JP2022079875A - Secondary battery - Google Patents

Abstract

To improve heat dissipation of a secondary battery.SOLUTION: A secondary battery 10 includes a battery case 41 in which an electrode body is accommodated. The battery case 41 has a case body 41a having a substantially rectangular parallelepiped square shape opened at one side thereof, and a lid 41b mounted at the opening. At least two plates 81, 82 are joined to the case body 41a. The case body 41a has a substantially rectangular bottom surface portion 61, a pair of wide surface portions 62, 63 rising from the opposite long sides of the bottom surface portion 61, and a pair of narrow surface portions 64,65 rising from the opposite short sides of the bottom surface portion 61. Irregularities 70 are formed on the bottom surface portion 61 and at least one outer surface of the pair of wide surface portions 62,63 and the pair of narrow surface portions 64,65.SELECTED DRAWING: Figure 5

Description

The present invention relates to a secondary battery.

The secondary battery has, for example, a structure in which an electrode body is housed in a battery container. As the battery container, a metal container such as aluminum or stainless steel is used from the viewpoint of achieving both strength and weight reduction. As the battery container, for example, a bottomed square type battery container is manufactured by deep drawing.

Japanese Unexamined Patent Publication No. 2014-130780 describes forming a groove (projection) for forming a passage of a refrigerant leading from a bottom surface to a side surface, arranging an insulating sheet between cells, and the like. In the same publication, it is stated that such a groove can be formed during press molding of a cell container. An air flow path (refrigerant flow path) continuous in the arrangement direction of the plurality of battery cells is formed between the battery module and the upper surface of the tray on which the battery module is installed. In the battery package provided with the battery module, the air introduced into the case from the air introduction port flows into the air flow path and flows from below into the flow path between the battery cells adjacent to each other.

Japanese Unexamined Patent Publication No. 2017-107773 discloses another method for producing a bottomed square battery container. In the method disclosed here, a first member composed of a rectangular bottom surface and a pair of long side surfaces that are connected to the bottom surface and are bent from the bottom surface and face each other is one first member. Formed from a flat plate. The second flat plates constituting each of the pair of short side surfaces facing each other are welded to the first member from one direction. A third flat plate facing the rectangular bottom surface is further welded. According to this method, the material yield is said to be improved.

Japanese Unexamined Patent Publication No. 2014-130780 Japanese Unexamined Patent Publication No. 2017-107773

By the way, in the battery module, a plurality of secondary batteries are arranged and stacked so that their wide surfaces face each other. Of the multiple secondary batteries arranged side by side, the battery placed in the middle tends to retain heat. On the other hand, the present inventor is considering cooling through the bottom surface and the narrow surface of a plurality of arranged secondary batteries. The present inventor wants to improve the heat dissipation from the bottom surface and the narrow surface of the secondary battery. Further, a refrigerant flow path may be formed on a wide surface which is a facing surface of the secondary battery, and it may be desired to improve heat dissipation. On the other hand, when the battery case is formed by deep drawing, it is difficult to process the bottom surface, the narrow surface, and the wide surface in a complicated manner. In addition, it is difficult to improve the heat dissipation of the bottom surface, narrow surface, and wide surface only by combining and joining flat plates.

The secondary battery disclosed here includes an electrode body and a battery case containing the electrode body. The battery case has a case body having a substantially rectangular parallelepiped rectangular shape with one side open, and a lid attached to the opening. At least two or more plates are joined to the case body. The case body has a substantially rectangular bottom surface portion, a pair of wide surface portions rising from the opposite long sides of the bottom surface portion, and a pair of narrow surface portions rising from the opposite short sides of the bottom surface portion. Concavities and convexities are formed on at least one outer surface of the bottom surface portion, the pair of wide surface portions, and the pair of narrow surface portions. According to such a secondary battery, at least two or more plate materials are joined to the case body. Therefore, the degree of freedom of the unevenness provided is high. In addition, the heat dissipation of the outer surface on which the unevenness is formed is improved.

Here, the unevenness may be a plurality of streaks arranged in a predetermined pattern. The unevenness may be a plurality of dots arranged in a predetermined pattern. The portion where the unevenness is formed may be set to a portion other than the portion where the two or more plate materials constituting the case main body are joined. Another plate having irregularities formed on at least one outer surface of the bottom surface portion, the pair of wide surface portions, and the pair of narrow surface portions may be laminated.

The case main body may be a member in which a plate material including a bottom surface portion and a pair of narrow surface portions and two plate materials constituting the pair of wide surface portions are joined. The case main body may be a member in which a plate material including a bottom surface portion and a pair of narrow surface portions and two plate materials constituting the pair of wide surface portions are joined. The case main body may have two wide surfaces one by one and may be provided with two plate materials joined along a joint portion set for a bottom surface portion and a pair of narrow surface portions.

The unevenness may be formed by press molding or cutting. Another plate having irregularities formed on at least one outer surface of the bottom surface portion, the pair of wide surface portions, and the pair of narrow surface portions may be laminated.

FIG. 1 is a partial cross-sectional view of the secondary battery 10. FIG. 2 is a perspective view of the case body 41a. FIG. 3 is a schematic view schematically showing a configuration example of a plate material to be joined to the case body 41a. FIG. 4 is a schematic view schematically showing a configuration example of a plate material to be joined to the case body 41a. FIG. 5 is a schematic diagram of the secondary battery 10 according to another embodiment. FIG. 6 is a partial cross-sectional view of the secondary battery 10 according to another embodiment. FIG. 7 is a perspective view schematically showing the assembled battery 200. FIG. 8 is a perspective view showing the secondary battery 10 according to another embodiment.

Hereinafter, an embodiment of the secondary battery disclosed here will be described. The embodiments described herein are, of course, not intended to specifically limit the invention. The invention is not limited to the embodiments described herein, unless otherwise noted. Each drawing is drawn schematically and does not necessarily reflect the real thing. Further, members / parts having the same action are appropriately designated by the same reference numerals, and duplicate description will be omitted.

<< Secondary battery 10 >>
FIG. 1 is a partial cross-sectional view of the secondary battery 10. In FIG. 1, a state in which the inside is exposed is drawn along a wide surface on one side of a substantially rectangular parallelepiped battery case 41. The secondary battery 10 shown in FIG. 1 is a so-called sealed battery. Here, a battery and a method for manufacturing the battery will be described by taking such a sealed battery as an example. As shown in FIG. 1, the secondary battery 10 includes an electrode body 20, a battery case 41, terminals 42, 43, and insulating resins 44, 45.

<Electrode body 20>
The electrode body 20 is housed in the battery case 41 in a state of being covered with an insulating film (not shown) or the like. The electrode body 20 includes a positive electrode sheet 21 as a positive electrode element, a negative electrode sheet 22 as a negative electrode element, and separator sheets 31 and 32 as separators. The positive electrode sheet 21, the first separator sheet 31, the negative electrode sheet 22, and the second separator sheet 32 are long strip-shaped members, respectively.

The positive electrode sheet 21 is a positive electrode current collector foil 21a (for example, an aluminum foil) having a predetermined width and thickness, except for an unformed portion 21a1 set to a constant width at one end in the width direction. A positive electrode active material layer 21b containing a positive electrode active material is formed on both surfaces. The positive electrode active material is, for example, a material that can release lithium ions during charging and absorb lithium ions during discharging, such as a lithium transition metal composite material in a lithium ion secondary battery. Various positive electrode active materials have been generally proposed in addition to the lithium transition metal composite material, and are not particularly limited.

The negative electrode sheet 22 is formed on a negative electrode current collector foil 22a (here, a copper foil) having a predetermined width and thickness, except for an unformed portion 22a1 set to a constant width on one edge in the width direction. The negative electrode active material layer 22b containing the negative electrode active material is formed on both surfaces. The negative electrode active material is, for example, in a lithium ion secondary battery, a material that can absorb lithium ions during charging and release the stored lithium ions during charging, such as natural graphite. Various negative electrode active materials have been generally proposed in addition to natural graphite, and are not particularly limited.

For the separator sheets 31 and 32, for example, a porous resin sheet through which an electrolyte having a required heat resistance can pass is used. Various separator sheets 31 and 32 have also been proposed and are not particularly limited.

Here, the width of the negative electrode active material layer 22b is formed wider than, for example, the positive electrode active material layer 21b. The width of the separator sheets 31 and 32 is wider than that of the negative electrode active material layer 22b. The unformed portion 21a1 of the positive electrode current collecting foil 21a and the unformed portion 22a1 of the negative electrode current collecting foil 22a are directed to opposite sides in the width direction. Further, the positive electrode sheet 21, the first separator sheet 31, the negative electrode sheet 22, and the second separator sheet 32 are oriented in the length direction, respectively, and are stacked and wound in order. The negative electrode active material layer 22b covers the positive electrode active material layer 21b with the separator sheets 31 and 32 interposed therebetween. The negative electrode active material layer 22b is covered with separator sheets 31 and 32. The unformed portion 21a1 of the positive electrode current collector foil 21a protrudes from one side of the separator sheets 31 and 32 in the width direction. The unformed portion 22a1 of the negative electrode current collector foil 22a protrudes from the separator sheets 31 and 32 on the opposite side in the width direction.

As shown in FIG. 1, the above-mentioned electrode body 20 is in a flat state along a plane including a winding shaft so that it can be accommodated in the case body 41a of the battery case 41. Along the winding axis of the electrode body 20, the unformed portion 21a1 of the positive electrode current collecting foil 21a is arranged on one side, and the unformed portion 22a1 of the negative electrode current collecting foil 22a is arranged on the opposite side.

<Battery case 41>
As shown in FIG. 1, the battery case 41 houses the electrode body 20. The battery case 41 has a case body 41a having a substantially rectangular parallelepiped square shape with one side surface open, and a lid 41b attached to the opening. In this embodiment, the lid 41b is attached with a terminal 42 on the positive electrode side and a terminal 43 on the negative electrode side. The terminals 42 and 43 include internal terminals 42a and 43a and external terminals 42b and 43b. The internal terminals 42a and 43a are attached to the inside of the lid 41b via the gasket 44, respectively. The external terminals 42b and 43b are attached to the outside of the lid 41b via the insulator 45, respectively. The internal terminals 42a and 43a extend inside the case body 41a, respectively. The internal terminal 42a is connected to the unformed portion 21a1 of the positive electrode current collector foil 21a. The internal terminal 43a is connected to the unformed portion 22a1 of the negative electrode current collector foil 22a. The internal terminal 42a and the external terminal 42b of the terminal 42 on the positive electrode side, and the internal terminal 43a and the external terminal 43b of the terminal 43 on the negative electrode side are connected through the lid 41b, respectively. The gasket 44 and the insulator 45 ensure the insulation from the lid 41b and the airtightness of the portion penetrating the lid 41b, respectively. The terminals 42, 43, the gasket 44, and the insulator 45 are not limited to the forms disclosed here unless otherwise specified. The structures of the terminals 42, 43, the gasket 44, and the insulator 45 can be appropriately changed. The gasket 44 and the insulator 45 may be configured as an integral insulating resin.

<Case body 41a>
FIG. 2 is a perspective view of the case body 41a. As shown in FIGS. 1 and 2, the case body 41a has a substantially rectangular parallelepiped rectangular shape with one side surface open. The case body 41a has a substantially rectangular bottom surface portion 61, a pair of wide surface portions 62, 63, and a pair of narrow surface portions 64, 65. The pair of wide surface portions 62 and 63 rise from the long side of the bottom surface portion 61, respectively. The pair of narrow surface portions 64 and 65 rise from the short side of the bottom surface portion 61, respectively.

<Cover 41b>
The lid 41b has the long sides of the pair of wide surface portions 62 and 63 and the short sides of the pair of narrow surface portions 64 and 65 after the first plate material 81, the second plate material 82 and the third plate material 83 are joined. It is attached to the opening 41a1 of the case body 41a surrounded by. Then, the peripheral edge portion of the lid 41b is joined to the edge of the opening 41a1 of the case body 41a. Such joining may be, for example, continuous welding with no gaps. Such welding can be achieved, for example, by laser welding.

As shown in FIG. 1, the unformed portion 21a1 of the positive electrode current collecting foil 21a and the unformed portion 22a1 of the negative electrode current collecting foil 22a are attached to both sides of the lid 41b in the longitudinal direction. It is attached to the internal terminals 42a and 43a. The electrode body 20 is housed in the battery case 41 in a state of being attached to the internal terminals 42a and 43a attached to the lid 41b. In addition, here, the winding type electrode body 20 is exemplified. The structure of the electrode body 20 is not limited to such a form. The structure of the electrode body 20 may be, for example, a laminated structure in which a positive electrode sheet and a negative electrode sheet are alternately laminated with a separator sheet interposed therebetween. Further, a plurality of electrode bodies 20 may be housed in the battery case 41.

<Structure of case body 41a>
In the secondary battery 10 disclosed here, at least two or more plate materials are joined to the case body 41a.

FIG. 3 is a schematic view schematically showing a configuration example of a plate material to be joined to the case body 41a. As shown in FIG. 3, the case body 41a has a first plate material 81 having a bottom surface portion 61 and a pair of wide surface portions 62, 63, a second plate material 82 constituting the narrow surface portion 64, and a width thereof. A third plate member 83 constituting the narrow surface portion 65 is provided. In this embodiment, the first plate member 81 is bent along the long side of the bottom surface portion 61. By being bent, a pair of wide surface portions 62, 63 rising from the long side of the first plate member 81 are provided. The second plate material 82 and the third plate material 83 each have a rectangular shape having sides corresponding to the short sides of the bottom surface portion 61 and the short sides of the pair of wide surface portions 62 and 63, respectively.

The edge of the second plate material 82 is joined to the short side of the bottom surface portion 61 and the short side of the pair of wide surface portions 62, 63 on one side surface of the first plate material 81. The edge of the third plate member 83 is joined to the short side of the bottom surface portion 61 and the short side of the pair of wide surface portions 62, 63 on the other side surface of the first plate material 81. Such joining may be, for example, continuous welding with no gaps. Such welding can be achieved, for example, by laser welding. In FIG. 3, the arrows L1 and L2 represent the loci of the laser during welding, respectively.

The plate members constituting the case body 41a may be joined by, for example, solid phase joining. As the solid phase bonding, for example, ultrasonic bonding may be adopted. In ultrasonic bonding, two plates constituting the case body 41a are overlapped inside and outside at a boundary portion, sandwiched between a horn and an anvil, and the horn is vibrated. As a result, the two stacked plates are heated and softened in a solid phase (solid) state without melting, and further pressurized to give plastic deformation to join them. In addition to ultrasonic bonding, cold pressure welding, hot pressure welding, friction welding and the like can be adopted as the bonding method by solid phase bonding. Further, for the joining of two or more plate materials constituting the case body 41a, solid phase joining and welding may be appropriately used.

FIG. 4 is a schematic view schematically showing a configuration example of a plate material to be joined to the case body 41a. In the form shown in FIG. 4, the case body 41a has a first plate material 81 having a bottom surface portion 61 and a pair of narrow surface portions 64, 65, a second plate material 82 constituting the wide surface portion 62, and a wide surface portion. It includes a third plate member 83 constituting 63. In this embodiment, the first plate member 81 is bent along the short side of the bottom surface portion 61. By being bent, a pair of narrow surface portions 64, 65 rising from the short side of the bottom surface portion 61 are provided. The second plate material 82 and the third plate material 83 each have a rectangular shape having sides corresponding to the long sides of the bottom surface portion 61 and the long sides of the pair of narrow surface portions 64 and 65, respectively.

The edge of the second plate material 82 is joined to the long side of the bottom surface portion 61 and the long side of the pair of narrow surface portions 64, 65 on one side surface of the first plate material 81. The edge of the third plate member 83 is joined to the long side of the bottom surface portion 61 and the long side of the pair of narrow surface portions 64, 65 on the other side surface of the first plate material 81. Such joining may be, for example, continuous welding with no gaps. Such welding can be achieved, for example, by laser welding. In FIG. 4, the arrows L1 and L2 represent the loci of the laser during welding, respectively.

FIG. 5 is a schematic diagram of the secondary battery 10 according to another embodiment. FIG. 5 schematically shows another form of the plate material to be joined to the case body 41a. In the form shown in FIG. 5, the case body 41a has one wide surface portion 62, 63 each, and is joined along the joint portion set for the bottom surface portion 61 and the pair of narrow surface portions 64, 65. The two plate members 81 and 82 are provided. In the form shown in FIG. 5, the boundary K1 is set at the center of the bottom surface portion 61 and the pair of narrow surface portions 64, 65 in the short side direction at the portion where the two plate members 81 and 82 are joined. The two plate members 81 and 82 are joined along the boundary K1. Such joining may be by continuous welding without gaps, for example laser welding may be employed. The plate materials 81 and 82 are, for example, cut out from a plate-shaped material into a predetermined shape, and are press-molded so that the portions forming the bottom surface portion 61 and the pair of narrow surface portions 64 and 65 rise from the wide surface portions 62 and 63, respectively. It is good. In such a form, the portion forming the bottom surface portion 61 and the pair of narrow surface portions 64, 65 is extended. Therefore, it is not suitable as a portion for forming the unevenness 70 according to the press working. On the other hand, on the portions of the plate materials 81 and 82 that are the wide surface portions 62 and 63, appropriate unevenness 70 may be formed according to the press working.

As described above, the case body 41a includes a substantially rectangular bottom surface portion 61, a pair of wide surface portions 62, 63, and a pair of narrow surface portions 64, 65. The case body 41a is formed by joining two or more plate materials separated along a boundary between a bottom surface portion 61, a pair of wide surface portions 62, 63, and a pair of narrow surface portions 64, 65. The boundary for dividing the case body 41a into two or more plate materials can be set in various ways. Then, it is preferable that two or more plate materials can be developed into one plate material. In this case, a plate material that is a material constituting two or more plate materials can be prepared, for example, by punching one flat plate.

Concavo-convex 70 is formed on at least one outer surface of the bottom surface 61 of the case body 41a, the pair of wide surface portions 62, 63, and the pair of narrow surface portions 64, 65. For example, in the form shown in FIG. 1, the unevenness 70 is formed on the bottom surface portion 61. The unevenness 70 may be formed not only on the bottom surface portion 61 but also on the pair of wide surface portions 62 and 63 and the pair of narrow surface portions 64 and 65. The unevenness 70 can be formed by, for example, pressing. It can be formed by pressing the surface on which the unevenness 70 is formed before the first plate member 81, the second plate material 82, and the third plate material 83 are joined. Therefore, it is possible to realize a shape in which the case body 41a has a significantly higher degree of freedom than when it is molded by deep drawing.

The unevenness 70 may be a plurality of streaks arranged in a predetermined pattern. The streak-like unevenness 70 may be raised on the outer surface. Further, the streak-like unevenness 70 may be recessed on the outer surface. For example, the unevenness 70 may be a plurality of ridges extending along the short side direction of the bottom surface portion 61. Further, the unevenness may be a plurality of ridges extending along the long side direction of the bottom surface portion 61. Further, the unevenness 70 may have streaky ridges along a grid intersecting the long side direction and the short side direction of the bottom surface portion 61. Further, the grid-like ridges may intersect diagonally with respect to the long side direction and the short side direction of the bottom surface portion 61. Further, the unevenness 70 may have a streak-like ridge extending in a zigzag manner on the bottom surface portion 61. In the streak pattern, it is also possible to form a flow path through which the refrigerant passes along the recess on the surface on which the unevenness 70 is formed. Further, the unevenness 70 may be in the shape of a plurality of dots arranged in a predetermined pattern. In the plurality of dot-shaped patterns, protrusions may be provided on the outer surface, or recesses may be provided on the outer surface. According to the plurality of dot-shaped patterns, the rigidity of the surface on which the unevenness 70 is formed can be improved.

In FIG. 1, the unevenness of the bottom surface portion 61 is formed so that the inner side surface of the case body 41a is deformed. The unevenness formed on the case body 41a is not limited to such a form. For example, the unevenness may be formed on the outer surface so that the inner surface is not deformed. For example, FIG. 6 is a partial cross-sectional view of the secondary battery 10 according to another embodiment. FIG. 6 shows a form in which unevenness is formed on the bottom surface portion 61 of the case body 41a. Here, the case body 41a of the secondary battery 10 may be made of aluminum or an aluminum alloy. Aluminum is highly malleable. Therefore, as shown in FIG. 6, it is possible to press-mold the inner side surface of the bottom surface portion 61 flatly so that the unevenness 70 is formed only on the outer surface surface. In this case, the inner surface of the bottom surface portion 61 can be kept flat.

Here, it is exemplified that the unevenness 70 is provided on the outer surface of the bottom surface portion 61. Since the unevenness 70 is provided on the outer surface of the bottom surface portion 61, the surface area of the bottom surface portion 61 is increased. Therefore, even when the secondary battery 10 generates heat, it becomes easy to dissipate heat from the bottom surface portion 61. Further, the portion where the unevenness 70 is formed on the case body 41a is not limited to the outer surface of the bottom surface portion 61. For example, the unevenness 70 may be formed on the pair of wide surface portions 62, 63 and the pair of narrow surface portions 64, 65.

FIG. 7 is a perspective view schematically showing the assembled battery 200. The assembled battery 200 includes a plurality of secondary batteries 10 and a plurality of spacers 90. Further, the assembled battery 200 is provided with a restraining mechanism. Specifically, for example, the assembled battery 200 includes a pair of end plates 92A and 92B, a restraint band 94, and a plurality of screws 96, as shown in the figure. The pair of end plates 92A and 92B are arranged at both ends of the assembled battery 200 in the arrangement direction of the secondary battery 10. The restraint band 94 is bridged over a pair of end plates 92A and 92B, and is attached to the pair of end plates 92A and 92B by a screw 96. The spacer 90 is sandwiched between two adjacent secondary batteries 10. Further, an end spacer 98 is arranged between the secondary battery 10 and the end plate 92A and between the secondary battery 10 and the end plate 92B, respectively. The terminal 42 on the positive electrode side and the terminal 43 on the negative electrode side of the secondary battery 10 constituting the assembled battery 200 are electrically connected by a bus bar 91. As a result, the secondary batteries 10 constituting the assembled battery 200 are electrically connected in series in order. However, the shape, size, number, arrangement, connection method, etc. of the secondary batteries 10 constituting the assembled battery 200 are not limited to the embodiments disclosed herein, and can be appropriately changed.

In such an assembled battery 200, a plurality of secondary batteries 10 are stacked in order with the wide surface portions 62, 63 (see FIG. 1) facing each other. In this case, the bottom surface portion 61 and the pair of narrow surface portions 64, 65 are exposed to the outside. Therefore, if the unevenness 70 (see FIG. 1) is formed on the bottom surface portion 61 or the pair of narrow surface portions 64, 65, the surface area of the bottom surface portion 61 or the pair of narrow surface portions 64, 65 increases. Then, in the pack case accommodating the assembled battery, it is preferable that a heat path such as a refrigerant is provided along the surface of the secondary battery 10 on which the unevenness 70 is formed. In this case, when the secondary battery 10 generates heat, heat is smoothly dissipated from the bottom surface portion 61 having an increased surface area and the pair of narrow surface portions 64, 65.

Further, the secondary battery 10 may have unevenness 70 (see FIG. 5) formed on the wide surface portions 62 and 63. For example, the wide surface portions 62, 63 can be surfaces facing each other in the assembled battery. As shown in FIG. 7, a spacer 90 may be sandwiched between the secondary batteries 10. At that time, a passage for the refrigerant may be formed between the spacer 90 and the wide surface portions 62 and 63. For example, a refrigerant passage may be formed from the bottom of the assembled battery 200 so as to pass between the secondary battery 10 and the spacer 90. In this case, as the unevenness 70, it is preferable that the wide surface portions 62 and 63 are formed with streaky ridges from the bottom surface portion 61 side toward the lid 41b side. In this case, a passage of the refrigerant leading upward from the bottom surface portion 61 is formed between the secondary battery 10 and the spacer 90 along the streaky swelling of the unevenness 70. In this case, efficient heat dissipation from the wide surface portions 62 and 63 can be expected. Further, the unevenness 70 formed on the wide surface portions 62 and 63 is not limited to such a form. Further, the unevenness 70 formed on the wide surface portions 62, 63 may be in the shape of a streak or a dot shape along the direction in which the pair of narrow surface portions 64, 65 face each other. Further, the unevenness 70 formed on the pair of wide surface portions 62, 63 may have a function of positioning the facing spacer 90.

Further, it is said that the portion where the unevenness 70 is formed is set to the portion excluding the portion where the two or more plate materials 81, 82, 83 (see FIGS. 3 to 5) constituting the case main body 41a are joined. good. In this case, it is preferable that the range in which the unevenness 70 is formed is limited so that the portion to be joined is not deformed when the case body 41a is created.

For example, in the form shown in FIGS. 3 and 4, the battery case 41 is formed by being joined along the side of the case main body 41a made of a rectangular parallelepiped. In the form shown in FIG. 1, unevenness 70 is formed on the bottom surface portion 61. In this case, the bottom surface portion 61 has unevenness 70 so that the portion corresponding to the side of the bottom surface portion 61 corresponding to the boundary between the bottom surface portion 61, the pair of wide surface portions 62, 63 and the pair of narrow surface portions 64, 65 is not deformed. It is preferable that the range in which is formed is set. As a result, the plate material constituting the bottom surface portion 61 can be accurately joined to the plate material constituting the pair of wide surface portions 62, 63 and the pair of narrow surface portions 64, 65.

Further, when the unevenness 70 is formed on the pair of wide surface portions 62, 63, the width is wide so that the side joined at the boundary between the bottom surface portion 61 and the adjacent narrow surface portions 64, 65 is not deformed. It is preferable that the range in which the unevenness 70 is formed is set on the surface portions 62 and 63. When the unevenness 70 is formed on the pair of narrow surface portions 64, 65, the narrow surface portion is provided so that the side joined at the boundary between the bottom surface portion 61 and the adjacent wide surface portions 62, 63 is not deformed. It is preferable that the range in which the unevenness 70 is formed is set in 64 and 65.

Even in the form shown in FIG. 5, it is preferable that the portion where the unevenness 70 is formed is set to the portion excluding the portion where the two plate members 81 and 82 constituting the case main body 41a are joined. That is, the two plates 81 and 82 are joined so that the boundary K1 is not deformed at the center in the short side direction between the bottom surface portion 61 and the pair of narrow surface portions 64 and 65 to which the two plate materials 81 and 82 are joined. It is preferable that the range in which the unevenness 70 is formed is set. It should be noted that this is not always the case when the portions where the two plate members 81 and 82 are joined can be molded so as to match with each other with high accuracy.

As described above, the unevenness 70 provided on the case body 41a may be formed by press molding. Further, the unevenness 70 provided on the case body 41a may be formed by cutting. FIG. 8 is a perspective view showing the secondary battery 10 according to another embodiment. In the form shown in FIG. 8, another plate 72 having an uneven surface 70 formed on at least one outer surface of the bottom surface portion 61, the pair of wide surface portions 62, 63, and the pair of narrow surface portions 64, 65 is bonded to each other. Has been done. The plates 72 may be appropriately joined. In this way, the plate 72 on which the unevenness 70 is formed may be joined to at least one outer surface of the bottom surface portion 61, the pair of wide surface portions 62, 63, and the pair of narrow surface portions 64, 65. For joining the plates 72, welding such as solid phase welding or laser welding can be appropriately adopted. Further, here, it is exemplified that the plate material constituting the case main body 41a is subjected to additional processing to provide the unevenness 70. The method for manufacturing the plate material constituting the case body 41a is not limited. For example, a plate on which the unevenness 70 is processed in advance may be prepared and molded into a plate material constituting the case body 41a.

Although various forms have been described above, according to the secondary battery 10 proposed here, the case main body 41a has a bottom surface portion 61, a pair of wide surface portions 62, 63, and a pair of narrow surface portions 64, 65. Concavities and convexities 70 are formed on at least one of the outer surfaces. Here, at least two or more plate materials are joined to the case body 41a. From the viewpoint of ease of manufacture, the unevenness 70 is preferably provided before the plate materials constituting the case body 41a are joined. The unevenness 70 is provided, for example, by pressing, cutting, or joining another plate provided with the unevenness 70. In this case, the plate material constituting the case main body 41a may be processed to provide the unevenness 70 in advance, or may be additionally processed to provide the unevenness 70. When configured in this way, the degree of freedom of the unevenness 70 provided on the case body 41a is high. The surface area of the outer surface on which the unevenness 70 is formed becomes large. If the outer surface of the case body 41a is provided with the unevenness 70, heat can be easily dissipated from the outer surface. For example, the secondary battery 10 is easily cooled by applying the refrigerant to the outer surface of the case body 41a provided with the unevenness 70. Further, on the outer surface on which the unevenness 70 is formed, the rigidity is improved as compared with the case where the unevenness 70 is not formed. For example, the rigidity of the case body 41a can be increased by providing the unevenness 70 at the required position in the case body 41a.

The secondary batteries disclosed here have been described in various ways. Unless otherwise specified, the battery embodiments mentioned here do not limit the present invention. In addition, the batteries disclosed herein can be variously modified, and each component and each process referred to here can be appropriately omitted or combined as appropriate, as long as no particular problem arises.

10 Secondary battery 20 Electrode body 21 Positive electrode sheet 21a Positive electrode current collector foil 21a1 Unformed portion 21b Positive electrode active material layer 22 Negative electrode sheet 22a Negative electrode collector foil 22a1 Unformed portion 22b Negative electrode active material layer 31, 32 Separator sheet 41 Battery case 41a Case body 41a1 Opening 41b Lid 42, 43 Terminal 42a, 43a Internal terminal 42b, 43b External terminal 44 Gasket (insulating resin)
45 Insulator (insulating resin)
61 Bottom part 62, 63 Wide surface part 64, 65 Narrow surface part 70 Concavo-convex 72 Another plate on which unevenness 70 is formed 81 1st plate material 82 2nd plate material 83 3rd plate material 90 Spacer 91 Bus bar 92A, 92B End plate 94 Restraint band 96 screw 98 end spacer 200 set battery K1 boundary L1, L2 laser trajectory

Claims (10)

With the electrode body,
A battery case containing the electrode body is provided.
The battery case is
A case body with a rectangular parallelepiped square shape with one side open,
It has a lid attached to the opening and has
At least two or more plate materials are joined to the case body, and the case body is formed.
The bottom of the rectangle and
A pair of wide surface portions rising from the opposite long sides of the bottom surface portion,
It has a pair of narrow surface portions rising from the opposite short sides of the bottom surface portion, and has a pair of narrow surface portions.
Concavities and convexities are formed on at least one outer surface of the bottom surface portion, the pair of wide surface portions, and the pair of narrow surface portions.
Secondary battery. The secondary battery according to claim 1, wherein the unevenness is a plurality of streaks arranged in a predetermined pattern. The secondary battery according to claim 1, wherein the unevenness is a plurality of dots arranged in a predetermined pattern. The portion where the unevenness is formed is described in any one of claims 1 to 3, which is set in a portion excluding a portion where the two or more plate materials constituting the case body are joined. Secondary battery. Any one of claims 1 to 4, wherein another plate having irregularities formed on at least one outer surface of the bottom surface portion, the pair of wide surface portions, and the pair of narrow surface portions is laminated. The secondary battery described in. The case body is any one of claims 1 to 5, wherein the case main body is a member in which a plate material including the bottom surface portion and a pair of narrow surface portions and two plate materials constituting the pair of wide surface portions are joined. The secondary battery described in the section. The case body is any one of claims 1 to 5, wherein the case main body is a member in which a plate material including the bottom surface portion and the pair of narrow surface portions and two plate materials constituting the pair of wide surface portions are joined. The secondary battery described in paragraph 1. Claims 1 to 5 include the case main body having one wide surface and two plate members joined along a joint portion set for the bottom surface portion and a pair of narrow surface portions. The secondary battery described in any one of the above items. The secondary battery according to any one of claims 1 to 8, wherein the unevenness is formed by press molding or cutting. One of claims 1 to 8, wherein another plate having irregularities formed on at least one outer surface of the bottom surface portion, the pair of wide surface portions, and the pair of narrow surface portions is laminated. The secondary battery described in.

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