Power storage device

Abstract

To enhance the productivity of a power storage device.SOLUTION: A power storage device 100 includes: a rectangular cylindrical case body 12, both ends thereof in a length direction Y being open; an electrode body 20 housed in the case body 12; a first lid 14a attached to an opening 12h1 at one end of the case body 12 in the length direction Y; and a second lid 14b attached to an opening 12h2 at another end of the case body 12 in the length direction Y. The case body 12 has a pair of opposed wide width surfaces 12b and a pair of opposed narrow width surfaces 12a continuous with the pair of wide width surfaces 12b. A plurality of projections 60 along the length direction Y of the case body 12 are formed on an inner side of at least a surface of the narrow width surfaces 12b and the wide width surfaces 12a of the case body 12.SELECTED DRAWING: Figure 6

Description

[Technical Field]

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

[0002] For example, Japanese Patent Application Laid-Open No. 2001-57179 discloses a secondary battery including an electrode stack and a battery case. The battery case includes a battery can that houses the electrode stack and a battery lid that seals the largest opening of the battery can. An X-shaped groove is formed on the outer surface of the battery can. This makes it difficult for the battery can to deform, even if the electrode stack expands.

[0003] For example, Japanese Patent Application Laid-Open Publication No. 2018-29006 discloses an electricity storage device including an electrode assembly, a cylindrical case body with a bottom that houses the electrode assembly, and a lid that closes the opening of the case body. The case body has a pair of long side walls. An insulating layer is provided inside the case body to cover the inner surface of the long side walls. The insulating layer is provided with a protrusion made of an amorphous carbon coating that extends in the depth direction of the case body. This makes it less likely that the corners on the bottom side of the electrode assembly will get caught on the insulating layer when the electrode assembly is inserted in the depth direction into the case body provided with the insulating layer. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-57179 [Patent Document 2] Japanese Patent Application Publication No. 2018-29006 Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, it is desired to improve the productivity of an electricity storage device in which an electrode body is inserted along the length of a rectangular cylindrical case body that is open at both ends. [Means for solving the problem]

[0006] The energy storage device disclosed herein includes a rectangular cylindrical case body with both ends open in the longitudinal direction, an electrode assembly housed in the case body, a first lid attached to the opening at one end of the case body in the longitudinal direction, and a second lid attached to the opening at the other end of the case body in the longitudinal direction. The case body has a pair of opposing wide sides and a pair of opposing narrow sides continuous with the pair of wide sides. A plurality of protrusions are formed on the inside of at least one of the narrow sides and the wide sides of the case body along the longitudinal direction of the case body.

[0007] According to the electricity storage device disclosed herein, when the electrode body is inserted into the case body, the electrode body comes into contact with the protrusions but does not come into contact with the inner surface of the case body excluding the protrusions. Therefore, when the electrode body is inserted into the case body, the contact area between the inner surface of the case body and the electrode body can be reduced. This makes it easier to insert the electrode body into the case body, thereby favorably improving the productivity of the electricity storage device. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view of a battery according to an embodiment. [Figure 2] FIG. 2 is a perspective view of the battery of FIG. 1 turned upside down. [Figure 3] FIG. 3 is a diagram showing the internal configuration of the battery of FIG. [Figure 4] FIG. 4 is a perspective view showing the electrode assembly attached to the first and second lids. [Figure 5] FIG. 5 is a perspective view showing a state in which the electrode body is being inserted into the case body. [Figure 6] FIG. 6 is a perspective view of the case body. [Figure 7] FIG. 7 is a diagram showing the narrow surface. [Figure 8] FIG. 8 is a diagram showing the broad surface. [Figure 9] FIG. 9 is a view of the narrow surface of FIG. 7 as seen from the left. [Figure 10] FIG. 10 is a view of the broad surface of FIG. 8 from the left. [Figure 11] FIG. 11 is a diagram showing the height of the protrusions extending in the Y direction. [Figure 12] FIG. 12 is a diagram showing a wide surface according to a modified example. [Figure 13] FIG. 13 is a diagram showing a wide surface according to a modified example. [Figure 14] FIG. 14 is a diagram showing the height of the convex portion according to the modified example. [Figure 15] FIG. 15 is a diagram showing the height of the convex portion according to the modified example. [Figure 16] FIG. 16 is a diagram showing the height of the convex portion according to the modified example. [Figure 17] FIG. 17 is a diagram showing the height of the convex portion according to the modified example. [Figure 18] FIG. 18 is a diagram showing the width of the convex portion according to the modified example. [Figure 19] FIG. 19 is a diagram showing the width of the convex portion according to the modified example. [Figure 20] FIG. 20 is a diagram showing the width of the convex portion according to the modified example. [Figure 21] FIG. 21 is a diagram showing the width of the convex portion according to the modified example. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, one embodiment of the technology disclosed herein will be described with reference to the drawings. It should be noted that the embodiment described here is not intended to limit the present invention in any way. Each drawing is a schematic diagram and does not necessarily faithfully reflect an actual product. Furthermore, the same reference numerals are appropriately used for components and parts that perform the same function, and redundant explanations will be omitted where appropriate.

[0010] In this specification, the term "electricity storage device" refers to a device that can be charged and discharged. Electricity storage devices include devices that can be repeatedly charged and discharged. Electricity storage devices include batteries such as primary batteries and secondary batteries (for example, non-aqueous electrolyte secondary batteries such as lithium ion secondary batteries, and nickel-metal hydride batteries), and capacitors (physical batteries) such as electric double layer capacitors. The electrolyte may be any of a liquid electrolyte (electrolytic solution), a gel electrolyte, and a solid electrolyte. Hereinafter, the electricity storage device disclosed herein will be described using a lithium ion secondary battery (hereinafter simply referred to as "battery 100") as an example.

[0011] FIG. 1 is a perspective view of a battery 100 according to this embodiment. FIG. 2 is a perspective view of the battery 100 of FIG. 1 turned upside down. FIG. 3 is a diagram showing the internal configuration of the battery 100 of FIG. 1. Here, the symbols F, Rr, L, R, U, and D in the drawings indicate the front, rear, left, right, top, and bottom of the battery 100, respectively. Furthermore, the symbols X, Y, and Z in the drawings indicate the short side direction, long side direction, and up-down direction of the battery 100, respectively. Here, the X direction is the front-to-back direction. The Y direction is the left-to-right direction and is perpendicular to the X direction. The Y direction is an example of the length direction. The Z direction is perpendicular to the X and Y directions. However, these directions are defined for convenience of explanation and do not limit the installation mode of the battery 100 in any way.

[0012] 3, the battery 100 includes a battery case 10, an electrode assembly 20, a positive electrode terminal 30, a negative electrode terminal 40, and an electrolyte (not shown). As described above, the battery 100 here is a lithium ion secondary battery.

[0013] The battery case 10 contains the electrode assembly 20 and an electrolyte solution. The battery case 10 is box-shaped. As shown in FIG. 1, the battery case 10 has a flat, rectangular parallelepiped (e.g., square) outer shape. The material from which the battery case 10 is formed is not particularly limited. The battery case 10 is preferably made of metal, such as aluminum, an aluminum alloy, iron, or an iron alloy.

[0014] In this embodiment, the battery case 10 includes a case body 12, a first lid body 14a, and a second lid body 14b, as shown in Fig. 3. The case body 12 is a rectangular cylindrical case with both ends in the Y direction open. The case body 12 extends in the Y direction. Here, an opening 12h1 is formed at one end side (here, the left end side) of the case body 12 in the Y direction. An opening 12h2 is formed at the other end side (here, the right end side) of the case body 12 in the Y direction.

[0015] As shown in FIG. 1, 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 constitute 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 upper side) is also referred to as a first narrow face 12a1. The narrow face 12a on the other side in the Z direction (here, the lower side) is also referred to as a second narrow face 12a2.

[0016] The wide surfaces 12b are generally 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. In this embodiment, the wide surface 12b on one side in the X direction (here, the front side) is also referred to as a first wide surface 12b1. The wide surface 12b on the other side in the X direction (here, the rear side) is also referred to as a second wide surface 12b2.

[0017] In this embodiment, the area of ​​the wide surface 12b is larger than the area of ​​the narrow surface 12a. The length of the wide surface 12b in the Z direction is longer than the length of the narrow surface 12a in the X direction. The case body 12 is formed, for example, by bending a single metal plate into a cylindrical shape and joining (for example, welding) the seams.

[0018] In this embodiment, as shown in FIG. 2 , a gas release valve 13 is provided on the second narrow surface 12a2. The gas release valve 13 is configured to break when the pressure inside the battery case 10 reaches a predetermined value or higher, thereby releasing gas inside the battery case 10 to the outside. Note that although the number of gas release valves 13 is one in this embodiment, there may be two or more. The gas release valve 13 may be provided on the first narrow surface 12a1. Furthermore, the position at which the gas release valve 13 is provided is not limited to the narrow surface 12a. The gas release valve 13 may be provided on a surface other than the narrow surface 12a, such as the wide surface 12b, the first cover 14a, or the second cover 14b. The area of ​​the gas release valve 13 is arbitrary. In this embodiment, the gas release valve 13 is a cross-shaped notch. However, the shape of the gas release valve 13 is not particularly limited. The gas release valve 13 may be, for example, a linear notch (only vertical or horizontal lines), or may be a conventionally known oval valve (with an internal notch) or a circular valve (with an internal notch), etc. The dimensions (length, depth) of the notch are arbitrary and can be determined appropriately taking into consideration, for example, the pressure resistance of the battery case 10.

[0019] The first lid body 14a and the second lid body 14b are attached to the case body 12. As shown in FIG. 3, the first lid body 14a is attached to an opening 12h1 at one end of the case body 12 in the Y direction. The first lid body 14a seals the opening 12h1. The second lid body 14b is attached to an opening 12h2 at the other end of the case body 12 in the Y direction. The second lid body 14b seals the opening 12h2. The first lid body 14a and the second lid body 14b have shapes corresponding to the openings 12h1 and 12h2, respectively, in other words, shapes that match the openings 12h1 and 12h2. In this embodiment, the first lid body 14a and the second lid body 14b are substantially rectangular plate-like members. Here, the area of ​​each of the first lid body 14a and the second lid body 14b is smaller than the area of ​​the wide surface 12b and smaller than the area of ​​the narrow surface 12a. The battery case 10 is integrated by joining (e.g., welding) the first lid body 14a and the second lid body 14b to the peripheries of a pair of openings 12h1 and 12h2 of the case body 12, respectively. This allows the battery case 10 to be hermetically sealed (sealed).

[0020] In this embodiment, as shown in FIG. 1 , the second cover 14b has a liquid inlet 15. However, the liquid inlet 15 may also be formed in the first cover 14a. The liquid inlet 15 may also be formed in the case body 12. In this embodiment, the liquid inlet 15 is formed on a surface different from the gas release valve 13, but may also be formed on the same surface as the gas release valve 13. The liquid inlet 15 is a hole for injecting the electrolyte into the battery case 10 after the first cover 14a and the second cover 14b are assembled to the case body 12. The liquid inlet 15 is sealed with a sealing member 16 after the electrolyte is injected. In this embodiment, the liquid inlet 15 is formed in the second cover 14b, but may also be formed in the first cover 14a. The liquid inlet 15 may also be formed in the case body 12. In this embodiment, the liquid inlet 15 is formed on a surface different from the gas release valve 13, but may also be formed on the same surface as the gas release valve 13.

[0021] As shown in FIG. 1 , the positive electrode terminal 30 and the negative electrode terminal 40 are each fixed to the battery case 10. Here, the positive electrode terminal 30 and the negative electrode terminal 40 are provided on opposing surfaces of the battery case 10. In this embodiment, the positive electrode terminal 30 is attached to the second lid body 14b located on the other side in the Y direction (here, the right side). As shown in FIG. 2 , the negative electrode terminal 40 is attached to the first lid body 14a located on one side in the Y direction (here, the left side). However, the positive electrode terminal 30 and the negative electrode terminal 40 may also be provided on the case main body 12. Furthermore, in this embodiment, the positive electrode terminal 30 and the negative electrode terminal 40 are provided on a surface of the battery case 10 different from the gas release valve 13, but they may also be provided on the same surface of the battery case 10 as the gas release valve 13. The positive electrode terminal 30 and the negative electrode terminal 40 may also be provided on the same surface of the battery case 10.

[0022] As shown in FIG. 3 , the positive electrode terminal 30 and the negative electrode terminal 40 are exposed to the outside of the battery case 10. Specifically, the positive electrode terminal 30 and the negative electrode terminal 40 are exposed to the outside of the first lid body 14a and the second lid body 14b, respectively. Here, the positive electrode terminal 30 and the negative electrode terminal 40 are arranged on an axis extending in the Z direction and passing through the center of the first lid body 14a (or the second lid body 14b). However, the axis on which the positive electrode terminal 30 and the negative electrode terminal 40 are arranged may be offset from the center of the first lid body 14a and the second lid body 14b, for example, in the X direction or the Z direction. Furthermore, the positive electrode terminal 30 and the negative electrode terminal 40 do not have to be arranged on the same axis. For example, one of the positive electrode terminal 30 and the negative electrode terminal 40 may be offset to one side in the X direction, and the other may be offset to the other side in the X direction.

[0023] The positive electrode terminal 30 is preferably made of a metal, more preferably aluminum or an aluminum alloy, for example, and the negative electrode terminal 40 is preferably made of a metal, more preferably copper or a copper alloy, for example.

[0024] As shown in Fig. 3, the positive electrode terminal 30 is electrically connected to the positive electrode 21 of the electrode assembly 20 via a positive electrode current collector 32 inside the battery case 10. The negative electrode terminal 40 is electrically connected to the negative electrode 22 of the electrode assembly 20 via a negative electrode current collector 42 inside the battery case 10. The positive electrode terminal 30 and the negative electrode terminal 40 are insulated from the case body 12 by an insulating film 50. The positive electrode terminal 30 and the negative electrode terminal 40 are insulated from the first lid body 14a and the second lid body 14b by an insulating member 55 (see Fig. 4).

[0025] As shown in Fig. 3, the electrode body 20 is housed inside the battery case 10 (in other words, the case body 12). Fig. 4 is a perspective view showing the electrode body 20 attached to the first lid body 14a and the second lid body 14b. As shown in Fig. 4, the electrode body 20 is covered with an insulating film 50 and placed inside the battery case 10. In Fig. 4, one electrode body 20 is housed inside one battery case 10. However, the number of electrode bodies 20 housed in one battery case 10 is not particularly limited, and there may be more than one.

[0026] As shown in Fig. 3, the electrode assembly 20 has a positive electrode 21 and a negative electrode 22. In this embodiment, the electrode assembly 20 is a so-called wound electrode assembly. The electrode assembly 20 is formed by winding a laminate formed by stacking a strip-shaped positive electrode 21 and a strip-shaped negative electrode 22 with a strip-shaped separator (not shown) interposed therebetween in the longitudinal direction around a winding axis. However, the electrode assembly 20 may also be a laminated electrode assembly formed by stacking a rectangular positive electrode and a rectangular negative electrode in an insulated state.

[0027] In this embodiment, the electrode body 20 has a flat outer shape. Although not shown, the electrode body 20 has a pair of curved portions and a pair of flat surfaces connecting the pair of curved portions. Here, the electrode body 20 is housed inside the battery case 10 with the winding axis oriented along the Y direction. The pair of curved portions of the electrode body 20 face a pair of narrow surfaces 12a of the case main body 12, respectively. However, the electrode body 20 may also be housed inside the battery case 10 with the winding axis oriented along the Z direction. Each of the components constituting the electrode body 20 (such as the positive electrode 21, negative electrode 22, and separator) may be similar to those of a general secondary battery and is not particularly limited.

[0028] The positive electrode 21 includes, for example, a positive electrode current collector and a positive electrode active material layer fixed to at least one surface of the positive electrode current collector. The positive electrode current collector is strip-shaped here. The positive electrode current collector is made of a conductive metal such as aluminum, an aluminum alloy, nickel, or stainless steel. Here, the positive electrode current collector is a metal foil, specifically, an aluminum foil.

[0029] The positive electrode active material layer is provided in a strip-like shape along the longitudinal direction of the strip-shaped positive electrode current collector. The positive electrode active material layer contains a positive electrode active material capable of reversibly absorbing and releasing charge carriers. The positive electrode active material is preferably an oxide containing at least one of Ni, Co, and Mn, and examples thereof include lithium transition metal composite oxides such as lithium cobalt oxide, lithium manganese oxide, lithium nickel oxide, lithium nickel manganese composite oxide, and lithium nickel cobalt composite oxide. The positive electrode active material preferably includes, for example, a composite oxide containing Ni and Li, in which the Ni content in the composite oxide is in the range of 70 mol% to 100 mol% relative to the total number of moles of the constituent elements excluding Li and oxygen in the composite oxide. Positive electrode active materials also include those in which a portion of the Ni, Co, and Mn is replaced with Al, Ti, Zr, P, B, Si, Nb, C, etc., or those in which the particle surface is covered with a compound containing Al, Ti, Zr, W, P, B, Si, Nb, C, etc. The total amount of substitution and addition is about 0.1 mol % to 7 mol %.

[0030] The negative electrode 22 includes, for example, a negative electrode current collector and a negative electrode active material layer fixed to at least one surface of the negative electrode current collector. The negative electrode current collector is strip-shaped here. The negative electrode current collector is made of a conductive metal such as copper, a copper alloy, nickel, or stainless steel. Here, the negative electrode current collector is a metal foil, specifically, a copper foil.

[0031] The negative electrode active material layer is provided in a strip shape along the longitudinal direction of the strip-shaped negative electrode current collector. The negative electrode active material layer contains a negative electrode active material capable of reversibly absorbing and releasing charge carriers. Examples of the negative electrode active material include carbon materials such as graphite and carbon, and metals capable of absorbing lithium such as Si, SiO, SiC, and Sn, and compounds thereof.

[0032] The separator is a member that insulates the positive electrode active material layer from the negative electrode active material layer. A porous resin sheet made of a polyolefin resin such as polyethylene (PE) or polypropylene (PP) is suitable as the separator. A heat-resistant layer (HRL) containing an inorganic filler may be provided on the surface of the separator. Examples of inorganic fillers that can be used include alumina, boehmite, aluminum hydroxide, and titania.

[0033] As shown in FIG. 3 , the electrode assembly 20 includes a positive electrode tab 23 and a negative electrode tab 24 extending in opposite directions. The positive electrode tab 23 extends from an end of a first side (here, the right side) of the electrode assembly 20 toward the first side and constitutes a part of the positive electrode 21. The positive electrode tab 23 is a portion where no positive electrode active material layer is formed and the positive electrode current collector is exposed. The positive electrode tab 23 is configured by stacking multiple layers of positive electrode current collectors protruding toward the first side. A positive electrode current collector 32 is connected to the positive electrode tab 23, and a positive electrode terminal 30 is connected via the positive electrode current collector 32. The negative electrode tab 24 extends from an end of a second side (here, the left side) of the electrode assembly 20 toward the second side and constitutes a part of the negative electrode 22. The negative electrode tab 24 is a portion where no negative electrode active material layer is formed and the negative electrode current collector is exposed. The negative electrode tab 24 is configured by stacking multiple layers of negative electrode current collectors protruding to the second side. A negative electrode current collector 42 is connected to the negative electrode tab 24, and a negative electrode terminal 40 is connected via the negative electrode current collector 42.

[0034] The electrolyte solution is accommodated inside the battery case 10 together with the electrode assembly 20. The electrolyte solution may be the same as that used in general secondary batteries and is not particularly limited. The electrolyte solution is typically a non-aqueous liquid electrolyte (nonaqueous electrolyte solution) containing a non-aqueous solvent and a supporting salt. The non-aqueous solvent contains, for example, carbonates such as ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC). The non-aqueous solvent is preferably a mixture of EC, EMC, and DMC in a range of 1% to 99% by volume, with the total ratio being 100%. The supporting salt is, for example, a fluorine-containing lithium salt. The fluorine-containing lithium salt preferably contains lithium hexafluorophosphate (LiPF6), lithium bis(fluorosulfonyl)imide (F2LiNO4S2), also known as LiFSI, or a mixture thereof. The concentration of the supporting salt is preferably 0.6 mol to 1.8 mol per 1 L of non-aqueous solvent.

[0035] In this embodiment, as shown in FIG. 3, the electrode assembly 20 has an insulating film 50. The insulating film 50 is housed inside the battery case 10 together with the electrode assembly 20. The insulating film 50 is disposed between the battery case 10 and the electrode assembly 20. As shown in FIG. 4, the insulating film 50 covers the periphery of the electrode assembly 20. Specifically, it is preferable that the insulating film 50 covers at least the curved portion facing one narrow surface 12a of the electrode assembly 20 and the pair of flat surfaces. The insulating film 50 is made of a single sheet-like member assembled into, for example, a box- or bag-like shape.

[0036] The above describes part of the configuration of the battery 100 according to this embodiment. FIG. 5 is a perspective view showing the state in which the electrode assembly 20 is being inserted into the case body 12. When fabricating the battery 100, the electrode assembly 20 is inserted into the battery case 10 in the insertion direction D1 as shown in FIG. 5, thereby housing the electrode assembly 20 in the battery case 10. For example, in the battery case 10, before the first lid 14a and the second lid 14b are assembled to the case body 12, the electrode assembly 20 is inserted into the case body 12 through either the opening 12h1 or the opening 12h2. In the example shown in FIG. 5, the electrode assembly 20 is inserted into the case body 12 through the opening 12h1. At this time, it may be difficult to insert the electrode assembly 20 into the case body 12. In particular, as shown in FIG. 4, if the electrode assembly 20 is inserted into the case body 12 while covered with the insulating film 50, the insulating film 50 will come into direct contact with the case body 12. Because the insulating film 50 is relatively thin, problems such as bending may occur if the insulating film 50 is inserted while in contact with the case body 12. In the following description, the electrode body 20 contacting the case body 12 includes the state in which the insulating film 50 contacts the case body 12.

[0037] In this embodiment, when manufacturing the battery 100, the contact area between the electrode body 20 and the case body 12 during insertion is reduced to facilitate insertion of the electrode body 20 into the case body 12. This reduces the dynamic frictional force when inserting the electrode body 20 into the case body 12. Therefore, since it becomes easier to insert the electrode body 20 into the case body 12, the productivity of the battery 100 can be improved.

[0038] Next, the configuration of the case body 12 will be described in detail as a configuration for improving the productivity of the battery 100. FIG. 6 is a perspective view of the case body 12. FIG. 7 is a view showing the narrow surface 12a. FIG. 8 is a view showing the wide surface 12b. In this embodiment, as shown in FIG. 6, the case body 12 has a plurality of protrusions 60. Note that the protrusions 60 are omitted in FIG. 5. As shown in FIGS. 7 and 8, the protrusions 60 extend along the Y direction. The plurality of protrusions 60 are formed on the inside of at least one of the pair of narrow surfaces 12a and the pair of wide surfaces 12b. In the following description, the term "inside" will be omitted where appropriate for protrusions 60 formed on the inside of a surface.

[0039] As shown in Fig. 6, for example, the plurality of protrusions 60 are formed on at least one of the pair of narrow surfaces 12a. In this embodiment, the plurality of protrusions 60 are formed on each of the pair of narrow surfaces 12a. Also, for example, the plurality of protrusions 60 are formed on at least one of the pair of wide surfaces 12b. In this embodiment, the plurality of protrusions 60 are formed on each of the pair of wide surfaces 12b.

[0040] In the following description, the convex portion 60 formed on the narrow surface 12a will be referred to as a narrow convex portion 61. Of the narrow convex portions 61, the narrow convex portion 61 formed on the first narrow surface 12a1 will be referred to as a first narrow convex portion 61a, and the narrow convex portion 61 formed on the second narrow surface 12a2 will be referred to as a second narrow convex portion 61b. Also, the convex portion 60 formed on the wide surface 12b will be referred to as a wide convex portion 62. Of the wide convex portions 62, the wide convex portion 62 formed on the first wide surface 12b1 will be referred to as a first wide convex portion 62a, and the wide convex portion 62 formed on the second wide surface 12b2 will be referred to as a second wide convex portion 62b. Herein, in the common description of the first narrow convex portion 61a and the second narrow convex portion 61b, the term narrow convex portion 61 will be used as appropriate. In a common description of the first wide convex portion 62a and the second wide convex portion 62b, the term wide convex portion 62 is used as appropriate. In a common description of the narrow convex portion 61 and the wide convex portion 62, the term convex portion 60 is used as appropriate.

[0041] In this embodiment, as shown in FIG. 6 , a plurality of convex portions 60 are formed on each of the pair of narrow surfaces 12a and the pair of wide surfaces 12b. Specifically, two first narrow convex portions 61a are formed on the first narrow surface 12a1, and two second narrow convex portions 61b are formed on the second narrow surface 12a2. Two first wide convex portions 62a are formed on the first wide surface 12b1, and two second wide convex portions 62b are formed on the second wide surface 12b2. However, here, the number of first narrow convex portions 61a, second narrow convex portions 61b, first wide convex portions 62a, and second wide convex portions 62b is not limited to two, and may be three or more. The number of first narrow convex portions 61a, second narrow convex portions 61b, first wide convex portions 62a, and second wide convex portions 62b may be the same or different.

[0042] In this embodiment, as shown in FIGS. 7 and 8, the first narrow convex portion 61a, the second narrow convex portion 61b, the first wide convex portion 62a, and the second wide convex portion 62b have the same shape and size, but may have different shapes and sizes. Here, the convex portion 60 is linear and extends in the Y direction. The convex portion 60 extends linearly. However, at least a portion of the convex portion 60 may be curved. Here, the convex portion 60 extends from one end (here, the left end) of the case body 12 in the Y direction to the other end (here, the right end) in the Y direction. For example, as shown in FIG. 7, the narrow convex portion 61 extends from one end to the other end of the narrow face 12a in the Y direction. As shown in FIG. 8, the wide convex portion 62 extends from one end to the other end of the wide face 12b in the Y direction. In this embodiment, the length of the convex portion 60 in the Y direction is the same as the length of the case body 12 in the Y direction.

[0043] Fig. 9 is a view of the narrow surface 12a of Fig. 7 as seen from the left. Fig. 10 is a view of the wide surface 12b of Fig. 8 as seen from the left. As shown in Figs. 9 and 10, the vertical cross section of the protrusion 60 is semicircular. The protrusion 60 is formed by a curved surface that protrudes inward from the case body 12. However, the vertical cross section of the protrusion 60 is not particularly limited and may be, for example, rectangular.

[0044] In this embodiment, as shown in FIGS. 7 and 8, each protrusion 60 has the same width. The protrusion 60 has the same width at any position in the Y direction. The width of the protrusion 60 here refers to the length of the protrusion 60 in a direction perpendicular to the Y direction, i.e., the length of the short side of the protrusion 60. For example, as shown in FIG. 7, the width W11 of the narrow protrusion 61 refers to the length in the X direction. As shown in FIG. 8, the width W12 of the wide protrusion 62 refers to the length in the Z direction. Here, as shown in FIG. 7, the width W11 of each narrow protrusion 61 is less than ½, preferably ⅓ or less, and particularly preferably ¼ or less, of the length W21 of the narrow surface 12a in the X direction. As shown in FIG. 8, the width W12 of each wide protrusion 62 is less than ½, preferably ⅕ or less, and particularly preferably ¼ or less, of the length W22 of the wide surface 12b in the Z direction. The total surface area of ​​the plurality of narrow protrusions 61 formed on one narrow surface 12a is less than 1 / 2 of the area of ​​one narrow surface 12a, preferably 1 / 3 or less, and particularly preferably 1 / 4 or less. The total surface area of ​​the plurality of wide protrusions 62 formed on one wide surface 12b is less than 1 / 2 of the area of ​​one wide surface 12b, preferably 1 / 5 or less, and particularly preferably 1 / 10 or less.

[0045] FIG. 11 is a diagram showing the height of a protrusion 60 extending in the Y direction. In this embodiment, as shown in FIG. 11, the height of each protrusion 60 is the same. The protrusion 60 has the same height at any position in the Y direction. Here, the height of the protrusion 60 refers to the length of the highest point of the protrusion 60. Here, the height of the protrusion 60 can be rephrased as the thickness of the protrusion 60. For example, as shown in FIG. 9, the height H11 of the narrow protrusion 61 is 0.5 times or more, preferably 0.8 times or more, and particularly preferably 1 time or more, the thickness H21 of the narrow surface 12a. Similarly, as shown in FIG. 10, the height H12 of the wide protrusion 62 is 0.5 times or more, preferably 0.8 times or more, and particularly preferably 1 time or more, the thickness H22 of the wide surface 12b.

[0046] 7 and 8, in this embodiment, at least one protrusion 60 is formed on a cross section taken along the circumferential direction of the case body 12 at any position in the Y direction of the case body 12. In other words, at least one protrusion 60 is formed at any position in the Y direction of the case body 12. Therefore, when the electrode body 40 is inserted into the case body 12, it is configured to always come into contact with at least one of the multiple protrusions 60.

[0047] The protrusion 60 is formed from the same material as the case body 12. In this embodiment, the case body 12 is formed from a metal such as aluminum, an aluminum alloy, iron, or an iron alloy. Therefore, the protrusion 60 is formed from the same metal as the case body 12. Here, the protrusion 60 is fixed to the case body 12 and is formed integrally with the case body 12. Here, the protrusion 60 being fixed to the case body 12 refers to a state in which the protrusion 60 cannot be separated from the case body 12 without using a tool or the like. When the protrusion 60 is fixed to the case body 12, a worker cannot separate the protrusion 60 from the case body 12 by hand alone. As will be described in detail later, at least one of the multiple protrusions 60 may be formed from a weld mark, i.e., a bead, formed during welding when the case body 12 is fabricated.

[0048] Next, an example of a method for manufacturing the battery 100 will be described. First, a single metal plate is prepared, and the case body 12 is fabricated from the metal plate. A narrow protrusion 61 is formed in the metal plate at a portion corresponding to the narrow surface 12a, and a wide protrusion 62 is formed in the metal plate at a portion corresponding to the wide surface 12b, thereby forming a protrusion 60 on the metal plate. The method for forming the protrusion 60 is not particularly limited, and the protrusion 60 may be formed by drawing or extruding the metal plate. The protrusion 60 may also be formed by plastic processing such as rolling. Next, the gas release valve 13 is formed at a predetermined position on the metal plate by a conventionally known method. The metal plate with the protrusion 60 and the gas release valve 13 formed thereon is then bent into a cylindrical shape, and the seams are joined (for example, welded). The bead formed when the joint is welded may be one of the multiple protrusions 60. The protrusion 60 formed by a bead may be formed by grinding the bead to make it uniform in height. In this way, the case body 12 as shown in FIG. 6 can be produced.

[0049] Next, an electrode assembly 20 manufactured by a conventional method is prepared. Then, as shown in FIG. 3, a positive electrode current collector 32 and a negative electrode current collector 42 are joined to the positive electrode tab 23 and the negative electrode tab 24, respectively. The negative electrode terminal 40 provided on the first lid 14a is joined to the negative electrode current collector 42 to form an integrated assembly. This integrated assembly is then inserted into the case body 12 manufactured as described above. The positive electrode tab 23 is then joined to the positive electrode terminal 30 provided on the second lid 14b. The case body 12 is then joined to the first lid 14a and the second lid 14b, respectively. Finally, the battery 100 can be fabricated by injecting an electrolyte solution through the inlet.

[0050] As described above, in this embodiment, as shown in Fig. 3, the battery 100 includes a rectangular cylindrical case body 12 with both ends open in the Y direction, an electrode assembly 20 housed in the case body 12, a first lid body 14a attached to an opening 12h1 at one end (here, the left side) of the case body 12 in the Y direction, and a second lid body 14b attached to an opening 12h2 at the other end (here, the right side) of the case body 12 in the Y direction. As shown in Fig. 6, the case body 12 has a pair of opposing wide surfaces 12b and a pair of opposing narrow surfaces 12a continuous with the pair of wide surfaces 12b. A plurality of protrusions 60 are formed on the inside of at least one of the narrow surfaces 12a and the wide surfaces 12b of the case body 12 along the Y direction of the case body 12. As a result, as shown in Fig. 5, when the electrode body 20 is inserted into the case body 12, the electrode body 20 comes into contact with the protrusion 60 but does not come into contact with the inner surface of the case body 12 excluding the protrusion 60. Therefore, when the electrode body 20 is inserted into the case body 12, the contact area between the inner surface of the case body 12 and the electrode body 20 can be reduced. This makes it possible to reduce the resistance between the electrode body 20 and the case body 12 in the insertion direction. This makes it easier to insert the electrode body 20 into the case body 12, thereby favorably improving the productivity of the battery 100.

[0051] In this embodiment, as shown in FIG. 6 , a plurality of protrusions 60 (here, narrow protrusions 61) are formed on at least one of the pair of narrow surfaces 12a. Here, a plurality of protrusions 60 are formed on each of both narrow surfaces 12a of the pair of narrow surfaces 12a. For example, when inserting the electrode body 20 into the case body 12 with the case body 12 oriented as shown in FIG. 5 , the weight of the electrode body 20 is likely to be applied to the narrow surface 12a. Even in this case, since a plurality of protrusions 60 are formed on the narrow surface 12a, the resistance between the electrode body 20 and the case body 12 (specifically, the narrow surface 12a) during insertion of the electrode body 20 can be reduced. This makes it easier to insert the electrode body 20 into the case body 12.

[0052] In this embodiment, as shown in Fig. 6, a plurality of protrusions 60 (here, wide protrusions 62) are formed on at least one of the pair of wide surfaces 12b. Here, a plurality of protrusions 60 are formed on each of the pair of wide surfaces 12b. This makes it possible to reduce the resistance between the electrode body 20 and the wider surface 12b when inserting the electrode body 20 into the case body 12. This makes it possible to easily insert the electrode body 20 into the case body 12.

[0053] 7 and 8 , in the present embodiment, a protrusion 60 is formed on a cross section of the case body 12 along the circumferential direction at any position in the Y direction of the case body 12. This allows the electrode body 20 to maintain contact with at least one of the multiple protrusions 60 while the electrode body 20 is being inserted into the case body 12. Therefore, while the electrode body 20 is being inserted into the case body 12, the contact area between the inner surface of the case body 12 and the electrode body 20 can be reduced. This makes it easier to insert the electrode body 20 into the case body 12.

[0054] In this embodiment, the protrusions 60 are formed from the same material as the case body 12. This allows the protrusions 60 to be formed from the case body 12. Therefore, it is not necessary to form the protrusions 60 from a material other than the material that forms the case body 12, and the protrusions 60 can be formed in the process of forming the case body 12.

[0055] The configuration of the battery 100 has been described above. Note that the number, position, and shape of the protrusions 60 are not limited to those of the above embodiment. Next, modified examples of the protrusions 60 will be described. Below, modified examples of the protrusions 60 (wide protrusions 62 in this case) formed on the wide surface 12b will be described, but the same applies to modified examples of the protrusions 60 (narrow protrusions 61 in this case) formed on the narrow surface 12a. In the following description, by appropriately replacing the wide surface 12b with the narrow surface 12a, modified examples of the narrow protrusions 61 can be obtained.

[0056] 12 and 13 are diagrams illustrating a wide surface 12b according to a modified example. As illustrated in FIG. 12, one protrusion 60A does not have to extend to both ends of the case body 12 in the Y direction. That is, the length of the protrusion 60A in the Y direction may be shorter than the length of the case body 12 in the Y direction. In the example illustrated in FIG. 12, the lengths of the multiple protrusions 60A formed on the wide surface 12b in the Y direction may be the same or different. The multiple protrusions 60A may also be arranged in a staggered pattern on the wide surface 12b. For example, the multiple protrusions 60A aligned in the Y direction may be offset in the width direction of the wide surface 12b (here, the Z direction). The multiple protrusions 60A may also be aligned in the width direction of the wide surface 12b at the same position in the Y direction on the wide surface 12b. Even in the example illustrated in FIG. 12, at least one protrusion 60 may be formed at any position in the Y direction on the wide surface 12b.

[0057] 13, the plurality of protrusions 60B may be randomly arranged on the wide surface 12b. That is, the plurality of protrusions 60B formed on the wide surface 12b may not have uniform positions in the Y direction and in the width direction of the wide surface 12b. In this case, the lengths of the plurality of protrusions 60B in the Y direction may be different for some, all, or all the same. The plurality of protrusions 60B formed on the wide surface 12b may have different positions at one end in the Y direction and different positions at the other end in the Y direction.

[0058] 12 and 13, even when the plurality of protrusions 60A, 60B are arranged in a staggered or random pattern, the contact area between the inner surface of the case body 12 and the electrode body 20 can be reduced when the electrode body 20 is inserted into the case body 12. This reduces the resistance between the electrode body 20 and the case body 12 in the insertion direction D1 (see FIG. 5). This makes it easier to insert the electrode body 20 into the case body 12, thereby favorably improving the productivity of the battery 100.

[0059] 14 to 17 are diagrams showing the heights of protrusions 60C to 60F according to modified examples. For example, as shown in Fig. 14, protrusion 60C may be configured so that its height decreases from one end (here, the left end) to the other end (here, the right end) in the Y direction. As shown in Fig. 15, protrusion 60D may be configured so that its height increases from one end to the other end in the Y direction.

[0060] 16 and 17, point P indicates a reference point. Reference point P1 is located between one end and the other end of wide surface 12b in the Y direction. Here, reference point P1 is the center point of wide surface 12b in the Y direction. However, reference point P1 may be a point shifted in the Y direction from the center point of wide surface 12b in the Y direction. As shown in FIG. 16, protrusion 60E may have a height that increases from one end (here, the left end) in the Y direction toward reference point P1. In this case, protrusion 60E may have a height that decreases from reference point P1 toward the other end (here, the right end) in the Y direction. In other words, protrusion 60E may be configured to have the highest height at the position of reference point P1.

[0061] 17, the height of the protrusion 60F may decrease from one end in the Y direction toward the reference point P1. In this case, the height of the protrusion 60F may increase from the reference point P1 toward the other end in the Y direction. In other words, the protrusion 60F may be configured so that its height is lowest at the position of the reference point P1.

[0062] 18 to 21 are diagrams showing the widths of protrusions 60G to 60J according to modified examples, and are diagrams showing the wide surface 12b. As shown in Fig. 18, protrusion 60G may be configured so that its width (here, its length in the Z direction) decreases from one end to the other in the Y direction. As shown in Fig. 19, protrusion 60H may be configured so that its width increases from one end to the other in the Y direction.

[0063] 20, the width of the protrusion 60I may increase from one end (here, the left end) in the Y direction toward the reference point P1. In this case, the width of the protrusion 60I may decrease from the reference point P1 toward the other end (here, the right end) in the Y direction. In other words, the protrusion 60I may be configured so that its width is greatest at the position of the reference point P1.

[0064] 21, the width of the protrusion 60J may decrease from one end in the Y direction toward the reference point P1. In this case, the width of the protrusion 60J may increase from the reference point P1 toward the other end in the Y direction. In other words, the protrusion 60J may be configured so that its width is smallest at the position of the reference point P1.

[0065] Although not shown in the drawings, the protrusions 60 may be configured so that their heights change from one end to the other end in the Y direction. That is, the protrusions 60 may be configured so that their heights increase or decrease from one end to the other end in the Y direction. In other words, the height of the protrusions 60 may be high in one portion in the Y direction and low in another portion. Although not shown in the drawings, the protrusions 60 may be configured so that their widths change from one end to the other end in the Y direction. That is, the protrusions 60 may be configured so that their widths increase or decrease from one end to the other end in the Y direction. For example, the width of the protrusions 60 may be large in one portion in the Y direction and small in another portion. Note that the one portion and the other portions may be alternately arranged in the Y direction.

[0066] Battery 100 can be used for a variety of purposes, but can be suitably used, for example, as a power source (driving power source) for motors mounted on vehicles such as passenger cars, trucks, etc. The type of vehicle is not particularly limited, but examples include plug-in hybrid electric vehicles (PHEVs), hybrid electric vehicles (HEVs), battery electric vehicles (BEVs), etc.

[0067] 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.

[0068] As described above, this specification includes the disclosures set forth in the following sections.

[0069] Section 1: a rectangular cylindrical case body having open ends in the length direction; an electrode body housed in the case body; a first cover attached to an opening at one end of the case body in the longitudinal direction; a second cover attached to an opening on the other end side of the case body in the length direction; Equipped with The case body includes: A pair of opposing wide surfaces; a pair of opposing narrow surfaces continuous with the pair of wide surfaces; and An electricity storage device, wherein a plurality of protrusions are formed on the inside of at least one of the narrow side and the wide side of the case body along the length direction of the case body.

[0070] Section 2: Item 2. The electricity storage device according to item 1, wherein the plurality of protrusions are formed on at least one of the pair of narrow surfaces.

[0071] Section 3: Item 3. The electricity storage device according to item 2, wherein the plurality of protrusions are formed on each of the pair of narrow surfaces.

[0072] Section 4: 4. The power storage device according to any one of items 1 to 3, wherein the plurality of protrusions are formed on at least one of the pair of wide surfaces.

[0073] Section 5: Item 5. The electricity storage device according to item 4, wherein a plurality of the protrusions are formed on each of the pair of wide surfaces.

[0074] Item 6: 6. The electricity storage device according to any one of items 1 to 5, wherein the plurality of protrusions are arranged in a staggered pattern or randomly.

[0075] Section 7: 7. The electric storage device according to any one of items 1 to 6, wherein the convex portion is formed on a cross section along a circumferential direction of the case body at any position in the longitudinal direction of the case body.

[0076] Section 8: 8. The electricity storage device according to any one of items 1 to 7, wherein the protrusion is formed from the same material as the case body. [Explanation of symbols]

[0077] 100 Batteries (energy storage devices) 12 Case body 12a narrow side 12b wide face 14a First lid 14b Second cover 20 Electrode body 60 Convex part

Claims

1. a rectangular cylindrical case body having open ends in the length direction; an electrode body housed in the case body; a first cover attached to an opening at one end of the case body in the longitudinal direction; a second cover attached to an opening at the other end of the case body in the longitudinal direction; Equipped with The case body includes: A pair of opposing wide surfaces; a pair of opposing narrow surfaces continuous with the pair of wide surfaces; and An electricity storage device, wherein a plurality of protrusions are formed on the inside of at least one of the narrow side and the wide side of the case body along the length direction of the case body.

2. The power storage device according to claim 1 , wherein the plurality of protrusions are formed on at least one of the pair of narrow surfaces.

3. The power storage device according to claim 2 , wherein a plurality of the protrusions are formed on each of the pair of narrow surfaces.

4. The power storage device according to claim 1 , wherein the plurality of protrusions are formed on at least one of the pair of wide surfaces.

5. The power storage device according to claim 4 , wherein a plurality of the protrusions are formed on each of the pair of wide surfaces.

6. The power storage device according to claim 1 , wherein the plurality of protrusions are arranged in a staggered pattern or randomly.

7. The electricity storage device according to claim 1 , wherein the protrusion is formed on a cross section of the case body taken along a circumferential direction at any position in the longitudinal direction of the case body.

8. The electricity storage device according to claim 1 , wherein the protrusion is made of the same material as the case body.

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