JP2020013692A - Secondary battery - Google Patents

Abstract

To provide a secondary battery which allows stable operation of a current interruption mechanism.SOLUTION: A secondary battery comprises: a battery case having an opening; an electrode body including a positive electrode and a negative electrode; a collector electrically connected to the positive electrode or the negative electrode; a sealing plate for sealing the opening; an external terminal fitted to the sealing plate; a conductive member electrically connected to the external terminal and having an opened portion at an electrode body side; and a deformation plate which hermetically seals the opened portion and is connected to the collector, and which is deformed when a pressure inside the battery case becomes equal to or higher than a predetermined value. The collector has a thin part 15 which has a recessed shape and breaks when the deformation plate is deformed. The thin part has: a bottom face 81 which is a bottom of the recessed shape; two lateral faces 82 and 83 which individually connect one end 91 and the other end 92 of the bottom face to an outer edge of the thin part. A thickness a at the one end of the bottom face is thinner than a thickness b at the other end of the bottom face. The other end of the bottom face is located closer to a connecting portion with the deformation plate than the one end of the bottom face.SELECTED DRAWING: Figure 8

Description

  The present invention relates to a secondary battery.

  Power supply for driving electric vehicles (EV) and hybrid electric vehicles (HEV, PHEV), applications for suppressing output fluctuations such as solar power generation and wind power generation, and system power for storing power at night and using it during the day Alkaline secondary batteries and non-aqueous electrolyte secondary batteries are used in stationary storage battery systems for peak shift applications.

  In a battery used for such an application, for example, as shown in Patent Literature 1 below, not only is a gas exhaust valve provided to release the internal pressure when the pressure inside the battery casing increases, but also an external terminal and A current cutoff mechanism for cutting off electrical connection with an electrode body inside the exterior body is provided.

JP 2018-41678 A

  The current interruption mechanism employs a structure in which a groove-shaped notch is provided in a current collector welded to a deformed plate, as in the technique disclosed in Patent Document 1, for example. In this structure, when the internal pressure of the battery case increases and the deformed plate is deformed, the notch breaks and cuts off the electrical connection between the external terminal and the electrode body.

  The current cutoff mechanism operates as described above, but it is important that, when manufacturing a large number of batteries, the current cutoff mechanism operates stably when a predetermined pressure value is reached in the battery case. It is. The present inventor has found that the variation in the operating pressure of the current interrupting mechanism can be reduced by devising the shape of the notch portion when the study for reducing the variation in the operating pressure of the current interrupting mechanism is performed.

  The present invention has been made in view of such a point, and an object of the present invention is to reduce the variation in the operating pressure of the current cutoff mechanism and to make the current cutoff mechanism operate stably in any battery. Is to provide.

  The secondary battery of the present invention has a battery case having an opening, an electrode body containing a positive electrode and a negative electrode housed in the battery case, a current collector electrically connected to the positive electrode or the negative electrode, and the opening. A sealing plate for sealing, an external terminal attached to the sealing plate, located between the sealing plate and the electrode body, electrically connected to the external terminal, and having an opening on the electrode body side. A conductive member, and a deformation plate that seals the opening portion, is connected to the current collector, and deforms when a pressure in the battery case becomes a predetermined value or more. A thin portion which is shaped and is provided with a thin portion which is broken when the deformable plate is deformed, and in a cross section cut along the thickness direction of the current collector, the thin portion is a bottom surface which is the bottom of the concave shape. Part, one end of the bottom part and one of the thin parts A first side portion connecting the edge and a second side portion connecting the other end portion and the other outer edge of the thin portion, and the thickness a of the bottom portion at the one end portion is The thickness of the bottom surface at the other end is smaller than the thickness b, and the other end is provided at a position closer to the connection portion with the deformable plate than the one end. ing.

  The thin portion preferably has a groove shape surrounding a portion where the deformable plate and the current collector are connected.

  The distance c between the one end and the other end may be greater than the thickness a of the bottom surface at the one end.

  The thickness a of the bottom surface at the one end may be not less than の and not more than 9/10 of the thickness b of the bottom surface at the other end.

  In the thickness a of the bottom surface at the one end, the thickness b of the bottom surface at the other end, and the distance c between the one end and the other end, (ba−c) / c May be 0.17 or more and 0.58 or less.

  In the secondary battery of the present invention, the thin portion that is broken by the deformation of the deformed plate has a bottom portion and two side portions, and the thickness of the bottom portion is different at a boundary portion between the two side portions, so that current is interrupted. Variations in the operating pressure of the mechanism can be suppressed.

FIG. 2 is a schematic front view showing the inside of the battery with the battery case front part and the insulating sheet front part of the battery according to the embodiment removed. FIG. 2 is a schematic top view of the battery according to the embodiment. FIG. 2 is a schematic side view showing the inside of the battery on the positive electrode side with the battery case side surface (positive electrode side) and the insulating sheet side surface (positive electrode side) removed from the battery according to the embodiment. FIG. 2 is a schematic side view showing the inside of the battery on the negative electrode side of the battery according to the embodiment, from which the battery case side surface (negative electrode side) and the insulating sheet side surface (negative electrode side) have been removed. FIG. 2 is a schematic enlarged cross-sectional view of the vicinity of a positive electrode terminal, taken along a center line of an upper surface of the battery according to the embodiment in parallel with the front surface. FIG. 2 is a schematic enlarged cross-sectional view of the vicinity of the positive electrode terminal, which is cut along the center line of the positive electrode terminal in parallel with the side surface of the battery according to the embodiment. It is an expanded sectional view of the part shown by A of FIG. It is an expanded sectional view in the circle of FIG. It is a typical sectional view showing an example of the shape of the conventional thin part. It is an expanded sectional view in the circle of FIG. It is a typical sectional view showing another example of the shape of the conventional thin part. It is a typical sectional view showing an example of the shape of the thin part of other embodiments. It is an expanded sectional view in the circle of FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The description of the preferred embodiments below is merely exemplary in nature and is not intended to limit the invention, its applications, or its uses. In the following drawings, components having substantially the same function are denoted by the same reference numeral for simplification of description.

(Embodiment 1)
First, the secondary battery of Embodiment 1 will be described with reference to FIGS. The secondary battery of the present embodiment has a flat electrode body 110 in which a positive electrode plate and a negative electrode plate are wound via a separator (both not shown). The positive electrode plate constituting the positive electrode is coated with a positive electrode active material mixture on both sides of a positive electrode core body made of aluminum foil, dried and rolled, and then the aluminum foil is strip-shaped along one longitudinal direction at one end. It is manufactured by slitting it to be exposed. Further, the negative electrode plate constituting the negative electrode, the negative electrode active material mixture is applied to both surfaces of the negative electrode core body made of copper foil, dried and rolled, and then the copper foil is applied to one end along the longitudinal direction. It is manufactured by slitting so as to be exposed in a band shape.

  Then, the positive electrode plate and the negative electrode plate obtained as described above have a region where the portion where the positive electrode core of the positive electrode plate is exposed and the portion where the negative electrode core of the negative electrode plate is exposed do not overlap with the electrodes facing each other. The electrode body 110 is manufactured by stacking and winding such that they are shifted with a microporous separator made of polypropylene and polyethylene interposed therebetween. A positive electrode core exposed portion 141 is formed at one end of the electrode body 110 in the winding axis direction, and a negative electrode core exposed portion 140 is formed at the other end.

  The positive electrode core exposed portion 141 is electrically connected to a positive terminal 130 serving as an external terminal via the positive electrode current collector 10. The lead portion 14 of the positive electrode current collector 10 is connected to one outer surface of the positive electrode core exposed portion 141 by welding. The receiving member 143 of the positive electrode current collector 10 is connected to the other outer surface of the positive electrode core exposed portion 141 by welding. An insulating film having an opening is arranged between one outer surface of the positive electrode core exposed portion 141 and the lead portion 14 of the positive electrode current collector 10, and the positive electrode core exposed portion 141 and the positive electrode current collector are opened through the opening of the insulating film. The lead portion 14 of the body 10 is connected by welding. An insulating film 147 having an opening is arranged between the other outer surface of the positive electrode core exposed part 141 and the receiving member 143 of the positive electrode current collector 10, and the positive electrode core exposed part 141 and the positive electrode are exposed through the opening of the insulating film 147. The receiving member 143 of the current collector 10 is connected by welding. The receiving member 143 of the positive electrode current collector 10, the insulating film 147, and the insulating film disposed between one outer surface of the positive electrode core exposed portion 141 and the lead portion 14 of the positive electrode current collector 10 are essential components. Instead, they can be omitted.

  The positive electrode current collector 10 is electrically insulated from the sealing plate 120 by the first insulating member 50 and the second insulating member 150.

  The negative electrode core exposed portion 140 is electrically connected to a negative electrode terminal 132 as an external terminal via the negative electrode current collector 20. The lead portion 114 of the negative electrode current collector 20 is connected to one outer surface of the negative electrode core exposed portion 140 by welding. The receiving member 142 of the negative electrode current collector 20 is welded to the other outer surface of the negative electrode core exposed portion 140. An insulating film having an opening is disposed between one outer surface of the negative electrode core exposed portion 140 and the lead portion 114 of the negative electrode current collector 20, and the negative electrode core exposed portion 140 and the negative electrode current collector are opened through the opening of the insulating film. The lead portion 114 of the electric body 20 is connected by welding. An insulating film 146 having an opening is disposed between the other outer surface of the negative electrode core exposed portion 140 and the receiving member 142 of the negative electrode current collector 20, and the negative electrode core exposed portion 140 is formed through the opening of the insulating film 146. The receiving member 142 of the negative electrode current collector 20 is connected by welding. The receiving member 142 of the negative electrode current collector 20, the insulating film 146, and the insulating film disposed between one outer surface of the negative electrode core exposed portion 140 and the lead portion 114 of the negative electrode current collector 20 are essential components. Instead, they can be omitted.

  Further, the negative electrode current collector 20 is electrically insulated from the sealing plate 120 by the negative electrode side insulating member 52a.

  The positive terminal 130 and the negative terminal 132 are fixed to the sealing plate 120 via a terminal insulating member 152 and a terminal insulating member 154, respectively. In the secondary battery of the present embodiment, a pressure-sensitive current interrupting mechanism 200 is provided between the positive electrode and the positive electrode terminal 130.

  The electrode body 110 is housed in the bottomed cylindrical battery case 100 in a state where the periphery except the sealing plate 120 side is covered with a resin insulating sheet 161. The opening of the battery case 100 is sealed by a sealing plate 120. The sealing plate 120 is provided with an electrolyte injection hole 163. After injection, the electrolyte injection hole 163 is sealed with a sealing stopper. Further, the sealing plate 120 is provided with a gas discharge valve 162 that is opened when a gas pressure higher than the operating pressure of the current cutoff mechanism 200 is applied.

  Next, the current interrupting mechanism 200 will be described. The current interrupting mechanism 200 may be provided on either the positive electrode side or the negative electrode side. In the following, a description will be given assuming that it is provided only on the positive electrode side. In the current interrupting mechanism 200, the weak portion provided in a part of the current-carrying path is broken by a member near the weak portion being deformed due to an increase in the pressure in the battery case 100, so that the current is cut off. It works by the mechanism that it is done.

  As shown in FIGS. 5 and 6, the positive electrode terminal 130 has a through hole formed therein. The positive electrode terminal 130 is inserted into through holes formed in each of the terminal insulating member 152, the sealing plate 120, the second insulating member 150, and the conductive member 30. It is caulked so as to be pressed against the conductive member 30 and is integrally fixed to each other. Thus, the positive electrode terminal 130 is electrically connected to the conductive member 30 while being electrically insulated from the sealing plate 120 by the terminal insulating member 152 and the second insulating member 150. Although not shown in the drawings, in FIGS. 5 and 6, an electrode body exists on the opposite side of the sealing member 120 with respect to the second insulating member 150 of all the illustrated components. It is preferable that the tip of the positive electrode terminal 130 on the inside of the battery and the connection between the conductive member 30 are welded by laser welding or the like. The through-hole formed in the positive electrode terminal 130 is sealed by a rubber terminal plug 158 having a metal plate 159 provided on the upper end.

   The second insulating member 150 is disposed between the sealing plate 120 and the conductive member 30, and insulates the sealing plate 120 from the conductive member 30. The conductive member 30 has a tubular portion 32 having a substantially square cross section on the electrode body 110 side, and a connecting portion arranged in parallel with the sealing plate 120 is formed on the sealing plate 120 side. I have. Then, the positive electrode terminal 130 is inserted into a through hole provided in the conductive member 30.

  The opening of the cylindrical portion 32 of the conductive member 30 on the side of the electrode body 110 is sealed by the deformable plate 40. The distal end portion of the tubular portion 32 of the conductive member 30 and the periphery of the deformable plate 40 are welded. The deformation plate 40 is formed of a conductive material such as aluminum. When the pressure in the battery case 100 increases to a predetermined value or more, the deformable plate 40 is deformed so that the central portion of the deformable plate 40 approaches the sealing plate 120 side (outside of the battery). The positive electrode current collector 10 is connected to the surface of the deformable plate 40 on the electrode body 110 side. The positive electrode current collector 10 is preferably made of a metal, and is preferably made of aluminum or an aluminum alloy. As the positive electrode current collector 10, for example, a metal plate made of a metal plate such as aluminum by punching can be used. As described above, the energization path is formed in the order of the positive electrode of the electrode body 110, the positive electrode current collector 10, the deformable plate 40, the conductive member 30, and the positive electrode terminal 130.

  The first insulating member 50 is disposed between a portion other than the center of the deformable plate 40 and the positive electrode current collector 10. The first insulating member 50 has a through hole at a portion corresponding to the center of the deformed plate where the deformed plate 40 and the positive electrode current collector 10 are connected. The first insulating member 50 and the second insulating member 150 are connected and fixed by engagement. The fixing method is not particularly limited. Here, the fixing is performed by latch fixing using the claw portions 55 formed on the first insulating member 50. This fixed portion is formed on the outer peripheral edge of the first insulating member 50.

  In the positive electrode current collector 10, a through hole is formed at the center. As shown in FIG. 5, two through holes on both sides are also formed on both sides of the through hole at the center of the positive electrode current collector 10, respectively. In addition, the first insulating member 50 is provided with a through-hole opposite to the through-hole provided in the center of the positive electrode current collector 10, and on both sides thereof, two sides provided in the positive electrode current collector 10 are provided. Projections are formed at positions corresponding to the through holes on the side.

  The protrusions of the first insulating member 50 are respectively inserted into the through holes on both sides of the positive electrode current collector 10, and the first insulating member 50 and the positive electrode current collector are heated by heating the tip of the protrusion to increase the diameter. The body 10 is fixed.

  A peripheral region 18 having a thickness smaller than other portions is provided around a central portion of the through hole at the center of the positive electrode current collector 10, and a peripheral region of the peripheral region 18 is surrounded by the through hole. Thus, the annular thin portion 15 is formed. The thin portion 15 is provided in a groove shape so that the thickness is smaller than that of the peripheral region 18. An inner peripheral rib portion 19 is provided on the inner peripheral edge of the peripheral region 18, and the deformable plate 40 is laser-welded at the inner peripheral rib portion 19 to electrically connect the deformable plate 40 and the positive electrode current collector 10. I have. Note that the inner peripheral rib 19 is not an essential component, and the inner peripheral rib 19 can be omitted.

  The operation of the current interruption mechanism 200 in the present embodiment is as follows. When the pressure in the battery case 100 increases and exceeds a predetermined value, the deformable plate 40 is deformed such that the central portion of the deformable plate 40 approaches the sealing plate 120. The positive electrode current collector 10 is welded to the deformable plate 40 at the inner peripheral rib portion 19. The thin portion 15 surrounds the welded portion between the positive electrode current collector 10 and the deformable plate 40. Therefore, the thin portion 15 is broken all around due to the above-described deformation of the deformable plate 40, so that the electrical connection between the deformable plate 40 and the positive electrode current collector 10 is cut off, and the current is cut off.

  Next, the shape of the thin portion 15 of the present embodiment will be described. As shown in FIGS. 7 and 8, in a cross section cut along the thickness direction of the positive electrode current collector 10, the thin portion 15 has a concave shape, and a bottom portion 81 which is a bottom of the concave portion and a bottom portion 81 of the bottom portion 81. It has a first side surface portion 82 connecting one end portion 91 and one outer edge of the thin portion 15, and a second side portion 83 connecting the other end portion 92 and the other outer edge of the thin portion 15. ing. The thickness a of the bottom portion 81 at one end 91 is smaller than the thickness b of the bottom portion 81 at the other end 92. That is, the bottom surface portion 81 of the thin portion 15 is not parallel to the surface 80 of the thin region 18 on the sealing plate 120 side but inclined.

  Although the thin portion 15 is recessed from the peripheral region 18 and has a reduced thickness, the outer edge of the thin portion 15 is a boundary portion where the thin portion 15 starts to be recessed.

  On the other hand, the conventional thin portion will be described with reference to an example shown in FIGS. 9 and 10 and another example shown in FIG. In the example of the conventional thin portion 115 shown in FIGS. 9 and 10, the bottom portion 84 is parallel to the surface 80 of the thin region 18 on the side of the sealing plate 120, and one end of the bottom portion 84 and the other end thereof. The thickness d of the bottom surface portion 84 at the end is the same for both. Further, in the example of the conventional thin portion 215 shown in FIG. 11, the cross-sectional shape is V-shaped and does not have a flat bottom portion.

  The inventor of the present application examined the easiness of breakage of the thin portion as follows.

  With respect to the thin portion 15 of the present embodiment and the conventional thin portions 115 and 215, the state of breakage when the deformable plate 40 is deformed was predicted using the finite element method. Aluminum alloy Al100-O was used as a material of the positive electrode current collector 10. When a simulation is performed in which a load is applied to the deformed plate 40 and the load is gradually increased to deform the deformed plate 40, the thin portion 15 of the present embodiment having the bottom portion and the thin portion 115 of the related art have a bottom surface. As a result, stress concentrates on the end 91 located on the side (the left side in FIG. 8) of the bottom surfaces 81 and 84 that is farther from the connection between the positive electrode current collector 10 and the deformable plate 40. When the deformation of the deformable plate 40 exceeded a certain threshold value, one end portion 91 was broken. On the other hand, in the V-shaped thin portion 215, stress was concentrated at the tip of the V-shaped portion, and the portion was broken.

  The thickness a of the bottom portion 81 at one end 91 of the thin portion 15 of this embodiment, the thickness d of the bottom portion 84 of the conventional thin portion 115, and the thickness of the V-shaped tip portion of the conventional thin portion 215 According to the simulation, the magnitude of the load causing the deformation leading to the fracture is in the order of the V-shaped thin portion 215> the flat bottom thin portion 115> the thin portion 15 of the present embodiment. Was. As described above, the thin portion 115 having a flat bottom surface is broken by a smaller load than the V-shaped thin portion 215. This is because the presence of a flat bottom surface in the thin portion 115 causes the thin portion 115 to be easily deformed so that the angle formed between the bottom surface and the side portion increases with the deformation of the deformable plate 40. On the other hand, in the V-shaped thin portion 215, since the thin portion 215 is unlikely to change so that the angle formed by the pair of side portions increases, the load required to break the V-shaped thin portion 215 increases. In addition, the thin portion 15 of the present embodiment breaks with a smaller load than the thin portion 115 having a flat bottom because the inclined bottom has a higher strain than the flat bottom. Is thought to be concentrated.

  As described above, since the thin portion 15 of the present embodiment breaks with a smaller load than the two conventional thin portions 115 and 215 even when the thickness is the same, the thin portion 15 is used in manufacturing the positive electrode current collector member. And / or even if an impact or a large force is applied during the assembly of the battery, the final breaking load does not change unless the thickness a of the bottom surface portion 81 of the one end portion 91 changes as a result. Variations in the breaking load for each battery can be avoided.

  In the thin portion 15 of the present embodiment, the distance c between one end 91 and the other end 92 (the distance along the surface of the bottom portion 81 on the electrode body 110 side, the width of the bottom portion 81) is It is preferable that the thickness be larger than the thickness a of the bottom surface portion 81 at one end portion 91. With such a relationship, when a large number of thin portions 15 are manufactured, the variation in the breaking load is reduced.

  A / b is preferably not less than 1/2 and not more than 9/10. If a / b is smaller than ２, the difference from the conventional V-shaped thin portion 215 becomes considerably small. If a / b is larger than 9/10, the difference from the conventional thin portion 115 having a flat bottom surface is considerably reduced.

  Furthermore, in the thin portion 15 of the present embodiment, the value of (ba) / c is preferably 0.17 or more and 0.58 or less. If it is smaller than 0.17, the difference from the conventional thin portion 115 having a flat bottom surface becomes considerably small. If it is larger than 0.58, the difference from the conventional V-shaped thin portion 215 will be small.

  When a thin portion is actually formed, the corner portion is rounded (the corner has an R). Even if there is a rounded portion in this way, except when the entire cross section of the thin portion is a circular arc or a part of an ellipse that is entirely curved and a corner cannot be recognized, that is, the corner If the part can be determined, it can be determined whether or not it corresponds to the thin part of the present embodiment.

(Embodiment 2)
The secondary battery according to the second embodiment is different from the secondary battery according to the first embodiment in the shape of the thin portion, but is otherwise the same as the first embodiment. Are described below.

  As shown in FIGS. 12 and 13, the thin portion 315 of this embodiment has first side portions 86 and 87 extending from one end to one outer edge of the thin portion 315 and are bent in the middle. Is different from the first embodiment. The second side surface portion 88 is the same as in the first embodiment. Of the bent first side surface portions, the bottom surface side surface portion 86 on the side closer to the bottom surface portion 85 has the same angle as the first side surface portion 82 of the first embodiment (the surface of the thin region 18 on the sealing plate 120 side). 80, about 60 degrees). The opening side surface portion 87 has an angle perpendicular to the surface 80 of the thin region 18 on the sealing plate 120 side.

  Thus, even if the first side surface of the thin portion 315 is bent, the bottom surface 85 is present, and the thickness of the bottom surface 85 is different between one end and the other end. If the larger end is located on the side closer to the weld between the positive electrode current collector 10 and the deformed plate (in FIG. 12, the side closer to the inner peripheral rib 19 that is the connection portion with the deformed plate), The effects described in the first mode are exerted. Further, it is preferable that c1> a1, a1 / b1 is preferably 以上 or more and 9/10 or less, and the value of (b1-a1) / c1 is 0.17 or more and 0.58 or less. Is preferred.

(Other embodiments)
The above-described embodiment is an exemplification of the present invention, and the present invention is not limited to these examples, and well-known technology, conventional technology, and known technology may be combined with these examples, or may be partially replaced. Modified inventions easily conceived by those skilled in the art are also included in the present invention.

  The secondary battery of the present invention is applicable to both non-aqueous electrolyte secondary batteries and alkaline secondary batteries such as nickel-hydrogen secondary batteries. The deformed plate has a predetermined effect if it is connected to one of the positive electrode current collector and the negative electrode current collector, but may be connected to both.

  The battery case is not limited to a rectangular parallelepiped shape (square), and may be a cylindrical shape with a bottom. Also, the cross section of the tubular member of the conductive member is not limited to a rectangle but may be a circle, an ellipse, or a polygon.

  The side portions may be vertical walls.

  Further, in the first embodiment, the example in which the external terminal and the conductive member are formed as separate components has been described. However, the external terminal and the conductive member may be formed as one component.

Reference Signs List 10 positive electrode current collector 15 thin portion 20 negative electrode current collector 30 conductive member 40 deformed plate 50 first insulating member 70 second insulating member 81, 85 bottom portions 82, 86, 87 first side portions 83, 88 second Side surface part 91 One end part 92 The other end part 100 Battery case 110 Electrode body 120 Sealing plate 130 Positive terminal (external terminal)
132 Negative electrode terminal (external terminal)
200 Current cut-off mechanism 315 Thin section

Claims (5)

A battery case having an opening;
An electrode body containing a positive electrode and a negative electrode housed in the battery case,
A current collector electrically connected to the positive or negative electrode,
A sealing plate for sealing the opening,
An external terminal attached to the sealing plate,
A conductive member located between the sealing plate and the electrode body, electrically connected to the external terminal, and having an opening on the electrode body side;
A deformable plate that seals the opening portion, is connected to the current collector, and deforms when the pressure in the battery case becomes a predetermined value or more,
The current collector has a concave portion, and a thin portion that is broken when the deformed plate is deformed is provided,
In a cross section cut along the thickness direction of the current collector, the thin portion is a bottom portion that is the bottom of the concave shape, and a second portion that connects one end of the bottom portion and one outer edge of the thin portion. A second side portion connecting the first side portion and the other end portion and the other outer edge of the thin portion,
The thickness a of the bottom portion at the one end is smaller than the thickness b of the bottom portion at the other end,
The secondary battery, wherein the other end is provided at a position closer to a connection portion with the deformable plate than the one end.   The secondary battery according to claim 1, wherein the thin portion has a groove shape surrounding a portion where the deformable plate and the current collector are connected.   3. The secondary battery according to claim 1, wherein a distance c between the one end and the other end is greater than a thickness a of the bottom surface at the one end. 4.   The thickness (a) of the bottom surface at the one end is not less than １ ／ and not more than 9/10 of the thickness (b) of the bottom at the other end. Rechargeable battery.   In the thickness a of the bottom surface at the one end, the thickness b of the bottom surface at the other end, and the distance c between the one end and the other end, (ba−c) / c The rechargeable battery according to claim 4, wherein the value is 0.17 or more and 0.58 or less.

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