Secondary battery

Abstract

To provide a secondary battery that is able to prevent an empty space from being left between an exterior film and a battery stack.SOLUTION: In a secondary battery, a battery stack is disposed in an exterior body. The battery stack has a battery portion in which a positive electrode portion, a separator impregnated with an electrolytic solution, and a negative electrode portion are stacked in that order. The exterior body includes a first exterior film and a second exterior film. The first exterior film covers one side of the battery stack in a stacking direction of the battery portion, and the second exterior film covers the other side of the battery stack in the stacking direction of the battery portion. A first pressing plate that presses the battery stack in a planar manner toward the second exterior film is provided between the first exterior film and the battery stack. The first pressing plate is located at a position overlapping the battery portion in a plan view and bites into the first exterior film in the stacking direction of the battery portion.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a secondary battery. [Background technology]

[0002] BACKGROUND ART Conventionally, laminate-type secondary batteries have been known in which a laminated body in which positive electrodes, negative electrodes, and separators are alternately stacked is sealed with two laminate films (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2018 / 198612 Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, in laminated secondary batteries, when a thick nonwoven fabric is used as a separator or when the total thickness of the laminate is large, such as when the number of laminate layers is large, sealing with two laminate films can cause problems such as the laminate being too thick to sufficiently reduce the pressure using a laminator, the shrinkage force of the laminate films varying depending on the position on the laminate, or the laminate films not being able to adhere sufficiently to each other.

[0005] Therefore, the inventors prototyped a secondary battery in which one of the two laminate films used to seal the laminate was pre-formed to form a recess, and the laminate was placed in the recess, and the laminate was then sealed with the two laminate films using a laminator.

[0006] In this prototype secondary battery, the thickness of the stack was absorbed by the recesses in the laminate film, so the stack could be sealed with the laminate film even when the separator was thick or the number of layers was large. However, in the structure of this prototype secondary battery, since the recess is formed in advance, if the depth of the recess is deeper than the thickness of the laminate, the difference between the depth of the recess and the thickness of the laminate may not be absorbed by the shrinkage of the laminate film.In such cases, a gap is formed between the laminate film and the laminate, resulting in a problem of reduced battery capacity.

[0007] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a secondary battery that can prevent the formation of voids between the exterior film and the battery stack. [Means for solving the problem]

[0008] One aspect of the present invention for solving the above-described problems is a secondary battery in which a battery stack is disposed within an exterior body, the battery stack having a battery unit in which a positive electrode unit, a separator impregnated with an electrolyte solution, and a negative electrode unit are stacked in this order, the exterior body having a first exterior film and a second exterior film, the first exterior film covering one side of the battery stack in the stacking direction of the battery units, and the second exterior film covering the other side of the battery stack in the stacking direction of the battery units, and a first pressure plate between the first exterior film and the battery stack that presses the battery stack into a plane toward the second exterior film, the first pressure plate being located at a position that overlaps with the battery unit in a planar view and that bites into the first exterior film in the stacking direction of the battery units.

[0009] According to this aspect, the first pressure plate presses the battery stack in a planar manner, so that the battery stack is compressed evenly by the pressing force of the first pressure plate, preventing the formation of voids between the first exterior film and the battery stack. According to this aspect, the first pressure plate is embedded in the first exterior film at the position where it overlaps with the battery section, so that the first exterior film deforms along the first pressure plate, and the unevenness caused by the shape of the battery section of the battery stack is less likely to be reflected in the first exterior film, resulting in a high level of design.

[0010] In a preferred aspect, the first exterior film has a recess, and the first pressure plate is located within the recess and bites into the bottom of the recess.

[0011] In a preferred aspect, a second pressure plate is provided between the second exterior film and the battery stack, which presses the battery stack in a planar manner toward the first exterior film, and the first pressure plate and the second pressure plate sandwich the battery stack.

[0012] In a preferred aspect, the second pressure plate is located at a position overlapping the battery portion in a plan view and is embedded in the second exterior film.

[0013] In a preferred aspect, the first pressure plate has insulating properties.

[0014] In a preferred aspect, the first pressing plate has greater rigidity than the separator.

[0015] In a preferred aspect, the first pressing plate has an average thickness greater than that of the separator.

[0016] In a preferred aspect, the separator is made of a nonwoven fabric and is compressed by the pressure from the first pressure plate.

[0017] In a preferred aspect, the exterior body has an internal space in which the battery stack and the first pressure plate are disposed, and the pressure in the internal space is 2000 Pa or less.

[0018] In a preferred aspect, the battery stack has an average thickness of 3 mm or more.

[0019] In a preferred aspect, the battery has an electrode extraction member, the electrode extraction member extends inside and outside the exterior body, and is connected to the positive electrode portion or the negative electrode portion inside the exterior body via a connection portion, and the first pressing plate overlaps the connection portion when viewed from above.

[0020] The above aspects may be made dependent on each other, or some of the configurations may be quoted or substituted for each other, as long as they are included in the technical scope of the present invention. [Effects of the Invention]

[0021] The secondary battery of the present invention can prevent the formation of voids between the exterior film and the battery stack. [Brief explanation of the drawings]

[0022] [Figure 1] 1A and 1B are explanatory diagrams conceptually illustrating a secondary battery according to a first embodiment of the present invention, in which (a) is a perspective view of the secondary battery, and (b) is a cross-sectional view of (a). DETAILED DESCRIPTION OF THE INVENTION

[0023] Hereinafter, an embodiment of the present invention will be described in detail. The positional relationship of each component is based on the orientation shown in Fig. 1 unless otherwise specified. That is, the reference orientation of the secondary battery 1 is one in which the first exterior film 50 forms the upper surface and the second exterior film 51 forms the lower surface.

[0024] The secondary battery 1 of the first embodiment of the present invention is a lithium-ion secondary battery, and as shown in FIG. 1, includes a battery stack 2, electrode extraction members 3a and 3b, an electrolytic medium 4, an outer casing 5, and pressure plates 6 and 7, and the battery stack 2, the electrolytic medium 4, and the pressure plates 6 and 7 are housed and sealed within the outer casing 5.

[0025] <Battery stack 2> As shown in FIG. 1(b), the battery stack 2 has a plurality of positive electrode parts 20, a plurality of negative electrode parts 21, and a plurality of separators 22, and is provided with a battery part 25 in which the positive electrode parts 20, the separators 22, and the negative electrode parts 21 are stacked in this order. In the battery stack 2 of this embodiment, the electrode parts 20, 21 and the separators 22 are arranged alternately, as in ... / separator 22 / positive electrode part 20 / separator 22 / negative electrode part 21 / separator 22 / ..., with the separators 22 being arranged on the outermost sides in the stacking direction.

[0026] The average thickness of the battery stack 2 is preferably 3 mm or more and 30 mm or less.

[0027] (positive electrode part 20) The positive electrode part 20 is an intercalation electrode in which a positive electrode active material layer 31 is laminated on at least one main surface of a positive electrode current collector 30, and is capable of inserting and extracting Li ions. In the positive electrode part 20 of this embodiment, positive electrode active material layers 31 are laminated on both main surfaces of a positive electrode current collector 30, as shown in FIG. 1(b). As shown in FIG. 1(b), in one direction in the longitudinal direction X, the positive electrode current collectors 30, 30 protrude outward from the separator 22 with respect to the battery section 25 as a reference, forming protruding portions 70a, 70b in the positive electrode sections 20a, 20b, and the protruding portions 70a, 70b are stacked on the outside of the separator 22 to form a stacked portion 71.

[0028] (negative electrode part 21) The negative electrode section 21 is an intercalation electrode in which a negative electrode active material layer 41 is laminated on at least one main surface of a negative electrode current collector 40, and is capable of inserting and extracting Li ions. In the negative electrode section 21 of this embodiment, negative electrode active material layers 41 are laminated on both main surfaces of a negative electrode current collector 40, as shown in FIG. 1(b). As shown in FIG. 1(b), in the negative electrode portions 21a, 21b, the negative electrode current collectors 40, 40 protrude outward from the separator 22 in the direction opposite to the protruding direction of the positive electrode current collectors 30, 30 of the positive electrode portions 20a, 20b in the longitudinal direction X, with the battery portion 25 as the reference, to form protruding portions 80a, 80b, and the protruding portions 80a, 80b are stacked on the outside of the separator 22 to form a stacked portion 81.

[0029] (Current collectors 30, 40) The current collectors 30 and 40 are electrically conductive plate-like or film-like bodies. The current collectors 30 and 40 are not particularly limited as long as they are electrically conductive, and for example, metals such as aluminum and alloys thereof can be used. The average thickness of the current collectors 30 and 40 is preferably 5 μm or more and 30 μm or less.

[0030] (Cathode active material layer 31) The positive electrode active material layer 31 is an active material layer including a positive electrode active material, a conductive additive, and a binder. The average thickness of the positive electrode active material layer 31 is preferably 10 μm or more and 200 μm or less.

[0031] (Negative electrode active material layer 41) The negative electrode active material layer 41 is an active material layer including a negative electrode active material, a conductive additive, and a binder. The average thickness of the negative electrode active material layer 41 is preferably 10 μm or more and 200 μm or less.

[0032] (Separator 22) The separator 22 has insulating properties and is capable of containing the electrolytic medium 4 . The separator 22 is not particularly limited, and examples thereof include nylon, cellulose, polysulfone, polyethylene, polypropylene, polybutene, polyacrylonitrile, polyimide, polyamide, polyethylene terephthalate, and woven fabrics, nonwoven fabrics, and microporous membranes made of a combination of two or more of these. The separator 22 of this embodiment is made of nonwoven fabric and has elasticity and stretchability. Before the secondary battery 1 is assembled, the separator 22 preferably has an average thickness of 20 μm or more and 100 μm or less. The porosity of the separator 22 before the secondary battery 1 is assembled is preferably 50% or more and 90% or less.

[0033] <Electrode extraction members 3a, 3b> As shown in FIG. 1(b), the positive electrode lead-out member 3a is electrically connected to at least one of the positive electrode sections 20 constituting the battery stack 2 within the exterior case 5, and is a positive electrode terminal that extends inside and outside the exterior case 5. The negative electrode lead-out member 3b is electrically connected to at least one of the negative electrode sections 21 that make up the battery stack 2 within the exterior case 5, and is a negative electrode terminal that extends inside and outside the exterior case 5. The electrode extraction members 3a and 3b are conductive plate-like bodies. The electrode extraction members 3a and 3b are not particularly limited as long as they are conductive, and for example, metals such as aluminum and alloys thereof can be used.

[0034] <Electrolytic medium 4> The electrolytic medium 4 is not particularly limited as long as it has lithium ion conductivity, but may be a non-aqueous electrolyte solution in which a solute is dissolved in a non-aqueous solvent, a gel electrolyte in which a polymer is impregnated with a non-aqueous electrolyte solution in which a solute is dissolved in a non-aqueous solvent, etc. The electrolytic medium 4 may be in a solid state or may be a solid electrolyte. The electrolytic medium 4 of this embodiment uses a non-aqueous electrolyte, a part of which is impregnated into the separator 22 .

[0035] <Exterior body 5> As shown in FIG. 1(b), the exterior body 5 has an internal space 52 and is a sealing member that houses and seals the battery stack 2, the electrolytic medium 4, and the pressure plates 6 and 7 in the internal space 52, and is chemically stable against the electrolytic medium 4 and has water vapor barrier properties. As shown in FIG. 1, the exterior body 5 is made up of a first exterior film 50 and a second exterior film 51. The exterior films 50 and 51 are made of a laminate film containing a laminate resin.

[0036] The first exterior film 50 is a film that covers the upper side of the battery stack 2, and has a recess 53 formed in advance to accommodate part or all of the battery stack 2. The recess 53 is a depression that has a depth that increases upward. The depth of the recess 53 before the secondary batteries 1 are assembled is preferably smaller than the thickness of the battery stack 2 before the secondary batteries 1 are assembled, and is preferably between 3 mm and 30 mm. The depth of the recess 53 before the secondary battery 1 is assembled is preferably 50% to 100% of the thickness of the battery stack 2 alone before the secondary battery 1 is assembled, and more preferably 70% to 100%. The depth of the recess 53 before the secondary batteries 1 are assembled is preferably smaller than the total thickness of the battery stack 2 and the pressure plates 6, 7 before the secondary batteries 1 are assembled.

[0037] The second exterior film 51 is a film that covers the lower side of the battery stack 2, and, unlike the first exterior film 50, is a flat film that does not have recesses 53 formed therein before the secondary battery 1 is assembled.

[0038] <Pressure plates 6, 7> The pressure plates 6, 7 are plate-like bodies that are thicker on average than the separators 22 and have high rigidity, and press the battery stack 2 in the stacking direction of the battery sections 25. The first pressing plate 6 is a gap closing member that fills the gap between the battery stack 2 and the first exterior film 50, and the second pressing plate 7 is a gap closing member that fills the gap between the battery stack 2 and the second exterior film 51. The pressure plates 6 and 7 are insulating plates having insulating properties, and for example, insulating resin plates such as polypropylene can be used. As shown in FIG. 1, when viewed from the battery section 25 side, at least the outer surfaces of the pressure plates 6 and 7 are smooth, and it is preferable that both the outer and inner main surfaces are smooth. The pressure plates 6 and 7 preferably have an average thickness of 0.5 mm or more and 2 mm or less.

[0039] Next, the positional relationship between the various parts of the secondary battery 1 of this embodiment will be described.

[0040] As shown in Figure 1, in the stacking direction of the battery section 25 of the battery stack 2, the secondary battery 1 has a first pressure plate 6 covering one outer side (upper side) of the battery stack 2, and a first exterior film 50 covering the further outer side (upper side) of the first pressure plate 6. When viewed in a plan view, the first pressure plate 6 overlaps at least most of the battery section 25 of the battery stack 2, preferably overlaps the entire battery section 25 of the battery stack 2, more preferably overlaps the parts of the battery stack 2 other than the stack sections 71 and 81, and even more preferably overlaps the entire battery stack 2. In this context, "majority" means more than 50% of the total.

[0041] In the stacking direction of the battery section 25 of the battery stack 2, the secondary battery 1 has a second pressure plate 7 covering the other outer side (lower side) of the battery stack 2, and a second exterior film 51 covering the further outer side (lower side) of the second pressure plate 7. When viewed in a plan view, the second pressure plate 7 overlaps at least most of the battery section 25 of the battery stack 2, preferably overlaps the entire battery section 25 of the battery stack 2, more preferably overlaps the parts of the battery stack 2 other than the stack sections 71 and 81, and even more preferably overlaps the entire battery stack 2.

[0042] As shown in FIG. 1, the positive electrode lead-out member 3a is connected to the stacked portion 71 of the battery stack 2 inside the exterior package 5, and extends to the outside of the exterior package 5 between the exterior films 50, 51. The negative electrode extraction member 3b is connected to the stack portion 81 of the battery stack 2 inside the exterior body 5, and extends to the outside of the exterior body 5 between the exterior films 50, 51. In other words, the negative electrode extraction member 3b extends in the opposite direction to the positive electrode extraction member 3a. The electrode extraction members 3a, 3b have their connection portions with the stacked portions 71, 81 of the battery stack 2 located between the first pressure plate 6 and the second pressure plate 7, and are protected by the first pressure plate 6 and the second pressure plate 7.

[0043] When viewed from above, the secondary battery 1 has exterior films 50, 51 bonded to surround the battery section 25 of the battery stack 2, and the internal space 52 of the exterior body 5 is sealed in a decompressed state. The pressure in the internal space 52 of the exterior body 5 is equal to or lower than atmospheric pressure, and is preferably equal to or higher than 1 Pa and equal to or lower than 2000 Pa.

[0044] With the battery section 25 as the reference point, the first pressure plate 6 presses the battery stack 2 inward (downward) in a planar manner, and the second pressure plate 7 presses the battery stack 2 inward (upward) in a planar manner. That is, in the battery stack 2, the battery section 25 is sandwiched between the first pressure plate 6 and the second pressure plate 7, and the separator 22 located between the first pressure plate 6 and the second pressure plate 7 is compressed by the pressure of the first pressure plate 6 and / or the second pressure plate 7.

[0045] As shown in FIG. 1, the exterior films 50 and 51 are shrunk along the pressure plates 6 and 7 in the internal space 52, and recesses 90 and 91 in which the pressure plates 6 and 7 are disposed are formed at the bottom. When viewed from the battery section 25 side, the first pressing plate 6 is embedded in the inner surface (lower surface) of the first exterior film 50, and the first pressing plate 6 is reflected on the outer surface (upper surface). Specifically, the first pressing plate 6 is embedded in the first exterior film 50 at the bottom of the recess 90. The second pressing plate 7 is inserted into the inner surface (upper surface) of the second exterior film 51, and the second pressing plate 7 is reflected on the outer surface (lower surface). Specifically, the second pressing plate 7 is inserted into the second exterior film 51 at the bottom of the recess 91. The recess 90 is a preformed recess 53 that has been deformed by lamination, and is deeper than the recess 91.

[0046] According to the secondary battery 1 of this embodiment, a first pressing plate 6 that presses the battery stack 2 in a planar manner toward the second exterior film 51 side is provided between the battery stack 2 and a first exterior film 50 that covers one side of the battery stack 2, and the first pressing plate 6 is positioned so as to overlap the battery section 25 when viewed in a plan view, and is embedded in the first exterior film 50 in the stacking direction. That is, in the secondary battery 1 of this embodiment, the first pressure plate 6 presses the battery stack 2 in a planar manner, so that the battery stack 2 is compressed evenly by the pressing force of the first pressure plate 6, preventing the formation of a gap between the first exterior film 50 and the battery stack 2. Furthermore, in the secondary battery 1 of this embodiment, the first pressure plate 6 is embedded in the first exterior film 50 at a position where it overlaps with the battery section 25, so that the first exterior film 50 deforms along the first pressure plate 6, and the unevenness due to the shape of the battery section 25 of the battery stack 2 is less likely to be reflected in the first exterior film 50, resulting in a high level of design.

[0047] According to the secondary battery 1 of this embodiment, the first pressing plate 6 is located within the recess 90 of the first exterior film 50 and bites into the bottom of the recess 90. Therefore, the shape of the first pressing plate 6 is likely to be reflected on the outer surface (upper surface) of the first exterior film 50 when viewed from the battery section 25 side.

[0048] The secondary battery 1 of this embodiment has a second pressure plate 7 between the second exterior film 51 and the battery stack 2 that presses the battery stack 2 flatly toward the first exterior film 50, and the first pressure plate 6 and the second pressure plate 7 sandwich the battery stack 2. This allows the thickness of the battery section 25 of the battery stack 2 to be compressed, reducing the overall thickness.

[0049] In the secondary battery 1 of this embodiment, the second pressing plate 7 is positioned so as to overlap the battery section 25 in a plan view, and is embedded in the second exterior film 51. This allows the second exterior film 51 to deform along the second pressing plate 7, making it difficult for the second exterior film 51 to reflect the irregularities caused by the shape of the battery section 25 of the battery stack 2, resulting in a high level of design.

[0050] According to the secondary battery 1 of this embodiment, the first pressing plate 6 has insulating properties, and therefore can prevent electricity from flowing to the first exterior film 50 side.

[0051] According to the secondary battery 1 of this embodiment, the first pressing plate 6 has greater rigidity than the separator 22, and is therefore less likely to be deformed by the reaction force from the separator 22.

[0052] In the secondary battery 1 of this embodiment, the separator 22 is made of nonwoven fabric and is compressed by the pressure from the first pressing plate 6. This allows the thickness of the separator 22 to be reduced, preventing contact between the positive electrode part 20 and the negative electrode part 21 and reducing the thickness of the battery stack 2.

[0053] In the secondary battery 1 of this embodiment, the battery stack 2 and pressure plates 6 and 7 are arranged in the internal space 52 of the exterior housing 5, and the pressure in the internal space 52 is 2000 Pa or less. Therefore, the battery stack 2 can be pressed by the pressure plates 6 and 7 due to the pressure difference between the internal space 52 and the external pressure (atmospheric pressure).

[0054] In the secondary battery 1 of this embodiment, the pressure plates 6 and 7 each have a smooth surface facing the battery component 25 of the battery stack 2, allowing them to press the battery component 25 of the battery stack 2 evenly.

[0055] According to the secondary battery 1 of this embodiment, when viewed in a plane, the pressure plates 6, 7 overlap the connection portions between the electrode extraction members 3a, 3b and the stacked portions 71, 81 of the battery stack 2, thereby protecting the connection portions and preventing breakage, etc.

[0056] In the above-described embodiment, the secondary battery 1 has two positive electrode parts 20 as shown in FIG. 1 , but the present invention is not limited to this, and the secondary battery 1 may have one positive electrode part 20, or may have three or more positive electrode parts 20. Similarly, in the above-described embodiment, the secondary battery 1 has two negative electrode parts 21, but the present invention is not limited to this, and the secondary battery 1 may have one negative electrode part 21, or may have three or more negative electrode parts 21. Similarly, in the above-described embodiment, the secondary battery 1 has five separators 22, but the present invention is not limited to this, and the secondary battery 1 may have one separator 22, or may have three or more separators 22.

[0057] In the above embodiment, the separators 22 are positioned on the outermost side of the battery stack 2 in the stacking direction of the battery modules 25, but the present invention is not limited to this. The electrode modules 20, 21 may also be positioned on the outermost side of the battery stack 2. In this case, the pressure plates 6, 7 press against the electrode modules 20, 21.

[0058] In the above embodiment, the secondary battery 1 has two pressure plates 6 and 7, but the present invention is not limited to this. The secondary battery 1 may have only one of the pressure plates 6 and 7.

[0059] In the above embodiment, the pressure plates 6, 7 overlap the entire battery stack 2 in plan view, but the present invention is not limited to this. The pressure plates 6, 7 only need to overlap at least the battery section 25 of the battery stack 2 in plan view.

[0060] In the above-described embodiment, the positive electrode extraction member 3a and the negative electrode extraction member 3b protrude from the exterior body 5 in opposite directions in the length direction X, but the present invention is not limited to this. The positive electrode extraction member 3a and the negative electrode extraction member 3b may protrude from the exterior body 5 in the same direction in the length direction X. In this case, the positive electrode extraction member 3a and the negative electrode extraction member 3b are preferably arranged parallel to each other in the width direction (the direction perpendicular to the length direction X).

[0061] In the above embodiment, the second exterior film 51 does not have the recess 53 formed therein before assembling the secondary battery 1, but the present invention is not limited to this. Similar to the first exterior film 50, the second exterior film 51 may have the recess 53 formed therein for accommodating part or all of the battery stack 2 before assembling the secondary battery 1. In this case, the recess 53 of the first exterior film 50 may be omitted.

[0062] In the above embodiment, the secondary battery 1 is a lithium ion secondary battery, but the present invention is not limited to this and may be any other secondary battery.

[0063] In the above-described embodiments, each component can be freely substituted or added between the respective embodiments as long as it falls within the technical scope of the present invention. [Explanation of symbols]

[0064] 1 Secondary battery 2 Battery stack 5. Exterior body 6. First pressure plate 7 Second pressure plate 20,20a,20b Positive electrode part 21,21a,21b Negative electrode part 22 Separator 25 Battery section 50 First exterior film 51 Second outer film 52 Interior Space 53 Recess

Claims

1. A secondary battery having a battery stack disposed inside an exterior body, the battery stack has a battery section in which a positive electrode section, a separator impregnated with an electrolytic solution, and a negative electrode section are stacked in this order; The exterior body has a first exterior film and a second exterior film, the first exterior film covers one side of the battery stack in the stacking direction of the battery module, the second exterior film covers the other side of the battery stack in the stacking direction of the battery module, a first pressing plate is disposed between the first exterior film and the battery stack, and the first pressing plate presses the battery stack in a planar manner toward the second exterior film; The secondary battery, wherein the first pressing plate is positioned so as to overlap the battery portion in a plan view and is embedded in the first exterior film in the stacking direction of the battery portion.

2. the first exterior film has a recess, The secondary battery according to claim 1 , wherein the first pressure plate is located within the recess and bites into the bottom of the recess.

3. a second pressing plate is disposed between the second exterior film and the battery stack, and presses the battery stack in a planar manner toward the first exterior film; The secondary battery according to claim 1 , wherein the first pressure plate and the second pressure plate sandwich the battery stack.

4. The secondary battery according to claim 3 , wherein the second pressing plate is positioned so as to overlap the battery portion in a plan view and is embedded in the second exterior film.

5. The secondary battery according to claim 1 , wherein the first pressure plate has insulating properties.

6. The secondary battery according to claim 1 , wherein the first pressing plate has a greater rigidity than the separator.

7. The secondary battery according to claim 1 , wherein the first pressing plate has an average thickness greater than that of the separator.

8. 3. The secondary battery according to claim 1, wherein the separator is made of a nonwoven fabric and is compressed by the pressure from the first pressure plate.

9. The exterior body has an internal space, the battery stack and the first pressing plate are disposed in the internal space, 3. The secondary battery according to claim 1, wherein the pressure in the internal space is 2000 Pa or less.

10. The secondary battery according to claim 1 or 2, wherein the battery stack has an average thickness of 3 mm or more.

11. An electrode extraction member is provided, the electrode extraction member extends from the inside to the outside of the exterior body and is connected to the positive electrode portion or the negative electrode portion inside the exterior body via a connection portion, The secondary battery according to claim 1 , wherein the first pressing plate overlaps the connecting portion in a plan view.

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