JP5087943B2 - Battery pack and manufacturing method thereof - Google Patents

Description

  The present invention relates to a battery pack applied to, for example, a lithium ion secondary battery and a manufacturing method thereof.

  In recent years, portable electronic devices such as a camera-integrated video tape recorder, a mobile phone, or a laptop computer have become widespread, and their size and weight have been reduced. Along with this, the demand for battery packs used as power sources for portable electronic devices is growing rapidly, and in order to reduce the size and weight of the devices, the design of the battery pack is light and thin, and the inside of the devices It is required to efficiently use the storage space. As a battery pack that satisfies such requirements, a lithium ion secondary battery having a large energy density and output density is most suitable.

  As this type of battery pack, as shown in FIG. 5, a power generation element 100 in which a power generation element is wrapped with a laminate film 103 with positive and negative electrode leads 101 and 102 being led out is used. There is one in which the power generating element is covered with a hard aluminum exterior plate 104 formed into a flat cylindrical shape from the state (for example, Patent Document 1).

  In the battery pack described above, on the head side of the power generation element 100 that is one opening of the exterior plate 104, the positive and negative leads 101 and 102 are connected to the circuit board 105, and then the resin is placed in the opening of the exterior plate 104. A top cover 106, a circuit board 105, and a resin holder 107 for holding the circuit board are attached, and the power generation element 100 and the top cover 106 are thermally welded. On the other hand, on the bottom side of the power generation element 100, which is the other opening of the exterior plate 104, a resin bottom cover 108 is attached to the opening of the exterior plate 104, and the power generation element 100 and the bottom cover 108 are thermally welded. ing. Then, a label 109 describing appropriate matters is attached to the joint portion of the exterior material 104, and a submergence detection seal 110 is attached to the outside of the top cover 106.

The battery pack is filled with an adhesive or a molten resin (hot melt) between the power generation element 100 and each of the covers 106 and 108 on the head side and the bottom side of the power generation element 100, thereby The covers 106 and 108 and the exterior plate 104 are fixed to each other.
JP 2005-166644 A

  However, in the conventional battery pack as described above, the power generation element is covered with a hard aluminum exterior plate, and the power generation element and the covers on both sides are fixed by heat welding, so the number of processes is reduced. There is a problem that the time and cost for manufacturing increase, and there is a problem that the power generation element is easily affected by heat, and the power generation element may expand or the cover may be removed with expansion. It was a problem to solve these problems.

  The present invention has been made paying attention to the above-mentioned conventional problems, and can reduce the number of processes, time and cost involved in manufacturing, reduce the thermal influence on the power generation element, and improve quality. It aims at providing the battery pack which can implement | achieve stabilization.

  The battery pack of the present invention includes a power generation element formed by packaging a power generation element with a laminate film with the positive and negative electrode leads led out, a circuit board connected to the positive and negative electrode leads, the circuit board including the molten resin The top cover integrated on the head side of the power generation element using the same, the bottom cover integrated on the bottom side of the power generation element using the same molten resin, and the outer periphery of the power generation element integrated with both covers are covered. More preferably, the pressure-sensitive adhesive label is provided on the outer periphery of the power generation element in which the two covers are integrated with a soft aluminum pressure-sensitive adhesive sheet interposed therebetween. It is a means to solve the problem.

  In addition, the battery pack manufacturing method of the present invention provides a method for deriving the positive and negative electrode leads when manufacturing a battery pack having a power generation element formed by packaging a power generation element with a laminate film with the positive and negative electrode leads led out. A top cover including a circuit board connected to the positive and negative electrode leads using a molten resin is integrated with the head side of the power generation element, which is the side, and a bottom cover is also formed using the molten resin on the bottom side of the power generation element. After the cover is integrated, an adhesive label is provided on the outer periphery of the power generation element in which both the covers are integrated. More preferably, after the top and bottom covers are integrated with the power generation element, the adhesive made of soft aluminum is used. A sheet is provided, and an adhesive label is provided on the outside of the adhesive sheet, and the above structure is used as a means for solving the conventional problems.

  According to the battery pack and the manufacturing method thereof of the present invention, since the cover is integrated with the power generation element using the molten resin, and this is covered with the adhesive label, the heat welding process that has been conventionally performed is abolished, Regarding manufacturing, it is possible to reduce the number of processes, shorten the time, reduce costs, save labor, etc., reduce the thermal effect on the power generation element, and realize quality stabilization, Since the outer skin is thinned by the use of the adhesive label, the volume efficiency can be increased after making the outer dimensions the same as the conventional one.

  In addition, according to the battery pack and the manufacturing method thereof of the present invention, the above effect can be obtained by employing a soft aluminum pressure-sensitive adhesive sheet, and sufficient strength equivalent to that of a conventional battery pack can be obtained. be able to.

  Hereinafter, an embodiment of a battery pack and a manufacturing method thereof according to the present invention will be described with reference to the drawings.

  As shown in FIG. 1, the battery pack of the present invention includes a power generation element 1 formed by packaging a power generation element with a laminate film 4 with positive and negative leads 2 and 3 being led out, and a molten resin (hot melt). A resin-made top cover 5 integrated on the head side of the power generation element 1 using the same, a resin-made bottom cover 6 integrated on the bottom side of the power generation element 1 using the same molten resin, and both covers 5, 6 is provided with an adhesive sheet 7 covering the outer periphery of the power generation element integrated with 6 and an adhesive label 8 covering the outer periphery of the adhesive sheet 7. A submergence detection seal 9 is attached to the outside of the top cover 6.

  The illustrated top cover 5 is formed by integrally molding a circuit board including a protection circuit and a resin holder for holding the circuit board, that is, insert molding the circuit board including the holder. After the circuit board is connected to the negative electrode leads 2 and 3, the negative electrode leads 2 and 3 are integrated with the power generation element 1 using the injection jig 10 shown in FIG. 2.

  As the hot melt resin, EVA (EVA: ethylene vinyl acetate copolymer), PP (polyolefin copolymer), PA (polyamide), SR (synthetic rubber), or the like is used. The EVA-based resin can be appropriately used with a melting temperature of 80 to 110 degrees and a curing time of 5 to 60 seconds. PP, PA, SR, polyimide, and the like can be appropriately used within a melting temperature of 100 to 150 degrees and a curing time of 10 seconds to 10 minutes.

  The injection jig 10 includes a main mold 11 that houses the power generation element 1 and both covers 5, 6, plates 12 and 13 disposed at both ends of the main mold 11, and seal rings 14 and 15 disposed on both sides of the power generation element 1. It has. Both plates 12 and 13 are provided with a supply hole 16 and a discharge hole 17 communicating with two through holes formed in the covers 5 and 6 in advance.

  The injection jig 10 accommodates the power generation element 1 and the covers 5 and 6, and forms a space between the power generation element 1 and the covers 5 and 6 at the positions of the seal rings 14 and 15. In this state, the molten resin is pressurized and supplied from the supply holes 16 of the plates 12 and 13 and supplied until the molten resin overflows from the discharge holes 17. Then, the power generation element 1 and the covers 2 are both cooled and cured. , 3 are integrated.

  Next, in the battery pack and the manufacturing method thereof according to the present invention, after removing the burrs of the molten resin, the adhesive sheet 7 is attached to the outer periphery of the power generation element 1 in which the covers 5 and 6 are integrated. As shown in FIG. 3 (a), the adhesive sheet 7 is formed by sequentially laminating a soft aluminum layer 7A, an adhesive layer 7B, and a release paper 7C impregnated with silicon, and the release paper 7C is peeled off. Affix to the power generation element 1 without gaps.

  The soft aluminum layer 7A plays the most important role of protecting the contents by preventing the ingress of moisture, oxygen and light in addition to improving the strength of the exterior material, and is suitably made of stainless steel or iron with nickel plating as a material. Although it can be used, aluminum (Al) is most preferable from the viewpoint of lightness, extensibility, cost and ease of processing, and aluminum such as 8021O or 8079O is particularly preferable.

  Thereafter, in the battery pack and the manufacturing method thereof according to the present invention, the pressure-sensitive adhesive label 8 is adhered to the outside of the pressure-sensitive adhesive sheet 7. As shown in FIG. 3B, the pressure-sensitive adhesive label 8 is formed by laminating an ink adhesive 8B, an ink 8C, and a UV coating 8D in this order on the upper surface of the resin layer 8A, and an adhesive layer 8E on the lower surface of the resin layer 8A. The release paper 8F impregnated with silicon is laminated in order, and the release paper 8F is peeled off and attached to the outside of the adhesive sheet 7 without a gap.

  FIG. 4 is a flowchart for comparing the conventional battery pack manufacturing method and the battery pack manufacturing method of the present invention.

  In the conventional battery pack manufacturing method, a hard aluminum exterior plate is cut into a schematic shape in step S101, the exterior plate sealing process is entered in step S102, and trimming is performed to form details of the exterior plate in step S103. In step S104, the exterior plate is temporarily fixed, and in step S105, the exterior plate is permanently fixed.

  Next, the circuit board (PWB) is mounted in step S106, the positive and negative leads are connected to the circuit board in step S107, the top cover, the circuit board and the holder are assembled in step S108, and the holder is impulsed into the power generation element in step S109. Weld.

  Then, after applying the cell terrace adhesive in step S110, the top cover is completely fixed to one opening of the exterior material in step S111, and the bottom cover is fixed to the other opening of the exterior material in step S112. In step S113, the top cover and the bottom cover are heat-sealed. In step S114, an adhesive is injected into the exterior material, and the power generation element, each cover, and the exterior material are fixed to each other. After aging for 4 days in an environment of 5 ° C., the sample is sent to the inspection process (step S9).

  On the other hand, in the battery pack manufacturing method of the present invention, the positive and negative leads of the power generation element are connected to the circuit board previously integrated with the top cover in step S1, and the injection treatment shown in FIG. 2 is performed in steps S2 and S3. The power generation element and both covers are set on the tool, and molten resin (hot melt) is injected into the injection jig in steps S4 and S5. After the molten resin is cooled and hardened, deburring of the resin is performed in step S6, and step S7. After sticking the adhesive sheet in step S8, the adhesive label is stuck in step S8 and sent to the inspection step (step S9). Appropriate indications such as product numbers and precautionary notes can be displayed on the adhesive label.

  Thus, according to the battery pack manufacturing method of the present invention, the steps S101 to S105, S108, S109, S113, and S115 in the conventional manufacturing method are eliminated, and the number of manufacturing steps is significantly reduced. As a result, the manufacturing time can be shortened, the manufacturing cost can be reduced, and the labor can be saved.

  In addition, since the battery pack according to the present invention has less thermal influence on the power generation element 1 in its manufacture, there is no problem that the power generation element 1 expands or the cover is removed due to expansion, and the quality is stabilized. As compared with the conventional battery pack using a hard aluminum exterior plate, the outer cover is made of an adhesive sheet and an adhesive label, so that the outer skin becomes thinner, and as shown in Table 1 below. In addition, the volumetric efficiency can be increased after making the outer dimensions the same as the conventional one.

  As is apparent from Table 1, the battery pack of the present invention can increase the overall length of the battery element 1 by making the outer dimensions the same by eliminating the bottom heat seal, for example, by integrating the battery element and the cover. Moreover, by reducing the thickness of the outer skin, the overall width and thickness of the battery element 1 can be increased with the same outer dimensions. Thereby, the battery pack of the present invention. The volume of the battery element is increased by making the outer dimensions the same, thereby increasing the battery capacity.

  Furthermore, the battery pack of this invention and the conventional battery pack used as a comparative example were created, and these drop tests were done. In the battery pack of the present invention, a top cover and a bottom cover made of polycarbonate were prepared, and both the covers were integrated with the battery element using a molten resin (hot melt). At this time, polyamide was used for the hot melt, its melting temperature was 110 ° C., and the cooling time was 30 seconds. And after sticking the soft aluminum adhesive sheet shown to Fig.3 (a) on the outer side of the battery element which integrated said both covers, the adhesive label on the outer side shown in FIG.3 (b) further outside Was attached. In the conventional battery pack, the battery element is covered with a hard aluminum exterior plate, and a top cover and a bottom cover are thermally welded to one and the other openings of the exterior plate, respectively.

Then, 200 battery packs according to the present invention and 200 conventional battery packs were prepared, and a drop test was performed under the following conditions (1) to (3). Drop test
(1) Drop height: 1.1 m, fall surface: concrete, 6 surfaces and 4 corners of battery pack, 2 cycles each (20 times in total).
(2) Fall height: 1.0 m Falling surface: Concrete, 8 cycles (100 times in total) with the same test as (1).
(3) Drop height: IEC60068-2-32Ed (0.5M), Drop surface: Dropped 200 times with steel.
The results are shown in Table 2. Table 2 shows the number of defective products in 200 pieces.

  As is apparent from Table 2, the cover of the conventional battery pack was slightly removed, but the battery pack of the present invention did not have any cover removed. Even though the outer skin was thinned, it was found that it had sufficient mechanical strength.

  Hereinafter, the material of the battery element used for the battery pack of the present invention will be described in detail.

[Positive electrode]
The positive electrode has a positive electrode active material layer containing a positive electrode active material formed on both surfaces of the positive electrode current collector. The positive electrode current collector is made of a metal foil such as an aluminum (Al) foil, a nickel (Ni) foil, or a stainless steel foil.

  The positive electrode active material layer includes, for example, a positive electrode active material, a conductive agent, and a binder. These are uniformly mixed to form a positive electrode mixture, and this positive electrode mixture is dispersed in a solvent to form a slurry. Next, the slurry is uniformly applied on the positive electrode current collector by a doctor blade method or the like, dried at a high temperature, and the solvent is removed. Here, the positive electrode active material, the conductive agent, the binder, and the solvent only have to be uniformly dispersed, and the mixing ratio is not limited.

The positive electrode active material is mainly LiXMO ₂ (wherein M represents one or more transition metals, and x varies depending on the charge / discharge state of the battery and is usually 0.05 or more and 1.10 or less). A composite oxide of lithium and a transition metal is used. As the transition metal constituting the lithium composite oxide, cobalt (Co), Ni, manganese (Mn) or the like is used.

Specific examples of such a lithium composite oxide include LiCoO ₂ , LiNiO ₂ , LiMn ₂ O ₄ , LiNiyCo1-yO ₂ (0 <y <1). A solid solution in which a part of the transition metal element is substituted with another element can also be used. LiNi0.5Co0.5O _2, LiNi0.8Co0.2O ₂ and the like as an example. These lithium composite oxides can generate a high voltage and have an excellent energy density. _{Furthermore, TiS 2, MoS 2, NbSe} 2, V 2 O no lithium metal sulfides such as ₅ or may be used an oxide as the positive electrode active material.

  As the conductive agent, for example, a carbon material such as carbon black or graphite is used. As the binder, for example, polyvinylidene fluoride, polytetrafluoroethylene, polyvinylidene fluoride, or the like is used. Moreover, as a solvent, N-methylpyrrolidone etc. are used, for example.

  The positive electrode has a positive electrode terminal connected to one end of the current collector by spot welding or ultrasonic welding. The positive electrode terminal is preferably a metal foil or a mesh-like one, but there is no problem even if it is not a metal as long as it is electrochemically and chemically stable and can conduct electricity. Examples of the material for the positive electrode terminal include Al.

[Negative electrode]
The negative electrode is formed by forming a negative electrode active material layer containing a negative electrode active material on both surfaces of a negative electrode current collector. The negative electrode current collector is made of a metal foil such as copper (Cu) foil, Ni foil, or stainless steel foil.

  The negative electrode active material layer includes, for example, a negative electrode active material, a conductive agent if necessary, and a binder. These are uniformly mixed to form a negative electrode mixture, and this negative electrode mixture is dispersed in a solvent to form a slurry. Next, the slurry is uniformly applied on the negative electrode current collector by a doctor blade method or the like, dried at a high temperature, and the solvent is blown off to form a negative electrode active material layer. Here, the negative electrode active material, the conductive agent, the binder, and the solvent only have to be uniformly dispersed, and the mixing ratio is not limited.

As the negative electrode active material, lithium metal, a lithium alloy, a carbon material that can be doped / undoped with lithium, or a composite material of a metal material and a carbon material is used. Specific examples of carbon materials that can be doped / undoped with lithium include graphite, non-graphitizable carbon, graphitizable carbon, and the like. More specifically, pyrolytic carbons and cokes (pitch coke, needle coke). , Petroleum coke), graphites, glassy carbons, organic polymer compound fired bodies (phenol resins, furan resins, etc., calcined at an appropriate temperature), carbon fibers, activated carbon and other carbon materials are used. be able to. Furthermore, as a material that can be doped or undoped with lithium, a polymer such as polyacetylene or polypyrrole or an oxide such as SnO ₂ can be used.

  In addition, various types of metals can be used as materials capable of alloying lithium, but tin (Sn), cobalt (Co), indium (In), Al, silicon (Si), and alloys thereof can be used. Often used. When metal lithium is used, it is not always necessary to use powder as a coating film with a binder, and a rolled Li metal plate may be used.

  As the binder, for example, polyvinylidene fluoride, styrene butadiene rubber or the like is used. Moreover, as a solvent, N-methylpyrrolidone, methyl ethyl ketone, etc. are used, for example.

  Similarly to the positive electrode, the negative electrode has a negative electrode terminal connected to one end of the negative electrode current collector by spot welding or ultrasonic welding. The negative electrode terminal is preferably a metal foil or a mesh-like one, but there is no problem even if it is not a metal as long as it is electrochemically and chemically stable and can conduct electricity. Examples of the material for the negative electrode terminal include copper and Ni.

  In addition, although it is preferable that the positive electrode terminal and the negative electrode terminal are derived | led-out from the same direction, there is no problem even if it derive | leads out from which direction as long as a short circuit etc. do not occur and there is no problem in battery performance. Moreover, the connection place of a positive electrode terminal and a negative electrode terminal will not be restricted to said example, if the electrical contact has taken place and the attachment method.

[Electrolytes]
As the electrolyte, an electrolyte salt and a non-aqueous solvent that are generally used in lithium ion batteries can be used. Specific examples of the non-aqueous solvent include ethylene carbonate (EC), propylene carbonate (PC), γ-butyrolactone, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, dipropyl carbonate, ethyl propyl carbonate, and carbonates thereof. And other solvents in which hydrogen is substituted with halogen. One of these solvents may be used alone, or a plurality of these solvents may be mixed with a predetermined composition.

As the electrolyte salt, one that dissolves in the non-aqueous solvent is used, and a combination of a cation and an anion is used. As the cation, an alkali metal or an alkaline earth metal is used. The _{anion, Cl-, Br-, I-, SCN-} , ClO 4 -, BF 4 -, PF 6 -, CF 3 SO 3 - or the like is used. _{Specifically, LiPF 6, LiBF 4, LiN} (CF 3 SO 2) 2, LiN (C 2 F 5 SO 2) 2, LiClO 4 and the like. The electrolyte salt concentration is not a problem as long as it can be dissolved in the above solvent, but the lithium ion concentration is in the range of 0.4 mol / kg or more and 2.0 mol / kg or less with respect to the nonaqueous solvent. Is preferred.

  When the gel electrolyte is used, the gel electrolyte is obtained by gelling an electrolyte solution in which the electrolyte and the electrolyte salt are mixed with a matrix polymer. The matrix polymer is not particularly limited as long as it is compatible with a nonaqueous electrolytic solution obtained by dissolving an electrolyte salt in a nonaqueous solvent and can be gelled. Examples of such a matrix polymer include a polymer containing polyvinylidene fluoride, polyethylene oxide, polypropylene oxide, polyacrylonitrile, and polymethacrylonitrile in repeating units. Such a polymer may be used individually by 1 type, and may mix and use 2 or more types.

[Separator]
The separator is made of, for example, a porous film made of a polyolefin-based material such as polypropylene (PP) or polyethylene (PE), or a porous film made of an inorganic material such as a ceramic nonwoven fabric. A structure in which a porous film is laminated may be used. Among these, polyethylene and polypropylene porous films are the most effective.

  In general, the thickness of the separator is preferably 5 to 50 μm, more preferably 7 to 30 μm. If the separator is too thick, the amount of the active material filled decreases, the battery capacity decreases, and the ionic conductivity decreases and the current characteristics deteriorate. On the other hand, if the film is too thin, the mechanical strength of the film decreases.

[Production of power generation elements]
Next, using the positive electrode and the negative electrode on which the gel electrolyte layer is formed, the positive electrode, the separator, the negative electrode, and the separator are laminated and wound in this order, and the gel electrolyte solution prepared as described above is uniformly formed on the positive electrode and the negative electrode. A battery element is used. Then, the battery element is packaged with a soft laminate film and molded to produce a power generation element.

  The soft laminate layer plays the most important role of protecting the contents by preventing the ingress of moisture, oxygen and light in addition to improving the strength of the exterior material, and appropriately uses stainless steel or nickel plated iron as the material However, aluminum (Al) is most preferable in terms of lightness, extensibility, cost, and ease of processing, and aluminum such as 8021O or 8079O is particularly preferable. Further, the metal foil, the exterior layer, and the sealant layer are bonded together through adhesive layers.

It is a disassembled perspective view explaining one Embodiment of the battery pack of this invention. It is sectional drawing explaining the injection | pouring jig | tool applicable to the manufacturing method of the battery pack shown in FIG. It is sectional drawing (a) of an adhesive sheet, and sectional drawing (b) of an adhesive label. It is a flowchart for comparing the manufacturing method of the conventional battery pack and the manufacturing method of the battery pack of the present invention. It is a disassembled perspective view explaining the conventional battery pack.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Power generation element 2 3 Positive / negative electrode lead 4 Laminate film 5 Top cover 6 Bottom cover 7 Adhesive sheet 8 Adhesive label

Claims (4)

A power generation element formed by wrapping a power generation element with a laminate film with the positive and negative electrode leads led out, a circuit board connected to the positive and negative electrode leads, a circuit board including the circuit board and using molten resin, A top cover integrated on the head side, a bottom cover integrated on the bottom side of the power generation element using the same molten resin, and an adhesive label covering the outer periphery of the power generation element integrated with both covers A battery pack characterized by that. 2. The battery pack according to claim 1, wherein the adhesive label is provided on an outer periphery of the power generation element in which the two covers are integrated with a soft aluminum adhesive sheet interposed therebetween. When producing a battery pack having a power generation element in which the positive and negative electrode leads are led out to the outside and the power generation element is packaged with a laminate film, it is melted on the head side of the power generation element that is the lead-out side of the positive and negative electrode leads. The top cover including the circuit board connected to the positive and negative electrode leads is integrated using resin, and the bottom cover is also integrated using the molten resin on the bottom side of the power generation element, and then both the covers are integrated. A method for producing a battery pack, characterized in that an adhesive label is provided on the outer periphery of the generated power generation element. The method for manufacturing a battery pack according to claim 3, wherein after the top and bottom covers are integrated with the power generation element, an adhesive sheet made of soft aluminum is provided, and an adhesive label is provided outside the adhesive sheet. .

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