JP2012146516A - Battery with resin film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery with a resin film, in which, when a resin film for insulation is constructed or a heat cycle is applied thereon, generation of local stress in the resin film is prevented, so that the durability of the resin film for insulation is improved.SOLUTION: A battery with a resin film includes a resin film 22 on a surface of a battery container 1, and has a recessed part 21 at at least one portion of a side face of the battery container 1. In the battery with a resin film, a filler 23 is buried in the recessed part 21.

Description

  The present invention relates to a battery with a resin film provided with a resin film on the surface of a battery container.

  Conventionally, in a battery covered with a metal outer can (battery container), for example, as described in Patent Literature 1 and Patent Literature 2, a lead terminal attached to a lid contacts the outer peripheral surface of the outer can. In order to prevent an external short circuit from occurring, an insulating resin film (such as a heat-shrinkable tube or an insulating tube) is provided so as to cover the outer peripheral surface of the outer can.

  By the way, when manufacturing such a battery, for example, after an electrode group or the like is loaded in the outer can, a lid member, a gasket, or the like is installed in the opening of the outer can and integrated by caulking technology. At this time, a concave portion is provided in advance on the side surface of the outer can in order to hold the lid member integrated by caulking.

  In the conventional techniques disclosed in Patent Literature 1 and Patent Literature 2, the resin film and the surface of the outer can are not in contact with each other at the portion where the concave portion is formed, and the resin film floats from the inner surface of the concave portion. Yes. In the drawing of Patent Document 1, the resin film in the concave portion is drawn horizontally without being curved, but actually, as described in Patent Document 2, the resin film is slightly curved toward the concave portion side. is doing.

  In the above-described conventional technology, for example, the residual stress generated in the resin film when the outer can is covered with the insulating resin film, or the repeated heat load is applied to the resin film due to the use of the battery. There is also a possibility that the portion of the concave portion is distorted, and in the worst case, the resin film may be broken (open a hole) in the concave portion.

JP 2006-128010 A JP 2004-158303 A

  In view of the above-described conventional situation, the present invention prevents local stress from being generated in a resin film when an insulating resin film is applied or when a thermal cycle is applied, thereby insulating resin film. An object of the present invention is to provide a battery with a resin film with improved durability.

  In order to solve the above problems, for example, the configuration described in the claims is adopted. The present application includes a plurality of means for solving the above-mentioned problems. To give an example, in the battery-equipped battery having a resin film on the surface of the battery container and having a recess in at least one place on the side surface of the battery container. The filling material is embedded in the recess, or a filling material formed in accordance with the shape of the recess is inserted.

According to the present invention, when the filler and the resin film are in contact with each other, local stress generation in the resin film in the vicinity of the recess is prevented. Therefore, the durability of the resin film can be improved when the battery can is covered with an insulating resin film or in an environment where a thermal cycle is applied.
Problems, configurations, and effects other than those described above will be clarified by the following description of embodiments.

It is sectional drawing of the battery-equipped battery which concerns on the 1st Embodiment of this invention. It is a disassembled perspective view of the battery with a resin film which concerns on the 1st Embodiment of this invention. It is sectional drawing of the battery-equipped battery which concerns on the 2nd Embodiment of this invention. It is a flowchart which shows the manufacturing process of the battery-equipped battery which concerns on the 1st Embodiment of this invention. It is a flowchart which shows the manufacturing process of the battery-equipped battery which concerns on the 2nd Embodiment of this invention.

Hereinafter, the present invention will be described in detail.
First, a first embodiment of the present invention will be described with reference to FIGS. This 1st Embodiment is an example of the cylindrical lithium ion secondary battery which is one of the secondary batteries for vehicles. As shown in the exploded perspective view of FIG. 2, a positive electrode mixture 16 is applied to both surfaces of a positive electrode 14 made of a metal thin film such as aluminum. A plurality of positive electrode tabs 12 are provided on the upper long side portion of the positive electrode 14 in the drawing. The negative electrode 15 is a metal thin film made of copper or the like, and a negative electrode mixture 17 is applied to both surfaces. A plurality of negative electrode tabs 13 are provided on the lower long side portion of the negative electrode 15 in the drawing.

  The positive electrode 14 and the negative electrode 15 are wound around a resin shaft core 7 via a porous and insulating separator 18, and the outermost separator is fixed with a tape 19 as a whole. An electrode group 8 is configured. At this time, the innermost periphery in contact with the shaft core 7 is the separator 18, and the outermost periphery is the separator 18 that covers the negative electrode 15.

  A positive electrode current collector plate 5 and a negative electrode current collector plate 6 are fixed to both ends of the tubular shaft core 7 by fitting. A positive electrode tab 12 is welded to the positive electrode current collector plate 5 by, for example, an ultrasonic welding method. Similarly, the negative electrode tab 13 is welded to the negative electrode current collector plate 6 by, for example, an ultrasonic welding method. Inside the battery container 1 serving also as a negative electrode terminal, a positive electrode current collector plate 5 and a negative electrode current collector plate 6 are housed in an electrode group 8 wound around a resin shaft core 7 as an axis. . At this time, the negative electrode current collector plate 6 is electrically connected to the battery container 1 via a negative electrode lead (not shown). Thereafter, the nonaqueous electrolytic solution 20 is injected into the battery container 1.

  A gasket 2 is provided between the upper lid portion composed of the upper lid 3 and the upper lid case 4 and the battery container 1, and the opening of the battery container 1 is sealed and electrically insulated by the gasket 2. The upper lid portion having conductivity is disposed on the positive electrode current collector plate 5, and one of the positive electrode leads 9 is welded to the upper lid case 4 and the other is welded to the positive electrode current collector plate 5. Are electrically connected to the positive electrode.

  The positive electrode mixture 16 includes a positive electrode active material, a positive electrode conductive material, and a positive electrode binder. As the positive electrode active material, lithium oxide is preferably used. Examples include lithium cobaltate, lithium manganate, lithium nickelate, lithium iron phosphate, lithium composite oxide (lithium oxide containing two or more selected from cobalt, nickel, and manganese). The positive electrode conductive material is not particularly limited as long as it is a substance capable of assisting transmission of electrons generated by the occlusion / release reaction of lithium ions in the positive electrode mixture to the positive electrode 14. Examples of the positive electrode conductive material include graphite and acetylene black. The positive electrode binder can be applied as long as it is capable of binding the positive electrode active material and the positive electrode conductive material, and the positive electrode mixture 16 and the positive electrode 14, and is a material that does not deteriorate significantly by contact with the non-aqueous electrolyte. is there. Examples of the positive electrode binder include polyvinylidene fluoride (PVDF) and fluororubber.

  The method for forming the positive electrode mixture 16 is not particularly limited as long as the positive electrode mixture 16 can be formed on the positive electrode 14. As an example of a method for forming the positive electrode mixture 16, there is a method in which a dispersion solution containing a constituent material of the positive electrode mixture is applied onto the positive electrode 14 and dried. Examples of the coating method include a roll coating method and a slit die coating method. Examples of the solvent for the dispersion include N-methylpyrrolidone (NMP) and water. The coating thickness of the positive electrode mixture 16 is, for example, about 40 μm on one side of the positive electrode 14, but is not limited thereto.

  The negative electrode mixture 17 has a negative electrode active material, a negative electrode binder, and a thickener. Moreover, the negative mix 17 may have negative electrode electrically conductive materials, such as acetylene black, as needed. Graphite carbon is preferably used as the negative electrode active material. By using graphite carbon, a lithium ion secondary battery for a plug-in hybrid vehicle or an electric vehicle that requires a large capacity can be manufactured. Examples of the negative electrode binder include polyvinylidene fluoride (PVDF) and fluororubber. As the thickener, hydroxypropylcellulose (HPMC), methylcellulose (MC), polyvinylpyrrolidone (PVP), and carboxymethylcellulose (CMC). Is mentioned.

  The method for forming the negative electrode mixture 17 is not particularly limited as long as the negative electrode mixture 17 can be formed on the negative electrode 15. An example of a method for forming the negative electrode mixture 17 is a method in which a dispersion solution containing a constituent material of the negative electrode mixture is applied onto the negative electrode 15 and dried. Examples of the coating method include a roll coating method and a slit die coating method. Examples of the solvent for the dispersion solution include N-methyl-2-pyrrolidone and water. The coating thickness of the negative electrode mixture 17 is, for example, about 40 μm on one side of the negative electrode 15, but is not limited thereto.

As the non-aqueous electrolyte, a solution in which a lithium salt is dissolved in a carbonate solvent is preferably used. Examples of the lithium salt include lithium fluorophosphate (LiPF ₆ ), lithium fluoroborate (LiBF ₆ ), and the like. Examples of carbonate solvents include ethylene carbonate (EC), dimethyl carbonate (DMC), propylene carbonate (PC), methyl ethyl carbonate (MEC), or a mixed solvent of solvents selected from one or more of the above solvents. Can be mentioned.

  The battery container 1 is often made of metal in consideration of long-term reliability and strength. Therefore, the positive electrode and the negative electrode are insulated by the gasket 2. When the upper lid 3 and the upper lid case 4 are loaded into the battery container 1 via the gasket 2, a caulking technique is generally used. As shown in FIG. 1, the battery container 1 is molded by caulking the opening side portion, and a part group such as a gasket 2 is loaded into the battery container 1. At this time, a concave portion 21 as shown in FIG. 1 is formed before caulking at an appropriate position on the side surface of the battery container 1 for loading the parts group, thereby receiving a force. And in order to prevent the short circuit at the time of assembling as a battery and to improve the anti-corrosion resistance of the battery container 1, a resin film 22 such as a vinyl chloride film that contracts when heat is applied is applied to the exterior (heat shrink construction). For example, using a vinyl chloride film with characteristics such that the thickness is about 0.3 mm, the thermal shrinkage rate is 20% in the longitudinal direction of the battery, and the circumferential direction is 60%. By doing so, the shape of the resin film 22 is stabilized. In particular, the heat shrinkage rate in the circumferential direction affects the finish of the upper and lower surfaces of the battery, so it is necessary to set it to an appropriate heat shrinkage rate. The heat-shrinkable resin film 22 can be appropriately used as long as it has the same heat-shrinking property as a polyolefin film, in addition to the vinyl chloride film.

  When the concave portion 21 is formed on the side surface of the battery container 1 and the resin film 22 is applied, conventionally, the resin film 22 is in a floating state in the portion of the concave portion 21 as described in the drawing of Patent Document 2 above. Curves inward. Thereby, in the vicinity of the curved portion, residual stress is generated locally during thermal contraction, and thermal stress is locally generated during thermal cycle loading. Considering the durability of the resin film 22 for a long time, it is desirable that these residual stresses and thermal stresses are not generated. Therefore, the present invention is characterized in that a filler 23 made of a curable resin or the like is embedded in the recess 21 as shown in FIG. The filler 23 is preferably embedded so as to be at the same level as the surface of the battery container 1 (that is, so that the dent caused by the recess 21 is completely eliminated). A slight inward or slightly outward protrusion is acceptable. This is because if the state in which the resin film 22 described in the drawing of Patent Document 2 is floating in the recess 21 can be eliminated, it is possible to reduce residual stress and thermal stress generated in the corresponding part. After the resin 23 is cured to form the filler 23, the resin film 22 is heat-shrinked to obtain the battery with a resin film of the present invention.

  The filler 23 is preferably made of a curable resin. For example, various resins such as thermosetting, ultraviolet curable, and water vapor absorption curable can be used. In particular, a silicone resin is preferably used. For example, after the silicone resin is filled in the recesses, curing is completed after about 24 hours in an environment of normal temperature (25 ° C.) and relative humidity of 50 to 60%.

  Further, as another aspect, the construction is not easy as in the case of embedding the above-described curable resin, but with a resin such as polypropylene or polyethylene, a general technique such as injection molding or machining is used to make the recess 21 in advance. The same effect can be obtained by forming the filler 23 in accordance with the shape of this and inserting the filler 23 into the recess 21. In this case, the shape of the filler 23 can be appropriately set in consideration of the shape of the recess 21 and is preferably inserted into the entire recess 21. good. In the case of a cylindrical battery, it can be a ring-shaped or arc-shaped filler. For example, two semicircular fillers may be produced, and these may be combined and fitted into the entire circumference of the recess 21 from two directions.

  Furthermore, the case where the filler made of the curable resin described above is embedded and the case where a filler previously formed as a processed part is inserted may be appropriately combined. For example, a case where a plurality of arc-shaped fillers are inserted into the recesses, and a resin is further embedded in a gap formed between the fillers to be cured can be exemplified.

  Due to the filler 23, there is no recess in the contact surface between the battery container and the resin film, so that the local residual stress or thermal stress generated by the curvature of the resin film 22 becomes extremely small. Therefore, it becomes possible to improve the durability of the resin film.

  Below, the specific method for manufacturing the battery-equipped battery according to the first embodiment will be described with reference to FIG. First, a battery that has been completed up to the above-described caulking operation is prepared. Subsequently, in order to secure the adhesion between the material of the filler to be embedded at a later stage and the battery container 1, the exterior portion of the battery is washed with ethanol (step 101) to remove dust and oil from the exterior portion. Next, a silicone resin (for example, a silicone resin manufactured by Shin-Etsu Chemical Co., Ltd.) is filled in the concave portion on the side surface of the battery container (step 102). Thereafter, the excess silicone resin is removed with a spatula or the like and molded into a desired shape (step 103). At this time, it is preferable to fill a larger amount of silicone resin in consideration of the volume which changes in the next curing step. In this state, the battery is exposed to an environment of a temperature of 30 ° C. and a relative humidity of 60% for 24 hours or longer to cure the silicone resin (step 104). The filler 23 can be formed by the above steps. Thereafter, as shown in FIG. 1, the outside of the battery is covered with a resin film 22 and thermally contracted (step 105), thereby obtaining a target battery with a resin film.

  Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 3 is a cross-sectional view of the cylindrical battery according to the second embodiment. In the first embodiment described above, the filler 23 reduces the residual stress at the time of thermal contraction of the resin film 22 and the thermal stress at the time of the thermal cycle load, but it may still occur slightly. ing. These stresses are due to the difference in the coefficient of friction between the surface of the filler 23 made of resin or the like and the surface of the battery container 1. Therefore, in the second embodiment, as shown in FIG. 3, a curable resin or the like is embedded as the filler 23 and cured, and then a resin-based paint is applied to the surface of the battery container 1 and the resin. The same coating layer 24 is formed between the film 22 and between the filler 23 and the resin film 22. The paint for forming the coating layer 24 is not particularly limited as long as it is an insulating paint, and can be appropriately selected from various resin-based paints. The range in which the coating layer 24 is provided needs to be at least near the surface of the filler 23, but if possible, it is preferable to coat the entire surface of the battery including the surface of the battery container 1 and the surface of the filler 23. . After the resin-based paint is applied and dried, the resin film 22 is applied and thermally contracted in the same manner as in the first embodiment to obtain a battery with a resin film. Thereby, residual stress and thermal stress are further reduced, and the durability of the resin film is further improved.

  Below, the specific method for manufacturing the battery-equipped battery according to the second embodiment will be described with reference to FIG. First, a battery that has been completed up to the above-described caulking operation is prepared. Subsequently, in order to secure the adhesion between the material of the filler to be embedded at a later stage and the battery container 1, the exterior portion of the battery is washed with ethanol (step 101) to remove dust and oil from the exterior portion. Next, silicone resin (for example, silicone resin manufactured by Shin-Etsu Chemical Co., Ltd.) is filled in the concave portion on the side surface of the battery container (step 102). Thereafter, the excess silicone resin is removed with a spatula or the like and molded into a desired shape (step 103). At this time, it is preferable to fill a larger amount of silicone resin in consideration of the volume which changes in the next curing step. In this state, the battery is exposed to an environment of a temperature of 30 ° C. and a relative humidity of 60% for 24 hours or longer to cure the silicone resin (step 104). The filler 23 can be formed by the above steps. At this stage, each surface of the filler 23 and the battery container 1 has a different coefficient of friction with respect to the resin film. In order to eliminate this difference, an acrylic paint is applied by spraying to form a coating layer (step 106). It is only necessary to achieve a uniform friction coefficient on the surface. Therefore, it is sufficient that the thickness of the coating layer is sufficient to cover minute irregularities on the painted surface, specifically, 20 μm or more. Moreover, although it is preferable to coat the battery container surface more than the area | region which the resin film 22 covers, the coating should just be applied to the side surface of the battery container including the part in which the difference in a friction coefficient with respect to a resin film arises. After the coating is dried (step 107), as shown in FIG. 3, the outside of the battery is covered with a resin film 22 and thermally contracted (step 105), thereby obtaining a target battery with a resin film. In the second embodiment, in addition to the effect that the residual stress and the thermal stress are extremely reduced as described above, the coating layer 24 can be used even when the resin film 22 is not present or the case where the resin film 22 is broken. Therefore, the battery container 1 is insulated, and the corrosion resistance is not extremely lowered, and long-term reliability can be ensured.

  In the above-described embodiment, a cylindrical battery has been described as an example. However, when a resin film is applied on the surface of a battery container having a recess (dent) on the surface, it is naturally applicable. Therefore, the case where a resin film is applied to a battery container having a three-dimensional shape such as a rectangular parallelepiped is also included. In addition, this invention is not limited to above-described embodiment, Various modifications are included. For example, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. In addition, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

DESCRIPTION OF SYMBOLS 1 Battery container 2 Gasket 3 Upper cover 4 Upper cover case 5 Positive electrode current collecting plate 6 Negative electrode current collecting plate 7 Axial core 8 Electrode group 9 Positive electrode lead 12 Positive electrode tab 13 Negative electrode tab 14 Positive electrode 15 Negative electrode 16 Positive electrode mixture 17 Negative electrode mixture 18 Separator 19 Tape 20 Non-aqueous electrolyte 21 Recess 22 Resin film 23 Filler 24 Coating layer

Claims (3)

  A battery with a resin film comprising a resin film on a surface of a battery container, and having a recess at least at one location on a side surface of the battery container. The battery with a resin film, wherein a filler is embedded in the recess.   In the battery-equipped battery having a resin film on the surface of the battery container and having a recess in at least one side surface of the battery container, the resin in which a filler formed in accordance with the shape of the recess is inserted into the recess. Battery with film.   The battery with a resin film according to claim 1, wherein the same coating layer is provided between the surface of the battery container and the resin film and between the filler and the resin film.

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