JP4473411B2 - Sealed secondary battery - Google Patents

Description

実施例１〜１０の電池では、各実施例とも２０個全てがガスバーナーで加熱中に防爆弁が作動し、電池内で発生したガスを噴出させて放出することで試験は収束した。それに対して、比較例１〜４の電池では、ガスバーナーで加熱中に防爆弁が作動したものの、ガスの噴出による放出が十分でなく、２０個の内、半数以上は破裂する電池が存在した。
【００４５】
したがって、本発明の密閉二次電池はいずれも防爆弁が設定通りに作動していることが確認できた。
【００４６】
以上に説明したように、本発明の密閉二次電池は、防爆弁が所望の圧力で開口するように形成されているので、電池内部のガス発生により内圧が所定値以上に上昇すると、密閉二次電池の外装缶の所定位置に設けた防爆弁が作用して、過充電時などの密閉二次電池の内圧上昇や発熱を初期で抑えることができる。
【００４７】
また、防爆弁により発生したガスを円滑に電池の外部に排出して密閉二次電池の破裂を確実に防止することができる。
【００４８】
【発明の効果】
本発明によれば、防爆弁の作動を所定範囲内に確実に限定した、極めて安全性の高い密閉二次電池が得られる。
【図面の簡単な説明】
【図１】本発明にかかわる密閉二次電池の斜視図。
【図２】本発明にかかわる外装缶の斜視図。
【図３】本発明にかかわる外装缶の防爆弁の位置の説明図。
【図４】（ａ）〜（ｃ）は防爆弁の形状の説明図。
【図５】本発明の実施例を示す防爆弁の形状と位置の説明図。
【図６】本発明の実施例を示す防爆弁の形状と位置の説明図。
【図７】本発明の実施例を示す防爆弁の形状と位置の説明図。
【図８】本発明の実施例を示す防爆弁の形状と位置の説明図。
【図９】本発明の実施例を示す防爆弁の形状と位置の説明図。
【図１０】本発明の実施例を示す防爆弁の形状と位置の説明図。
【図１１】本発明の実施例を示す防爆弁の形状と位置の説明図。
【図１２】本発明の実施例を示す防爆弁の形状と位置の説明図。
【図１３】本発明の実施例を示す防爆弁の形状と位置の説明図。
【図１４】本発明の実施例を示す防爆弁の形状と位置の説明図。
【図１５】本発明の比較例を示す防爆弁の形状と位置の説明図。
【図１６】本発明の比較例を示す防爆弁の形状と位置の説明図。
【図１７】本発明の比較例を示す防爆弁の形状と位置の説明図。
【図１８】本発明の比較例を示す防爆弁の形状と位置の説明図。
【図１９】従来の防爆弁の説明図。
【図２０】従来の防爆弁の説明図。
【図２１】従来の防爆弁の説明図。
【符号の説明】
１…外装缶、２…、３…電極体、１６…側壁、１８、１８ａ〜１８ｎ…防爆弁、１９…開口部、２０…底部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a secondary battery of a rectangular metal outer can in which an explosion-proof valve is formed on one surface or a plurality of surfaces of the outer can, and in particular, has a highly safe explosion-proof function that operates accurately against abnormal situations. The present invention relates to a sealed secondary battery.
[0002]
[Prior art]
In recent years, there has been a remarkable increase in performance and size of electronic devices such as mobile phones and notebook computers, and the demand for higher energy secondary batteries serving as power sources for these electronic devices has also increased. For this reason, development of a sealed secondary battery that uses a material capable of absorbing and releasing lithium, such as lithium metal, lithium alloy, or carbonaceous material, as an anode material has been actively conducted.
[0003]
However, there is a concern about a decrease in safety as the energy of the battery increases. For example, a sealed secondary battery using a non-aqueous electrolyte may be overcharged due to excessive current being supplied at the time of charging, or it may be damaged due to equipment failure or misuse. When a large current flows and the battery is short-circuited, the electrolytic solution in the battery is decomposed to generate gas and the internal pressure of the battery increases, and the battery may burst.
[0004]
Furthermore, if overcharging or short-circuiting in the battery continues, the temperature of the battery suddenly rises due to heat generated by the decomposition of the electrolyte, and the battery may burst.
[0005]
Therefore, it is indispensable for practical use when it is desired to use a sealed secondary battery, in particular, a non-aqueous electrolyte solution, to prevent the battery from rising due to an increase in internal pressure or heat generation. For this reason, a sealed battery having a sealing structure having an explosion-proof function and a current interruption function as disclosed in JP-A-2-288063 has been put into practical use.
[0006]
In addition, there is a battery in which an explosion-proof valve formed of a thin-walled portion is formed on the outer can itself without using a battery sealing structure having an explosion-proof structure and a current blocking function.
[0007]
An example of them, symmetrically to the center line L ₁ -L ₂ on the bottom surface 32 of the bottom surface of the metallic outer can 31, as shown in FIG. 19, and explosion-proof valve 33a forming the thin portion in the lateral direction, in FIG. 20 as shown, symmetrically to the center line L ₃ -L ₄ of the side wall surface on the side wall 34 of the outer can 31, an explosion-proof valve 33b forming the thin portions in the transverse direction. In this case, as shown in FIG. 21, in the shape processing of the tip portions at both ends of the explosion-proof valve 33b, the remaining portion 36 is formed in a square shape with a corner.
[0008]
[Problems to be solved by the invention]
However, the sealing structure having the explosion-proof function and the current interruption function as described above is not preferable in terms of manufacturing because the structure is complicated and the number of parts to be configured is increased, and the number of parts is increased in assembling the battery.
[0009]
Also, the reason why the explosion-proof valve is formed on the bottom surface of the outer can is that the thickness of the bottom surface has become extremely small as recently developed, and the explosion-proof valve is physically formed. It has become difficult.
[0010]
In addition, it is desirable to install the explosion-proof valve at a location where the strength of the outer can is weakest. Each ridge line of the outer can is strong, and the thickness of the outer can is formed such that the bottom surface is thicker than the side wall, and the area of the bottom surface is smaller than each surface of the side wall. For this reason, providing an explosion-proof valve on the bottom surface of an outer can having a small area is not very advantageous from that point of view.
[0011]
In addition, the explosion-proof valve provided in a straight line parallel to the opening symmetrical to the center line of the side wall of the outer can is an appropriate position as an explosion-proof valve because the strength of the outer can is weak. However, it is desirable to reduce the pressure at which the explosion-proof valve operates from the viewpoint of safety. To cope with this, it is necessary to make the thin part of the explosion-proof valve thin, but there is a physical limit to this, It becomes difficult to form an explosion-proof valve. Even if an extremely thin plate corresponding to that is machined and an explosion-proof valve with a low operating pressure is formed, the variation in operating pressure increases due to large variations in manufacturing errors because the plate thickness is thin. It is difficult to form a reliable explosion-proof valve.
[0012]
In addition, when the explosion-proof valve is formed symmetrically on the center line of the side wall of the outer can, the explosion position of the explosion-proof valve (the position where the same stress is applied at the end of the explosion-proof valve) becomes two points. Therefore, the burst timing may be delayed as compared with the case of one point. That is, when the rupture position is two points, the rupture points are dispersed at two points and the stress is not concentrated on one point, so that it may take time for the rupture points to reach the rupture stress level.
[0013]
The present invention has been made based on these circumstances, and a sealed secondary battery having an explosion-proof valve structure that is extremely safe and can easily change the operating pressure is used as an explosion-proof means for the sealed secondary battery. It is intended to provide.
[0014]
[Means for Solving the Problems]
According to the present invention, a metal rectangular outer can formed in a bottomed cylindrical shape with a side wall and a bottom, and a positive electrode and a negative electrode which are accommodated inside the outer can and opposed to each other with a separator interposed therebetween are spirally formed. In a sealed secondary battery having a wound electrode body and a non-aqueous electrolyte to be injected into the outer can, the opening of the outer can being sealed with a lid, the area of the side wall is wide An explosion-proof valve is formed on the side wall with a thinner part than other parts, and the straight part of the explosion-proof valve does not intersect the vertical or horizontal center line of the side wall when the outer can is in a standing position. Or at least a portion of the straight portion of the thin wall portion is asymmetrically intersecting each center line, and the outer can is in a standing state from the lateral ridge line of the side wall to the opposite ridge line side after 1 mm In the region from the ridge line to a position of 1/4 of the side wall height, One, wherein the outer can is formed in the region of the longitudinal edges of the side wall in upright position from the ridge line in 1mm after the opposite ridge side to the position of 1/6 of the side wall width It is a sealed secondary battery.
[0015]
According to the invention, the thin-walled portion is a sealed secondary battery in which the straight portion and the non-linear portions located at both ends of the straight portion are continuously formed .
[0019]
According to the present invention, in the sealed secondary battery according to any one of the above, the explosion-proof valve is formed by pressing.
[0020]
Further, according to the present invention, in the above sealed secondary battery, the outer can is made of any one material of aluminum, iron, stainless steel, and alloys thereof.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of a sealed secondary battery of the present invention will be described with reference to the drawings.
[0022]
First, the structure of a sealed secondary battery according to the present invention will be described in detail with reference to FIG. 1, taking a square sealed battery as an example. FIG. 1 is a perspective view showing a sealed secondary battery according to the present invention, for example, a square sealed lithium ion battery. Here, the square shape means that the cross-sectional shape when the outer can is cut on the surface including the power generation element is a rectangle, but each corner portion is formed in an R shape (curved surface). Including.
[0023]
That is, the outer can 1 having a bottomed rectangular tube shape made of aluminum or an aluminum alloy also serves as a positive electrode terminal. An insulating film 2 is disposed on the inner bottom surface of the outer can 1. Further, an explosion-proof valve (not shown), which will be described later, is formed on the long side surface 1a having a large area at the side wall portion of the outer can 1 by thin-wall processing. In the outer can, the long side surface 1a having a large area is the weakest portion in terms of strength, so the explosion-proof valve is provided on the long side surface 1a.
[0024]
The electrode body 3 that is a power generation element is housed inside the outer can 1. The electrode body 3 is formed by winding the negative electrode 4, the separator 5, and the positive electrode 6 in a spiral shape so that the positive electrode 6 is located on the outermost periphery, and then press-molding it into a flat shape. A spacer 7 made of, for example, a synthetic resin having a lead extraction hole near the center is disposed on the electrode body 3 inside the outer can 1. The lid body 8 made of aluminum or an aluminum-based alloy and provided with a liquid injection hole 10 and a negative terminal take-out hole (not shown) is airtightly joined to the upper end opening of the outer can 1 by, for example, laser welding. Note that injection hole 10 after pouring the electrolytic solution into the outer can 1, the inserted aluminum or aluminum-based alloy of the plug member into the injection hole 10 (not shown) is welded to the lid 8 by a pulse laser, The liquid injection hole 10 is sealed.
[0025]
The negative electrode terminal 11 is hermetically sealed in the take-out hole of the lid 8 via an insulator 12 made of glass or resin. Moreover, the wiring material 13 of the battery pack which is not shown in figure is joined to the exterior of these exterior can side walls.
[0026]
As shown in FIG. 2, the outer can 1 is formed by deep drawing a thin plate material of aluminum or aluminum alloy, the outer dimensions are 30 mm wide × 40 mm high × 5 mm thick, and the plate thickness is 0.25 mm to 0.00 mm. It is processed into a predetermined shape of a 40 mm bottomed rectangular cylinder. Thereafter, the explosion-proof valve 18 is pressed on the side wall 16. The explosion-proof valve 18 is processed by pressing a cross section as shown in FIG. 2 from the outside of the side wall 16 with a core (not shown) inserted through the opening 19 into the rectangular cylinder which is the outer can 1. ing.
[0027]
As shown in FIG. 2, the shape and position of the explosion-proof valves 18, 18 ₋₁ to 18 _-n are basically straight portions, which intersect with the center line AA ′ of the side wall of the outer can 1. position without, or center line a-A'and explosion-proof valve 18 - _{if 2,} 18 part of _-3 intersect are formed at positions intersecting asymmetrically.
[0028]
These explosion-proof valve _{18, 18} -1 _{~ 18 -n} position and shape, and the experiment of varying the thickness of the thin portion of the explosion-proof valve _{18, 18} -1 _{~ 18 -n,} sidewall centerline A-A of 'and by explosion-proof valve 18 is formed at a position not intersecting, explosion-proof valve 18 _-1, 18 _- without reducing the thickness of the thin portion of the _4, setting a low working pressure in the thin portion is thicker state be able to.
[0029]
In other words, an explosion-proof valve ₁₈ -1, 18 _- by leaving thick thin portion as _4, the processing of the thin portion becomes easy, even less variation in processing. Thus, explosion-proof valve 18 _-1, 18 _- working pressure as ₄ is easily controlled, also, it is possible to suppress variations in operating pressure within a certain narrowest range. Therefore, safety and reliability of the very high explosion-proof valve ₁₈ -1, 18 _{- 4} form a.
[0030]
Further, explosion-proof valve 18 _-2, 18 _{- 3} when partially intersects with the center line A-A'extend of the rupture position of the explosion-proof valve (at the end of the explosion-proof valve, the same stress is applied position) There will be one point, explosion-proof valve ₁₈ -2, 18 _{- 3} of the operation can be accurately controlled.
[0031]
As shown in FIG. 3, the position of the explosion-proof valve 18 is 1 mm below the ridgeline of the opening 19 of the outer can 1 (the ridgeline in the lateral direction when the outer can 1 is in a standing position) or by the experiment. Positioned at ¼ of the length from the parallel straight line located 1 mm above the ridgeline of the bottom 20 of the can 1 and the ridgeline of the opening 19 or the ridgeline of the bottom 20 to the ridgeline of the opening 19 to the ridgeline of the bottom 20 A region surrounded by a straight line parallel to the ridgeline of the opening end 19 and a ridgeline perpendicular to the ridgeline of the opening 19 (a ridgeline in the vertical direction with the exterior can 1 in a standing position) and a straight line located 1 mm The explosion-proof valve 18 is processed in a region surrounded by a straight line parallel to the ridge line that is 1/6 of the length to the opposite ridge line and at a position that does not intersect the center line A-A ′. It was confirmed that it was suitable.
[0032]
However, when only a part of the explosion-proof valve 18 is formed to extend to a region within 1 mm from each ridgeline, or only a part of the explosion-proof valve 18 intersects the center line A-A ′, It has been confirmed that similar results can be obtained.
[0033]
It has also been confirmed that the position of the explosion-proof valve 18 with respect to the center line A-A ′ is completely the same even when the outer can 1 is turned over. That is, in this case, the center line A-A ′ relating to the position of each explosion-proof valve 18 described above is read as the center line BB ′, and each ridge line becomes a ridge line perpendicular to the ridge line described above.
[0034]
This position is confirmed by checking that the sealed secondary battery of the rectangular outer can 1 is inflated and deformed when the explosion-proof valve 18 is activated. It was experimentally confirmed that the most concentrated points were the area from the opening 19 and the bottom 20 to 1/4 of the battery height and the area from the ridge line perpendicular to the opening edge to 1/6 of the battery width. Based on confirmed results.
[0035]
In addition to the linear shape shown in FIG. 2, the explosion-proof valve may be formed in a shape as shown in FIGS. 4 (a), 4 (b) and 4 (c). Since the portions other than the explosion-proof valve are the same as those in FIG. 2, the same portions are denoted by the same reference numerals and the description thereof is omitted.
[0036]
The explosion-proof valve 18a shown in FIG. 4 (a) is changed in direction by an angle d toward the opening 19 of the outer can 1 at both ends of the linear portion. The angle d needs to be adjusted to an appropriate value depending on the size and shape of the outer can 1, but the range is preferably 0 to 90 degrees. Furthermore, it has been confirmed by experiments with different angles that the range of 25 to 45 degrees is more preferable. Moreover, the explosion-proof valve 18b shown in FIG.4 (b) forms the circular part in the both ends of a linear part. Furthermore, the explosion-proof valve 18c shown in FIG. 4 (c) is curved upward at both ends of the linear portion. The shape shown in FIGS. 4B and 4C is an opportunity for the explosion-proof valves 18a and 18b to tear beyond the desired dimensions and area by making the end portions of the explosion-proof valves 18a and 18b round with no corners. Has been significantly reduced.
[0037]
Therefore, in any of these shapes, when the explosion-proof valves 18a, 18b, and 18c are operated, the opening portions of the explosion-proof valves 18a, 18b, and 18c are opened beyond a predetermined size and area. It has the effect of preventing the contents such as the power generation element from being scattered outside the battery.
[0038]
Moreover, it was confirmed by experiment that the processing method of the explosion-proof valve had good workability by pressing. A production method by press working is most advantageous in terms of cost, and it is easy to control the operating pressure, but other methods using etching are also possible. However, the etching method is expensive and unsuitable for mass production.
[0039]
According to experiments, the same results were obtained with regard to the position of the explosion-proof valve even when iron or stainless steel was used as the outer can material in addition to aluminum or aluminum alloy.
[0040]
Next, examples of the explosion-proof valve of the present invention and comparative examples for the same will be described below.
[0041]
In each embodiment, as described above, a part of the explosion-proof valve extends and is formed so as to intersect with the longitudinal or lateral center line, or within an area within 1 mm from each ridgeline. Although the example in the case of being formed is not illustrated, it is attached to each example.
[0042]
Moreover, the illustration in each Example is 40 mm in height and 30 mm in width in any case. The explosion-proof valve is formed on the side wall (side wall having a large area) of the outer can, and the shape thereof includes a straight portion in the length direction, and the width is about 0.2 mm. Moreover, the straight part is provided in the position which does not cross | intersect the centerline of an exterior can side wall. The same functional parts as those in FIG.
Example 1
With the position and shape of the explosion-proof valve 18 d as shown in FIG. 5, the explosion-proof valve 18 d is formed by a linear portion parallel to the opening 19 of the outer can 1. The position of the explosion-proof valve 18d is provided at a position 1 mm from the opening 19 of the outer can 1.
(Example 2)
With the position and shape of the explosion-proof valve 18 e as shown in FIG. 6, the explosion-proof valve 18 e is formed by a linear portion parallel to the opening 19 of the outer can 1. The position of the explosion-proof valve 18e is provided at a position of 10 mm, which is a region within 1/4 of the height of the outer can 1 from the opening 19 of the outer can 1.
(Example 3)
With the position and shape of the explosion-proof valve 18 f as shown in FIG. 7, the explosion-proof valve 18 f is formed by a linear portion parallel to the bottom 20 of the outer can 1. The position of this explosion-proof valve is provided at a position of 10 mm, which is an area within 1/4 of the height of the outer can 1 from the bottom 20 of the outer can 1.
Example 4
The explosion-proof valve 18g has the position and shape as shown in FIG. 8, and the explosion-proof valve 18g is formed by a straight portion parallel to the ridge line perpendicular to the opening 19 of the outer can 1 and the straight portion is another center line of the side wall. It does not cross BB ′ and is provided at a position of 5 mm, which is a region within 1/6 of the width direction of the outer can 1.
(Example 5)
With the position and shape of the explosion-proof valve 18 h as shown in FIG. 9, the explosion-proof valve 18 h is formed by a straight portion having an angle of 45 degrees with respect to the opening 19 of the outer can 1. The end portion of the linear portion of the explosion-proof valve 18h extends over an area from 1 mm to 10 mm from the opening 19 of the outer can 1.
(Example 6)
With the position and shape of the explosion-proof valve 18 i as shown in FIG. 10, the explosion-proof valve 18 i is formed by a straight portion and has an angle of 45 degrees with respect to the opening 19 and 45 degrees with respect to the ridgeline of the side wall 16. And it is formed in the area | region which is 10 mm from the opening part 19 to the height of the armored can 1, and 5 mm from the ridgeline of the side wall 16 to the width direction.
(Example 7)
With the position and shape of the explosion-proof valve 18a as shown in FIG. 11, the explosion-proof valve 18a has the shape shown in FIG. 4A, and the explosion-proof valve 18a is inclined above both ends of the linear portion. The inclination angle is 45 degrees. The position of the explosion-proof valve 18a is formed in a region from 1 mm to 10 mm downward from the opening 19 of the outer can.
(Example 8)
The position and shape of the explosion-proof valve 18b as shown in FIG. 12, the explosion-proof valve 18b has the shape shown in FIG. 4 (b), the explosion-proof valve 18b is inclined above both ends of the linear portion, and a circular portion is formed at the inclined tip. Is forming. The tip is formed in an R shape. The explosion-proof valve 18b is formed in a region from 1 mm to 10 mm below the opening 19 of the outer can 1.
Example 9
The position and shape of the explosion-proof valve 18c as shown in FIG. 13, the explosion-proof valve 18c has the shape shown in FIG. 3C, and the explosion-proof valve 18c is formed in a semicircular shape at both ends of the straight line portion. The radius of curvature on the semicircle is about 15 mm to 25 mm. The explosion-proof valve 18c is formed in a region from 1 mm to 10 mm below the opening 19 of the outer can 1.
(Example 10)
The position and shape of the explosion-proof valve 18j as shown in FIG. 14, the explosion-proof valve 18j has the shape shown in FIG. 14, and the explosion-proof valve 18j has circular portions at both ends of the straight line portion. The radius of curvature of the circular portion is about 0.4 mm to 1.2 mm. The explosion-proof valve 18j is formed in a region from 1 mm to 10 mm below the opening 19 of the outer can 1.
(Comparative Example 1)
With the position and shape of the explosion-proof valve 18k as shown in FIG. 15, the explosion-proof valve 18k is formed by a straight portion parallel to the opening 19 of the outer can 1 and is symmetric with respect to the center line AA ′ of the outer can 1. Formed in position. The explosion-proof valve 18k is provided at a position 5 mm below the opening 19 of the outer can 1.
(Comparative Example 2)
With the position and shape of the explosion-proof valve 18 m as shown in FIG. 16, the explosion-proof valve 18 m is formed by a linear portion parallel to the opening 19 of the outer can 1. The explosion-proof valve 18 m is provided at a position 15 mm below the opening 19 of the outer can 1.
(Comparative Example 3)
With the position and shape of the explosion-proof valve 18n as shown in FIG. 17, the explosion-proof valve 18n is formed by a straight portion parallel to the ridgeline of the side wall 16 including the opening 19 and the bottom 20 of the outer can 1, and the width direction of the outer can 1 Is provided at a position of 6 mm from the ridgeline.
(Comparative Example 4)
With the position and shape of the explosion-proof valve 18p as shown in FIG. 18, the explosion-proof valve 18p is inclined downward at both ends of the linear portion. The inclination angle is 60 degrees. The explosion-proof valve 18p is provided in a region from 5 mm to 12 mm below the opening 19 of the outer can 1.
[0043]
In the above embodiment, the explosion-proof valve is formed on one surface of the side wall of the outer can, but the explosion-proof valve may be formed on each of the two surfaces of the side wall. In that case, the position of the explosion-proof valve in the two eyes is preferably an antisymmetric position with respect to the center line of the side wall.
[0044]
Next, the result of the safety test for each of the above-described examples and comparative examples will be described. In the safety test, about 20 square batteries of Examples 1 to 10 and Comparative Examples 1 to 3, the battery voltage was set to 4.2 V with the battery fully charged, and the battery was heated with a gas burner. The test was conducted. Table 1 shows the results.
[Table 1]

In each of the batteries of Examples 1 to 10, the explosion-proof valve actuated while all 20 were heated by a gas burner, and the test converged by ejecting and releasing the gas generated in the battery. On the other hand, in the batteries of Comparative Examples 1 to 4, although the explosion-proof valve was activated during heating with the gas burner, the release by gas ejection was not sufficient, and among the 20 batteries, more than half of the batteries bursted. .
[0045]
Therefore, it was confirmed that all of the sealed secondary batteries of the present invention had the explosion-proof valve operating as set.
[0046]
As described above, since the sealed secondary battery of the present invention is formed so that the explosion-proof valve opens at a desired pressure, when the internal pressure rises to a predetermined value or more due to gas generation inside the battery, the sealed secondary battery is sealed. An explosion-proof valve provided at a predetermined position of the outer battery can can act to suppress an increase in internal pressure and heat generation of the sealed secondary battery at the time of overcharging.
[0047]
Further, the gas generated by the explosion-proof valve can be smoothly discharged to the outside of the battery to reliably prevent the sealed secondary battery from bursting.
[0048]
【The invention's effect】
According to the present invention, it is possible to obtain an extremely safe sealed secondary battery in which the operation of the explosion-proof valve is surely limited within a predetermined range.
[Brief description of the drawings]
FIG. 1 is a perspective view of a sealed secondary battery according to the present invention.
FIG. 2 is a perspective view of an outer can according to the present invention.
FIG. 3 is an explanatory view of the position of an explosion-proof valve of an outer can according to the present invention.
4A to 4C are explanatory views of the shape of an explosion-proof valve. FIG.
FIG. 5 is an explanatory view of the shape and position of an explosion-proof valve showing an embodiment of the present invention.
FIG. 6 is an explanatory diagram of the shape and position of an explosion-proof valve according to an embodiment of the present invention.
FIG. 7 is an explanatory view of the shape and position of an explosion-proof valve showing an embodiment of the present invention.
FIG. 8 is an explanatory view of the shape and position of an explosion-proof valve showing an embodiment of the present invention.
FIG. 9 is an explanatory view of the shape and position of an explosion-proof valve showing an embodiment of the present invention.
FIG. 10 is an explanatory diagram of the shape and position of an explosion-proof valve showing an embodiment of the present invention.
FIG. 11 is an explanatory view of the shape and position of an explosion-proof valve showing an embodiment of the present invention.
FIG. 12 is an explanatory view of the shape and position of an explosion-proof valve showing an embodiment of the present invention.
FIG. 13 is an explanatory view of the shape and position of an explosion-proof valve showing an embodiment of the present invention.
FIG. 14 is an explanatory diagram of the shape and position of an explosion-proof valve according to an embodiment of the present invention.
FIG. 15 is an explanatory view of the shape and position of an explosion-proof valve showing a comparative example of the present invention.
FIG. 16 is an explanatory diagram of the shape and position of an explosion-proof valve showing a comparative example of the present invention.
FIG. 17 is an explanatory diagram of the shape and position of an explosion-proof valve showing a comparative example of the present invention.
FIG. 18 is an explanatory diagram of the shape and position of an explosion-proof valve showing a comparative example of the present invention.
FIG. 19 is an explanatory diagram of a conventional explosion-proof valve.
FIG. 20 is an explanatory diagram of a conventional explosion-proof valve.
FIG. 21 is an explanatory diagram of a conventional explosion-proof valve.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Exterior can, 2 ... 3 ... Electrode body, 16 ... Side wall, 18, 18a-18n ... Explosion-proof valve, 19 ... Opening, 20 ... Bottom

Claims (4)

A metal rectangular outer can formed in a bottomed cylindrical shape with a side wall and a bottom, and an electrode body housed inside the outer can and wound in a spiral shape with a positive electrode and a negative electrode facing each other across a separator And a non-aqueous electrolyte injected into the outer can, and in a sealed secondary battery in which the opening of the outer can is sealed with a lid,
Of the side walls, an explosion-proof valve is formed on the side wall having a larger area than the other part, and the straight part of the explosion-proof valve is in the vertical or horizontal direction of the side wall when the outer can is in a standing state. Does not intersect the center line of the direction, or intersects each center line asymmetrically ,
At least a part of the straight portion of the thin wall portion extends from the ridge line to a position ¼ of the side wall height after 1 mm from the lateral ridge line of the side wall to the opposite ridge line side in a state where the outer can is standing. In the region, the outer can is formed in the region from the vertical ridge line of the side wall to the opposite ridge line side after 1 mm from the ridge line to the position of 1/6 of the side wall width in the standing state . Sealed secondary battery characterized by. The sealed secondary battery according to claim 1 , wherein the thin portion is formed by continuously forming the straight portion and non-linear portions located at both ends of the straight portion . The sealed secondary battery according to claim 1, wherein the explosion-proof valve is formed by press working . The sealed secondary battery according to claim 1, wherein the outer can is made of any one material of aluminum, iron, stainless steel, and alloys thereof .

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