JP3736247B2

JP3736247B2 - Sealed storage battery and method for manufacturing the same

Info

Publication number: JP3736247B2
Application number: JP37386399A
Authority: JP
Inventors: 勲井門; 孝中嶋
Original assignee: Panasonic Corp; Matsushita Electric Industrial Co Ltd
Current assignee: Panasonic Corp; Panasonic Holdings Corp
Priority date: 1999-12-28
Filing date: 1999-12-28
Publication date: 2006-01-18
Anticipated expiration: 2019-12-28
Also published as: JP2001185093A

Description

【０００１】
【発明の属する技術分野】
本発明は密閉形蓄電池、特にバックアップ用途等に用いられる大形の密閉形鉛蓄電池に関するものである。
【０００２】
【従来の技術】
バックアップ電源用の蓄電池として従来の液式の鉛蓄電池に代わって密閉形鉛蓄電池が広く使用されてきている。密閉形鉛蓄電池は補液等の保守点検作業を低減することができるので運用コスト面で有利である。このような中で、近年縦長形状の密閉形鉛蓄電池が普及しつつある。この縦長形状の密閉鉛蓄電池は横置きの状態で多段積みにして使用される。このような設置方法によれば設置高さを高くしても電池の端子は組電池の側面に位置するので端子間の配線作業や日常の保守点検作業の作業性を損なうことがない。また、設置高さを高くできるので設置に必要な面積は従来の液式鉛蓄電池に比較して少なくできるという利点がある。
【０００３】
一方、密閉形鉛蓄電池の電槽内圧は製造工程および市場で使用される際に加圧、減圧の変化を繰り返す。この圧力の変化によって電槽の側面、底面は、加圧の時は凸に変形し、減圧の時は凹に変形する。このような変形は小形の密閉形鉛蓄電池ではそれほど問題ではなかった。ところが大容量の密閉形鉛蓄電池になると、電槽内壁の面積増加に伴って内圧上昇によって受ける力は増大する。また、特に縦長形状の電池においては大面積を有する側面にかかる大きな応力は比較的小面積である底面との狭い境界部に集中することになる。このような応力は常時同一方向に作用するのではなく、前記したような電槽内圧の変化と大気圧との関係により応力の方向は変化する。すなわち、側面が底面との境界部をヒンジとして側面と底面とのなす角度が変化するように変形する。このような変形は特に底辺の一方の外寸をａ、底辺の他の一方の外寸をｂ、そしてこの辺に接する側面の高さ、すなわち電槽の高さ方向の外寸ｈとした場合にｈ≧１．４ａ、ｈ≧１．４ｂの場合に特に顕著である。このような変形は電槽側面と底面との境界部にクラックを発生させることがある。このようなクラックにより電槽の気密が損なわれて蓄電池容量が低下したり、電解液が一部電槽外へ漏出するという課題があった。
【０００４】
【発明が解決しようとする課題】
本発明は前記したような密閉形蓄電池において、電槽内圧の変化によって電槽側面と底面との間の境界部に生じるクラックを抑制して信頼性に優れた密閉形蓄電池を得ることを目的とする。
【０００５】
【課題を解決するための手段】
前記課題を解決するため、本発明の請求項１記載に係る発明はエチレン−プロピレンブロック共重合体を主体とする合成樹脂からなる電槽を備えた密閉形蓄電池において、前記電槽の側面と底面との境界部に小空孔のミクロボイドを電槽の他の部分に比較して多く存在させた。
【０００６】
また、本発明の請求項２記載に係る発明は請求項１の構成を有する密閉形蓄電池において、電槽の高さ方向の外寸をｈ、底辺の一方の外寸をａ、底辺の他の一方の外寸をｂとした時にｈ≧１．４ａでかつｈ≧１．４ｂとしたものである。
【０００７】
また、本発明の請求項３記載に係る発明は請求項２の構成を有する密閉形蓄電池において、電槽は一つのセル室から構成することとした。
【０００８】
また、本発明の請求項４記載に係る発明は請求項２または請求項３の構成を有する密閉形蓄電池において、電槽の高さ方向の外寸ｈは少なくとも４００ｍｍ以上とした。
【０００９】
また、本発明の請求項５記載に係る発明はエチレン−プロピレンブロック共重合体を主体とする合成樹脂からなる電槽を備えた密閉形蓄電池の製造方法であって、電槽底面もしくは電槽側面に変形を与えて前記底面と前記側面との境界部にミクロボイドの集中的な発生による白色部を形成する蓄電池の製造方法とした。
【００１０】
【発明の実施の形態】
以下に本発明の実施の形態について記載する。
【００１１】
まず、電槽材料としてはエチレン−プロピレンブロック共重合体を用いる。このエチレン−プロピレンブロック共重合体は樹脂成形機により縦長電槽に成形される。この後、電槽側面と底面との境界部に、ある一定以上の衝撃を加える。エチレン−プロピレンブロック共重合体に、ある一定以上の衝撃を加えると樹脂材料中に分散したエチレンプロピレンラバー中もしくはエチレンプロピレンラバー中に残留するポリエチレンとの境界部にミクロボイドと云われる小空孔が発生する。このミクロボイドは非常に径が小さく１０^-3から１０^-7ｍｍレベルのものである。このようなミクロボイドが発生した部分はヒンジ効果が発生し、繰り返しの変形によっても破断を発生させる確率を極めて低下させることが可能となる。実際にミクロボイドを発生させる手段としては、電槽を成形する際に成形機から電槽を取り出す過程、もしくは取り出した直後で電槽が雰囲気温度まで冷却される以前に、電槽の開口部から強制的に適度な圧力の変化を加えて適度に電槽側面、底面を変形させ、電槽側面、底面の周囲コーナー部にミクロボイドを形成させる。
【００１２】
このようなミクロボイドが発生した場合にはミクロボイドによって光散乱が起こるので、ミクロボイドが集中的に発生した部位は電槽の他の部位に比較して白く観察され、ミクロボイドの発生の有無を容易に判別することができる。
【００１３】
ここで電槽の形状としては電槽の高さ方向の外寸をｈ、底辺の一方の外寸をａ、底辺の他の一方の外寸をｂとした時に、ｈ≧１．４ａでかつｈ≧１．４ｂの縦長形状を有する電槽に適用することが特に望ましい。縦長形状を有しない電槽の場合は比較的長い電槽側面と底面との境界部が電槽側面の変形応力を受けるので比較的クラックを発生させることが少なく、結果として本発明の課題自体が縦長形状の電槽の場合ほどには顕著ではない。また、同様の理由により電槽の高さ方向の外寸ｈが４００ｍｍ以下の場合よりも、ｈが少なくとも４００ｍｍ以上となる場合に適用することが望ましい。
【００１４】
さらには、電槽が単一セルで構成される場合にはセルの側面の変形を抑制する隣接セルが存在しないので側面の変形は比較的自由に発生する。したがって本発明の課題がより顕著に発生することから、複数セルの場合に比較して単一セルで構成される電槽に本発明の構成を適用することが特に好ましい。
【００１５】
【実施例】
（実施例１）
以下に本発明の実施例とその効果について説明する。
【００１６】
まず、前記した発明の実施の形態にしたがって密閉形鉛蓄電池用の電槽を作製した。この電槽１は図１に示したように単セルで構成され、縦長形状を有しており底面２の外寸はａ＝３１８ｍｍ、ｂ＝１７０ｍｍである。電槽蓋との接合部までの電槽の高さはｈ＝４８０ｍｍであり、（ｈ／ａ）＝１．５１でかつ（ｈ／ｂ）＝２．８２である。なお、電槽の肉厚は４ｍｍである。ミクロボイドの形成方法としては電槽成形型から電槽を抜き取る際に電槽内側と成形型との間にエアーを導入して加圧し、電槽の底面２を電槽の外側に加圧変形させた。この変形量は２０ｍｍであった。この時、電槽の側面３と底面２との間の境界部４は電槽の他の部位に比較して白色化しミクロボイドが多く形成されたことを示していた。
【００１７】
次に本発明による電槽１と同一樹脂材料で成型され、同一形状・寸法を有する比較例の電槽を作製した。この比較例の電槽は成型直後に電槽の底面に加圧しなかったものであり、電槽の側面と底面との境界部には白色化は発生していなかった。これは電槽の側面と底面との境界部にミクロボイドが集中的に発生していないことを示している。
【００１８】
この本発明による電槽と比較例による電槽を用いてそれぞれ２Ｖ１０００Ａｈの密閉形鉛蓄電池を作製し連続充電試験を行った。すなわち、試験環境温度を６０℃として２．３Ｖの一定電圧で２週間連続充電後、７２時間放置する。この連続充電と放置を繰り返し行い電槽の状態を確認した。この試験においては充電時には電槽内は大気圧以上に加圧され、放置中は負極板による酸素ガス吸収反応により大気圧以下に減圧される。このようにして電槽内圧を変化させた場合での電槽側面と電槽底面との境界面でクラック発生の有無を確認した。その結果を表１に示す。
【００１９】
【表１】

【００２０】
表１に示したように比較例の電池は１４ヵ月目にして電槽の側面と底面との境界部表面にクラックが発生し、１６ヵ月目ではクラックがさらに成長して電槽内の気密が損なわれていたので試験を停止した。一方、本発明の電池では２４ヵ月時点でも比較例の電池で発生したようなクラックは認められなかった。
【００２１】
（実施例２）
次に比較例の電池の電槽および本発明例の電池の電槽について電槽の高さをそれぞれ４４５ｍｍ（ｈ／ａ＝１．４）の場合と４１３ｍｍ（ｈ／ａ＝１．３０）の場合とに変化させて実施例１と同様な連続充電試験を行った。この試験については最大２４ヵ月とし、電槽にクラックが発生するまでの期間を確認した。その結果、ｈ／ａの値が１．４の場合には比較例の電槽では１８ヵ月目に微少なクラックの発生が見られた。一方、ｈ／ａ＝１．３０では２４ヵ月目で微少なクラックの発生が見られた。一方、本発明例の電槽を用いた場合には２４ヵ月時点ではクラックは発生しなかった。よってこの比率（ｈ／ａ）が１．４以上の電槽を有するものについて本発明の構成を適用することが特に好ましいことが確認できた。
【００２２】
（実施例３）
次に本発明の電槽および比較例の電槽について形状を変更したものを作製した。すなわち電槽の底面の寸法は一辺を２３０ｍｍの正方形状とし、電槽の高さｈを４５０ｍｍ、４００ｍｍ、３５０ｍｍ、３１０ｍｍと変化させて実施例１と実施例２と同様の実験を行った。その結果、電槽の高さｈが４００ｍｍ、３５０ｍｍの比較例の電槽を用いたものについては、ｈ／ａの値はそれぞれ１．７４、１．５２と前記した１．４以上であるにもかかわらずクラックが発生するまでの期間が２０ヵ月と大幅に伸びていた。さらにｈ／ａ＝１．３５である３１０ｍｍの比較例の電槽を用いたものについては２４ヵ月時点でクラックは全く発生していなかった。なお、本発明例の電池については２４ヵ月時点でもクラックは発生していなかった。この結果から比率（ｈ／ｂ）が１．４以上の領域であっても電槽の高さｈが４００ｍｍ以下となるとクラックの発生までの期間が長くなることが確認できた。よって本発明の構成はクラック発生までの期間が比較的短くなる電槽の高さ４００ｍｍ以上の電池に適用することにより、本発明の効果がより顕著となることが確認できた。
【００２３】
これら実施例１〜３の結果から電槽の高さｈと底辺の一方の長さａの比率ｈ／ａが１．４以上であるような縦長形状を有し、かつｈが４００ｍｍを超える大形電槽を使用する場合に本発明の課題が顕著に発生することから本発明はこのような場合に適用することが特に望ましいことが判る。
【００２４】
（実施例４）
実施例１での本発明例の電槽と比較例での電槽について電槽肉厚をそれぞれ３ｍｍ、４ｍｍおよび７ｍｍのものを作製し、実施例１と同様の連続充電試験を行った。その結果、電槽の肉厚をこの領域（３〜７ｍｍ）で変化させてもクラックが発生し始める時期に変化は見られなかった。ただし、気密が損なわれるに至る期間は肉厚を７ｍｍにすることにより比較例の電槽で２０ヵ月まで長くなることが確認できた。
【００２５】
【発明の効果】
前記に説明したように本発明の構成によれば、縦長形状を有する密閉形蓄電池で発生する側面と底面との間の境界部でのクラックの発生を抑制して信頼性に優れた電池を得ることができ、工業上、極めて有用である。
【図面の簡単な説明】
【図１】本発明による密閉形蓄電池の電槽を示す図
【符号の説明】
１電槽
２底面
３境界部
ａ底辺の一方の外寸
ｂ底辺の他の一方の外寸
ｃ電槽の高さ方向の外寸 [0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sealed storage battery, and particularly to a large sealed lead storage battery used for backup applications and the like.
[0002]
[Prior art]
As a storage battery for a backup power source, a sealed lead storage battery has been widely used in place of the conventional liquid lead storage battery. The sealed lead-acid battery is advantageous in terms of operation cost because it can reduce maintenance and inspection work such as replacement fluid. Under such circumstances, a vertically long sealed lead-acid battery has been spreading in recent years. This vertically long sealed lead-acid battery is used in a multi-stage stack in a horizontal state. According to such an installation method, even if the installation height is increased, the terminals of the battery are located on the side surface of the assembled battery, and therefore, the workability of wiring work between terminals and daily maintenance and inspection work is not impaired. Further, since the installation height can be increased, there is an advantage that the area required for installation can be reduced as compared with the conventional liquid lead acid battery.
[0003]
On the other hand, when the internal pressure of the sealed lead-acid battery is used in the manufacturing process and in the market, it repeatedly changes in pressure and pressure. Due to this change in pressure, the side and bottom surfaces of the battery case are deformed into a convex shape during pressurization and into a concave shape during decompression. Such deformation has not been a significant problem for small sealed lead-acid batteries. However, when a sealed lead-acid battery with a large capacity is used, the force received by the increase in internal pressure increases as the area of the inner wall of the battery case increases. In particular, in the case of a vertically long battery, a large stress applied to a side surface having a large area is concentrated on a narrow boundary portion with a bottom surface having a relatively small area. Such a stress does not always act in the same direction, but the direction of the stress changes depending on the relationship between the change in the internal pressure of the battery case and the atmospheric pressure as described above. That is, the side surface is deformed so that the angle between the side surface and the bottom surface changes with the boundary portion between the side surface and the bottom surface as a hinge. Such deformation is particularly when one outer dimension of the base is a, the other outer dimension of the base is b, and the height of the side surface in contact with this side, that is, the outer dimension h in the height direction of the battery case. This is particularly noticeable when h ≧ 1.4a and h ≧ 1.4b. Such deformation may cause cracks at the boundary between the battery case side surface and the bottom surface. Due to such cracks, there was a problem that the airtightness of the battery case was impaired and the capacity of the storage battery was reduced, or a part of the electrolyte solution leaked out of the battery case.
[0004]
[Problems to be solved by the invention]
It is an object of the present invention to provide a sealed storage battery excellent in reliability by suppressing cracks generated at the boundary between the battery case side surface and the bottom surface due to a change in the battery case internal pressure. To do.
[0005]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the invention according to claim 1 of the present invention is a sealed storage battery including a battery case made of a synthetic resin mainly composed of an ethylene-propylene block copolymer. There were many microvoids of small pores in the boundary with the other parts of the battery.
[0006]
Further, the invention according to claim 2 of the present invention is the sealed storage battery having the configuration of claim 1, wherein the outer dimension in the height direction of the battery case is h, one outer dimension of the bottom is a, and the other of the bottom is When one outer dimension is b, h ≧ 1.4a and h ≧ 1.4b.
[0007]
According to a third aspect of the present invention, in the sealed storage battery having the configuration of the second aspect, the battery case is composed of one cell chamber.
[0008]
According to a fourth aspect of the present invention, in the sealed storage battery having the configuration of the second or third aspect, the outer dimension h in the height direction of the battery case is at least 400 mm or more.
[0009]
The invention according to claim 5 of the present invention is a method for producing a sealed storage battery comprising a battery case made of a synthetic resin mainly composed of an ethylene-propylene block copolymer, the battery case bottom surface or the battery case side surface. The storage battery was manufactured by forming a white portion due to concentrated generation of microvoids at the boundary between the bottom surface and the side surface.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below.
[0011]
First, an ethylene-propylene block copolymer is used as a battery case material. This ethylene-propylene block copolymer is formed into a vertically long battery case by a resin molding machine. After that, a certain level of impact is applied to the boundary between the battery case side surface and the bottom surface. When a certain level of impact is applied to the ethylene-propylene block copolymer, small voids called microvoids are generated at the boundary between the ethylene propylene rubber dispersed in the resin material and the polyethylene remaining in the ethylene propylene rubber. To do. This microvoid has a very small diameter and a level of 10 ⁻³ to 10 ⁻⁷ mm. The portion where such microvoids are generated has a hinge effect, and it is possible to greatly reduce the probability of occurrence of breakage even by repeated deformation. As a means of actually generating microvoids, the process of removing the battery case from the molding machine when forming the battery case, or immediately after taking out, is forced from the opening of the battery case before the battery case is cooled to the ambient temperature. A moderate pressure change is applied to deform the battery case side surface and bottom surface to form microvoids at the corners around the battery case side surface and bottom surface.
[0012]
When such microvoids occur, light scattering occurs due to the microvoids, so the area where the microvoids are concentrated is observed as white compared to other parts of the battery case, and the presence or absence of microvoids can be easily identified. can do.
[0013]
Wherein the battery case of the container as the shape in the height direction of the external dimensions h, and one of the outer dimensions of the base a, the other one of the outer dimensions of the base when is b, and at h ≧ 1.4a It is particularly desirable to apply to a battery case having a vertically long shape of h ≧ 1.4b. In the case of a battery case that does not have a vertically long shape, the boundary between the battery case side surface and the bottom surface that is relatively long is subjected to the deformation stress of the battery case side surface, so that it is relatively less likely to generate cracks. It is not as prominent as in the case of a vertically long battery case. For the same reason, it is desirable to apply when h is at least 400 mm, rather than when the outer dimension h in the height direction of the battery case is 400 mm or less.
[0014]
Furthermore, when the battery case is composed of a single cell, there is no adjacent cell that suppresses the deformation of the side surface of the cell, so that the side surface deformation occurs relatively freely. Therefore, since the subject of the present invention occurs more remarkably, it is particularly preferable to apply the configuration of the present invention to a battery case composed of a single cell as compared with the case of a plurality of cells.
[0015]
【Example】
Example 1
Examples and effects of the present invention will be described below.
[0016]
First, a battery case for a sealed lead-acid battery was produced according to the embodiment of the invention described above. As shown in FIG. 1, the battery case 1 is composed of a single cell and has a vertically long shape. The outer dimensions of the bottom surface 2 are a = 318 mm and b = 170 mm. The height of the battery case up to the junction with the battery case cover is h = 480 mm, (h / a) = 1.51 and (h / b) = 2.82. The wall thickness of the battery case is 4 mm. As a microvoid formation method, when the battery case is extracted from the battery case mold, air is introduced and pressurized between the inside of the battery case and the mold, and the bottom surface 2 of the battery case is pressurized and deformed to the outside of the battery case. It was. The amount of deformation was 20 mm. At this time, the boundary portion 4 between the side surface 3 and the bottom surface 2 of the battery case became whiter than other portions of the battery case, indicating that many microvoids were formed.
[0017]
Next, the battery case of the comparative example which was shape | molded with the same resin material as the battery case 1 by this invention, and has the same shape and a dimension was produced. The battery case of this comparative example was not pressurized on the bottom surface of the battery case immediately after molding, and no whitening occurred at the boundary between the side surface and the bottom surface of the battery case. This indicates that microvoids are not intensively generated at the boundary between the side surface and the bottom surface of the battery case.
[0018]
Using the battery case according to the present invention and the battery case according to the comparative example, 2V1000Ah sealed lead-acid batteries were produced and subjected to a continuous charge test. That is, the test environment temperature is set to 60 ° C. and the battery is continuously charged at a constant voltage of 2.3 V for 2 weeks and then left for 72 hours. This continuous charging and leaving was repeated to confirm the state of the battery case. In this test, the inside of the battery case is pressurized to atmospheric pressure or higher during charging, and is depressurized to atmospheric pressure or lower by oxygen gas absorption reaction by the negative electrode plate during standing. Thus, the presence or absence of the crack generation | occurrence | production was confirmed in the interface of a battery case side and a battery case bottom in the case of changing a battery case internal pressure. The results are shown in Table 1.
[0019]
[Table 1]

[0020]
As shown in Table 1, in the battery of the comparative example, cracks occurred on the surface of the boundary between the side surface and the bottom surface of the battery case at the 14th month, and the cracks further grew and the airtightness in the battery case was reduced at the 16th month. The test was stopped because it was damaged. On the other hand, in the battery of the present invention, no cracks occurred in the battery of the comparative example even at 24 months.
[0021]
(Example 2)
Next, regarding the battery case of the battery of the comparative example and the battery case of the example of the present invention, the height of the battery case is 445 mm (h / a = 1.4) and 413 mm (h / a = 1.30), respectively. A continuous charge test similar to that in Example 1 was performed. This test was performed for a maximum of 24 months, and the period until cracking occurred in the battery case was confirmed. As a result, when the value of h / a was 1.4, in the battery case of the comparative example, generation of minute cracks was observed at the 18th month. On the other hand, when h / a = 1.30, minute cracks were observed at the 24th month. On the other hand, when the battery case of the example of the present invention was used, no crack occurred at 24 months. Therefore, it was confirmed that it is particularly preferable to apply the configuration of the present invention to a battery having a ratio (h / a) of 1.4 or more.
[0022]
Example 3
Next, what changed the shape about the battery case of this invention and the battery case of a comparative example was produced. That is, the same experiment as in Example 1 and Example 2 was performed by changing the size of the bottom of the battery case to a square shape having a side of 230 mm and changing the height h of the battery case to 450 mm, 400 mm, 350 mm, and 310 mm. As a result, in the case where the battery case height h is 400 mm and 350 mm using the comparative battery case, the h / a values are 1.74 and 1.52, respectively, and 1.4 or more as described above. Regardless, the period until cracking has increased significantly to 20 months. Furthermore, no cracks occurred at 24 months in the case of using the 310 mm comparative battery case where h / a = 1.35. In the batteries of the present invention, no cracks occurred even at 24 months. From this result, it was confirmed that even when the ratio (h / b) was 1.4 or more, if the height h of the battery case was 400 mm or less, the period until the occurrence of cracking was increased. Therefore, it was confirmed that the effect of the present invention becomes more remarkable when the configuration of the present invention is applied to a battery having a battery case height of 400 mm or more in which the period until crack generation is relatively short.
[0023]
From the results of Examples 1 to 3, the battery case has a vertically long shape in which the ratio h / a of the height h of the battery case to the length a of the bottom side is 1.4 or more, and h is large exceeding 400 mm. Since the subject of the present invention is remarkably generated when using a battery case, it can be understood that the present invention is particularly preferably applied in such a case.
[0024]
(Example 4)
With respect to the battery case of the present invention example in Example 1 and the battery case in the comparative example, those having thicknesses of 3 mm, 4 mm, and 7 mm, respectively, were prepared, and the same continuous charging test as in Example 1 was performed. As a result, even when the thickness of the battery case was changed in this region (3 to 7 mm), no change was observed when cracks started to occur. However, it was confirmed that the period until the airtightness was lost was increased to 20 months in the battery case of the comparative example by setting the thickness to 7 mm.
[0025]
【The invention's effect】
As described above, according to the configuration of the present invention, a battery having excellent reliability can be obtained by suppressing the occurrence of cracks at the boundary between the side surface and the bottom surface generated in the sealed storage battery having a vertically long shape. It is extremely useful industrially.
[Brief description of the drawings]
FIG. 1 is a diagram showing a battery case of a sealed storage battery according to the present invention.
DESCRIPTION OF SYMBOLS 1 Battery case 2 Bottom face 3 Boundary part a One outer dimension of the bottom side b The other outer dimension of the bottom side c The outer dimension of the height direction of the battery case

Claims

In a sealed storage battery including a battery case made of a synthetic resin mainly composed of an ethylene-propylene block copolymer, microvoids of small pores are formed in other parts of the battery case at the boundary between the side surface and the bottom surface of the battery case. A sealed storage battery characterized in that a large amount is present in comparison.

The height direction of the outer dimensions of the battery container h, and one of the outer dimensions of the base a, the other one of the outer dimensions of the base when is b, it was h ≧ 1.4a a and h ≧ 1.4b The sealed storage battery according to claim 1.

The sealed battery according to claim 2, wherein the battery case is composed of one cell chamber.

4. The sealed storage battery according to claim 2, wherein h is at least 400 mm or more.

A method for producing a sealed storage battery comprising a battery case made of a synthetic resin mainly composed of an ethylene-propylene block copolymer, wherein a boundary is formed between the bottom face and the side face by deforming the battery bottom face or the battery case side face. A method for producing a sealed storage battery, characterized in that a white part is formed in the part due to intensive generation of microvoids.