Energy storage devices

Abstract

To provide an energy storage device that easily maintains the sealing performance of the liquid injection hole. [Solution] The present invention provides an energy storage device comprising an electrode body, a battery case having an electrolyte injection hole 15, and a blind rivet 16 for sealing the electrolyte injection hole 15. The battery case has a raised portion 14s on the electrode body side and a recess 14r on the opposite side of the raised portion 14s at the periphery of the electrolyte injection hole 15, and the blind rivet 16 has an insertion portion 16a and a flange portion 16b, the flange portion 16b being housed in the recess 14r.

Description

Technical Field

[0001] The present invention relates to an electricity storage device.

Background Art

[0002] Conventionally, there has been known an electricity storage device including an electrode body, an electrolytic solution, a battery case that accommodates the electrode body and the electrolytic solution and has a liquid injection hole, and a sealing member that seals the liquid injection hole (for example, Patent Documents 1 and 2). Patent Document 1 discloses using a blind rivet as the sealing member. In the invention described in Patent Document 1, the inner surface side of the battery case is counterbored to provide a recess around the liquid injection hole, and at least a part of the expanded diameter portion of the blind rivet is disposed in the recess.

Prior Art Literature

Patent Literature

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problem to be Solved by the Invention

[0004] Incidentally, in energy storage devices, there is a demand to make the battery case thinner in order to improve energy density and other aspects. However, if the battery case is simply made thinner, for example, in a battery like the one in Patent Document 1, there is a concern that the sealing performance of the electrolyte injection holes will easily decrease. For example, if the thickness of the battery case is reduced, the rigidity may decrease near the electrolyte injection holes, especially in the areas where recesses have been created by counterboring. As a result, it is anticipated that the electrolyte injection holes may be more likely to open when a load is applied to the blind rivets or when the pressure inside the battery case increases. Also, if rigidity is to be maintained in the areas where recesses have been created, the heads of the blind rivets may be more likely to protrude from the battery case. As a result, it is anticipated that the protruding parts may interfere with other components, making it easier for loads to be placed on the blind rivets.

[0005] This invention has been made in view of the above circumstances, and aims to provide an energy storage device in which the sealing performance of the liquid injection hole can be easily maintained even when the battery case is made thinner. [Means for solving the problem]

[0006] The present invention provides an energy storage device comprising an electrode body, an electrolyte, a battery case containing the electrode body and the electrolyte and having an electrolyte injection hole, and a blind rivet for sealing the electrolyte injection hole. The battery case has a raised portion on the periphery of the electrolyte injection hole that is raised toward the electrode body, and a recess provided on the opposite side of the raised portion that is recessed toward the electrode body at the periphery of the electrolyte injection hole. The blind rivet has an insertion portion inserted through the electrolyte injection hole and a flange portion extending outward from one end of the insertion portion to the battery case, the flange portion being housed in the recess of the battery case.

[0007] The above configuration allows for a relative increase in rigidity near the liquid injection hole. Furthermore, it suppresses interference between blind rivets and other components. Therefore, for example, even if the battery case is made thinner, it becomes easier to maintain the sealing performance of the case. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a schematic perspective view showing an energy storage device according to one embodiment. [Figure 2] Figure 2 is a schematic longitudinal cross-sectional view along the line II-II in Figure 1. [Figure 3] Figure 3 is a schematic, partially broken perspective view showing the vicinity of the injection hole in Figure 1. [Figure 4] Figure 4 is a schematic longitudinal cross-sectional view showing the vicinity of the injection port in Figure 2. [Figure 5] Figure 5 is a diagram corresponding to Figure 4, relating to the first modified example. [Modes for carrying out the invention]

[0009] Hereinafter, preferred embodiments of the energy storage devices disclosed herein will be described with reference to the drawings as appropriate. Matters other than those specifically mentioned herein that are necessary for carrying out the disclosed technology (for example, the general configuration and manufacturing process of energy storage devices that do not characterize the disclosed technology) can be understood as design matters of those skilled in the art based on the prior art. The disclosed technology can be carried out based on the contents disclosed herein and common technical knowledge in the art. In addition, in the following drawings, the same reference numerals are used to denote members and parts that perform the same function.

[0010] In this specification, "energy storage device" refers to any device that can be repeatedly charged and discharged by the movement of a charge carrier between a positive electrode and a negative electrode via an electrolyte. Energy storage devices are 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. Furthermore, in this specification, the notation "A~B" indicating a range shall encompass not only the meaning of "greater than A and less than or equal to B," but also the meanings of "greater than A" and "less than B."

[0011] Figure 1 is a perspective view of an energy storage device 100 according to one embodiment. Figure 2 is a schematic longitudinal cross-sectional view of the energy storage device 100 in Figure 1 along line II-II, showing the internal structure of the energy storage device 100. In the following description, the symbols L, R, F, Rr, U, and D in the drawings represent left, right, front, back, top, and bottom, respectively, and the symbols X, Y, and Z in the drawings represent the short side direction, the long side direction perpendicular to the short side direction, and the height direction perpendicular to the short side direction and the long side direction of the energy storage device 100, respectively. However, these are merely directions for the convenience of explanation and do not limit the installation configuration of the energy storage device 100 in any way.

[0012] As shown in Figure 1, the energy storage device 100 has a hexahedron shape (more specifically, a rectangular parallelepiped shape). As shown in Figure 2, the energy storage device 100 comprises a battery case 10, an electrode body 20, and an electrolyte (not shown). The energy storage device 100 further comprises a positive electrode terminal 30 and a negative electrode terminal 40. The energy storage device 100 is a non-aqueous electrolyte secondary battery. Preferably, the energy storage device 100 is a lithium-ion secondary battery.

[0013] The battery case 10 is a housing that contains the electrode body 20 and the electrolyte. As shown in Figure 1, the battery case 10 has a flattened, bottomed rectangular parallelepiped (square) shape. The material of the battery case 10 can be the same as that used conventionally, and there are no particular restrictions. The battery case 10 is preferably made of metal, and more preferably of aluminum, aluminum alloy, iron, iron alloy (e.g., stainless steel). Stainless steel is particularly preferred. Stainless steel has a higher melting point and higher mechanical strength than, for example, aluminum or aluminum alloy. Therefore, by using stainless steel, even if the battery case 10 is made thin, it becomes less likely to deform or break. Thus, the effects of the technology disclosed herein can be exhibited more stably and at a higher level.

[0014] As shown in Figure 2, the battery case 10 of this embodiment includes a case body 12 having an opening 12h and a sealing plate 14 that seals the opening 12h. More specifically, the battery case 10 includes a case body 12 having openings 12h at both ends in the long side direction Y, and two sealing plates 14 that close the pair of openings 12h of the case body 12, respectively.

[0015] The case body 12 is a hollow rectangular tube. As shown in Figure 1, the case body 12 has a roughly rectangular bottom surface 12a (first surface) having a pair of long sides and a pair of short sides, a pair of long sides 12b (second surface) extending upward from the pair of long sides (edges) of the bottom surface 12a and facing each other, and an upper surface 12c (third surface) facing the bottom surface 12a. The long sides 12b have a larger area than the bottom surface 12a and the upper surface 12c. The upper surface 12c is roughly rectangular, similar to the bottom surface 12a. The upper surface 12c connects the upper ends of the pair of long sides 12b.

[0016] In this specification, "approximately rectangular" is a term that includes not only a perfect rectangle, but also shapes such as those where the corners connecting the long and short sides of a rectangle are rounded (R-shaped), or shapes with notches at the corners.

[0017] The case body 12 of this embodiment is formed by bending a single metal plate into a cylindrical shape and joining the joints (for example, by welding). The bottom surface 12a, the pair of long sides 12b, and the top surface 12c are each flat and have a substantially uniform thickness. As shown in Figure 1, a welded joint 12d is provided on the top surface 12c of the case body 12 where the ends of the metal plates are butted together. In the case body 12, the boundary portion (edge) between the bottom surface 12a and the long sides 12b, and the boundary portion (edge) between the long sides 12b and the top surface 12c are bent portions. As a result, even if the case body 12 is made thin, for example, the case body 12 is less likely to deform or break. Therefore, the effects of the technology disclosed herein can be exhibited more stably at a higher level.

[0018] The plate thickness T2 (average thickness of the metal plate, not shown) of the case main body 12 is not particularly limited because it may vary depending on the material and other factors, but from the viewpoint of improving mechanical strength, rigidity, durability, etc., it is preferably 0.1 mm or more, more preferably 0.2 mm or more, and still more preferably 0.3 mm or more. Further, from the viewpoint of improving the energy density of the electricity storage device 100, the plate thickness T2 of the case main body 12 is preferably 2 mm or less, more preferably 1 mm or less, and still more preferably 0.5 mm or less.

[0019] As shown in Figure 2, a gas discharge valve 13 is provided on the lower surface 12a of the case main body 12. The gas discharge valve 13 is configured to break when the pressure inside the battery case 10 reaches a predetermined value or higher, and discharge the gas inside the battery case 10 to the outside. Although the number of the gas discharge valves 13 is one in the present embodiment, it may be two or more in other embodiments. In addition, the position, area, shape, etc. of the gas discharge valve 13 can be changed as appropriate.

[0020] The sealing plate 14 is a substantially rectangular plate-shaped member that seals the opening 12h of the case main body 12. The area of the sealing plate 14 is smaller than that of the long side surface 12b in the present case. As will be described in detail later, the sealing plate 14 of the present embodiment is formed by subjecting a single metal plate to press working called drawing (including deep drawing). This makes it possible to improve processability and productivity. The sealing plate 14 has a substantially uniform plate thickness T4 (see Figure 4).

[0021] The plate thickness T4 of the sealing plate 14 is not particularly limited because it may vary depending on the material and other factors, but from the viewpoint of improving mechanical strength, rigidity, durability, etc., it is preferably 0.1 mm or more, more preferably 0.2 mm or more, and still more preferably 0.3 mm or more. Further, from the viewpoint of improving the energy density of the electricity storage device 100, the plate thickness T4 of the sealing plate 14 is preferably 2 mm or less, more preferably 1 mm or less, and still more preferably 0.6 mm or less.

[0022] As shown in Figure 2, the sealing plate 14 is fitted into the opening 12h of the case body 12. More specifically, in this embodiment, the sealing plate 14 is positioned to cover the end face of the case body 12, and a welded joint (not shown) is provided at the contact point between the case body 12 and the sealing plate 14. In some embodiments, the welded joint is preferably a laser weld formed by laser welding. The welded joint is provided in an annular shape along the periphery of the pair of openings 12h of the case body 12 (the outer peripheral edge of the sealing plate 14). The battery case 10 is integrated by welding the sealing plate 14 to the periphery of the pair of openings 12h of the case body 12. As a result, the openings 12h of the case body 12 are airtightly sealed.

[0023] As shown in Figure 2, one of the sealing plates 14 (the one on the right in Figure 2) has an electrolyte injection hole 15. The electrolyte injection hole 15 is for injecting electrolyte into the inside of the battery case 10 after the pair of sealing plates 14 have been assembled to the case body 12. Here, the electrolyte injection hole 15 is a through hole that penetrates the sealing plate 14 in the direction of its long side Y. That is, the direction of its long side Y is the axial direction A of the electrolyte injection hole 15 (see Figure 4). Here, the electrolyte injection hole 15 is formed in a substantially circular shape in plan view. After the electrolyte is injected, the electrolyte injection hole 15 is sealed with a blind rivet 16 as a sealing member. In some embodiments, it is preferable that the electrolyte injection hole 15 is provided in the sealing plate 14. However, in other embodiments, the electrolyte injection hole 15 may be provided in the case body 12.

[0024] In some embodiments, it is preferable that the plate thickness of a member provided with the liquid injection hole 15 is greater than the plate thickness of a member not provided with the liquid injection hole 15. In the present embodiment, it is preferable that the plate thickness T4 of the sealing plate 14 is greater than the plate thickness T2 of the case main body 12 (T2 < T4). This facilitates forming a welded joint with a deep welding depth (penetration) when forming the welded joint. Therefore, even if, for example, the battery case 10 is made thin as a whole, the welded joint is less likely to be damaged. The plate thickness T4 of the sealing plate 14 (the plate thickness of the member provided with the liquid injection hole 15) is preferably at least 1.5 times the plate thickness T2 of the case main body 12 (the plate thickness of the member not provided with the liquid injection hole 15), and more preferably at least 2 times.

[0025] FIG. 3 is a partially broken perspective view schematically showing the peripheral edge portion of the liquid injection hole 15 in FIG. 1. FIG. 4 is a vertical cross-sectional view schematically showing the peripheral edge portion of the liquid injection hole 15 in FIG. 2. Note that FIGS. 3 and 4 show the state when the sealing plate 14 is viewed from the front (a state obtained by rotating FIGS. 1 and 2 by 90°). As shown in FIGS. 3 and 4, the sealing plate 14 (battery case 10) of the present embodiment has a raised portion 14s and a recessed portion 14r on the peripheral edge of the liquid injection hole 15. The raised portion 14s and the recessed portion 14r are each provided along the outer edge of the liquid injection hole 15. The raised portion 14s and the recessed portion 14r are each provided so as to surround the periphery of the liquid injection hole 15. Here, the raised portion 14s and the recessed portion 14r are provided integrally with the sealing plate 14. Here, the raised portion 14s and the recessed portion 14r are provided integrally and inseparably.

[0026] The raised portion 14s and the recessed portion 14r can be formed by conventionally known methods, for example, press working (such as drawing), die casting, forging, casting, and the like. In the present embodiment, it is preferable that the raised portion 14s and the recessed portion 14r are deformed portions formed by bending and deforming the sealing plate 14 toward the electrode body 20 side. It is preferable that the raised portion 14s and the recessed portion 14r do not have a joint seam formed by bonding between the raised portion 14s and the recessed portion 14r and the base portion of the sealing plate 14 (a portion located outside the raised portion 14s and the recessed portion 14r in the radial direction of the liquid injection hole 15).

[0027] In some embodiments, the raised portion 14s and recessed portion 14r are preferably drawn portions formed by deep drawing. This improves ease of processing and productivity. Furthermore, in deep drawing, the thickness T4 of the sealing plate 14 can be kept substantially the same (processing errors etc. are permissible), and only the shape can be changed to form the raised portion 14s and recessed portion 14r. As a result, the increase in the weight and volume of the component itself can be suppressed, making it easier to stably achieve a high energy density.

[0028] The raised portion 14s is a part that is raised (protrudes) toward the electrode body 20 at the periphery of the liquid injection hole 15. The raised portion 14s is provided on the inner surface of the battery case 10 (the surface facing the electrode body 20). As shown in Figure 4, the raised portion 14s is provided here on the inner surface of the sealing plate 14. The raised portion 14s is a part of the sealing plate 14 that is partially raised (deformed) toward the electrode body 20 at the periphery of the liquid injection hole 15. In this case, the raised portion 14s is provided in a donut shape (specifically, an annular shape) so as to surround the liquid injection hole 15 in a plan view. In the sealing plate 14, the thickness of the part where the raised portion 14s is provided is approximately the same T4 as the base portion (the part outside the raised portion 14s in the radial direction of the liquid injection hole 15) (processing errors etc. are permissible).

[0029] By having a raised portion 14s around the periphery of the liquid injection hole 15, the rigidity near the liquid injection hole 15 can be relatively increased. As a result, even if a load is applied to the blind rivet 16 or the pressure inside the battery case 10 increases, the area near the liquid injection hole 15 is less likely to deform compared to, for example, if the periphery of the liquid injection hole 15 is counterbored, thereby improving deformation resistance. Therefore, even if, for example, the battery case 10 (in this case, the sealing plate 14) is made thinner, leakage at the liquid injection hole 15 becomes less likely. In other words, it becomes easier to maintain the sealing performance of the battery case 10. Ultimately, this can improve the reliability of the energy storage device 100.

[0030] The protruding length Ts of the raised portion 14s toward the electrode assembly 20 side (the maximum length in the long-side direction Y in FIG. 4, which is the vertical length protruding from the inner surface 14a of the sealing plate 14 herein) may vary depending on, for example, the size of the blind rivet 16 (the maximum length in the axial direction A), the plate thickness T4 of the sealing plate 14, etc., and is not particularly limited; however, it is preferably 0.5 to 4 mm, more preferably 1 to 3 mm, and even more preferably 1 to 2 mm. In one example, the protruding length Ts of the raised portion 14s is 1.5 mm. The protruding length Ts of the raised portion 14s is preferably larger than the plate thickness T4 of the sealing plate 14 (the plate thickness of the member provided with the liquid injection hole 15) (T4<Ts). The protruding length Ts of the raised portion 14s is preferably 1.5 times or more the plate thickness T4 of the sealing plate 14, and more preferably 2 times or more (for example, 2 to 5 times).

[0031] The recessed portion 14r is a portion recessed toward the electrode assembly 20 side at the peripheral edge of the liquid injection hole 15. The recessed portion 14r is provided on the opposite side of the raised portion 14s, that is, on the outer surface side of the battery case 10. As shown in FIG. 4, the recessed portion 14r is provided on the outer surface side of the sealing plate 14 herein. As can be seen from FIG. 3, the recessed portion 14r is provided in a donut shape (specifically, an annular shape) so as to surround the liquid injection hole 15 in a plan view herein. The recessed portion 14r overlaps the raised portion 14s in a plan view.

[0032] The recessed portion 14r of the present embodiment is configured to be able to accommodate the blind rivet 16. That is, as can be seen from FIGS. 3 and 4, the outer shape of the recessed portion 14r is larger than the outer shape of the blind rivet 16 (specifically, the outer shape of a flange portion 16b described later). In addition, as shown in FIG. 4, the depth Td of the recessed portion 14r (the maximum depth in the long-side direction Y in FIG. 4, which is the average length recessed from the outer surface 14b of the sealing plate 14 herein) is larger than the length of a portion of the blind rivet 16 that protrudes from the battery case 10.

[0033] The depth Td of the recess 14r may vary depending on, for example, the size of the blind rivet 16 (the maximum length in the axial direction A) and the plate thickness T4 of the sealing plate 14, and thus is not particularly limited. However, it is preferably 0.5 to 4 mm, more preferably 1 to 3 mm, and even more preferably 1 to 2 mm. In one example, the depth Td of the recess 14r is 1.5 mm. In some embodiments, the depth Td of the recess 14r is preferably larger than the plate thickness T4 of the sealing plate 14 (the thickness of the battery case 10 at the portion where the recess 14r is provided) (T4 < Td). This makes it easy to accommodate, in the recess 14r, the portion of the blind rivet 16 protruding from the battery case 10 even when the battery case 10 (here, the sealing plate 14) is thin. The depth Td of the recess 14r is preferably 1.5 times or more the plate thickness T4 of the sealing plate 14 (the thickness of the battery case 10 at the portion where the recess 14r is provided), and more preferably 2 times or more (for example, 2 to 5 times).

[0034] As shown in FIG. 4, the recess 14r includes: a first inclined portion SP1 inclined toward the liquid injection hole 15; and a second inclined portion SP2 provided on an outer edge side of the first inclined portion SP1 in the radial direction of the liquid injection hole 15 (the height direction Z in FIG. 4), and inclined toward the liquid injection hole 15 at an inclination angle different from that of the first inclined portion SP1. The recess 14r of the present embodiment further includes a first flat portion FP1 and a second inclined portion SP2. Specifically, the recess 14r of the present embodiment is configured by continuously connecting, from the side closer to the liquid injection hole 15, the first flat portion FP1, the first inclined portion SP1, the second flat portion FP2, and the second inclined portion SP2. However, the recess 14r of the present embodiment is merely an example. As described also in a first modified example mentioned later, in other embodiments, the recess 14r may not include the first flat portion FP1 and / or the second inclined portion SP2.

[0035] The first flat portion FP1 is provided along the periphery of the liquid injection hole 15, and is a portion spreading in the radial direction of the liquid injection hole 15 (the height direction Z in FIG. 4). In the radial direction of the liquid injection hole 15, the first flat portion FP1 is provided closer to the inner circumferential side (the side closer to the liquid injection hole 15) than the first inclined portion SP1, the second flat portion FP2, and the second inclined portion SP2. The first flat portion FP1 extends substantially parallel to the inner surface 14a of the sealing plate 14. As can be seen from FIG. 3, the first flat portion FP1 is provided herein in a donut shape (specifically, an annular shape) so as to surround the liquid injection hole 15 in a plan view.

[0036] The first inclined portion SP1 is provided along the outer edge of the first flat portion FP1. In the radial direction of the liquid injection hole 15 (the height direction Z in FIG. 4), the first inclined portion SP1 is provided closer to the inner circumferential side (the side closer to the liquid injection hole 15) than the second flat portion FP2 and the second inclined portion SP2. The first inclined portion SP1 is provided between the first flat portion FP1 and the second flat portion FP2. The first inclined portion SP1 is inclined toward the liquid injection hole 15 from the end portion of the second flat portion FP2 on the liquid injection hole 15 side. The first inclined portion SP1 is inclined at an inclination angle θ1 (see FIG. 4) toward the first flat portion FP1 from the outer edge side of the sealing plate 14. The inclination angle θ1 is typically 90° or less, is preferably an acute angle (0°<θ1<90°), and is more preferably 45° or less (for example, 5 to 30°).

[0037] In the axial direction A of the liquid injection hole 15, the vertical height H1 of the first inclined portion SP1 (the average length in the long side direction Y in FIG. 4) is preferably smaller than the plate thickness T4 of the sealing plate 14 (the thickness of the battery case 10 at the portion where the recess 14r is provided) (H1<T4). This makes it easy to accommodate the portion of the blind rivet 16 protruding from the battery case 10 in the recess 14r. In one example, the vertical height H1 of the first inclined portion SP1 is 0.5 mm.

[0038] As can be seen from Figure 3, the first inclined portion SP1 is provided in a donut shape (specifically, annular) so as to surround the first flat portion FP1 in a plan view. In some embodiments, it is preferable that the outer shape of the first inclined portion SP1 is larger than the outer shape of the flange portion 16b of the blind rivet 16 (the portion located outside the battery case 10), which will be described later. In this embodiment, as shown in Figure 4, it is preferable that the outer diameter D1 of the first inclined portion SP1 is larger than the outer diameter Db of the flange portion 16b of the blind rivet 16. It is preferable that the outer diameter D1 of the first inclined portion SP1 is 0.5 mm or more larger than the outer diameter Db of the flange portion 16b, and more preferably 1 mm or more larger. In one example, the outer diameter D1 of the first inclined portion SP1 is 7.5 mm. On the outer surface 14b of the sealing plate 14, a resin sealing member 18 (e.g., a sealing washer) is arranged on the surfaces of the first flat portion FP1 and the first inclined portion SP1.

[0039] The second flat portion FP2 is the portion that extends radially (height direction Z in Figure 4) of the liquid injection hole 15 between the first inclined portion SP1 and the second inclined portion SP2. In the radial direction of the liquid injection hole 15, the second flat portion FP2 is located on the inner circumference side (closer to the liquid injection hole 15) than the second inclined portion SP2. The second flat portion FP2 is located on the outer circumference side (farther from the liquid injection hole 15) than the first flat portion FP1. The second flat portion FP2 extends approximately parallel to the inner surface 14a of the sealing plate 14. As can be seen from Figure 3, the second flat portion FP2 is located here in a donut shape (specifically, annular) so as to surround the first inclined portion SP1 in a plan view.

[0040] The second inclined portion SP2 is provided along the outer edge of the second flat portion FP2. In the radial direction of the liquid injection hole 15 (height direction Z in Figure 4), the second inclined portion SP2 is provided on the outer circumference side (the side away from the liquid injection hole 15) than the first inclined portion SP1. The first inclined portion SP1 is provided between the base portion of the sealing plate 14 and the second flat portion FP2. The second inclined portion SP2 is inclined from the base portion of the sealing plate 14 toward the liquid injection hole 15. The second inclined portion SP2 is inclined from the outer edge side of the sealing plate 14 toward the second flat portion FP2 at an inclination angle θ2 (see Figure 4).

[0041] In the present embodiment, the inclination angle θ2 is different from the inclination angle θ1 of the first inclined portion SP1. The inclination angle θ2 is typically 90° or less, is preferably an acute angle (0° < θ2 < 90°), and more preferably 60° or less (for example, 45 to 60°). In some embodiments, the inclination angle θ2 is preferably larger than the inclination angle θ1. That is, it is preferable that the second inclined portion SP2 has a steeper gradient than the first inclined portion SP1. This makes it easy to keep the recess 14r relatively small. However, in other embodiments, the inclination angle θ2 may be the same as the inclination angle θ1, or may be smaller than the inclination angle θ1.

[0042] In the axial direction A of the electrolyte injection hole 15, the vertical height H2 of the second inclined portion SP2 (the average length in the long-side direction Y in FIG. 4) is preferably larger than the vertical height H1 of the first inclined portion SP1 (H1 < H2). It is preferably larger than the plate thickness T4 of the sealing plate 14 (the thickness of the battery case 10 at the portion where the recess 14r is provided) (T4 < H2). This makes it easy to accommodate the portion of the blind rivet 16 protruding from the battery case 10 in the recess 14r. For example, the vertical height H2 of the second inclined portion SP2 is 1 mm. As can be seen from FIG. 3, the second inclined portion SP2 is provided here in a donut shape (specifically, an annular shape) so as to surround the second flat portion FP2 in a plan view.

[0043] As shown in FIGS. 1 to 4, the electrolyte injection hole 15 is sealed with a blind rivet 16. The blind rivet 16 is typically made of metal. As shown in FIG. 4, the blind rivet 16 of the present embodiment includes an insertion portion 16a, a flange portion 16b, and a diameter-expanded portion 16c. The blind rivet 16 is caulked and fixed to the sealing plate 14 (specifically, the first flat portion FP1 herein) by the flange portion 16b and the diameter-expanded portion 16c.

[0044] The insertion portion 16a is a portion inserted into the liquid injection hole 15. As shown in FIG. 4, the insertion portion 16a extends along the axial direction A of the liquid injection hole 15 (the long-side direction Y in FIG. 4). As can be seen from FIG. 3, the insertion portion 16a is a hollow cylindrical column here. The outer shape of the insertion portion 16a is smaller than that of the liquid injection hole 15. Here, the insertion portion 16a is donut-shaped (specifically, annular) in a plan view. The outer diameter Da of the insertion portion 16a (see FIG. 4) is 3.3 mm in one example.

[0045] The flange portion 16b is a portion extending from one end of the insertion portion 16a (the upper end in FIG. 4) toward the outside of the battery case 10 (the upper side in FIG. 4, the direction away from the sealing plate 14). The flange portion 16b protrudes from the liquid injection hole 15 to the outside of the battery case 10. As can be seen from FIG. 3, the flange portion 16b is substantially disk-shaped in a plan view here. The outer shape of the flange portion 16b is larger than that of the liquid injection hole 15. The outer shape of the flange portion 16b is larger than that of the insertion portion 16a. Here, the flange portion 16b is substantially circular in a plan view. The outer diameter Db of the flange portion 16b (see FIG. 4) is larger than the outer diameter Da of the insertion portion 16a (Da<Db). Here, the outer diameter Db of the flange portion 16b is larger than the outer diameter Dc of the diameter-expanded portion 16c (Dc<Db). The outer diameter Db of the flange portion 16b is 6 mm in one example. However, in other embodiments, the flange portion 16b may have a shape other than a circular shape.

[0046] In the present embodiment, the flange portion 16b is accommodated in the recess 14r of the sealing plate 14 (the battery case 10). The flange portion 16b does not protrude from the recess 14r. As shown in FIG. 4, the outer diameter Db of the flange portion 16b is smaller than the outer diameter of the recess 14r of the sealing plate 14. Here, the outer diameter Db of the flange portion 16b is smaller than the outer diameter D1 of the first inclined portion SP1 (Db<D1). Further, in the axial direction A of the liquid injection hole 15 (the long-side direction Y in FIG. 4), the end portion 16t of the flange portion 16 on the side away from the battery case 10 (the upper end portion in FIG. 4, the end portion on the opposite side to the insertion portion 16a) is preferably located at a position overlapping the second inclined portion SP2, or is substantially flush with the surface of the base portion of the sealing plate 14 (manufacturing errors and the like are acceptable).

[0047] Since the flange 16b is housed in the recess 14r of the battery case 10, interference between the portion of the blind rivet 16 protruding from the battery case 10 and other members can be suppressed. This makes it difficult for a load to be applied to the blind rivet 16, and improves the deformation resistance in the vicinity of the liquid injection hole 15. Therefore, even when the battery case 10 (the sealing plate 14 in this case) is made thin, for example, leakage is less likely to occur at the liquid injection hole 15. In other words, it becomes easy to maintain the sealing performance of the battery case 10. Consequently, the reliability of the electricity storage device 100 can be improved.

[0048] In some embodiments, in the axial direction A of the liquid injection hole 15, it is preferable that the end of the flange 16b on the battery case 10 side (the lower end in FIG. 4, the end on the insertion portion 16a side) is located at a position overlapping the second inclined portion SP2 of the recess 14r. This makes it easy to house the flange 16b in the recess 14r.

[0049] The expanded diameter portion 16c is a portion extending from one end of the insertion portion 16a (the lower end in FIG. 4) toward the inside of the battery case 10 (the lower side in FIG. 4, the electrode body 20 side, the side opposite to the flange 16b). The outer shape of the expanded diameter portion 16c is larger than that of the liquid injection hole 15. The outer shape of the expanded diameter portion 16c is larger than that of the insertion portion 16a. As shown in FIG. 4, the expanded diameter portion 16c is in contact with the inner surface 14a of the sealing plate 14, more specifically, the first flat portion FP1. The outer diameter Dc of the expanded diameter portion 16c is larger than the outer diameter Da of the insertion portion 16a (Da<Dc). Here, the outer diameter Dc of the expanded diameter portion 16c is smaller than the outer diameter Db of the flange 16b (Dc<Db). In one example, the outer diameter Dc of the expanded diameter portion 16c is 4.7 mm.

[0050] As shown in Figure 2, the electrode body 20 is housed inside the battery case 10. Although not shown in the illustration, the electrode body 20 has a positive electrode and a negative electrode. The configuration of the electrode body 20 can be the same as conventional designs and is not particularly limited. The positive electrode typically has a positive electrode current collector and a positive electrode active material layer fixed to the positive electrode current collector. The negative electrode typically has a negative electrode current collector and a negative electrode active material layer fixed to the negative electrode current collector. The electrode body 20 may be housed inside the battery case 10 covered with a resin insulating sheet (electrode body holder). The electrode body 20 may be housed inside the battery case 10 integrated with a resin insulating member (e.g., a spacer).

[0051] The number of electrode bodies 20 housed inside the battery case 10 is not particularly limited; there may be one or two or more. In this embodiment, the electrode body 20 is a wound electrode body in which a strip-shaped positive electrode and a strip-shaped negative electrode are stacked with a strip-shaped separator in between, and wound in the longitudinal direction around a winding axis. In this embodiment, the electrode body 20 is arranged inside the battery case 10 in an orientation in which the winding axis is substantially parallel to the long side direction Y. However, in other embodiments, the electrode body 20 may be a laminated electrode body in which a plurality of rectangular positive electrodes and a plurality of rectangular negative electrodes are stacked in the short side direction X, for example, with insulation via a separator. Furthermore, each component constituting the electrode body 20 (positive electrode, negative electrode, separator, etc.) may be the same as those in a general energy storage device, and there are no particular restrictions.

[0052] As shown in Figure 2, the positive electrode of the electrode body 20 is provided with a positive electrode tab 23. The positive electrode tab 23 is part of the positive electrode current collector. The positive electrode tab 23 is convex and protrudes from the electrode body 20 toward the first sealing plate 14 (to the right in the long side direction Y in Figure 2). The positive electrode tab 23 is electrically connected to the positive electrode terminal 30 via the positive electrode current collector 32. On the other hand, the negative electrode of the electrode body 20 is provided with a negative electrode tab 24. The negative electrode tab 24 is part of the negative electrode current collector. The negative electrode tab 24 is convex and protrudes from the electrode body 20 toward the second sealing plate 14 (to the left in the long side direction Y in Figure 2). The negative electrode tab 24 is electrically connected to the negative electrode terminal 40 via the negative electrode current collector 42.

[0053] The electrolyte is housed inside the battery case 10 together with the electrode body 20. The electrolyte can be the same as conventional electrolytes and is not particularly limited. Typically, the electrolyte is a non-aqueous liquid electrolyte (non-aqueous electrolyte) containing a non-aqueous solvent and a supporting salt. The non-aqueous solvent includes, for example, carbonates such as ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC). The supporting salt (electrolyte salt) is, for example, a fluorine-containing lithium salt such as LiPF6 or a fluorine-containing sodium salt such as NaPF6.

[0054] The positive terminal 30 and the negative terminal 40 are fixed here to mutually opposing surfaces of the battery case 10 (specifically, a pair of sealing plates 14). More specifically, the positive terminal 30 is attached to the first sealing plate 14 (the sealing plate 14 on the right side in the long side direction Y in Figures 1 and 2). The positive terminal 30 is attached to the same surface as the blind rivets 16 of the battery case 10. The positive terminal 30 is preferably made of metal, and more preferably of aluminum or an aluminum alloy. As shown in Figure 2, the positive terminal 30 is electrically connected to the positive tab 23 inside the battery case 10 via the positive current collector 32.

[0055] The negative terminal 40 is attached to the second sealing plate 14 (the sealing plate 14 on the left side in the long side direction Y in Figures 1 and 2). The negative terminal 40 is preferably made of metal, and more preferably of copper or a copper alloy. As shown in Figure 2, the negative terminal 40 is electrically connected to the negative tab 24 inside the battery case 10 via the negative current collector 42. In this embodiment, the positive terminal 30 and the negative terminal 40 are provided on a pair of sealing plates 14, respectively, but in other embodiments, the positive terminal 30 and the negative terminal 40 may be provided on the same sealing plate 14, or they may be provided on the case body 12.

[0056] The energy storage device 100 described above can be manufactured by a manufacturing method that typically includes, for example, a battery case preparation step, an electrode housing step, a welding joining step, and a liquid injection step, in this order. In the battery case preparation step, a case body 12 and two sealing plates 14 are prepared. The case body 12 can be prepared, for example, by bending a single metal plate into a cylindrical shape and joining the joint (for example, by welding). The sealing plates 14 can be prepared, for example, by preparing a rectangular metal plate sized to fit the opening 12h of the case body 12, and then drawing this metal plate (more specifically, by a two-stage drawing process) to form a raised portion 14s and a recessed portion 14r on the periphery of the liquid injection hole 15. A positive electrode terminal 30 is attached to the first sealing plate 14, and a negative electrode terminal 40 is attached to the second sealing plate 14.

[0057] In the electrode housing process, the separately prepared electrode body 20 is housed in the case body 12. In one example, after housing the electrode body 20 in the case body 12, the positive electrode tab 23 of the electrode body 20 is joined to the positive electrode current collector 32 and electrically connected to the positive electrode terminal 30 provided on the first sealing plate 14. The negative electrode tab 24 of the electrode body 20 is joined to the negative electrode current collector 42 and electrically connected to the negative electrode terminal 40 provided on the second sealing plate 14.

[0058] In the welding process, the opening 12h of the case body 12 is sealed with a sealing plate 14 (sealing plate assembly). In one example, the outer edge of the sealing plate 14 is placed on the end face of the case body 12, and the sealing plate 14 is abutted against the opening 12h of the case body 12. In this state, the contact portion between the case body 12 and the sealing plate 14 is welded together. The welding method is not particularly limited, but examples include laser welding, electron beam welding, ultrasonic welding, and resistance welding. Laser welding is preferred among these. This forms a welded joint and seals the opening 12h of the case body 12.

[0059] In the electrolyte injection process, electrolyte is injected into the battery case 10. In this embodiment, the electrolyte is poured into the battery case 10 through the injection hole 15. After the electrolyte is injected, the injection hole 15 is sealed with a sealing member (blind rivet 16). Specifically, first prepare the blind rivet 16. The blind rivet 16 can be the same as those conventionally used, and there are no particular restrictions.

[0060] In one example, the blind rivet 16, in its pre-processing state (before sealing the injection hole 15), comprises a cylindrical sleeve that can be inserted into the injection hole 15, a flange-shaped part extending from one end of the sleeve with an outer diameter larger than the injection hole 15, a pocket portion that is part of the sleeve and is provided at the end opposite the flange, and a mandrel (shaft) provided inside the sleeve and the pocket portion. One end of the mandrel extends from the flange. The other end of the mandrel has a head formed thereon, which is larger in diameter than the other end. The head is located near the pocket portion.

[0061] Next, the prepared blind rivet 16 is inserted into the liquid injection hole 15 of the sealing plate 14. Specifically, the sleeve of the blind rivet 16 is inserted into the liquid injection hole 15 from the side of the bag portion. Then, while pressing the flange against the sealing plate 14, the portion of the mandrel extending from the flange is pulled upward with a tool or the like. As a result, the inside of the bag portion is plastically deformed, forming an enlarged diameter portion 16c at the lower end of the insertion portion 16a, and the portion of the mandrel extending from the flange is cut off and discharged. As a result, as shown in Figure 4, the blind rivet 16 is crimped and fixed to the periphery of the liquid injection hole 15, and the liquid injection hole 15 is sealed by the blind rivet 16. In this way, the battery case 10 is hermetically sealed and the energy storage device 100 is manufactured.

[0062] The energy storage device 100 can be used for various applications, but because the battery case 10 has a thin plate thickness and excellent energy density, it can be suitably used, for example, as a power source (driving power supply) for motors mounted on vehicles such as passenger cars and trucks. The type of vehicle is not particularly limited, but examples include plug-in hybrid electric vehicles (PHEVs), hybrid electric vehicles (HEVs), and battery electric vehicles (BEVs).

[0063] The embodiments of the technology disclosed herein have been described above. However, the above description is illustrative and does not limit the scope of the claims. The technologies described in the claims include various modifications and changes to the specific examples illustrated in the above description. For example, it is possible to replace some of the embodiments described above with other modifications, and it is also possible to add other modifications to the embodiments described above. In the following descriptions of modifications, explanations of matters common to the embodiments will be omitted or simplified.

[0064] <First Modified Example> Figure 5 is a diagram corresponding to Figure 4 relating to the first modified example. The sealing plate 114 shown in Figure 5 has a raised portion 114s and a recessed portion 114r on the periphery of the liquid injection hole 15. The protruding length Ts of the raised portion 114s is 1.25 mm in one example. The recessed portion 114r is composed of a first inclined portion SP11 and a second inclined portion SP12 extending from the first inclined portion SP11. Unlike the embodiment described above, the recessed portion 114r does not have a first flat portion and a second flat portion. The depth Td of the recessed portion 14r is 1.25 mm in one example. The outer diameter D1 of the first inclined portion SP11 is 7.5 mm here, as in the embodiment described above. The first inclined portion SP11 is provided along the periphery of the liquid injection hole 15. The first inclined portion SP11 is provided along the periphery of the liquid injection hole 15, which effectively increases the rigidity (especially the pulling stress) in the vicinity of the liquid injection hole 15.

[0065] <Second Modification> In the above-described embodiment, the case body 12 was rectangular in shape and had openings 12h at both ends in the long side direction Y. Also, there were two sealing plates 14. However, it is not limited to this. In the modified battery case, the case body 12 may be a bottomed rectangular (box-shaped) with an opening at only one end. In this case, there may be one sealing plate.

[0066] As described above, specific embodiments of the technology disclosed herein include those described in the following sections. Item 1: An energy storage device comprising an electrode body, an electrolyte, a battery case containing the electrode body and the electrolyte and having an electrolyte injection hole, and a blind rivet for sealing the electrolyte injection hole, wherein the battery case has a raised portion on the periphery of the electrolyte injection hole that is raised toward the electrode body, and a recess provided on the opposite side of the raised portion that is recessed toward the electrode body at the periphery of the electrolyte injection hole, and the blind rivet has a through portion inserted through the electrolyte injection hole and a flange portion extending outward from one end of the through portion to the battery case, the flange portion being housed in the recess of the battery case. Item 2: The energy storage device according to Item 1, wherein the raised portion and the recessed portion are drawn portions. Item 3: The energy storage device according to Item 2, wherein the depth of the recess is greater than the thickness of the battery case in the portion where the recess is provided. Item 4: The energy storage device according to item 1 or 2, wherein the recess comprises a first inclined portion inclined toward the liquid injection hole, and a second inclined portion provided on the outer edge side of the first inclined portion in the radial direction of the liquid injection hole, and inclined toward the liquid injection hole at a different inclination angle than the first inclined portion. Item 5: The energy storage device according to Item 4, wherein the second inclined section has a steeper gradient than the first inclined section. Item 6: The energy storage device according to item 4 or 5, wherein the outer shape of the first inclined portion is larger than the outer shape of the flange portion. Item 7: The energy storage device according to any one of items 4 to 6, wherein, in the axial direction of the liquid injection hole, the end of the flange portion on the battery case side is in a position that overlaps with the second inclined portion. Item 8: The energy storage device according to any one of items 4 to 7, wherein the recess is provided along the periphery of the liquid injection hole and further has a first flat portion extending radially from the liquid injection hole, and the first inclined portion is provided along the outer edge of the first flat portion. Item 9: The energy storage device according to any one of items 4 to 7, wherein the first inclined portion is provided along the outer edge of the liquid injection hole. Item 10: The battery case comprises a case body having an opening and a sealing plate that seals the opening, and the liquid injection hole is provided in the sealing plate, the energy storage device according to any one of items 1 to 9. Item 11: An energy storage device according to any one of items 1 to 10, wherein the thickness of the sealing plate is 1 mm or less. [Explanation of Symbols]

[0067] 10 Battery Case 12 Case body 14, 114 Sealing plate 14s ridge 14r, 114r recess SP1 1st slope SP2 2nd slope part 15 Liquid injection hole 16 Blind Rivets 16a Insertion part 16b Tsubabe 20 Electrode body 100 Energy Storage Devices

Claims

1. Electrode body and Electrolyte and A battery case containing the electrode body and the electrolyte, and having an injection hole, A blind rivet for sealing the injection hole, Equipped with, The aforementioned battery case is At the periphery of the injection hole, a raised portion is provided on the electrode body side, A recess is provided on the opposite side of the raised portion, and is recessed toward the electrode body at the periphery of the injection hole, It has, The aforementioned blind rivet is An insertion portion inserted into the aforementioned injection hole, A flange extending outward from one end of the insertion portion to the battery case, It has, The flange portion is housed within the recess of the battery case. Energy storage device.

2. The raised portion and the recessed portion are drawing portions. The energy storage device according to claim 1.

3. The depth of the recess is greater than the thickness of the battery case in the portion where the recess is provided. The energy storage device according to claim 1 or 2.

4. The aforementioned recess is A first inclined portion that is inclined toward the injection hole, A second inclined portion is provided on the outer edge side of the first inclined portion in the radial direction of the liquid injection hole, and is inclined toward the liquid injection hole at a different angle of inclination from the first inclined portion, Having, The energy storage device according to claim 1 or 2.

5. The second inclined section has a steeper gradient than the first inclined section. The energy storage device according to claim 4.

6. The outer shape of the first inclined portion is larger than the outer shape of the flange portion. The energy storage device according to claim 4.

7. In the axial direction of the liquid injection hole, the end of the flange portion on the battery case side is in a position that overlaps with the second inclined portion. The energy storage device according to claim 4.

8. The recess is provided along the periphery of the injection hole and further has a first flat portion that extends radially in the direction of the injection hole. The first inclined portion is provided along the outer edge of the first flat portion. The energy storage device according to claim 4.

9. The first inclined portion is provided along the outer edge of the liquid injection hole. The energy storage device according to claim 4.

10. The battery case comprises a case body having an opening and a sealing plate that seals the opening. The injection hole is provided in the sealing plate, The energy storage device according to claim 1 or 2.

11. The thickness of the sealing plate is 1 mm or less. The energy storage device according to claim 10.

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