JP2012243405A - Rectangular secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a rectangular secondary battery in which there is no possibility that a joint is deformed or short-circuited to the electrode terminal of an adjoining battery, and which can be handled easily and can down-size the battery pack.SOLUTION: In a rectangular secondary battery 1, electrode terminals 10 and 20 are supported on a lid 3 of a battery case 2 via insulation members 30 and 40. The electrode terminals 10 and 20 of the rectangular secondary battery 1 have joints 13 and 23 extending in parallel with the lid 3 while facing the top face thereof. The insulation members 30 and 40 have insulation pedestals 32 and 42 interposed between the top face of the lid 3 and the joints 13 and 23 and supporting the joints 13 and 23.

Description

  The present invention relates to a prismatic secondary battery in which an electrode terminal is supported by an insulating member on a lid of a battery case.

  As Conventional Example 1, a rectangular plate-shaped metal lid in which a power generating body is housed in a bottomed square box-shaped metal battery case having a rectangular opening at one end, and the opening is fixed to the battery case. In a rectangular secondary battery hermetically sealed by a member, one end (lower end) of a metal terminal plate (current collector plate) is conductively connected to the power generator in the battery case, and the other end (upper end) is a lid member. The through-hole formed in is penetrated in a non-contact state with the lid member and protrudes straight outward (upward) of the lid member, and the through-hole is molded into the lid member by insert molding including the other end side of the terminal plate What was sealed by the insulating mold part by a synthetic resin is known (for example, patent document 1, 2).

  As Conventional Example 2, the upper end portion of the terminal plate protruding outward from the lid member is bent to the side of the battery adjacent to the side and protruded to the side of the lid member, and the terminal plate of the adjacent rectangular secondary battery is There has been proposed a battery in which adjacent prismatic secondary batteries are conductively connected by superimposing protruding bent portions on each other (for example, Patent Document 3).

JP 2008-84559 A JP 2009-104793 A JP 2008-166091 A

  In the rectangular secondary battery of Conventional Example 1, since the terminal plate protrudes straight above the lid member, in the battery pack formed by electrically connecting the protruding end portions of the terminal plates of the plurality of rectangular secondary batteries, A large space is required above the lid member, which hinders downsizing of the battery pack. This is a particularly serious problem in relation to the vehicle height when the battery pack is arranged under the vehicle body floor in a hybrid vehicle or an electric vehicle.

  In the prismatic secondary battery of Conventional Example 2, the upper end portion of the terminal plate is bent sideways, so that it is possible to reduce the space above that of Conventional Example 1, but the bent portion at the tip of the terminal plate. Protrudes to the side of the lid member, that is, the bent part at the tip of the terminal plate protrudes from the outer shape of the secondary battery to the side, so that the terminal plate can be used for storage, transportation and battery pack assembly processes. There was a risk of deformation. For this reason, attention is required for handling, which hinders improvement in efficiency of various operations. In addition, the terminal plate must be prevented from being deformed, the packaging material is enlarged, and the storage space for the secondary battery is prevented from being reduced.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a prismatic secondary battery that is easy to handle during storage, transportation, and the like, and that allows the battery pack to be miniaturized. There is.

  In order to solve the above-described problems, a prismatic secondary battery according to the present invention is a prismatic secondary battery in which an electrode terminal is supported on a lid of a battery case via an insulating member, and the electrode terminal is disposed on an upper surface of the lid. It has the junction part which opposes and extends in parallel, and the insulating member is interposed between the upper surface of the lid and the junction part, and has an insulating pedestal part which supports the junction part.

  According to the prismatic secondary battery of the present invention, there is no fear that the joint portion is deformed during storage or transportation, the handling is easy, and the whole can be miniaturized when a battery pack is obtained. Problems, configurations, and effects other than those described above will be clarified by the following description of the embodiments.

1 is an overall perspective view of a prismatic secondary battery according to a first embodiment. The disassembled perspective view of the square secondary battery shown in FIG. The perspective view which expands and shows the principal part of the square secondary battery shown in FIG. The figure which shows the cross section along line III-III of FIG. The figure corresponded in the cross section along line III-III of FIG. 3 which shows the modification in 1st Embodiment. The whole perspective view of the square secondary battery concerning a 2nd embodiment. The perspective view which expands and shows the principal part of the square secondary battery shown in FIG. The figure which shows the cross section along line VII-VII of FIG. The whole perspective view of the square secondary battery concerning a 3rd embodiment. FIG. 10A is an enlarged perspective view showing the main part of FIG. 9, and FIG. 10B is a view showing a cross section taken along line XX of FIG. 10A. FIG. 11A is a perspective view showing an enlarged main part of a modification of the third embodiment, and FIG. 11B is a view showing a cross section taken along line XI-XI in FIG.

[First Embodiment]
Next, the prismatic secondary battery according to the present embodiment will be described with reference to FIGS.

  1 is an overall perspective view of a prismatic secondary battery according to the present embodiment, FIG. 2 is an exploded view of FIG. 1, FIG. 3 is an enlarged view of the main part of FIG. 2, and FIG. FIG. 3 is a diagram showing a cross section taken along line III-III of FIG.

  A rectangular secondary battery 1 according to the present embodiment is a lithium ion secondary battery used as a driving power source for an electric vehicle or a hybrid vehicle. As shown in FIG. 1, the rectangular secondary battery 1 has a bottomed square box-shaped battery case 2 having a rectangular opening 2 </ b> A, and a rectangular plate-shaped lid 3 that closes the opening 2 </ b> A of the battery case 2. doing. The battery case 2 has a shape in which the depth dimension is formed larger than the dimension of the short side of the opening 2A by deep drawing. The lid body 3 is provided with an electrolyte inlet 7 that is closed by a positive electrode terminal 10, a negative electrode terminal 20, a gas discharge valve 6, and a liquid injection stopper 8.

  Inside the battery case 2, the electrode group 4 shown in FIG. 2 is accommodated in an insulating sheet 5. The battery case 2 and the lid 3 are made of a metal material, and the lid 3 is fixed to the opening 2A of the battery case 2 by welding and hermetically sealed.

  The electrode group 4 has a positive electrode composed of a positive electrode metal foil composed of a metal foil such as aluminum and a positive electrode mixture layer applied to the front and back surfaces of the positive electrode metal foil, although not shown in the drawing, and copper A negative electrode metal foil composed of a metal thin film such as, and a negative electrode composed of a negative electrode mixture layer applied to the front and back surfaces of the negative electrode metal foil, and is formed of a polyethylene resin between the positive electrode and the negative electrode It is configured by winding flatly or laminating sandwiched porous separators having insulation properties.

  The electrode group 4 is a power source of the battery, and has a structure in which charging and discharging are performed as lithium ions move between the positive electrode and the negative electrode. In the electrode group 4, a positive electrode current collector exposed surface 4a is formed on one side in the winding axis direction, and a negative electrode current collector exposed surface 4b is formed on the other side in the winding axis direction. The current collectors 11 and 21 of the positive electrode terminal 10 and the negative electrode terminal 20 are welded to the positive electrode current collector exposed surface 4 a and the negative electrode current collector exposed surface 4 b of the electrode group 4.

  The positive electrode terminal 10 and the negative electrode terminal 20 are supported by the lid body 3 via insulating members 30 and 40. As shown in FIG. 2, openings 3 </ b> A and 3 </ b> B through which the positive terminal 10 and the negative terminal 20 are inserted are formed at both ends in the long side direction of the lid 3. The positive electrode terminal 10 and the negative electrode terminal 20 are integrally fixed to and supported by the lid member 3 by the insulating members 30 and 40 while being inserted through the openings 3A and 3B of the lid member 3 by insert molding.

  The positive electrode terminal 10 and the negative electrode terminal 20 are formed by bending a metal plate material such as aluminum or copper, and have a bilaterally symmetric shape. The positive electrode terminal 10 and the negative electrode terminal 20 are connected to the positive electrode current collector exposed surface 4a and the negative electrode current collector exposed surface 4b of the electrode group 4 shown in FIG. And holding portions 12 and 22 that are continuously formed at the upper end portions of the current collecting portions 11 and 21 and are held by the insulating members 30 and 40 while being inserted into the openings 3A and 3B of the lid 3. The joint portions 13 and 23 are formed continuously from the portions 12 and 22 and exposed on the upper surface of the lid 3.

  The current collectors 11, 21 and the holding parts 12, 22 have substantially the same width, the width direction is parallel to the long side direction of the lid 3, and the depth direction in the battery case 2 from the lid 3 It is formed so as to extend.

  The holding portions 12 and 22 include lower surface portions 12a and 22a arranged in parallel to face the lower surface of the lid 3, upper surface portions 12c and 22c arranged in parallel to face the upper surface of the lid 3, and a lid. Longitudinal surface portions 12b and 22b that pass through the openings 3A and 3B of the body 3 and extend between the lower surface portions 12a and 22a and the upper surface portions 12c and 22c are provided.

  As shown in FIG. 4, the holding portions 12 and 22 have a shape bent in a step shape in which the upper surface portions 12 c and 22 c and the lower surface portions 12 a and 22 a extend from the vertical surface portions 12 b and 22 b in directions away from each other. ing. Specifically, the lower surface portions 12a and 22a are bent at the upper end portions of the current collecting portions 11 and 21, and extend in parallel with the lower surface of the lid body 3 from one side to the other side in the short side direction of the lid body 3. The vertical surface portions 12b and 22b are bent toward the lid body 3 at positions corresponding to the opening portions 3A and 3B continuously from the lower surface portions 12a and 22a, and pass through the opening portions 3A and 3B. The upper surface portions 12c and 22c are bent toward the other side in the short side direction of the lid body 3 at the upper ends of the vertical surface portions 12b and 22b, and extend parallel to the upper surface of the lid body 3. ing.

  FIG. 5 is a diagram illustrating a modified example of the holding unit, and corresponds to FIG. 4. In the case of this modification, the holding portions 12 and 22 have a shape in which the upper surface portions 12c and 22c and the lower surface portions 12a and 22a are bent in a U-shaped cross section extending in the same direction from the vertical surface portions 12b and 22b. Yes. That is, the upper surface portions 12 c and 22 c are bent again toward one side in the short side direction of the lid body 3 at the upper ends of the vertical surface portions 12 b and 22 b, and extend parallel to the upper surface of the lid body 3.

  As shown in FIG. 2, the joint portions 13 and 23 have a flat plate shape extending along the long side direction of the lid 3. As shown in FIGS. 3 and 4, the joint portions 13 and 23 extend in parallel to face the upper surface of the lid 3, and the joint surface that is the upper surface of the joint portions 13 and 23 is the holding portion 12 or 22. It arrange | positions so that it may become flush with the upper surface parts 12c and 22c.

  The joint portions 13 and 23 have a shape that is expanded stepwise in the short side direction of the lid 3 than the upper surface portions 12c and 22c of the holding portions 12 and 22, and the joint surfaces are from the upper surface portions 12c and 22c. Is also getting wider. Specifically, the left-right width Lw, which is the length in the same direction as the long side direction of the lid 3, is larger than the length in the short side direction of the lid 3, and the length in the same direction as the short side direction of the lid 3. The front-rear width Ld is larger than the length of the upper surface portions 12c and 22c in the same direction and smaller than the length of the lid 3 in the short side direction.

  Thus, since the joining parts 13 and 23 have the joint surface of the area larger than the upper surface parts 12c and 22c on the upper surface of the joining parts 13 and 23, a wide contact area can be ensured and it is favorable. Can be obtained. Moreover, since the front-rear width Ld of the joint portions 13 and 23 is formed to be smaller than the length in the short side direction of the lid 3, it is possible to prevent the terminals from contacting each other among the plurality of rectangular secondary batteries 1. . Moreover, it becomes possible to prevent the lid 3 from being an obstacle when welding the lid 3 to the battery case 2 and facilitate the welding operation of the lid 3.

  The insulating members 30, 40 are connected to the joint portions 13, 23 from the front-rear width that is equal to or greater than the front-rear width Ld of the joint portions 13, 23 and less than the width in the short side direction of the lid 3. It has a width that is slightly larger than the length over the range. The insulating members 30 and 40 are interposed between the sealing fixing portions 31 and 41 that seal the openings 3A and 3B and fix the holding portions 12 and 22, and the upper surface of the lid 3 and the joint portions 13 and 23. Thus, the insulating bases 32 and 42 that support the joints 13 and 23 on the upper surface of the lid 3 are configured.

  The sealing fixing portions 31, 41 are larger than the front-rear width Hd and the left-right width of the openings 3A, 3B of the lid 3, and as shown in FIG. 4 or 5, the upper surface portions 12c, 22c of the holding portions 12, 22 are used. And a thickness that is interposed between the lower surface portions 12a and 22a. The holding portions 12 and 22 are such that the lower surfaces of the upper surface portions 12c and 22c are in contact with or immersed in the upper surfaces of the sealing fixing portions 31 and 41, and the upper surfaces of the upper surface portions 12c and 22c are upward from the sealing fixing portions 31 and 41. Exposed. The upper surfaces of the lower surface portions 12 a and 22 a are in contact with or immersed in the lower surfaces of the sealing fixing portions 31 and 41.

  The insulating pedestals 32 and 42 are formed integrally with the sealing fixing portions 31 and 41 so as to extend from the sealing fixing portions 31 and 41 toward the center side in the long side direction of the lid 3. The insulating pedestal portions 32 and 42 extend along the upper surface of the lid 3 at the same height as the sealing fixing portions 31 and 41, and have a dimension shape that is the same as or slightly larger than the size of the joint portions 13 and 23. doing. The joint portions 13 and 23 are supported on the upper surfaces of the insulating pedestal portions 32 and 42.

  Similar to the holding portions 12 and 22, the joining portions 13 and 23 are joined to the upper surfaces of the insulating pedestal portions 32 and 42, and the lower surfaces of the joining portions 13 and 23 are brought into contact with or submerged into the upper surfaces of the joining portions 13 and 23. The surface is disposed above the insulating pedestals 32 and 42. For example, when a bus bar is placed on the joints 13 and 23, the joints 13 and 23 can be reliably brought into contact with the bus bar.

  According to the prismatic secondary battery 1 having the above-described configuration, the positive electrode terminal 10 and the negative electrode terminal 20 have the joint portions 13 and 23 that extend in parallel to face the upper surface of the lid 3, and the insulating members 30 and 40 are provided. Since it has the insulation base parts 32 and 42 which are interposed between the upper surface of the cover body 3 and the junction parts 13 and 23, and support the junction parts 13 and 23, the junction parts 13 and 23 are at the time of storage or transportation. There is no risk of deformation. Therefore, it can be easily handled as a single battery, and the efficiency of various operations can be improved. Moreover, the treatment for preventing the deformation of the joint portions 13 and 23 is not required, the packaging material is not enlarged, and the storage space for the prismatic secondary battery 1 can be reduced.

  In addition, when the battery pack is configured by electrically connecting the joint portions 13 and 23 of the plurality of rectangular secondary batteries 1 with the bus bar, the space required above the lid 3 can be reduced, and the overall height of the battery pack can be reduced. Can be reduced, and the entire battery pack can be reduced in size.

  According to the prismatic secondary battery 1 having the above configuration, the joint portions 13 and 23 extend from the holding portions 12 and 22 toward the center side in the long side direction of the lid body 3 so as to be accommodated on the upper surface of the lid body 3. Since it has a flat plate shape, it is possible to secure a wider contact area of the joint surface, which is the upper surface of the joint portions 13 and 23, and to obtain a good conductive connection.

  According to the prismatic secondary battery 1 having the above configuration, the holding portions 12 and 22 have a step shape or a shape bent in a U-shaped cross section, and an upper surface portion on the upper surface of the sealing fixing portions 31 and 41. Since the lower surfaces of 12c and 22c are in contact with or submerged and the upper surfaces of the lower surface portions 12a and 22a are in contact with or submerged in the lower surfaces of the sealing fixing portions 31 and 41, the positive terminal 10 and The negative electrode terminal 20 can be reliably held.

  In particular, in the modification shown in FIG. 5, since the holding portions 12 and 22 are bent in a U-shaped cross section and are formed so as to sandwich the insulating members 30 and 40, the positive terminal with respect to the insulating members 30 and 40. 10 and the negative electrode terminal 20 can be supported and fixed with high bonding strength.

  Therefore, for example, when a force in the short side direction of the lid body 3 acts on the positive electrode terminal 10 and the negative electrode terminal 20 due to vibration or the like, the force is applied to the upper surfaces of the holding portions 12 and 22 in addition to the vertical surface portions 12b and 22b. The portions 12c and 22c and the lower surface portions 12a and 22a can also be received and can exhibit high durability against vibration and the like.

  In addition, since the holding portions 12 and 22 have a step shape or a shape that is bent in a U-shaped cross section, it is difficult to form a gap between the insulating members 30 and 40, and the electrolytic solution is generated from the gap. And gas can be prevented from leaking, and the sealed state can be reliably maintained.

  Further, since the holding portions 12 and 22 are connected to the current collecting portions 11 and 21 and the joint portions 13 and 23 by the shortest distance by the vertical surface portions 12b and 22b extending in a straight line, the distance is short, Resistance can be reduced.

[Second Embodiment]
Next, a second embodiment will be described with reference to FIGS. 6 is an overall perspective view of the prismatic secondary battery according to the present embodiment, FIG. 7 is an enlarged perspective view of the main part of the prismatic secondary battery shown in FIG. 6, and FIG. It is a figure which shows the cross section along the -V line. The same components as those in the first embodiment described above are denoted by the same reference numerals, and detailed description thereof is omitted.

  What is characteristic in the present embodiment is that a fastening member attaching portion 60 for attaching the fastening member 50 to the positive electrode terminal 10 and the negative electrode terminal 20 in a detachable manner is provided. The fastening member mounting portion 60 is provided in the joint portions 13 and 23 of the positive electrode terminal 10 and the negative electrode terminal 20, and the notches 14 and 24 into which the shaft portion 51 of the fastening member 50 can be inserted, and the joint portions 13 and 23 are insulated. It is comprised between the base parts 32 and 42, and is comprised by the engaging parts 33 and 43 which engage the head 52 of the fastening member 50 so that engagement / disengagement is possible.

  The fastening member 50 is, for example, for fastening an external connection terminal of another device (not shown), a bus bar of a battery pack, and the like to be conductively connected to the positive electrode terminal 10 and the negative electrode terminal 20. The fastening member 50 includes a shaft portion 51 having a male screw, and a head portion 52 that is enlarged at one end portion of the shaft portion 51 through a step. The diameter of the shaft portion 51 is smaller than the front-rear width Ld (see FIG. 3) of the joint portions 13 and 23, and the head portion 52 has a rectangular flat plate shape having a predetermined plate thickness.

  The cutout portion 14 of the joint portion 13 of the positive electrode terminal 10 is formed by cutting out from the end edge portion on one side in the short side direction of the lid 3 of the joint portion 13 toward the other side in the short side direction. In the present embodiment, the cutout portion 14 is joined when viewed from the holding portion 12 side of the joint portion 13 toward the center side in the long side direction of the lid body 3, that is, standing on the base end side of the joint portion 13. When the front end side of the part 13 is viewed, a notch is formed from the rear end edge portion located on the right side in the short side direction of the lid 3 toward the front end edge portion located on the left side in the short side direction.

  On the other hand, the cutout portion 24 of the joint portion 23 of the negative electrode terminal 20 is formed by cutting out from the end portion on the other side in the short side direction of the lid 3 of the joint portion 23 toward one side in the short side direction. . The notch 24 is viewed from the holding part 22 side of the joint part 23 toward the central side in the long side direction of the lid 3, that is, standing at the base end side of the joint part 23, the distal end of the joint part 23. When viewed from the side, a notch is formed from the front end edge portion located on the right side in the short side direction of the lid 3 toward the rear end edge portion located on the left side in the short side direction.

  These notches 14, 24 can be inserted through the shaft 51 of the fastening member 50, and can be arranged at a notch width narrower than the head 52, and the shaft 51 can be disposed at the center in the short side direction of the lid 3. It has a notch depth.

  The engaging portion 33 on the positive electrode terminal 10 side is an edge portion on one side in the short side direction of the lid 3 of the insulating base portion 32 in the same direction as the notch direction of the notch portion 14 at a position below the notch portion 14. Is formed in a groove shape toward the other side in the short side direction. On the other hand, the engaging portion 43 on the negative electrode terminal 20 side is an end on the other side in the short side direction of the lid 3 of the insulating base 42 in the same direction as the notch direction of the notch 24 at a position below the notch 24. It is formed in a groove shape from the edge toward one side in the short side direction. These engaging portions 33 and 43 have a pair of facing surfaces that face the sides parallel to each other of the head 52 in a state where the head 52 is engaged.

  The fastening member 50 can be engaged by inserting the head portion 52 into the engaging portions 33 and 43 from the notched side of the notched portions 14 and 24, and the shaft portion 51 projects vertically from the lid body 3. And it attaches in the state which controlled the rotation of the fastening member 50 around the central axis. And it can be fastened by screwing and tightening a nut (not shown) to the shaft portion 51, and for example, a bus bar or the like can be electrically connected to the positive terminal 10 and the negative terminal 20.

  According to the prismatic secondary battery 1 having the above-described configuration, the fastening member 50 can be attached to the positive electrode terminal 10 and the negative electrode terminal 20, and the work of conducting the conductive connection to the positive electrode terminal 10 and the negative electrode terminal 20 and the work of cutting the connection are performed. Simplification is achieved. And since the fastening member 50 can be attached to and detached from the positive electrode terminal 10 and the negative electrode terminal 20, two types of methods, a method using the fastening member 50 and a method not using it, can be selected according to the situation, and the application range of the square secondary battery can be selected. Can be spread. Also, the fastening member 50 can be easily replaced. For example, the specification of the fastening member 50 can be changed quickly and arbitrarily according to the customer's request, such as changing the shaft portion 51 from M4 to M5. Can do.

  And in this Embodiment, when the notch 14 of the junction part 13 of the positive electrode terminal 10 is seen toward the long side direction center side of the cover body 3 from the holding | maintenance part 12 side of the junction part 13, ie, joining. When standing at the base end side of the portion 13 and looking at the front end side of the joint portion 13, from the rear end edge portion located on the right side in the short side direction of the lid body 3 toward the front end edge portion located on the left side in the short side direction. Notches are formed. The notch 24 is viewed from the holding part 22 side of the joint part 23 toward the central side in the long side direction of the lid 3, that is, standing at the base end side of the joint part 23, and the distal end of the joint part 13. When viewed from the side, a notch is formed from the front end edge portion located on the right side in the short side direction of the lid 3 toward the rear end edge portion located on the left side in the short side direction.

  Therefore, when the rotational tightening torque T of the fastening member 50 acts on the joint portions 13 and 23 and the joint portions 13 and 23 are deformed, the direction in which the notch widths of the notch portions 14 and 24 are shortened, in other words, The open ends of the notches 14 and 24 can be deformed in the closing direction. Therefore, when the joint portions 13 and 23 are deformed by the rotational tightening torque T, the open end side of the notches 14 and 24 is prevented from opening and the head 52 is prevented from coming out of the engaging portions 33 and 43, and the fastening member 50. Can be prevented from coming off from the fastening member mounting portion 60.

[Third Embodiment]
Next, a third embodiment will be described with reference to FIGS. 9 is an overall perspective view of the prismatic secondary battery according to the present embodiment, FIG. 10A is an enlarged perspective view of the main part of the prismatic secondary battery shown in FIG. 9, and FIG. 10B. FIG. 11 is a cross-sectional view taken along the line XX in FIG. 10A, and FIG. 11A is an enlarged perspective view showing a main part of a modification of the present embodiment, FIG. 11B is a diagram showing a state where the bus bar is attached in a cross section taken along line XI-XI in FIG. The same components as those in the first embodiment described above are denoted by the same reference numerals, and detailed description thereof is omitted.

  What is characteristic in the present embodiment is that the bus bar 70 is positioned with respect to the joint portions 13 and 23 when the positive electrode terminal 10 and the negative electrode terminal 20 of the rectangular secondary battery adjacent to each other in the battery pack are connected by the bus bar. In other words, the structure can be welded.

  For example, in the prismatic secondary battery 1 shown in FIG. 9, projection welding projections 15 and 25 are formed on the upper surfaces of the joints 13 and 23 so as to protrude by embossing or half-piercing. In the present embodiment, two pieces are provided at predetermined intervals in the long side direction of the lid 3.

  As shown in FIG. 10A, the bus bar 70 has a strip shape extending substantially the same width as the left and right widths of the joint portions 13 and 23, and the protrusion portions 15 and 25 are inserted on the lower surface. A recessed portion 71 is formed.

  The bus bar 70 and the joint portions 13 and 23 are welded and connected by projection welding. The bus bar 70 is approached from above the joints 13 and 23, and the protrusions 15 and 25 of the joints 13 and 23 are inserted into the recesses 71 of the bus bar 70. Thereby, the bus bar 70 can be positioned with respect to the joint parts 13 and 23. A gap is formed between the upper surfaces of the joint portions 13 and 23 and the lower surface of the bus bar 70.

  Projection welding is performed in such a positioning state. In projection welding, the current at the time of resistance welding is concentrated at the contact points between the projections 15 and 25 and the recess 71 to generate heat, thereby melting and welding the projections 15 and 25 and the recess 71. Therefore, it can weld in the state which positioned the bus bar 70 with respect to the junction parts 13 and 23, and welding work can be simplified. Projection welding can be performed in a short time and at low cost. Therefore, the manufacturing cost of the battery pack can be reduced.

  Further, laser welding may be used instead of projection welding. In the case of laser welding, as shown in FIG. 11, a through hole 72 into which the protrusion 25 is fitted is formed in the bus bar 70.

  In order to laser weld the bus bar 70 and the joints 13 and 23, the bus bar 70 is approached from above the joints 13 and 23, and the protrusions 15 and 25 of the joints 13 and 23 are fitted into the through holes 72 of the bus bar 70. Combine. Then, the bus bar 70 is placed on the upper surface of the joint portion 13, and the upper surfaces of the joint portions 13 and 23 and the lower surface of the bus bar 70 are brought into contact with each other. Thereby, the bus bar 70 can be positioned with respect to the joint parts 13 and 23.

  Laser welding is performed in such a positioning state. In laser welding, welding is performed by irradiating laser on the boundary between the protrusions 15 and 25 and the through hole 72 from above the bus bar 70. Therefore, it can weld in the state which positioned the bus bar 70 with respect to the junction parts 13 and 23, and welding work can be simplified.

  The present invention is not limited to the embodiments described above, and various design changes can be made without departing from the spirit of the present invention described in the claims. For example, the above-described embodiment has been described in detail for easy understanding of the present invention, and is not necessarily limited to one having all the configurations described. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. . Furthermore, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment. For example, in each of the above-described embodiments, the case where the square secondary battery is a lithium ion secondary battery has been described as an example, but another secondary battery such as a lithium polymer secondary battery may be used.

DESCRIPTION OF SYMBOLS 1 Square secondary battery 2 Battery case 3 Lid 4 Electrode group 10 Positive terminal 12, 22 Holding part 13, 23 Joint part 20 Negative terminal 30, 40 Insulating member 32, 42 Insulating base part

Claims (10)

A prismatic secondary battery in which an electrode terminal is supported via an insulating member on a lid of a battery case,
The electrode terminal has a joint extending in parallel to face the upper surface of the lid,
The prismatic secondary battery, wherein the insulating member includes an insulating pedestal portion that is interposed between an upper surface of the lid and the joint portion and supports the joint portion.   The electrode terminal has a holding portion that is formed continuously with the joint portion and is held by the insulating member in a state of being inserted into the opening of the lid, and the holding portion is a lower surface of the lid. A lower surface portion arranged in parallel to face the upper surface, an upper surface portion arranged in parallel to face the upper surface of the lid body, and between the lower surface portion and the upper surface portion through the opening of the lid body The prismatic secondary battery according to claim 1, further comprising a vertical surface portion for connecting the two.   3. The prismatic secondary battery according to claim 2, wherein the holding portion has a shape bent in a step shape in which the upper surface portion and the lower surface portion extend in a direction away from the vertical surface portion.   3. The prismatic secondary battery according to claim 2, wherein the holding portion has a shape in which the upper surface portion and the lower surface portion are bent in a U-shaped cross section extending in the same direction from the vertical surface portion. The lid is made of a rectangular plate-shaped member,
The prismatic secondary battery according to any one of claims 1 to 4, wherein the joint portion has a flat plate shape extending along a long side direction of the lid.   The prismatic secondary battery according to claim 5, wherein the joint portion has a joint surface having an area larger than that of the upper surface portion of the holding portion on an upper surface of the joint portion.   The joint portion has a length in the same direction as the long side direction of the lid body that is larger than a length in the short side direction of the lid body, and a length in the same direction as the short side direction of the lid body. The prismatic secondary battery according to claim 6, wherein the prismatic secondary battery has a shape dimension that is larger than a length in the same direction and smaller than a length in a short side direction of the lid.   The prismatic secondary battery according to any one of claims 1 to 7, further comprising a fastening member attaching portion for detachably attaching a fastening member to the electrode terminal. The fastening member has a shaft portion and a head portion,
The fastening member attaching portion is provided between the joint portion and the insulating pedestal portion, and a head portion of the fastening member provided between the joint portion and the insulating pedestal portion. The prismatic secondary battery according to any one of claims 1 to 8, further comprising an engaging portion that engages and disengages.   The prismatic secondary battery according to any one of claims 1 to 9, wherein the joint portion includes a projection portion for welding and joining in a state where the bus bar is positioned.

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