JP2007073322A - Method of sealing battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of sealing a battery hardly forming burrs outside a battery when sealing an opening of a frame body by an enveloping film, and to provide the frame body capable of realizing such a sealing method. <P>SOLUTION: The sealing method comprises a process of positioning the enveloping film 12 against the frame body 14 so as to cover the opening 22 of the frame body 14 by the enveloping film 12, and a process of adhering the enveloping film 12 to an adhering face 16 formed on peripheral edge of the opening 22 of the frame body 14. On this sealing method, before sealing, a convex part 20 and a recessed part 18 in proximity to each other are formed at least on a part of the adhering face 16 of the frame body 14, and cubic volume of the recessed part 18 is larger than the volume of protrusion of the convex part 20. At the above sealing process, at least the convex part 20 on the adhering face 16 of the frame body is heated and fused. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a battery sealing method. Specifically, the present invention relates to a battery sealing method in which an opening of a frame body that houses a power generation element is sealed with an exterior film.

A resin frame is used as a battery package. The resin frame is strong against external impact and excellent in handleability, and is lightweight. For this reason, in order to protect a power generation element suitably and to suppress an increase in the weight of the battery, a resin frame is widely used.
The power generation element housed in the frame is vulnerable to moisture, and the performance decreases when it comes into contact with moisture. For this reason, in this type of battery, the opening of the frame is sealed with an exterior film to protect the power generation element from moisture. As an example of a battery in which a resin frame is used, a battery described in Patent Document 1 can be given.

JP-A-6-338304

  In such a battery, in order to seal the opening of the frame body with the exterior film, the welding surface formed on the periphery of the opening of the frame body and the exterior film are welded. During the welding process, in order to improve the sealing state (welding strength) between the exterior film and the frame, the exterior film is pressed against the welding surface of the frame by a heat bar (welding bar) and heated while applying a load to both. When the resin on the welding surface is melted or softened while a load is applied, a part of the melted or softened resin is pushed out of the battery. When the extruded resin is solidified, so-called “burrs” are generated. When a burr | flash is formed in the outer side of a battery, problems, such as the beauty | look of the battery as a product being impaired, will arise.

  An object of the present invention is to provide a battery sealing method in which burrs are hardly formed on the outside of a battery when an opening of a frame is sealed with an exterior film. Another object of the present invention is to provide a frame that can realize such a sealing method.

  The present invention is a battery sealing method in which an opening of a frame body that houses a power generation element is sealed with an exterior film. In this sealing method, the step of positioning the exterior film with respect to the frame so that the opening of the frame is covered with the exterior film, and the welding surface formed on the periphery of the opening of the frame and the exterior film are welded The process of carrying out. In this sealing method, before welding, a convex portion and a concave portion are formed in close proximity to at least a part of the welding surface of the frame, and the concave portion has a hollow volume that is greater than the protruding volume of the convex portion. . And in the said welding process, at least the said convex part is heat-melted among the welding surfaces of a frame, It is characterized by the above-mentioned.

The sealing method described above seals the opening of the frame body by welding an exterior film to the welding surface of the frame body on which convex portions and concave portions are formed. The welding process is performed in a form in which the welding surface of the frame and the exterior film are heat-bonded. During the welding process, the resin forming the convex portion melts, and the molten resin flows into the concave portion and solidifies. Since the concave portion has a hollow volume that is equal to or larger than the protruding volume of the convex portion, the resin flowing from the convex portion can be easily received. For this reason, when the frame and the exterior film are welded, the molten or softened resin is difficult to protrude to the outside of the battery. Since the molten or softened resin is difficult to protrude outside the battery, the formation of burrs can be suppressed.
According to the present sealing method, the formation of burrs is suppressed when the frame and the exterior film are welded, and a battery having an excellent aesthetic appearance can be provided.

In this sealing method, in the positioning step, the convex portion is formed in an annular shape along the circumferential direction of the peripheral edge of the opening, and the concave portion is also formed in an annular shape along the peripheral direction of the peripheral edge of the opening. It is preferable to adopt it.
According to such a configuration, the outer film and the frame can be welded uniformly over the entire circumference by being annularly provided in the circumferential direction of the opening in a state where the convex portion and the concave portion are close to each other. Have

The present invention also provides a frame for a battery that houses a power generation element.
The frame of the present invention has an opening sealed by an exterior film, a welding surface formed at the periphery of the opening, and a convex portion and a concave portion formed on at least a part of the welding surface. Yes. The convex portion and the concave portion are formed close to each other, and the concave portion has a hollow volume that is greater than or equal to the protruding volume of the convex portion.
Since the concave volume of the concave portion provided on the welding surface has a size equal to or larger than the protruding volume of the convex portion, it can be accommodated in the concave portion even if the resin on the convex portion is completely melted. When the convex resin melted or softened during the welding process is accommodated in the concave, the melted or softened resin hardly protrudes outside the battery. Therefore, when the frame of the present invention is used, burrs are hardly formed on the outside of the battery.

In the frame of the present invention, the convex portion is preferably formed along the circumferential direction of the peripheral edge of the opening, and the concave portion is preferably provided along the circumferential direction of the peripheral edge of the opening.
When the battery is sealed using the frame body having such a configuration, the formation of burrs on the outside of the battery can be effectively suppressed.

Note that the “battery” in this specification refers to a battery that can extract electric energy and is not limited to the principle of power storage. Secondary batteries such as lithium secondary batteries, electric double layer capacitors, and the like are also included in the battery referred to here. An assembled battery obtained by joining a plurality of these power generation elements is also included in the “battery” referred to herein.
The “frame” in the present specification refers to a member that can physically store the power generation element, and there is no limitation on the shape thereof.

  The sealing method of the present invention can be applied to a battery having a structure sealed with a package made of an exterior film and a resin frame. According to the sealing method of the present invention, generation of burrs on the outside of the battery can be suppressed.

The main features of the embodiments described in detail below are listed first.
(Mode 1) The battery is a lithium secondary battery.
(Mode 2) The exterior film is a laminate film having a three-layer structure including an outer surface layer made of a high melting point resin material, a barrier layer made of a metal material, and a welded resin layer made of a thermoplastic resin material.
(Mode 3) The frame is made of polypropylene.
(Embodiment 4) The frame body is a flat box shape with one open surface, and is composed of one bottom plate and four side plates.
(Form 5) The cross-sectional shape of the convex part formed in the welding surface of the frame is a substantially square shape. The cross-sectional shape of the recess formed on the welding surface of the frame body is also substantially rectangular.
(Form 6) The cross-sectional shape of the convex part formed in the welding surface of the frame is a substantially triangle. The cross-sectional shape of the recess formed on the welding surface of the frame body is also substantially triangular.
(Mode 7) On the welding surface of the frame body, a plurality of convex portions are formed in a regularly aligned state. The shape of each convex part is a substantially cylindrical shape (conical frustum shape). The concave portion is provided around the convex portion. Specifically, when the welding surface of the frame is viewed from above, the concave portion is formed in a ring shape that is substantially concentric with the convex portion.

  Hereinafter, some examples of a battery to which a sealing method and a frame of the present invention are applied will be described with reference to the drawings.

<First Example>
First, based on FIGS. 1-4, the structure of the lithium secondary battery 10 of a present Example is demonstrated. FIG. 1 is an exploded perspective view of the battery 10 and shows a state before the opening 22 of the frame body 14 is sealed with the exterior film 12. 2 is a cross-sectional view taken along the line II-II in FIG. 1 and shows a cross-sectional shape of the side plate 14a of the frame body 14. FIG. 3 is a schematic diagram for explaining a welding process between the frame body 14 and the exterior film 12. FIG. 4 shows the welding surface 16 after the welding process. A broken line portion in FIG. 4 indicates the exterior film 12 and the concave portion 18 of the frame body 14 before the welding process.

A rough configuration of the battery 10 according to the present embodiment will be described.
As shown in FIG. 1, the battery 10 of the present example accommodates a flat spiral-shaped wound electrode body 26 in a flat box-shaped frame body 14 whose upper surface is open, and the exterior film 12 covers the frame body 14. This is a lithium secondary battery in which the opening 22 is sealed.

The electrode body 26 is a wound electrode body that is formed by laminating a positive electrode sheet (positive electrode) and a negative electrode sheet (negative electrode) with a separator interposed therebetween and winding it into a flat spiral shape. The electrode body 26 constitutes a power generation element of the lithium secondary battery 10 together with the electrolyte.
The positive electrode sheet has an aluminum current collector foil, and a positive electrode active material layer is provided on both front and back surfaces of the current collector foil. The positive electrode sheet is connected to the positive electrode lead terminal 24. The positive electrode lead terminal 24 is made of an aluminum plate. The positive electrode lead terminal 24 is fixed to the frame body 14.
The negative electrode sheet has a copper current collector foil, and negative electrode active material layers are provided on both front and back surfaces of the current collector foil. The negative electrode sheet is connected to the negative electrode lead terminal 28. The negative electrode lead terminal 28 is made of a copper plate material. The negative electrode lead terminal 28 is fixed to the frame body 14.
The separator is a porous polyolefin sheet. The separator is infiltrated with electrolyte.
The electrolyte constitutes the power generation element of the battery as described above. As the electrolyte, a conventionally known liquid non-aqueous electrolyte or gel polymer electrolyte for a lithium secondary battery can be used. For example, an electrolyte obtained by dissolving lithium hexafluoride (LiPF ₆ ) as a lithium salt in a mixed solvent of diethyl carbonate (DEC) and ethylene carbonate (EC) (for example, a mixed solvent having a mass ratio of DEC: EC of 7: 3). Can be used.

Next, the frame body 14 according to the present embodiment will be described.
The frame body 14 constituting the battery 10 according to the present embodiment is formed of a polypropylene resin that is a thermoplastic resin. Since the polypropylene resin is a resin having excellent adhesion to the laminate film constituting the exterior film 12 and having rigidity, it can be suitably used as a frame material constituting the battery package.
As shown in FIGS. 1 and 2, the frame 14 has a flat box shape composed of one rectangular bottom plate 14c and four side plates 14a and 14b erected on the four sides of the bottom plate 14c. Have. The frame body 14 is open at a surface facing the bottom plate 14 c and has an opening 22. The four side plates 14 a and 14 b surround the opening 22 and form the periphery of the opening 22. An inner side of the frame body 14 (that is, an internal space formed by the bottom plate 14c and the four side plates 14a and 14b) is a space (hereinafter referred to as “accommodating portion 15”) that accommodates the power generation element. The electrode body 26 is accommodated in the accommodating portion 15 through the opening 22. By housing the electrode body 26 in the housing portion 15 of the frame body 14, the electrode body 26 is physically protected, and deformation, breakage, and the like due to stress from the outside can be prevented.
The exterior film 12 is welded to the upper surfaces of the side plates 14a and 14b. That is, the upper surfaces of the side plates 14 a and 14 b are welded surfaces 16 that are welded to the exterior film 12. As shown in FIG. 1, a convex portion 20 is annularly provided along the circumferential direction of the opening 22 on the welding surface 16, and a concave portion 18 is annularly provided just outside the convex portion 20. As shown in the cross-sectional shape of FIG. 2, the convex portion 20 has a substantially square cross-sectional shape. The recess 18 also has a substantially square cross-sectional shape. The convex portion 20 and the concave portion 18 are provided adjacent to each other without a gap. The convex portion 20 and the concave portion 18 are provided such that the recess volume of the concave portion 18 is equal to or larger than the protruding volume of the convex portion 20.

  Although not shown, the frame body 14 is formed with an injection hole for injecting an electrolyte. After the electrode body 26 is accommodated in the accommodating portion 15 of the frame body 14 and the exterior film 12 and the frame body 14 are welded, a predetermined electrolyte can be injected into the accommodating portion 15 from the injection hole. Specifically, an electrolyte injection needle is inserted into the injection hole to inject the electrolyte into the housing portion 15. After the injection, the injection hole is sealed again by pulling out the injection needle. The electrolyte injection hole is configured by disposing an elastic member at a predetermined portion of the frame body 14.

  Next, the exterior film 12 which comprises the package of the battery 10 with the frame 14 is demonstrated. As the exterior film 12, a conventionally used laminate film can be used. In this embodiment, a laminate film having an outer surface layer 32 made of nylon, a barrier layer 34 made of aluminum, and a welded resin layer 36 made of polypropylene is employed. The exterior film 12 is cut out in substantially the same shape as the surface having the opening 22 of the frame body 14. The battery 10 is sealed by welding and fusing the resin of the welding resin layer 36 of the exterior film 12 and the resin of the welding surface 16 of the frame body 14.

  Next, a method for sealing the battery 10 will be described. First, the electrode body 26 is accommodated in the accommodating portion 15 of the frame body 14 as shown in FIG. Specifically, the electrode body 26 is accommodated in the accommodating portion 15 through the opening 22 of the frame body 14, and the positive electrode lead terminal 24 and the negative electrode lead terminal 28 are electrically connected to the positive electrode sheet and the negative electrode sheet of the electrode body 26, respectively.

  Next, the exterior film 12 is superimposed on the frame body 14 from above the frame body 14 (in the direction of the arrow shown in FIG. 1) to cover the opening 22 of the frame body 14, and in this state, the welding surface 16 of the frame body 14 and the exterior The film 12 is heat-pressed (precisely, the welded resin layer 36 of the frame 14 and the exterior film 12 is welded). As a means for welding the exterior film 12 and the frame body 14, a special method is not required and it can be performed by a general heating means. In the present embodiment, a heat press machine (not shown) is used and a method of heat-pressing with a hot plate (heat bar) 30 is employed.

The welding process will be described in detail with reference to FIGS.
On the welding surface 16 of the frame body 14, as described above, the convex portion 20 and the concave portion 18 are formed in an annular shape along the circumferential direction of the opening 22. As shown in FIG. 3, when the frame body 14 and the exterior film 12 are overlapped, the exterior film 12 first comes into contact with the convex portion 20 on the welding surface 16. When the hot plate 30 is moved from the top of the outer film 12 in the direction of the arrow X and pressed against the outer film 12, the heat from the hot plate 30 flows to the convex portion 20 through the outer film 12, and the frame from the convex portion 20 to the frame. It flows to each part of the body 14. For this reason, the convex part 20 of the frame 14 is heated intensively, and resin in the convex part 20 melts preferentially. The molten resin (the resin melted out of the convex portion 20) flows around the convex portion 20 (outside and inside of the frame body 14). The resin that has flowed to the outside of the frame body 14 (in the direction of arrow Y) flows into the recess 18 and fills the recess 18. When the resin forming the convex portion 20 is completely melted, the entire weld surface 16 and the weld resin layer 36 of the exterior film 12 come into contact with each other, and the weld resin layer 36 of the exterior film 12 and the weld surface 16 of the frame 14 are in contact with each other. The whole is fused to complete the welding process (see FIG. 4).
In addition, while performing the welding process of the exterior film 12 and the frame 14, the load which presses the hot plate 30 against the frame 14 can be made substantially constant. If the load acting on the frame body 14 from the hot plate 30 is substantially constant, the load from the hot plate 30 is received by the convex portion 20 of the frame body 14 at the initial stage of welding, so that a large pressure is applied to the convex portion 20 and the exterior film 12. Act. On the other hand, in the latter stage of welding, since the load from the hot plate 30 is received by the whole welding surface 16 of the frame body 14, the pressure which acts between the welding surface 16 of the frame body 14 and the exterior film 12 becomes small.
After the frame 14 and the exterior film 12 are welded, an electrolyte is injected from the electrolyte injection port, and the lithium secondary battery 10 according to the present embodiment is completed.

In the sealing method of the present embodiment, first, the convex portion 20 of the frame body 14 is melted and the frame body 14 and the exterior film 12 are partially welded, and then the entire welding surface 16 of the frame body 14 and the exterior film. 12 is welded. When the convex portion 20 of the frame body 14 is melted, the load from the hot plate 30 acts only on the convex portion 20 of the frame body 14, so that the convex portion 20 and the exterior film 12 are pressurized with a high pressure. For this reason, the welding part of both can have fixed welding intensity | strength and airtightness only by the convex part 20 of the frame 14 fuse | melting, and only the frame 14 and the exterior film 12 weld. On the other hand, when welding the whole welding surface 16 and the exterior film 12, the load from the hot plate 30 acts on the whole welding surface 16, and therefore the pressure acting between the frame 14 and the exterior film 12 is low. Thus, the occurrence of burrs on the outside of the battery 10 is suppressed.
Further, the resin of the convex portion 20 is pressurized and melted at a high pressure, but the resin that flows to the outside (that is, the resin that causes burrs) flows into the concave portion 18 and exceeds the concave portion 20. To prevent it from flowing outward. In addition, the concave portion 18 can accept not only the resin of the convex portion 20 but also the resin constituting the welding resin layer 36 of the exterior film 12 and the welding surface of the frame body 14. For this reason, it is prevented that the welding resin layer 36 of the exterior film 12 and the resin of the convex part 20 of the frame body 14 that melted during the welding process fill the recesses of the concave part 18 and flow to the outside of the frame body 14. It is difficult to form burrs on the outside of the battery 10.
In addition, when burrs are formed on the outside of the battery, a gap is likely to be formed between the frame body and the exterior film, and moisture may enter the inside through the gap and the battery performance may be reduced. In the sealing method of the present embodiment, since burrs are hardly formed on the outside of the battery 10, moisture intrusion into the frame body 14 due to the generation of burrs is prevented, and the performance of the battery 10 is maintained well over a long period of time. can do.
In the sealing method of the present embodiment, as described above, first, the convex portion 20 of the frame body 14 is melted to partially weld the frame body 14 and the exterior film 12. According to this sealing method, at least the portion where the convex portion 20 and the exterior film 12 abut is firmly welded, and the battery 10 is kept liquid-tight. In the battery 10 employing this sealing method, it is difficult for moisture to enter from the outside to the inside and for electrolyte to leak to the outside.
Furthermore, according to the sealing method of the present embodiment, the heat applied from the hot plate 30 during the welding process is difficult to diffuse to other parts of the frame body 14, and the convex portions 20 of the frame body 14 are intensively heated. . For this reason, excessive melting of the entire frame 14 is prevented during the welding process, and the time required for the welding process can be shortened. Further, since thermal diffusion to the electrode body 26 accommodated inside the frame body 14 is prevented during the welding process, there is an advantage that the separator of the electrode body 26 is hardly damaged during the welding process.

<Second Example>
The present embodiment has the same configuration as that of the first embodiment except that the shapes of the convex portion 120 and the concave portion 118 of the frame body 114 are different. In the following description, only differences from the first embodiment will be described, and descriptions of points that overlap with the first embodiment will be omitted.

FIG. 5 shows the shape of the welding surface 116 of the frame 114 according to the present embodiment (before the welding process). As shown in FIG. 5, the convex portion 120 of the frame body 114 has a substantially triangular cross-sectional shape, and the cross-sectional shape of the concave portion 118 also has a substantially triangular shape. The convex part 120 and the recessed part 118 are provided continuously without leaving a space like the frame body 14 according to the first embodiment. The convex portion 120 and the concave portion 118 are provided such that the concave volume of the concave portion 118 is equal to or larger than the protruding volume of the convex portion 120. The exterior film 12 has the same configuration as that of the first embodiment, and is used that is cut into substantially the same shape as the surface of the frame 114 having the opening 122.
To seal the opening 122 of the frame body 114 with the exterior film 12, the exterior film 12 and the frame body 114 are overlapped, and the hot plate 30 is moved in the direction of the arrow X from above the exterior film 12 to form the exterior film 12. By pressing, the welding surface 116 of the frame 114 and the exterior film 12 are heat-welded. When heated and welded, the resin constituting the convex portion 120 flows to the outside and the inside of the frame body 114, and the resin (arrow Y) that flows to the outside fills the concave portion 118. When the resin of the convex portion 120 is melted, the entire welding surface of the frame body 114 and the exterior film 12 are then welded.
Also by the sealing method of the second embodiment, the concave portion 118 can accept the resin constituting the convex portion 120 and also accepts the resin that constitutes the welded resin layer 36 of the exterior film 12. Can do. Therefore, even in the battery in which the sealing method of this embodiment is adopted, the resin melted at the time of the sealing work hardly protrudes to the outside, and the generation of burrs is suppressed.

Further, in the frame body 114 according to the present embodiment, the cross-sectional shape of the convex portion 120 and the concave portion 118 is substantially triangular, and constitutes an inclined surface in which the outer wall surface of the convex portion 120 and the inner wall surface of the concave portion 118 are continuous. For this reason, the resin melted from the convex portion 120 can smoothly flow into the concave portion 118. Therefore, the filling state of the resin flowing into the recess 118 from the protrusion 120 is good.
The heat applied from the hot plate 30 during the welding process concentrates on the convex portion 120 of the frame body 114. In particular, since the projecting portion 120 according to the present example has a substantially triangular cross-sectional shape, the contact area between the exterior film 12 and the projecting portion 120 is reduced in the initial stage of melting (at the start of melting, the contact is linear. To do). For this reason, at the time of the welding process, the resin of the convex part 120 melts rapidly, and the time of the welding process is shortened.
The sealing method of the second embodiment is welded while melting the convex portion 120 of the frame body 114 in the same manner as the sealing method of the first embodiment. According to this sealing method, at least a portion where the convex portion 120 is melted and welded to the exterior film 12 is firmly sealed because it is heated and melted in a state of being pressurized at a high pressure. Since the welding surface 116 and the exterior film 12 are welded without interruption, the battery is kept liquid-tight. A battery in which the present sealing method is adopted is also less likely to cause a problem that moisture enters the inside from the outside and a problem that the electrolyte leaks to the outside.
Further, the heat applied to the frame body 114 during the welding process is difficult to diffuse to other parts of the frame body 114. For this reason, there is an advantage that excessive melting of the entire frame 114 is prevented during the welding process. Furthermore, since heat diffusion to the electrode body accommodated in the frame body 114 is also prevented, there is an advantage that the separator of the electrode body is not easily damaged during the welding process.

<Third embodiment>
This embodiment has the same configuration as that of the first embodiment and the second embodiment, except that the configuration of the convex portion 220 and the concave portions 218a and 218b formed on the welding surface 216 of the frame body 214 is different. In the present embodiment, the description overlapping with the first embodiment and the second embodiment is omitted.

FIG. 6 shows a cross-sectional shape of the welding surface 216 of the frame body 214 according to the present embodiment (before the welding process). As shown in FIG. 6, the convex part 220 of the frame 214 has a substantially quadrangular cross-sectional shape. The concave portions 218 a and 218 b are formed on both sides of the convex portion 220. The cross-sectional shapes of the recesses 218a and 218b are also substantially rectangular. The recess depths of the recesses 218a and 218b are smaller than the protrusion height of the protrusion 220, but the sum of the recess volumes of the recesses 218a and 218b is equal to or greater than the protrusion volume of the protrusion 220. . The convex portion 220 and the concave portions 218a and 218b are provided without being spaced from each other. The exterior film 12 is cut out in substantially the same shape as the surface of the frame 214 having the opening 222.
In order to seal the opening 222 of the frame body 214 with the exterior film 12, the exterior film 12 and the frame body 214 are overlapped, and the hot plate 30 is moved in the direction of the arrow X from above the exterior film 12 to form the exterior film 12. By pressing, the welding surface 216 of the frame body 214 and the exterior film 12 are heat-welded. When heated and welded, the resin constituting the convex portion 220 flows inside (arrow Y1) and outside (arrow Y2) of the frame body 214 and fills the concave portions 218a and 218b. In this example, the resin of the convex part 220 that melted during the welding process is received in the concave parts 218a and 218b provided on both sides of the convex part 220, and the resin that constitutes the welded resin layer 36 of the exterior film 12, Received in the recesses 218a, 218b. Therefore, it is difficult for the molten resin to protrude from the battery. Also according to this example, it is possible to suppress the formation of burrs on the outside of the battery. Further, the concave portion 218b is formed on the inner side (accommodating portion 215 side) of the convex portion 220 on the welding surface 216. The resin that has melted during the welding process has an advantage that it does not easily protrude into the inside of the frame body 214 (side of the housing portion).
In the present embodiment, as in the first embodiment, first, the convex portion 220 of the frame body 214 is welded while melting. For this reason, at least a portion where the convex portion 220 is melted and welded to the exterior film 12 can have sufficient welding strength and airtightness. Since the convex portion 220 and the concave portions 218a and 218b are formed over the entire circumference of the welding surface 216 (periphery of the opening 222), the welding surface 216 and the exterior film 12 are welded along the peripheral edge of the opening 222 without interruption. As a result, the battery sealed by the sealing method of the present embodiment is kept liquid-tight, and it is difficult to cause a problem that moisture enters the inside and a problem that the electrolyte leaks to the outside.
Also in this example, the formation of burrs is suitably suppressed. Furthermore, the heat applied from the hot plate 30 during the welding process is difficult to diffuse to other parts of the frame body 214 and concentrates on the convex portions 220 of the frame body 214. For this reason, there is an advantage that excessive melting of the entire frame body 214 is prevented during the welding process. Further, since heat diffusion to the electrode body accommodated in the frame body 214 is also prevented, there is an advantage that the separator of the electrode body is not easily damaged during the welding process.

<Fourth embodiment>
This embodiment has the same configuration as that of the first to third embodiments, except that the configuration of the projections 320 and the recesses 318 formed on the welding surface 316 of the frame 314 is different. In the present embodiment, the description overlapping with the first to third embodiments is omitted. FIG. 7 is a plan view of the welding surface 316 of the frame body 314 according to the present embodiment, and FIG. 8 is a sectional view taken along line VIII-VIII in FIG.

As shown in FIG. 7, a plurality of substantially cylindrical convex portions 320 are formed on the welding surface 316 of the frame 314, and a concave portion 318 is formed around each convex portion 320. That is, the welding surface 316 is provided with a plurality of convex concave portions 321 formed by a pair of convex portions 320 and concave portions 318. The convex recess 321 is regularly provided over the entire welding surface 316. As shown in FIG. 8, the convex part 320 has a substantially trapezoidal cross-sectional shape. The cross section of the recess 318 is also provided to be substantially trapezoidal. The concave depth of the concave portion 318 is smaller than the protruding height of the convex portion 320, but the concave volume of the concave portion 318 is configured to be equal to or larger than the protruding volume of the convex portion 320. The exterior film 12 is cut out in substantially the same shape as the surface having the opening 322 of the frame body 314 in the same manner as the exterior film 12 of the first embodiment.
In order to seal the opening 322 of the frame body 314 with the exterior film 12, the exterior film 12 and the frame body 314 are overlapped, and the both sides are bonded by the hot plate 30 in a state where the welding surface 316 of the frame body and the exterior film 12 are overlapped. Heat welding. In this embodiment, the resin of the convex part 320 of the frame body 314 melted during the welding process is received by the concave part 318. Further, the resin constituting the welded resin layer 36 of the exterior film 12 is also received in the recess 318. For this reason, it can suppress that the resin fuse | melted at the time of a welding process protrudes from a welding area | region. Therefore, even in the battery in which the sealing method of this embodiment is adopted, the formation of burrs is preferably suppressed.
Furthermore, the heat applied from the hot plate 30 during the welding process is concentrated on the plurality of convex portions 320 instead of the entire welding surface 316. Since heat diffusion to the electrode body accommodated inside the frame body 314 is prevented, the advantage that the separator of the electrode body is not easily damaged during the welding process, and excessive melting of the frame body 314 during the welding process is prevented. Has the advantage.

  The embodiment described above can be variously changed, modified, modified, and / or improved. Various changes can be made without departing from the spirit and scope of the invention. Accordingly, the apparatus and method according to the present invention are intended to include all known or later developed changes, modifications, variations and / or improvements.

For example, the shape of the convex part and recessed part formed in a frame is not specifically limited. As shown in the above embodiment, in addition to a form having a substantially square cross-sectional shape or a form having a substantially triangular cross-sectional shape, a form having a substantially semicircular cross-sectional shape can be employed.
Moreover, the position and number of the convex part and recessed part which are formed in a welding surface can be suitably set from the shape and structure of a welding surface. For example, when the welding surface of the frame is viewed in plan, the convex portions and the concave portions may be provided in a lattice shape. Moreover, when the welding surface of a frame is planarly viewed, the substantially square convex part and recessed part may be provided alternately by the checkered pattern shape.
Moreover, in the said Example, although the single battery which accommodates one electrode body in one frame body was illustrated, the sealing method of this invention is applied to the assembled battery which accommodates several electrode bodies in one frame body. can do.

  The electrode body accommodated in the frame body is not particularly limited as long as it is a power generation element capable of storing and discharging predetermined power. There is no restriction | limiting in particular in the shape and size of an electrode body, It can comprise in a desired form and size. Typical power generation elements include various forms of primary batteries (eg, lithium primary batteries, manganese batteries), secondary batteries (eg, lithium secondary batteries, nickel metal hydride batteries), or capacitors (eg, electric double layer capacitors). be able to.

  The size or shape of the frame body or electrode body housing portion of the present invention can be appropriately changed depending on the type, size, shape, etc. of the electrode body to be housed. A frame body made of a material that is an impact resistant material and is resistant to a reaction product resulting from the use of an electrolyte or an electrode body constituting a storage element to be accommodated (held) is preferable. Typically, it is preferable to select an insulating material. For example, polyolefin resins such as polyethylene and polypropylene, ethylene-propylene-diene copolymer (EPDM) and the like are preferably selected. Further, PPS (polyphenylene sulfide resin), polystyrene resin, polyimide resin, polyamideimide resin, fluorine resin, PEEK (polyether ether ketone resin), PES (polyether sulfone resin), or the like may be used. The frame may be composed of a single resin material selected from these resins, or may be composed of a material in which two or more kinds of resins are mixed.

  The exterior film can be used without particular limitation as long as it constitutes a package of this type of battery. Typically, an outer surface (protective) layer composed of a high melting point resin (for example, polyethylene terephthalate (PET), polytetrafluoroethylene (PTFE), polyamide (PA) -based resin) and a metal foil (for example, aluminum, steel) And a heat-fusible resin (a resin having a relatively low melting point, such as ethylene vinyl acetate, or an olefin resin such as polyethylene or polypropylene). A laminate film having a three-layer structure with an adhesive layer can be preferably used. Such a three-layer structure laminate film can be welded to the frame body by using an appropriate thermocompression bonding means (for example, a heat press machine).

  The technical elements described in the present specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology illustrated in the present specification or the drawings achieves a plurality of objects at the same time, and has technical utility by achieving one of the objects.

It is a schematic diagram which shows the structure of the battery before sealing a frame with an exterior film. It is the II-II line section of Drawing 1, and is a fragmentary sectional view showing the section shape of the welding surface of a frame. It is the schematic diagram which showed the welding process of the frame which concerns on a 1st Example, and an exterior film. It is the schematic diagram which showed the welding state of the frame which concerns on a 1st Example, and an exterior film. It is the schematic diagram which showed the cross-sectional shape of the welding surface of the frame which concerns on a 2nd Example, and showed the welding process of a frame and an exterior film. It is the schematic diagram which showed the cross-sectional shape of the welding surface of the frame which concerns on a 3rd Example, and the welding process of a frame and an exterior film. It is a schematic diagram which shows the shape which looked at the welding surface of the frame which concerns on 4th Example from the top. It is the schematic diagram which showed the welding process of a frame and an exterior film while showing the VIII-VIII line cross section of FIG.

Explanation of symbols

10 Lithium secondary battery 12 Exterior film 14, 114, 214, 314 Frame 16, 116, 216, 316 Welding surface 18, 118, 218, 318 Recess 20, 120, 220, 320 Convex 22, 122, 222, 322 Opening

Claims (4)

A battery sealing method for sealing an opening of a frame body containing a power generation element with an exterior film,
A step of positioning the exterior film with respect to the frame so that the opening of the frame is covered with the exterior film;
Comprising a step of welding the welding surface formed on the periphery of the opening of the frame and the exterior film;
Before welding, a convex portion and a concave portion are formed in close proximity to at least a part of the welding surface of the frame body, and the concave portion has a hollow volume that is greater than or equal to the protruding volume of the convex portion,
In the melting step, at least the convex portion of the welding surface of the frame body is heated and melted.   2. The seal according to claim 1, wherein before the welding, the convex portion is formed in an annular shape along the circumferential direction of the peripheral edge of the opening, and the concave portion is also formed in an annular shape along the peripheral direction of the peripheral edge of the opening. Stop method. A battery frame housing a power generation element,
An opening sealed by an exterior film;
A welding surface formed at the periphery of the opening;
A convex portion and a concave portion formed on at least a part of the welding surface;
The convex part and the recessed part are formed close to each other, and the recessed part has a hollow volume that is greater than or equal to the protruding volume of the convex part.   4. The frame according to claim 3, wherein the convex portion is formed in an annular shape along the circumferential direction of the peripheral edge of the opening, and the concave portion is also formed in an annular shape along the circumferential direction of the peripheral edge of the opening.

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