Energy storage devices

Abstract

To provide an energy storage device that can also increase heat conduction from one side R portion of multiple flat wound electrode bodies to the third case wall portion of the case. [Solution] The energy storage device 1 comprises a plurality of flat wound electrode bodies 30 and a case 10 that houses them. The case 10 has a flat plate-shaped first case wall portion 11 that contacts the plurality of flat wound electrode bodies 30 from one side FH1 in the electrode body thickness direction FH, a flat plate-shaped second case wall portion 12 that contacts the plurality of flat wound electrode bodies 30 from the other side FH2 in the electrode body thickness direction FH, and a third case wall portion 13 in which the same number of one-sided semi-cylindrical inner wall surfaces 13n as the number of flat wound electrode bodies 30 are arranged in the electrode body thickness direction FH, forming a semi-cylindrical surface along the outer peripheral surface 32r of one-sided R portion 32 of the flat wound electrode body 30 and contacting the outer peripheral surface 32r.

Description

[Technical Field]

[0001] The present invention relates to an electricity storage device (such as a battery or a capacitor) in which a plurality of flat wound electrode assemblies are housed in a metal case. [Background Art]

[0002] Conventionally, batteries in which a plurality of flat wound electrode assemblies are housed in a rectangular parallelepiped box-shaped metal case have been known. In this battery, the plurality of flat wound electrode assemblies are stacked in the electrode assembly thickness direction with their winding axes parallel to each other, and are further housed in the case while being covered by an insulating holder made of an insulating film. As related prior art, Patent Document 1 can be mentioned, for example (see FIG. 2 and FIG. 3 of Patent Document 1). [Prior Art Documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Unexamined Patent Publication No. 2024-175222 [Summary of the Invention] [Problem to be Solved by the Invention]

[0004] The flat wound electrode assembly is formed by flatly winding positive and negative strip-shaped electrode plates, and includes a rectangular parallelepiped electrode main body, and a pair of semi-cylindrical R portions (one-side R portion and the other-side R portion) respectively positioned on both sides of the electrode main body. In the aforementioned battery, the opposing first case wall and second case wall of the case are respectively in contact with the stacked plurality of flat wound electrode assemblies via the aforementioned insulating holder. On the other hand, among the plurality of flat wound electrode assemblies, the case is not in contact with each one-side R portion and each other-side R portion, and a space is formed between these R portions and the case. For this reason, in conventional batteries, heat conduction from the flat wound electrode assemblies to the first case wall and the second case wall of the case is high, but heat conduction from the one-side R portion and the other-side R portion of the flat wound electrode assemblies to the case is low.

[0005] The present invention has been made in view of the current situation, and provides an energy storage device comprising a plurality of flat wound electrode bodies that not only provides high thermal conductivity from the plurality of flat wound electrode bodies to the first and second case walls of the case, but also provides high thermal conductivity from one side R portion of the plurality of flat wound electrode bodies to the third case wall of the case. [Means for solving the problem]

[0006] (1) One aspect of the present invention for solving the above problems is an energy storage device comprising: a metal case; and a plurality of flat wound electrode bodies, each of which has a winding axis parallel to the others and is housed in the case in a stacked state in the electrode body thickness direction, wherein the case has a flat plate shape perpendicular to the electrode body thickness direction and a first case wall portion that directly or indirectly contacts the stacked plurality of flat wound electrode bodies from one side in the electrode body thickness direction; and a flat plate shape perpendicular to the electrode body thickness direction and facing the first case wall portion, which contacts the stacked plurality of flat wound electrode bodies from the front in the electrode body thickness direction. The energy storage device comprises a second case wall portion that directly or indirectly contacts the first case wall portion from the opposite side to the first case wall portion, and a third case wall portion that connects the first case wall portion and the second case wall portion and is located on one side in the electrode width direction perpendicular to the winding axis and the electrode thickness direction, wherein the third case wall portion forms a semi-cylindrical surface that is convex to the one side in the electrode width direction along the outer circumferential surface of the semi-cylindrical one-side R portion located on one side in the electrode width direction of the flat wound electrode body, and the same number of one-side semi-cylindrical inner wall surfaces as the flat wound electrode body that directly or indirectly contact the outer circumferential surface of the one-side R portion are arranged in the electrode thickness direction.

[0007] In the energy storage device described above, the third case wall of the case has a shape in which multiple semi-cylindrical inner wall surfaces, each forming a semi-cylindrical surface, are arranged in a row. Furthermore, the first and second case walls of the case are not only in contact with multiple stacked flat wound electrode bodies, but the third case wall of the case is also in contact with the R-shaped portion on one side of each of the multiple flat wound electrode bodies. As a result, not only is the heat conduction from the multiple flat wound electrode bodies to the first and second case walls of the case high, but the heat conduction from the R-shaped portion on one side of each flat wound electrode body to the third case wall of the case can also be increased. Therefore, this energy storage device can be cooled more effectively.

[0008] (2) A further energy storage device as described in (1), wherein the case has a fourth case wall portion that connects the first case wall portion and the second case wall portion, is located on the other side opposite to the one side in the electrode width direction, and faces the third case wall portion, and the fourth case wall portion has a semi-cylindrical surface that is convex to the other side in the electrode width direction, along the outer circumferential surface of the semi-cylindrical other side R portion located on the other side in the electrode width direction of the flat wound electrode body, and the same number of other side semi-cylindrical inner wall surfaces that directly or indirectly contact the outer circumferential surface of the flat wound electrode body are arranged in the electrode thickness direction.

[0009] (3) The energy storage device described in (1) is further provided, wherein the case is made of an extruded material and comprises a cylindrical case body which integrally includes the first case wall, the second case wall, and the third case wall, and a pair of lids which close a pair of openings located at both ends of the case body.

[0010] (4) The energy storage device described in (2) is further described, wherein the case is made of an extruded material and comprises a cylindrical case body which integrally includes the first case wall, the second case wall, the third case wall, and the fourth case wall, and a pair of lids which close a pair of openings located at both ends of the case body. [Brief explanation of the drawing]

[0011] [Figure 1] This is a perspective view of the battery according to Embodiment 1. [Figure 2] This is a cross-sectional view taken along the battery height direction and the battery thickness direction of the battery according to Embodiment 1, shown in Figure 3, along line II-II. [Figure 3] This is a partially fractured cross-sectional view of the battery according to Embodiment 1, along the battery height direction and the battery width direction. [Figure 4] This is a cross-sectional view of the battery according to Embodiment 2, along the battery height direction and the battery thickness direction, corresponding to Figure 2. [Modes for carrying out the invention]

[0012] (Embodiment 1) Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. The battery 1 of this first embodiment (an example of an energy storage device) (see Figures 1 to 3) is a sealed lithium-ion secondary battery installed in vehicles such as hybrid cars, plug-in hybrid cars, and electric vehicles. In the following description, the battery height direction AH, the battery width direction BH, and the battery thickness direction CH of the battery 1 are defined as the directions shown in Figures 1 to 3.

[0013] This battery 1 consists of a metal case (aluminum in this embodiment 1) 10, a plurality (three in this embodiment 1) of flat wound electrode bodies 30 (hereinafter also simply referred to as "electrode bodies 30") housed in the case 10, a positive electrode terminal 50 fixed to the case 10 via a resin member 55, and a negative electrode terminal 60 fixed to the case 10 via a resin member 65, etc. The plurality of electrode bodies 30 are covered within the case 10 by a single insulating holder 5 made of insulating film and forming a cylindrical shape that extends in the battery width direction BH. An electrolyte 3 is also housed in the case 10, and this electrolyte 3 is impregnated into each electrode body 30.

[0014] Each electrode body 30 is formed by overlapping a strip-shaped positive electrode plate 41 and a strip-shaped negative electrode plate 44 with a pair of strip-shaped porous resin membrane separators 47, winding them cylindrically around a winding axis 30x, and then pressing them into a flattened shape. The electrode body 30 has an oval cross-section perpendicular to the axial direction EH along the winding axis 30x, and has an elongated cylindrical shape, comprising a rectangular parallelepiped electrode body portion 31 and a pair of semi-cylindrical R portions (one R portion 32 and the other R portion 33) connected to the electrode body portion 31.

[0015] Of these, the electrode body portion 31 is a portion in which the positive electrode plate 41, the negative electrode plate 44, and the separator 47 are stacked in a flat plate shape in the thickness direction. One side R portion 32 is located on one side DH1 (in this embodiment, coinciding with the upper side AH1 of the battery height direction AH) of the electrode body width direction DH which is perpendicular to the axial direction EH and the electrode body thickness direction FH, respectively, and the other side R portion 33 is located on the other side DH2 (in this embodiment, coinciding with the lower side AH2 of the battery height direction AH) of the electrode body width direction DH which is opposite to the one side DH1. One side R portion 32 and the other side R portion 33 are portions in which the positive electrode plate 41, the negative electrode plate 44, and the separator 47 overlap while bending in a semi-cylindrical shape, respectively. Furthermore, the electrode body 30 has a positive electrode current collector 30c, described later, at one end EH1 in the axial direction EH (which in this embodiment coincides with one end BH1 in the battery width direction BH), and a negative electrode current collector 30d, described later, at the other end EH2 in the axial direction EH (which in this embodiment coincides with the other end BH2 in the battery width direction BH).

[0016] The positive electrode plate 41 has a positive electrode current collector foil made of a strip of aluminum foil, and a positive electrode active material layer containing positive electrode active material particles capable of intercalating and releasing lithium ions is formed on both main surfaces of this positive electrode current collector foil. The positive electrode plate 41 has a plurality of positive electrode extensions 41t that extend from the center of the electrode body width direction DH to one side EH1 in the axial direction EH. In each positive electrode extension 41t, there is no positive electrode active material layer on the positive electrode current collector foil, and the positive electrode current collector foil is exposed. These positive electrode extensions 41t overlap in the thickness direction to form a positive electrode current collector portion 30c. This positive electrode current collector portion 30c is joined to a rectangular plate-shaped positive electrode current collector member 53 (ultrasonic welding in this embodiment), and the positive electrode current collector member 53 is further joined to a positive electrode terminal 50 (laser welding in this embodiment).

[0017] The negative electrode plate 44 has a negative electrode current collector foil made of a strip of copper foil, and a negative electrode active material layer containing negative electrode active material particles capable of intercalating and releasing lithium ions is formed in a strip shape on both main surfaces of this negative electrode current collector foil. The negative electrode plate 44 has a plurality of negative electrode extensions 44t that extend from the center in the electrode width direction DH to the other side EH2 in the axial direction EH. In each of the negative electrode extensions 44t, there is no negative electrode active material layer on the negative electrode current collector foil, and the negative electrode current collector foil is exposed. These negative electrode extensions 44t overlap in the thickness direction to form a negative electrode current collector portion 30d. This negative electrode current collector portion 30d is joined (ultrasonic welding in this embodiment) to a rectangular plate-shaped negative electrode current collector member 63, and the negative electrode current collector member 63 is further joined (laser welding in this embodiment) to a negative electrode terminal 60.

[0018] Multiple electrode bodies 30 are arranged so that their winding axes 30x are parallel to each other and they overlap in the electrode body thickness direction FH, and these electrode bodies 30 are housed in the case 10 via an insulating holder 5. In this embodiment 1, the electrode body width direction DH of each electrode body 30 coincides with the battery height direction AH, the axial direction EH of each electrode body 30 coincides with the battery width direction BH, and the electrode body thickness direction FH of each electrode body 30 coincides with the battery thickness direction GH.

[0019] Next, the case 10 will be described. The case 10 is composed of six case walls, namely a first case wall 11, a second case wall 12, a third case wall 13, a fourth case wall 14, a fifth case wall 15, and a sixth case wall 16. In the first embodiment, the third case wall 13 is a top wall of the case 10, the fourth case wall 14 is a bottom wall of the case 10, and the remaining first case wall 11, second case wall 12, fifth case wall 15, and sixth case wall 16 are each side walls of the case 10.

[0020] The first case wall 11 and the second case wall 12 are each in the shape of a flat plate. The first case wall 11 and the second case wall 12 face each other, the first case wall 11 is located on one side CH1 in the battery thickness direction CH, and the second case wall 12 is located on the other side CH2 in the battery thickness direction CH. The first case wall 11 is orthogonal to the electrode body thickness direction FH, and is in surface contact with a plurality of stacked electrode bodies 30 (specifically, electrode main bodies 31) indirectly from one side FH1 in the electrode body thickness direction FH via an insulating holder 5 (the flat inner wall surface of the first case wall 11 and the flat surface of the electrode main body 31 are in surface-to-surface contact). Therefore, heat conduction from the plurality of stacked electrode bodies 30 to the first case wall 11 is enhanced.

[0021] The second case wall 12 is orthogonal to the electrode body thickness direction FH, and is in surface contact with a plurality of stacked electrode bodies 30 (specifically, electrode main bodies 31) indirectly from the other side FH2 in the electrode body thickness direction FH via an insulating holder 5 (the flat inner wall surface of the second case wall 12 and the flat surface of the electrode main body 31 are in surface-to-surface contact). Therefore, heat conduction from the plurality of stacked electrode bodies 30 to the second case wall 12 is enhanced.

[0022] The third case wall 13 and the fourth case wall 14 each connect between the first case wall 11 and the second case wall 12 and face each other. The third case wall 13 is located on the upper side AH1 in the battery height direction AH (one side DH1 in the electrode body width direction DH), and the fourth case wall 14 is located on the lower side AH2 in the battery height direction AH (the other side DH2 in the electrode body width direction DH). The third case wall portion 13 has a shape in which the same number of one-side semicylindrical inner wall surfaces 13n as the number of electrode assemblies 30 (three in the first embodiment) are arranged in the electrode assembly thickness direction FH. Each one-side semicylindrical inner wall surface 13n is a semicylindrical surface protruding toward one side DH1 in the electrode assembly width direction DH along the semicylindrical outer peripheral surface 32r of the one-side rounded portion 32. In the first embodiment, since the thickness of the third case wall portion 13 is substantially constant, the third case wall portion 13 has a shape (substantially corrugated shape) in which semicylindrical wall portions are arranged in the electrode assembly thickness direction FH. Each one-side semicylindrical inner wall surface 13n of the third case wall portion 13 is in surface contact with the one-side rounded portion 32 of each of the plurality of electrode assemblies 30 indirectly via the respective insulating holder 5 (the one-side semicylindrical inner wall surface 13n and the outer peripheral surface 32r are in contact with each other as surfaces). Accordingly, heat conduction from each one-side rounded portion 32 to the third case wall portion 13 is enhanced.

[0023] The fourth case wall portion 14 has a shape in which the same number of other-side semicylindrical inner wall surfaces 14n as the number of electrode assemblies 30 (three in the first embodiment) are arranged in the electrode assembly thickness direction FH. Each other-side semicylindrical inner wall surface 14n is a semicylindrical surface protruding toward the other side DH2 in the electrode assembly width direction DH along the semicylindrical outer peripheral surface 33r of the other-side rounded portion 33. In the first embodiment, since the thickness of the fourth case wall portion 14 is substantially constant, the fourth case wall portion 14 has a shape (substantially corrugated shape) in which semicylindrical wall portions are arranged in the electrode assembly thickness direction FH. Each other-side semicylindrical inner wall surface 14n of the fourth case wall portion 14 is in surface contact with the other-side rounded portion 33 of each of the plurality of electrode assemblies 30 indirectly via the respective insulating holder 5 (the other-side semicylindrical inner wall surface 14n and the outer peripheral surface 33r are in contact with each other as surfaces). Accordingly, heat conduction from each other-side rounded portion 33 to the fourth case wall portion 14 is enhanced.

[0024] The fifth case wall portion 15 and the sixth case wall portion 16 are both flat. The fifth case wall portion 15 and the sixth case wall portion 16 are perpendicular to the axial direction EH of each electrode body 30 and face each other, with the fifth case wall portion 15 located on one side BH1 in the battery width direction BH and the sixth case wall portion 16 located on the other side BH2 in the battery width direction BH. These fifth case wall portion 15 and the sixth case wall portion 16 are spaced apart from the electrode body portion 31, one side R portion 32 and the other side R portion 33 of each electrode body 30.

[0025] A positive electrode terminal 50 made of aluminum is hermetically fixed to the fifth case wall 15. Specifically, the fifth case wall 15 is provided with an insertion hole 15h, and the positive electrode terminal 50 is inserted into this insertion hole 15h and extends from the inside to the outside of the case 10. The positive electrode terminal 50 is fixed to the fifth case wall 15 in an insulated state via an insert-molded resin member 55. As described above, the positive electrode terminal 50 is electrically connected to the positive electrode current collector 30c of the electrode body 30 via a positive electrode current collector member 53 within the case 10. The fifth case wall 15 is also provided with a safety valve 15v that breaks and opens when the internal pressure of the case 10 exceeds the opening pressure. Furthermore, the fifth case wall 15 is provided with an injection hole 10k, which is hermetically sealed with a disc-shaped sealing member 18.

[0026] A negative electrode terminal 60 made of copper is hermetically fixed to the sixth case wall 16. Specifically, the sixth case wall 16 is provided with an insertion hole 16h, and the negative electrode terminal 60 is inserted into this insertion hole 16h and extends from the inside to the outside of the case 10. The negative electrode terminal 60 is fixed to the sixth case wall 16 in an insulated state via an insert-molded resin member 65. As described above, the negative electrode terminal 60 is electrically connected to the negative electrode current collector 30d of the electrode body 30 via a negative electrode current collector member 63 within the case 10. Also, similar to the fifth case wall 15, a safety valve 16v is provided in the sixth case wall 16.

[0027] The above-described case 10 is constructed by joining a cylindrical case body 21 with a pair of plate-shaped lids (first lid 22 and second lid 23). In this embodiment 1, the case body 21 is made of a single component, specifically, a single extruded material formed by extrusion molding. The first lid 22 and the second lid 23 are also each made of a single component. The case body 21 extends in the battery width direction BH, has a first opening 21c at one end of BH1 in the battery width direction BH, and has a second opening 21d at the other end of BH2 in the battery width direction BH. This case body 21 integrally includes the aforementioned first case wall 11, second case wall 12, third case wall 13, and fourth case wall 14 of the case 10, and houses a plurality of electrode bodies 30 inside the case body 21.

[0028] The first cover 22 forms the fifth case wall 15 of the case 10. This first cover 22 hermetically seals the first opening 21c of the case body 21. Specifically, with the peripheral edge 22f of the first cover 22 placed over the first opening 21c of the case body 21, a laser beam is irradiated all around the first opening 21c and the peripheral edge 22f from the radially outer side of the case body 21 (in a direction perpendicular to the battery width direction BH), thereby hermetically welding the first opening 21c and the peripheral edge 22f all around. The second lid 23 forms the sixth case wall 16 of the case 10. This second lid 23 airtightly closes the second opening 21d of the case body 21. Specifically, the second opening 21d of the case body 21 and the peripheral edge 23f of the second lid 23 are laser-welded airtightly around their entire circumference, similar to the first opening 21c of the case body 21 and the peripheral edge 22f of the first lid 22 described above.

[0029] In the battery 1 of this embodiment 1, the third case wall 13 of the case 10 has a shape in which multiple semi-cylindrical inner wall surfaces 13n, each forming a semi-cylindrical surface, are arranged in a row, as described above. Furthermore, the first case wall 11 and the second case wall 12 of the case 10 are not only in contact with the multiple stacked electrode bodies 30, but the third case wall 13 of the case 10 is also in contact with the one-sided R portion 32 of each of the multiple electrode bodies 30. As a result, not only is the heat conduction from the multiple electrode bodies 30 to the first case wall 11 and the second case wall 12 of the case 10 high, but the heat conduction from the one-sided R portion 32 of the multiple electrode bodies 30 to the third case wall 13 of the case 10 can also be increased. Therefore, the battery 1 of this embodiment 1 can be cooled more appropriately than a battery in which the third case wall of the case is flat and there is a space between the third case wall and the one-sided R portion of the multiple electrode bodies. Furthermore, since the third case wall portion 13 of case 10 has a shape in which multiple one-sided semi-cylindrical inner wall surfaces 13n are arranged side by side, the rigidity of case 10 can be increased.

[0030] Furthermore, in battery 1, the fourth case wall 14 of case 10 has a shape in which multiple semi-cylindrical inner wall surfaces 14n on the other side, which form a semi-cylindrical surface, are arranged side by side, as described above. This fourth case wall 14 is in contact with the other side R portion 33 of each of the multiple electrode bodies 30. This further increases the heat conduction from the other side R portion 33 of the multiple electrode bodies 30 to the fourth case wall 14 of case 10. Also, since the fourth case wall 14 of case 10 has a shape in which multiple other side semi-cylindrical inner wall surfaces 14n are arranged side by side, the rigidity of case 10 can be further increased.

[0031] Furthermore, in battery 1, the case body 21, including the first case wall 11, second case wall 12, third case wall 13, and fourth case wall 14, is made of a cylindrical extruded material. Therefore, it is easy to make the third case wall 13 a shape with multiple semi-cylindrical inner wall surfaces 13n on one side and the fourth case wall 14 a shape with multiple semi-cylindrical inner wall surfaces 14n on the other side. For this reason, even though the third case wall 13 and the fourth case wall 14 have complex shapes, an inexpensive battery 1 can be made.

[0032] (Embodiment 2) Next, a second embodiment will be described (see Figure 4). Note that explanations of parts similar to those in Embodiment 1 will be omitted or simplified. The battery (energy storage device) 100 of this second embodiment differs in the shape of the case 110 from that of the battery 1 in Embodiment 1. Specifically, in the case 10 according to Embodiment 1, the third case wall portion 13 is shaped as having multiple semi-cylindrical inner wall surfaces 13n on one side that form a semi-cylindrical surface, and the fourth case wall portion 14 is shaped as having multiple semi-cylindrical inner wall surfaces 14n on the other side that form a semi-cylindrical surface. In contrast, in the case 110 according to this second embodiment, only the third case wall portion 13 has a shape in which multiple semi-cylindrical inner wall surfaces 13n forming a semi-cylindrical surface are arranged side by side, while the fourth case wall portion 114 is flat. The other case wall portions (first case wall portion 11, second case wall portion 12, fifth case wall portion 15, and sixth case wall portion 16) are the same as in the first embodiment.

[0033] In the battery 100 of this second embodiment, the third case wall 13 of the case 10 is shaped in such a way that multiple semi-cylindrical inner wall surfaces 13n, each forming a semi-cylindrical surface, are arranged in a row, and these surfaces are in contact with the semi-cylindrical outer surface 32r of the one-sided R portion 32 of the multiple electrode bodies 30. This allows for high heat conduction from the one-sided R portion 32 of the multiple electrode bodies 30 to the third case wall 13 of the case 10. Furthermore, in the battery 100, the case body 121, including the first case wall 11, the second case wall 12, the third case wall 13, and the fourth case wall 114, is made of a cylindrical extruded material. Therefore, it is easy to make the third case wall 13 a shape in which multiple one-sided semi-cylindrical inner wall surfaces 13n are arranged, and despite the complex shape of the third case wall 13, an inexpensive battery 100 can be made. Other parts that are the same as in Embodiment 1 have the same effects as in Embodiment 1.

[0034] Although the present invention has been described above in reference to Embodiments 1 and 2, it goes without saying that the present invention is not limited to Embodiments 1 and 2, and can be applied with appropriate modifications without departing from the spirit of the invention. For example, in Embodiments 1 and 2, lithium-ion secondary batteries were used as examples of energy storage devices, but the device is not limited to these. Other energy storage devices include, for example, secondary batteries such as sodium-ion secondary batteries and calcium-ion secondary batteries, and capacitors such as lithium-ion capacitors.

[0035] Furthermore, while embodiments 1 and 2 illustrate a battery 1,100 in which the cases 10 and 110 and the electrode body 30 are indirectly in contact via an insulating holder 5, the invention is not limited to this. The case and the electrode body may be in direct contact. For example, the first case wall and the second case wall may be in direct contact with the electrode body portion of the electrode body, the third case wall may be in direct contact with one side R portion of the electrode body, and the fourth case wall may be in direct contact with the other side R portion of the electrode body. [Explanation of Symbols]

[0036] 1,100 Batteries (energy storage devices) 10,110 cases 11. Case 1 Wall Section 12. Case 2 Wall Section 13. Third case wall section 13n One side semi-cylindrical inner wall surface 14,114 Case 4 Wall Section 14n Other side semi-cylindrical inner wall surface 15. Wall section of case 5 16. Wall section of case 6 21,121 Case body 21c 1st opening 21d 2nd opening 22 First Lid 23. Second Lid 30 Electrode body (flat wound electrode body) 30x winding axis 31 Electrode body 32 One side R section 32r (outer surface of one side R portion) 33 Other side R section 33r (outer surface of the other R portion) 41 Positive electrode plate (electrode plate) 44 Negative electrode plate (electrode plate) DH electrode body width direction EH Axial direction FH electrode thickness direction FH1 (one side in the electrode thickness direction) FH2 (other side in the electrode thickness direction)

Claims

1. A metal case, The present invention comprises a plurality of flat wound electrode bodies, each of which has a winding axis parallel to the others and is housed in the case in an overlapping state in the thickness direction of the electrode bodies. It is an energy storage device, The aforementioned case is, A first case wall portion is provided, which is a flat plate-shaped portion perpendicular to the thickness direction of the electrode body and directly or indirectly contacts a plurality of stacked flat wound electrode bodies from one side in the thickness direction of the electrode body, A second case wall portion is a flat plate-shaped portion perpendicular to the electrode thickness direction and facing the first case wall portion, which directly or indirectly contacts the stacked plurality of flat wound electrode bodies from the opposite side in the electrode thickness direction to the one side, It has a third case wall portion that connects the first case wall portion and the second case wall portion and is located on one side in the electrode width direction perpendicular to the winding axis and the electrode thickness direction, The above third case wall section is, In the flat wound electrode body, a semi-cylindrical surface is formed along the outer circumferential surface of the semi-cylindrical one-side R portion located on one side in the electrode body width direction, which is convex to the one side in the electrode body width direction. The outer circumferential surface of the aforementioned one side R portion, which is in direct or indirect contact with the other side R portion. The same number of inner walls on one side of the flattened wound electrode body as the number of semi-cylindrical walls on the other side are arranged in the thickness direction of the electrode body. Energy storage device.

2. The energy storage device according to claim 1, The aforementioned case is, A fourth case wall portion is located between the first case wall portion and the second case wall portion, on the opposite side of the electrode body width direction from the one side, and facing the third case wall portion. The fourth case wall portion is, In the flat wound electrode body, a semi-cylindrical surface is formed along the outer circumferential surface of the semi-cylindrical other side R portion located on the other side in the electrode body width direction, which is convex toward the other side in the electrode body width direction. The other side R portion is in direct or indirect contact with the outer circumferential surface. The other semi-cylindrical inner wall surface, which is the same number as the flattened wound electrode body, is arranged in the thickness direction of the electrode body. Energy storage device.

3. The energy storage device according to claim 1, The aforementioned case is, A cylindrical case body made of an extruded material, which integrally includes the first case wall, the second case wall, and the third case wall, The case body comprises a pair of lids that close a pair of openings located at both ends. Energy storage device.

4. The energy storage device according to claim 2, The aforementioned case is, A cylindrical case body made of an extruded material, which integrally includes the first case wall, the second case wall, the third case wall, and the fourth case wall, The case body comprises a pair of lids that close a pair of openings located at both ends. Energy storage device.

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