JP6851870B2 - Secondary battery and manufacturing method of secondary battery - Google Patents

Description

The present invention relates to a secondary battery composed of a plurality of cell cells and a method for manufacturing the secondary battery.

Conventionally, nickel-metal hydride secondary batteries and the like have been used as in-vehicle power sources for electric vehicles and hybrid vehicles due to their high energy density. These secondary batteries are configured as an assembled battery, for example, by combining battery modules in which a plurality of single batteries are integrally housed in a resin square case so as to obtain a predetermined power capacity (for example,). , Patent Document 1).

In the battery module described in Patent Document 1, a plurality of rectangular parallelepiped electric tanks are connected to each other via a resin partition wall, and power generation elements are stored in the electric tanks so that adjacent power generation elements are electrically connected to each other. They are connected in series. The power generation element includes a positive electrode plate and a negative electrode plate, and the ends of these electrode plates are connected to the current collector plate. Then, by arranging the connecting protrusions of the current collector plate in the through holes provided in the partition wall of the electric tank, the connecting protrusions of the adjacent electric tanks are connected to each other through the through holes. Further, a sealing member for preventing the movement of the electrolytic solution between the electric tanks is arranged between the outer circumference of the connection protrusion and the outer circumference of the through hole at each connection protrusion.

JP-A-2007-123059

By the way, in the secondary battery, although it is necessary to prevent the movement of the electrolytic solution between the electric tanks, the two sealing members arranged at each connecting protrusion as in the technique described in Patent Document 1 use 1 Even if only one is used, it functions sufficiently to prevent movement to the extent that a short circuit does not occur between the cells adjacent to the battery case. However, in the technique described in Patent Document 1, if one of the sealing members is removed, the partition wall may be deformed by the pressing force of the remaining sealing member, and the sealing property may be deteriorated.

The present invention has been made in view of such circumstances, and an object of the present invention is a secondary battery capable of maintaining a sealing property against movement of an electrolytic solution between electric tanks, and a method for manufacturing the secondary battery. Is to provide.

The secondary battery for solving the above problems includes a partition wall for partitioning a plurality of electric tanks provided adjacent to each other in a resin case made of a thermoplastic resin, a group of electrode plates arranged in the electric tank, and the electrode. A secondary battery having a connection portion electrically connected to a plate group and a through hole provided in the partition wall for electrically connecting each of the connection portions in the adjacent battery case. The connecting portion is a sealing member that faces the partition wall around the protruding portion and the protruding portion inserted into the through hole, and can arrange an endless seal member that can be elastically deformed between the partition wall. The two connecting portions, which are provided with an arrangement portion and face each other with the partition wall in between, electrically connect the protruding portion of each of the connecting portions in the through hole, and the seal member of one of the connecting portions. The sealing member is arranged only in the arranging portion, and the partition wall includes a cured portion that is harder than the resin of the resin case in at least a part of the portion that the sealing member abuts.

According to such a configuration, even if only one seal member is provided around the through hole, the resin at the portion where the seal member comes into contact is unlikely to be deformed, so that the deformation due to the pressing force of the seal member is suppressed. .. In other words, since the seal member presses the hardened portion of the partition wall in one connection portion and the seal member arrangement portion becomes a space in the other connection portion, the deformation of the partition wall is suppressed even if there is a space on the opposite side. To. Therefore, the sealing property against the electrolytic solution between the electric tanks can be maintained.

Further, since the number of sealing members can be one, the number of parts can be reduced.
As a preferred configuration, the cured portion is wider than the range in which the sealing member comes into contact.
According to such a configuration, since the periphery of the sealing member is also cured, the deformation of the resin is further suppressed.

As a preferable configuration, the resin is a crystalline resin, and the crystallinity of the crystalline resin in the cured portion is higher than the crystallinity of the resin case.
According to such a configuration, a cured portion having an increased degree of crystallinity of the resin can be provided around the seal member. Since the crystallinity increases as the cooling rate of the molten resin becomes slower, the hardness of the cured portion can be adjusted.

As a preferred configuration, the hardness of the cured portion decreases as the seal member moves away from the contacted portion.
According to such a configuration, the hardness of the portion where the pressing force from the sealing member is strong, so-called rigidity and creep resistance, is enhanced, and the rigidity and the like decrease as the pressing force weakens away from the sealing member. The ratio of toughness will increase. This makes it possible to impart appropriate resistance around the through hole in the partition wall.

As a preferred configuration, the two connecting portions facing each other with the partition wall in between have the same protruding portion and the same shape of the sealing member arranging portion.
According to such a configuration, each protruding portion provided in the two connecting portions has the same shape, and each sealing member arranging portion has the same shape. Therefore, the connecting portion is formed, the protruding portion is welded, or the like. Easy electrical connection.

A method for manufacturing a secondary battery that solves the above problems is to electrically use a partition wall that is provided adjacent to each other in a resin case to partition a plurality of electric tanks and a group of plates arranged in the adjacent electric tanks. It is a method of manufacturing a secondary battery for manufacturing a secondary battery having a through hole provided in the partition wall so as to be connectable to the through hole, and the core portion inserted into the through hole and the penetration hole of the partition wall. A heating member including a pair of plate portions capable of sandwiching the periphery of the hole. The heating member is brought into contact with the partition wall by sandwiching the partition wall between the pair of plate portions while inserting the core portion through the through hole. A contact step of causing the heating member to be raised, a heating step of raising the temperature of the heating member to heat until the vicinity of the through hole is melted, and natural cooling of the raised temperature, or a longer cooling time than the natural cooling. It is provided with a cooling step for cooling the battery.

According to such a method, in a resin case having toughness that can withstand expansion, the partition wall integrally molded with the resin case is deformed by increasing the rigidity around the through hole while maintaining the toughness of the resin case. Can increase resistance to. Therefore, the sealing property against the electrolytic solution between the electric tanks can be maintained.

As a preferred method, in the contact step, the core portion is provided on one plate portion of the pair of plate portions, and when the partition wall is sandwiched between the pair of plate portions, the one plate portion is said to be said. The tip of the core portion is inserted into the through hole, and the tip of the core portion is brought into contact with the flat surface of the other plate portion not provided with the core portion.

According to such a method, the tip of the core portion of one plate portion through which the through hole is inserted is brought into contact with the flat surface of the other plate portion, so that the molten resin penetrates between the pair of plate portions. There is no risk of blocking the hole.

As a preferred method, in the cooling step, the heating amount is adjusted so that the temperature of the heating member is lowered.
According to such a method, the cooling time of the resin around the through hole can be made longer than the natural cooling by adjusting the heating amount of the heating member.

According to the present invention, it is possible to maintain the sealing property against the movement of the electrolytic solution between the electric tanks.

The schematic diagram which shows the schematic structure about one Embodiment which embodied a secondary battery. The cross-sectional view which shows the enlarged cross-sectional structure of the connection part in the same embodiment. The graph which shows the relationship between the crystallinity of a resin and time in the same embodiment. The flowchart which shows the processing procedure of the resin hardening process in the same embodiment. The figure which shows the state before the curing process of the resin in the same embodiment. The figure which shows the state during the curing process of the resin in the same embodiment. The figure which shows the state after the curing process of the resin in the same embodiment.

Hereinafter, a secondary battery according to the present invention and an embodiment embodying a method for manufacturing the secondary battery will be described with reference to FIGS. 1 to 7. Such a secondary battery is used, for example, as a power source for driving an automobile.

As shown in FIG. 1, the battery module is configured by electrically connecting a plurality of (for example, 6) cell cells 11 in series in order to obtain a required power capacity. The battery module has a structure in which a plurality of individual rectangular parallelepiped cell cells 11 are arranged. The cells 11 are arranged so that the short side surfaces corresponding to the side surface (long side surface) having the largest surface area of the electric tank 13 constituting the square accommodating portion are vertically viewed from each other.

As for the battery module, for example, a cell 11 made of a nickel-metal hydride secondary battery connects a plurality of short sides of the battery 13 constituting the battery module via a partition wall 12, and the battery module is formed into a square integrated battery 10 as a resin case. It is contained. Further, in the battery module, the upper surface opening of each battery case 13 is integrally sealed by the lid body 20. In each battery cell 13, as battery components, an electrode plate group 14 in which a positive electrode plate and a negative electrode plate are laminated via a separator, and current collector plates 15 and 16 as connecting portions joined to both sides thereof are provided. For example, it is housed together with an alkaline electrolyte.

The positive electrode plate and the negative electrode plate of the electrode plate group 14 are projected to the side portions opposite to each other to form lead portions 14a and 14b of the positive electrode plate and the negative electrode plate, and the side end edges of the lead portions 14a and 14b, respectively. The current collector plates 15 and 16 are joined. The current collector plates 15 and 16 are provided with connecting protrusions 15A and 16A as protrusions that project from the upper portions 15J and 16J toward the opposite sides of the lead portions 14a and 14b. The connecting protrusions 15A and 16A are formed in the upper part of the partition wall 12 and are inserted into through holes 17 used for connecting the electric tanks 13, and are electrically connected by spot welding through the through holes 17. .. As a result, the cell cells 11 having the adjacent electric tanks 13 are electrically connected in series.

Further, around the connecting protrusions 15A and 16A, ring accommodating portions 15B and 16B as seal member arranging portions are provided in an annular shape toward the lead portions 14a and 14b, respectively. Therefore, the ring accommodating portions 15B and 16B form concave annular spaces 15D and 16D facing the partition wall 12 on the opposite sides of the lead portions 14a and 14b, respectively. In the current collector plates 15 and 16 facing each other with the partition wall 12 interposed therebetween, a seal member is arranged in the annular space 15D of one of the current collector plates 15, and a seal member is arranged in the annular space 16D of the other current collector plate 16. Etc. are not placed. That is, in one of the annular spaces 15D, an O-ring 40 as a sealing member made of an elastic member such as rubber is arranged. The O-ring 40 arranged in one of the annular spaces 15D is pressed against the surface of the partition wall 12 around the through hole 17 by the surface of the ring accommodating portion 15B on the opposite side of the lead portion 14a, and the pressing pressure causes electricity. The movement of the electrolytic solution between the space in the tank 13 and the through hole 17 is blocked. The cutoff of the electrolytic solution here is a cutoff to the extent that movement can be prevented to the extent that a short circuit does not occur between the cells 11 of the adjacent electric tank 13.

Further, the negative electrode connection terminal 30 is attached to the through hole 19 located on the outer side of the electric tank 13 at the end, that is, the through hole 19 above the end side wall 10a of the integrated electric tank 10, which is on the left side in FIG. ing. The connection terminal 30 is connected to the electric tank 13 side by spot welding at the upper connection point 18 of the current collector plate 16 having an upper shape different from that of the connection protrusion 16A described above. Further, a positive electrode connection terminal 30 is attached to a through hole 19 located outside in the electric tank 13 at the right end (not shown), that is, a through hole above the end side wall 10a of the integrated electric tank 10. Then, the upper portion of the current collector plate 15 of the connection terminal 30 is connected to the electric tank 13 side by spot welding. By connecting the connection terminals 30 at both ends of the integrated battery 10 to the current collector plates 15 and 16, respectively, the total output of the battery 13, that is, the plurality of single batteries 11 connected in series is the connection terminals 30. Taken from.

With reference to FIG. 2, the configurations of the upper portions 15J and 16J of the current collector plates 15 and 16 will be described in detail.
The current collector plates 15 and 16 are provided with flat surface portions 15H and 16H that come into contact with the partition wall 12. In the upper portions 15J and 16J of the current collector plates 15 and 16, the connecting protrusions 15A and 16A are projected from the flat surfaces 15H and 16H toward the through hole 17 of the partition wall 12. In the current collector plates 15 and 16, the flat surface portion 15H is pressed against the surface of the partition wall 12 from the left side in the drawing, and the flat surface portion 16H is pressed against the surface of the partition wall 12 from the right side in the drawing. As a result, the connecting protrusions 15A and 16A of the current collector plates 15 and 16 are inserted into the through hole 17 to a depth of half that of the through hole 17, and come into contact with each other inside the through hole 17. Then, in the current collector plates 15 and 16, the contact between the flat surfaces 15H and 16H of the current collector plates 15 and 16 and the surface of the partition wall 12 is maintained by welding the two connecting protrusions 15A and 16A. ..

Further, the connecting protrusions 15A and 16A are formed so that the tip side thereof can be inserted into the through hole 17 and the base end side thereof has a size larger than the inner circumference of the through hole 17. In other words, the connecting protrusions 15A and 16A are reduced in diameter so that the outer diameter on the tip side that penetrates the through hole 17 fits into the inner diameter of the through hole 17. Therefore, the inner diameter side portion of the through hole 17 can be sandwiched between the tip end side and the base end side of the two connecting protrusions 15A and 16A. In the present embodiment, a step portion is formed between the tip end side and the base end side, and the outer peripheral portion of the through hole 17 can be sandwiched between the stepped portions.

However, as shown in FIG. 2, it may not be possible to sandwich the outer peripheral portion of the through hole 17 between the two connecting protrusions 15A and 16A due to processing tolerances, processing accuracy, and the like. For example, if the inner diameter of the through hole 17 is larger than the size that can be sandwiched between the two connection protrusions 15A and 16A, at least a part of the through hole 17 and, in the example of FIG. 2, the upper part of the hole is the two connection protrusions. It is not sandwiched between 15A and 16A. Further, for example, even if the through hole 17 is inclined with respect to the surface of the partition wall 12, at least a part of the through hole 17 is not sandwiched between the two connecting protrusions 15A and 16A.

The ring accommodating portions 15B and 16B form an annular space 15D and 16D around the through hole 17. The ring accommodating portions 15B and 16B are connected to the connecting protrusions 15A and 16A in which the inner peripheral side of the ring is inserted into the through hole 17, and the outer peripheral side is connected to the flat surfaces 15H and 16H of the current collector plates 15 and 16. Therefore, at least a part of the ring accommodating portions 15B and 16B on the inner peripheral side abuts on the surface of the partition wall 12 through the through hole 17, and at least a part on the outer peripheral side abuts on the surface of the partition wall 12 by the flat surfaces 15H and 16H. As a result, the above-mentioned annular spaces 15D and 16D are formed between the partition wall 12 and the surface thereof.

As shown in FIG. 2, in the present embodiment, the O-ring 40 is arranged in the annular space 15D on the left side in the figure, and the annular space 16D on the right side in the figure remains a space.
The O-ring 40 is an annular and endless sealing member made of a known rubber material or the like. The thickness of the O-ring 40 is formed to be thicker than the depth of the ring accommodating portion 15B. Therefore, the O-ring 40 arranged in the ring accommodating portion 15B projects toward the surface of the partition wall 12 from the flat surface portion 15H of each current collector plate 15. Therefore, when the current collector plate 15 comes into contact with the surface of the partition wall 12, the O-ring 40 is elastically deformed by being sandwiched between the inner surface of the ring accommodating portion 15B and the surface of the partition wall 12. The elastically deformed O-ring 40 applies a reaction force, a so-called elastic force, between the inner surface of the ring accommodating portion 15B and the surface of the partition wall 12, and provides a necessary seal between the current collector plate 15 and the partition wall 12. Ensure sex. As a result, the O-ring 40 prevents the movement of the electrolytic solution into the through hole 17 of the partition wall 12 to the extent that a short circuit does not occur between the cells 11 adjacent to the battery case 13. Since the battery module does not cause a short circuit due to the movement of the electrolytic solution, a communication hole that allows gas movement between the electric tanks 13 may be provided above the through hole 17 in which the electrolytic solution is not arranged.

On the other hand, in the partition wall 12 with which the O-ring 40 of the annular space 15D abuts, a space is secured on the annular space 16D side. Therefore, while the reaction force from the O-ring 40 to the right in the figure continues to be applied to the partition wall 12, the force from the annular space 16D to the left in the figure is not applied to the partition wall 12. That is, the periphery of the through hole 17 of the partition wall 12 is unilaterally pushed in the direction of the annular space 16D. At this time, in FIG. 2, the lower side 17b of the through hole 17 engages with the tip end side and the base end side of the connection protrusion 16A. Therefore, the partition wall 12 is supported by the connecting protrusion 16A, which is two points sandwiching the annular space 16D, and the flat surface portion 16H of the current collector plate 16, so-called two-point support, and the pressing force from the O-ring 40 is also two-point support. You will be able to accept it. However, in FIG. 2, the upper side 17a of the through hole 17 does not engage with the tip end side and the base end side of the connection protrusion 16A. That is, the partition wall 12 is not supported by the connecting protrusion 16A, but is supported only by the flat surface portion 16H of the current collector plate 16, which is a so-called cantilever support. Therefore, the partition wall 12 may be deformed by the upper side 17a of the through hole 17 being pushed and bent in the direction of the annular space 16D by the pressing force from the O-ring 40.

The partition wall 12 is integrally molded as an integrated electric tank 10. The integrated battery case 10 is made of a crystalline resin as a thermoplastic resin, and is formed by injection molding. Examples of the crystalline resin include high-density polyethylene (HDPE) -based resin, low-density polyethylene (LDPE) -based resin, and polypropylene (PP) -based resin.

Since the long side surface of the integrated battery tank 10 needs to have flexibility, so-called toughness, that can cope with expansion caused by an increase in internal pressure due to a charge / discharge reaction of a secondary battery or the like, injection molding is performed so as to ensure toughness. After that, it is solidified by rapid cooling.

Graph L1 of FIG. 3 shows the relationship between the cooling time (time until solidification) and the crystallinity. More specifically, the shorter the cooling time, the lower the crystallinity of the crystalline resin, and the longer the cooling time, the higher the crystallinity. Further, when the crystallinity is low, the toughness is high, but the rigidity and creep resistance are low, and conversely, when the crystallinity is high, the toughness is low, but the rigidity and creep resistance are high.

Therefore, the integrated battery case 10 is rapidly cooled after injection molding so that the toughness is maintained high, in other words, the rigidity and the like are maintained low, and for example, the crystallinity of the crystalline resin is low. It is maintained at P1 (FIG. 3). That is, even if the partition wall 12 is formed at the same time as the integrated electric tank 10, it has the same high toughness and low rigidity as the resin case. By the way, since the toughness is flexible to deformation, there is a possibility that the toughness will be deformed so as to bend according to the pressing force continuously applied from the O-ring 40 or the like. As described above, since the reaction force is continuously applied from the O-ring 40 around the through hole 17, the upper side 17a of the through hole 17 which is cantilevered is the O-ring 40. May bend in the opposite direction. The O-ring 40 secures the sealing property between the ring accommodating portion 15B and the surface of the partition wall 12 by the surface pressure of the portion in contact with the ring accommodating portion 15B and the surface of the partition wall 12. Since the surface pressure is maintained high in response to the large elastic deformation of the O-ring 40, when the surface of the partition wall 12 is pressed by the O-ring 40 and deformed, the elastic deformation of the O-ring 40 becomes small. As a result, the surface pressure may decrease and the sealing performance may also decrease.

Therefore, in this embodiment, a hardened portion 21 is provided around the through hole 17. Since the hardened portion 21 has higher rigidity around the through hole 17 of the partition wall 12 and lower toughness than when the integrated electric tank 10 is formed, it cantilevered like the upper side 17a of the through hole 17. Even in the support portion, deterioration of the sealing property can be suppressed. That is, as described above, the integrated electric tank 10 is formed to have toughness and flexibility on both the long side surface and the partition wall 12, but the hardened portion is formed around the through hole 17 of the partition wall 12. 21 was formed. On the contrary, since the long side surface of the integrated electric tank 10 is not hardened, the toughness and flexibility imparted at the time of molding are maintained on the long side surface. As a result, the long side surface of the integrated battery 10 can cope with deformation such as expansion due to an increase in internal pressure due to a charge / discharge reaction of the secondary battery or the like.

As shown in FIG. 2, the cured portion 21 is provided around the through hole 17 of the partition wall 12 as a circular range with the center of the through hole 17 as the center P0. The circular range is provided as a proximity range 22 having a radius of the end portion P2a which is the upper end portion of the current collector plate 16 on the upper side 17a of the through hole 17. The distance from the center P0 of the corresponding position P2b on the lower side 17b of the through hole 17 is the same as the distance from the center P0 of the end portion P2a. Since the portion of the partition wall 12 that abuts on the outer peripheral portion P1a of the annular space 16D, which is the fulcrum of the cantilever support portion, is curved by the pressing force from the O-ring 40, the range including the outer peripheral portion P1a is cured. Curvature is suppressed.

That is, the partition wall 12 is also suppressed from being curved by hardening at least the portion of the cantilever support portion that abuts on the outer peripheral portion P1a that is the fulcrum of the curvature. Therefore, the radius of the circular range can be at least the position on the upper side 17a of the through hole 17 past the outer peripheral portion P1a of the annular space 16D. Here, if the cured portion 21 has a length of 0.2 mm or more in the direction opposite to the center P0 from the outer peripheral portion P1a, the bending of the partition wall 12 due to the pressing force from the O-ring 40 is preferably suppressed. Normally, since the distance between the outer peripheral portion P1a and the end portion P2a is 0.2 mm or more, if the partition wall 12 is cured from the center P0 side to the end portion P2a, the curvature of the partition wall 12 is preferably suppressed. The distance from the center P0 of the outer peripheral portion P1b of the annular space 16D on the lower side 17b of the through hole 17 is the same as the distance from the center P0 of the outer peripheral portion P1a.

That is, in the vicinity range 22 close to the through hole 17, the hardened portion 21 having higher rigidity and lower toughness than the integrated electric tank 10 is provided in the range including the outer peripheral portions P1a and P1b of the annular space 16D. As a result, deformation of the partition wall 12 due to the pressing force of the O-ring 40 is suppressed, and deterioration of the sealing property is suppressed even if a cantilever support portion of the partition wall 12 is generated around the through hole 17. Will be done.

A method for manufacturing a secondary battery having a cured portion 21 on the partition wall 12 will be described with reference to FIGS. 4 to 7.
First, an outline of a method for manufacturing a secondary battery will be described with reference to FIG. Here, among the processes for manufacturing the secondary battery, a process in which the electrode plate group 14 is arranged in the integrated battery tank 10 will be described in particular. In the secondary battery manufacturing process, various processes are controlled by the secondary battery manufacturing apparatus 100 (see FIG. 5). The secondary battery manufacturing device 100 includes an arithmetic unit such as a computer, a heating member 50, a driving device for moving the heating member 50, a heating device for raising the temperature of the heating member 50, and the like.

As shown in FIG. 4, when the method for manufacturing the secondary battery is started, the battery transport process in which the integrated battery module 10 of the injection-molded battery module is transported to the processing position is performed (step S10). The electric tank transport process is performed by a transport device (not shown).

Next, the secondary battery manufacturing apparatus 100 moves the heating member 50 toward the through hole 17 of the partition wall 12 and performs a hot plate contact process which is a process of contacting the through hole 17 of the partition wall 12 and its periphery. (Contact step: step S11). Subsequently, the secondary battery manufacturing apparatus 100 performs a heat treatment for heating the heating member 50 (heating step: step S12), and when the heat treatment is completed, performs a hot plate cooling treatment for cooling the heating member (cooling). Step: Step S13). Then, the secondary battery manufacturing apparatus 100 performs a hot plate removing process of separating the heating member 50 from the partition wall 12 (step S14).

After that, the secondary battery manufacturing apparatus 100 performs the electrode plate group insertion process (step S15), and the current collector plates 15 and 16 of the electrode plate group 14 arranged in the adjacent electric tank 13 are spot-welded to each other. Welding between the electrode plates to be connected is performed (step S16). Then, the arrangement of the electrode plate group 14 in the integrated electric tank 10 is completed.

Subsequently, the process between the hot plate contact process (step S11) and the hot plate removal process (step S14) will be described in detail with reference to FIGS. 5 to 7.
As shown in FIG. 5, the heating member 50 includes a core portion 52 inserted into the through hole 17 of the partition wall 12 and a pair of plate portions 51 and 53 capable of sandwiching the periphery of the through hole 17 of the partition wall 12. Since the hardened portion 21 is provided around the through hole 17 of the partition wall 12 as a circular range centered on the center P0 of the through hole 17, the pair of plate portions 51 and 53 is circular with the core portion 52 as the center. be able to. Further, since the plate portions 51 and 53 are circular, the possibility of being curved or distorted due to heating of the plate portions 51 and 53 or sandwiching between the two plate portions 51 and 53 is suppressed. Further, if the two plate portions 51 and 53 are circular, the partition wall 12 can be heated more evenly. Further, if the two plate portions 51 and 53 are circular, it is easy to manufacture the two plate portions 51 and 53.

Then, as shown in FIG. 6, when the hot plate contact treatment (step S11) is started, the plate portion 51 of the heating member 50 is arranged at a position where the core portion 52 can be inserted into the through hole 17 of the partition wall 12. At the same time, the plate portion 53 is arranged at a position facing the plate portion 51 with the partition wall 12 interposed therebetween. Then, the heating member 50 narrows the distance between the pair of plate portions 51 and 53 so that the core portion 52 is inserted through the through hole 17 of the partition wall 12 and the partition wall 12 is sandwiched between the pair of plate portions 51 and 53. To do. At this time, the tip of the core portion 52 of one plate portion 51 through which the through hole 17 is inserted comes into contact with the flat surface of the other plate portion 53. That is, the core portion 52 contacts the inner circumference of the through hole 17, and the pair of plate portions 51, 53 contact both surfaces of the partition wall 12, so that the heating member 50 contacts the partition wall 12.

Following the contact of the heating member 50 with the partition wall 12, the heat treatment (step S12) is started. In the heat treatment, the temperature of the heating member 50 is raised to melt the periphery of the through hole 17. The temperature of the heating member 50 is raised by well-known techniques such as electric heater, electromagnetic wave irradiation, and laser irradiation. The heating member 50 is a partition wall so as to melt the resin inside the pair of plate portions 51 and 53 and in the vicinity of the core portion 52, while not melting the resin in the vicinity of the outer periphery of the pair of plate portions 51 and 53. 12 is heated. For example, in the heating member 50, it is preferable that the outer peripheral portion side of the pair of plate portions 51, 53 has a lower temperature than the central portion. By not melting the partition wall 12 corresponding to the outer peripheral portions of the pair of plate portions 51 and 53, resin outflow and deformation of the partition wall 12 are suppressed. The heating member 50 is provided with temperature sensors at one or a plurality of locations in the central portion and the outer peripheral portion of the plate portions 51 and 53 to monitor the temperature so that the central portion is melted and the outer peripheral portion is not melted. Can be heated to. Further, in the heating member 50, the time for which the central portion of the partition wall 12 to be heated is melted and the outer peripheral portion is not melted is set in advance by experiment or theory, and the partition wall 12 is heated only for this set time. Good.

Following heating until the resin of the partition wall 12 is melted, the hot plate cooling process (step S13) is started. In the hot plate cooling treatment, the molten resin is cooled so that the crystallinity of the crystalline resin is increased. At this time, it is preferable to cool at least a cooling time longer than the cooling time when the integrated electric tank 10 is molded. The cooling here may be natural cooling, or may be cooled so that the cooling time is longer than that of natural cooling. As shown in the graph L1 of FIG. 3, the crystallinity of the resin increases according to the length of time required for the molten resin to solidify. Therefore, the cooling time is set so that the crystallinity corresponding to the required rigidity and the like is obtained around the through hole 17 of the partition wall 12. For example, since the heating member 50 has a heat capacity, a long cooling time may be secured by naturally cooling the partition wall 12 while sandwiching the partition wall 12 between the pair of plate portions 51 and 53. Further, by reducing the calorific value of the heating member 50, the heating amount for the partition wall 12 may be reduced to secure a longer cooling time than the natural cooling.

As shown in FIG. 7, following that the resin of the partition wall 12 has been cooled, the hot plate removing process (step S14) is started. That is, in the heating member 50, the surface of the partition wall 12 and the partition wall 12 are formed by widening the distance between the core portion 52 and the pair of plate portions 51, 53 that were in contact with the partition wall 12 and the pair of plate portions 51, 53. It is separated from the through hole 17 of. This completes the hot plate removal process.

Here, the crystallinity of the hardened partition wall 12 will be described with reference to FIG. 7. For convenience of explanation, the case where the crystallinity differs in three stages will be described below, but the crystallinity may differ in four or more stages depending on the time required for solidification, or stepless. May differ from.

First, since the heating member 50 also has a core portion 52 at the center, the heating capacity is large and it takes time to cool. On the other hand, the peripheral portions of the pair of plate portions 51 and 53 have a small heat capacity, and the outer periphery has a large area, so that the heat dissipation rate is high and the time required for cooling is short. Further, since the vicinity of the outer circumferences of the plate portions 51 and 53 does not melt, the crystallinity of the resin when the integrated electric tank 10 is injection-molded is maintained.

Therefore, the crystallinity of the resin around the through hole 17 of the partition wall 12 thus heat-treated decreases as the distance from the vicinity of the through hole 17 increases. In other words, it becomes lower as the seal member in the vicinity of the through hole 17 moves away from the abutting portion. For example, the proximity range 22 including the annular range with the through hole 17 as the inner circumference has a high degree of crystallinity because the cooling time is long. That is, it becomes the cured portion 21 in the integrated electric tank 10. Further, the intermediate range 23 consisting of the range from the outer circumference of the vicinity range 22 to the outer periphery of the pair of plate portions 51 and 53 easily dissipates heat, so that the cooling time is shorter than the cooling time of the vicinity range 22 and crystals are formed. The degree of crystallinity is lower than the neighborhood range 22, but higher than the rest of the unheated partition wall 12. That is, it becomes the cured portion 21 in the integrated electric tank 10. Then, in the case of such a cured portion 21, deformation due to pressing force from the O-ring 40 is suppressed.

As described above, according to the secondary battery of the present embodiment and the method for manufacturing the secondary battery, the effects described below can be obtained.
(1) Even if one O-ring 40 is provided around the through hole 17, the resin at the portion where the O-ring 40 abuts is difficult to be deformed, so that the deformation caused by the pressing force of the O-ring 40 is suppressed. Will be done. In other words, in the upper portion 15J of one current collector plate 15, the O-ring 40 presses the hardened portion 21 of the partition wall 12, and in the upper portion 16J of the other current collector plate 16, the ring accommodating portion 16B becomes a space, but O- Even if there is a space on the opposite side of the ring 40 across the partition wall 12, the deformation of the partition wall 12 is suppressed. Therefore, the sealing property against the electrolytic solution between the electric tanks 13 can be maintained.

Further, since the O-ring 40 can be made into one, the number of parts is reduced.
(2) Since the periphery of the O-ring 40 is also cured, the deformation of the resin is further suppressed.

(3) A cured portion 21 having an increased degree of crystallinity of the resin can be provided around the O-ring 40. Since the crystallinity increases as the cooling rate of the molten resin becomes slower, the hardness of the cured portion 21 can be adjusted.

(4) The hardness of the part where the pressing force from the O-ring 40 is strong, so-called rigidity and creep resistance, is increased, and the rigidity and the like decrease as the pressing force weakens away from the O-ring 40. The proportion of toughness will increase. This makes it possible to impart appropriate resistance to the periphery of the through hole 17 in the partition wall 12.

(5) The connecting protrusions 15A and 16A provided on the upper portions 15J and 16J of the two current collector plates 15 and 16 have the same shape, and the ring accommodating portions 15B and 16B have the same shape. Electrical connection is facilitated by forming the upper portions 15J and 16J of the electric plates 15 and 16 and welding the connecting protrusions 15A and 16A.

(6) In the integrated electric tank 10 having toughness that can withstand expansion, while maintaining the toughness of the integrated electric tank 10, the partition wall 12 integrally molded with the integrated electric tank 10 has the rigidity around the through hole 17. It can be increased to increase resistance to deformation. Therefore, the sealing property against the electrolytic solution between the electric tanks 13 can be maintained.

(7) A resin melted between a pair of plate portions 51 and 53 by abutting the tip of the core portion 52 of one plate portion 51 through which the through hole 17 is inserted in contact with the flat surface of the other plate portion 53. Does not block the through hole 17.

(8) By adjusting the heating amount of the heating member 50, the cooling time of the resin around the through hole 17 can be made longer than that of natural cooling.
(Other embodiments)
The above embodiment can also be implemented in the following embodiments.

-In the above embodiment, the battery module is composed of six cell cells 11, but it may be composed of a plurality of cell cells other than six.
-In the above embodiment, the case where the connection protrusions 15A and 16A are electrically connected by spot welding has been illustrated. However, not limited to this, if two connecting protrusions facing each other are electrically connected, even if they are electrically connected by a welding technique other than spot welding such as arc welding, laser beam welding, and electron beam welding. Good.

-In the above embodiment, the case where there is a through hole 17 in the portion to be heat-treated has been illustrated. However, the present invention is not limited to this, and if the through hole is formed after the heat treatment, the through hole may not be present at the time of the heat treatment, and at this time, the core portion is not required as the heating member.

-In the above embodiment, the case where the resin is melted has been illustrated. However, the present invention is not limited to this, and the resin does not have to be melted as long as the cured portion 21 can be formed by heating within a range in which the shape is maintained. Further, in this case, the core portion may or may not be present.

-In the above embodiment, the case where the upper portions 15J and 16J of the current collector plates 15 and 16 have the same shape is illustrated. However, the present invention is not limited to this, and the shapes of the upper portions facing each other across the partition wall may be different. For example, one may be provided with a ring accommodating portion and the other may not be provided with a ring accommodating portion. For example, the length of the upper portion of the other portion may be shorter than that of the ring accommodating portion of one.

-In the above embodiment, the pair of plate portions 51 and 53 is formed into a circle centered on the core portion 52. However, the present invention is not limited to this, and the pair of plate portions may have a triangular shape, a rectangular shape, another polygonal shape, an ellipse, or the like. For example, since the partition wall 12 has a vertically long shape, as a pair of plate portions, when the length of the cured portion along the long side of the partition wall 12 in the vertical direction is longer than the width of the short side of the partition wall 12, it is not circular. It becomes a shape such as an ellipse.

Further, the plane may be eccentric or asymmetric with respect to the core portion.
Further, the shapes of the two plate portions constituting the pair of plate portions may be different.
The cured portion 21 can include up to the upper end position P3a of the partition wall 12 in the direction of the upper side 17a of the through hole 17.

At this time, for example, the distance from the outer peripheral portion P1a to the upper end position P3a can be about 20 times the distance from the outer peripheral portion P1a to the end portion P2a. Therefore, the distance from the outer peripheral portion P1a to the end portion P2a can be set to 0.3 mm, and the distance from the outer peripheral portion P1a to the upper end position P3a can be set to 6 mm. At this time, if the upper side and the lower side have the same length, the length of the hot plate in the vertical direction can be made uniform with respect to the center P0, which is preferable.

Further, in the direction of the lower side 17b of the through hole 17, the maximum end position P3b of the partition wall 12 can be included.
-In the above embodiment, the case where the cured portion 21 is in a circular range is illustrated. However, the present invention is not limited to this, and the cured portion may be in a range other than the circular shape. The shape of the cured portion may be a triangle, a rectangle, another polygonal shape, an ellipse, or the like, as long as the cured portion can be made wider than the neighborhood range 22.

-In the above embodiment, the case where the cured portion 21 is in a circular range is illustrated. However, the present invention is not limited to this, and the cured portion may be a portion where the partition wall is supported at two points or a small portion, while the portion where the partition wall is cantilevered is supported up to a portion which abuts on the outer circumference of the annular space. For example, the cured portion may not surround the through hole but may be a part around the through hole.

In the above embodiment, the case where the cured portion 21 is provided around the through hole 17 of the partition wall 12 up to the outer peripheral portions P1a and P1b of the annular space 16D or a wider portion thereof is illustrated. However, the present invention is not limited to this, and if the cured portion 21 is around the through hole 17 of the partition wall 12, it may be located only in the outer peripheral portions P1a and P1b of the annular space 16D. For example, even if a cured portion is provided in a portion inside the outer peripheral portions P1a and P1b of the annular space 16D, the deformation of the partition wall is suppressed by the cured portion.

-In the above embodiment, the case where the secondary battery is a nickel hydrogen secondary battery has been illustrated, but the present invention is not limited to this, and the secondary battery may be a secondary battery that uses an electrolytic solution, and such a secondary battery may be used. Examples thereof include a nickel cadmium secondary battery.

-In the above embodiment, the case where the secondary battery is used as a power source for an automobile has been illustrated. However, the present invention is not limited to this, and the secondary battery may be used as a power source other than the automobile such as various moving bodies and fixed bodies as long as it is used as a power source.

10 ... Integrated battery tank, 10a ... End side wall, 11 ... Cellular cell, 12 ... Partition wall, 13 ... Battery tank, 14 ... Plate group, 14a, 14b ... Lead part, 15 ... Current collector plate, 15A ... Connection protrusion, 15B ... ring accommodating part, 15D ... annular space, 15H ... flat part, 15J ... upper part, 16 ... current collector plate, 16A ... connecting protrusion, 16B ... ring accommodating part, 16D ... annular space, 16H ... flat part, 16J ... Upper part, 17 ... through hole, 18 ... connection point, 19 ... through hole, 20 ... lid, 21 ... hardened part, 22 ... neighborhood range, 23 ... intermediate range, 30 ... connection terminal, 50 ... heating member, 51 ... plate Part, 52 ... Core part, 53 ... Plate part, 100 ... Manufacturing equipment.

Claims (5)

A partition wall for partitioning a plurality of electric tanks provided adjacent to each other in a resin case made of a thermoplastic resin, a group of plates arranged in the electric tank, and a connection portion electrically connected to the group of electric plates. A secondary battery provided with a through hole provided in the partition wall for electrically connecting each of the connecting portions in the adjacent battery case.
The connection portion is a seal member that faces the partition wall around the protrusion and the protrusion inserted into the through hole, and can arrange an elastically deformable endless seal member between the partition wall. Equipped with an arrangement part,
The two connecting portions facing each other across the partition wall electrically connect the protruding portion of each of the connecting portions in the through hole, and seal only to the sealing member arranging portion of one of the connecting portions. Members are placed,
The partition wall is a secondary battery having a cured portion that is harder than the resin of the resin case at least a part of the portion that the seal member comes into contact with. The secondary battery according to claim 1, wherein the cured portion is wider than a range in which the seal member abuts. The resin is a crystalline resin and
The secondary battery according to claim 1 or 2, wherein the cured portion has a crystallinity of the crystalline resin higher than that of the resin case. The secondary battery according to any one of claims 1 to 3, wherein the hardness of the cured portion becomes lower as the sealing member moves away from the contacting portion. The second item according to any one of claims 1 to 4, wherein each of the two connecting portions facing each other with the partition wall in between has the same shape as the protruding portion and the same shape as each of the sealing member arranging portions. Next battery .

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