JP4140311B2 - Method for manufacturing case for power storage element - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a case for a storage element.
[0002]
[Prior art]
Some batteries include a power generation element having a positive electrode, a negative electrode, and an electrolyte solution, which is covered and sealed with a film such as a laminate film, with only the leading ends of leads connected to the positive and negative electrodes of the power generation element protruding. For example, a card type battery is formed by storing a battery formed by sealing a power generation element with a laminate film in a card type outer case.
[0003]
As a battery formed by sealing a power generation element with a laminate film, for example, there is a battery in which the laminate film is bent as it is and the periphery is heat-sealed with the power generation element disposed on the surface of the laminate film.
[0004]
Moreover, the structure of the battery in which the power generation element is sealed with a laminate film is also adopted in the capacitor. That is, a capacitor is formed by sealing a charging / discharging element having an electrolytic solution and a pair of electrodes with a laminate film.
[0005]
In general, a laminate film used for a battery and a capacitor (hereinafter referred to as a power storage element) having the above-described configuration is formed by laminating a metal layer and a resin layer in order to ensure water resistance and insulation. Is formed. Specifically, it has a structure in which resin layers are laminated on at least both surfaces of a metal layer. In this laminate film, the metal layer ensures water resistance and the resin layer ensures insulation.
[0006]
However, since the innermost peripheral surface of the laminate film facing the power generation element and the charge / discharge element (hereinafter referred to as a power storage element) is required to have electrical insulation, the innermost peripheral surface is formed of a resin layer. Is required.
[0007]
In recent years, there has been a demand for higher performance in power storage elements, and the capacity has been increased by increasing the size of power storage elements of batteries and capacitors. When the physique of the electricity storage element becomes large (thickness increases), sealing is performed in a state where the laminate film on the peripheral edge of the electricity storage element is wrinkled. Sealing in a wrinkled state is likely to cause poor sealing, and if poor sealing occurs, the electricity storage element, particularly the electrolyte solution, leaks out or moisture is mixed in and the performance of the electricity storage element deteriorates. .
[0008]
In order to suppress the occurrence of such a sealing failure, a substantially concave storage element storing portion for storing the storage element is formed in advance by drawing, and the storage element is formed in the storage element storage section. An electricity storage device has been developed in which a laminate film is sealed in a state in which the is placed.
[0009]
For example, in Japanese Patent Application Laid-Open No. 2001-291497, a polymer battery is formed by folding in two using a laminate formed of at least a base material layer, a barrier layer, and a heat seal layer in which a recess is formed on one side or a recess is formed on both sides. A polymer battery is shown in which the body is housed and the sides other than the bent side are heat-sealed and sealed.
[0010]
And since an electrical storage element will generate | occur | produce heat | fever when charging / discharging repeats, from a viewpoint of cooling property, a pair of electrical storage element accommodating part is formed, and an electrical storage element is in the space formed in this pair of electrical storage element accommodating part. The structure which accommodates is preferable.
[0011]
Production of a laminate film having an electricity storage element accommodating portion (hereinafter referred to as an electricity storage element case) can be performed by subjecting the laminate film to processing such as drawing, vacuum forming, and pressure forming.
[0012]
At the time of processing to form the plurality of power storage element accommodation portions on the laminate film, the portion of the laminate film between the plurality of power storage element accommodation portions is pulled toward the storage element accommodation portion facing each other. For this reason, there existed a problem that a tear and a pinhole were easy to generate | occur | produce in the part between these several electrical storage element accommodating parts.
[0013]
[Problems to be solved by the invention]
The present invention has been made in view of the above circumstances, and manufacture of a storage element case capable of manufacturing a storage element case without tearing or pinholes occurring between portions of a plurality of storage element accommodation portions It is an object to provide a method.
[0014]
[Means for Solving the Problems]
As a result of repeated studies to solve the above problems, the present inventor has manufactured a power storage element housing portion by drawing processing in a state where slack is provided between portions serving as a plurality of power storage element housing portions. Has found that the above problems can be solved.
[0015]
That is, the method for manufacturing a case for a storage element according to the present invention is a method for manufacturing a case for a storage element in which a case for storage element having at least two storage element accommodating portions is manufactured by simultaneously drawing at least two places on a film. The film is characterized in that the film is subjected to a drawing process in a state in which a slack is imparted to a portion between at least two portions serving as the electricity storage element accommodating portion.
[0016]
In the method for manufacturing a case for a storage element according to the present invention, since drawing is performed at a plurality of locations in a state where sagging is applied, the sagging is formed even when the film is pulled in the opposite direction during processing. The film flows into the electricity storage element accommodating portion. As a result, the case for a storage element manufactured by the manufacturing method of the present invention is not torn or pinholes.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
The method for manufacturing a case for a storage element according to the present invention is a method for manufacturing a case for a storage element having at least two storage element accommodating portions by simultaneously drawing at least two places on a film. That is, by simultaneously drawing at least two places on the film, it is possible to manufacture a case for a storage element having at least two storage element accommodation portions at a time.
[0018]
In the method for manufacturing a case for a storage element according to the present invention, the drawing process is performed in a state in which a sag is applied to a portion between at least two places where the film serves as a storage element accommodating portion. That is, in the manufacturing method of the present invention, since the drawing is performed in a state in which the film is slack, even if the film is pulled in the opposite direction at the time of processing, the film that has formed this slack is the power storage element. It begins to flow into the accommodating part. As a result, the manufacturing method of the present invention does not generate tears or pinholes.
[0019]
The drawing process is a process of pressing the punch while the film is supported by a die and a wrinkle holding plate, and the wrinkle holding plate preferably has a ridge (bead). The die has a mold surface corresponding to the protrusion of the wrinkle holding plate. Since the wrinkle holding plate has a protrusion, when the film is supported by the wrinkle holding plate and the die, the film comes up from the wrinkle holding plate (drawing mold) in the vicinity of the protrusion. The lift of the film creates a gap between the wrinkle holding plate. That is, sagging is imparted to the film during drawing.
[0020]
In the manufacturing method of the present invention, in the drawing process, the punch is displaced from below to above in the vertical direction to press the film.
[0021]
In addition, by performing drawing using a wrinkle pressing plate provided with a ridge, a groove corresponding to the ridge is formed between the storage element housing portions of the case after processing. This groove can be used as a crease when the case is folded to manufacture the power storage element. By bending along the groove, the power storage element accommodating portion can be easily positioned.
[0022]
It is preferable that the protrusion is provided at the center of each of the plurality of punches. By providing a ridge at the center of each of the plurality of punches, the distance from the ridge to the punch becomes equal, the amount of film flowing in the direction of each power storage element accommodating portion at the time of drawing processing becomes uniform, and it is difficult to break, It is possible to easily perform the positioning of the electricity storage element accommodating portion when it is bent.
[0023]
In the manufacturing method of the present invention, the cross-sectional shape of the protrusion is not particularly limited. In other words, any cross-sectional shape that can provide the film with a slack that can secure the amount of film flowing in the direction of the electricity storage element housing portion during the drawing process may be used. This is because the flow amount of the film at the time of drawing changes because the processing depth of drawing differs depending on the size of the electricity storage element accommodated in the electricity storage element accommodation portion.
[0024]
The film is preferably a composite sheet in which a metal layer and a resin layer are laminated. When the film is made of a composite sheet, the water permeability and electrical insulation of the electricity storage element can be secured. Specifically, it has a structure in which resin layers are laminated on at least both surfaces of a metal layer. In this composite sheet, the metal layer ensures water resistance and the resin layer ensures insulation. More preferably, it is a composite sheet in which resin layers are laminated on at least both surfaces of a metal layer.
[0025]
In the composite sheet, the types of the metal and the resin constituting each of the metal layer and the resin layer are not particularly limited as long as the material can ensure water resistance and electrical insulation.
[0026]
The film is not particularly limited as long as it is a composite sheet, and a laminate sheet (laminate film) in which an electrode body is sealed in a conventional polymer battery can be used.
[0027]
The power storage element manufactured using the power storage element case manufactured by the manufacturing method of the present invention may be an element capable of holding electric power. For example, a capacitor and a battery can be mentioned.
[0028]
In the capacitor, the power storage element includes a pair of electrodes and an electrolytic solution. About a pair of electrode and electrolyte solution, it does not specifically limit and a conventionally well-known member can be used.
[0029]
Further, in the battery, the power storage element is a member having positive and negative electrodes and an electrolytic solution. The positive and negative electrodes and the electrolytic solution are not particularly limited, and conventionally known materials can be used.
[0030]
The case for the storage element manufactured by the manufacturing method of the present invention is folded in a state in which the storage element is arranged in the storage element housing part, and the peripheral part of the peripheral part of the storage element other than the bent side is sealed, A power storage element in which the power storage element is sealed can be manufactured. Moreover, it is preferable to seal the storage element melting case by heat sealing.
[0031]
It is preferable that the interval between a pair of adjacent power storage element accommodating portions that accommodate the same power storage element when bent is short. By reducing the distance between the pair of power storage element accommodating portions, the amount of film used is reduced, and the material cost can be reduced. Further, even if the electrolyte contained in the electricity storage element enters a bent portion that is not welded, since the bent portion is short, the amount of electric field liquid that degrades the performance of the electricity storage element does not come out of the electricity storage element housing portion. That is, there is an effect that the price of the power storage performance of the power storage element can be suppressed.
[0032]
In the method for manufacturing a case for a storage element according to the present invention, since the drawing process is performed in a state where a sag is imparted, the film forming the sag is stored in the film even if the film is pulled in the opposite direction during processing. It flows into the element accommodating part. As a result, the manufacturing method of the present invention does not generate tears or pinholes.
[0033]
【Example】
Hereinafter, the present invention will be described using examples.
[0034]
As an example of the present invention, a lithium battery case was manufactured.
[0035]
(Example)
As a battery case material, a laminate film having a thickness of 110 μm was cut into a size of 210 × 290 mm in length × width. This laminate film has a structure in which a nylon layer having a thickness of 30 μm is formed on the surface of an aluminum layer having a thickness of 40 μm and a polypropylene (PP) layer having a thickness of 40 μm is formed on the back surface. A cross section of the laminate film is shown in FIG.
[0036]
Subsequently, the laminate film was drawn using the mold shown in FIG.
[0037]
The mold shown in FIG. 2 is arranged so as to face the pressing surfaces of the two punches 2, 2 that move up and down in the vertical direction and whose pressing surface is formed upward, and the two punches 2, 2. And a die 3 having a mold surface corresponding to the pressing surface of the punches 2 and 2 and a wrinkle holding plate 4 that holds the two punches 2 and 2 and supports the laminate film 1 between the die 3. Have. The interval between the punches 2 and 2 was 10 mm.
[0038]
Further, a bead 5 is provided on the surface of the wrinkle pressing plate 4 and in the center between the two dies 2 and 2. The bead 5 has a substantially triangular cross-sectional shape with a base of 4 mm and a height of 3 mm.
[0039]
In the drawing process, first, the laminate film 1 is formed on the wrinkle holding plate 4 with the P.P. P. The layer was placed on the mold in a state of facing the wrinkle holding plate 4. The laminated film 1 arranged was arranged in a state where the center portion was raised by the bead 5.
[0040]
Subsequently, the die 3 was displaced vertically downward, and the laminate film 1 was supported between the die 3 and the wrinkle holding plate 4 so that no wrinkle was generated. At this time, the slack of the laminate film 1 generated by the beads 5 remained.
[0041]
Thereafter, the die 3 was further displaced vertically downward. Due to the displacement of the die 3, the pressing surfaces of the two punches 2 and 2 were pushed into the die 3. At this time, the wrinkle pressing plate 4 was displaced downward together with the die 3. When the punches 2 and 2 were pushed into the inside of the die 3, a concave battery element housing portion was formed on the laminate film 1. The displacement of the die 3 was 10 mm, and the depth of the battery element housing portion formed by the punches 2 and 2 was also 10 mm. A state in which the punches 2 and 2 press the laminate film 1 is shown in FIG.
[0042]
The lithium battery case of the example could be manufactured by the above drawing process. The produced lithium battery case is shown in FIG.
[0043]
The manufactured lithium battery case has a shape having a groove 11 formed by the bead 5 and battery element accommodating portions 12 and 12 formed symmetrically in the groove 11.
[0044]
In the manufactured lithium battery case of the example, no tear or pinhole was observed in the vicinity of the groove 11 formed by the bead 5. That is, it can be seen that the laminate film constituting the lithium battery case has a sufficient thickness even in the vicinity of the groove 11.
[0045]
(Manufacture of batteries)
A lithium secondary battery was manufactured using the lithium battery case manufactured in the examples.
[0046]
First, a positive electrode active material made of LiNiO ₂ , a conductive agent made of carbon, and a binder made of polyvinylidene fluoride (PVDF) are dissolved in an N-methyl-2-pyrrolidone (NMP) solution, and the positive electrode active material A paste was prepared. This paste was applied to both surfaces of a positive electrode current collector made of aluminum foil with a comma coater. Then, the electrode was passed through a roll press machine to apply a load, and a positive electrode plate with improved electrode density was produced.
[0047]
This positive electrode plate was cut into a predetermined size, and a sheet-like positive electrode was produced by scraping off the electrode mixture at a portion to be a lead tab weld for extracting current.
[0048]
Subsequently, a negative electrode active material made of graphite and a binder made of PVDF were dissolved in an NMP solution to prepare a negative electrode active material paste. This paste was applied to both surfaces of a negative electrode current collector made of copper foil using a comma coater in the same manner as the positive electrode. Thereafter, the copper foil coated with this paste was passed through a roll press to apply a load, and a negative electrode plate having an increased electrode density was produced.
[0049]
This negative electrode plate was cut into a predetermined size, and a sheet-like negative electrode was produced by scraping off the electrode mixture at a portion to be a lead tab weld for extracting current.
[0050]
The sheet-like positive electrode and the sheet-like negative electrode obtained above were wound into a flat shape with a separator made of microporous polypropylene having a thickness of 25 μm, to form a flat wound electrode body. Then, the electrode tab was fused to the uncoated portion where the sheet-like positive electrode and negative electrode electrode mixture of the flat wound electrode body was scraped. The electrode tab fused to the positive electrode and the negative electrode was attached in a state of protruding in the same direction.
[0051]
Further, the LiPF ₆ as the electrolyte, a solvent prepared by mixing an equal volume ratio ethylene carbonate (EC) and diethyl carbonate (DEC), an electrolyte solution was prepared by dissolving at a rate of 1mol / liter.
[0052]
Subsequently, the produced flat wound electrode body 6 was housed in the battery element housing portion of the lithium battery case described above. The flat wound electrode body was accommodated by bending the lithium battery case with a groove formed by a bead in a state where the flat wound electrode body was disposed at a position corresponding to the battery element accommodating portion. At this time, the electrode tabs 61 and 61 attached to the flat wound electrode body 6 were exposed from the case for a lithium battery in which an end portion not joined to the flat wound electrode body was bent. FIG. 4 shows how the flat wound electrode body 6 is accommodated in a lithium battery case.
[0053]
Then, in the state where the flat wound electrode body is accommodated, the electrolyte is poured into the battery element accommodating portion, and the peripheral portion of the battery element accommodating portion other than the side where the groove of the lithium battery case is formed is formed. The electrode body and the electrolytic solution were sealed by welding.
[0054]
The lithium secondary battery was able to be manufactured by the above procedure.
[0055]
In the manufactured lithium secondary battery, no tear or pinhole was observed in the vicinity of the groove of the lithium battery case.
[0056]
(Other forms of embodiment)
Further, a die in which the cross-sectional shape of the bead is a triangular shape, and a concave groove having an inner peripheral surface substantially coincident with the outer peripheral shape of the bead may be used in a corresponding portion of the die facing the bead.
[0057]
Even in the embodiment having the bead and the groove, no tear or pinhole was observed in the laminated film after molding.
[0058]
Further, in the laminated film molded in this form, a clear broken line is formed at the portion pressed by the bead.
[0059]
This broken line facilitates bending and positioning when forming a lithium secondary battery. That is, in this embodiment, not only drawing can be performed, but also productivity in assembling a lithium secondary battery is improved.
[0060]
In the present embodiment, the laminate film is used for explanation, but a single layer film can be used as long as it is a material that can ensure water resistance and insulation.
[0061]
【The invention's effect】
In the method for manufacturing a case for a storage element according to the present invention, since the drawing process is performed in a state where a slack is imparted, even if the laminate film is pulled in the opposite direction at the time of processing, the laminate film that has formed this slack Flows into the storage element accommodating portion. As a result, the case for a storage element manufactured by the manufacturing method of the present invention is not torn or pinholes.
[Brief description of the drawings]
FIG. 1 is a view showing a cross section of a laminate film.
FIG. 2 is a view showing a configuration of a mold.
FIG. 3 is a view showing a state where a punch of a mold presses a laminate film.
FIG. 4 is a view showing a case for a lithium battery according to an example.
FIG. 5 is a view showing a state in which a flat wound electrode body is housed in a lithium battery case.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Laminate film 11 ... Groove 12 ... Battery element accommodating part 2 ... Punch 3 ... Die 4 ... Wrinkle pressing board 5 ... Bead 6 ... Flat wound type electrode body 61 ... Electrode tab

Claims (3)

A method for producing a case for a storage element, wherein a drawing process is simultaneously performed on at least two places of a film to manufacture a case for a storage element having at least two storage element accommodation parts,
The method for producing a case for a power storage element, wherein the film is subjected to the drawing process in a state in which a slack is imparted to a portion between at least two portions serving as the power storage element accommodating portion. A machining for pressing a plurality of punches in a state where the drawing is to support the film at the die and the blank holder plate, power storage according to claim 1, wherein said blank holder plate has a ridge between a plurality of the punches A method for manufacturing a case for an element.   The method for manufacturing a case for a storage element according to claim 2, wherein the protrusion is provided at the center between each of the plurality of punches.

Images