Secondary battery

Abstract

To suppress deterioration of battery characteristics.SOLUTION: The laminated electrode body 20 and the electrolytic solution 15 are accommodated in the case body 12. A positive electrode plate 22 and a negative electrode plate 24 are laminated, and a separator 26 is sandwiched between the positive electrode plate 22 and the negative electrode plate 24 and folded. The positive electrode plates 22 and the negative electrode plates 24 are opposed to the opposed side face parts 12b inside the cylindrical case body 12, and the positive electrode plates 22 and the negative electrode plates 24 are alternately arranged. A first end portion 26e1 and a second end portion 26e2 are formed at a lower portion of the laminated electrode body 20. The position of the upper edge 26 e U of the second end portion 26e2 is disposed below the liquid surface 15a of the electrolytic solution 15.SELECTED DRAWING: Figure 7

Description

[Technical Field]

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

[0002] International Publication No. 2019 / 064740 discloses a stacked secondary battery that suppresses adverse effects such as electrode deformation caused by folds in the separator. In this secondary battery, the separator is folded back at the end of the electrode. In the secondary battery disclosed in this publication, the folds in the separator and the end of the negative electrode are separated by a predetermined distance. This prevents adverse effects caused by the folds in the separator. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2019 / 064740 Summary of the Invention [Problem to be solved by the invention]

[0004] The inventors of the present invention would like to suppress the deterioration of battery characteristics. [Means for solving the problem]

[0005] The secondary battery disclosed herein includes an electrode assembly including a plurality of first electrode plates, a plurality of second electrode plates having a polarity different from that of the first electrode plates, and a separator; an electrolyte; a cylindrical case body that accommodates the electrode assembly and the electrolyte; a first sealing plate attached to an opening on a first side of the case body; and a second sealing plate attached to an opening on a second side of the case body. the case body has a pair of opposing side surfaces, the plurality of first electrode plates and the plurality of second electrode plates face the pair of opposing side surfaces inside the case body, and the first electrode plates and the second electrode plates are arranged alternately, the separator is strip-shaped, and is folded back in order to pass between the first electrode plates and the second electrode plates in order, thereby being arranged between the first electrode plates and the second electrode plates, and a first end of the separator is in contact with the plurality of first electrode plates and the plurality of second electrode plates. and the plurality of second electrode plates are arranged on the outer periphery of the electrode body in which the plurality of first electrode plates ... first electrode plates and the plurality of second electrode plates are arranged on the outer periphery of the electrode body in which the plurality of second electrode plates are arranged on the outer periphery of the electrode body in which the plurality of second electrode plates are arranged on the outer periphery of the electrode body in which the plurality of second electrode plates are arranged on the outer periphery of the electrode body in

[0006] Such a secondary battery can suppress deterioration of battery characteristics. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a perspective view of an electricity storage device 100 according to the first embodiment. [Figure 2] FIG. 2 is a schematic vertical cross-sectional view taken along the line AA in FIG. [Figure 3] FIG. 3 is a cross-sectional view of the laminated electrode body 20. As shown in FIG. [Figure 4] FIG. 4 is a schematic diagram showing the positive electrode plate 22 and the negative electrode plate 24. As shown in FIG. [Figure 5] FIG. 5 is a schematic diagram showing the inside of the case main body 12. As shown in FIG. [Figure 6] FIG. 6 is a rear view of the laminated electrode body 20. As shown in FIG. [Figure 7] FIG. 7 is a schematic diagram showing the inside of the case body 12 when the electricity storage device 100 is being charged. [Figure 8]FIG. 8 is a schematic diagram showing the inside of the case body 12 when the electricity storage device 100 is being discharged. [Figure 9] FIG. 9 is a schematic diagram showing the inside of an electricity storage device 100A according to the second embodiment. [Figure 10] FIG. 10 is a schematic diagram showing the inside of an electricity storage device 100B according to the third embodiment. [Figure 11] FIG. 11 is a schematic diagram showing the inside of an electricity storage device 100C according to the fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] Preferred embodiments of the technology disclosed herein will be described below with reference to the drawings as appropriate. Matters other than those specifically mentioned in this specification that are necessary for implementing the technology disclosed herein (for example, the general configuration and manufacturing process of an electricity storage device that does not characterize the technology disclosed herein) can be understood as design matters for those skilled in the art based on prior art in the relevant field. The technology disclosed herein can be implemented based on the content disclosed in this specification and common technical knowledge in the relevant field. Furthermore, in the following drawings, components and parts that perform the same function are designated by the same reference numerals, and duplicate explanations may be omitted or simplified.

[0009] First Embodiment <Electricity storage device 100> FIG. 1 is a perspective view of an electricity storage device 100 according to a first embodiment. FIG. 2 is a schematic longitudinal cross-sectional view taken along line AA in FIG. 1, illustrating the internal structure of the electricity storage device 100. As shown in FIG. 1, the electricity storage device 100 has a polygonal shape (more specifically, a rectangular parallelepiped shape) formed of hexahedrons. The electricity storage device 100 is installed as shown in FIG. 1 when actually used. In the following description, the symbols F, Rr, L, R, U, and D in the drawings represent front, rear, left, right, top, and bottom, and the symbols X, Y, and Z in the drawings represent the width direction of the electricity storage device 100, the thickness direction perpendicular to the width direction, and the up-down direction perpendicular to the width and thickness directions, respectively.

[0010] As shown in FIG. 1 or 2, the electricity storage device 100 includes a case 10, a stacked electrode assembly 20, a positive electrode terminal 30, a negative electrode terminal 40, and an electrolyte solution 15. Here, the electricity storage device 100 is a non-aqueous electrolyte secondary battery, such as a lithium-ion secondary battery. The electricity storage device 100 is configured by accommodating the stacked electrode assembly 20 and the electrolyte solution 15 in a case 10 to which the positive electrode terminal 30 and the negative electrode terminal 40 are attached. In this specification, the term "electricity storage device" refers to a general device that can be repeatedly charged and discharged, and is a concept that encompasses secondary batteries such as lithium-ion secondary batteries and nickel-metal hydride batteries, and capacitors such as lithium-ion capacitors and electric double layer capacitors.

[0011] Case 10 As shown in FIG. 2, the case 10 is a housing that houses the stacked electrode assembly 20 and the electrolyte solution 15. Here, the outer shape of the case 10 is a flat, bottomed rectangular parallelepiped (rectangular). The material of the case 10 is not particularly limited. The case 10 can be made of a metal such as aluminum or an aluminum alloy. The case 10 includes a case main body 12, a first sealing plate 14, and a second sealing plate 16.

[0012] <Case body 12> The case body 12 is a cylindrical member that houses the stacked electrode body 20 and the electrolyte solution 15. In this embodiment, the case body 12 is a cylindrical member that is open at both ends. The case body 12 can be formed, for example, by bending a single metal plate into a rectangular tube shape and joining the seams (for example, by welding). The case body 12 may also be formed by joining multiple metal plates together.

[0013] As shown in FIG. 2, the case body 12 has a pair of narrow faces 12a and a pair of wide faces 12b. The narrow faces 12a are substantially rectangular. The pair of narrow faces 12a face each other in the Z direction and form the upper and lower faces of the case body 12. The narrow faces 12a extend in the X and Y directions. In this embodiment, the narrow face 12a on one side in the Z direction (here, the lower side) is also referred to as a bottom face portion 12aa. The narrow face 12a on the other side in the Z direction (here, the upper side) is also referred to as a top face portion 12ab. The dimensions of the bottom face portion 12aa and the top face portion 12ab along the width direction X are longer than the dimensions along the thickness direction Y.

[0014] The pair of wide surfaces 12b are an example of a pair of opposing side surfaces in the present invention. In the following description, the "wide surfaces 12b" will also be referred to as "side surface portions 12b." The pair of wide surfaces 12b are substantially rectangular. The pair of wide surfaces 12b are disposed between the pair of narrow surfaces 12a and are continuous with the pair of narrow surfaces 12a. Here, the long sides of the pair of wide surfaces 12b are connected to the long sides of the pair of narrow surfaces 12a. The pair of wide surfaces 12b face each other in the X direction and form the front and rear surfaces of the case body 12. The wide surfaces 12b extend in the Y and Z directions. The front side of the side surface portions 12b will also be referred to as side surface portion 12ba. The rear side of the side surface portions 12b will also be referred to as side surface portion 12bb.

[0015] As shown in FIG. 2, openings 12h1 and 12h2 are formed at both ends (ends 12e1 and 12e2) of the case body 12 in the width direction X. The openings 12h1 and 12h2 are formed by the short sides of the bottom surface portion 12aa, the side surfaces 12ba and 12bb, and the top surface portion 12ab. The opening 12h1 is formed at the end 12e1 on the first side (right side) of the case body 12. The opening 12h2 is formed at the end 12e2 on the second side (left side) of the case body 12. The openings 12h1 and 12h2 are substantially rectangular. The stacked electrode body 20 is inserted through the openings 12h1 and 12h2.

[0016] <First sealing plate 14, second sealing plate 16> The first sealing plate 14 is a member attached to the opening 12h1 on the first side of the case body 12. The second sealing plate 16 is a member attached to the opening 12h2 on the second side of the case body 12. The first sealing plate 14 and the second sealing plate 16 are joined to the peripheral edges of the openings 12h1 and 12h2 of the case body 12. The first sealing plate 14 and the second sealing plate 16 are substantially rectangular plate-shaped members. The first sealing plate 14 and the second sealing plate 16 are joined to the peripheral edges of the openings 12h1 and 12h2 after the stacked electrode body 20 is housed in the case body 12. The first sealing plate 14 and the second sealing plate 16 joined to the case body 12 face each other in the width direction X. A positive electrode terminal 30 is provided on the first sealing plate 14. A negative electrode terminal 40 is provided on the second sealing plate 16. The distance between the first sealing plate 14 and the second sealing plate 16 in the width direction X is longer than the length of the laminated electrode body 20 in the width direction X. Thus, a gap GP is formed between the first sealing plate 14 and the second sealing plate 16 and the laminated electrode body 20. The first sealing plate 14 and the second sealing plate 16 may be provided with an inlet (not shown) for injecting the electrolyte 15 and a safety valve (not shown) that ruptures when the pressure inside the case 10 exceeds a predetermined value. The inlet and the safety valve are provided, for example, in either the first sealing plate 14 or the second sealing plate 16.

[0017] The positive electrode terminal 30 is provided on the first sealing plate 14. The positive electrode terminal 30 is an example of the first terminal of the present invention. The positive electrode terminal 30 is preferably made of metal, and more preferably made of, for example, aluminum or an aluminum alloy. The positive electrode terminal 30 is electrically connected to a positive electrode plate 22 (see also FIG. 3 ), which will be described later, inside the case 10 via a positive electrode current collector 32. The positive electrode terminal 30 may be attached via, for example, an insulator (not shown) or a gasket (not shown).

[0018] The negative electrode terminal 40 is provided on the second sealing plate 16. The negative electrode terminal 40 is an example of the second terminal of the present invention. The negative electrode terminal 40 is preferably made of metal, and more preferably made of, for example, copper or a copper alloy. The negative electrode terminal 40 is electrically connected to a negative electrode plate 24 (see also FIG. 3 ), which will be described later, inside the case 10 via a negative electrode current collector 42. The negative electrode terminal 40 may be attached via, for example, an insulator (not shown) or a gasket (not shown).

[0019] The electrolyte solution 15 is accommodated inside the case 10 together with the laminated electrode assembly 20. A portion of the electrolyte solution 15 is impregnated into the laminated electrode assembly 20. The electrolyte solution 15 is, for example, a non-aqueous electrolyte solution containing a non-aqueous solvent (organic solvent) and a supporting salt (electrolyte salt, such as a lithium salt or a sodium salt). Examples of non-aqueous solvents include carbonates such as ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate. Examples of supporting salts include fluorine-containing lithium salts such as lithium hexafluorophosphate (LiPF6). The electrolyte solution 15 is typically liquid, but may also be gel-like. Although not particularly limited, it is preferable that excess electrolyte solution 15 exists between the case 10 and the laminated electrode assembly 20. In this embodiment, the excess electrolyte solution 15 is stored in the gap GP.

[0020] <Laminated electrode body 20> The laminated electrode body 20 is housed inside the case main body 12. In this embodiment, two laminated electrode bodies 20 are housed inside one case main body 12. The two laminated electrode bodies 20 are arranged side by side in the thickness direction Y (see FIG. 5). The number of laminated electrode bodies 20 arranged inside one case main body 12 may be one, or may be three or more. The laminated electrode body 20 may be housed inside the case 10 covered with a resin insulating sheet (electrode body holder).

[0021] FIG. 3 is a cross-sectional view of the laminated electrode body 20. As shown in FIG. 3, the laminated electrode body 20 includes a plurality of positive electrode plates 22, a plurality of negative electrode plates 24 having a polarity opposite to that of the positive electrode plates 22, a separator 26, and adhesive layers 28 interposed between the positive electrode plates 22 and the separator 26 and between the negative electrode plates 24 and the separator 26 in the thickness direction Y. However, the adhesive layer 28 may be provided between the separator 26 and either one of the positive electrode plates 22 or the negative electrode plates 24. The positive electrode plates 22 and the negative electrode plates 24 face a pair of opposing side surface portions 12b (see FIG. 1) inside the cylindrical case body 12, and the positive electrode plates 22 and the negative electrode plates 24 are alternately arranged. The separator 26 is formed in a strip shape. The separator 26 is folded back in order and passes between the positive electrode plate 22 and the negative electrode plate 24 in order, thereby being disposed between the positive electrode plate 22 and the negative electrode plate 24. In other words, the separator 26 is folded in a so-called zigzag manner. The stacking direction of the multiple positive electrode plates 22 and the multiple negative electrode plates 24 is the thickness direction Y here. In the following description, the thickness direction Y will also be referred to as the stacking direction Y.

[0022] FIG. 4 is a schematic diagram showing the positive electrode plate 22 and the negative electrode plate 24. Note that the separator 26 (see FIG. 3) is not shown in FIG. 4. As shown in FIG. 4, a positive electrode active material layer 22b is formed on the positive electrode plate 22, and a negative electrode active material layer 24b is formed on the negative electrode plate 24. Therefore, in the stacked electrode body 20, the positive electrode plate 22 and the negative electrode plate 24 are stacked such that the positive electrode active material layer 22b and the negative electrode active material layer 24b face each other while being insulated from each other. The positive electrode active material layer 22b and the negative electrode active material layer 24b are insulated from each other by the separator 26 (see FIG. 3). In this embodiment, as shown in FIG. 3, the side surface of the stacked electrode body 20 to which a tape 29 (described later) is attached is referred to as the side surface 20Rr. In this embodiment, the rear surface of the stacked electrode body 20 is referred to as the side surface 20Rr. The front surface of the stacked electrode body 20 is referred to as the side surface 20F.

[0023] As shown in FIG. 4, the positive electrode plate 22 typically includes a positive electrode current collector foil 22a and a positive electrode active material layer 22b fixed to at least one surface (both surfaces in this example) of the positive electrode current collector foil 22a. The positive electrode current collector foil 22a is preferably a metal foil. In this embodiment, the positive electrode current collector foil 22a is made of, for example, aluminum or an aluminum alloy. The positive electrode active material layer 22b contains a positive electrode active material capable of reversibly absorbing and releasing charge carriers. The positive electrode active material may be a conventional material and is not particularly limited. An example of the positive electrode active material is a lithium transition metal composite oxide containing nickel, cobalt, and manganese. The positive electrode active material layer 22b may contain optional components other than the positive electrode active material, such as a binder or a conductive material. As shown in FIG. 3, both surfaces of the positive electrode plate 22 in the stacking direction Y are bonded to separators 26 via adhesive layers 28. As shown in FIG. 4, an uncoated portion 22c that does not have a positive electrode active material layer 22b is formed at one end in the width direction X of the positive electrode current collector foil 22a (here, the right side in the width direction X).

[0024] The negative electrode plate 24 typically includes a negative electrode current collector foil 24a and a negative electrode active material layer 24b fixed to at least one surface (here, both surfaces) of the negative electrode current collector foil 24a. The negative electrode current collector foil 24a is preferably a metal foil. In this embodiment, the negative electrode current collector foil 24a is made of, for example, copper or a copper alloy. The negative electrode active material layer 24b contains a negative electrode active material capable of reversibly absorbing and releasing charge carriers. The negative electrode active material may be a conventional material and is not particularly limited. Examples of negative electrode active materials include carbon materials such as graphite and silicon-based materials. The negative electrode active material layer 24b may contain optional components other than the negative electrode active material, such as a binder, a thickener, and a dispersant. As shown in FIG. 3 , both surfaces of the negative electrode plate 24 in the width direction X are bonded to separators 26 via adhesive layers 28. As shown in FIG. 4, in this embodiment, an uncoated portion 24c that does not have a negative electrode active material layer 24b is formed at one end in the width direction X of the negative electrode current collector foil 24a (here, the left side in the width direction X).

[0025] 3 is an insulating sheet having a plurality of fine through-holes formed therein through which charge carriers can pass. By interposing the separator 26 between the positive electrode plate 22 and the negative electrode plate 24, contact between the positive electrode plate 22 and the negative electrode plate 24 is prevented and charge carriers (e.g., lithium ions) can be transferred between the positive electrode plate 22 and the negative electrode plate 24. The thickness of the separator 26 is not particularly limited, but is about 20 μm in this embodiment.

[0026] As shown in FIG. 3 , the separator 26 has a first end 26e1 and a second end 26e2. The first end 26e1 is disposed on the outer periphery of the stacked electrode body 20, in which a plurality of positive electrode plates 22 and a plurality of negative electrode plates 24 are alternately arranged opposite each other. The second end 26e2 is disposed on the outer periphery of the stacked electrode body 20, in which a plurality of positive electrode plates 22 and a plurality of negative electrode plates 24 are alternately arranged opposite each other, and is overlapped on the outside of the first end 26e1 and fastened to the outer periphery of the stacked electrode body 20 with tape 29. The first end 26e1 and the second end 26e2 are located behind the portion where the positive electrode plates 22 and the negative electrode plates 24 are stacked. The first end 26e1 and the second end 26e2 are folded back at approximately right angles from the portion where the positive electrode plates 22 and the negative electrode plates 24 are stacked to the outer periphery and extend in the up-down direction Z. That is, the first end 26e1 and the second end 26e2 are formed in a substantially L-shape in side view. In FIG. 3 , a gap is formed between the first end 26e1 and the second end 26e2 in the thickness direction Y, but in reality, the gap is relatively narrow. In the portion fastened to the outer periphery of the stacked electrode body 20 with tape 29 (described later), the second end 26e2 of the separator 26 is longer than the first end 26e1. Therefore, the upper edge 26eU of the second end 26e2 is located higher than the first end 26e1. The portion of the stacked electrode body 20 where the first end 26e1 and the second end 26e2 are formed is thicker than other portions of the stacked electrode body 20 in the thickness direction Y by the thickness of the first end 26e1 and the second end 26e2. In this embodiment, the first end 26e1 and the second end 26e2 are formed in the lower portion of the stacked electrode body 20. Although not particularly limited, in this embodiment, the length of the first end 26e1 and the second end 26e2 in the vertical direction Z is approximately 3 to 10 mm. For convenience of explanation, the first end 26e1 and the second end 26e2 are illustrated in an exaggerated manner.

[0027] The separator 26 includes a resin separator substrate and one or more heat-resistant layers (HRLs) 26a containing a metal oxide such as alumina (Al2O3). In this embodiment, the separator 26 has the heat-resistant layer 26a formed on at least one surface. Here, the heat-resistant layer 26a is formed on the inside of the second end 26e2 of the separator 26 at a portion that is fastened to the outer periphery of the stacked electrode body 20 with tape 29, which will be described later.

[0028] The heat-resistant layer 26a typically contains an inorganic filler and a heat-resistant layer binder. The heat-resistant layer 26a suppresses thermal shrinkage of the separator 26, contributing to improved safety of the electricity storage device 100 (see FIG. 1). As the inorganic filler, ceramic particles such as alumina, zirconia, boehmite, aluminum hydroxide, silica, and titania are preferred, and from the viewpoint of suppressing thermal shrinkage of the separator 26, compounds containing aluminum are particularly preferred. As the heat-resistant layer binder, acrylic resins, fluorine-based resins, urethane resins, ethylene vinyl acetate resins, epoxy resins, and the like can be mentioned.

[0029] FIG. 6 is a rear view of the laminated electrode body 20. As described above, the tape 29 fastens the second end portion 26e2. As shown in FIG. 6, the tape 29 is composed of a first tape 29a, a second tape 29b, and a third tape 29c that are intermittently arranged along the upper edge 26eU of the second end portion 26e2. In this embodiment, the upper edge 26eU of the second end portion 26e2 extends in the width direction X. Therefore, the first tape 29a, the second tape 29b, and the third tape 29c are aligned along the width direction X. In this embodiment, the tape 29 is composed of the first tape 29a, the second tape 29b, and the third tape 29c, but the number of tapes that make up the tape 29 is not particularly limited. In the following description, unless otherwise specified, "tape 29" refers to the first tape 29a, the second tape 29b, and the third tape 29c. As shown in FIG. 5, in this embodiment, the upper end 29U of the tape 29 is positioned above the liquid surface 15a of the electrolyte solution 15. The thickness of the tape 29 is not particularly limited, but is approximately 50 μm in this embodiment. As shown in FIG. 3, the portion of the stacked electrode body 20 to which the tape 29 is fastened is formed to have a long length in the thickness direction Y of the stacked electrode body 20. The portion where the first end 26e1, the second end 26e2, and the tape 29 overlap in the stacking direction Y is the thickest portion of the stacked electrode body 20. In the following description, the portion of the stacked electrode body 20 where the first end 26e1, the second end 26e2, and the tape 29 overlap in the stacking direction Y is referred to as the "thickest portion."

[0030] FIG. 5 is a schematic diagram showing the inside of the case body 12. As shown in FIG. 5, the two stacked electrode bodies 20 are arranged side by side in the thickness direction Y. When the pair of opposing side surface portions 12b of the case body 12 is placed vertically, the upper edge 26eU of the second end portion 26e2 of the separator 26, which is fastened with tape 29, is positioned below the liquid level 15a of the electrolyte solution 15 outside the stacked electrode body 20 inside the case body 12. "When the pair of opposing side surface portions 12b are placed vertically" refers to the orientation when the case body 12 is placed so that one of the pair of narrow side surfaces (here, the bottom surface portion 12aa) is on the bottom side, and the pair of side surface portions 12b, which are the wider side surfaces, are approximately perpendicular to one of the pair of narrow side surfaces, as shown in FIG. 5. Here, the height of the liquid level 15a of the electrolyte solution 15 changes depending on the SOC (States of Charge) of the electricity storage device 100. In this embodiment, when the SOC of the electricity storage device 100 is 75% or higher, the upper edge 26eU of the second end 26e2 is located below the liquid level 15a of the electrolyte 15. That is, when the SOC of the electricity storage device 100 is 75% or higher, the first end 26e1 and the second end 26e2 of the separator 26, which are fastened with tape 29, are located below the liquid level 15a of the electrolyte 15. For convenience of explanation, a gap is shown between the stacked electrode body 20 and the side surface portion 12b in FIG. 5, but the stacked electrode body 20 and the side surface portion 12b may be in contact with each other. Note that "SOC of 75% or higher" refers to an SOC of 75% or higher when the electricity storage device 100 is new or relatively close to new.

[0031] 5, the side surfaces 20Rr of the two laminated electrode bodies 20 to which the tape 29 is attached are arranged facing the same side surface with respect to the pair of opposing side surface portions 12b of the case body 12. In this embodiment, the side surfaces 20Rr of the two laminated electrode bodies 20 are both arranged facing the side surface portion 12bb. Note that the side surfaces 20Rr of the two laminated electrode bodies 20 may also be arranged facing the side surface portion 12ba.

[0032] As shown in FIG. 2, the positive electrode plate 22 has a positive electrode tab 23 that extends toward the first sealing plate 14 and is connected to the positive electrode terminal 30. Each of the multiple positive electrode plates 22 has a positive electrode tab 23. The positive electrode tab 23 is a portion of the positive electrode current collector foil 22a (see FIG. 4) that protrudes from the region where the positive electrode active material layer 22b (see FIG. 4) and the negative electrode active material layer 24b (see FIG. 4) are overlapped. The positive electrode tab 23 is formed by overlapping the uncoated portion 22c (see FIG. 4). The positive electrode tab 23 is electrically connected to the positive electrode terminal 30 via the positive electrode current collector portion 32. The negative electrode plate 24 has a negative electrode tab 25 that extends toward the second sealing plate 16 and is connected to the negative electrode terminal 40. Each of the multiple negative electrode plates 24 has a negative electrode tab 25. The negative electrode tab 25 is a portion of the negative electrode current collector foil 24a (see FIG. 4) that protrudes from the region where the negative electrode active material layer 24b (see FIG. 4) and the negative electrode active material layer 24b (see FIG. 4) are overlapped. The negative electrode tab 25 is formed by overlapping the uncoated portion 24c (see FIG. 4). The negative electrode tab 25 is electrically connected to the negative electrode terminal 40 via the negative electrode current collector portion 42. The positive electrode tab 23 is an example of a first electrode tab in the present invention. The negative electrode tab 25 is an example of a second electrode tab in the present invention.

[0033] The adhesive layer 28 shown in Fig. 3 is interposed between the separator 26 and at least one of the positive electrode plate 22 and the negative electrode plate 24, bonding them together. This prevents misalignment of the positive electrode plate 22 and the negative electrode plate 24. This in turn prevents misalignment of the stacked electrode body 20. In Fig. 3, both surfaces of the positive electrode plate 22 and both surfaces of the negative electrode plate 24 are bonded to the opposing separators 26 via the adhesive layer 28 in the stacking direction Y.

[0034] The adhesive layer 28 is typically the layer containing the adhesive layer binder at the highest mass ratio. Examples of adhesive layer binders include fluorine-based resins, acrylic resins, urethane resins, ethylene vinyl acetate resins, and epoxy resins. The adhesive layer binder may be the same type as the heat-resistant layer binder described above, or may be a different type. The adhesive layer 28 may further contain other materials (e.g., inorganic fillers, etc.).

[0035] The configuration of the electricity storage device 100 according to this embodiment has been described above. When the electricity storage device 100 is charged and discharged, the positive electrode active material layer 22b (see FIG. 4) and the negative electrode active material layer 24b (see FIG. 4) expand and contract, causing the stacked electrode body 20 to expand and contract. When the stacked electrode body 20 expands, part of the electrolyte solution 15 impregnated in the stacked electrode body 20 is pushed out. When the stacked electrode body 20 contracts, part of the electrolyte solution 15 is absorbed into the stacked electrode body 20. If the thickness of the stacked electrode body 20 is not uniform, the force applied to the stacked electrode body 20 when it expands and contracts will not be uniform. If the extrusion and absorption of the electrolyte solution 15 is repeated at this time, there is a possibility that parts of the electricity storage device 100 will become deficient in the electrolyte solution 15 (so-called liquid starvation). When liquid starvation occurs, the battery characteristics of the electricity storage device 100 will deteriorate. The inventors of the present application wish to suppress the deterioration of battery characteristics when the extrusion and absorption of the electrolyte solution 15 is repeated.

[0036] Next, the electrolyte 15 inside the electricity storage device 100 when the electricity storage device 100 is charged and discharged will be described.

[0037] First, charging of the electricity storage device 100 will be described. The electricity storage device 100 is charged by a conventionally known method. FIG. 7 is a schematic diagram showing the inside of the case body 12 when the electricity storage device 100 is being charged. When the electricity storage device 100 is charged, the positive electrode active material layer 22b (see FIG. 4) and the negative electrode active material layer 24b (see FIG. 4) expand, as described above. As described above, the positive electrode plates 22 and the negative electrode plates 24 are stacked along the thickness direction Y. At this time, as shown in FIG. 7, the positive electrode plates 22 and the negative electrode plates 24 curve so as to expand toward the outside of the stacked electrode body 20. Therefore, the stacked electrode body 20 expands so as to expand in the thickness direction Y.

[0038] When the laminated electrode body 20 expands, the laminated electrode body 20 presses the pair of side surface portions 12b outward in the thickness direction Y. At this time, the laminated electrode body 20 receives a normal force from the pair of side surface portions 12b. Here, of the two laminated electrode bodies 20 lined up, the rearmost laminated electrode body 20 (hereinafter referred to as the "rear laminated electrode body 20") has its thickest portion facing the side surface portion 12bb, so the tape 29 comes into contact with the side surface portion 12bb. Furthermore, the side surface 20F of the rear laminated electrode body 20 comes into contact with the tape 29 of the frontmost laminated electrode body 20 (hereinafter referred to as the "front laminated electrode body 20") of the two laminated electrode bodies 20 lined up. Therefore, the rear laminated electrode body 20 is likely to be subjected to a force inward in the thickness direction Y near its thickest portion. Here, the vicinity of the thickest part refers to a range that includes at least one of the first end 26e1, the second end 26e2, and the tape 29 in the stacked electrode body 20. In this embodiment, the vicinity of the thickest part refers to the position of the upper end 29U of the tape 29 in the vertical direction Z in the stacked electrode body 20 and a range below the upper end 29U of the tape 29.

[0039] The tape 29 of the front laminated electrode body 20 is in contact with the rear laminated electrode body 20. The most expanding portion of the side surface 20F of the front laminated electrode body 20 is in contact with the side surface portion 12ba. Here, the side surface 20F is in contact with the side surface portion 12ba near the center in the vertical direction Z. Therefore, in the front laminated electrode body 20, the side surface 20F is likely to be subjected to a force inward in the thickness direction Y near the center in the vertical direction Z, while the side surface 20Rr is likely to be subjected to a force inward in the thickness direction Y near the thickest portion. Because the first end portion 26e1, the second end portion 26e2, and the tape 29 are absent in the region of the laminated electrode body 20 above the tape 29, the region of the laminated electrode body 20 is thinner in the thickness direction Y than the other regions of the laminated electrode body 20. Therefore, the region of the laminated electrode body 20 above the tape 29 is subjected to a relatively small force inward in the thickness direction Y.

[0040] When a force is applied to each of the two stacked electrode bodies 20 inward in the thickness direction Y, the electrolyte 15 impregnated in the stacked electrode bodies 20 is pushed out. Because the stacked electrode bodies 20 are pushed inward in the thickness direction Y, the electrolyte 15 is pushed outward in the width direction X. In this embodiment, because the force is applied near the thickest part of the stacked electrode body 20, the electrolyte 15 impregnated near the thickest part is easily pushed out. The pushed-out electrolyte 15 is stored inside the case body 12. More specifically, the pushed-out electrolyte 15 is stored in the lower part of the case body 12 due to gravity. Therefore, as shown in FIG. 2, the electrolyte 15 is stored in the lower part of the case body 12. At this time, the electrolyte 15 is also stored in the gaps GP (see FIG. 2) on the right and left sides of the stacked electrode body 20. In the region above the tape 29 in the laminated electrode body 20, the force acting inward in the thickness direction Y is relatively small, so the electrolyte 15 is less likely to be pushed out than in the vicinity of the thickest part.

[0041] Next, the discharge of the electricity storage device 100 will be described. The electricity storage device 100 is discharged, for example, when a vehicle (not shown) equipped with the electricity storage device 100 is running. FIG. 8 is a schematic diagram showing the inside of the case body 12 when the electricity storage device 100 is being discharged. When the electricity storage device 100 is discharged, the positive electrode active material layer 22b (see FIG. 4) and the negative electrode active material layer 24b (see FIG. 4) contract as described above. At this time, as shown in FIG. 8, the positive electrode plate 22 and the negative electrode plate 24 curve inward in the thickness direction Y. Therefore, the stacked electrode body 20 contracts in the thickness direction Y.

[0042] When the laminated electrode body 20 contracts, the electrolyte solution 15 stored inside the case main body 12 is absorbed by the laminated electrode body 20. In this embodiment, the separator 26 is attached so as to cover the positive electrode plate 22 and the negative electrode plate 24 in the thickness direction Y. Therefore, the positive electrode plate 22 and the negative electrode plate 24 are not covered by the separator 26 in the width direction X. Therefore, the laminated electrode body 20 mainly absorbs the electrolyte solution 15 stored in the gaps GP (see FIG. 2 ) on the left and right sides of the laminated electrode body 20. Because the electrolyte solution 15 is stored in the lower part of the case main body 12, it is absorbed from the lower part of the laminated electrode body 20. When the lower part of the laminated electrode body 20 can no longer absorb all the electrolyte solution 15, the electrolyte solution 15 is gradually absorbed by the upper part of the laminated electrode body 20.

[0043] Furthermore, the gap between the first end 26e1 and the second end 26e2 is relatively narrow. Therefore, as the electrolyte solution 15 is absorbed into the upper portion of the stacked electrode body 20, the electrolyte solution 15 that has entered between the first end 26e1 and the second end 26e2 is absorbed toward the positive electrode plate 22 and the negative electrode plate 24. That is, as shown by the arrows in FIG. 8 , the electrolyte solution 15 disposed between the first end 26e1 and the second end 26e2 passes through the approximately right-angled portion between the first end 26e1 and the second end 26e2 and moves toward the positive electrode plate 22 and the negative electrode plate 24 due to capillary action.

[0044] As described above, in the electricity storage device 100 of this embodiment, the case body 12 accommodates the stacked electrode body 20 and the electrolyte 15. The stacked electrode body 20 is formed by stacking positive electrode plates 22 and negative electrode plates 24, and the separator 26 is sandwiched between the positive electrode plates 22 and the negative electrode plates 24 and folded back. The positive electrode plates 22 and the negative electrode plates 24 face a pair of opposing side surface portions 12b inside the cylindrical case body 12, and the positive electrode plates 22 and the negative electrode plates 24 are arranged alternately. When the electricity storage device 100 is charged and discharged, the electrolyte 15 impregnated in the stacked electrode body 20 is pushed out or absorbed mainly in the width direction X. That is, when the electricity storage device 100 is charged and discharged, the electrolyte 15 is pushed out into the gaps GP, and the electrolyte 15 stored in the gaps GP is absorbed by the stacked electrode body 20. The laminated electrode body 20 has a first end 26e1 and a second end 26e2. Tape 29 is attached to the second end 26e2. Therefore, when the electricity storage device 100 is charged and the laminated electrode body 20 expands and contacts the pair of side surface portions 12b, a relatively large force is applied to the laminated electrode body 20 near the thickest portion. Therefore, the electrolyte 15 is easily extruded from the laminated electrode body 20 near the thickest portion. Furthermore, the upper edge 26eU of the second end 26e2 is positioned below the liquid level 15a of the electrolyte 15. Therefore, all or part of the vicinity of the thickest portion is immersed in the electrolyte 15. Therefore, when the laminated electrode body 20 contracts after the electrolyte 15 is extruded from the vicinity of the thickest portion, the electrolyte 15 is easily absorbed from the vicinity of the thickest portion. That is, in the laminated electrode body 20, the areas where the electrolyte 15 is likely to be pushed out during charging and the areas where the electrolyte 15 is likely to be absorbed during discharging are the same. This prevents the occurrence of liquid depletion in the laminated electrode body 20. Therefore, in the electricity storage device 100, deterioration of the battery characteristics due to liquid depletion during charging and discharging is prevented.

[0045] In the electricity storage device 100 of this embodiment, the upper end 29U of the tape 29 is positioned above the liquid level 15a of the electrolyte 15. As a result, the electrolyte 15 contained in the area sandwiched between the first end 26e1 and the second end 26e2 does not flow from between the separator 26 and the tape 29, but flows downward from the tape 29 as shown by the arrows in FIG. 8 and is absorbed into the positive electrode plate 22 and the negative electrode plate 24. As a result, the absorbed electrolyte 15 circulates relatively easily inside the stacked electrode body 20.

[0046] In the electricity storage device 100 of this embodiment, as shown in FIG. 6 , the tape 29 is intermittently arranged along the upper edge 26eU of the second end 26e2. As a result, when the electricity storage device 100 is charged, the normal force received from the case body 12 differs between the portions of the second end 26e2 where the tape 29 is fastened and the portions where the tape 29 is not fastened. That is, a greater force is applied to the portions where the tape 29 is fastened than to the portions where the tape 29 is not fastened. As a result, when the stacked electrode body 20 expands and contracts due to charging and discharging of the electricity storage device 100, a pressure difference occurs between the portions of the second end 26e2 where the tape 29 is fastened and the portions where the tape 29 is not fastened. This pressure difference serves as a driving force to move the electrolyte solution 15 inside the stacked electrode body 20. Therefore, the occurrence of this pressure difference makes it easier for the electrolyte solution 15 to spread inside the stacked electrode body 20. Therefore, in the electricity storage device 100, liquid depletion due to charging and discharging is further suppressed.

[0047] In the power storage device 100 of this embodiment, the second end 26e2 is formed to be longer than the first end 26e1 in the vertical direction Z. Therefore, the second end 26e2 is fastened so as to cover the first end 26e1 above the upper end of the first end 26e1. This prevents the separator 26 from loosening.

[0048] According to the electricity storage device 100 of this embodiment, the heat-resistant layer 26a is formed on the inner side of the second end portion 26e2. The second end portion 26e2 forms the outermost portion of the separator 26. Therefore, by forming the heat-resistant layer 26a on the inner side of the second end portion 26e2, even if a short circuit occurs inside the stacked electrode body 20, it is possible to suppress the spread of fire.

[0049] In the electricity storage device 100 of this embodiment, when the SOC of the electricity storage device 100 is 75% or higher, the first end 26e1 and the second end 26e2 are located below the liquid level 15a of the electrolyte solution 15. When the electricity storage device 100 is charged or discharged, the electrolyte solution 15 impregnated in the stacked electrode body 20 flows in and out of the inside of the case body 12, and the height of the liquid level 15a of the electrolyte solution 15 changes during charging and discharging. The inventors of the present application have found that by setting the SOC of the electricity storage device 100 to 75% or higher when the first end 26e1 and the second end 26e2 are located below the liquid level 15a of the electrolyte solution 15, the electrolyte solution 15 is absorbed from the vicinity of the thickest part of the electricity storage device 100, and liquid depletion is suppressed. Therefore, when the SOC of the electricity storage device 100 is 75% or more, the first end 26e1 and the second end 26e2 are positioned below the liquid level 15a of the electrolyte solution 15, which is a specific embodiment that can achieve the effects of the present invention.

[0050] According to the electricity storage device of this embodiment, when the pair of side portions 12b is placed vertically, the upper edges 26eU of the second ends 26e2 of the two stacked electrode bodies 20 are positioned below the liquid level 15a of the electrolyte 15. Therefore, even when the electricity storage device 100 has a plurality of stacked electrode bodies 20, it is possible to prevent the liquid from drying up in each of the stacked electrode bodies 20.

[0051] In the electricity storage device 100 of this embodiment, the side surfaces 20Rr of the two stacked electrode bodies 20 are both arranged facing the side surface portion 12ba. Therefore, the separators 26 are folded back in the same direction in the two stacked electrode bodies 20. Therefore, in manufacturing the electricity storage device 100, it is sufficient to prepare two stacked electrode bodies 20 in which the separators 26 are folded back in the same direction. This reduces the burden during manufacturing of the electricity storage device 100, and the productivity of the electricity storage device 100 can be improved.

[0052] In the power storage device 100 of this embodiment, the positive electrode tab 23 extends toward the first sealing plate 14 and is connected to the positive electrode terminal 30. The positive electrode terminal 30 is provided on the first sealing plate 14. The negative electrode tab 25 extends toward the second sealing plate 16 and is connected to the negative electrode terminal 40. The negative electrode terminal 40 is provided on the second sealing plate 16. Therefore, in this embodiment, the first sealing plate 14, the positive electrode terminal 30, the positive electrode tab 23, the second sealing plate 16, the negative electrode terminal 40, and the negative electrode tab 25 are aligned in the width direction X. By aligning these in the width direction X, the length of the stacked electrode body 20 in the up-down direction Z can be made relatively uniform. This allows the length of the case body 12 in the up-down direction Z to be close to the length of the stacked electrode body 20 in the up-down direction Z, and the filling rate of the stacked electrode body 20 in the case body 12 can be made relatively high. This allows the extruded electrolyte 15 to relatively easily accumulate in the gap GP. The electrolyte solution 15 stored in the gap GP is absorbed when the electricity storage device 100 discharges. Therefore, the electrolyte solution 15 circulates between the inside and outside of the stacked electrode body 20 relatively easily.

[0053] The above describes the power storage device 100 according to the first embodiment. However, the above-described first embodiment is merely an example, and the present invention can be embodied in various other forms.

[0054] Second Embodiment 9 is a schematic diagram showing the inside of an electricity storage device 100A according to a second embodiment. In the following description of the second embodiment, components that perform the same functions as those in the first embodiment will be designated by the same reference numerals as those in the first embodiment. Further, duplicated descriptions will be omitted or simplified. The same applies to the third and fourth embodiments described below.

[0055] As shown in FIG. 9, in the second embodiment, an upper end 29U of a tape 29 is disposed below a liquid surface 15a of the electrolyte solution 15. In the second embodiment, as shown in FIG.

[0056] When the electricity storage device 100A is charged, a large force is applied to the stacked electrode body 20 near the thickest part, as in the first embodiment. Therefore, the electrolyte 15 impregnated in the stacked electrode body 20 near the thickest part is pushed out. Furthermore, because the upper end 29U of the tape 29 is positioned below the liquid level 15a of the electrolyte 15, the vicinity of the thickest part of the stacked electrode body 20 is located below the liquid level 15a of the electrolyte 15. When the electricity storage device 100 is discharged, the stacked electrode body 20 contracts and the electrolyte 15 is absorbed, as in the first embodiment.

[0057] In the second embodiment described above, the upper end 29U of the tape 29 is positioned below the liquid level 15a of the electrolyte solution 15. Here, the laminated electrode body 20 receives pressure from the electrolyte solution 15 below the liquid level 15a of the electrolyte solution 15. In the present embodiment, because the upper end 29U is positioned below the liquid level 15a of the electrolyte solution 15, a relatively large portion of the laminated electrode body 20 is immersed in the electrolyte solution 15. Therefore, the pressure from the electrolyte solution 15 is applied to a relatively large region of the laminated electrode body 20. As a result, the electrolyte solution 15 impregnated in the laminated electrode body 20 is relatively easily pushed upward toward the laminated electrode body 20. This prevents the electrolyte solution 15 from drying up inside the laminated electrode body 20.

[0058] Third Embodiment FIG. 10 is a schematic diagram showing the interior of an electricity storage device 100B according to the third embodiment. As shown in FIG. 10, a stacked electrode body 20B and a stacked electrode body 21B are accommodated inside the case 10. The stacked electrode body 20B is disposed forward of the stacked electrode body 21B. The side surface of the stacked electrode body 20B to which the tape 29 is attached is designated as 20BF. The side surface of the stacked electrode body 20B opposite the side surface 20BF ​​in the thickness direction Y is designated as 20Br. The side surface of the stacked electrode body 21B to which the tape 29 is attached is designated as 21Br. The side surface of the stacked electrode body 21B opposite the side surface 21Br in the thickness direction Y is designated as 21BF. The side surface 20BF ​​is located on the front surface of the stacked electrode body 20B, and the side surface 20Br is located on the rear surface of the stacked electrode body 20B. The side surface 21BF is located on the front surface of the laminated electrode body 20, and the side surface 21Br is located on the rear surface of the laminated electrode body 21B. Therefore, the laminated electrode body 20B and the laminated electrode body 21B differ in the way the separator 26 is folded. In the laminated electrode body 20B, the separator 26 is folded with the first end 26e1 and the second end 26e2 positioned in front of the positive electrode plate 22 and the negative electrode plate 24. In the laminated electrode body 21B, the separator 26 is folded with the first end 26e1 and the second end 26e2 positioned behind the positive electrode plate 22 and the negative electrode plate 24.

[0059] In the third embodiment, of the stacked electrode body 20 arranged at a position facing a pair of opposing side surface portions 12b of the case body 12, the side surfaces to which the tape 29 is attached are arranged so as to face the side surface portions 12b of the case body 12. More specifically, the side surface 20BF ​​of the stacked electrode body 20B is arranged so as to face the side surface portions 12ba, and the side surface 21Br of the stacked electrode body 21B is arranged so as to face the side surface portions 12bb.

[0060] When the electricity storage device 100B is charged and the stacked electrode body 20B and the stacked electrode body 21B each expand in the thickness direction Y, the tape 29 attached to the side surface 20BF ​​of the stacked electrode body 20B comes into contact with the side surface portion 12ba and receives a normal force from the side surface portion 12ba. The tape 29 attached to the side surface 21Br of the stacked electrode body 21B comes into contact with the side surface portion 12bb and receives a normal force from the side surface portion 12bb. At this time, the side surface 20Br of the stacked electrode body 20B and the side surface 21BF of the stacked electrode body 21B come into contact and press against each other. At this time, the electrolyte 15 impregnated in the stacked electrode body 20B and the stacked electrode body 21B is pushed out.

[0061] According to the third embodiment described above, the tape 29 of the laminated electrode body 20B and the tape 29 of the laminated electrode body 21B are subjected to normal forces from the pair of opposing side surfaces 12b. Therefore, the laminated electrode body 20B and the laminated electrode body 21B are arranged so that the vicinity of the thickest portion of the laminated electrode body 20B and the vicinity of the thickest portion of the laminated electrode body 21B are likely to receive forces from the pair of opposing side surfaces 12b. This increases the amount of electrolyte 15 extruded and the amount of electrolyte 15 absorbed, which facilitates circulation of the electrolyte 15 inside and outside the laminated electrode body 20B and the laminated electrode body 21B. This prevents the electrolyte 15 from drying up inside and outside the laminated electrode body 20B and the laminated electrode body 21B.

[0062] Fourth Embodiment FIG. 11 is a schematic diagram showing the inside of an electricity storage device 100C according to the fourth embodiment. As shown in FIG. 11, a stacked electrode body 20C and a stacked electrode body 21C are housed inside a case 10. The stacked electrode body 20C is disposed forward of the stacked electrode body 21C. The side of the stacked electrode body 20C to which the tape 29 is attached is referred to as 20Cr. The side of the stacked electrode body 20C opposite the side surface 20Cr in the thickness direction Y is referred to as a side surface 20CF. The side of the stacked electrode body 21C to which the tape 29 is attached is referred to as 21CF. The side surface 20Cr is located on the rear surface of the stacked electrode body 20C, and the side surface 20CF is located on the front surface of the stacked electrode body 20C. The side surface 21CF is located on the front surface of the laminated electrode body 21C, and the side surface 21Cr is located on the rear surface of the laminated electrode body 21C. Therefore, the laminated electrode body 20C and the laminated electrode body 21C differ in the way the separator 26 is folded. In the laminated electrode body 20C, the separator 26 is folded with the first end 26e1 and the second end 26e2 positioned behind the positive electrode plate 22 and the negative electrode plate 24. In the laminated electrode body 21C, the separator 26 is folded with the first end 26e1 and the second end 26e2 positioned in front of the positive electrode plate 22 and the negative electrode plate 24.

[0063] In the fourth embodiment, the side surfaces of the laminated electrode body 20C and the laminated electrode body 21C to which the tape 29 is attached face opposite the pair of opposing side surface portions 12b of the case body 12. More specifically, the side surface 20Cr of the laminated electrode body 20C is disposed on the opposite side of the side surface portion 12ba in the thickness direction Y. The side surface 21CF of the laminated electrode body 21C is disposed on the opposite side of the side surface portion 12bb in the thickness direction Y. Therefore, the side surface 20Cr and the side surface 21CF face each other.

[0064] When the electricity storage device 100C is charged and the stacked electrode body 20C and the stacked electrode body 21C each expand in the thickness direction Y, the side surface 20CF of the stacked electrode body 20C comes into contact with the side surface portion 12ba and receives a normal force from the side surface portion 12ba. Furthermore, the side surface 21Cr of the stacked electrode body 21C comes into contact with the side surface portion 12bb and receives a normal force from the side surface portion 12bb. At this time, the tape 29 of the stacked electrode body 20C and the tape 29 of the stacked electrode body 21C come into contact with each other, and a force is applied in the thickness direction Y to the vicinity of the thickest portions of the stacked electrode body 20C and the stacked electrode body 21C. Therefore, at this time, the electrolyte 15 impregnated in the stacked electrode body 20C and the stacked electrode body 21C is pushed out.

[0065] According to the fourth embodiment described above, the stacked electrode body 20C receives a normal force from the side surface portion 12ba, and the stacked electrode body 21C receives a normal force from the side surface portion 12bb. As a result, the tape 29 of the stacked electrode body 20C and the tape 29 of the stacked electrode body 21C are pressed in the thickness direction Y, and the vicinity of the thickest portions of the stacked electrode body 20C and the stacked electrode body 21C are pressed. Furthermore, the side surface 20CF of the stacked electrode body 20C and the side surface 21Cr of the stacked electrode body 21C are relatively flat because the tape 29 is not attached thereto. Therefore, the force applied to the side surface 20CF and the side surface 21Cr is relatively unlikely to vary depending on the position in the vertical direction Z. Therefore, when the stacked electrode body 20C and the stacked electrode body 21C expand and come into contact with the pair of side surface portions 12b, the normal force applied from the pair of side surface portions 12b is unlikely to be resolved in directions other than the thickness direction Y. As a result, the amounts of electrolyte solution 15 extruded from the stacked electrode body 20C and the stacked electrode body 21C and the amounts of electrolyte solution 15 absorbed into the stacked electrode body 20C and the stacked electrode body 21C are relatively large. Circulation of the electrolyte solution 15 is likely to occur inside and outside the stacked electrode body 20C and the stacked electrode body 21C. This prevents the electrolyte solution 15 from drying up inside and outside the stacked electrode body 20C and the stacked electrode body 21C.

[0066] The invention disclosed herein has been described in various ways. Unless otherwise specified, the embodiments described herein do not limit the present invention. Furthermore, the embodiments of the invention disclosed herein can be modified in various ways, and each component and each process described herein can be omitted or combined as appropriate, unless a particular problem arises.

[0067] As described above, this specification includes the disclosures set forth in the following sections.

[0068] Section 1: an electrode assembly including a plurality of first electrode plates, a plurality of second electrode plates having a polarity different from that of the first electrode plates, and a separator; An electrolyte; a cylindrical case body that accommodates the electrode assembly and the electrolyte; a first sealing plate attached to an opening on a first side of the case body; a second sealing plate attached to the opening on the second side of the case body; and A secondary battery comprising: The case body has a pair of opposing side surfaces, the plurality of first electrode plates and the plurality of second electrode plates face the pair of opposing side surface portions inside the case body, and the first electrode plates and the second electrode plates are alternately arranged; the separator is in a strip shape, and is folded back in order to pass between the first electrode plate and the second electrode plate in order, thereby being disposed between the first electrode plate and the second electrode plate; The first end of the separator is the plurality of first electrode plates and the plurality of second electrode plates are arranged on the outer periphery of the electrode body so as to face each other alternately; The second end of the separator is the plurality of first electrode plates and the plurality of second electrode plates are arranged on the outer periphery of the electrode body so as to face each other alternately, and are overlapped on the outside of the first end portion and fastened to the outer periphery of the electrode body with tape; When the pair of opposing side surfaces of the case body are placed vertically, the upper edge of the second end of the separator fastened with the tape is positioned below the liquid level of the electrolyte outside the electrode body in the case body. Secondary battery.

[0069] Section 2: Item 2. The secondary battery according to item 1, wherein an upper end of the tape is disposed above the liquid surface of the electrolyte.

[0070] Section 3: Item 2. The secondary battery according to item 1, wherein an upper end of the tape is disposed below the liquid surface of the electrolyte.

[0071] Section 4: 4. The secondary battery according to any one of items 1 to 3, wherein the tape is composed of a plurality of tapes arranged intermittently along the upper edge of the second end portion.

[0072] Section 5: 5. The secondary battery according to any one of items 1 to 4, wherein the second end of the separator is longer than the first end in the portion fastened to the outer periphery of the electrode assembly with the tape.

[0073] Item 6: 6. The secondary battery according to any one of items 1 to 5, wherein the second end of the separator has a heat-resistant layer formed on the inside of the electrode body at a portion fastened to the outer periphery of the electrode body with the tape.

[0074] Section 7: 7. The secondary battery according to any one of items 1 to 6, wherein, when the pair of opposing side surfaces of the case body are placed vertically in a state of SOC 75% or more, the first end and the second end of the separator fastened with the tape are positioned below the liquid surface of the electrolyte outside the electrode body.

[0075] Section 8: a plurality of the electrode bodies are arranged facing each other along the pair of facing side surfaces of the case body, 8. The secondary battery according to any one of items 1 to 7, wherein when the pair of opposing side surfaces of the case body are placed vertically, the upper edge of the second end of the separator fastened with the tape is positioned below the liquid level of the electrolyte outside the electrode body inside the case body.

[0076] Section 9: The secondary battery according to any one of items 1 to 8, wherein the sides of the electrode body to which the tape is attached are arranged facing the same sides of the pair of opposing side portions of the case body.

[0077] Section 10: The secondary battery according to any one of items 1 to 8, wherein the electrode bodies arranged at positions facing the pair of opposing side surface portions of the case body have the sides to which the tape is attached facing the side surface of the case body.

[0078] Section 11: Item 9. The secondary battery according to any one of items 1 to 8, wherein the side of the electrode body to which the tape is attached faces away from the pair of opposing side portions of the case body.

[0079] Section 12: a first terminal provided on the first sealing plate; the plurality of first electrode plates each have a first electrode tab extending toward the first sealing plate and connected to the first terminal; a second terminal provided on the second sealing plate; The plurality of second electrode plates each have a second electrode tab extending toward the second sealing plate and connected to the second terminal. 12. The secondary battery according to any one of items 1 to 11. [Explanation of symbols]

[0080] 10 cases 12 Case body 12a Bottom part 12b Side part 12d Top section 12e1,12e2 End 12h1 First side opening 12h2 Second side opening 15 Electrolyte 15a Liquid level 20. Laminated electrode body 20F,20Rr side 20B, 21B Laminated electrode body 20BF,20Br side 21BF,21Br Side 20C, 21C laminated electrode body 20CF,20Cr side 21CF,21Cr side 22 Positive electrode plate 22a Positive electrode current collector foil 22b Positive electrode active material layer 22c Uncoated area 23 Positive electrode tab 24 negative electrode plate 24a Negative current collector foil 24b Negative electrode active material layer 24c Uncoated area 25 Negative electrode tab 26 Separator 26a Heat-resistant layer 26eU upper edge 28 Adhesive layer 29 Tape 29U top end 30 Positive terminal 32 Positive electrode current collector 40 Negative terminal 42 Negative electrode current collector 100 Energy storage device 100A power storage device 100B Energy Storage Device 100C Energy Storage Device GP Gap

Claims

1. an electrode assembly including a plurality of first electrode plates, a plurality of second electrode plates having a polarity different from that of the first electrode plates, and a separator; An electrolyte; a cylindrical case body that accommodates the electrode assembly and the electrolyte; a first sealing plate attached to an opening on a first side of the case body; a second sealing plate attached to the opening on the second side of the case body; A secondary battery comprising: The case body has a pair of opposing side surfaces, the plurality of first electrode plates and the plurality of second electrode plates face the pair of opposing side surface portions inside the case body, and the first electrode plates and the second electrode plates are alternately arranged; the separator is in a strip shape, and is folded back in order to pass between the first electrode plate and the second electrode plate in order, thereby being disposed between the first electrode plate and the second electrode plate; The first end of the separator comprises: the plurality of first electrode plates and the plurality of second electrode plates are arranged on the outer periphery of the electrode body so as to face each other alternately; The second end of the separator is the plurality of first electrode plates and the plurality of second electrode plates are arranged on the outer periphery of the electrode body so as to face each other alternately, and are overlapped on the outside of the first end portion and fastened to the outer periphery of the electrode body with tape; When the pair of opposing side surfaces of the case body are placed vertically, the upper edge of the second end of the separator fastened with the tape is positioned below the liquid level of the electrolyte outside the electrode body in the case body. Secondary battery.

2. The secondary battery according to claim 1 , wherein an upper end of the tape is disposed above the liquid surface of the electrolyte.

3. The secondary battery according to claim 1 , wherein an upper end of the tape is disposed below the liquid surface of the electrolyte.

4. The secondary battery according to claim 1 , wherein the tape is made up of a plurality of tapes arranged intermittently along the upper edge of the second end portion.

5. The secondary battery according to claim 1 , wherein the second end of the separator is longer than the first end at the portion fastened to the outer periphery of the electrode assembly with the tape.

6. The secondary battery according to claim 1 , wherein the second end of the separator has a heat-resistant layer formed on the inner side of the electrode body in a portion fastened to the outer periphery of the electrode body with the tape.

7. 2. The secondary battery according to claim 1, wherein, when the pair of opposing side surfaces of the case body are placed vertically in a state of SOC 75% or higher, the first end and the second end of the separator fastened with the tape are positioned below the liquid surface of the electrolyte outside the electrode body.

8. a plurality of the electrode bodies are arranged facing each other along the pair of facing side surfaces of the case body, 2. The secondary battery according to claim 1, wherein, when the pair of opposing side surfaces of the case body are placed vertically, the upper edge of the second end of the separator fastened with the tape is positioned below the liquid level of the electrolyte outside the electrode body inside the case body.

9. The secondary battery according to claim 1 , wherein the sides of the electrode body to which the tape is attached are arranged facing the same side of the pair of opposing side portions of the case body.

10. 2. The secondary battery according to claim 1, wherein the electrode bodies arranged at positions facing the pair of opposing side portions of the case body have the sides to which the tape is attached facing the side portions of the case body.

11. The secondary battery according to claim 1 , wherein the side of the electrode body to which the tape is attached faces away from the pair of opposing side surfaces of the case body.

12. a first terminal provided on the first sealing plate; a second terminal provided on the second sealing plate, the plurality of first electrode plates each have a first electrode tab extending toward the first sealing plate and connected to the first terminal; The plurality of second electrode plates each have a second electrode tab extending toward the second sealing plate and connected to the second terminal. The secondary battery according to claim 1 .

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