane and a nonwoven fabric, and a stretched membrane produced by biaxial stretching is more preferable. The porosity of the spacer is usually 30% or more and usually 80% or less. The average pore diameter of the holes present in the spacer is usually 0.2 μm or less, and usually 0.01 μm or more. The film thickness of the spacer is usually 5 μm or more and usually 50 μm or less.
[0069]
The spacer usually has a withstand voltage of 0.3 kV or more and usually 1000 kV or less. In order to prevent a short circuit more effectively, the pin penetration strength when the spacer is locally pressed is usually 200 gf or more and usually 2000 gf or less. It is preferable to use a spacer whose strain generated when the spacer is pulled in a fixed direction with a force of 0.1 kg / cm is 1% or less, usually 0.01% or more.
[0070]
The thermal contraction rate of the spacer at 100 ° C. is usually 10% or less with respect to one direction. The surface tension of the spacer is usually 40 dyne / cm or more and usually 60 dyne / cm or less.
[0071]
As a form of the battery element of the lithium secondary battery, for example, a flat plate laminated type in which a plurality of unit battery elements having a flat positive electrode, a flat negative electrode, and an electrolyte are stacked, and the unit battery element formed in a long shape is used. Examples of the plate-shaped winding type wound in a flat plate shape, and further, a cylindrical winding type obtained by winding a long unit battery element into a cylindrical shape. It is preferable that it is a type | mold or a flat laminated type. When the battery element takes the form of a flat wound type, the number of windings of the unit battery element is usually 2 or more and usually 20 or less. Further, when the battery element takes the form of a flat plate type, the number of unit battery elements stacked is usually 5 layers or more and usually 50 layers or less.
[0072]
Hereinafter, a description will be given based on a lithium secondary battery in which flat plate type battery elements are sealed in a shape variable packaging body under reduced pressure.
FIG. 8 is a diagram for explaining the first embodiment of the lithium secondary battery. The lithium secondary battery shown here is one in which a battery element 84 is enclosed in a shape-variable package. The shape-variable packaging body has an accommodating portion 80, an exterior material 82, and a peripheral portion 81. The accommodating portion 80 forms a rectangular box-shaped concave portion, and the peripheral portion 81 is outwardly formed in a flange shape from the four peripheral portions. Overhangs. The exterior material 82 is a flat plate having a peripheral edge portion 83. The battery element 84 has a pair of leads 85 a and 85 b, and the pair of leads 85 a and 85 b extends from the end of the battery element 84. An insulating material 86 is injected near the end of the battery element 84. After the battery element 84 is accommodated in the accommodating portion 80, the exterior material 82 is covered, and then the peripheral portion 81 of the accommodating portion 80 and the peripheral portion 83 of the external material 82 are heated in a reduced pressure (preferably vacuum) atmosphere. The battery element 84 is sealed by airtight bonding by a technique such as fusion (heat sealing), thermocompression bonding, or ultrasonic welding.
[0073]
FIG. 9 is a cross-sectional view of the lithium secondary battery shown in FIG. The battery element 84 shown here has a plurality of unit battery elements stacked in the thickness direction, tabs 90a and 90b drawn out from the unit battery element, an insulating material 86, and a pair of leads made of flaky metal. 85a, 85b. By connecting the tabs 90a and 90b and the leads 85a and 85b, the leads 85a and 85b and the positive electrode and the negative electrode of the battery element 84 are electrically connected. Insulating material 86 is injected in the vicinity of tabs 90a, 90b. The pair of leads 85 a and 85 b extending from the battery element 84 are drawn out through the mating surfaces of the peripheral edge portion 83 of the exterior material 82 and the peripheral edge portions 81 of the housing portion 80, respectively. The tabs 90a, the tabs 90b, and the tabs 90a, 90b and the leads 85a, 85b can be joined by resistance welding such as spot welding, ultrasonic welding, or laser welding.
[0074]
As described in FIG. 8, the battery element 84 is accommodated in the accommodating portion 80 of the shape-variable packaging body, and the insulating material 86 is injected in the vicinity of the tabs 90 a and 90 b, and the battery elements in the vicinity of the positive electrode terminal portion and the negative electrode terminal portion. After the side surfaces are covered with the insulating material 86, the exterior material 82 is covered. Thereafter, the peripheral edge portion 81 of the accommodating portion 80 and the peripheral edge portion 83 of the exterior member 82 are hermetically bonded by a technique such as heat sealing (thermal sealing), thermocompression bonding, or ultrasonic welding in a reduced pressure (preferably vacuum) atmosphere. The battery element 84 is enclosed in the shape-variable packaging. Thereafter, the insulating material 86 is subjected to a curing process by heating or the like, and the insulating material 86 is completely fixed in the vicinity of the terminal portion.
[0075]
As the insulating material 86 injected into the vicinity of the terminal portion of the battery element 84 used in the lithium secondary battery shown in FIGS. 8 and 9, an epoxy resin, an acrylic resin, a silicone resin, etc. are exemplified. Among them, an epoxy resin or an acrylic resin is preferable because of a short curing time. In particular, an acrylic resin is most preferable because it may be shared with an electrolyte material and has a low possibility of adversely affecting battery performance. The insulating material 86 is supplied to the vicinity of the terminal portion in an uncured and fluid state, and is completely fixed in the vicinity of the terminal portion by curing. The insulating material 86 is a battery extending from the positive electrode terminal portion to the negative electrode terminal portion in order to enhance the bonding between the peripheral edge portion 81 of the housing portion 80 and the peripheral edge portion 83 of the exterior material 82 and to enhance safety during high temperature storage. The entire side of the element 84 can be covered. The insulating material 86 is a method of injecting the insulating material 86 in the vicinity of the terminal portion after the battery element 84 is accommodated in the accommodating portion, or the battery element 84 after the insulating material 86 is supplied in the vicinity of the terminal portion of the battery element 84. Any method of accommodating in the accommodating portion can be adopted as appropriate.
[0076]
Further, it is preferable to use an annealed metal as at least one of the pair of positive and negative leads 85a and 85b, preferably both. As a result, a battery excellent in not only strength but also bending durability can be obtained. Generally, aluminum, copper, nickel, SUS, or the like can be used as the type of metal used for the leads 85a and 85b. A preferred material for the positive electrode lead is aluminum. A preferred material for the negative electrode lead is copper. The thickness of the leads 85a and 85b is usually 1 μm or more, preferably 10 μm or more, more preferably 20 μm or more, and most preferably 40 μm or more. If it is too thin, the mechanical strength of the lead such as tensile strength tends to be insufficient. The thickness of the leads 85a and 85b is usually 1000 μm or less, preferably 500 μm or less, and more preferably 100 μm or less. If it is too thick, the bending durability tends to deteriorate, and sealing of the battery element 84 by the case tends to be difficult. The advantage of using an annealed metal for the leads 85a and 85b becomes more conspicuous as the leads 85a and 85b are thicker. The widths of the leads 85a and 85b are usually 1 mm or more and 20 mm or less, particularly about 1 mm or more and 10 mm or less, and the exposed length of the leads 85a and 85b is usually about 1 mm or more and 50 mm or less.
[0077]
FIG. 10 is a diagram for explaining a battery element 84 used in the lithium secondary battery shown in FIG. In the battery element 84 shown here, a plurality of unit battery elements are stacked in the thickness direction, and tabs 90a and 90b are drawn out from these unit battery elements. The tabs 90a and 90b from the positive electrode are overlapped with each other. The tab 90a is joined to a positive lead 85b (not shown) to form a positive terminal portion. The tabs 90b from the negative electrode are also bundled, and a negative electrode lead 85b (not shown) is joined to form a negative electrode terminal portion.
[0078]
FIG. 11 is a view for explaining a state in which the battery element in the lithium secondary battery shown in FIG. The lithium secondary battery shown here has an accommodating portion 80, a peripheral edge portion 81 (83), and a pair of leads 85a and 85b, and a battery element 84 is enclosed. The peripheral edge portion 81 (83) protrudes outward from the housing portion 80 in advance, is bent along the housing portion 80, and is further side-faced with an adhesive, an adhesive tape (not shown), or the like. Fasten to (fixed).
[0079]
FIG. 12 is a diagram for explaining a second embodiment of a lithium secondary battery. In the lithium secondary battery shown here, the battery element 124 is enclosed in a shape-variable package. This shape-variable package has a housing part 120, an exterior part 122, and a peripheral part 121, and a battery element 124 is enclosed therein. The exterior part 122 is a flat plate and has a peripheral part 123. Moreover, the accommodating part 120 forms a rectangular box-shaped recessed part, and the peripheral part 121 protrudes outward from the three peripheral parts in the shape of a flange, respectively. After the battery element 124 is accommodated in the accommodating part 120, the exterior part 122 is covered, and then the peripheral part 121 of the accommodating part 120 and the peripheral part 123 of the external part 122 are heated in a reduced pressure (preferably vacuum) atmosphere. The battery element 124 is sealed by airtight bonding by a technique such as fusion (heat sealing), thermocompression bonding, or ultrasonic welding.
[0080]
FIG. 13 is a diagram for explaining a third embodiment of a lithium secondary battery. In the lithium secondary battery shown here, a battery element 134 is enclosed in a shape-variable packaging body, and this shape-variable packaging body has a housing part 130, an exterior part 132, and a peripheral part 131, and the battery element 134 is enclosed. The The accommodating part 130 forms a rectangular box-shaped concave part, and the peripheral part 131 protrudes from the periphery. The exterior part 132 forms a rectangular box-like convex part, and the peripheral part 133 protrudes from the periphery. After the battery element 134 is accommodated in the accommodating portion 130, the exterior portion 132 is covered, and then the peripheral portion 131 of the accommodating portion 130 and the peripheral portion 133 of the external portion 132 are in a reduced pressure (preferably vacuum) atmosphere. The battery element 134 is encapsulated by airtight bonding by a technique such as heat fusion (heat sealing), thermocompression bonding, or ultrasonic welding. In addition, the exterior part 132 and the accommodating part 130 may be separate bodies.
[0081]
FIG. 14 is a diagram for explaining a third embodiment of a lithium secondary battery. In the lithium secondary battery shown here, the battery element 144 is enclosed in a shape-variable package. The battery element 144 includes a pair of leads 145a and 145b. Further, the shape-variable packaging body has two pieces of a first piece 140 and a second piece 142, which are formed by folding a flat sheet along the central side 146 into a two-fold shape. . The first piece 140 has a peripheral portion 141, and the second piece 142 has a peripheral portion 143.
[0082]
FIG. 15 is a plan view for explaining a state in which the battery element 144 is enclosed in the lithium secondary battery shown in FIG. The battery element 144 is sealed by joining the peripheral portion 141 of the first piece 140 and the peripheral portion 143 of the second piece 142 of the shape-variable package. In this case, both ends of the shape-variable packaging body may be bonded to form a cylinder, and after the battery element 144 is stored inside, the upper and lower sides of the cylinder may be further bonded and sealed. In either case, the first piece 140 and the second piece 142 of the shape-variable packaging body are overlapped before or after the insulating material (not shown) is attached near the tab (not shown) of the battery element 144. The battery element 144 is encapsulated. Moreover, it is preferable that the joining piece part of the 1st piece 140 and the 2nd piece 142 is bent along the battery element 144, and is fastened.
[0083]
FIG. 16 is a diagram for explaining the first embodiment of the unit battery element of the lithium secondary battery. In the unit battery element shown here, a positive electrode composed of a positive electrode current collector 162 and a positive electrode material layer 163, a spacer 164 impregnated with an electrolyte, and a negative electrode composed of a negative electrode material layer 165 and a negative electrode current collector 166 are laminated. . A positive electrode tab 160 a extends from the positive electrode current collector 162 of the unit battery element, and a negative electrode tab 160 b extends from the negative electrode current collector 166. In order to suppress precipitation of lithium dendrite, the negative electrode is made larger than the positive electrode. In order to prevent a short circuit, the spacer 164 is made larger than the positive electrode and the negative electrode. By making the spacer 164 larger than the positive and negative electrodes, the protruding portions of the spacers of the unit battery element can be fixed. A plurality of the unit battery elements are stacked to form a battery element. In the battery element according to the present embodiment, the unit battery elements are stacked in a forward posture with the positive electrode on the upper side and the negative electrode on the lower side. On the contrary, when unit cell elements in a reverse posture (not shown) with the positive electrode on the lower side and the negative electrode on the upper side are alternately stacked, the unit cell elements adjacent in the stacking direction have the same polarity ( That is, the positive electrodes and the negative electrodes are laminated so as to face each other.
[0084]
FIG. 17 is a diagram for explaining the form of the positive electrode or the negative electrode. The positive electrode 170 shown here includes a tab 170a, a positive electrode current collector 171a, and a positive electrode material layer 172a. The positive electrode current collector 171a is used as a core material, and a positive electrode material layer 172a is laminated on both surfaces thereof. Similarly, the negative electrode 173 includes a tab 173b, a positive electrode current collector 174b, and a positive electrode material layer 175b. The positive electrode current collector 174b is used as a core material, and a positive electrode material layer 175b is laminated on both surfaces thereof.
[0085]
FIG. 18 is a diagram for explaining a second embodiment of the unit battery element. The unit battery element shown here has the positive electrode 170 and the negative electrode 173 shown in FIG. The positive electrode 170 has a tab 170a, the negative electrode 173 has a tab 173b, and the spacer 181 is impregnated with an electrolyte. The positive electrode 170 and the negative electrode 173 have a structure in which the spacers 181 are alternately stacked. In this case, the combination of a pair of positive electrode 170 and negative electrode 173 (strictly speaking, the thickness direction of the current collector (not shown) of the negative electrode 173 from the center in the thickness direction of the current collector (not shown) of the positive electrode 170) Corresponds to the unit battery element. The planar shape of the electrode is arbitrary, and can be a quadrangle, a circle, a polygon, or the like.
[0086]
Here, as described in the battery element shown in FIG. 16 and the positive electrode or negative electrode shown in FIG. 17, the current collectors 162 and 166 in the battery element shown in FIG. 16 and the current collector in the positive electrode 170 shown in FIG. The current collector 174b in the body 171a or the negative electrode 173 is usually provided with a lead coupling tab. In addition, when the electrode is square, a tab protruding from the positive electrode current collector is usually formed near the side of one side of the electrode, as in the battery element shown in FIG. 10, and the tab of the negative electrode current collector is formed. Is formed near the other side. Laminating a plurality of unit cell elements is effective in increasing the capacity of the battery. At this time, each of the tabs from each unit cell element is usually coupled in the thickness direction to be connected to the positive electrode. A negative terminal portion is formed. As a result, a large capacity battery element can be obtained.
[0087]
FIG. 19 is a diagram for explaining a portion where an insulating material is injected in lithium secondary electrons. The lithium secondary electrons shown here are those in which the battery element 194 is enclosed in a shape-variable package. The battery element 194 has a pair of leads 195 a and 195 b, and the pair of leads 195 a and 195 b extends from the end of the battery element 194. The shape-variable packaging body includes a storage portion 190, an exterior portion 192, and a peripheral portion 191. The storage portion 190 forms a rectangular box-shaped concave portion, and the peripheral portion 191 is formed outwardly in a flange shape from the four peripheral portions. Overhangs. The exterior part 192 is a flat plate having a peripheral part 193. After the battery element 194 is accommodated in the accommodating portion 190, the exterior portion 192 is covered, and then the peripheral portion 191 of the accommodating portion 190 and the peripheral portion 193 of the external portion 192 are heated in a reduced pressure (preferably vacuum) atmosphere. The battery element 194 is sealed by airtight bonding by a technique such as crimping or ultrasonic welding. In addition, the battery element 194 is covered with an insulating material (not shown) whose side surfaces near the terminal portion are injected from a plurality of locations (R1 to R6).
[0088]
FIG. 20 is an enlarged view of FIG. As shown here, the insulating material (not shown) is composed of a plurality of corners R1, R6 on the side end face of the battery element 194 and a plurality of locations R2, R3, R4, R5 on both sides of the pair of leads 195a, 195b. It is preferable to be injected. The injected insulating material permeates the entire side of the battery element 194 including the positive electrode terminal portion and the negative electrode terminal portion by an action such as capillary action.
[0089]
FIG. 21 is an enlarged view of FIG. Here, a lead 195a (or 195b) is shown that couples to a tab 210a (or 210b) of the battery element. As shown in this figure, when the insulating material is injected into the root portion of both sides of the lead 195a (or 195b) that couples to the tab 210a (or 210b), the injection point (center of the injection nozzle) is the tab 210a (or 210b) is preferably within 2 mm. Thus, when the insulating material is injected into the base portions on both sides of the lead 195a (or 195b) coupled to the tab 210a (or 210b), this insulating material fixes the protruding portions of the spacer used in the unit cell element. In addition, a configuration in which at least a part of the positive electrode terminal portion and the negative electrode terminal portion is covered with an insulating material is also obtained.
[0090]
FIG. 22 is a diagram for explaining a method of injecting an insulating material. As shown in this figure, in order to inject the insulating material, it is preferable to insert the nozzle 221 of the insulating material injection device 220 into the accommodating portion 190 and inject the insulating material into the side end surface of the battery element 194. The insulating material injection device 220 includes a plurality (six nozzles) of nozzles, and can inject a plurality of insulating materials at a time.
[0091]
In addition, FIG. 23 is a figure for demonstrating the structure of the spacer in a battery element. The battery element 234 shown here includes a positive electrode 231, a negative electrode 232, a spacer 233, a tab 231 a, and a lead 235 a, and the positive electrode 231 and the negative electrode 232 are stacked via the spacer 233. The positive electrode 231 has a tab 231a, and the plurality of tabs 231a are coupled to the lead 235a. The spacer 233 forms a protruding portion 233 a that slightly protrudes from the positive electrode 231 and the negative electrode 232, thereby preventing a short circuit between the positive electrode 231 and the negative electrode 232. By sticking the protruding portions 233a with an insulating material, the battery element 234 is restrained in the stacking direction, so that the battery element 234 is effectively prevented from being peeled off due to an increase in the internal pressure of the exterior material (case) during high temperature storage. can do. Needless to say, it is preferable to supply the insulating material over the entire side surface of the battery element 234 because the bonding of the shape-variable packaging body becomes strong.
[0092]
The thickness of the entire lithium secondary battery in which these battery elements are housed in a shape-variable package is usually 5 mm or less, preferably 4.5 mm or less, more preferably 4 mm or less, while usually 0.5 mm. The thickness is preferably 1 mm or more, more preferably 2 mm or more. In addition, for the convenience such as the mounting of the battery on the equipment, the battery element is enclosed in a shape-variable packaging body and molded into a preferable shape, and then, if necessary, these multiple lithium secondary batteries are further rigidly provided in an outer case. It is also possible to store it in the box.
[0093]
As a specific example of the shape variable packaging body used in this embodiment, a vacuum packaging bag made of a laminate film of a gas barrier layer and a polymer film layer is particularly preferable. Such a laminate film has a high gas barrier property, a thin film thickness, and a high shape variability. As a result, it can be made thinner and lighter as a package, and used as a battery exterior material. The capacity of the entire battery can be improved. The gas barrier layer in the laminate film is preferably aluminum that is lightweight and excellent in workability. Examples of the polymer film layer include various synthetic resins such as thermoplastics, thermoplastic elastomers, thermosetting resins, and plastic alloys.
[0094]
Next, in the present embodiment, as the inert gas used in the operation of holding the variable shape packaging body in which the battery element is sealed under reduced pressure in the pressurized atmosphere of inert gas, helium, neon, argon, etc. Examples include noble gas and nitrogen gas. Such an inert gas has a molecular volume of 3.5 × 10 5. ^-2 nm ^Three An inert gas mainly composed of the following molecules can be used. By using a molecular gas having such a molecular volume, it is possible to detect a minute leak portion as large as a water molecule. Among these, it is particularly preferable to use helium.
[0095]
The pressure in the pressurized atmosphere of such an inert gas is usually 0.2 MPa or more, and usually 15 MPa or less, preferably 5 MPa or less, more preferably 1 MPa or less. The time for holding the deformable packaging body in which the battery element is sealed under reduced pressure in a pressurized atmosphere of an inert gas is usually 1 minute or more, preferably 10 minutes or more, more preferably 30 minutes or more, while usually 5 Time or less, preferably 2 hours or less, more preferably 1 hour or less.
[0096]
Next, in the present embodiment, the pressure of the reduced-pressure atmosphere in the operation of holding the deformable packaging body in which the battery element is enclosed in a reduced-pressure atmosphere is not particularly limited, but is usually 1 Pa or more and atmospheric pressure or less, Specifically, the pressure is 0.1 MPa or less, preferably 50 Pa or less, more preferably 30 Pa or less. The holding time in the reduced-pressure atmosphere is sufficient if it is sufficient for the shape-variable packaging body to expand and deform, and is sufficient to reduce the pressure in the atmosphere. Although it does not specifically limit as holding time, Specifically, it is 1 minute or more normally. On the other hand, it is usually 1 hour or less, preferably 30 minutes or less, more preferably 20 minutes or less.
[0097]
Subsequently, in the present embodiment, a method of taking out the shape-variable packaging body in which the battery element is sealed under reduced pressure from the reduced-pressure atmosphere and returning it to the atmospheric pressure, and confirming whether the shape-variable packaging body is deformed or not will be described. Specifically, by the method of confirming the presence or absence of swelling of the package and the peeling of the joint by visual observation, or by the method of confirming by touching (palpation) the presence or absence of looseness of the joint portion of the shape-variable package, Check for deformation of the shape-variable packaging. The looseness of the joint part of the shape-variable package means that the part is leaking. In a battery using a shape-variable packaging body, if there is a leak in the joint portion of the shape-variable packaging body, moisture will enter the packaging body, causing deterioration of the performance of the battery element housed in the packaging body or electrolyte hydrolysis. The risk of gas generation due to decomposition is particularly great. Therefore, according to the battery manufacturing method described in the present embodiment, after the battery element is sealed in the shape-variable packaging body, the above-described process is performed, so that the battery has a minute shape of the shape-variable packaging body. Therefore, it is possible to quickly and inexpensively extract a product in which a leak portion exists, and to provide a battery manufacturing method in which stable quality is maintained without deterioration of battery performance after shipment.
[0098]
Examples of electrical devices used as the power source for the lithium secondary battery in the present embodiment include notebook personal computers, pen input personal computers, personal digital assistants (PDAs), electronic book players, Telephone, cordless phone, pager, handy terminal, portable fax, portable copy, portable printer, headphone stereo, video movie, LCD TV, handy cleaner, portable CD, minidisc, electric shaver, transceiver, electronic notebook, calculator, memory Cards, portable tape recorders, radios, backup power supplies, motors, lighting equipment, toys, game equipment, road conditioners, watches, strobes, cameras, medical equipment (pacemakers, hearing aids, shoulder paddles) ), And the like.
[0099]
【The invention's effect】
Thus, according to the present invention, it is possible to quickly and inexpensively confirm the presence / absence of a minute leak portion of the shape-variable packaging body in which the package body is enclosed.
[Brief description of the drawings]
FIG. 1 (a), (b), and (c) are cross-sectional views of a laminate film.
FIG. 2 is a diagram of a shape-variable packaging body that accommodates a packaged body.
FIG. 3 is a diagram of a shape-variable packaging body in which an exterior material and a housing portion are a series of bodies.
FIG. 4 is a diagram of another embodiment of a shape-variable packaging body in which an exterior material and a housing portion are a series of bodies.
FIG. 5 is a diagram of a shape-variable package formed by bonding two laminated films together.
FIGS. 6A and 6B are diagrams illustrating the operation of a battery inspection method.
FIG. 7 is a view of an inspection case.
FIG. 8 is a diagram of a first embodiment of a lithium secondary battery.
9 is a cross-sectional view of the lithium secondary battery shown in FIG.
FIG. 10 is a diagram of battery elements used in the lithium secondary battery shown in FIG.
11 is a diagram for explaining a state in which the battery element is sealed in a shape-variable packaging body under reduced pressure in the battery of FIG.
FIG. 12 is a diagram of a second embodiment of a lithium secondary battery.
FIG. 13 is a diagram of a third embodiment of a lithium secondary battery.
FIG. 14 is a diagram of a fourth embodiment of a lithium secondary battery.
15 is a plan view of the lithium secondary battery in FIG. 14. FIG.
FIG. 16 is a diagram of a first embodiment of a unit cell element.
FIG. 17 is a diagram of another embodiment of a positive electrode or a negative electrode.
FIG. 18 is a diagram of a second embodiment of a unit cell element.
FIG. 19 is a view of a portion where an insulating material is injected.
FIG. 20 is an enlarged view of FIG. 19;
FIG. 21 is an enlarged view of FIG. 20;
FIG. 22 is a diagram of an insulating material injection method.
FIG. 23 is a diagram of a configuration of a spacer of a battery element.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Gas barrier layer, 20 ... Storage part, 24 ... Package to be packaged, 60 ... Inspection case, 61 ... Pressurized container, 62 ... Cylinder, 63 ... Depressurization container, 64 ... Rotary pump, 80 ... Storage part, 84 ... Battery Element, 85a, 85b ... Lead

Claims (7)

A battery element having a positive electrode, a negative electrode, and an electrolyte is enclosed in a shape-variable package under reduced pressure,
Holding the shape variable packaging body in which the battery element is sealed under reduced pressure in a pressurized atmosphere of an inert gas,
Thereafter, the shape-variable packaging body in which the battery element is sealed under reduced pressure is held in a reduced-pressure atmosphere,
Thereafter, the shape variable packaging body in which the battery element is sealed under reduced pressure is returned to atmospheric pressure, and the presence or absence of deformation of the shape variable packaging body is confirmed. The deformable packaging body includes a gas barrier layer and the inspection method of a battery according to claim 1 wherein the polymeric film layer is a vacuum packaging bag made of a laminate film laminated. The inert gas has a molecular volume of 3.5 × 10 ^-2 nm ³ The method for inspecting a battery according to claim 1 or 2, wherein the main component is the following molecule. Enclosing a battery element having a positive electrode, a negative electrode and an electrolyte in a form-variable packaging under reduced pressure;
Maintaining the shape-variable packaging body in which the battery element is sealed under reduced pressure in a pressurized atmosphere of an inert gas;
Thereafter, the step of holding the variable shape packaging body in which the battery element is sealed under reduced pressure in a reduced pressure atmosphere ;
After that, the method of manufacturing a battery includes a step of returning the shape variable packaging body in which the battery element is sealed under reduced pressure to atmospheric pressure and confirming the deformation of the shape variable packaging body. The battery manufacturing method according to claim 4, wherein the shape-variable package is a vacuum packaging bag made of a laminate film in which a gas barrier layer and a polymer film layer are laminated. The battery manufacturing method of battery according to claim 4 or 5, wherein the lithium secondary battery. The inert gas has a molecular volume of 3.5 × 10 ^-2 nm ³ The method for producing a battery according to any one of claims 4 to 6, wherein the following molecule is a main component.

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