JP6592913B2 - Power storage element and power storage device - Google Patents

Description

  The technology described in this specification relates to a power storage element and a power storage device.

  In recent years, there are increasing opportunities to connect and use a plurality of batteries, which are examples of power storage elements, as power sources for electric vehicles and industrial power supplies, and it is desired to increase the capacity of the batteries. A plurality of batteries are used in a storage box or restrained. At this time, adjacent batteries or peripheral members such as batteries and inter-battery spacers are arranged so as not to interfere with each other.

  Conventionally, for example, a battery described in JP 2000-090893 A is known as a storage element. This power storage element (battery) includes a battery case main body that houses a power storage element (power generation element) and a battery lid. The battery lid has an upright wall (welded portion) that rises upward at the peripheral edge of the oval plate shape. The battery lid is fitted to the inside of the battery case main body, and the standing wall formed at the edge portion overlaps the inner side of the upper end opening of the battery case main body. And the battery case is formed by joining the upper end opening part of a battery case main body, and the standing wall of a battery cover by welding.

JP 2000-090893 A

  In the power storage device, the entire battery lid is fitted inside the battery case body. Specifically, the battery cover is fitted inside the battery case so that the standing wall overlaps the inside of the upper end opening of the battery case. Therefore, the main surface of the battery lid is lowered by the height of the standing wall, and the internal volume of the battery case body is reduced. Therefore, the power storage element accommodated in the battery case main body becomes small, and the internal space of the case of the power storage element cannot be effectively used. Moreover, although the state after welding is not shown in detail in the above-mentioned patent document, the welded portion may swell relative to the original outer shape. For this reason, when a bulge protrudes in the side surface direction of the battery case, there is a risk of interfering with a battery or a peripheral member adjacent in the side surface direction.

  An object of the technology described in the present specification is to provide a power storage element that can suppress interference with other members while effectively utilizing the internal space of the case.

  A power storage element disclosed in the present specification has a cylindrical shape, a case having an opening at at least one end, a cover plate that closes the opening of the case, and a power storage element housed in the case And the case includes a main body portion and an opening end portion that is an end portion on the opening portion side, and the cover plate is disposed so that an outer peripheral edge portion overlaps an end surface of the opening end portion. The outer end surface of the opening end is reduced in diameter toward the inside of the case from the outer surface of the main body, and the inner surface of the opening end is inward of the case and the inner surface of the main body. The diameter is smaller than that.

  According to the technology described in the present specification, an object is to provide a power storage element that can suppress interference with other members while effectively utilizing the internal space of the case.

1 is an exploded perspective view of a battery according to Embodiment 1. FIG. Top view of the battery Schematic diagram of storage element AA line sectional view of FIG. BB sectional view of FIG. Perspective view of negative electrode current collector The figure which expanded the C section of FIG. The figure which expanded D section of Drawing 4 Cross-sectional view of case end (shows comparative example) FIG. 7 is a partially enlarged view (showing the opening end) The figure which shows the numerical example of the board thickness of the case and the size of the step of the opening end Top view of power storage device of embodiment 2 Perspective view of power storage element (shows another embodiment) Sectional view of the upper lid plate (shows another embodiment)

  An outline of the electricity storage device of this embodiment will be described. The power storage element has a cylindrical shape, and includes a case having an opening at at least one end, a cover plate that closes the opening of the case, and a power storage element housed in the case, The case has a main body portion and an opening end portion that is an end portion on the opening portion side, and the cover plate is arranged with an outer peripheral edge portion being overlapped on an end surface of the opening end portion, and the opening The outer surface of the end portion is reduced in diameter toward the inside of the case from the outer surface of the main body portion, and the inner surface of the opening end portion is reduced in diameter toward the inner side of the case from the inner surface of the main body portion. Yes.

  According to the electricity storage device of the present embodiment, the outer peripheral edge portion of the lid plate is arranged so as to overlap the end surface of the opening end portion of the case, so that the entire lid plate is fitted in the opening end portion of the case. The inner volume of the case is increased. Therefore, the size of the power storage element that can be accommodated in the case increases, and the internal space of the case of the power storage element can be effectively utilized. Moreover, since the outer surface of the opening end portion is reduced in diameter to the inside of the case, the joining portion that joins the opening end portion and the lid plate hardly protrudes outward from the outer surface of the main body portion. Therefore, interference with other members can be suppressed.

  Moreover, in patent document 1, although the thickness of the opening edge part of a battery case main body is made thin, in order to make an opening edge part thin, a cutting process and a grinding process are required, and it says that a process becomes complicated. There's a problem. In this regard, in the present configuration, the inner surface of the opening end portion has a diameter smaller than the inner surface of the main body portion inward of the case. That is, both the outer surface and inner surface of the opening end are reduced in diameter in the same direction. Therefore, processing by a press is possible, and manufacture of a case becomes easy.

  In the electricity storage device of the present embodiment, the outer peripheral edge portion of the lid plate protrudes outward of the case from the outer surface of the opening end portion, and is positioned inward of the case from the outer surface of the main body portion. Is arranged. In this structure, the part (outer peripheral edge part) which protrudes outward from the opening edge part of a case among cover plates can be used for welding. Therefore, it is possible to secure a melting allowance necessary for maintaining the welding strength. Further, since the outer peripheral edge portion is located inside the outer surface of the main body portion, the outer peripheral edge portion does not protrude outward from the case. Therefore, it can suppress that the outer periphery part of a cover plate interferes with the other member located in the vicinity, maintaining the welding strength of a case and a cover plate.

  In the electricity storage device of the present embodiment, the lid plate and the opening end are welded from a direction intersecting the axial direction of the case. In this configuration, the lid plate and the open end can be easily welded.

  In the electricity storage device of this embodiment, the cross-sectional shape of the case is circular, elliptical, or oval. In this configuration, it is possible to easily reduce the diameter of the opening end as compared with the case where the cross-sectional shape is rectangular.

  In the electricity storage device of this embodiment, the electricity storage element is configured by winding an electrode plate, and the electrode plate is wound around the axis of the case. In this configuration, the power storage elements can be stored in the case with high density. Therefore, the internal space of the case can be used more effectively.

<Embodiment 1>
Hereinafter, the battery 10 which is Embodiment 1 of an electrical storage element is demonstrated with reference to FIG. 1 thru | or FIG. In the following description, the arrangement side of the cover plate 30 will be described as the lower side, and the arrangement side of the cover plate 40 will be described as the upper side. In each figure, the vertical direction is shown in the X direction as necessary. 1 to 10 schematically show the structure of the battery 10, and the shapes of the components are simplified as necessary.

1. Overall Structure of Battery 10 The battery 10 is a non-aqueous electrolyte secondary battery, more specifically, a lithium ion secondary battery. The battery 10 includes a power storage element 11, a case 20, a lower lid plate 30, an upper lid plate 40, a terminal plate 50, a negative electrode current collector 60, an external insulating plate 81, an internal insulating plate 85, And an insulating member 91.

  The power storage element 11 includes a positive electrode plate 12, a negative electrode plate 13, and a separator. The positive electrode plate 12 and the negative electrode plate 13 are obtained by applying each active material material on a metal foil. The positive electrode plate 12 and the negative electrode plate 13 correspond to the “electrode plate” of the present invention.

  An aluminum foil is used as the metal foil constituting the positive electrode plate 12. As a positive electrode active material, a well-known thing can be used as a positive electrode active material of a lithium ion battery, such as lithium complex oxide containing lithium and manganese.

  As the metal foil constituting the negative electrode plate 13, for example, copper foil or the like can be used. As the negative electrode active material, lithium metal, lithium-aluminum alloy or lithium-lead alloy that can absorb and release lithium is used. Known materials can be used as negative electrode active materials for lithium ion batteries, such as lithium alloys such as lithium-tin alloys, carbon materials such as graphite, coke, and organic fired bodies.

  As the separator, for example, a known separator as a lithium ion battery separator such as a polyethylene microporous membrane can be used.

  As shown in FIG. 3, the power storage element 11 is configured as a so-called winding type power storage element in which a positive electrode plate 12 and a negative electrode plate 13 are wound with a separator interposed therebetween. The positive electrode plate 12 and the negative electrode plate 13 are accommodated in the case 20 with the winding axis L <b> 1 aligned with the case center line Lo of the case 20. Therefore, in the relationship with the case 20, it is wound around the case center line Lo. And as shown in FIG. 3, uncoated part 12A, 13A in which each active material is not apply | coated is provided in the edge part of the X direction among each pole plate 12,13. The center line Lo corresponds to the “case axis” of the present invention.

  The case 20 is made of metal (for example, made of aluminum or aluminum alloy), for example. As shown in FIG. 1, the case 20 has a cylindrical shape penetrating vertically, and has an opening 20A at the upper end and an opening 20B at the lower end. The cross-sectional shape of the case 20 is an oval shape. As shown in FIG. 4, the storage element 11 is accommodated inside the case 20 while the winding axis L <b> 1 coincides with the case center line Lo. The power storage element 11 is housed inside the case 20 with the uncoated portion 13A of the negative electrode plate 13 facing upward and the uncoated portion 12A of the positive electrode plate 12 facing downward.

  The lower lid plate 30 is made of metal (for example, aluminum or aluminum alloy). As shown in FIGS. 1 and 4, the lower lid plate 30 is disposed at the lower opening end 25 of the case 20 and seals the lower opening 20 </ b> B.

  Further, a connecting portion 35 is formed on the lower lid plate 30. The connecting portion 35 protrudes inward of the case 20 and is disposed inside the uncoated portion 12A of the positive electrode plate 12 accommodated in the case 20. The connection part 35 is joined to the uncoated part of the positive electrode plate 12 by, for example, ultrasonic welding. In addition, the lower cover plate 30 functions as a positive electrode terminal in this example.

  The upper lid plate 40 is made of metal (for example, made of aluminum or aluminum alloy) and has a liquid injection port 49 for injecting a nonaqueous electrolytic solution. As shown in FIGS. 1 and 4, the upper lid plate 40 is disposed at the upper opening end 23 of the case 20 and seals the upper opening 20 </ b> A.

  As shown in FIGS. 1 and 4, the terminal board 50 includes a terminal board main body 51 made of a metal plate made of copper or a copper alloy, and a rivet 55 that penetrates the terminal board main body 51 downward. The terminal plate 50 is disposed on the upper surface of the upper lid plate 40 with the external insulating plate 81 interposed therebetween. The rivets 55 of the terminal plate 50 are terminals formed in the cylindrical portion 82 of the external insulating plate 81, the through hole 45 of the upper lid plate 40, the through hole 86 of the internal insulating plate 85, and the terminal connection portion 61 of the negative electrode current collector 60. The connection holes 62 are sequentially passed through and fixed by caulking.

  The external insulating plate 81 is made of an insulating material such as a synthetic resin and has a flat plate shape larger than the terminal plate 50. The external insulating plate 81 is disposed on the upper surface of the upper cover plate 40 and insulates the upper cover plate 40 from the terminal plate 50. The external insulating plate 81 has a cylindrical portion 82 and a flange 83. The cylindrical portion 82 extends downward from the external insulating plate 81 and is fitted inside the through hole 45 of the upper lid plate 40 and the through hole 86 of the internal insulating plate 85. The flange 83 is formed along the outer periphery of the external insulating plate 81 and surrounds the outer periphery of the terminal plate 50.

  The internal insulating plate 85 is made of an insulating material such as synthetic resin and has a flat plate shape larger than the terminal connection portion 61 of the negative electrode current collector 60. The internal insulating plate 85 is disposed on the lower surface of the upper lid plate 40, and between the upper lid plate 40 and the terminal connection portion 61 of the negative electrode current collector 60, and between the upper lid plate 40 and the rivets 55 of the terminal plate 50. Insulate between. The internal insulating plate 85 has a through hole 86 through which the rivet 55 of the terminal plate 50 passes, and a flange 87. The flange 87 is formed along the outer periphery of the internal insulating plate 85 and is configured to surround the outer periphery of the terminal connection portion 61 of the negative electrode current collector 60.

  The negative electrode current collector 60 is made of copper or a copper alloy, and includes a terminal connection portion 61 and a current collector connection portion 71 as shown in FIGS. 1, 5, and 6. The terminal connecting portion 61 is flat and has a terminal connecting hole 62. The terminal connecting portion 61 is disposed on the lower surface of the upper lid plate 40 with the internal insulating plate 85 interposed therebetween. A rivet 55 of the terminal plate 50 passes through the terminal connection hole 62 of the terminal connection portion 61, and the terminal connection portion 61 is fixed to the upper lid plate 40 by caulking the tip.

  As shown in FIGS. 5 and 6, the current collector connection portion 71 has a box shape, and includes a bottom wall 72, a pair of side walls 73 and 74 that are cut substantially vertically from both sides of the bottom wall 72, and a top wall. 75. The pair of side walls 73 and 74 are fitted inside the uncoated portion 13 </ b> A of the negative electrode plate 13. The pair of side walls 73 and 74 are joined to the uncoated portion 13A of the negative electrode plate 13 by, for example, ultrasonic welding. The upper surface wall 75 faces the terminal connection portion 61 in parallel. An escape hole 76 is provided in the upper surface wall 75 so as to avoid interference with the rivet 55 of the terminal plate 50. The negative electrode current collector 60 has a configuration in which a single metal plate is bent into an S-shaped cross section, and the terminal connection portion 61 and the current collector connection portion 71 are connected by a pair of connection walls 77. Yes. In FIG. 1, the shape of the negative electrode current collector 60 before the terminal connection portion 61 is bent is shown.

  The insulating member 91 is made of an insulating material such as a synthetic resin and has an annular shape as shown in FIG. As shown in FIG. 4, the insulating member 91 is fitted on the outside of the uncoated portion 13 </ b> A of the negative electrode plate 13 to insulate the uncoated portion 13 </ b> A from the case 20.

2. Procedure for assembling battery 10 First, the negative electrode current collector 60 is joined to the uncoated portion 13A on the negative electrode side of the power storage element 11, and the lower lid plate 30 is joined to the uncoated portion 12A on the positive electrode side. Next, the electricity storage element 11 in which the negative electrode current collector 60 and the lower lid plate 30 are joined is inserted into the case 20 from the lower opening 20B. Thereafter, the lower lid plate 30 is joined to the lower opening 20B of the case 20 by welding. Then, the insulating member 91 is inserted into the case 20 through the upper opening 20 </ b> A, and is fitted to the outer periphery of the negative electrode current collector 60.

  Next, the internal insulating plate 85, the upper lid plate 40, the external insulating plate 81, and the terminal plate 50 are assembled to the terminal connection portion 61 of the negative electrode current collector 60. Thereafter, the rivets 55 of the terminal plate 50 are caulked to fix the internal insulating plate 85, the upper lid plate 40, the external insulating plate 81, and the terminal plate 50 to the terminal connecting portion 61.

  Next, the connecting wall 77 of the negative electrode current collector 60 is bent into an S shape, and then the upper cover plate 40 is fitted into the upper opening 20 </ b> A of the case 20. Thereafter, the upper cover plate 40 is joined to the upper opening 20A of the case 20 by welding. After that, the non-aqueous electrolyte is injected from the injection hole 49 of the upper lid plate 40, and finally the injection hole 49 is sealed, whereby the battery 10 is obtained.

3. As shown in FIGS. 1 and 4, the case 20 includes a main body 21, an open end 23 positioned above the main body 21, and a bottom of the main body 21. And an open end 25 located on the side. As shown in FIGS. 4 and 7, the upper opening end 23 has an outer surface 23 a that is radially inward of the case 20 relative to the outer surface 21 a of the main body 21 (on the side toward the case center line Lo, on the right side of FIG. 7). ). In the example of FIG. 7, the outer surface 21 a of the main body 21 has a distance “D1” from the case center line Lo, the outer surface 23 a of the opening end 23 has a distance “D2” from the case center line Lo, and the upper opening The outer surface 23 a of the end portion 23 is reduced in diameter by ΔD over the entire circumference than the outer surface 21 a of the main body portion 21. In other words, the outer surface 23 a of the upper opening end 23 has a step that is recessed inward of the case 20 with respect to the outer surface 21 a of the main body 21.

  Further, as shown in FIG. 7, the inner surface 23 b of the upper open end 23 is reduced in diameter by ΔD over the entire circumference from the inner surface 21 b of the main body 21, as with the outer surface. In other words, the inner surface 23 b of the upper opening end 23 is provided with a step that protrudes inward of the case 20 with respect to the inner surface 21 b of the main body 21.

  As described above, the opening end portion 23 has both the outer surface 23 a and the inner surface 23 b reduced in diameter by the same size on the radially inner side of the case 20 with respect to the main body portion 21. The open end 23 is connected to the main body 21 via a taper 22, and the plate thickness of the open end 23 is the same as the plate thickness of the case 20 (the plate thickness of the main body 21). .

  Further, as shown in FIG. 8, the same applies to the lower opening end 25, and both the outer surface 25 a and the inner surface 25 b are arranged on the radially inner side of the case 20 with respect to the main body portion 21 (the side toward the case center line Lo). Thus, the diameter is reduced by ΔD over the entire circumference on the right side of FIG. The opening end portion 25 is connected to the main body portion 21 via a taper 24, and the plate thickness of the opening end portion 25 is the same as the plate thickness of the case 20 (the plate thickness of the main body portion 21). .

  As shown in FIG. 1, the upper lid plate 40 includes a lid body 41 and ribs 43. The lid body 41 has an oval shape that is slightly larger than the opening 20 </ b> A on the upper side of the case 20. As shown in FIGS. 4 and 7, the upper lid plate 40 is assembled to the upper opening end 23 of the case 20 and seals the upper opening 20 </ b> A of the case 20. Specifically, the outer peripheral edge 42 of the lid main body 41 is assembled so as to overlap the end surface 23c of the opening end 23, and the lower surface 41A of the lid main body 41 is the end surface 23c of the opening end 23. The relationship is consistent with the height.

  The rib 43 is formed on the lower surface 41 </ b> A of the lid body 41. The rib 43 has an oval shape that follows the shape of the inner surface of the opening end 23, and fits inside the opening end 23. By fitting the rib 43, the upper lid plate 40 can be positioned with respect to the opening end portion 23.

  The upper lid plate 40 is joined to the opening end portion 23 of the case 20 by laser welding the joint portion with the opening end portion 23 over the entire circumference. In the laser welding, as shown in FIGS. 4 and 7, a laser beam F is irradiated in a horizontal direction (a direction orthogonal to the case center line Lo) from a laser light source G installed on the side of the case 20. Done.

  As described above, the opening end 23 of the case 20 is reduced in diameter toward the inside in the radial direction of the case 20. Therefore, as shown in FIG. 7, even if the welded portion J by laser welding has a shape that swells with respect to the original outer shape, the welded portion J is positioned on the inner side of the outer surface 21a of the main body portion 21 (the right side in FIG. ). Further, even when a part of the weld J protrudes from the outer surface 21a of the main body 21 to the outside (left side in FIG. 7), the opening end 23 is not reduced in diameter and is flush with the main body 21. Compared with (for example, the case of FIG. 9), it is possible to suppress the amount of outward protrusion.

  Further, as shown in FIG. 7, the outer peripheral edge 42 of the lid body 41 protrudes from the outer surface 23 a of the opening end 23 to the outside of the case 20 (left side in FIG. 7). Specifically, the outer peripheral edge portion 42 protrudes outward from the outer surface 23 a of the opening end portion 23 over the entire circumference of the lid main body 41. If the outer peripheral edge portion 42 is protruding, the protruding portion can be welded to the outer surface 23a of the opening end 23. Therefore, it is possible to ensure the melting allowance necessary for maintaining the welding strength by melting only the side near the outer surface 23a of the open end 23. Further, the outer peripheral edge portion 42 of the lid main body 41 is located on the inner side (right side in FIG. 7) of the case 20 than the outer surface 21 a of the main body portion 21 of the case 20. Specifically, the outer peripheral edge 42 is located on the inner side of the case 20 from the outer surface 21 a of the main body 21 of the case 20 over the entire circumference of the lid main body 41. By doing in this way, it can suppress that the outer-periphery edge part 42 of the upper side cover plate 40 interferes with the other member located in the vicinity.

  Next, as shown in FIG. 1, the lower lid plate 30 includes a lid body 31 and a horizontal flange portion (corresponding to the “outer peripheral edge portion” of the present invention) 32. The lid body 31 has an oval shape corresponding to the shape of the open end 25 on the lower side of the case 20. The horizontal flange portion 32 is formed on the entire outer periphery of the lid body 31. The horizontal flange portion 32 has a level difference corresponding to the plate thickness between the lid body 31 and extends horizontally from the outer peripheral portion of the lid body 31 along the surface of the lid body 31.

  As shown in FIGS. 4 and 8, the lower lid plate 30 is assembled to the lower opening end 25 of the case 20 and seals the lower opening 20 </ b> B of the case 20. Specifically, the lid main body 31 is fitted inside the opening end 25, and the horizontal flange portion 32 is arranged so as to overlap the end surface 25 c of the opening end 25. The lower surface 31 </ b> A has a relationship that coincides with the height of the end surface 25 c of the opening end portion 25.

  The lower lid plate 30 is joined to the opening end 25 of the case 20 by laser welding the joint portion with the opening end 25 over the entire circumference. Similarly to the upper opening end 23, the lower opening end 25 is also reduced in diameter in the radial direction of the case 20. Therefore, as shown in FIG. 8, even if the welded portion J by laser welding has a shape that swells with respect to the original outer shape, the welded portion J is located inside the outer surface 21 a of the main body portion 21 (right side in FIG. 8). It is possible to fit in. Further, even when a part of the welded portion J jumps out from the outer surface 21a of the main body portion 21 to the outside (left side in FIG. 8), the amount of outward jumping is smaller than when the opening end portion 25 is not reduced in diameter. It is possible to suppress.

  Further, as shown in FIG. 8, the horizontal flange portion 32 protrudes from the outer surface 25a of the opening end portion 25 to the outside of the case 20 (left side in FIG. 8). Specifically, the horizontal flange portion 32 protrudes from the outer surface 25 a of the opening end portion 25 to the outside of the case 20 over the entire circumference of the lid main body 31. If the horizontal flange 32 protrudes, the protruding portion can be welded to the outer surface 25a of the opening end 25. Therefore, the melting allowance required to maintain the welding strength can be ensured only by melting only the side close to the outer surface 25a in the open end 25. Further, the horizontal flange portion 32 of the lower lid plate 30 is located on the inner side (right side in FIG. 8) of the case 20 than the outer surface 21 a of the main body portion 21 of the case 20. Specifically, the horizontal flange portion 32 is located on the inner side of the case 20 from the outer surface 21 a of the main body portion 21 of the case 20 over the entire circumference of the lid main body 31. By doing in this way, it can control that horizontal flange part 32 of lower lid 30 interferes with other members located near.

4). Detail of shape of case 20 (4-A) Distance from case center line Lo to inner surface 23b of open end 23 Case 20 of battery 10 of the present embodiment has a distance from case center line Lo to inner surface 23b of open end 23. The distance D3 is made to coincide with the distance D4 of the corresponding part of the battery 210 having the conventional structure.

  Specifically, FIG. 9 is a cross-sectional view of a battery 210 having a conventional structure. Similar to the battery 10, the battery 210 includes a case 220 that houses the power storage element 11. The main body 221 of the case 220 has a linear shape and does not have a step at the opening end 225. In the case 20 of the battery 10 of the present embodiment, the distance D3 (see FIG. 7) from the case center line Lo to the inner surface 23b of the open end 23 is from the case center line Lo of the battery 210 to the inner surface 221b of the main body 221. It is equal to the distance D4 (see FIG. 9). In FIG. 9, the cover plate is omitted.

  As described above, by setting the distance D3 from the case center line Lo to the inner surface 23b to be the same as the conventional distance D4 (D3 = D4), while providing a step of ΔD at the opening end 23, The area of the opening itself is not changed. Therefore, if it is the electrical storage element 11 of the same size as the battery 210 of the conventional structure, it can be accommodated in the case 20 from the opening end 23 or the opening end 25.

  Further, in the main body portion 21 of the case 20 that is below the step, the space is widened by the step with respect to the opening end portion 23. Therefore, for example, the amount of the electrolytic solution can be increased. In addition, it is necessary to secure a predetermined clearance between the case 20 and the power storage element 11, but since the step can be used for the clearance, the insertion property is slightly reduced, but compared to the case where there is no step, It is also possible to increase the size of the power storage element 11. Therefore, the performance of the battery can be improved. Note that the deterioration of the insertability can be eliminated by using a guide jig or the like that assists the insertion of the power storage element 11. In addition, by providing a step of ΔD, the joint portion J that joins the opening end portion 23 and the upper lid plate 40 hardly protrudes outward from the outer surface 21 a of the main body portion 21 of the case 20. Therefore, interference with other members can be suppressed.

  In the above description, the upper opening end 23 is described as an example, but the lower opening end 25 is the same, and the distance from the case center line Lo to the inner surface 25b of the opening end 25 is as follows. The relationship coincides with the distance of the corresponding portion of the battery 210 having the conventional structure.

(4-B) Plate Thickness and Step Size of Case 20 In this battery 10, the plate thickness T1 (see FIG. 7) of the case 20 is made thinner than the plate thickness To (see FIG. 9) of the case 210 having the conventional structure. ing. Then, the reduction in thickness (To-T1) and the step size ΔD are made to coincide with each other, and the distance T2 (see FIG. 10) from the inner surface 23b of the opening end 23 to the outer surface 21a of the main body 21 is conventional. The relation (T2 = To) coincides with the plate thickness To (see FIG. 9) of the case 220 of the battery 210 having the structure. That is, the total dimension of the plate thickness T1 of the case 20 and the step size ΔD is equal to the plate thickness To of the case 220 of the battery 210 having the conventional structure.

  By doing so, the outer dimension of the case 20 does not become larger than that of the conventional structure, and becomes the same dimension as the outer dimension of the case 220 of the battery 210 having the conventional structure.

  The reason why the thickness T1 of the case 20 can be made thinner than the thickness To of the case 210 having the conventional structure is as follows. In the battery 10, as described with reference to FIG. 7, the outer peripheral edge portion 42 of the lid main body 41 protrudes outward (left side in FIG. 7) from the outer surface 23 a of the opening end portion 23. If the outer peripheral edge portion 42 is protruding, the protruding portion can be welded to the outer surface 23a of the opening end 23. Therefore, as compared with the case where there is no protrusion (for example, in the case of FIG. 14), it is possible to ensure the melting allowance necessary for maintaining the welding strength by melting only the side near the outer surface 23 a of the opening end 23. . That is, since it is not necessary to melt the side close to the inner surface 23b, the plate thickness T1 of the case 20 can be reduced.

  In the above description, the upper opening end 23 is described as an example. However, the same applies to the lower opening end 25, and the distance from the inner surface 25 b of the opening end 25 to the outer surface 21 a of the main body 21. However, the relation is in agreement with the plate thickness To of the case 220 of the battery 210 having the conventional structure.

(4-C) Numerical Example of Case FIG. 11 shows a numerical example of the case 20, where the total thickness of the plate thickness T1 of the case 20 and the step size ΔD is the plate thickness To of the case 220 having the conventional structure. The relationship is equal to For example, in the case of No. 1 case 20, the thickness of the case 20 is 0.9 mm, and the step size ΔD is 0.2 mm. Since the sum of both dimensions is 1.1 mm, it is equal to the plate thickness To of the case 220 having the conventional structure. In the case of No. 2 case 20, the plate thickness of case 20 is 0.7 mm and the step size ΔD is 0.2 mm. Since the sum of both dimensions is 0.9 mm, it is equal to the plate thickness To of the case 220 having the conventional structure. The numerical example described above is an example. For example, in the case of No1, the step size ΔD is set to 0.3 mm or 0.25 mm, and the plate thickness T1 of the case 20 is set to 0.8 mm or 0.8 mm. It is good also as 75 mm.

  In addition, the battery 10 having this structure can be applied to a battery of several Ah to 100 Ah or less (preferably 5 Ah to about 50 Ah).

5). Explanation of the effect The upper lid plate 40 is arranged with the outer peripheral edge portion 42 overlapped with the end surface 23c of the opening end portion 23 of the case 20, and the lower surface 41A of the lid main body 41 coincides with the height of the end surface 23c of the opening end portion 23. It has become a relationship. Therefore, compared with the case where the entire upper lid plate 40 is fitted into the opening end 23, the storage space for the power storage element 11 is widened in the vertical direction, and the size of the power storage element 11 that can be stored in the case 20 is vertical. Increase in size. Therefore, the internal space of the case 20 can be used effectively. Therefore, the energy density of the battery 10 is increased.

  Similarly, since the lower cover plate 30 is also arranged so that the horizontal flange portion 32 overlaps the end surface 25c of the opening end portion 25 of the case 20, the entire lower cover plate 30 is fitted inside the opening end portion 23. As compared with the case, the internal volume of the case 20 is increased. Therefore, the internal space of the case 20 can be used more effectively. Therefore, the energy density of the battery 10 is further increased.

  Further, according to the battery 10, the outer surfaces 23 a and 25 a of the open end portions 23 and 25 are reduced inward in the radial direction of the case 20. Therefore, even if the welded portion J has a shape that swells with respect to the original outer shape, the welded portion J can be accommodated inside the outer surface 21a of the main body portion 21 of the case 20, and the welded portion J becomes another member. Interference with can be suppressed.

  Further, according to the battery 10, not only the outer surfaces 23 a and 25 a of the open end portions 23 and 25, but also the inner surfaces 23 b and 25 b are reduced in diameter in the radial direction of the case 20. That is, both the outer surfaces and inner surfaces of the open ends 23 and 25 are reduced in diameter in the same direction, and the size ΔD is also equal on the outer surface side and the inner surface side. Since the process of reducing the diameters of the open end portions 23 and 25 is performed in the state of a single component, the open end portions 23 and 25 can be pressed, and the case 20 can be easily manufactured.

  Further, when the diameter of the opening end 225 is reduced without changing the outer dimensions of the case 220 having the conventional structure, the opening area is reduced. Therefore, the size of the electricity storage element 11 accommodated in the case 220 is reduced accordingly, and the battery performance is reduced. On the other hand, if the size of the power storage element 11 is to be maintained, a step is required to increase the outer shape of the case 220 while keeping the size of the opening end 25.

  Therefore, the inventor studied the thickness T1 of the case 20, the structure of the fitting portion of the upper lid 40 with respect to the case 20, and the melting allowance between the case 20 and the upper lid 40.

  Then, attention is paid to the fact that when the outer peripheral edge portion 42 of the lid body 41 protrudes outward from the outer surface 23a of the opening end portion 23, the plate thickness on the case 20 side can be reduced due to the melting allowance during welding.

  Then, the plate thickness of the case 20 is made thinner than before, and the distance T2 from the inner surface 23b of the opening end 23 to the outer surface 21a of the main body 21 is made to coincide with the plate thickness To of the case 220 of the battery 210 having the conventional structure. Devised. Furthermore, a point has been devised in which the distance D3 from the case center line Lo to the inner surface 23b of the open end 23 matches the distance D4 of the corresponding part of the battery 210 having the conventional structure.

  With these devices, it has been achieved that the outer end dimensions of the case 20 and the size of the electricity storage element 11 are made equal to the conventional one while reducing the diameter of the open end portions 23 and 25 and suppressing the protrusion of the welded portion J to the outer shape of the case. . Further, in the main body portion 21 of the case 20 on the lower side of the step, the internal space is widened by the step. Therefore, the battery performance can be improved by increasing the amount of the electrolytic solution or increasing the size of the electricity storage element 11.

  That is, in the battery 10 of the present embodiment, the thickness of the case 20 can be effectively used as compared with the case 220 having a conventional structure that does not have a step.

  Further, according to the battery 10, the lid plates 30 and 40 are welded from the direction intersecting the case center line Lo of the case 20. Specifically, welding is performed from a direction orthogonal to the case center line Lo. If the welding direction (in this example, the direction of the laser beam F) intersects the case center line Lo, the laser beam is applied to the mating surfaces of the lid plates 40, 30 and the open end portions 23, 25. Easy to weld.

  Moreover, according to the battery 10, the cross-sectional shape of the case 20 is oval. If the cross-sectional shape is an ellipse, it is possible to easily reduce the diameter of the open end portions 23 and 25, and the workability is better than when the cross-sectional shape is a rectangle.

  Further, according to the battery 10, the positive electrode plate 12 and the negative electrode plate 13 are wound around the case center line Lo. With such a configuration, the power storage elements 11 can be stored in the case 20 at a high density, and the energy density of the battery 10 is further increased.

<Embodiment 2>
Next, Embodiment 2 of the present invention will be described with reference to FIG.
The second embodiment exemplifies a power storage device M. The power storage device M is a device in which a plurality of batteries 10 are connected in series, and includes a plurality of batteries 10A to 10D, an insulating sheet 100, and a bus bar 110.

  The batteries 10A to 10D are the batteries having the same basic configuration as the battery 10 of the first embodiment. The difference is that a metal plate functioning as a positive terminal plate 150 is provided on the upper lid plate 40. The positive terminal plate 150 is disposed at a position opposite to the negative electrode terminal 50 in the longitudinal direction of the upper lid plate 40 and is joined directly to the upper lid plate 40 by welding or the like. Since the case of the battery 10 is connected to the positive electrode, the case functions as a conduction path.

  As shown in FIG. 12, each of the batteries 10 </ b> A to 10 </ b> D is arranged with the short axis direction of the case 20 facing the Y direction in FIG. 10 while reversing the direction so that the positive and negative terminal plates 50 and 150 are adjacent to each other. Yes.

  The insulating sheet 100 is an insulating sheet material. As shown in FIG. 12, the insulating sheet 100 is disposed between the adjacent batteries 10A to 10D and insulates the batteries 10A to 10D. The bus bar 110 is, for example, a rectangular conductive metal plate, and electrically connects the positive and negative terminal plates 50 and 150 of the two adjacent batteries 10A to 10D.

  As already described in the first embodiment, each of the batteries 10A to 10D has the opening end portions 23 and 25 reduced in diameter to the inside of the case 20, so that the welded portion J expands with respect to the original outer shape. Even if it is, the welding part J can be stored inside the outer surface 21a of the case 20. Therefore, it can suppress that the welding part J interferes with the insulating sheet 100, and damages this.

<Other embodiments>
The present invention is not limited to the embodiments described with reference to the above description and drawings. For example, the following embodiments are also included in the technical scope of the present invention.
(1) In the first and second embodiments, the lithium ion secondary battery is illustrated as an example of the power storage element, but the present invention is applicable to any power storage element having the power storage element 11, the case 20, and the cover plates 30 and 40. It can be applied to batteries other than lithium ion secondary batteries and capacitors such as electric double layer capacitors.

  (2) In the first and second embodiments, as the shape of the case 20, the cylindrical case 20 having the openings 20A and 20B on both the upper and lower ends is illustrated. The case 20 only needs to have the openings 20A and 20B at least at one end, and may be a bottomed case 20 having an opening only at one end, for example.

  (3) In the first and second embodiments, an example in which the negative-side uncoated portion 13A is formed to protrude upward with respect to the main body portion of the power storage element 11, and the positive-side uncoated portion 12A is formed to protrude downward is shown. It was. The uncoated portions 12A and 13A are not limited to the case where they protrude in both the upper and lower directions as in the first and second embodiments. The application portions 312A and 313A may be configured to protrude upward and in a tab shape. In this case, since the uncoated portions 312A and 313A are only on one side, the case 20 can be downsized accordingly. Or if the magnitude | size of case 20 is the same, it is possible to enlarge the electrical storage element 11, and combined with the effect of this invention, the increase of an energy density can be aimed at further. In addition to the winding type as shown in FIG. 13, the power storage element 310 may be a stack type in which a plurality of electrode plates are stacked and positive and negative uncoated portions protrude upward in a tab shape.

  (4) In the first and second embodiments, the power storage element 11 is arranged with respect to the case 20 so that the winding axis L1 coincides with the case center line Lo. In addition to this, the winding axis L1 may be arranged to be orthogonal to the case center line Lo. In addition, if the electrical storage element 11 is accommodated with the winding axis L1 orthogonal to the case 20 having an oval cross section, it is possible to accommodate a thin uncoated portion in the R portion of the corner. Therefore, even if the internal volume is smaller than that of the square case, the same size of the electricity storage elements 11 can be accommodated, and the energy density can be increased. Moreover, in this example, the electrical storage element 11 is good also as a stack type which laminates | stacks several electrode plates and an uncoated part protrudes at both ends. In this case, it can be said that the phantom line connecting the uncoated portion 12A on the positive electrode side and the uncoated portion 13A on the negative electrode side is orthogonal to the case center line Lo.

  (5) In the first and second embodiments, the oval shape is exemplified as the cross-sectional shape of the case 20, but it may be, for example, a circular shape or an elliptical shape. The cross-sectional shape may be a square. The square-shaped case 20 can be manufactured, for example, by the following manufacturing method. A rectangular metal flat plate is prepared, and a step is provided by pressing near a pair of opposing sides. This step is a step that reduces the diameter of the opening end of the case 20. Next, the other pair of opposite sides different from the above pair are bent into a square tube shape and the overlapped portions are welded. In this way, the rectangular case 20 having the reduced diameters of the open end portions 23 and 25 is manufactured. If the case 20 is square, the battery and shape can be matched to the conventional battery shape, and replacement with the battery of the present invention with increased energy density is facilitated.

  (6) In the first and second embodiments, as shown in FIG. 7, an example in which the outer peripheral edge 42 of the upper cover plate 40 protrudes outward (left side in FIG. 7) from the outer surface 23 a of the opening end 23. Indicated. The outer peripheral edge portion 42 of the upper lid plate 40 only needs to be placed on the end surface 23c of the opening end portion 23, and the tip of the outer peripheral edge portion 42 is located inside the outer surface 23a of the opening end portion 23 as shown in FIG. (Right side in FIG. 14).

  (7) In the first and second embodiments, the example in which the upper opening end 23 has both the outer surface 23a and the inner surface 23b reduced in diameter to the inside of the case 20 has been described, but at least the outer surface 23a is reduced in diameter. The inner surface 23b side may not be reduced in diameter. The same applies to the lower opening end 25, as long as at least the outer surface 25a has a reduced diameter, and the inner surface 25b does not have to be reduced in diameter.

  (8) In the first and second embodiments, an example in which the upper lid plate 40 and the lower lid plate 30 are laser-welded to the case 20 has been shown, but the welding method is TIG welding or electron beam welding in addition to laser. Also good. In the first and second embodiments, the lid plates 30 and 40 are welded from the direction orthogonal to the case center line Lo. However, the welding direction is not limited to the orthogonal direction, and the axis of the case 20 Any direction that intersects the direction (the direction of the case center line Lo) may be used.

  (9) In the first and second embodiments, the case 20, the upper lid plate 40, and the lower lid plate 30 are made of aluminum or aluminum alloy. However, for example, stainless steel materials and plated steel plates (for example, , Nickel plating) and the like.

  (10) In the first and second embodiments, the tip of the outer peripheral edge portion 42 of the lid main body 41 of the upper lid plate 40 is located inward of the case 20 rather than the outer surface 21a of the main body portion 21 of the case 20 (right side in FIG. 7). An example is shown. A part of the outer peripheral edge portion 42 of the lid main body 41 of the upper lid plate 40 may be configured to protrude from the outer surface 21a of the main body portion 21 of the case 20 to the outside of the case 20 (left side in FIG. 7). Good. That is, as shown in FIG. 12, the semicircular portions on both sides in the longitudinal direction of the upper lid plate 40 are not adjacent to other batteries when a plurality of batteries are connected in series to form an assembled battery. Therefore, the semicircular portions on both sides in the longitudinal direction may be configured such that the outer peripheral edge portion 42 of the lid main body 41 protrudes outward of the case 20 from the outer surface 21 a of the main body portion 21 of the case 20. Similarly, the semicircular portions on both sides in the longitudinal direction of the lower lid plate 30 may be configured such that the horizontal flange portion 32 protrudes outward from the outer surface 21 a of the main body portion 21 of the case 20. Good.

DESCRIPTION OF SYMBOLS 10 ... Battery 11 ... Power storage element 12 ... Positive electrode plate (equivalent to "electrode board" of this invention)
13 ... Negative electrode plate (corresponding to "electrode plate" of the present invention)
DESCRIPTION OF SYMBOLS 20 ... Case 21 ... Main-body part 23 ... Lower opening edge part 23a ... Outer surface 23b ... Inner surface 23c ... End surface 25 ... Upper opening edge part 25a ... Outer surface 25b ... inner surface 25c ... end surface 30 ... lower cover plate 33 ... horizontal flange (corresponding to "outer peripheral edge" of the present invention)
40 ... Upper cover plate 42 ... Outer peripheral edge 50 ... Terminal plate 60 ... Negative electrode current collector

Claims (5)

A case having a cylindrical shape and having an opening at at least one end;
A lid plate that closes the opening of the case;
A power storage element housed in the case,
The case has a main body portion and an opening end portion that is an end portion on the opening portion side,
The lid plate is arranged with an outer peripheral edge portion overlapped with an end face of the opening end portion,
The outer surface of the opening end is reduced in diameter to the inside of the case than the outer surface of the main body part,
The inner surface of the opening end is reduced in diameter to the inside of the case than the inner surface of the main body ,
The outer peripheral edge of the lid plate protrudes outward of the case from the outer surface of the opening end,
The electrical storage element in which the said cover plate and the said opening edge part are welded from the direction which cross | intersects the axial direction of the said case . The electricity storage device according to claim 1,
Wherein the outer peripheral edge of the cover plate, the front SL main body storage element which is arranged at a position inward of the case than the outer surface of the. The electric storage device according to claim 1 or 2 ,
The cross-sectional shape of the case is a power storage element having a circular shape, an elliptical shape, or an oval shape. It is an electrical storage element as described in any one of Claim 1 thru | or 3 , Comprising:
The electricity storage element is configured by winding an electrode plate, and the electrode plate is wound around an axis of the case. The electrical storage apparatus formed by connecting two or more electrical storage elements as described in any one of Claims 1 thru | or 4 .

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