JP2008159411A - Flat battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flat battery excellent in high-temperature storage characteristics, as rising parts of a gasket are provided in a noncontinuous way on the circumference of a circle. <P>SOLUTION: An internal volume of the battery is aimed to be increased by providing rising parts of a gasket in a noncontinuous way on the circumference of the circle, gaps thus increased are filled with electrolyte solution, and at the same time, a peripheral edge part of a separator is made contained in a separator housing part formed of the rising parts of the gasket and a sealing plate to make up a structure in which the cathode and the sealing plate are isolated by the separator. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a flat battery in which a power generation element is sealed with a positive electrode case, a sealing plate and a gasket, and more particularly to the shape of the gasket.

  In recent years, a flat nonaqueous electrolyte battery (hereinafter simply referred to as a “flat battery”) in which a power generation element in which a nonaqueous electrolyte is combined with an alkali metal or an alloy thereof is housed in a flat battery case is excellent. Since it has reliability and high energy density, it is suitably used as a driving power source for various small electronic devices and a memory backup power source. Up to now, this type of battery has been mainly a primary battery that cannot be recharged. However, in recent years, various rechargeable secondary batteries have been developed, and the demand is increasing as a backup power source for memory and clock functions. Recently, the demand for electronic devices such as mobile phones and digital still cameras has been increasing rapidly. However, along with the downsizing and thinning of these electronic devices, the flat batteries placed inside the devices are also small and thin. Is required.

As a conventional structure, as shown in Patent Document 1, the outer peripheral edge of the flat plate separator is bent inward, and the outer peripheral bent portion is inserted into the gap between the outer periphery of the positive electrode and the inner periphery of the gasket and arranged. Batteries have been proposed. However, in the battery having this structure, it is necessary to insert the outer peripheral bent portion of the separator between the positive electrode and the gasket. Therefore, the positive electrode diameter must be reduced by the thickness of the separator, thereby increasing the positive electrode capacity. I can't. In order to solve this problem, as shown in FIG. 3, the outer peripheral edge of the separator is inserted and fixed in the separator housing part formed by the rising part of the gasket and the sealing plate, thereby reducing the positive electrode diameter. There has been proposed a flat battery that can suppress a decrease in positive electrode capacity without any change (Patent Document 2).
JP 60-148066 A Japanese Patent Application Laid-Open No. 07-282819

  However, in the battery structure of FIG. 3, particularly in a small-diameter battery, the volume of the rising portion of the gasket that occupies the internal volume of the battery increases. When the positive electrode capacity is increased for higher capacity, the amount of the electrolytic solution relative to the positive electrode capacity cannot be secured sufficiently, so that the electrolyte solution is depleted due to long-term storage or high-temperature storage, and the battery characteristic deterioration is accelerated. there were.

  An object of the present invention is to solve such problems, and to provide a flat battery that is excellent in storage stability and does not cause an internal short circuit.

  In order to solve the above problems, the flat battery of the present invention is a flat battery in which a positive electrode, a negative electrode, an electrolyte, and a separator are sealed with a sealing plate that also serves as a negative electrode terminal and a positive electrode case that also serves as a positive electrode terminal through a gasket. The separator is cup-shaped by allowing the rising portion of the gasket to be discontinuously provided on the circumference and storing the peripheral portion of the separator in a separator storage portion formed by the rising portion and the sealing plate. It is formed.

By using the gasket of the present invention, even if the positive electrode expands during discharge, the cup-shaped separator separates the sealing plate from the sealing plate. Therefore, the positive electrode and the sealing plate do not come into contact with each other, and the internal volume can be increased. In addition, by filling the increased voids with the electrolytic solution, it is possible to alleviate the deterioration of battery characteristics due to the depletion of the electrolytic solution due to long-term storage.

  According to the present invention, it is possible to provide a flat battery that is excellent in storability and does not cause an internal short circuit even if it is small.

  A flat battery in which a positive electrode, a negative electrode, an electrolyte, and a separator are sealed by a sealing plate that also serves as a negative electrode terminal and a positive electrode case that also serves as a positive electrode terminal via a gasket, and the rising portion of the gasket is discontinuous on the circumference. The positive electrode expands at the time of discharge by providing a structure in which the separator is formed in a cup shape by storing the peripheral portion of the separator in a separator storage portion formed by the rising portion and the sealing plate. Even if it is isolated from the sealing plate by the cup-shaped separator, the internal volume can be increased without causing contact between the positive electrode and the sealing plate. Furthermore, by filling the increased voids with the electrolytic solution, it is possible to mitigate the deterioration of battery characteristics accompanying the depletion of the electrolytic solution due to long-term storage.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings, taking a non-aqueous electrolyte secondary battery as an example. The present invention is not limited to the secondary battery.

  The flat battery of the present invention shown in FIG. 1 is integrally formed using a positive electrode case 12 that also serves as one electrode terminal, and a clad material of aluminum alloy and stainless steel that also serves as the other electrode terminal and can absorb and release lithium. The power generating element is sealed by a molded sealing plate 11, a gasket 13 that insulates the positive electrode case 12 and the sealing plate 11.

  The gasket 13 has a rising portion discontinuously provided on the circumference, and the peripheral portion of the separator 14 is stored in a separator storage portion formed by the rising portion and the sealing plate 11, so that the shape thereof is obtained. It is characterized by making it into a cup shape. In other words, in the present embodiment, the shape of the gasket 13 has the greatest feature. By making the gasket 13 in the present invention have the above-described structure, the aluminum surface of the sealing plate 11 is covered with the separator 14 when viewed from the positive electrode 16 side, so that a state in which the aluminum surface is not exposed can be created. For this reason, even when the positive electrode 16 expands due to battery discharge, the positive electrode 16 and the aluminum surface do not come into contact with each other.

  Furthermore, since the rising part of the gasket 13 is provided discontinuously on the circumference, the battery internal volume can be increased. By filling the increased gap with the electrolytic solution, the amount of the electrolytic solution with respect to the positive electrode capacity can be increased as compared with the conventional flat battery shown in FIG. As a method of increasing the amount of the electrolyte solution with respect to the positive electrode capacity, there is a reduction in the positive electrode capacity, but in this case, it is disadvantageous in that the battery capacity is reduced. In the flat battery of the present invention, battery characteristic deterioration due to depletion of the electrolyte during long-term storage or high-temperature storage can be suppressed without causing a decrease in battery capacity. Therefore, a flat battery having a high capacity and excellent long-term storage can be obtained. In particular, in the case of a small-diameter size, it is difficult to reduce the thickness on the gasket side due to the problem of workability, so that the rising portion of the gasket is relatively large with respect to the radial direction. For this reason, the smaller the size, the more the flat battery of the present invention shown in FIG. 1 is more advantageous in terms of storage characteristics than the conventional flat battery shown in FIG.

Further, at least two rising portions of the gasket 13 are provided, and the length of the chord of the arc at the innermost diameter of the leading end of the rising portion of the gasket 13 is close to the end of the arc at the innermost diameter of the leading end of the rising portion. It is preferable that it is 0.1 times or more of the distance of the end of the arc of the innermost diameter of the tip. When this distance is less than 0.1 times, the rising portion of the gasket 13 for fixing the separator 14 becomes too small, and the separator 14 tries to partially return to a flat plate shape. For this reason, it becomes difficult to fix the separator 14 in a cup shape stably. Thereby, when viewed from the positive electrode 16 side, the aluminum surface of the sealing plate 11 is not partially covered with the separator 14, and the aluminum surface is partially exposed. For this reason, when the positive electrode 16 expands due to the battery discharge, the positive electrode 16 and the aluminum surface come into contact with each other, and there is a risk of causing an internal short circuit.

  On the other hand, the length of the chord of the arc of the innermost diameter of the tip of the rising portion of the gasket 13 is the end of the arc of the innermost arc of the tip of the rising portion adjacent to the end of the arc of the innermost diameter of the tip of the rising portion. When the distance is 0.5 times or more, the separator 14 can be stably fixed in a cup shape. For this reason, even when the positive electrode 16 expands due to battery discharge, the positive electrode 16 and the aluminum surface do not come into contact with each other.

  On the other hand, the length of the chord length of the arc of the innermost inner diameter of the tip of the rising portion of the gasket 13 is the distance between the end of the innermost arc of the uppermost inner diameter of the tip of the rising portion If it is larger than 2.0 times, the battery internal volume cannot be increased significantly. Therefore, the amount of the electrolyte with respect to the positive electrode pellet cannot be increased, and the characteristic deterioration caused by the depletion of the electrolyte during high-temperature storage can be prevented. It cannot be prevented sufficiently.

  Hereinafter, preferred embodiments of the present invention will be described.

(Example 1)
FIG. 1 is a cross-sectional view of a flat battery of the present invention.

  As Example 1, a flat battery having a diameter of 4.8 mm and a thickness of 1.4 mm shown in FIG. 1 was produced under the following conditions. The sealing plate 11 also serves as a negative electrode terminal, and is a clad material of stainless steel (SUS304, thickness 0.10 mm) having excellent corrosion resistance and an aluminum alloy (thickness 0.10 mm) capable of inserting and extracting lithium. Consists of. The positive electrode case 12 also serves as a positive electrode terminal and is made of stainless steel (SUS444, thickness 0.10 mm) having excellent corrosion resistance. For the separator 14 disposed between the positive electrode 16 and the lithium metal 15, polypropylene having a thickness of 0.10 mm was used. The gasket 13 insulates the sealing plate 11 and the positive electrode case 12 and physically seals the power generation element in the battery container, and uses polypropylene. A plan view and a cross-sectional view of the gasket 13 are shown in FIGS. The gasket 13 has a side thickness and a bottom thickness of 0.25 mm, and the innermost diameter of the gasket bottom portion without the rising portion of the gasket is 3.0 mm. The gasket has three rising portions with a thickness of 0.20 mm and a height of 0.50 mm. The length a of the chord of the innermost arc of the leading end of the gasket is 1.2 mm, and the leading end of the rising portion. The distance b between the end of the innermost arc of the rising portion adjacent to the end of the innermost arc is 1.2 mm and the length a of the string is 1.0 times the distance b. The peripheral portion of the separator 14 is accommodated in the separator accommodating portion formed by the rising portion of the gasket 13 and the sealing plate 11 so that the shape of the separator 14 is cup-shaped. A solution obtained by diluting butyl rubber with toluene was applied between the gasket 13 and the sealing plate 11 and the positive electrode case 12 and the gasket 13, and the toluene was evaporated to obtain a sealant made of a butyl rubber film.

The positive electrode 16 is composed of monoclinic niobium pentoxide (BET specific surface area 1.5 m ² / g) obtained by firing niobium hydroxide at 1000 ° C. as an active material, carbon black and binder as a conductive agent. Fluororesin powder was mixed as an agent, molded into a pellet, and then dried at 250 ° C. for 12 hours to obtain a mass of 10 mg, a diameter of 2.3 mm, and a thickness of 0.90 mm.

On the other hand, the negative electrode has lithium metal 15 (on the surface of the aluminum alloy existing inside the sealing plate 11).
When the battery is assembled, by injecting an electrolyte, the lithium metal 15 and aluminum are short-circuited, and the lithium metal 15 is electrochemically occluded in the aluminum metal. can get. Further, as the electrolytic solution, a solution obtained by dissolving bistrifluoromethanesulfonimide lithium LiN (CF ₃ SO ₂ ) ₂ at a rate of 1 mol / liter in an equal volume mixed solvent of polypropylene carbonate and 1,2-dimethoxyethane is used. The total volume of the separator 14, the lithium metal 15, the positive electrode 16, and the electrolyte solution was set to 95% with respect to the space volume in the battery formed by the sealing plate 11, the positive electrode case 12, and the gasket 13.

(Comparative Example 1)
As Comparative Example 1, a flat battery shown in FIG. Polypropylene is used for the gasket 33, the rising part of the gasket is 0.20 mm in thickness and 0.50 mm in height, and the rising part of the gasket is continuously provided on the circumference as shown in FIG. The separator is formed in a cup shape by storing the peripheral edge of the separator in the separator storage portion formed by the sealing plate. In the other configuration, the total volume of the separator 14, the lithium metal 15, the positive electrode 16, and the electrolytic solution is the same as that of the first embodiment with respect to the internal volume of the battery formed by the sealing plate 11, the positive electrode case 12, and the gasket 13. This is a flat type battery that is 95%.

(Comparative Example 2)
As Comparative Example 2, a flat battery shown in FIG. Polypropylene is used for the gasket 53, and the rising portion of the gasket is not provided as shown in FIG. Although the separator is formed in a cup shape, the peripheral edge of the separator is not housed and fixed. In the other configuration, the total volume of the separator 14, the lithium metal 15, the positive electrode 16, and the electrolytic solution is the same as that of the first embodiment with respect to the internal volume of the battery formed by the sealing plate 11, the positive electrode case 12, and the gasket 13. This is a flat type battery that is 95%.

  100 batteries of Example 1 and Comparative Examples 1 and 2 were prepared, respectively, and at a temperature of 20 ° C., an applied voltage of 2.0 V, a charge protection resistance of 10 kΩ, a constant voltage charge of a charging time of 50 hours, and a temperature of 20 ° C. Then, a constant resistance of 100 kΩ was connected, and 10 charging / discharging cycles were repeatedly repeated until the battery voltage reached 1.0 V, and the proportion of batteries that caused an internal short circuit after 10 cycles was confirmed. The results are shown in Table 1.

実施例１、および比較例１の電池では、ガスケットの立ち上がり部と封口板とで形成されてなるセパレータ収納部に、セパレータ１４の周縁部が収納させることにより、セパレータをカップ状により安定に固定することが出来る。このため、正極側から見て、封口板１１のアルミニウム面がセパレータ１４で覆われているため、アルニウム面が露出しない状態が作り出せ、電池の充放電に伴う正極の膨張が起こる場合においても、正極と、アルミニウム面が接触することがない。一方、比較例２の電池ではセパレータをカップ状に安定に固定することが困難となるため、正極側から見て、封口板のアルミニウム面が部分的
にセパレータで覆われず、アルニウム面が部分的に露出した状態となる。このため、電池の放電に伴う正極１６の膨張が起こる場合、正極１６とアルミニウム面が接触し、内部短絡を引き起こしたものと考えられる。

In the batteries of Example 1 and Comparative Example 1, the separator is stably fixed in a cup shape by allowing the peripheral portion of the separator 14 to be accommodated in the separator accommodating portion formed by the rising portion of the gasket and the sealing plate. I can do it. For this reason, since the aluminum surface of the sealing plate 11 is covered with the separator 14 when viewed from the positive electrode side, the state in which the aluminum surface is not exposed can be created, and the positive electrode is expanded even when the positive electrode expands due to charging / discharging of the battery. And the aluminum surface does not contact. On the other hand, in the battery of Comparative Example 2, it is difficult to stably fix the separator in a cup shape. Therefore, when viewed from the positive electrode side, the aluminum surface of the sealing plate is not partially covered with the separator, and the aluminum surface is partially Will be exposed. For this reason, when expansion of the positive electrode 16 accompanying discharge of the battery occurs, it is considered that the positive electrode 16 and the aluminum surface contacted each other, thereby causing an internal short circuit.

  Next, after the battery was fully charged by a constant voltage charge at a temperature of 20 ° C., an applied voltage of 2.0 V, a charge protection resistance of 10 kΩ, and a charge time of 50 hours, a constant resistance of 100 kΩ was connected at a temperature of 20 ° C. The discharge was performed until reaching 1.0 V, and the initial capacity was confirmed for each of 20 pieces, and the battery fully charged under the above conditions was stored in an environment of 60 ° C. for 200 days, and then at a temperature of 20 ° C. A constant resistance of 100 kΩ was connected, discharging was performed until the battery voltage reached 1.0 V, and the remaining capacity was confirmed for each of 20 pieces. Table 2 shows the average value of the initial capacity of each battery and the average value of the remaining capacity of the batteries stored for 200 days in an environment of 60 ° C.

初期容量に関しては、実施例１、比較例１〜比較例２において顕著な差が見られない。これは初期においては正極ペレットに対する電解液量が十分に確保されているためであると考えられる。一方、６０℃、２００日保存後の残存容量については、比較例１では初期容量に対する残存容量比率がおよそ６０％であるのに対して、実施例１、比較例２の初期容量に対する残存容量比率はおよそ８５％程度であり、比較例１と比べて約２５％の向上が見られる。

Regarding the initial capacity, there is no significant difference between Example 1 and Comparative Examples 1 and 2. This is considered to be because the amount of the electrolytic solution with respect to the positive electrode pellet is sufficiently secured in the initial stage. On the other hand, with respect to the remaining capacity after storage at 60 ° C. for 200 days, the ratio of the remaining capacity to the initial capacity in Comparative Example 1 is approximately 60%, whereas the ratio of the remaining capacity to the initial capacity in Example 1 and Comparative Example 2 is approximately 60%. Is about 85%, which is an improvement of about 25% compared to Comparative Example 1.

  In the battery of Example 1, the rising portion of the gasket is discontinuously provided on the circumference, so that the internal volume of the battery is increased. In the battery of Comparative Example 2, the rising portion is not provided. The product is increasing. Since the increased voids are filled with the electrolytic solution, the amount of the electrolytic solution with respect to the positive electrode pellet can be increased as compared with the battery of Comparative Example 1. For this reason, it is difficult to cause depletion of the electrolyte during high-temperature storage. Thereby, it is considered that the high-temperature storage performance is improved.

  In this embodiment, polypropylene is used as the separator material, but polyphenylene sulfide, polyether ether ketone, perfluoroalcogin, glass fiber, or the like may be used. Further, as a gasket material, polyphenylene sulfide, polyether ether ketone, perfluoroalcogin and the like can be applied in addition to polypropylene.

  Further, in this embodiment, SUS304 is used as the sealing plate and SUS444 is used as the positive electrode case, but the same effect can be obtained by using stainless steel such as SUS316 and SUS430.

  Moreover, this invention is not limited to the kind of positive electrode active material or electrolyte solution.

  Next, the length of the chord of the arc of the innermost arc of the leading end of the gasket and the distance between the end of the arc of the innermost arc of the leading end of the rising portion and the end of the arc of the innermost arc of the leading end of the rising portion were changed. Detailed examination was performed using a gasket.

(Example 2)
The length of the arc of the innermost arc of the leading end of the gasket at the rising end of the gasket is 0.197 mm, and the innermost arc of the leading end of the rising portion adjacent to the end of the innermost arc of the rising end of the rising A battery of Example 2 similar to the battery of Example 1 was prepared, except that the end distance was 1.97 mm and the string length a was 0.1 times the distance b.

(Example 3)
The length of the chord of the arc at the tip innermost diameter of the leading end of the gasket is 0.785 mm on the gasket 13, A battery of Example 3 similar to the battery of Example 1 was prepared, except that the end distance was 1.57 mm and the string length a was 0.5 times the distance b.

Example 4
The length of the arc of the innermost arc of the leading end of the gasket at the rising end of the gasket is 1.57 mm, and the arc of the innermost arc of the leading end of the rising portion adjacent to the end of the innermost arc of the rising end A battery of Example 4 similar to the battery of Example 1 was produced, except that the end distance was 0.785 mm and the string length a was 2.0 times the distance b.

(Example 5)
The length of the arc of the innermost arc of the leading end of the gasket at the rising portion of the gasket is 1.594 mm, and the innermost arc of the leading end of the rising portion adjacent to the end of the innermost arc of the rising end of the rising portion A battery of Example 5 similar to the battery of Example 1 was produced, except that the end distance was 0.759 mm and the string length a was 2.1 times the distance b.

  100 batteries of each of Example 2 to Example 5 were manufactured, applied at a temperature of 20 ° C., an applied voltage of 2.0 V, a charge protection resistance of 10 kΩ, a constant voltage charge of a charging time of 50 hours, and a temperature of 20 ° C. of 100 kΩ. 10 cycles of charging / discharging cycles in which a constant resistance was connected and discharging was performed until the battery voltage reached 1.0 V were performed, and the battery that caused an internal short circuit after 10 cycles was confirmed. Table 3 shows the percentage of batteries that caused an internal short circuit after 10 charge / discharge cycles.

実施例２〜実施例５の電池では、ガスケットの立ち上がり部と封口板とで形成されてなるセパレータ収納部に、セパレータ１４の周縁部が収納させることにより、セパレータをカップ状により安定に固定することが出来る。このため、正極側から見て、封口板１１のアルミニウム面がセパレータ１４で覆われているため、アルニウム面が露出しない状態が作り出せ、電池の充放電に伴う正極の膨張が起こる場合においても、正極と、アルミニウム面が接触することがない。

In the batteries of Examples 2 to 5, the separator is stably fixed in a cup shape by allowing the peripheral part of the separator 14 to be accommodated in the separator accommodating part formed by the rising part of the gasket and the sealing plate. I can do it. For this reason, since the aluminum surface of the sealing plate 11 is covered with the separator 14 when viewed from the positive electrode side, the state in which the aluminum surface is not exposed can be created, and the positive electrode is expanded even when the positive electrode expands due to charging / discharging of the battery. And the aluminum surface does not contact.

Next, after the battery was fully charged by constant voltage charging at an applied voltage of 2.0 V at a temperature of 20 ° C., a charging protection resistance of 10 kΩ and a charging time of 50 hours, a constant resistance of 100 kΩ was connected at a temperature of 20 ° C. The battery is discharged until the voltage reaches 1.0 V and the initial capacity is confirmed for each of the 20 batteries, and the battery fully charged under the above conditions is stored for 200 days in an environment of 60 ° C., and then at a temperature of 20 ° C. Then, a constant resistance of 100 kΩ was connected, discharging was performed until the battery voltage reached 1.0 V, and the remaining capacity was confirmed for each of the 20 pieces. Table 2 shows the average value of the initial capacity of each battery and the average value of the remaining capacity of the batteries stored for 200 days in an environment of 60 ° C.

初期容量に関しては、実施例２〜実施例５において顕著な差が見られない、これは初期においては正極ペレットに対する電解液量が十分に確保されているためであると考えられる、一方、６０℃、２００日後の残存容量については、実施例２では初期容量に対する残存容量比率がおよそ８７％、実施例３ではおよそ８６％、実施例４ではおよそ８３％であるのに対して、実施例５はおよそ７５％程度であり、実施例２〜比較例４と比べて約１０％の低下が見られる。実施例５の電池はガスケットの立ち上がり部が円周上に非連続に設けられていることで電池内容積の増大が図られているものの、実施例２〜実施例４の電池と比べて増大量が小さいため、比較的高温保存における電解液の枯渇を招き易い。これらの結果よりガスケットの立ち上がり部の先端部最内径の円弧の弦の長さが、立ち上がり部の先端部最内径の円弧の端部と近接する立ち上がり部の先端部最内径の端部の距離の０．１倍以上、２．０倍以下であることが好ましい。

Regarding the initial capacity, there is no significant difference in Examples 2 to 5, which is considered to be because the amount of the electrolytic solution with respect to the positive electrode pellet is sufficiently secured in the initial stage, while 60 ° C. As for the remaining capacity after 200 days, in Example 2, the ratio of the remaining capacity to the initial capacity is approximately 87%, in Example 3, it is approximately 86%, and in Example 4, it is approximately 83%. It is about 75%, and a decrease of about 10% is seen as compared with Example 2 to Comparative Example 4. In the battery of Example 5, although the rise of the gasket is discontinuously provided on the circumference to increase the battery internal volume, it is increased in comparison with the batteries of Examples 2 to 4. Therefore, the electrolyte solution tends to be depleted during storage at a relatively high temperature. From these results, the length of the arc chord of the innermost arc of the rising end of the gasket is the distance between the end of the innermost arc of the rising end and the innermost end of the rising end adjacent to the end of the innermost arc of the rising end. It is preferably 0.1 times or more and 2.0 times or less.

  In this embodiment, polypropylene is used as the separator material, but polyphenylene sulfide, polyether ether ketone, perfluoroalcogin, glass fiber, or the like may be used. Further, as a gasket material, polyphenylene sulfide, polyether ether ketone, perfluoroalcogin and the like can be applied in addition to polypropylene.

  Moreover, this invention is not limited to the kind of positive electrode active material or electrolyte solution.

  The present invention aims to increase the internal volume by making the rising part of the gasket on the circumference discontinuous, and to fill the increased gap with the electrolyte, thereby preventing significant capacity deterioration due to depletion of the electrolyte due to long-term storage. Further, it is possible to provide a flat battery excellent in high temperature storage stability and prevention of internal short circuit, in which an internal short circuit is prevented by stably fixing the separator in a cup shape.

Sectional view of the flat battery of the present invention (A) Plan view of the gasket of the present invention, (b) Sectional view Cross-sectional view of a conventional flat battery (A) Plan view of conventional gasket, (b) Cross section Cross-sectional view of a flat battery using a gasket with no rising part (A) Plan view of gasket without rising part, (b) Cross section

Explanation of symbols

11 Sealing plate 12 Positive electrode case 13, 33, 53 Gasket 14 Separator 15 Lithium metal 16 Positive electrode

Claims (2)

  A flat battery in which a positive electrode, a negative electrode, an electrolyte, and a separator are sealed by a sealing plate that also serves as a negative electrode terminal and a positive electrode case that also serves as a positive electrode terminal via a gasket, and the rising portion of the gasket is discontinuous on the circumference. A flat battery, wherein the separator is formed by the rising portion and the sealing plate, and the peripheral portion of the separator is housed in the separator housing portion and the separator is fixed in a cup shape.   At least two rising portions are provided, and the length of the chord of the arc of the innermost inner diameter of the upper end of the rising portion is the innermost diameter of the distal end of the rising portion adjacent to the end of the arc of the innermost inner diameter of the upper end of the rising portion. The flat battery according to claim 1, wherein the distance is 0.1 to 2.0 times the distance from the end of the arc.

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