JP4067337B2 - Battery pack manufacturing method and battery pack - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a battery pack incorporating a non-aqueous electrolyte secondary battery, and more particularly to a non-aqueous electrolyte battery that is optimal for use as a part of a case of an electric device, such as an electric device such as a mobile phone. The present invention relates to a battery pack for a secondary battery and a manufacturing method thereof.
[0002]
[Prior art]
A non-aqueous electrolyte secondary battery uses a stainless steel outer can. However, a non-aqueous electrolyte secondary battery (especially a so-called lithium ion battery using lithium cobaltate or the like as the positive electrode active material and graphite or the like as the negative electrode active material) has a battery voltage of 3.5 V or more when fully charged. Therefore, there is a problem of liquid leakage due to corrosion holes when stored for a long period of time. The corrosion of the outer can is because the iron component in the stainless steel used for the positive electrode outer can is dissolved as iron ions. Liquid leakage due to corrosion of a stainless steel outer can can be solved by using the outer can as a negative electrode. However, in the non-aqueous electrolyte secondary battery having this structure, it is necessary to use aluminum or an aluminum alloy as a terminal material that is connected to the positive electrode and takes out current to the outside, and stainless steel cannot be used. This is because if stainless steel is used as the terminal material, iron is dissolved. However, it is difficult to connect the terminal material made of aluminum to the aluminum core material of the positive electrode, so that the yield of the product is deteriorated. This is because the aluminum is welded together. Since the small non-aqueous electrolyte secondary battery has small terminal components, it is difficult to reliably connect the aluminum terminal material, which reduces the yield of the battery. In order to avoid this adverse effect, lithium batteries having an outer can made of aluminum have been developed. Aluminum has a high melting voltage and can prevent liquid leakage due to corrosion.
[0003]
[Problems to be solved by the invention]
However, the non-aqueous electrolyte secondary battery in which the outer can is made of a metal such as aluminum or stainless steel has a polarity on the surface of the electrode body (particularly, electrodes that are the upper and lower ends of the electrode body, usually a negative electrode in the case of a lithium ion battery). Is different from the outer can, it is necessary to insulate between the electrode body and the outer can. In order to realize this, the surface of the electrode body is covered with an insulating material and inserted into an outer can. In this structure, when the electrode body is inserted into the outer can, the insulating material may be deformed and cannot be sufficiently insulated. In particular, if a large electrode body is inserted in order to increase the charge / discharge capacity, this problem becomes serious.
[0004]
Furthermore, the nonaqueous electrolyte secondary battery in which the outer can is made of metal is manufactured by deep drawing a metal plate to produce a cylindrical outer can with a closed bottom, and the electrode body and the nonaqueous electrolyte solution are provided on the outer can. After opening, the opening is closed with a sealing plate. Since the non-aqueous electrolyte secondary battery having this structure has a predetermined standard size and standard shape, it is housed in a plastic case and processed into a battery pack in order to be mounted on a mounting portion of an electrical device. The plastic case of the battery pack is formed into an outer shape that can be detachably attached to the attachment portion of the electric device. In the battery pack having this structure, after a non-aqueous electrolyte secondary battery is manufactured as a finished product in a predetermined outer shape, the battery pack is further put in a case of the battery pack to have an outer shape adapted to various electric devices.
[0005]
Since this battery pack is a double-structured case composed of an outer can of a non-aqueous electrolyte secondary battery and a battery pack case, it is not only troublesome to manufacture but also increases the manufacturing cost. When converted from the manufacturing cost of the whole battery pack, the actual cost of double packaging is about 1/3 of the total cost. In order to reduce the cost of battery packs, a technology that reduces the packaging cost of battery outer cans and battery pack cases is eagerly desired. In packaging, it is extremely difficult to significantly reduce costs.
[0006]
Furthermore, it is difficult to design a conventional battery pack having a double packaging structure with a large capacity while reducing the outer shape, that is, to increase the capacity per unit volume. This is because it is extremely difficult to reduce the substantial thickness of the packaging. Even if the capacity of the non-aqueous electrolyte secondary battery can be increased, if the battery is stored in the battery pack case, the capacity of the battery pack increases. There is a harmful effect that cannot be made to capacity.
[0007]
The present invention has been developed for the purpose of solving such drawbacks. An important object of the present invention is to provide a battery pack that can be manufactured in a large quantity at a low cost by making the packaging structure remarkably simple while preventing liquid leakage due to metal corrosion, and the capacity of the entire battery pack can be increased. It is to provide a method.
[0008]
[Means for Solving the Problems]
The manufacturing method of the present invention accommodates an electrode body 2 composed of a positive electrode, a negative electrode, and a separator, and a nonaqueous electrolyte, and has a full charge voltage of 3.5 V or more and 5.0 V or less. This is a method of manufacturing a battery pack that is molded into a three-dimensional shape that is detachably attached to 20 attachment portions 21. This manufacturing method produces a plastic case 1 in which at least the inner surface and the surface of the case containing the electrode body 2 and the nonaqueous electrolyte are made of plastic. The plastic case 1 has an outer shape formed into a three-dimensional shape set on the mounting portion 21 of the electric device 20, an inner shape is formed into a shape into which the electrode body 2 is inserted, and the electrode body 2 and the nonaqueous electrolyte are placed therein. A battery outer can and an outer case for specifying the outer shape of the battery pack are manufactured as an integrally structured plastic case 1. The electrode body 2 and the non-aqueous electrolyte are placed directly inside the plastic case 1, and then the opening of the plastic case 1 is hermetically closed to manufacture a battery pack.
[0009]
The battery pack according to claim 2 of the present invention houses the electrode body 2 composed of a positive electrode, a negative electrode, and a separator, and a nonaqueous electrolyte, and has a full charge voltage of 3.5 V or more and 5.0 V or less. Further, the outer shape of the battery pack is formed into a three-dimensional shape that is detachably attached to the attachment portion of the electric device. In the battery pack, the case containing the electrode body 2 and the nonaqueous electrolyte is a plastic case 1 formed by molding plastic at least on the inner surface and the surface. The plastic case 1 has an outer shape formed into a three-dimensional shape that is set on the mounting portion 21 of the electric device 20, and an inner shape thereof is formed into a shape into which the electrode body 2 and the nonaqueous electrolyte are placed. In the battery pack, the outer case for the battery containing the electrode body 2 and the non-aqueous electrolyte and the outer case for specifying the outer shape of the battery pack are integrally formed by the plastic case 1, and the plastic case 1 is the case for the battery outer case and the battery pack. Both are used together.
[0010]
The electrode body 2 can use a lithium-containing compound as the positive electrode active material, and the negative electrode can be made of a material that can occlude and release lithium ions.
[0011]
The plastic case 1 can be laminated with a blocking layer 1c that prevents permeation of moisture and gas on the plastic layer. For example, the blocking layer 1c may be an inorganic material such as silica or alumina, a metal material such as aluminum or an aluminum alloy, or an organic compound such as polyvinylidene chloride, an ethylene vinyl alcohol copolymer, or a fluororesin. You can also. The plastic case 1 can be a plastic composite material formed by laminating a plurality of different plastic materials. Further, the plastic case 1 can be provided by integrally molding the locking portion 5 connected to the mounting portion 21 of the electric device 20 with plastic.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. However, the examples shown below illustrate a battery pack manufacturing method and a battery pack for embodying the technical idea of the present invention, and the present invention describes the battery pack manufacturing method and the battery pack as follows. Not specific.
[0013]
Further, in this specification, in order to facilitate understanding of the scope of claims, the numbers corresponding to the members shown in the examples are referred to as “the scope of claims” and “the means for solving the problems”. It is added to the member shown by. However, the members shown in the claims are not limited to the members in the embodiments.
[0014]
1 to 3 show a battery pack that incorporates a lithium ion secondary battery that is a non-aqueous electrolyte secondary battery. In this battery pack, the non-aqueous electrolyte secondary battery is a lithium ion secondary battery, but the battery pack is a non-aqueous electrolyte secondary battery other than the lithium ion secondary battery, and has a full charge voltage of 3.5 to A battery with 5V can also be used. In the illustrated battery pack, an electrode body 2 is housed in a plastic case 1 and hermetically sealed with a sealing plate 3.
[0015]
The non-aqueous electrolyte secondary battery stores an electrode body 2 composed of a positive electrode, a negative electrode, and a separator, and a non-aqueous electrolyte, and a full charge voltage is set to 3.5 V or more and 5.0 V or less. When two or more electrode bodies are connected in series in one battery pack, the voltage output from the battery pack is the sum of the voltages of the respective electrode bodies. The full charge voltage here is the electrode body. The voltage per unit is shown. The electrode body 2 is formed by insulating a positive electrode and a negative electrode with a separator. The positive electrode and the negative electrode are stacked on each other with a separator interposed therebetween, and are wound in a spiral shape to form a multilayer stacked structure. The wound electrode body 2 is processed to a predetermined thickness by applying pressure from both sides. However, the electrode body 2 can also be manufactured by laminating a plurality of positive electrodes and negative electrodes cut into a predetermined shape via a separator.
[0016]
The positive electrode is manufactured as follows. Lithium cobaltate as an active material, graphite as a conductive agent, and polyvinylidene fluoride as a binder, respectively, at a solid content mass ratio of 90: 6: 4, N-methyl-2-pyrrolidone (NMP) The mixture is kneaded in a positive electrode mixture slurry. Next, after applying a specified amount of this positive electrode mixture slurry to an aluminum foil (thickness 15 μm) as a core, it is heated to evaporate NMP, adjusted to a specified thickness with a pressure roller, and then cut to a predetermined size The positive electrode is manufactured.
[0017]
The negative electrode is manufactured as follows. Graphite powder and a dispersion in which a rubber-based binder as a binder is dispersed in water are mixed at a solid content mass ratio of 95: 5 to obtain a negative electrode mixture slurry. Next, after applying a specified amount of this negative electrode mixture slurry to a copper foil (thickness 12 μm), it is heated to evaporate water, adjusted to a specified thickness with a pressure roller, and then cut into a predetermined size to form a negative electrode. To manufacture.
[0018]
The positive electrode and the negative electrode manufactured as described above are wound with a polyethylene microporous thin film separator sandwiched therebetween to produce a spiral electrode body, and this is pressed from both sides to obtain an electrode having a predetermined thickness. Let's say body 2.
[0019]
The plastic case 1 in which the electrode body 2 is placed has a three-dimensional structure in which the inner surface and the surface are molded with plastic, or the whole is molded with plastic, and the outer shape thereof is set on the mounting portion 21 of the electric device 20 as shown in FIG. It is formed into a shape, and the inner shape is formed into a shape into which the electrode body 2 and the non-aqueous electrolyte are placed. This plastic case 1 is an integrated structure of an outer can of a non-aqueous electrolyte secondary battery containing an electrode body 2 and a non-aqueous electrolyte and an outer case for specifying the outer shape of the battery pack. Used in both battery case and battery pack case. As shown in FIG. 4, the plastic case 1 into which the spiral electrode body 2 having a predetermined thickness by pressurization is formed is formed into an elongated cylindrical shape having both ends semicircular. Although not shown, a plastic case for storing an electrode body formed by laminating a large number of electrodes is processed into a cylindrical shape having an inner cross-sectional shape of a rectangle.
[0020]
The outer shape of the plastic case 1 is shaped so as to be detachably attached to the electric device 20, and the battery pack shown in the figure is shaped so as to project the collar portion 4 on both sides. A battery pack that is connected to the mounting portion 21 of the electric device 20 so as not to be detached is formed integrally with the locking portion 5 on the outer surface of the plastic case 1. In the battery pack shown in FIG. 1, a convex portion 5A inserted into a concave portion (not shown) provided in the mounting portion of the electric device is provided at the lower end to form a locking portion 5, and further, on the upper surface of the sealing plate 3, A concave portion 5B that guides an elastic convex portion (not shown) that elastically protrudes in the mounting portion of the electric device is provided as the locking portion 5.
[0021]
Although not shown, the battery pack of the present invention can be incorporated in a battery holder of an electric device. In this case, the battery pack has a shape in which the outer shape of the plastic case is matched with the shape of the battery holder of the electric device without providing a collar. By attaching a lid to the battery holder, the battery pack can be prevented from falling off. Such a battery pack has an advantage that the battery pack can be shared even if the appearance of the electric device is different if the shape of the battery holder is matched to the battery pack.
[0022]
Further, the plastic case 1 shown in FIGS. 4 and 5 has a blocking layer 1c for preventing moisture and gas permeation therein to reduce moisture and gas permeability. The blocking layer 1 c is laminated inside the entire plastic case 1. The blocking layer 1c is a metal layer such as aluminum or an aluminum alloy, or an inorganic layer such as silica or alumina. The plastic case 1 having the blocking layer 1c as a metal layer is manufactured by insert-molding a metal thin film, or is manufactured by insert-molding a metal molded body formed by pressing a metal.
[0023]
The plastic case 1 having the blocking layer 1c as a metal layer or an inorganic layer is manufactured by molding the inner case portion 1a located on the inner side and the outer case portion 1b located on the outer side as follows. The inner case portion 1a is molded with plastic. The inner case portion 1a is formed into a cylindrical shape having an inner shape that is optimal for the electrode body 2. The cylindrical inner case 1a is formed into a cylindrical shape with the bottom closed or the bottom open. A metal or an inorganic material is vapor-deposited on the outer surface of the cylindrical inner case portion 1a, and the entire outer surface of the inner case portion 1a is covered with a blocking layer 1c. Thereafter, the inner case portion 1a is temporarily fixed in a molding chamber for molding the outer case portion 1b, molten plastic is injected into the molding chamber of the outer case portion 1b, and the inner case portion 1a is inserted into the outer case portion 1b. Mold.
[0024]
As described above, the plastic case 1 in which the blocking layer 1c is laminated can block the permeation of moisture and gas by the blocking layer 1c. For this reason, the plastic case 1 can be molded with plastic that allows moisture and gas to pass therethrough. Therefore, most plastics such as polyethylene (PE), polypropylene (PP), nylon, ABS, EVA, vinyl chloride, polyester, etc. can be used for the plastic case 1 having this structure. On the other hand, it is preferable to use a plastic that does not dissolve or swell in the organic solvent used in the electrolytic solution for the inner case 1a that comes into contact with the electrolytic solution. Crystalline polymer (LCP), polyphenylene sulfide (PPS), polyethersulfone ( PES), polybutylene terephthalate (PBT), polyamideimide (PAI), polyphthalamide (PPA), polyether ether cane (PEEK) and the like can be used.
[0025]
As shown in FIG. 6, the plastic case 1 can also be formed of a plastic composite material in which different types of plastics are laminated. The plastic case 1 has an airtight plastic 1d that can prevent moisture and gas from passing therethrough. Fluorine resin, polyvinylidene chloride, ethylene vinyl alcohol copolymer, etc. can be used for the airtight plastic 1d. This plastic case 1 is manufactured as follows. The inner case portion 1a is molded, the inner case portion 1a is temporarily fixed in the molding chamber of the mold, and the airtight plastic 1d is molded on the outer surface of the inner case portion 1a, and the inner case portion is formed on the airtight plastic 1d. Insert 1a. Further, the inner case portion 1a is temporarily fixed in a molding chamber of a mold for forming the outer case portion 1b, and the inner case portion 1a is inserted when the outer case portion 1b is formed. The plastic case 1 in FIG. 6 has a three-layer structure in which an airtight plastic 1d is provided between the inner case 1a and the outer case 1b. The plastic case is formed by molding the inner case with an airtight plastic. Further, a two-layer structure formed by molding an outer case part on the outer side thereof can also be used. Since the plastic case with this structure is also an airtight plastic and prevents moisture and gas from passing therethrough, other plastics can be molded from most plastics in the same manner as the plastic case 1 in FIG.
[0026]
The plastic case 1 fixes the sealing plate 3 to the opening with the electrode body 2 inserted. Since the sealing plate 3 is welded to the plastic case 1 and is securely fixed, the plastic case 1 is formed of thermoplastic plastic. However, the plastic case 1 can be molded from thermosetting plastic and the sealing plate 3 can be adhered and fixed.
[0027]
The plastic case 1 formed of thermoplastic plastic can be easily fixed with the sealing plate 3 by ultrasonic welding. The sealing plate 3 welded to the plastic case 1 also has a welded surface with the sealing plate 3 formed of a thermoplastic plastic. The plastic case 1 and the sealing plate 3 shown in FIGS. 5 and 6 are provided with a ridge 6 on one side and a connecting groove 7 for guiding the ridge 6 on the other side for reliable welding. The plastic case 1 and the sealing plate 3 are firmly and airtightly welded by ultrasonic welding while the ridge 6 is put in the connecting groove 7.
[0028]
As shown in FIGS. 1 and 7, the sealing plate 3 is formed of plastic as a whole, and the electrode terminal 8 including the positive electrode terminal 8 </ b> A and the negative electrode terminal 8 </ b> B is inserted and fixed so as to be exposed on the surface. . The sealing plate 3 is fixed by inserting a current collecting plate 9 composed of a positive current collecting plate 9A and a negative current collecting plate (not shown) so as to be exposed in the plastic case 1 which is the lower surface thereof. The sealing plate 3 connects a current collecting base material 10 to electrode terminals 8 which are a positive electrode terminal 8A and a negative electrode terminal 8B. The current collecting base material 10 is embedded in the sealing plate 3 and electrically connects the positive electrode terminal 8A to the positive electrode current collecting plate 9A and the negative electrode terminal 8B to the negative electrode current collecting plate. Further, the current collecting base material 10 shown in the figure is partially cut into a fusing portion 11 so that the fusing portion is blown when an overcurrent flows. In the current collecting base material 10, when an overcurrent flows, the fusing part 11 is blown by the current and cuts off the current flowing through the battery pack. Further, the sealing plate 3 shown in the figure is provided with an injection hole 12 for injecting a non-aqueous electrolyte, and the injection hole 12 is airtightly closed with a sealing plug 13. In this battery pack, an electrode body 2 is placed in a plastic case 1 to fix a sealing plate 3, a nonaqueous electrolyte is injected from an injection hole 12 of the sealing plate 3, and then the injection hole 12 is closed with a sealing plug 13. . In the battery pack, before the sealing plate 3 is fixed to the plastic case 1, the electrode body 2 is inserted and then the nonaqueous electrolyte is inserted, and the opening portion of the plastic case 1 is airtightly closed by the sealing plate 3. You can also. In this battery pack, it is not necessary to provide the non-aqueous electrolyte injection hole 12 in the sealing plate 3. Further, the sealing plate 3 shown in the figure is partially formed thinly and provided with a safety valve 14. The safety valve 14 is opened when the pressure in the plastic case 1 becomes higher than the set pressure, and prevents pressure destruction of the plastic case 1.
[0029]
In the illustrated battery pack, the bottom of the can which is the lower end opening of the plastic case 1 is closed with a plastic bottom lid 15. In the battery pack having this structure, the plastic for molding the bottom lid 15 can be molded from a plastic having a better buffering force than the plastic case 1, such as ABS resin. This battery pack can improve impact strength when dropped. However, in the battery pack, the plastic case 1 can be molded into a closed shape at the bottom. This battery pack does not need to close the bottom of the plastic case 1 with a separately formed bottom lid, and can be mass-produced at low cost.
[0030]
【The invention's effect】
The present invention has an advantage that the packaging structure can be made extremely simple and mass-produced at a low cost and the capacity of the entire battery pack can be increased while preventing liquid leakage due to metal corrosion. The battery pack of the present invention and the method of manufacturing the same use a case in which an electrode body and a nonaqueous electrolyte are placed as a plastic case formed by molding plastic at least on the inner surface and the surface. It is molded into a three-dimensional shape that is set in the mounting part of the battery, and the inner shape is molded into a shape that contains the electrode body and nonaqueous electrolyte, and the plastic case is used in both the battery case and the battery pack case. Because.
[0031]
As described above, the structure in which the plastic case is used in both the battery outer can and the battery pack case, as in the past, is a dual structure consisting of the outer can of the nonaqueous electrolyte secondary battery and the battery pack case. As a result, the packaging structure can be significantly simplified. Therefore, the manufacturing cost can be reduced and mass production can be performed at low cost, and the substantial thickness of the packaging can be reduced to increase the capacity of the entire battery pack. In addition, since the outer can which is a plastic case does not corrode like a metal outer can, there is no fear of liquid leakage due to metal corrosion.
[Brief description of the drawings]
1 is a partial cross-sectional perspective view of a battery pack according to an embodiment of the present invention. FIG. 2 is a front view of the battery pack shown in FIG. 1. FIG. 3 is a state in which the battery pack shown in FIG. FIG. 4 is an enlarged horizontal sectional view of the plastic case of the battery pack shown in FIG. 1. FIG. 5 is an enlarged vertical sectional view of the plastic case of the battery pack shown in FIG. FIG. 7 is an enlarged vertical sectional view showing an example. FIG. 7 is an enlarged sectional perspective view of the battery pack shown in FIG.
DESCRIPTION OF SYMBOLS 1 ... Plastic case 1a ... Inner case part 1b ... Outer case 1c ... Barrier layer 1d ... Airtight plastic 2 ... Electrode body 3 ... Sealing plate 4 ... Gutter part 5 ... Locking part 5A ... Convex part 5B ... Concave part 6 ... Convex line DESCRIPTION OF SYMBOLS 7 ... Connecting groove 8 ... Electrode terminal 8A ... Positive electrode terminal 8B ... Negative electrode terminal 9 ... Current collecting plate 9A ... Positive electrode current collecting plate 10 ... Current collecting base material 11 ... Fusing part 12 ... Injection hole 13 ... Sealing plug 14 ... Safety valve 15 ... Bottom lid 20 ... Electrical equipment 21 ... Mounting part

Claims (6)

The electrode body (2) composed of a positive electrode, a negative electrode, and a separator, and a non-aqueous electrolyte are accommodated, and the full charge voltage is set to 3.5 V or more and 5.0 V or less, and the outer shape is mounted on the electric device (20). A battery pack manufacturing method formed into a three-dimensional shape that is detachably attached to the part (21),
Produce a plastic case (1) with plastic on at least the inner surface and surface of the case containing the electrode body (2) and non-aqueous electrolyte. Molded into a three-dimensional shape to be set in the part (21), the inner shape is molded into a shape to contain the electrode body (2), and the battery can and battery pack containing the electrode body (2) and the nonaqueous electrolyte The outer case for specifying the outer shape is manufactured as an integral plastic case (1), and the electrode body (2) and the non-aqueous electrolyte are directly placed inside the plastic case (1), and then the plastic case (1) A battery pack manufacturing method, wherein the opening of the battery pack is hermetically closed. The electrode body (2) composed of a positive electrode, a negative electrode, and a separator and a non-aqueous electrolyte are accommodated, and the full charge voltage is set to 3.5 V or more and 5.0 V or less, and the outer shape of the electric device (20). A battery pack formed into a three-dimensional shape that is detachably attached to the attachment part (21),
The case containing the electrode body (2) and the non-aqueous electrolyte is a plastic case (1) formed by molding plastic at least on the inner surface and the surface, and this plastic case (1) is externally mounted with electrical equipment (20). Molded into a three-dimensional shape set in the part (21), and the inner shape is molded into a shape containing the electrode body (2) and the nonaqueous electrolyte,
The battery case that contains the electrode body (2) and the non-aqueous electrolyte and the outer case that specifies the outer shape of the battery pack are integrated in a plastic case (1), and the plastic case (1) is the battery case and battery. A battery pack characterized by being used in both cases of the pack. The battery pack according to claim 2, wherein the positive electrode active material constituting the electrode body (2) is made of a lithium-containing compound, and the negative electrode is made of a material capable of inserting and extracting lithium ions. The battery pack according to claim 2, wherein the plastic case (1) is formed by laminating a blocking layer (1c) that prevents permeation of moisture and gas on the plastic layer. The battery pack according to claim 2, wherein the plastic case (1) is a plastic composite material in which a plurality of plastics of different materials are laminated. The battery pack according to claim 2, wherein the plastic case (1) is integrally formed of plastic and has a locking portion (5) connected to the mounting portion (21) of the electric device (20).

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