JP2019175687A - Power storage device - Google Patents

Abstract

To provide a power storage device capable of restraining loss of output efficiency of the power storage device, while restraining thermal effect on an insulation member when welding a case.SOLUTION: An electrode terminal 16 has a terminal joining member 31, and a rivet member 32c electrically connected therewith. The rivet member 32c has a shank 34 penetrating a rectangular plate lid 14 and a terminal juncture 31, and a caulking part 35 caulked on the outside of a case 11. The shank 34 is placed in the center of the lid 14 in the short direction. Assuming that the dimension of the lid 14 in the short direction is W, the distance from the one long edge part 14d of the lid 14 in the short direction thereof to the outer peripheral surface 34a of the shank 34 is P1, and the distance from the other long edge part 14d of the lid 14 to the outer peripheral surface 34a of the shank 34 is P2, cross sectional area of the shank 34 is larger than ((W-(P1+P2))/2)π. The distances P1 and P2 are set to 4 mm, respectively.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a power storage device including a rivet member.

  Conventionally, vehicles such as EVs (Electric Vehicles) and PHVs (Plug in Hybrid Vehicles) have been mounted with lithium-ion secondary batteries, nickel-hydrogen secondary batteries, and the like as power storage devices that store electric power supplied to electric motors and the like. . The secondary battery includes an electrode assembly in which a positive electrode and a negative electrode are insulated from each other, and a case that houses the electrode assembly. The electrode assembly includes a positive electrode tab group in which positive electrode tabs protruding from one side of the positive electrode are stacked, and a negative electrode tab group in which negative electrode tabs protruding from one side of the negative electrode are stacked. The case includes a case main body that houses the electrode assembly, and a plate-like lid that is welded to the case main body in a state where the opening of the case main body is closed. In addition, the secondary battery includes an electrode terminal of each polarity that exchanges electricity with the electrode assembly, and a conductive member of each polarity that electrically connects the tab group having the same polarity and the electrode terminal.

  In the secondary battery described in Patent Document 1, the electrode terminal includes a plate-like terminal bonding member disposed along the outer surface of the lid, and a rivet member that electrically connects the conductive member and the terminal bonding member. . The rivet member has a columnar shaft portion that penetrates the lid and the terminal joining member, and a crimped portion that is caulked outside the case. The secondary battery includes a plate-like insulating member that is disposed between the outer surface of the lid and the terminal bonding member and insulates the lid from the terminal bonding member.

JP2015-220122A

  By the way, in a power storage device, suppression of a decrease in output efficiency is desired. As one method for suppressing a decrease in output efficiency, a method of increasing the cross-sectional area of the shaft portion by increasing the diameter of the shaft portion of the rivet member and reducing the electrical resistance of the rivet member can be considered. However, when the diameter of the shaft portion is increased, the terminal joining member through which the shaft portion penetrates also increases, and when the terminal joining member increases, the insulating member also increases. As a result, the distance between the edge of the insulating member and the edge of the lid is reduced. Then, there exists a possibility that an insulating member may melt or deform | transform by the heat at the time of welding a case main body and a lid | cover.

  The present invention has been made to solve the above-described problem, and an object of the present invention is to provide a power storage device that can suppress a decrease in output efficiency of a power storage device while suppressing the thermal effect upon welding of the case from affecting the insulating member. To provide an apparatus.

A power storage device for solving the above problems includes an electrode assembly having a tab group in which electrodes are stacked and tabs having a shape protruding from the electrode are stacked, a case main body that houses the electrode assembly, and A case having a rectangular plate-like lid welded to the case main body in a state where the opening of the case main body is closed, a plate-like terminal joining member disposed along the outer surface of the lid, and the terminal joining member An electrode terminal having a rivet member electrically connected to the electrode group; a conductive member electrically connecting the tab group and the electrode terminal; and the terminal bonding member disposed between the terminal bonding member and the lid. A plate-like insulating member that insulates the member and the lid, and the rivet member includes a shaft portion that penetrates the lid and the terminal joining member, and a caulking portion that is caulked outside the case. Power storage device Then, the dimension in the short direction of the lid is W, the distance from one long edge portion of the lid to the outer peripheral surface of the shaft portion in the short direction of the lid is P1, and the other length of the lid is when the distance from the edge to the outer peripheral surface of the shaft portion and the P2, the cross-sectional area of the shank, ((W- (P1 + P2 )) / 2) greater than ² [pi, the distance P1 and the distance P2 Is summarized as being 4 mm or more.

According to this, the heat influence at the time of welding a case main body and a lid | cover is made by making distance P1, P2 from the long edge part of a lid | cover in the transversal direction of a lid | cover to the outer peripheral surface of a shaft part each 4 mm or more. And it can suppress reaching the edge part in alignment with the long edge part of a lid | cover among the edge parts of an insulating member. That is, at the time of welding the case, it is possible to suppress melting or deformation of the edge portion along the long edge portion of the lid among the edge portions of the insulating member. Further, the cross-sectional area of the shaft portion, when the cross-sectional shape of the shank is true circular shape, i.e. the cross-sectional area ((W- (P1 + P2) ) / 2) is made larger than when it is ² [pi, conductive The electrical resistance between the member and the terminal joining member can be reduced. Therefore, a decrease in output efficiency can be suppressed.

In the power storage device, when the distance from the short edge portion of the lid in the longitudinal direction of the lid to the outer peripheral surface of the shaft portion is Q, the distance Q is preferably 4 mm or more.
According to this, by setting the distance Q to 4 mm or more, it is possible to prevent the thermal effect when welding the case body and the lid from reaching the edge along the short edge of the lid among the edges of the insulating member. it can. That is, it can suppress that the edge part along the short edge part of a lid | cover melt | dissolves or deform | transforms among the edge parts of an insulating member at the time of welding of a case.

In the power storage device, it is preferable that a plurality of the rivet members are arranged in the longitudinal direction of the lid.
According to this, it is possible to easily reduce the electrical resistance between the conductive member and the terminal joining member only by increasing the number of rivet members.

  In the power storage device, the conductive member has a rectangular plate shape extending in the longitudinal direction of the lid, and includes an electrode connection portion to which the tab group is welded and a terminal connection portion to which the rivet member is bonded. Preferably, the electrode connection part and the terminal connection part are present at different positions in the longitudinal direction of the conductive member.

  When the electrode connection portion and the terminal connection portion are present at the same position in the longitudinal direction of the conductive member, the tab group is joined by welding to the same portion as the portion where the rivet member is joined by welding in the longitudinal direction of the conductive member. For example, if a bead is formed at the time of welding the rivet member and the conductive member is uneven, there is a possibility that the tab group cannot be welded to the conductive member satisfactorily. On the other hand, since the electrode connection portion and the terminal connection portion are present at different positions in the longitudinal direction of the conductive member, the tab group is tabbed in a portion different from the portion where the rivet member is joined in the longitudinal direction of the conductive member. Joined by welding groups. Therefore, the tab group can be favorably welded to the conductive member.

  In the power storage device, the conductive member is disposed along the inner surface of the lid, and has a first plate portion having a terminal connection portion to which the rivet member is joined, and the first plate portion, And a second plate portion having an electrode connection portion to which the tab group is welded, and a third plate portion connecting the first plate portion and the second plate portion, and viewed from the thickness direction of the lid. In this case, it is preferable that a part of the electrode connection part overlaps at least a part of the terminal connection part.

  According to this, the rivet member is joined to the first plate portion, and the tab group is joined to the second plate portion at a different height from the first plate portion. Therefore, compared with the case where a tab group is welded and joined to the part to which the rivet member was joined in a conductive member, a tab group can be favorably welded with respect to a conductive member. Further, when viewed from the thickness direction of the lid, the electrode connection portion is also arranged at a position overlapping with the terminal connection portion, so that the electrode connection portion overlaps with a portion other than the terminal connection portion in the first plate portion. In addition, it extends to a position overlapping the terminal connection portion. Therefore, the dimension of the electrode connection portion can be increased as compared with the case where the electrode connection portion extends only in a position overlapping with the portion other than the terminal connection portion in the first plate portion. Therefore, the tab in the tab group welded to the electrode connection portion can also be increased in size in the longitudinal direction of the lid, and the cross-sectional area of the tab is increased. As a result, the electrical resistance of the tab can be reduced, and a decrease in output efficiency can be suppressed.

  In the power storage device, the electrode terminal includes an external connection terminal, the terminal joining member is disposed along the outer surface of the lid, and the plate-like first connection through which the shaft portion of the rivet member passes is provided. Part, a plate-like second connection part facing the first connection part, and a third connection part connecting the first connection part and the second connection part, and the external connection terminal It is preferable that the second connection portion extends from the second connection portion in a direction opposite to the direction from the second connection portion toward the first connection portion.

  According to this, since the freedom of arrangement of the rivet member with respect to the terminal joining member can be increased without changing the position of the external connection terminal in the longitudinal direction of the lid, a plurality of rivet members are attached to the terminal connection portion. It can be arranged or the shape of the rivet member can be changed. In this case, since the distance between the external connection terminal on the positive electrode side and the external connection terminal on the negative electrode side does not change, the same bus bar as the conventional one can be used.

Moreover, when the said electrical storage apparatus is seen from the thickness direction of the said lid | cover, it is preferable that the said crimping part is non-circular shape.
According to this, compared with the case where the crimping part is circular, the area exposed to the outside of the case is increased, so that the heat dissipation of the rivet member can be enhanced.

  ADVANTAGE OF THE INVENTION According to this invention, the fall of the output efficiency of an electrical storage apparatus can be suppressed, suppressing that the thermal influence at the time of welding of a case reaches an insulating member.

The perspective view of the secondary battery of 1st Embodiment. The fragmentary sectional view of the secondary battery of a 1st embodiment. The fragmentary sectional view of the secondary battery of a 1st embodiment. The fragmentary sectional view of the secondary battery of 2nd Embodiment. The partial top view of the secondary battery of 2nd Embodiment. The fragmentary sectional view of the secondary battery of 2nd Embodiment. The fragmentary sectional view of the secondary battery of a 3rd embodiment. The fragmentary sectional view of the secondary battery of a 3rd embodiment. The fragmentary sectional view of the secondary battery of 4th Embodiment. The fragmentary sectional view of the secondary battery of 4th Embodiment. The partial top view which shows another example of a rivet member.

(First embodiment)
Hereinafter, a first embodiment in which the power storage device is embodied as a secondary battery will be described with reference to FIGS.

  As shown in FIG. 1, a secondary battery 10 as a power storage device includes a case 11, an electrode assembly 12, and an electrolyte solution (not shown). The electrode assembly 12 and the electrolytic solution are accommodated in the case 11. The case 11 includes a bottomed cylindrical case body 13 and a rectangular flat plate-shaped lid 14 that closes the opening 13 a of the case body 13. The case main body 13 and the lid 14 constituting the case 11 are both made of metal (in this embodiment, made of aluminum). Further, the secondary battery 10 of the present embodiment is a prismatic battery whose appearance is square. Further, the secondary battery 10 of the present embodiment is a lithium ion battery.

  As shown in FIGS. 1 and 2, the case body 13 includes a rectangular plate-like bottom wall 13b, a long side wall 13c erected from a pair of long side edges of the bottom wall 13b, and a pair of bottom walls 13b. And a short side wall 13d erected from the short side edge. The lid 14 has an inner surface 14 a on the surface facing the inner side of the case 11 and an outer surface 14 b on the surface facing the outer side of the case 11. In this embodiment, the longitudinal dimension of the lid 14 is 150 mm, and the lateral dimension W of the lid 14 is 27 mm.

  The case 11 is formed by laser welding the case main body 13 and the lid 14 with the opening 13a of the case main body 13 containing the electrode assembly 12 closed by the lid 14. Specifically, the case main body 13 and the lid 14 are configured such that the laser is emitted from the case main body 13 side toward the lid 14 in a state where the lid 14 is overlapped on the distal end surfaces of the long side wall 13c and the short side wall 13d of the case main body 13. Welded by irradiation. The thickness of the long side wall 13c and the short side wall 13d of the case body 13 is 1 mm, respectively, and the thickness of the portion of the lid 14 that overlaps the front end surfaces of the long side wall 13c and the short side wall 13d of the case body 13 is 1 mm.

  The electrode assembly 12 includes a positive electrode 21 as a plurality of rectangular sheet-like electrodes, a negative electrode 22 as an electrode, and a separator 23. The electrode assembly 12 has a layered structure in which separators 23 are interposed between the positive electrode 21 and the negative electrode 22 and are laminated in a mutually insulated state. In the present embodiment, the longitudinal directions of the positive electrode 21 and the negative electrode 22 coincide with the longitudinal direction of the lid 14. The direction in which the positive electrode 21 and the negative electrode 22 are stacked is defined as a stacking direction. The stacking direction coincides with the short direction of the lid 14.

  The positive electrode 21 has a rectangular sheet-like positive electrode metal foil (for example, aluminum foil) 24 and a positive electrode active material layer 25 present on both surfaces of the positive electrode metal foil 24. The positive electrode 21 has a tab 26 protruding from a part of the long edge portion 21 a that is one side of the positive electrode 21. The positive electrode tab 26 is formed of the positive electrode metal foil 24 itself without the positive electrode active material layer 25. The negative electrode 22 includes a rectangular sheet-like negative electrode metal foil (for example, copper foil) 27 and a negative electrode active material layer 28 present on both surfaces of the negative electrode metal foil 27. The negative electrode 22 has a negative electrode tab 26 as a tab protruding from a part of the long edge portion 22 a which is one side of the negative electrode 22. The negative electrode tab 26 is composed of the negative electrode metal foil 27 itself without the negative electrode active material layer 28.

  Each positive electrode 21 is laminated so that the tabs 26 of the respective positive electrodes are arranged in a row along the lamination direction. Similarly, each negative electrode 22 is laminated so that the tabs 26 of the respective negative electrodes are arranged in a line along the lamination direction. The electrode assembly 12 includes a positive electrode tab group 15 in which positive electrode tabs 26 are stacked, and a negative electrode tab group 15 in which negative electrode tabs 26 are stacked. The tab group 15 of the present embodiment is gathered on one end side in the stacking direction and bent toward the other end side in the stacking direction. In the electrode assembly 12, an end face where the tab group 15 of each polarity exists is defined as a tab side end face 12a. The electrode assembly 12 is insulated from the case body 13 by covering the end surface except the tab side end surface 12a with the insulating sheet F.

  As shown in FIGS. 1 and 3, the secondary battery 10 electrically connects an electrode terminal 16 of each polarity that exchanges electricity with the electrode assembly 12, a tab group 15 of the same polarity, and the electrode terminal 16. And a conductive member 17 of each polarity. The conductive member 17 of the present embodiment has a rectangular plate shape. Each conductive member 17 has an electrode connection portion 17a to which the tab group 15 is welded on one end side in the longitudinal direction. In the present embodiment, the entire tab group 15 along the longitudinal direction of the conductive member 17 is welded to the lower surface of the conductive member 17. Each conductive member 17 is disposed between the inner surface 14 a of the lid 14 and the tab-side end surface 12 a of the electrode assembly 12.

  The electrode terminal 16 includes a rectangular plate-shaped terminal joining member 31 disposed along the outer surface 14 b of the lid 14, and a first rivet member 32 a and a second rivet that electrically connect the conductive member 17 and the terminal joining member 31. And a member 32b. The longitudinal direction of the terminal joining member 31 coincides with the longitudinal direction of the lid 14, and the short direction of the terminal joining member 31 coincides with the short direction of the lid 14. The first rivet member 32 a and the second rivet member 32 b are the same rivet member, and are arranged side by side in the longitudinal direction of the lid 14. The first rivet member 32a is disposed closer to the short edge portion 14e of the lid 14, and the second rivet member 32b is disposed on the opposite side of the first rivet member 32a from the short edge portion 14e of the lid 14. Each of the first rivet member 32 a and the second rivet member 32 b has a flat plate-like base portion 33 and a columnar shaft portion 34 protruding from the base portion 33. The base 33 is joined to the other end of the conductive member 17 in the longitudinal direction inside the case 11. The base 33 is joined to the lower surface of the conductive member 17. Therefore, the conductive member 17 has a terminal connection portion 17b to which the electrode terminal 16 is joined on the other end side in the longitudinal direction. The electrode connection portion 17 a and the terminal connection portion 17 b exist at different positions in the longitudinal direction of the conductive member 17 when viewed from the thickness direction of the lid 14. In other words, the electrode connection portion 17 a and the terminal connection portion 17 b are arranged in the longitudinal direction of the conductive member 17 without overlapping when viewed from the thickness direction of the lid 14.

  The shaft portion 34 passes through the through hole 14 c formed in the lid 14 and the through hole 31 a formed in one end portion of the terminal joining member 31 in the longitudinal direction, and protrudes to the outside of the case 11. The cross-sectional shape of the shaft portion 34 viewed from the axial direction is circular. The diameter of the shaft portion 34 is the same in the entire axial direction of the shaft portion 34. As shown in FIG. 2, the shaft portion 34 is located at the center of the lid 14 in the short direction. The shortest distance from one long edge portion 14d of the lid 14 in the short direction of the lid 14 to the outer peripheral surface 34a of the shaft portion 34 is P1, and the axis from the other long edge portion 14d of the lid 14 in the short direction of the lid 14 is an axis. The shortest distance to the outer peripheral surface 34a of the part 34 is set to P2. In the present embodiment, the distance P1 and the distance P2 are each set to 4 mm. Further, Q is the shortest distance from the short edge portion 14e of the lid 14 in the longitudinal direction of the lid 14 to the outer peripheral surface 34a of the shaft portion 34 of the first rivet member 32a. In the present embodiment, the distance Q is set to 4 mm.

  Each of the first rivet member 32 a and the second rivet member 32 b has a caulking portion 35 that is caulked outside the case 11 at the end of the shaft portion 34 opposite to the base portion 33. The caulking portion 35 has a circular shape as in the case of the shaft portion 34 when viewed from the thickness direction of the lid 14. The diameter of the caulking portion 35 is larger than the diameter of the shaft portion 34.

  The electrode terminal 16 includes an external connection terminal 36 that extends in the direction away from the lid 14 from the other end portion of the terminal joining member 31 in the longitudinal direction. The external connection terminal 36 is electrically connected to the terminal bonding member 31. A bus bar fastening nut (not shown) can be screwed onto the external connection terminal 36.

  The secondary battery 10 includes an outer insulating member 37 as an insulating member arranged outside the case 11 and an inner insulating member 38 arranged inside the case 11. The outer insulating member 37 and the inner insulating member 38 are made of resin. The outer insulating member 37 has a plate shape and is disposed between the terminal joining member 31 and the external connection terminal 36 and the outer surface 14 b of the lid 14. Therefore, the outer insulating member 37 insulates the terminal joining member 31 and the external connection terminal 36 from the outer surface 14 b of the lid 14. The longitudinal direction and the short direction of the outer insulating member 37 coincide with the longitudinal direction and the short direction of the lid 14, respectively. When viewed from the thickness direction of the lid 14, the outer shape of the outer insulating member 37 is slightly larger than the outer shape of the terminal bonding member 31.

  The inner insulating member 38 includes a rectangular plate-like insulating plate portion 41 disposed between the inner surface 14 a of the lid 14 and the other end portion of the conductive member 17 in the longitudinal direction. The first rivet member 32 a and the second rivet member 32 b penetrate the insulating plate portion 41. The inner insulating member 38 includes a wall portion 42 erected from the three edges of the insulating plate portion 41 toward the electrode assembly 12. The three wall portions 42 are U-shaped and open toward the center in the longitudinal direction of the lid 14 when viewed from the thickness direction of the lid 14. The inner insulating member 38 includes a housing portion 43 surrounded by a surface of the insulating plate portion 41 opposite to the surface facing the inner surface 14 a of the lid 14 and the inner surfaces of the three wall portions 42. One end portion of the conductive member 17 in the longitudinal direction is accommodated in the accommodating portion 43 and is sandwiched between the two wall portions 42 paired in the stacking direction. Further, the conductive member 17 is positioned so as not to move to the end side in the longitudinal direction of the lid 14 by the wall portion 42 extending along the stacking direction.

Next, a method for manufacturing a secondary battery will be described.
As shown in FIG. 3, the electrode terminal 16, the outer insulating member 37, and the inner insulating member 38 are assembled to the lid 14. The terminal connection portion 17b of the conductive member 17 is joined to the base portion 33 of the first rivet member 32a and the second rivet member 32b, and the inner insulating member 38 holds the conductive member 17.

  Next, the positive electrode tab group 15 of the electrode assembly 12 is welded to the electrode connection portion 17 a of the positive electrode conductive member 17, and the negative electrode of the electrode assembly 12 is bonded to the electrode connection portion 17 a of the negative electrode conductive member 17. The tab group 15 is welded. Next, the electrode assembly 12 is inserted into the case body 13 through the opening 13 a of the case body 13. Then, the secondary battery 10 is manufactured by joining the opening edge of the case body 13 and the lid 14.

Next, the operation of the first embodiment will be described using a comparative example.
The secondary battery of the comparative example is different from the secondary battery of the first embodiment only in the number of rivet members. The secondary battery 10 of the first embodiment includes two rivet members (the first rivet member 32a and the second rivet member 32b), whereas the secondary battery of the comparative example includes one rivet member. Prepare.

  In the first embodiment, when the secondary battery 10 is charged and discharged, the electrode assembly 12 and the external connection terminal 36 include the tab group 15, the conductive member 17, the first rivet member 32a, the second rivet member 32b, and the terminal. Electricity is exchanged through the joining member 31. For example, since a high current of about 140 A flows through the shaft portion 34 of the first rivet member 32a and the second rivet member 32b, the first rivet member 32a and the second rivet member 32b become high temperature. It is also known that the electrical resistance of a conductor is inversely proportional to the cross-sectional area of the conductor. That is, the electrical resistance decreases as the cross-sectional area increases.

The cross-sectional shape of the shaft portion 34 is a circular shape, and is arranged at the center of the lid 14 in the short direction. Further, the dimension in the short direction of the lid 14 is W, the distance from one long edge portion 14d of the lid 14 to the outer peripheral surface 34a of the shaft portion 34 is P1, and the other long edge portion 14d of the lid 14 is Since the distance to the outer peripheral surface 34a is P2, the diameter R of the shaft portion 34 of the rivet member is expressed as W− (P1 + P2). Therefore, in the comparative example, the cross-sectional area A of the shaft portion 34 becomes ((W- (P1 + P2) ) / 2) 2 π.

  In the first embodiment, the electrode terminal 16 includes two rivet members (a first rivet member 32a and a second rivet member 32b). For this reason, the cross-sectional area S1, which is the sum of the cross-sectional areas A of the shaft portions 34, is 2A. Therefore, the electrical resistance between the conductive member 17 and the terminal joint member 31 in the secondary battery of the first embodiment is the electrical resistance between the conductive member 17 and the terminal joint member 31 in the secondary battery 10 of the comparative example. It is about half (half) of

  When the distance P1 from one long edge portion 14d of the lid 14 to the outer peripheral surface 34a of the shaft portion 34 in the short direction of the lid 14 is less than 4 mm, the one long edge portion of the outer insulating member 37 and the lid 14 The distance with one long edge part 14d becomes near. Similarly, when the distance P2 from the other long edge portion 14d of the lid 14 to the outer peripheral surface 34a of the shaft portion 34 in the short direction of the lid 14 is less than 4 mm, the other long edge portion of the outer insulating member 37 and the lid 14 The distance to the other long edge portion 14d becomes closer. For this reason, the thermal influence when welding the case main body 13 and the lid 14 may reach the long edge portion of the outer insulating member 37. That is, when the case 11 is welded, the long edge portion of the outer insulating member 37 may be melted or deformed. On the other hand, by setting the distances P1 and P2 to 4 mm or more, the distance between the long edge portion of the outer insulating member 37 and the long edge portion 14d of the lid 14 is sufficiently maintained. It can suppress that the heat influence at the time of welding reaches the long edge part of the outer side insulation member 37. FIG. That is, when the case 11 is welded, the long edge portion of the outer insulating member 37 can be prevented from melting or deforming.

  Similarly, when the distance Q from the short edge portion 14e of the lid 14 to the outer peripheral surface 34a of the shaft portion 34 in the longitudinal direction of the lid 14 is less than 4 mm, the short edge portion of the outer insulating member 37 and the short edge portion 14e of the lid 14 are used. , And the thermal effect when welding the case body 13 and the lid 14 may reach the short edge of the outer insulating member 37. That is, when the case 11 is welded, the short edge portion of the outer insulating member 37 may be melted or deformed. On the other hand, since the distance between the short edge portion of the outer insulating member 37 and the short edge portion 14e of the lid 14 is sufficiently maintained by setting the distance Q to 4 mm or more, the case main body 13 and the lid 14 are welded. It is possible to suppress the influence of heat on the short edge portion of the outer insulating member 37. That is, it is possible to prevent the short edge portion of the outer insulating member 37 from being melted or deformed when the case 11 is welded.

Next, effects of the first embodiment will be described.
(1-1) A distance P1 from one long edge portion 14d of the lid 14 in the short direction of the lid 14 to the outer peripheral surface 34a of the shaft portion 34 of the first rivet member 32a and the second rivet member 32b, and the lid 14 The distance P2 from the other long edge portion 14d of the lid 14 in the short direction to the outer peripheral surface 34a of the shaft portion 34 of the first rivet member 32a and the second rivet member 32b is set to 4 mm, so that the case body 13 and the lid 14 can be prevented from affecting the long edge portion of the outer insulating member 37. That is, when the case 11 is welded, the long edge portion of the outer insulating member 37 can be prevented from melting or deforming.

Further, the cross-sectional area S1, which is the sum of the cross-sectional areas A of the shaft portions 34, is obtained when the cross-sectional shape of the shaft portion 34 is a perfect circle, that is, the cross-sectional area A is ((W− (P1 + P2)) / 2) ² Since it becomes twice (S1 = 2A) in the case of π, the electrical resistance between the conductive member 17 and the terminal bonding member 31 can be reduced to about half. Therefore, a decrease in output efficiency of the secondary battery 10 can be suppressed.

  (1-2) Heat when welding the case main body 13 and the lid 14 by setting the distance Q from the short edge portion 14e of the lid 14 to the outer peripheral surface 34a of the shaft portion 34 in the longitudinal direction of the lid 14 to 4 mm. It is possible to suppress the influence from reaching the short edge portion of the outer insulating member 37. That is, it is possible to prevent the short edge portion of the outer insulating member 37 from being melted or deformed when the case 11 is welded.

  (1-3) The conductive member 17 includes an electrode connection portion 17a to which the tab group 15 is welded, and a terminal connection portion 17b joined to the first rivet member 32a and the second rivet member 32b. When the electrode connection portion 17 a and the terminal connection portion 17 b are present at the same position in the longitudinal direction of the conductive member 17, the tab group 15 is welded to the first rivet member 32 a or the second rivet member 32 b in the longitudinal direction of the conductive member 17. And welded to the same part as the joined part. For example, if a bead is formed when the first rivet member 32 a or the second rivet member 32 b is welded and the conductive member 17 is uneven, the tab group 15 may not be welded to the conductive member 17 satisfactorily. On the other hand, in the present embodiment, the electrode connection portion 17 a and the terminal connection portion 17 b do not overlap when viewed from the thickness direction of the lid 14 and exist at different positions in the longitudinal direction of the conductive member 17. For this reason, the tab group 15 can be welded and joined to a part different from the part where the first rivet member 32 a or the second rivet member 32 b is joined in the longitudinal direction of the conductive member 17. Therefore, the tab group 15 can be favorably welded to the conductive member 17.

  (1-4) The electrode terminal 16 includes two rivet members (a first rivet member 32a and a second rivet member 32b). For this reason, the electrical resistance between the conductive member 17 and the terminal joining member 31 can be easily reduced only by increasing the number of rivet members.

(Second Embodiment)
Hereinafter, a second embodiment in which the power storage device is embodied as a secondary battery will be described with reference to FIGS. Note that description of the same configuration as in the first embodiment is omitted.

  As shown in FIGS. 4 and 5, in the second embodiment, the electrode terminal 16 includes one rivet member 32 c. The rivet member 32 c has a base portion 33, a shaft portion 34, and a crimping portion 35. The cross-sectional shape of the shaft portion 34 viewed from the axial direction is an elliptical shape. The rivet member 32c is arranged such that the long axis of the shaft portion 34 is the longitudinal direction of the lid 14, and the short axis of the shaft portion 34 is the short axis of the short direction of the lid 14. Further, the caulking portion 35 has an elliptical shape similar to the cross section of the shaft portion 34 when the outer surface 14b of the lid 14 is viewed from the thickness direction. That is, the caulking portion 35 is non-circular.

  As shown in FIG. 6, the distance P <b> 1 that is the shortest distance from one long edge portion 14 d of the lid 14 to the outer peripheral surface 34 a of the shaft portion 34 in the short direction of the lid 14, and the lid 14 in the short direction of the lid 14. The distance P2 that is the shortest distance from the other long edge portion 14d to the outer peripheral surface 34a of the shaft portion 34 is set to 4 mm. As shown in FIG. 4, a distance Q that is the shortest distance from the short edge portion 14e of the lid 14 to the outer peripheral surface 34a of the shaft portion 34 of the rivet member 32c in the longitudinal direction of the lid 14 is set to 4 mm.

Next, the operation of the second embodiment will be described using a comparative example. The comparative example is a comparative example used when explaining the operation of the first embodiment.
The short axis length RS of the shaft portion 34 of the rivet member 32c of the second embodiment is W− (P1 + P2), and the long axis length RL of the shaft portion 34 satisfies RS <RL. For this reason, the cross-sectional area S2 of the shaft part 34 of the rivet member 32c of the second embodiment is larger than the cross-sectional area A of the shaft part 34 of the rivet member of the comparative example (A <S2). Therefore, the electrical resistance of the shaft portion 34 of the rivet member 32c of the second embodiment is smaller than the electrical resistance of the shaft portion 34 of the rivet member of the comparative example.

In the second embodiment, in addition to the same effects (1-2) and (1-3) as in the first embodiment, the following effects can be obtained.
(2-1) The distance P1 from one long edge portion 14d of the lid 14 in the short direction of the lid 14 to the outer peripheral surface 34a of the shaft portion 34 of the first rivet member 32a and the second rivet member 32b, and the lid 14 The distance P2 from the other long edge portion 14d of the lid 14 in the short direction to the outer peripheral surface 34a of the shaft portion 34 of the first rivet member 32a and the second rivet member 32b is set to 4 mm, so that the case body 13 and the lid 14 can be prevented from affecting the long edge portion of the outer insulating member 37. That is, when the case 11 is welded, the long edge portion of the outer insulating member 37 can be prevented from melting or deforming.

Further, the cross-sectional shape of the shaft portion 34 of the rivet member 32c is an elliptical shape in which the major axis extends in the longitudinal direction of the lid 14, and the length RS of the minor axis is W− (P1 + P2). Therefore, the cross-sectional area S2 of the shaft portion 34 of the rivet member 32c, when the sectional shape of the shaft portion 34 is true circular shape, i.e. the cross-sectional area A is ((W- (P1 + P2) ) / 2) is ² [pi Since it becomes larger than the case, the electrical resistance between the conductive member 17 and the terminal joining member 31 can be reduced. Therefore, a decrease in output efficiency of the secondary battery 10 can be suppressed.

  (2-2) When viewed from the thickness direction of the lid 14, the caulking portion 35 is non-circular, and therefore the area exposed to the outside of the case 11 as compared to the case where the caulking portion 35 is circular. Becomes larger. Therefore, the heat dissipation of the rivet member 32c can be improved.

(Third embodiment)
Hereinafter, a third embodiment in which the power storage device is embodied as a secondary battery will be described with reference to FIGS. 7 and 8. Note that description of the same configuration as in the first embodiment is omitted.

  As shown in FIGS. 7 and 8, in the third embodiment, each conductive member 17 includes a rectangular plate-like first plate portion 51 disposed along the inner surface 14 a of the lid 14, and the first plate portion 51. A third plate that connects the long plate of the first plate 51 and the long plate of the second plate 52 on the other end side in the stacking direction. Part 53. In the present embodiment, the first to third plate portions 51 to 53 are formed by bending the flat conductive member 17.

  The longitudinal directions of the first plate portion 51 and the second plate portion 52 respectively coincide with the longitudinal direction of the lid 14, and the short directions of the first plate portion 51 and the second plate portion 52 respectively coincide with the stacking direction. The dimension in the longitudinal direction of the first plate part 51 is longer than the dimension in the longitudinal direction of the second plate part 52. When viewed from the lid 14, the first plate portion 51 has a portion overlapping the second plate portion 52 and a portion extending to the short edge portion 14 e side of the lid 14 with respect to the second plate portion 52. The first plate portion 51 includes a terminal connection portion 51a in which a first rivet member 32a and a second rivet member 32b are joined to one end portion in the longitudinal direction. The second plate portion 52 is an electrode connecting portion 52a in which the entire tab group 15 is welded. When viewed from the thickness direction of the lid 14, a part of the electrode connection part 52a overlaps a part of the terminal connection part 51a.

In the third embodiment, in addition to the effects (1-1), (1-2), and (1-4) of the first embodiment, the following effects can be obtained.
(3-1) The conductive member 17 includes a first plate portion 51 disposed along the inner surface 14 a of the lid 14, a second plate portion 52 facing the first plate portion 51, a first plate portion 51, and a first plate portion 51. And a third plate portion 53 that connects the two plate portions 52. The first rivet member 32 a and the second rivet member 32 b are joined to the terminal connection portion 51 a of the first plate portion 51, and the tab group 15 is joined to the electrode connection portion 52 a of the second plate portion 52. For this reason, the tab group 15 can be favorably welded to the conductive member 17 as compared with the case where the tab group is welded and joined to the portion where the rivet member is joined in the flat conductive member.

  Further, when viewed from the thickness direction of the lid 14, the electrode connection portion 52 a is arranged at a position overlapping the terminal connection portion 51 a, so that the electrode connection portion 52 a is the other end in the longitudinal direction of the first plate portion 51. In addition to the position overlapping with the central portion and the central portion, it extends to the position overlapping with the terminal connecting portion 51a. For this reason, the dimension of the electrode connection part 52a can be increased compared with the case where the electrode connection part 52a extends only in the position which overlaps with the other end part and center part of the longitudinal direction of the 1st board part 51. FIG. Therefore, also about the tab 26 of the tab group 15 welded to the electrode connection part 52a, the dimension in the longitudinal direction of the lid | cover 14 can be increased, and the cross-sectional area of the tab 26 increases. As a result, the electrical resistance of the tab 26 can be reduced, and a decrease in output efficiency of the secondary battery 10 can be suppressed.

(Fourth embodiment)
Hereinafter, a fourth embodiment in which the power storage device is embodied as a secondary battery will be described with reference to FIGS. 9 and 10. Note that description of the same configuration as in the first embodiment is omitted.

  As shown in FIG. 9, in the fourth embodiment, the electrode terminal 16 includes three rivet members (first to third rivet members 32d to 32f). The first to third rivet members 32 d to 32 f are the same rivet member, and are arranged side by side in the longitudinal direction of the lid 14. The first rivet member 32d is disposed near the short edge portion 14e of the lid 14. The second rivet member 32e is disposed on the side opposite to the short edge portion 14e of the lid 14 with respect to the first rivet member 32d. The third rivet member 32f is disposed on the opposite side of the second rivet member 32e from the first rivet member 32d.

  As shown in FIG. 10, the distance P1 which is the shortest distance from one long edge portion 14 d of the lid 14 to the outer peripheral surface 34 a of the shaft portion 34 in the short direction of the lid 14, and the lid 14 in the short direction of the lid 14. The distance P2 that is the shortest distance from the other long edge portion 14d to the outer peripheral surface 34a of the shaft portion 34 is set to 4 mm. As shown in FIG. 9, the distance Q that is the shortest distance from the short edge portion 14e of the lid 14 to the outer peripheral surface 34a of the shaft portion 34 of the first rivet member 32d in the longitudinal direction of the lid 14 is set to 4 mm. The

  As shown in FIGS. 9 and 10, in the fourth embodiment, the terminal joining member 31 includes a rectangular plate-like first connection portion 61 disposed along the outer surface 14 b of the lid 14, and a first connection portion 61. And a third connection that connects one long edge portion of the first connection portion 61 and one long edge portion of the second connection portion 62 on the other end side in the stacking direction. Part 63. In addition, the 1st-3rd connection parts 61-63 of this embodiment are formed by bending the flat terminal joining member 31. FIG.

  The longitudinal directions of the first connecting part 61 and the second connecting part 62 respectively coincide with the longitudinal direction of the lid 14, and the lateral direction of the first connecting part 61 and the second connecting part 62 respectively coincide with the stacking direction. The dimensions in the longitudinal direction of the first to third connection parts 61 to 63 are the same. The shaft portions 34 of the first to third rivet members 32 d to 32 f penetrate the first connection portion 61. The external connection terminal 36 extends from the end opposite to the short edge portion 14e in the longitudinal direction of the second connection portion 62 toward the opposite side to the direction from the second connection portion 62 toward the first connection portion 61. Put out. That is, the external connection terminal 36 extends in a direction away from the lid 14. When viewed from the thickness direction of the lid 14, the first connection portion 61 overlaps the second connection portion 62. The external connection terminal 36 overlaps the third rivet member 32f.

Next, the operation of the fourth embodiment will be described using a comparative example. The comparative example is a comparative example used when explaining the operation of the first embodiment.
In the fourth embodiment, the electrode terminal 16 includes three rivet members (first to third rivet members 32d to 32f). For this reason, the cross-sectional area S4 that is the sum of the cross-sectional areas A of the respective shaft portions 34 is 3A. Therefore, the electrical resistance between the conductive member 17 and the terminal joint member 31 in the secondary battery 10 of the fourth embodiment is the electrical resistance between the conductive member 17 and the terminal joint member 31 in the secondary battery of the comparative example. About one third of

In the fourth embodiment, the following effects can be obtained in addition to the effects (1-2) and (1-4) of the first embodiment.
(4-1) The distance P1 from one long edge portion 14d of the lid 14 to the outer peripheral surface 34a of the shaft portion 34 of the first to third rivet members 32d to 32f in the short direction of the lid 14, and the shortness of the lid 14 By setting the distance P2 from the other long edge portion 14d of the lid 14 in the hand direction to the outer peripheral surface 34a of the shaft portion 34 of the first to third rivet members 32d to 32f to 4 mm, the case body 13 and the lid 14 It is possible to suppress the heat effect when welding the outer edge of the outer insulating member 37 from being affected. That is, when the case 11 is welded, the long edge portion of the outer insulating member 37 can be prevented from melting or deforming.

Further, the cross-sectional area S4 that is the sum of the cross-sectional areas A of the respective shaft portions 34 is obtained when the cross-sectional shape of the shaft portion 34 is a perfect circle, that is, the cross-sectional area A is ((W− (P1 + P2)) / 2) ² Since it is three times as large as π (S4 = 3A), the electrical resistance between the conductive member 17 and the terminal bonding member 31 can be reduced to about one third. Therefore, a decrease in output efficiency of the secondary battery 10 can be suppressed.

  (4-2) The terminal joining member 31 is disposed along the outer surface 14b of the lid 14 and has a plate-like first connecting portion 61 through which the shaft portion 34 of the first to third rivet members 32d to 32f passes, It has a plate-like second connection part 62 that faces the first connection part 61 and from which the external connection terminal 36 extends, and a third connection part 63 that connects the first connection part 61 and the second connection part 62. . For this reason, in the longitudinal direction of the lid 14, the degree of freedom of arrangement of the rivet member with respect to the terminal joining member 31 can be increased without changing the position of the external connection terminal 36. 1st-3rd rivet member 32d-32f) can be arrange | positioned. In this case, since the distance between the external connection terminal 36 on the positive electrode side and the external connection terminal 36 on the negative electrode side does not change, the same bus bar as the conventional one can be used.

In addition, you may change the said embodiment as follows.
○ The case body 13 may be made of stainless steel.
(Circle) You may change the thickness of the long side wall 13c and the short side wall 13d of the case main body 13 in the range of 0.5-1.0 mm, respectively.

○ The lid 14 may be made of stainless steel.
(Circle) You may change the thickness of the part which overlaps with the front end surface of the long side wall 13c and the short side wall 13d of the case main body 13 in the lid | cover 14 in the range of 1-2 mm.

The tip surfaces of the long side wall 13c and the short side wall 13d of the case main body 13 and the lid 14 may be welded by irradiating the case main body 13 with laser from the lid 14 side.
In the positive electrode 21, the positive electrode active material layer 25 may exist on one side of the positive electrode metal foil 24. Similarly, in the negative electrode 22, the negative electrode active material layer 28 may exist on one side of the negative electrode metal foil 27.

  In the first and third embodiments, the cross-sectional shape of the shaft portion 34 of the first rivet member 32a is not limited to a circular shape. Similarly, the cross-sectional shape of the shaft portion 34 of the second rivet member 32b is not limited to a circular shape. However, the cross-sectional areas S1 and S3, which are the sum of the cross-sectional areas of the shaft portions 34 of the first rivet member 32a and the second rivet member 32b, have a cross-sectional shape such that A <S1, S3.

  In the fourth embodiment, the cross-sectional shape of the shaft portion 34 of the first rivet member 32d is not limited to a circular shape. Similarly, the cross-sectional shape of the shaft portion 34 of the second rivet member 32e is not limited to a circular shape. Similarly, the cross-sectional shape of the shaft portion 34 of the third rivet member 32f is not limited to a circular shape. However, it is set as the cross-sectional shape in which the cross-sectional area S4 which is the sum total of the cross-sectional area of the axial part 34 of the 1st-3rd rivet members 32d-32f becomes A <S4.

  In the second embodiment, the shape of the caulking portion 35 of the rivet member 32c may be, for example, a substantially rectangular shape with rounded corners as shown in FIG. The cross-sectional shape of the shaft portion 34 of the rivet member 32 c may be rectangular as in the caulking portion 35. Similarly, in the first embodiment, the third embodiment, and the fourth embodiment, the shape of the crimping portion 35 and the cross-sectional shape of the shaft portion 34 may be substantially rectangular.

  In the first to fourth embodiments, the distance P1 that is the shortest distance from one long edge portion 14d of the lid 14 to the outer peripheral surface 34a of the shaft portion 34 of the rivet member in the short direction of the lid 14 is 4 mm or more. If so, it may be changed as appropriate. Similarly, the distance P2 that is the shortest distance from the other long edge portion 14d of the lid 14 to the outer peripheral surface 34a of the shaft portion 34 of the rivet member in the short direction of the lid 14 may be appropriately changed as long as it is 4 mm or more. . Further, the distance P1 and the distance P2 may be different. However, it is assumed that the terminal joining member 31 and the crimping portion 35 of the rivet member can be arranged in the short direction of the lid 14.

  In the first to fourth embodiments, if the distance Q, which is the shortest distance from the short edge portion 14e of the lid 14 in the longitudinal direction of the lid 14 to the outer peripheral surface 34a of the shaft portion 34 of the rivet member, is 4 mm or more. You may change suitably. However, it is assumed that at least the terminal joining member 31 of each pole and the crimping portion 35 of the rivet member can be arranged in the longitudinal direction of the lid 14.

In the first embodiment, the number of rivet members included in the electrode terminal 16 may be three or more.
In the second embodiment, the number of rivet members 32c included in the electrode terminal 16 may be two or more.

In the third embodiment, the number of rivet members provided in the electrode terminal 16 may be three or more.
In the fourth embodiment, the number of rivet members included in the electrode terminal 16 may be two, or four or more.

In the first and second embodiments, the electrode connection portion 17 a and the terminal connection portion 17 b may overlap when viewed from the thickness direction of the lid 14.
In the first, second, and fourth embodiments, a part of the tab group 15 along the longitudinal direction of the conductive member 17 may be welded to the lower surface of the conductive member 17. A portion of the tab group 15 that is not welded to the conductive member 17 may overlap the terminal connection portion 17b.

In the first to fourth embodiments, the shape of the caulking portion 35 viewed from the thickness direction of the lid 14 may not be the same as the cross-sectional shape of the shaft portion 34.
Next, the technical idea that can be grasped from the first embodiment will be added below.

(A) An electrode assembly having a tab group in which electrodes are stacked and tabs having a shape protruding from the electrodes are stacked, a case main body that accommodates the electrode assembly, and an opening of the case main body are closed. A case having a rectangular plate-like lid welded to the case body, a plate-like terminal joining member disposed along an outer surface of the lid, and a rivet member electrically connected to the terminal joining member. An electrode terminal, a conductive member that electrically connects the tab group and the electrode terminal, an insulating member that is disposed between the terminal bonding member and the lid, and insulates the terminal bonding member and the lid And the rivet member includes a shaft portion that penetrates the lid and the terminal joining member, and a caulking portion that is caulked outside the case, wherein the shaft portion of the lid In the center in the short direction The width of the lid in the short direction is W, the distance from one long edge portion of the lid to the outer peripheral surface of the shaft portion in the short direction of the lid is P1, and the other length of the lid is when the distance from the edge to the outer peripheral surface of the shaft portion and the P2, the cross-sectional area of the shank, ((W- (P1 + P2 )) / 2) is ² [pi, the distance P1 and the distance P2 is Each of the power storage devices is 4 mm or more and includes a plurality of the rivet members in the longitudinal direction of the lid.

DESCRIPTION OF SYMBOLS 10 ... Secondary battery as an electrical storage device, 11 ... Case, 12 ... Electrode assembly, 13 ... Case main body, 13a ... Opening part, 14 ... Cover, 14a ... Inner surface, 14b ... Outer surface, 14d ... Long edge part, 14e ... Short edge portion, 15 ... tab group, 16 ... electrode terminal, 17 ... conductive member, 17a ... electrode connection portion, 17b ... terminal connection portion, 21 ... positive electrode as electrode, 22 ... negative electrode as electrode, 26 ... tab 31 ... Terminal joining member, 32c ... Rivet member, 34 ... Shaft part, 34a ... Outer peripheral surface, 35 ... Caulking part, 36 ... External connection terminal, 37 ... Outer insulating member as insulating member, 51 ... First plate part, 51a ... terminal connection part, 52 ... second plate part, 52a ... electrode connection part, 53 ... third plate part, 61 ... first connection part, 62 ... second connection part, 63 ... third connection part, P1, P2 , Q: distance, S1-S4: cross-sectional area.

Claims (7)

An electrode assembly having a tab group in which electrodes are stacked and tabs having shapes protruding from the electrodes are stacked;
A case body containing the electrode assembly, and a case having a rectangular plate-like lid welded to the case body in a state where the opening of the case body is closed;
A plate-like terminal joining member disposed along the outer surface of the lid, and an electrode terminal having a rivet member electrically connected to the terminal joining member;
A conductive member that electrically connects the tab group and the electrode terminal;
A plate-like insulating member that is disposed between the terminal joining member and the lid, and insulates the terminal joining member and the lid;
With
The rivet member is a power storage device having a shaft portion that penetrates the lid and the terminal joining member, and a caulking portion that is caulked outside the case,
The dimension in the short direction of the lid is W, the distance from one long edge portion of the lid to the outer peripheral surface of the shaft portion in the short direction of the lid is P1, and from the other long edge portion of the lid When the distance to the outer peripheral surface of the shaft portion is P2,
Sectional area of the shank, ((W- (P1 + P2 )) / 2) 2 greater than [pi,
Each of the distance P1 and the distance P2 is 4 mm or more.   The power storage device according to claim 1, wherein the distance Q is 4 mm or more, where Q is a distance from a short edge portion of the lid in the longitudinal direction of the lid to the outer peripheral surface of the shaft portion.   The power storage device according to claim 1, wherein a plurality of the rivet members are arranged in a longitudinal direction of the lid.   The conductive member has a rectangular plate shape extending in the longitudinal direction of the lid, and has an electrode connection portion to which the tab group is welded, and a terminal connection portion to which the rivet member is joined, and the electrode connection portion The power storage device according to any one of claims 1 to 3, wherein the terminal connection portion and the terminal connection portion are present at different positions in a longitudinal direction of the conductive member. The conductive member is
A first plate portion disposed along the inner surface of the lid and having a terminal connection portion to which the rivet member is joined;
A second plate portion facing the first plate portion and having an electrode connection portion to which the tab group is welded;
A third plate portion connecting the first plate portion and the second plate portion,
4. The power storage device according to claim 1, wherein when viewed from the thickness direction of the lid, a part of the electrode connection part overlaps at least a part of the terminal connection part. The electrode terminal includes an external connection terminal,
The terminal joining member is
A plate-like first connecting portion disposed along the outer surface of the lid and through which the shaft portion of the rivet member passes;
A plate-like second connection portion facing the first connection portion;
A third connecting portion connecting the first connecting portion and the second connecting portion;
With
The said external connection terminal is extended from the said 2nd connection part toward the opposite side to the direction which goes to the said 1st connection part from the said 2nd connection part. Power storage device.   The power storage device according to any one of claims 1 to 6, wherein the caulking portion is non-circular when viewed from a thickness direction of the lid.