JP2010073570A - Flat battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flat battery advantageous for achieving high capacity while ensuring sealing capability. <P>SOLUTION: The flat battery 1 is formed by sealing the opening of an outer can 2 with a sealing can 3, the outer can 2 and the sealing can 3 have a cylinder shape formed by standing a surrounding wall in the periphery of a bottom and opening one end, the tip 12a of a surrounding wall 12 of the outer can 2 is bent toward the center axis 9 of the sealing can 3, the outer can 2 is crimped to the sealing can 3, a surrounding wall 16 of the sealing can 3 is a single wall having no turning up in the cross section shape in the center axis 9 direction of the sealing can 3 and continuing to a bottom 15 through a corner part 18, a standing portion 13 interposed between the tip 12a of the surrounding wall 12 of the bent outer can 2 out of the surrounding wall 16 of the sealing can 3 and a bottom 11 of the outer can 2 is thicker than the corner part 18, and the Vickers hardness of the standing portion 13 is larger than that of the corner part 18. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a flat battery called a coin battery or a button battery.

  A flat battery called a coin battery or a button battery is used as a power source mainly for memory backup of information equipment and video equipment. FIG. 14 shows a perspective view of an example of a conventional flat battery. The flat battery 100 is a combination of an outer can 101 that is a positive electrode can and a sealing can 102 that is a negative electrode can.

  15 is a cross-sectional view taken along line CC of FIG. In the flat battery 100, a power generation element 110 is accommodated and filled with a non-aqueous electrolyte. A gasket 103 is interposed between the peripheral wall 104 of the outer can 101 and the folded portion 107 of the peripheral wall 105 of the sealing can 102. By forming the folded portion 107 in the sealing can 102, the strength of the close contact portion with the gasket 103 is ensured.

  The front end 104 a of the peripheral wall 104 of the outer can 101 is curved toward the central axis 106 side of the sealing can 102, and the outer can 101 is caulked and fixed to the sealing can 102. Thus, the gap between the outer can 101 and the sealed can 102 is sealed by the gasket 103, and the outer can 101 and the sealed can 102 having different polarities are insulated.

  For example, the following patent documents 1 and 2 are also described as the flat battery having a configuration corresponding to the folded portion 107. The configuration in which the folded portion 107 is formed is advantageous in terms of strength but disadvantageous in terms of increasing the capacity.

  Specifically, the outer dimension of the flat battery 100 is defined as a predetermined dimension. In the flat battery having the same outer dimensions, the configuration with the folded portion 107 moves the corner portion 108 of the sealing can 102 toward the central shaft 106 as compared with the configuration without the folded portion 107, and the capacity is accordingly increased. Becomes smaller.

On the other hand, the following Patent Documents 3-6 describe a configuration without the folded portion 107, and each of these configurations is advantageous in terms of increasing the capacity.
WO02 / 013290 Publication JP 2003-151511 A JP-A-7-57706 JP 2003-68254 A JP-A-4-341756 Japanese Patent No. 3399801

  However, the configuration without the folded portion 107 as proposed in Patent Documents 3-6 is advantageous in terms of increasing the capacity, but is disadvantageous in terms of strength. Specifically, in FIG. 15, when the tip 104 a of the peripheral wall 104 of the outer can 101 is bent toward the central axis 106 and caulked, the peripheral wall 105 of the sealing can 102 is also deformed toward the central axis 106. . That is, the peripheral wall 105 is deformed in a direction away from the inner peripheral surface of the gasket 103. At this time, in the configuration without the folded-back portion 107, the adhesion between the peripheral wall 105 and the gasket 103 becomes weak, and sealing with the gasket 103 may be insufficient.

  In Patent Document 3, a configuration for preventing such insufficient sealing is proposed, but there is no proposal to make up for insufficient strength, and processing for changing the thickness of the peripheral wall is also necessary. .

  The present invention solves the above-described conventional problems, and an object of the present invention is to provide a flat battery that is advantageous for increasing the capacity while ensuring sealing performance.

  In order to achieve the above object, the flat battery of the present invention is a flat battery in which an opening of an outer can is sealed with a sealing can, and the outer can and the sealing can have a peripheral wall standing on the outer periphery of the bottom. A cylindrical opening at one end, and a distal end portion of a peripheral wall of the outer can is curved toward the central axis of the sealed can, and the outer can is caulked and fixed to the sealed can. In the cross-sectional shape in the central axis direction, the peripheral wall of the sealing can is a single wall that is not folded back, and is connected to the bottom via a corner portion, and the curved exterior of the peripheral wall of the sealing can The standing part sandwiched between the tip of the peripheral wall of the can and the bottom part of the outer can has a thickness larger than the thickness of the corner part, and the Vickers hardness of the standing part is the Vickers hardness of the corner part. It is characterized by being larger.

  According to the present invention, it is advantageous to increase the capacity while ensuring sealing performance.

  According to the flat battery of the present invention, the peripheral wall of the sealing can is formed with the standing portion whose thickness and hardness are larger than the corner portion, so that deformation of the standing portion can be suppressed during caulking. The sealing property by the gasket is maintained.

  In the flat battery of the present invention, it is preferable that a Vickers hardness is larger than a Vickers hardness of the corner portion over the entire peripheral wall of the sealing can. According to this configuration, at the time of caulking, deformation of the entire peripheral wall of the sealing can is suppressed, which is further advantageous for preventing deterioration in sealing performance.

  Moreover, it is preferable that the corner part has a Vickers hardness of 150 or more, and the standing part has a Vickers hardness of 200 or more.

  Moreover, it is preferable that the Vickers hardness of the said standing part is 1.05 times or more of the Vickers hardness of the said corner part.

  Moreover, it is preferable that the said standing part is work-hardened by the process which compresses the surrounding wall of the said sealing can.

  The gasket is preferably pressed against the peripheral wall of the sealing can so as to press the peripheral wall of the sealing can toward the central axis. According to this configuration, the insulation and sealing properties between the outer can and the sealed can with different polarities are improved.

Further, the peripheral wall of the sealing can forms a step through a shoulder portion, the gasket is interposed between the shoulder portion and the peripheral wall of the exterior can, and in the height direction of the sealing can It is preferable that the gasket is pressed. Also by this structure, the insulation and sealing performance between an exterior can and a sealing can having different polarities are improved. Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a perspective view of a flat battery according to an embodiment of the present invention. The flat battery 1 is a combination of an outer can 2 that is a positive electrode can and a sealing can 3 that is a negative electrode can. An example of the flat battery 1 is one having an outer diameter (D dimension in FIG. 2) of 20.0 mm and a thickness of 5 mm.

  2 is a cross-sectional view taken along line AA in FIG. The outer can 2 has a cylindrical shape in which a peripheral wall 12 is erected on the outer periphery of the bottom 11 and one end is opened. The sealing can 3 has a cylindrical shape in which a peripheral wall 16 is erected on the outer periphery of the bottom portion 15 and one end is opened. A gasket 4 is interposed between the inner peripheral surface of the peripheral wall 12 of the outer can 2 and the outer peripheral surface of the peripheral wall 16 of the sealing can 3.

  The distal end portion 12 a of the peripheral wall 12 of the outer can 2 is curved toward the central axis 9 side of the sealing can 3, and the outer can 2 is caulked and fixed to the sealing can 3. Thus, the gap between the outer can 2 and the sealed can 3 is sealed by the gasket 4 and the outer can 2 and the sealed can 3 having different polarities are insulated.

  In the flat battery 1, a power generation element 10 is accommodated and filled with a nonaqueous electrolytic solution. The power generation element 10 includes a positive electrode material (electrode material) 5 in which a positive electrode active material or the like is hardened in a disk shape, a negative electrode material (electrode material) 6 in which a metal lithium or a lithium alloy as a negative electrode active material is formed in a disk shape, and a non-woven fabric The separator 7 is included. A positive electrode material 5 and a negative electrode material 6 are arranged via a separator 7. A positive electrode ring 8 made of stainless steel or the like is mounted on the outer surface of the positive electrode material 5.

  FIG. 3 shows an exploded view of the flat battery 1 shown in FIG. As described above, the outer can 2 and the sealing can 3 have a cylindrical shape with one end opened. These can be formed, for example, by press-molding a stainless material. The peripheral wall portion 16 of the sealing can 3 includes a straight portion 17, and a corner portion 18 is formed at the intersection of the bottom portion 15 and the straight portion 17. Further, the peripheral wall portion 16 forms a step through the shoulder portion 19.

  The gasket 4 is a resin molded product, and is molded by a resin composition containing, for example, polyphenylene sulfide (PPS) as a main component and an olefin elastomer. The gasket 4 is a ring-shaped member, and an inner wall 21 and an outer wall 22 rise from the base portion 20. A gap 23 is formed between the inner wall 21 and the outer wall 22. The peripheral wall 16 of the sealing can 3 can be inserted into the gap 23.

  The positive electrode material 5 is formed by integrally forming a positive electrode active material in a disc shape with the positive electrode ring 8. Examples of the positive electrode active material include a material obtained by molding a positive electrode mixture prepared by mixing manganese dioxide with graphite, a tetrafluoroethylene-hexafluoropropylene copolymer, and hydroxypropylcellulose.

  The separator 7 is formed of a nonwoven fabric, for example, a nonwoven fabric made of polybutylene terephthalate fibers.

The separator 7 is impregnated with a non-aqueous electrolyte. As the non-aqueous electrolyte, for example, a solution in which LiClO ₄ is dissolved in a solvent in which propylene carbonite and 1,2-dimethoxyethane are mixed can be used. The thickness of the separator 7 is, for example, about 0.3 to 0.4 mm.

  Although the schematic configuration of the flat battery 1 has been described above, the flat battery 1 according to the present embodiment is characterized by the hardness and thickness distribution of the sealing can 3. Specifically, in the peripheral wall 16 of the sealing can 3 in FIG. 2, the thickness of the standing portion 13 is larger than the thickness of the corner portion 18. Furthermore, the Vickers hardness of the standing portion 13 is larger than the Vickers hardness of the corner portion 18.

  The standing portion 13 is a portion sandwiched between the tip portion 12 a of the peripheral wall 12 of the curved outer can 2 and the bottom portion 11 of the outer can 2. In the shoulder mold 19, an outside portion is included in the standing portion 13 with respect to the extension line 14 of the inner peripheral surface of the standing portion 13.

  As will be described in detail later, the standing portion 13 having increased hardness and thickness is formed at the time of the caulking process for curving the front end portion 12 a of the peripheral wall 12 of the outer can 2. This is to prevent the deformation of the peripheral wall 16 and ensure the sealing performance by the gasket 4.

  Here, the Vickers hardness is a hardness measured according to JISZ2244. At the time of measurement, a diamond square conical indenter having a diagonal surface of 136 degrees is used to form a dent on the test surface, and the surface area of the permanent dent is obtained from the diagonal length of the permanent dent. The Vickers hardness is obtained from the value obtained by dividing the indented test load by the surface area of the permanent indentation.

  Hereinafter, a molding method for obtaining the standing portion 13 of the sealing can 3 as described above will be described with reference to FIGS. FIG. 4 shows a state in which the disk-like member 41 is punched from the plate 40 that is the raw material of the sealing can 3. The disk-shaped member 41 is processed by a transfer press. The transfer press is a press machine that includes a die corresponding to each of the multi-steps and a transfer mechanism that transports a workpiece to the next step. The disk-like member 41 is processed by a mold corresponding to each process and formed into the shape shown in FIG.

  FIG. 5 shows the change in the shape of the workpiece after each step. Each figure of (a)-(e) has shown the top view and sectional drawing. FIG. 5A shows a disk-like member 41. As described above, the disc-like member 41 is punched from the plate member 40 as shown in FIG. In FIG. 5B, the disk-like member 41 is processed into a cylindrical shape in which a peripheral wall 43 is erected on the outer periphery of the bottom portion 42 by drawing.

  FIG. 5C shows a state after the hitting process. Although the state of FIG. 5C does not change to being cylindrical, the height of the peripheral wall 43 is adjusted by hitting the peripheral wall 43.

  By this height adjustment, the peripheral wall 43 is compressively deformed and work hardened. As described above, in the standing portion 13 of the peripheral wall 16 of the sealing can 3, the thickness and the Vickers hardness are increased due to the compressive deformation in this tapping process and the work hardening associated therewith.

  FIG. 5D shows a state in which the shoulder portion 45 is formed by processing the corner portion 44 of the processed product of FIG. FIG. 5E shows a completed state after finishing. The completed sealing can has the same shape as the sealing can 3 shown in FIG.

  On the other hand, the sealing can 3 shown in FIG. 3 can also be formed by press working with a progressive die. However, in this processing method, a hitting process cannot be included, and the thickness and hardness of the standing portion 13 (FIG. 2) of the peripheral wall 16 cannot be made larger than the corner portion 18.

  Hereinafter, the molding method of the sealing can 3 by the progressive die will be described as a comparative example. FIG. 6 shows a plan view of the coil material 50 being processed by the progressive die. FIG. 6 also shows a cross-sectional view of the workpiece. Each cross-sectional view is a cross-sectional view in the width direction of the coil material 50 (a cross-sectional view taken along the line BB).

  In the state shown in FIG. 6, by feeding the coil material 50 for one step (in the direction of arrow a), the workpieces (a), (b), and (c) are respectively (b) and (c) one step ahead. ) And (d). In this state, it is processed into a cross-sectional shape at each position through a press for one stroke. That is, every time the coil material is fed for one stroke, multi-step pressing proceeds simultaneously.

  The disk-shaped member 51 of (a) is processed into the drawn shape of (b). The narrowed corner portion 52 of (b) is processed as shown in (c), and a shoulder portion 53 is formed. The workpiece processed in the state of (c) is punched out of the broken line portion in (d) and is separated from the coil material 50. The workpiece cut from the coil material 50 is folded back at the upper end 54 as shown in (e) to form a shape corresponding to the folded-back portion 107 in FIG. The step (e) can be omitted, and the peripheral wall can be a single wall without a folded portion.

  In the forming method shown in FIG. 6, the processing proceeds while the workpiece is integrated with the coil material 50. This molding is the same as the molding method shown in FIG. 5 in that work hardening is obtained at the corner 52 by bending.

  However, in the molding method shown in FIG. 6, there is no step of compressing the peripheral wall of the cylindrical member, and the standing portion 13 (FIG. 2) cannot be processed to make the thickness and hardness larger than the corner portion 18.

  This will be described below with reference to experimental results. FIG. 7 shows the measurement points of the thickness and Vickers hardness of Example 1 and Comparative Example 1. FIG. 7A shows a main part of the sealing can 3 according to the first embodiment. The AH point is the measurement point. FIG. 7A shows the range of the standing portion 13 shown in FIG. As described above, the outer portion is included in the standing portion 13 with respect to the extension line 14 on the inner peripheral surface of the standing portion 13. For this reason, points F, G, and H are measurement points in the standing portion 13.

  Example 1 is a sealing can for coin-shaped batteries having a diameter of 20 mm and a height of 5 mm. The sealing can 3 of Example 1 is the same structure as the sealing can 3 shown in FIG. 3, and the side wall part 16 is a single wall without a folding | turning part. Further, Example 1 was formed by the forming method shown in FIG. 5, and was formed by proceeding to a workpiece punched into a disk shape.

  FIG. 7B shows the main part of the sealing can 102 according to the comparative example 1. A, A ', and BJ points are measurement points. Comparative Example 1 is a sealing can for coin-shaped batteries having a diameter of 24.5 mm and a height of 5 mm. The sealing can 102 of Comparative Example 1 has the same configuration as the sealing can 102 shown in FIG. 15, and a folded portion 107 is formed on the side wall portion 105. Further, Comparative Example 1 is formed by the forming method shown in FIG. 6, and is formed by proceeding processing to a workpiece integrated with the coil material 50.

  FIG. 8 shows the relationship between the measurement point and the Vickers hardness and the relationship between the measurement point and the thickness shrinkage rate in Example 1 and Comparative Example 1. A solid line 60 indicates the Vickers hardness of Example 1, and a broken line 61 indicates the Vickers hardness of Comparative Example 1.

  A solid line 70 indicates the thickness shrinkage rate of Example 1, and a broken line 71 indicates the thickness shrinkage rate of Comparative Example 1. The thickness shrinkage rate indicates the degree of shrinkage relative to the original thickness, and was calculated by the following equation (1). According to the equation (1), the thickness shrinks as the thickness shrinkage rate increases.

Formula (1) Thickness shrinkage rate (%) = [(original thickness−measured value) / original thickness] × 100
First, the solid line 60 indicating the Vickers hardness and the broken line 61 will be compared. In both Example 1 and Comparative Example 1, the hardness at point B (corner part) is higher than that at points A and A ′ (bottom part). This is considered to be due to work hardening by bending of the corner portion. The same applies to points D and F that are corner portions of Example 1 and Comparative Example 1, and H point of Comparative Example 1 that is a bent portion.

  Here, the work hardening extends not only to the bent portion but also to the vicinity thereof. For this reason, in Example 1, it is thought that work hardening reaches also in the C point, E point, and G point which are the corner vicinity. Further, in Example 1, the entire peripheral wall 16 is work-hardened by the hitting process, and is work-hardened also at the point H away from the corner portion (point F).

  In Comparative Example 1, work hardening occurs at points C and E near the corner, and work hardening also occurs at point G near both the corner (F point) and the bent portion (H point). It will be.

  Therefore, both Example 1 and Comparative Example 1 maintain a high value between point B and point H.

  On the other hand, when the Example 1 and the Comparative Example 1 are compared between the points B and H, the hardness of the Example 1 (solid line 60) is almost entirely over the hardness of the Comparative Example 1 (broken line 61). However, it is getting bigger. In particular, in Comparative Example 1 (broken line 61), point C (straight line portion 111) has a lower hardness than point B (corner portion 108), whereas in Example 1 (solid line 60), point C ( The hardness of the straight portion 17) is higher than that of the point B (corner portion 18).

  This is considered to be due to the difference between the molding methods. That is, the difference in magnitude between the hardnesses of point B and point C in Example 1 and Comparative Example 1 is that, as described above, in Example 1, work hardening by the tapping process of FIG. 5C is obtained. On the other hand, in Comparative Example 1, it is considered that there is no process corresponding to the hitting process.

  Next, in FIG. 8, the solid line 70 and the broken line 71 indicating the thickness shrinkage rate (%) will be compared. The scale of thickness shrinkage rate (%) is shown on the right side of FIG. At the point FH corresponding to the standing portion 13 in FIG. 7A, the thickness shrinkage rate of Example 1 (solid line 70) is the thickness shrinkage rate of Comparative Example 1 (broken line 71) throughout. It is getting smaller.

  On the other hand, the thickness shrinkage rate of Example 1 (solid line 70) at the FH point is smaller than the thickness shrinkage rate at the B point (corner portion 18). That is, in Example 1, the thickness of the FH point corresponding to the standing portion 13 is larger than the thickness of the B point (corner portion 18). In contrast, the value of point F in Comparative Example 1 (broken line 71) is above the value of point B (corner portion 108), and the thickness of point F is smaller than that of point B (corner portion 108). .

  As described above, Example 1 is larger in the standing portion 13 than in the corner portion 18 in the standing portion 13 in FIG. 7A. Such a standing portion 13 can be formed because, as described above, the molding method of Example 1 has a tapping process that is not found in the molding method of Comparative Example 1.

  Here, in FIG. 2, the distal end portion 12 a of the peripheral wall 12 of the outer can 2 is curved in the direction of the central axis 9. Thus, the outer can 2 is caulked and fixed to the sealed can 3. As in the first embodiment, the standing portion 13 whose hardness and thickness are larger than those of the corner portion 18 is prevented from being deformed, which is advantageous for securing the sealing performance by the gasket 4. Details of this will be described below with reference to FIGS. 2 and 13 after the manufacturing process has been described with reference to FIGS.

  When assembling the components shown in FIG. 3, the assembly is performed with the top and bottom of FIG. 3 turned upside down. FIG. 9 shows a cross-sectional view of the state during assembly. FIG. 9A is a cross-sectional view showing a state where the gasket 4 is attached to the sealing can 3. The gasket 4 is attached to the sealing can 3 by inserting the peripheral wall 16 of the sealing can 3 into the gap 23 of the gasket 4.

  FIG. 9B shows a state where the power generation element 10 is stored in the sealing can 3. The negative electrode material 6 is fixed to the sealing can 3 with a conductive adhesive or the like. The separator 7 and the positive electrode material 5 are stacked on the negative electrode material 6. Thereafter, a nonaqueous electrolytic solution is injected into the sealing can 3.

  FIG. 10 is a cross-sectional view showing a state in which the outer can 2 is fitted to the assembly of FIG. In this state, the outer peripheral surface of the gasket 4 and the inner peripheral surface of the peripheral wall 12 of the outer can 2 are fitted. The process proceeds from the state shown in FIG. 10 to the caulking process. In the caulking process, the distal end portion 12 b of the peripheral wall 12 of the outer can 2 is bent toward the central axis 9 side of the sealing can 3.

  FIG. 11 is a cross-sectional view showing a state before caulking. The flat battery 1 shown in FIG. 10 is sandwiched between the knockout pin 30 and the punch 31. The mold surface of the sealing mold 32 is fitted to the outer peripheral surface of the peripheral wall 12 so as to surround the peripheral wall 12 of the outer can 2. In this state, the knockout pin 30 and the punch 31 are lowered. As a result, the tip 12 a of the peripheral wall 12 of the outer can 2 is bent along the curved surface of the sealing mold 32 toward the central axis 9 of the sealing can 3.

  FIG. 12 is a cross-sectional view showing a state in which the knockout pin 30 and the punch 31 have been lowered. In this state, the gasket 4 is sandwiched between the inner peripheral surface of the peripheral wall 12 of the outer can 2 and the outer peripheral surface of the peripheral wall 16 of the sealing can 3.

  Furthermore, the tip of the gasket 4 is pressed against the peripheral wall 16 of the sealing can 3 so as to press the peripheral wall 16 toward the central axis 9. This improves the insulation and sealing properties between the outer can 2 and the sealed can 3 having different polarities.

  Further, the gasket 4 is pressed in the height direction of the sealing can 3 between the shoulder 19 of the sealing can 3 and the tip 12 a of the peripheral wall 12 of the outer can 2. This also improves the insulation and sealing between the outer can 2 and the sealed can 3.

  In the state of the finished product after the caulking process in FIG. 2, the front end portion 12 a of the peripheral wall 12 of the outer can 2 is bent toward the central axis 9 side of the sealing can 3. During the bending process, if the peripheral wall 16 of the sealing can 3 is deformed, the sealing performance by the gasket 4 may be lowered.

  In Comparative Example 1, as shown in FIG. 15, the folded portion 107 is formed to increase the strength, thereby preventing the sealing performance from being lowered. On the other hand, in this Embodiment, it replaces with the folding | returning part 107, the standing part 13 of the single wall which enlarged thickness and hardness was formed, and the sealing performance fall is prevented.

  As described above, in Example 1, the thickness of the standing portion 13 is larger than that of the corner portion 18 in FIG. That is, when the thickness of the corner portion 18 of the sealing can 3 is t1, and the thickness of the standing portion 13 is t2, the sealing can 3 according to the present embodiment satisfies the relationship of the following formula (2). Yes.

Formula (2) t1 <t2
Further, as described above, in Example 1, the hardness of the standing portion 13 is higher than that of the corner portion 18 in FIG. That is, when the Vickers hardness of the corner portion 18 of the sealing can 3 is Hv1, and the Vickers hardness of the standing portion 13 is Hv2, the sealing can 3 according to the present embodiment satisfies the relationship of the following formula (3). is doing.

Formula (3) Hv1 <Hv2
According to this configuration, the corner portion 18 is increased in hardness by work hardening after bending, and the standing portion 13 is further harder and thicker than the corner portion 18. become. Therefore, at the time of caulking, deformation of the standing portion 13 can be suppressed, and deterioration of sealing performance can be prevented.

  In order to ensure the effect of the formula (2), it is preferable to satisfy the relationship of the following formula (4), and it is more preferable to satisfy the relationship of the following formula (5).

Formula (4) 1.01 ≦ t2 / t1
Formula (5) 1.05 <= t2 / t1
On the other hand, in consideration of the limit of compression by tapping, t2 / t1 is preferably within the range of the following formula (6).

Formula (6) t2 / t1 <= 1.30
Moreover, in order to ensure the effect by Formula (3), it is preferable to satisfy the relationship of following formula (7), and it is still more preferable to satisfy the relationship of following formula (8).

Formula (7) 1.05 <= Hv2 / Hv1
Formula (8) 1.10 ≦ Hv2 / Hv1
On the other hand, in consideration of the limit of work hardening by tapping, Hv2 / Hv1 is preferably within the range of the following formula (9).

Formula (9) Hv2 / Hv1 ≦ 1.6
Preferred numerical ranges of Hv1 and Hv2 are as follows. The material of the sealing can 3 is usually a stainless material such as SUS430, and the following numerical range is derived from the degree of work hardening by bending of the corner portion in SUS430 and the degree of work hardening by tapping.

  The Vickers hardness Hv1 of the corner portion 18 is preferably in the range of the following formula (10), more preferably in the range of the following formula (11), and further preferably in the range of the following formula (12).

Formula (10) 150 <= Hv1
Formula (11) 170 <= Hv1
Formula (12) 190 <= Hv1
The Vickers hardness Hv2 of the standing portion 13 is preferably in the range of the following formula (13), more preferably in the range of the following formula (14), and further preferably in the range of the following formula (15).

Formula (13) 200 <= Hv2
Formula (14) 210 <= Hv2
Formula (15) 220 <= Hv2
On the other hand, it is difficult to increase the hardness of the corner portion 18, and if the hardness of the corner portion 18 is too high, it is difficult to make the hardness of the standing portion 13 larger than that of the corner portion 18. For this reason, the hardness of the corner portion 18 is preferably within the range of the following formula (16), and more preferably within the range of the following formula (17).

Formula (16) Hv1 <= 210
Formula (17) Hv1 <= 200
Here, as shown by the solid line 60 in FIG. 8, in the first embodiment, not only the standing portion 13 (FH point) but also the entire peripheral wall 16 (CH point), the Vickers hardness is the corner portion 18 ( (B point) is larger. According to this configuration, the hardness of the corner portion 18 is increased by work hardening after bending, and the entire peripheral wall 16 is further increased in hardness than the corner portion 18. In this case, at the time of the caulking process, the deformation of the entire corner portion 18 and the peripheral wall 16 is suppressed, which is more advantageous for preventing deterioration of the sealing performance.

  In addition, although it is not directly related to prevention of deterioration in sealing performance, the bottom portion 15 (FIG. 2) which is a flat portion of the sealing can 3 also needs a certain degree of hardness in order to prevent battery swelling and the like. Become. For this reason, 130 or more are preferable and, as for the Vickers hardness of the bottom part 15, 140 or more are more preferable.

  Next, the present embodiment will be compared with a comparative example with reference to FIG. FIG. 13A is a cross-sectional view of a main part of a flat battery 100 according to a comparative example. This figure has the same configuration as the conventional example shown in FIG. FIG.13 (b) is principal part sectional drawing of the flat battery 1 which concerns on this Embodiment. This figure has the same configuration as the flat battery 1 shown in FIG.

  Both the flat battery 100 and the flat battery 1 have the same outer dimension D. Whereas the flat battery 100 forms the folded portion 107 in the sealing can 102, the peripheral wall 16 of the flat battery 1 is a single wall that is not folded.

  Even if the folded-back portion 107 is omitted from the sealing can 102, the hanging margin between the shoulder portion 109 of the peripheral wall 105 and the gasket 103 does not change. In this case, the entire peripheral wall 105 of the sealing can 102 can be moved to the peripheral wall 104 side of the outer can 101 by the amount that the folded portion 107 is omitted.

  The state after this movement corresponds to FIG. In the flat battery 1 in FIG. 13B, the inner peripheral surface of the sealing can 3 is moved outward by a dimension A as compared to the flat battery 100 in FIG. As a result, the flat battery 1 can have a larger capacity while having the same external dimension D as the flat battery 100.

  Also, the formation of the straight portion 17 is advantageous for securing the capacity. In FIG. 13B, when the radius of the corner portion 18 is increased, the straight portion 17 becomes a part of the corner portion 18. In this configuration, the corner portion 18 is displaced toward the central axis 9, which is disadvantageous for securing the capacity. That is, the capacity can be increased as the radius of the corner portion 18 is reduced and the length of the straight portion 17 is increased.

  On the other hand, as described above, the flat battery 1 forms the standing portion 13 that satisfies the above formulas (2) and (3), and the deformation of the standing portion 13 is suppressed during the caulking process. It is possible to prevent the deterioration of the stopping property.

  That is, the present embodiment can be said to be a configuration that is advantageous for securing the sealing performance by the gasket 4 while the peripheral wall 16 of the sealing can 3 is a single wall that is not folded back and has a structure that is advantageous for high capacity. .

  In addition, although the sealing can 3 which concerns on this Embodiment demonstrated in the example which formed the linear part 17 in the cross-sectional shape of the surrounding wall 16, the structure which does not form the linear part 17 may be sufficient. On the other hand, when the straight portion 17 is formed, the straight portion 17 is formed in the cross-sectional shape of the peripheral wall 16 after caulking. However, an external force is applied to the peripheral wall 16 by caulking, and the linear portion 17 may not be able to maintain a complete linear shape after caulking. Even with such a configuration, the configuration remains advantageous for securing the capacity.

  Therefore, the shape of the straight line portion 17 includes not only a complete straight line but also a curve that has a large radius of curvature and can be regarded as a straight line. More specifically, the shape of the straight portion 17 includes a curve having a radius of curvature of 5 mm or more, or a curve having a radius of curvature of 20 times or more the radius of the corner portion 18.

  Moreover, although the dimension of the flat battery 1 and the material of the component were demonstrated using FIGS. 1-3, these are an example, The thing of another dimension may be used, Even if it uses what was other materials Good.

  As described above, according to the present invention, the flat battery of the present invention is mainly used for memory backup such as information equipment and video equipment, because it is advantageous for high capacity while ensuring sealing performance. It is useful as a power source.

The perspective view of the flat battery which concerns on one embodiment of this invention. Sectional drawing in the AA line of FIG. FIG. 3 is an exploded view of the flat battery 1 shown in FIG. 2. The figure which shows the state which punched the disk-shaped member from the board | plate material which concerns on one embodiment of this invention. The figure which shows the change of the shape of the workpiece which passed through each process which concerns on one embodiment of this invention. The figure which shows the molding method of the sealing can which concerns on a comparative example. The figure which shows the measurement point of the Vickers hardness of Example 1 and Comparative Example 1. The figure which shows the relationship between a measurement point and Vickers hardness about Example 1 and the comparative example 1, and the relationship between a measurement point and thickness shrinkage rate. It is sectional drawing in the middle of the assembly of the flat battery which concerns on one embodiment of this invention, (a) A figure is sectional drawing which shows the state which attached the gasket 4 to the sealing can 3, (b) A figure is a sealing can FIG. 3 is a cross-sectional view showing a state where a power generation element 10 is housed in 3. Sectional drawing which shows the state which made the exterior can 2 fit to the assembly of FIG.9 (b). Sectional drawing which shows the state before crimping which concerns on one embodiment of this invention. Sectional drawing which shows the state after caulking which concerns on one embodiment of this invention. It is sectional drawing for comparing this Embodiment and a comparative example, (a) A figure is sectional drawing of a comparative example, (b) A figure is sectional drawing of this Embodiment. The perspective view of an example of the conventional flat battery. Sectional drawing in CC line of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Flat battery 2 Exterior can 3 Sealing can 4 Gasket 11 Bottom part of exterior can 12 Peripheral wall of exterior can 13 Standing part 15 Bottom part of sealed can 16 Perimeter wall of sealed can 17 Straight part of sealed can 18 Corner part of sealed can 19 Can shoulder

Claims (7)

A flat battery in which the opening of the outer can is sealed with a sealing can,
The outer can and the sealing can have a cylindrical shape in which a peripheral wall is erected on the outer periphery of the bottom, and one end is opened,
The outer wall of the outer peripheral can be curved to the center axis side of the sealed can, and the outer can is caulked and fixed to the sealed can;
In the cross-sectional shape in the central axis direction of the sealing can,
The peripheral wall of the sealing can is a single wall that is not folded back, and is connected to the bottom part through a corner part,
Of the peripheral wall of the sealing can, the standing portion sandwiched between the curved front end of the outer can and the bottom of the outer can has a thickness larger than the corner portion,
A flat battery having a Vickers hardness of the standing portion larger than a Vickers hardness of the corner portion.   2. The flat battery according to claim 1, wherein the peripheral wall of the sealing can extends over the entire area and the Vickers hardness is larger than the Vickers hardness of the corner portion.   The flat battery according to claim 1 or 2, wherein the corner portion has a Vickers hardness of 150 or more, and the standing portion has a Vickers hardness of 200 or more.   4. The flat battery according to claim 1, wherein a Vickers hardness of the standing portion is 1.05 times or more of a Vickers hardness of the corner portion. 5.   The flat battery according to any one of claims 1 to 4, wherein the standing portion is work-cured by a process of compressing a peripheral wall of the sealing can.   The flat battery according to any one of claims 1 to 5, wherein the gasket is pressed against the peripheral wall of the sealing can so as to press the peripheral wall of the sealing can toward the central axis.   The peripheral wall of the sealing can forms a step through a shoulder portion, the gasket is interposed between the shoulder portion and the peripheral wall of the exterior can, and the gasket in the height direction of the sealing can The flat battery according to any one of claims 1 to 6, wherein is pressed.

Images