Power storage device

Abstract

To provide a technique capable of suitably enhancing the productivity of a power storage device.SOLUTION: A power storage device 100 disclosed herein 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 at one end of the case body 12 in the length direction Y; and a second lid 14b attached to an opening at another end of the case body 12 in the length direction Y. The case body 12 includes 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 recessed part 12a1 configured to elongate along the length direction of the case body 12 is present at an inner side of at least one narrow width surface 12a of the pair of narrow width surfaces 12a.SELECTED DRAWING: Figure 5

Description

[Technical Field]

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

[0002] Japanese Patent Publication No. 2001-57179 discloses a secondary battery equipped with a battery case consisting of a battery can and a battery lid that seals the largest opening of the battery can. Chinese Utility Model No. 219017778 discloses a battery having a battery case with a housing and end caps, where the outer walls of the housing include a bottom wall, two first side walls arranged opposite each other, and two second side walls arranged opposite each other, and the two first side walls face the largest surface of the electrode assembly. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-57179 [Patent Document 2] Chinese Utility Model No. 219017778 Summary of the Invention [Problem to be solved by the invention]

[0004] However, it is desirable 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]

[0005] The disclosed electric storage device includes a rectangular cylindrical case body with openings on both longitudinal ends, an electrode assembly housed in the case body, a first lid attached to the opening at one longitudinal end of the case body, and a second lid attached to the opening at the other longitudinal end of the case body. The case body also has a pair of opposing wide sides and a pair of opposing narrow sides that are continuous with the pair of wide sides. A recess extending along the longitudinal direction of the case body is present on the inside of at least one of the pair of narrow sides. This electric storage device can be advantageously manufactured with improved productivity. [Brief explanation of the drawings]

[0006] [Figure 1] FIG. 1 is a perspective view schematically showing a battery according to one embodiment. [Figure 2] FIG. 2 is a perspective view of the battery of FIG. 1 turned upside down. [Figure 3] FIG. 3 is a vertical cross-sectional view schematically showing the internal structure of the battery of FIG. [Figure 4] FIG. 4 is a perspective view schematically showing an electrode body attached to a lid body. [Figure 5] FIG. 5 is a schematic diagram showing the configuration of a case main body according to one embodiment. [Figure 6] FIG. 6 is a schematic diagram showing insertion of an electrode assembly into a case body according to one embodiment. [Figure 7] FIG. 7 is a schematic diagram showing an aspect in which the electrode body is inserted into the case body of FIG. [Figure 8] FIG. 8 is an explanatory diagram for explaining the vicinity of the recessed portion in FIG. [Figure 9] FIG. 9 is an explanatory diagram for explaining the restraint of the battery according to one embodiment. [Figure 10] FIG. 10 is an explanatory diagram for explaining a case where a recess exists on a wide surface. [Figure 11] FIG. 11 is a diagram corresponding to the area enclosed by the dashed circle in FIG. 5 according to the second embodiment. [Figure 12]FIG. 12 is a diagram corresponding to the area enclosed by the dashed circle in FIG. 5 according to the third embodiment. [Figure 13] FIG. 13 is a diagram corresponding to the area enclosed by the dashed circle in FIG. 5 according to the fourth embodiment. [Figure 14] FIG. 14 is a diagram corresponding to the area enclosed by the dashed circle in FIG. 5 according to the fifth embodiment. [Figure 15] FIG. 15 is a diagram corresponding to the area enclosed by the dashed circle in FIG. 5 according to the sixth embodiment. [Figure 16] FIG. 16 is a diagram corresponding to the area enclosed by the broken circle in FIG. 5 according to the seventh embodiment. [Figure 17] FIG. 17 is a diagram corresponding to the area enclosed by the broken circle in FIG. 5 according to the eighth embodiment. [Figure 18] FIG. 18 is a schematic diagram showing the configuration of a main body case according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0007] Several embodiments of the technology disclosed herein will be described below with reference to the drawings. In the following drawings, components and parts that perform the same function are denoted by the same reference numerals. Furthermore, the dimensional relationships (length, width, thickness, etc.) in each drawing do not reflect the actual dimensional relationships. Matters other than those specifically mentioned in this specification that are necessary for implementing the technology disclosed herein (e.g., the general configuration and manufacturing process of an electricity storage device that does not characterize this disclosure) can be understood as design matters of a person skilled in the art based on prior art in the relevant field. The technology disclosed herein can be implemented based on the content disclosed in this specification and common technical knowledge in the relevant field. Furthermore, the following description is not intended to limit the present disclosure to the following forms.

[0008] In this specification, the notation "A to B" indicating a range means "greater than A and less than B." It also encompasses the meanings of "greater than A" and "less than B." In addition, in this specification, the term "electricity storage device" refers to a device that can charge and discharge. 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, a lithium ion secondary battery (hereinafter simply referred to as "battery 100"), which is one embodiment of the electricity storage device disclosed herein, will be described as an example.

[0009] <Battery configuration> FIG. 1 is a perspective view of a battery 100 according to one embodiment. FIG. 2 is a perspective view of the battery 100 of FIG. 1 turned upside down. FIG. 3 shows the internal structure of the battery 100 of FIG. 1. In the following description, the symbols L, R, F, Rr, U, and D in the drawings represent left, right, front, rear, top, and bottom, and the symbols X, Y, and Z in the drawings represent the short side direction of the battery 100, the long side direction perpendicular to the short side direction, and the up-down direction perpendicular to the short side direction and the long side direction, respectively. However, these directions are determined for the convenience of explanation and do not limit the installation mode of the battery 100 in any way.

[0010] As shown in Fig. 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 insulating film 50. Although not shown, the battery 100 further includes an electrolyte. The battery 100 is a lithium ion secondary battery. Preferably, the battery 100 is a lithium ion secondary battery.

[0011] The battery case 10 is a housing that houses the electrode assembly 20, the insulating film 50, and the electrolyte. As shown in FIGS. 1 and 2, the battery case 10 has a flat, bottomed, rectangular parallelepiped (rectangular) outer shape. The material of the battery case 10 may be the same as that conventionally used, and is not particularly limited. The battery case 10 is preferably made of metal, and more preferably made of, for example, aluminum, an aluminum alloy, iron, an iron alloy, or the like.

[0012] 3, the battery case 10 includes a case body 12 having a pair of openings 12h and two lids 14 (specifically, a first lid 14a and a second lid 14b) that close the pair of openings 12h. The battery case 10 is integrated by joining (for example, welding) the lids 14 to the peripheries of the pair of openings 12h of the case body 12. The battery case 10 is hermetically sealed (sealed).

[0013] The case body 12 has a rectangular cylindrical shape and has openings 12h on both sides in its longitudinal direction (corresponding to the Y direction in FIG. 3). In this embodiment, the case body 12 has a rectangular cylindrical shape with rectangular openings 12h on both ends, and has an elongated shape in which the longitudinal direction is sufficiently long relative to the long sides of the openings 12h. On the other hand, the openings 12h have a shape slightly wider than the cross section of the electrode body 20 when cut along the openings 12h. More specifically, as shown in FIG. 1, the case body 12 has a substantially rectangular narrow side 12a, a pair of wide sides 12b extending from the long sides of the narrow side 12a and facing each other, and another narrow side 12a connecting the upper ends of the pair of wide sides 12b. The wide side 12b has a substantially rectangular shape. The narrow side 12a faces the other narrow side 12a. The case body 12 can also be said to have a pair of opposing wide surfaces 12b and a pair of opposing narrow surfaces 12a that are continuous with the pair of wide surfaces 12b. The area of ​​the narrow surfaces 12a is smaller than that of the wide surfaces 12b. The case body 12 is formed, for example, by bending a single metal plate into a cylindrical shape and joining the seams (for example, by welding). Here, a welded joint 12c is located on one narrow surface 12a. A gas exhaust valve 13 is provided on the other narrow surface 12a. Note that in Figure 4 and subsequent figures, the welded joint 12c is omitted for clarity.

[0014] The gas release valve 13 is configured to break when the pressure inside the battery case 10 reaches or exceeds a predetermined value, thereby releasing the gas inside the battery case 10 to the outside. In this embodiment, there is one gas release valve 13, but there may be two or more. In this embodiment, the gas release valve 13 is provided on the narrow surface 12a, but in other embodiments, the gas release valve 13 may be provided on a surface other than the narrow surface 12a, such as the wide surface 12b or the lid 14. The area of ​​the gas release valve 13 is arbitrary.

[0015] 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. In other embodiments, the gas release valve 13 may be, for example, a linear notch (vertical or horizontal only), or may be a conventionally known oval valve (with a notch therein) or a circular valve (with a notch therein). The dimensions of the notch (length, depth) are arbitrary and can be determined appropriately taking into consideration, for example, the pressure resistance of the battery case 10.

[0016] The lid 14 is a plate-like member that seals the opening 12h. The lid 14 has a substantially rectangular shape in a plan view. As shown in FIG. 3, in this embodiment, the lid 14 includes a first lid 14a attached to the opening 12h at one end of the case body 12 in the longitudinal direction (corresponding to the Y direction in FIG. 3) and a second lid 14b attached to the opening 12h at the other end of the case body 12 in the longitudinal direction. The area of ​​the lid 14 is smaller than that of the wide surface 12b. The lid 14 is provided with a liquid inlet 15. The liquid inlet 15 is used to inject electrolyte into the battery case 10 after the lid 14 is assembled to the case body 12. The liquid inlet 15 is sealed with a sealing member 16 after the electrolyte is injected. Note that, although the liquid inlet 15 is provided in the lid 14 in this embodiment, the liquid inlet 15 may be provided in the case body 12 in other embodiments. In addition, in this embodiment, the liquid inlet 15 is provided on a different surface from the gas release valve 13, but in other embodiments, the liquid inlet 15 may be provided on the same surface as the gas release valve 13.

[0017] 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 each fixed to opposing surfaces of the battery case 10 (specifically, the lid body 14). More specifically, the positive electrode terminal 30 is attached to the lid body 14 located on one side in the long side direction Y (the right side in FIGS. 1 and 2). The negative electrode terminal 40 is attached to the lid body 14 located on the other side in the long side direction Y (the left side in FIGS. 1 and 2). In this embodiment, the positive electrode terminal 30 and the negative electrode terminal 40 are provided on the lid body 14, but in other embodiments, the positive electrode terminal 30 and the negative electrode terminal 40 may be provided on the case main body 12. Alternatively, in other embodiments, the positive electrode terminal 30 and the negative electrode terminal 40 may both be provided on one of the lid bodies 14. In addition, in this embodiment, the positive electrode terminal 30 and the negative electrode terminal 40 are provided on a different surface from the gas exhaust valve 13, but in other embodiments, the positive electrode terminal 30 and the negative electrode terminal 40 may be provided on the same surface as the gas exhaust valve 13.

[0018] The positive electrode terminal 30 and the negative electrode terminal 40 are each exposed on the outer surface of the lid 14. Here, the positive electrode terminal 30 and the negative electrode terminal 40 are arranged on an axis that extends in the long side direction Y and passes through the center of the lid 14. However, in other embodiments, the axis may be offset from the center of the lid 14, for example, in the short side direction X. Furthermore, the positive electrode terminal 30 and the negative electrode terminal 40 do not have to be arranged on the axis. For example, one of the positive electrode terminal 30 and the negative electrode terminal 40 may be offset to one side in the short side direction X, and the other may be offset to the other side in the short side direction X.

[0019] 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.

[0020] 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 lid 14 by an insulating member 60 (see Fig. 4).

[0021] The electrode body 20 is housed inside the battery case 10. FIG. 4 is a perspective view of the electrode body 20 attached to the lid 14. As shown in FIG. 4, the electrode body 20 is placed inside the battery case 10 while being covered with an insulating film 50, which will be described later. In this embodiment, one electrode body 20 is housed inside one battery case 10. However, the number of electrode bodies 20 housed inside one battery case 10 is not particularly limited, and in other embodiments, there may be two or more electrode bodies.

[0022] As shown in Fig. 3, the electrode assembly 20 includes a positive electrode 21 and a negative electrode 22. Here, the electrode assembly 20 is a wound electrode assembly. Specifically, 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 interposed therebetween in the longitudinal direction around a winding axis. However, in other embodiments, the electrode assembly 20 may be a laminated electrode assembly formed by stacking a rectangular positive electrode and a rectangular negative electrode in an insulated state.

[0023] Here, the electrode body 20 has a flat outer shape. The electrode body 20 has a pair of curved portions and a pair of flat surfaces connecting the pair of curved portions. The electrode body 20 is housed inside the battery case 10 with its winding axis oriented along the long side direction Y (such a configuration is also referred to as a horizontally wound type). The pair of curved portions of the electrode body 20 face a pair of narrow surfaces 12a of the case body 12, respectively. The pair of flat surfaces of the electrode body 20 face a pair of wide surfaces 12b of the case body 12, respectively. However, the electrode body 20 may also be housed inside the battery case 10 with its winding axis oriented along the vertical direction Z (such a configuration is also referred to as a vertically wound type). The components constituting the electrode body 20 (positive electrode, negative electrode, separator, etc.) may be similar to those of a general secondary battery and are not particularly limited.

[0024] The positive electrode 21 typically includes 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.

[0025] 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, such as 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 is preferably, for example, a composite oxide containing Ni and Li, in which the Ni content in the composite oxide is in the range of 70 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 to 7 mol %.

[0026] The negative electrode 22 typically includes 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.

[0027] 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.

[0028] 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.

[0029] The electrode body 20 has a positive electrode tab 23 and a negative electrode tab 24 extending in opposite directions. The positive electrode tab 23 is a portion extending from the end of the first side (right side) of the electrode body 20 toward the first side. 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. The negative electrode tab 24 is a portion extending from the end of the second side (left side) of the electrode body 20 toward the second side. 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 toward the second side.

[0030] 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 volume ratio of 1 to 99% so that the total ratio is 100%. The supporting salt is, for example, a fluorine-containing lithium salt. The fluorine-containing lithium salt preferably contains lithium hexafluorophosphate (LiPF), lithium bis(fluorosulfonyl)imide (F2LiNO4S2), also known as LiFSI, or a mixture thereof. The concentration of the supporting salt is preferably 0.6 to 1.8 mol per liter of non-aqueous solvent.

[0031] 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-, bag-, or cylindrical shape.

[0032] From the perspective of vehicle installation efficiency, the present inventors have proposed a battery 100, as shown in FIGS. 1 and 2 , that includes a rectangular case body 12 with a large aspect ratio and a long, rectangular cylindrical shape, with a positive terminal 30 and a negative terminal 40 attached to the end cap 14. A thin, elongated cylindrical case body 12 can be used as the case body 12 that houses the electrode assembly 20. The present inventors also considered providing the positive terminal 30 and the negative terminal 40 on the cap 14, thereby minimizing dead space around the cylindrical case body 12 in the longitudinal direction. From this perspective, it is desirable to minimize the difference between the inner diameter of the case body 12 and the electrode assembly 20 in a cross section perpendicular to the longitudinal direction of the cylindrical case body 12. On the other hand, in this battery 100, it is envisioned that the electrode assembly will be inserted from one end of the rectangular cylindrical case body 12, which is open at both ends. In this case, it is desirable to smoothly insert the electrode assembly 20 into the rectangular cylindrical case body 12. In particular, considering future mass production, it is preferable that the battery 100 can be manufactured by machine. In such mechanization, it is important that the case body 12 has a configuration that allows the electrode assembly 20 to be easily inserted.

[0033] Next, a configuration that characterizes the battery 100 according to this embodiment will be described. Here, FIG. 5 is a schematic diagram showing the configuration of the case body according to one embodiment. FIG. 6 is a schematic diagram showing the insertion of an electrode body into the case body according to one embodiment. FIG. 7 is a schematic diagram showing the state in which the electrode body is inserted into the case body of FIG. 5. In the battery 100 according to this embodiment, FIG. 6 illustrates a state in which one end of the electrode body 20 is inserted into an opening 12h at one end of the case body 12. In FIG. 6, the illustration is omitted using a two-dot chain line, except for the portion where one end of the electrode body 20 is inserted into the opening 12h at one end of the case body 12. In addition, in FIG. 7, the negative electrode tab 24 is omitted to make the drawing easier to understand. First, as described above, the battery 100 according to this embodiment includes a rectangular cylindrical case body 12 that is open on both ends in the length direction (corresponding to the Y direction in FIG. 6 ), an electrode assembly 20 housed in the case body 12, a first lid 14a attached to an opening 12h at one end of the case body 12 in the length direction (corresponding to the Y direction in FIG. 6 ), and a second lid 14b attached to an opening 12h at the other end of the case body 12 in the length direction. The case body 12 has a pair of opposing wide surfaces 12b and a pair of opposing narrow surfaces 12a that are continuous with the pair of wide surfaces 12b. As shown in FIG. 5 , the battery 100 according to this embodiment is characterized in that at least one (here, both) of the pair of narrow surfaces 12a has a recess 12a1 extending along the length direction of the case body 12 on the inside of the narrow surface 12a. The recess 12a1 can be said to be a portion that is more recessed in the thickness direction of the narrow face 12a (corresponding to the Z direction in Figure 5) when the inner surface of the narrow face 12a (corresponding to 12a3 in Figure 8) is used as a reference.

[0034] In the battery 100 having such a configuration, as shown in FIG. 6, when the electrode body 20 is inserted into the case body 12 (see FIG. 6), the electrode body 20 does not come into contact with the case body 12 at the recess 12a1 of the narrow surface 12a. 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 is reduced. That is, the resistance in the insertion direction (corresponding to the ID direction in FIG. 6) is suitably reduced. This improves the insertability of the electrode body 20 into the case body 12. Therefore, the productivity of the battery 100 can be suitably improved.

[0035] The number of recesses 12a1 is not particularly limited as long as the effects of the technology disclosed herein are achieved. As shown in FIG. 5, the number of recesses 12a1 may be two, or in other embodiments, three or more, or one. The shape of recess 12a1 is also not particularly limited as long as the effects of the technology disclosed herein are achieved. As shown in FIG. 5, the shape of recess 12a1 (specifically, the shape of recess 12a1 when opening 12h of case body 12 is viewed from the front) may be rectangular, or may have various shapes as shown in the second to eighth embodiments described below. For example, when recesses are formed on both of the pair of narrow surfaces 12a, the shapes of the recesses may be the same or different. In this embodiment, recess 12a1 is formed continuously from one opening 12h to the other opening 12h along the length direction of case body 12. However, in other embodiments, recess 12a1 may be formed intermittently.

[0036] The size of the recess 12a1 is not particularly limited as long as the effects of the technology disclosed herein are achieved. Here, FIG. 8 is an explanatory diagram for explaining the vicinity of the recess in FIG. 5. In FIG. 8, P indicates the thickness of the narrow surface 12a, and Q indicates the depth of the recess 12a1. Q can also be referred to as the distance from the bottom surface 12a6 (bottom) of the recess 12a1 to the inner surface of the narrow surface 12a (corresponding to 12a3 in FIG. 8) in the thickness direction of the narrow surface 12a (corresponding to the Z direction in FIG. 8). The ratio (Q / P) of the depth Q of the recess 12a1 to the thickness P of the narrow surface 12a is, for example, 0.1 or more. From the viewpoint of more suitably reducing contact between the inner surface of the case body 12 and the electrode body 20, it is preferably 0.2 or more, more preferably 0.3 or more, and more preferably 0.4 or more. Although not particularly limited, the depth Q of the recess 12a1 can be, for example, within a range of 0.01 mm to 1 mm. The upper limit of the ratio (Q / P) is, for example, 0.9 or less, and from the viewpoint of suitably ensuring the strength of the case body 12, it is preferably 0.8 or less, 0.7 or less, and more preferably 0.6 or less, 0.5 or less.

[0037] 8, R indicates the length of the narrow surface 12a in the width direction (corresponding to the X direction in FIG. 8), and S indicates the length of the narrow surface 12a of the recess 12a1 in the width direction. The ratio (S / R) of the length S of the narrow surface 12a of the recess 12a1 in the width direction to the length R of the narrow surface 12a in the width direction is, for example, 0.1 or more, and from the viewpoint of more suitably reducing the contact area between the inner surface of the case body 12 and the electrode body 20, it is preferably 0.2 or more, more preferably 0.3 or more, or 0.4 or more. The upper limit of the ratio (S / R) is, for example, 0.9 or less, and from the viewpoint of suitably ensuring the strength of the case body 12, it is preferably 0.8 or less, 0.7 or less, and more preferably 0.6 or less, or 0.5 or less. Although not particularly limited, the length S of the narrow surface 12a of the recess 12a1 in the width direction can be, for example, within the range of 0.01 mm to 1 mm.

[0038] The recess 12a1 may be present on only one of the pair of narrow surfaces 12a, or may be present on both. Meanwhile, in a preferred embodiment, the recess 12a1 is present on both of the pair of narrow surfaces 12a, as shown in Fig. 5. With this configuration, the number of non-contact surfaces between the electrode body 20 and the case body 12 increases, reducing insertion resistance into the case body 12 and thereby more suitably improving the ease of inserting the electrode body 20 into the case body 12.

[0039] The recess 12a1 may be formed at any position on the narrow surface 12a as long as the effects of the technology disclosed herein are achieved. Meanwhile, in a preferred embodiment, as shown in FIG. 8 , when the narrow surface 12a is divided into a pair of end portions 12a2 and a central portion 12a4 along the width direction (corresponding to the X direction in FIG. 8 ), the recess 12a1 is located in the central portion 12a4. With this configuration, the central portion 12a4 is a non-contact portion between the electrode assembly 20 and the case body 12, reducing insertion resistance into the case body 12. Furthermore, the portions other than the central portion 12a4 (i.e., the pair of end portions 12a2) act as guides for the insertion direction of the electrode assembly 20, stabilizing the insertion posture of the electrode assembly 20 and thereby improving ease of insertion of the electrode assembly 20 into the case body 12. In another embodiment, the recess 12a1 may be located in the central portion when the narrow surface 12a is divided into three equal portions along the width direction and divided into a pair of end portions and a central portion. Alternatively, when narrow surface 12a is divided into five equal parts in the width direction into a pair of end portions and a central portion, recess 12a1 may be present in the central portion.Alternatively, when narrow surface 12a is divided into seven equal parts in the width direction into a pair of end portions and a central portion, recess 12a1 may be present in the central portion.

[0040] 8 , the pair of end portions 12a2 have end faces 12a3 on the inside of the narrow faces 12a, and each end face 12a3 is configured to be able to guide the insertion posture of the electrode body 20 when the electrode body 20 is inserted into the case body 12. The end faces 12a3 can also be said to be guide faces that guide the insertion posture of the electrode body 20 into the case body 12. With this configuration, the end faces 12a3 in the width direction of the narrow faces 12a of the case body 12 can serve as guides when the electrode body 20 is inserted into the case body 12, making it easier to insert the electrode body 20 into the case body 12.

[0041] In a preferred embodiment, as shown in Fig. 8, the end faces 12a3 are on the same plane. The distance between the opposing inner surfaces of the pair of narrow faces 12a is constant. Alternatively, the distance (corresponding to P in Fig. 8) of each end face 12a3 from the outer surface 12a5 of the narrow face 12a in the thickness direction (corresponding to the Z direction in Fig. 8) can be said to be equal. With this configuration, the insertion posture of the electrode body 20 into the case body 12 is stable, making it easier to insert the electrode body 20 into the case body 12.

[0042] In a preferred embodiment, as shown in FIG. 6 , the wide surface 12b and the narrow surface 12a are rectangular with long and short sides, and the long sides extend along the insertion direction of the electrode assembly 20 (corresponding to the ID direction in FIG. 6 ). The technology disclosed herein is more effective when the electrode assembly is inserted a long distance, making such a configuration suitable for application of the technology disclosed herein. While not particularly limited, the ratio of the length of the long side to the length of the short side (long side length / short side length) of the wide surface 12b is, for example, 2 or more. From the viewpoint of being more suitable for the above-mentioned application, it is preferably 3 or more, and more preferably 4 or more. The upper limit of the ratio (long side length / short side length) is, for example, 8 or less. From the viewpoint of making the battery 100 easier to fabricate, it is preferably 7 or less, 6 or less, and more preferably 5 or less.

[0043] One advantage of forming the recess 12a1 on the narrow surface 12a of the case body 12 as disclosed herein will now be described. FIG. 9 is an explanatory diagram for explaining the restraint of a battery according to one embodiment. FIG. 10 is an explanatory diagram for explaining the case where the recess is present on the wide surface. Note that the positive electrode tab 23 is omitted from FIG. 10 for clarity. As shown in FIG. 9, the battery 100 is used as a battery pack by being restrained, for example, in the direction of the outline arrow. In this case, the wide surface 12b is the surface on which the restraining force is generated. Furthermore, as shown in FIG. 10, when the recess 12b1 is formed on the wide surface 12b, a region on the electrode body 20 on which the restraining force is generated (corresponding to region A in FIG. 10) and a region on which the restraining force is not generated (corresponding to region B in FIG. 10) may be generated. In this case, the distance between the electrode plates increases in region B, which may hinder the progress of the chemical reaction. Therefore, from the viewpoint of battery performance, etc., it is preferable to form the recess 12a1 on the narrow surface 12a.

[0044] <Battery manufacturing method> Next, a description will be given of an example of a method for manufacturing the battery 100. Note that the following description is not intended to limit the method for manufacturing the battery 100.

[0045] First, a method for manufacturing the case body 12 will be described. First, a single metal plate is prepared. Then, a portion of the metal plate corresponding to the narrow surface 12a is press-molded to form the recess 12a1. Next, the gas release valve 13 is formed at a predetermined position on the metal plate by a conventionally known method. Subsequently, the metal plate with the recess 12a1 and the gas release valve 13 formed therein is bent into a cylindrical shape, and the seams are joined (for example, by laser welding or the like). In this way, the case body 12 is obtained. The recess 12a1 can also be formed by cutting using a milling cutter or the like. Furthermore, in the second to eighth embodiments described later, the recesses have various different shapes, but these shapes can be made different by press molding, cutting using a milling cutter, or the like.

[0046] Next, an electrode assembly 20 manufactured by a conventional method is prepared. Then, 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 body 14a is joined to the negative electrode current collector 42 to form an integrated body. Next, this integrated body is inserted into the case body 12 manufactured as described above. Then, the positive electrode current collector 32 is joined to the positive electrode terminal 30 provided on the second lid body 14b. The case body 12 is joined to the first lid body 14a and the second lid body 14b, respectively. Finally, an electrolyte is injected through the injection hole to obtain the battery 100.

[0047] 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.

[0048] The embodiments of the technology disclosed herein have been described above. However, the above description is merely an example and does not limit the scope of the claims. The technology described in the claims includes various modifications and alterations of the specific examples exemplified in the above description.

[0049] FIG. 11 is a diagram corresponding to the broken-line circle in FIG. 5 according to the second embodiment. In FIG. 11, 112a, 112a1, 112a2, and 112a3 represent a narrow surface, a recess, an end portion, and an end face, respectively. As shown in FIG. 11, in the second embodiment, the shape of the recess 112a1 (more specifically, the shape of the recess 112a1 when the opening of the case body is viewed from the front) is trapezoidal. Note that for the number, size, and formation position of the recess 112a1, the relevant description of the recess 12a1 can be referred to as appropriate.

[0050] FIG. 12 is a diagram corresponding to the broken-line circle in FIG. 5 according to the third embodiment. In FIG. 12, 212a, 212a1, 212a2, and 212a3 represent a narrow surface, a recess, an end portion, and an end face, respectively. As shown in FIG. 12, in the third embodiment, the shape of the recess 212a1 (more specifically, the shape of the recess 112a1 when the opening of the case body is viewed from the front) is an arc shape. Note that, for the number, size, and formation position of the recess 212a1, the relevant description of the recess 12a1 can be referred to as appropriate.

[0051] FIG. 13 is a diagram corresponding to the dashed circle in FIG. 5 according to the fourth embodiment. In FIG. 13, 312a, 312a1, 312a2, and 312a3 represent a narrow surface, a recess, an end portion, and an end face, respectively. As shown in FIG. 13, in the fourth embodiment, the shape of the recess 312a1 (more specifically, the shape of the recess 312a1 when the opening of the case body is viewed from the front) is an inverted arc shape. Note that, for the number, size, and formation position of the recess 312a1, the corresponding description of the recess 12a1 can be referred to as appropriate. Furthermore, in the fourth embodiment, the bottom surface (bottom) of the recess 312a1 can refer to the vertex of the inverted arc.

[0052] FIG. 14 is a diagram corresponding to the broken-line circle in FIG. 5 according to the fifth embodiment. In FIG. 14, 412a, 412a1, 412a2, and 412a3 represent a narrow surface, a recess, an end portion, and an end face, respectively. As shown in FIG. 14, in the fifth embodiment, the shape of the recess 412a1 (more specifically, the shape of the recess 412a1 when the opening of the case body is viewed from the front) is a V-groove shape. Note that, for the number, size, and formation position of the recess 412a1, the corresponding description of the recess 12a1 can be referred to as appropriate.

[0053] FIG. 15 is a diagram corresponding to the dashed circle in FIG. 5 according to the sixth embodiment. In FIG. 15, 512a, 512a1, 512a2, and 512a3 represent a narrow surface, a recess, an end portion, and an end face, respectively. As shown in FIG. 15, in the sixth embodiment, the shape of the recess 512a1 (more specifically, the shape of the recess 512a1 when the opening of the case body is viewed from the front) is stepped. Note that the number, size, and formation position of the recess 512a1 can be determined by referring to the relevant description of the recess 12a1. In addition, in the sixth embodiment, the bottom surface (bottom portion) of the recess 512a1 may refer to the surface of the step closest to the outer surface of the narrow surface 512a.

[0054] FIG. 16 is a diagram corresponding to the dashed circle in FIG. 5 according to the seventh embodiment. In FIG. 16, 612a, 612a1, 612a2, and 612a3 represent a narrow surface, a recess, an end portion, and an end face, respectively. As shown in FIG. 16, in the seventh embodiment, the shape of the recess 612a1 (more specifically, the shape of the recess 612a1 when viewed from the front of the opening of the case body) is stepped. In this embodiment, unlike the sixth embodiment, one of the three steps is inverted relative to the other two steps. Note that for the number, size, and formation position of the recess 612a1, the relevant description of the recess 12a1 can be referred to as appropriate. Furthermore, in the seventh embodiment, the bottom surface (bottom portion) of the recess 612a1 may refer to the surface of the step closest to the inner surface of the narrow surface 612a.

[0055] FIG. 17 is a diagram corresponding to the broken-line circle in FIG. 5 according to the eighth embodiment. In FIG. 17, 712a, 712a1, 712a2, and 712a3 represent a narrow surface, a recess, an end portion, and an end face, respectively. As shown in FIG. 17, in the eighth embodiment, the shape of the recess 712a1 (more specifically, the shape of the recess 712a1 when the opening of the case body is viewed from the front) is an elongated hole. Note that, for the number, size, and formation position of the recess 712a1, the corresponding description of the recess 12a1 can be referred to as appropriate.

[0056] FIG. 18 is a schematic diagram showing the configuration of a case body according to another embodiment. In FIG. 18, 812a, 812a1, 812b, and 812b1 represent a narrow surface, a recess, a wide surface, and a wide surface recess, respectively. As shown in FIG. 18, in the eighth embodiment, at least one (here, both) of the pair of wide surfaces 812b has a wide surface recess 812b1 extending along the length direction of the case body (corresponding to the Y direction in FIG. 18). This configuration increases the number of non-contact surfaces between the electrode assembly 20 and the case body 12, reducing insertion resistance and further improving ease of insertion of the electrode assembly 20 into the case body 12. Note that the number, size, and location of the wide surface recess 812a1 can be referred to by replacing "narrow surface" with "wide surface" in the relevant description of the recess 12a1.

[0057] As described above, specific aspects of the technology disclosed herein include those described in the following sections. Item 1: An electricity storage device comprising: a rectangular cylindrical case body that is open on both longitudinal sides; an electrode body housed in the case body; a first lid body attached to the opening at one longitudinal end of the case body; and a second lid body attached to the opening at the other longitudinal end of the case body, wherein the case body has a pair of opposing wide surfaces and a pair of opposing narrow surfaces that are continuous with the pair of wide surfaces, and a recess that extends along the longitudinal direction of the case body is present on the inside of at least one of the pair of narrow surfaces. Item 2: The electricity storage device according to item 1, wherein the recess is present on both of the pair of narrow surfaces. Item 3: The electricity storage device according to item 1 or 2, wherein when the narrow surface is divided into a pair of ends and a central portion along the width direction, the recess is present in the central portion. Item 4: The energy storage device described in Item 3, wherein the pair of end portions have end faces on the inside of the narrow side, and each end face is configured to be able to guide the insertion posture of the electrode body when the electrode body is inserted into the case body. Item 5: The electricity storage device according to Item 4, wherein the end faces are on the same plane. Item 6: The electricity storage device according to any one of items 1 to 5, wherein the wide surface and the narrow surface are rectangular having long sides and short sides, and the long sides extend along the insertion direction of the electrode assembly. Item 7: The electricity storage device according to any one of items 1 to 6, wherein at least one of the pair of wide surfaces has a wide surface recess extending along the length of the case body. [Explanation of symbols]

[0058] 10 Battery case 12 Case body 12a narrow side 12b wide face 12c Welded joints 12h opening 13 Gas exhaust valve 14 Lid 14a First lid 14b Second cover 15 Liquid injection hole 16 Sealing member 20 Electrode body 21 Positive electrode 22 Negative electrode 23 Positive electrode tab 24 Negative electrode tab 30 Positive terminal 32 Positive electrode current collector 40 Negative terminal 42 Negative electrode current collector 50 insulating film 60 Insulating material 100 batteries

Claims

1. a rectangular cylindrical case body having openings on both sides 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 inner surface of at least one of the pair of narrow surfaces has a recess extending along the length of the case body;

2. The electricity storage device according to claim 1 , wherein the recessed portion is present in both of the pair of narrow surfaces.

3. The electricity storage device according to claim 1 , wherein when the narrow surface is divided into a pair of end portions and a central portion along the width direction, the recessed portion is present in the central portion.

4. 4. The energy storage device according to claim 3, wherein the pair of end portions have end faces on the inside of the narrow side, and each end face is configured to be able to guide the insertion posture of the electrode body when the electrode body is inserted into the case body.

5. The electricity storage device according to claim 4 , wherein the end faces are on the same plane.

6. the wide surface and the narrow surface are rectangular having long sides and short sides, The electricity storage device according to claim 1 , wherein the long sides extend along the insertion direction of the electrode assembly.

7. The electricity storage device according to claim 1 , wherein at least one of the pair of wide surfaces has a wide surface recess extending along the length of the case body.

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