Method for manufacturing an electricity storage device

Abstract

To provide a method for producing a power storage device, in which a resin member fixing a terminal member to a case member contains no air bubbles therein and also the case member has not been deformed.SOLUTION: A method for producing a power storage device 1 includes an insert-molding step S1 of making a resin member 60 (70) by insert-molding while a terminal member 40 (50) is inserted in an insertion hole 22a (22b) of a case member 22. In this insert-molding step S1, the insertion hole 22a (22b) of the case member 22 is placed in front F of a gate GT, and a molten resin MR is injected through the gate GT to flow in an opposite gate-side space CV2 in a cavity CV through the insertion hole 22a (22b), allowing the molten resin MR to spread over the entire cavity CV, to form the resin member 60 (70).SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to a method for manufacturing an electricity storage device such as a battery or a capacitor in which a terminal member is fixed via a resin member to a case member that forms part of the case. [Background technology]

[0002] As an electric storage device, a rectangular battery is known in which positive and negative terminal members are fixed to a rectangular box-shaped case via an insert-molded resin member. Specifically, the case is composed of a base-closed rectangular cylindrical body member having a rectangular annular opening, and a rectangular plate-shaped cover member joined to the body member over its entire circumference in a manner that closes the opening. The positive and negative terminal members are inserted into a pair of insertion holes provided in the cover member, respectively, and extend from the inside to the outside of the case. The pair of resin members are joined to the cover member and the terminal members, respectively, while insulating the cover member from the terminal members, and fix the terminal members to the cover member.

[0003] Such a battery is assembled by the following method. That is, with positive and negative terminal members inserted into a pair of insertion holes in a lid member, a pair of resin members are insert-molded to integrate the terminal members with the lid member via the resin members. Next, the positive and negative terminal members of this lid assembly are connected to the positive and negative current collectors of the electrode body, respectively. Thereafter, this electrode body is inserted into a main body member, the opening of the main body member is closed with a lid member, and the entire circumference is laser-welded to form a case. For example, Patent Documents 1 and 2 are examples of related prior art (see, for example, Figures 1 and 2, paragraph (0018) of Patent Document 1, and Figures 1 to 3, paragraph (0080) of Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2010-272324 A [Patent Document 2] JP 2018-097978 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, during the above-mentioned insert molding, if a cover member (case member) is present in front of the gate, the molten resin injected from the gate hits the cover member (case member), and the molten resin cannot be smoothly distributed throughout the cavity. Therefore, if the resin pressure of the molten resin is low, air bubbles may form inside the completed resin part. On the other hand, if the resin pressure is increased to suppress the generation of air bubbles, deformation may occur in the part of the cover member (case member) that comes into contact with the molten resin.

[0006] The present invention has been made in consideration of the current situation, and provides a method for manufacturing an electricity storage device, which can manufacture an electricity storage device that has no air bubbles inside the resin member that insulates and fixes the terminal member to the case member, and that does not cause deformation of the case member. [Means for solving the problem]

[0007] (1) One aspect of the present invention for solving the above problem is a manufacturing method for an electricity storage device including a case member having an insertion hole, a terminal member inserted into the insertion hole of the case member, and a resin member that is joined to the case member and the terminal member while insulating the case member from the terminal member, and fixes the terminal member to the case member, the insertion hole has an insertion portion through which the terminal member is inserted and a notch portion extending from the insertion portion, The insert molding step includes insert molding the resin member with the terminal member inserted into the insertion hole of the case member, and the insert molding step includes inserting the resin member into the insertion hole of the case member in front of a gate for injecting molten resin into a cavity formed by the case member, the terminal member, and a molding die. The above-mentioned cutout portion and the molten resin injected from the gate is poured through the insertion hole into a space on the anti-gate side of the cavity on the opposite side from the gate relative to the case member, and allowed to permeate the entire cavity to form the resin member. This is a manufacturing method for an electricity storage device.

[0008] In the above-mentioned method for manufacturing an electric storage device, in the insert molding process, the insertion hole of the case member is positioned in front of the gate, and the molten resin injected from the gate is poured into the space on the opposite side of the cavity through the insertion hole and spread throughout the entire cavity, so that the molten resin can be smoothly spread throughout the entire cavity. Therefore, even if the resin pressure of the molten resin is reduced, a resin member without air bubbles inside can be molded. Meanwhile, since the resin pressure can be reduced, deformation of the case member can be prevented. Thus, an electric storage device without air bubbles inside the resin member and without deformation of the case member can be manufactured. In addition, in designing an electricity storage device, it may be desirable to make the resin member as small as possible, and therefore the insertion hole may also be desired to be as small as possible. Since the above-mentioned insertion hole has an insertion portion through which the terminal member is inserted and a notch portion extending from the insertion portion, it is possible to make the insertion hole smaller and the resin member smaller than when the overall shape of the insertion hole is rectangular or elliptical. And, even though the insertion hole and the resin member are small, it is possible to manufacture an electricity storage device in which there are no air bubbles inside the resin member and the case member is not deformed.

[0011] ( 2 )Furthermore(1 ) The method for manufacturing the described electric storage device may be such that the terminal member is located outside the case member and has a flat terminal outer flat portion including an exposed, planar terminal top surface, and the resin member is located outside the case member and has a frame-shaped resin outer frame portion that surrounds the terminal outer flat portion of the terminal member and is flush with the terminal top surface of the terminal outer flat portion.

[0012] When an energy storage device includes a terminal member having the above-mentioned terminal top surface and a resin member having a resin outer frame portion, during insert molding, part of the molten resin supplied around the terminal outer flat portion to form the resin outer frame portion may further flow into between the terminal top surface of the terminal outer flat portion and the molding die, making it easy for resin burrs to form on the terminal top surface after insert molding. However, in the above-mentioned manufacturing method, since the resin pressure can be reduced as described above, it is possible to prevent a portion of the molten resin supplied around the outer flat portion of the terminal from flowing further into the gap between the top surface of the terminal of the outer flat portion of the terminal and the molding die. Furthermore, the molten resin that flows into the space on the opposite side of the cavity flows around the back surface of the terminal of the outer flat portion of the terminal and presses the outer flat portion of the terminal against the molding die from the back surface side of the terminal, so that the top surface of the terminal is in close contact with the molding die. This effectively prevents the molten resin from flowing into the gap between the molding die and the top surface of the terminal. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a perspective view of a battery according to an embodiment. [Diagram 2] 1 is a cross-sectional view of a battery according to an embodiment taken along a battery height direction and a battery width direction. [Diagram 3] FIG. 2 is a partially enlarged top view of the vicinity of a terminal member and a resin member in the battery according to the embodiment. [Figure 4] 6 is a cross-sectional view taken along the line AA in FIGS. 3 and 5, showing the vicinity of a terminal member and a resin member in the battery according to the embodiment. FIG. [Diagram 5] 5 is a cross-sectional view taken along the arrow BB in FIGS. 3 and 4, showing the vicinity of a terminal member and a resin member in the battery according to the embodiment. FIG. [Figure 6] 2 is a flowchart of a method for manufacturing a battery according to an embodiment. [Figure 7] 4 is an explanatory diagram showing a state in which molten resin is injected from a gate into a cavity in an insert molding process in a manufacturing method for a battery according to an embodiment. FIG. [Figure 8] 11 is an explanatory diagram showing a state in which a resin member is molded in a cavity in an insert molding step in a manufacturing method of a battery according to an embodiment. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 shows a perspective view of a battery (electricity storage device) 1 according to this embodiment, and Fig. 2 shows a cross-sectional view of the battery 1. Fig. 3 shows a partially enlarged top view of the vicinity of a terminal member 50 and a resin member 60, and Figs. 4 and 5 show partially enlarged cross-sectional views of the vicinity of the terminal member 50 and the resin member 60. In the following description, the battery height direction AH, the battery width direction BH, and the battery thickness direction CH of the battery 1 are defined as the directions shown in Figs. 1 to 5. The battery 1 is a rectangular (rectangular) sealed lithium ion secondary battery that is mounted on vehicles such as hybrid cars, plug-in hybrid cars, and electric cars.

[0015] The battery 1 is composed of a case 10, a flat wound electrode assembly 30 housed in the case 10, a positive electrode terminal member 40 and a negative electrode terminal member 50 each supported on a case top 11 (lid member 22) of the case 10, etc. The electrode assembly 30 is covered in the case 10 by a bag-shaped insulating holder 5 made of an insulating film and opening to the upper side AH1 in the battery height direction AH. An electrolyte 3 is also housed in the case 10, a part of which is impregnated in the electrode assembly 30, and the remainder is pooled on the case bottom 12 of the case 10.

[0016] Of these, the case 10 is a rectangular parallelepiped box made of metal (aluminum in this embodiment) and has a rectangular case upper part 11 located on the upper side AH1 in the battery height direction AH, a rectangular case bottom part 12 facing the upper part 11 and located on the lower side AH2 in the battery height direction AH, and four rectangular case side parts 13, 14, 15, and 16 connecting the upper part 11 and the lower side AH2. The case 10 is composed of a bottomed square cylindrical main body member 21 having a rectangular annular opening 21c on the upper side AH1, and a rectangular plate-like cover member (case member) 22 laser-welded to the main body member 21 over the entire periphery in a form that closes the opening 21c.

[0017] The case upper portion 11 (lid member 22) is provided with a safety valve 28 that breaks and opens when the internal pressure of the case 10 exceeds the valve opening pressure. The lid member 22 is also provided with a liquid injection hole 22k that communicates between the inside and outside of the case 10, and is airtightly sealed with a disk-shaped sealing member 29 made of aluminum. Furthermore, the lid member 22 is provided with insertion holes 22a, 22b near the ends of one side BH1 and the other side BH2 in the battery width direction BH. Each insertion hole 22a, 22b is composed of a rectangular insertion portion 22a1, 22b1 and a notch portion 22a2, 22b2 extending from the insertion portion 22a1, 22b1. Specifically, the notch portion 22a2 extends from the center of the insertion portion 22a1 in the battery thickness direction CH toward the other side BH2 in the battery width direction BH, and the notch portion 22b2 of the other negative electrode extends from the center of the insertion portion 22b1 in the battery thickness direction CH toward the one side BH1 in the battery width direction BH. A positive electrode terminal member 40 made of aluminum is inserted into an insertion portion 22a1 of one of the insertion holes 22a and is fixed to the lid member 22 in a state insulated from the case 10 via a resin member 60. A negative electrode terminal member 50 made of copper is inserted into an insertion portion 22b1 of the other insertion hole 22b and is fixed to the lid member 22 in a state insulated from the case 10 via a resin member 70.

[0018] These terminal members 40, 50 are each formed by punching out a metal plate (the positive terminal member 40 is an aluminum plate, and the negative terminal member 50 is a copper plate) into a predetermined shape and bending it, and have a terminal outer flat plate portion 41, 51 located on the outer side EH of the cover member 22, and a terminal inner portion 42, 52 located mainly inside the case 10 and connected to the terminal outer flat plate portion 41, 51 via the insertion holes 22a, 22b. The terminal outer flat plate portion 41, 51 has a rectangular flat plate shape and has a rectangular flat terminal top surface 41m, 51m. There is no resin burr on the terminal top surface 41m, 51m, and the entire terminal top surface 41m, 51m is exposed. The positive terminal inner portion 42 is joined to and conductively connected to a positive electrode current collector portion 33 of the electrode body 30 described later inside the case 10. On the other hand, the negative electrode terminal inner portion 52 is joined to and electrically connected to a negative electrode current collecting portion 36 (described later) of the electrode body 30 inside the case 10 .

[0019] Next, the resin members 60 and 70 will be described. The positive electrode resin member 60 is bonded to the insertion hole surrounding portion 23 of the cover member 22 and the terminal member 40 while insulating the terminal member 40 from the annular insertion hole surrounding portion 23 of the cover member 22 that surrounds the insertion hole 22a of the cover member 22. The negative electrode resin member 70 is bonded to the insertion hole surrounding portion 24 of the cover member 22 and the terminal member 50 while insulating the terminal member 40 from the annular insertion hole surrounding portion 24 of the cover member 22 that surrounds the insertion hole 22b of the cover member 22. The negative electrode resin member 70 is bonded to the insertion hole surrounding portion 24 of the cover member 22 and the terminal member 50 while insulating the terminal member 50 from the annular insertion hole surrounding portion 24 of the cover member 22 that surrounds the insertion hole 22b of the cover member 22.

[0020] These resin members 60, 70 are made of polyphenylene sulfide (PPS) and have a resin outer frame portion 61, 71 located on the outside EH of the cover member 22, and a resin inner portion 62, 72 located inside the case 10 and in the insertion holes 22a, 22b of the cover member 22 and connected to the resin outer frame portion 61, 71. The resin outer frame portion 61, 71 is frame-shaped surrounding the periphery of the terminal outer flat plate portion 41, 51 of the terminal member 40, 50 and is flush with the terminal top surfaces 41m, 51m of the terminal outer flat plate portion 41, 51, and insulates between the terminal outer flat plate portion 41, 51 of the terminal member 40, 50 and the insertion hole surrounding portion 23, 24 of the cover member 22. On the other hand, the resin inner portions 62, 72 insulate between the terminal inner portions 42, 52 of the terminal members 40, 50 and the insertion hole surrounding portions 23, 24 of the cover member 22.

[0021] Next, the electrode body 30 will be described. The electrode body 30 is formed by stacking a strip-shaped positive electrode plate 31 and a strip-shaped negative electrode plate 34 with a pair of separators 37 in between, each of which is a strip-shaped resin porous film, rolling them up into a cylindrical shape, and then pressing them into a flat shape. The electrode body 30 is housed in the case 10 in a sideways state. The end of the electrode body 30 on one side BH1 in the battery width direction BH is a positive electrode current collector 33 in which the positive electrode current collector foil 32 of the positive electrode plate 31 protrudes in a spiral shape. The positive electrode current collector 33 is joined to the terminal inner part 42 of the positive electrode terminal member 40. The end of the electrode body 30 on the other side BH2 in the battery width direction BH is a negative electrode current collector 36 in which the negative electrode current collector foil 35 of the negative electrode plate 34 protrudes in a spiral shape. The negative electrode current collector 36 is joined to the terminal inner part 52 of the negative electrode terminal member 50.

[0022] Next, a method for manufacturing the battery 1 will be described (see Figs. 6 to 8). The lid member 22 and the terminal members 40, 50 are prepared in advance. The lid member 22 is obtained by punching an aluminum plate into a predetermined shape and forming the liquid injection hole 22k, the insertion holes 22a, 22b, and the safety valve 28. The positive electrode terminal member 40 is obtained by punching an aluminum plate and the negative electrode terminal member 50 is obtained by punching a copper plate into a predetermined shape and bending the same.

[0023] Then, in the "insert molding step S1" (see FIG. 6), the resin members 60, 70 are insert-molded with the terminal members 40, 50 inserted into the insertion holes 22a, 22b of the lid member 22, respectively, to form the lid assembly 7 (see FIGS. 7 and 8). Specifically, of the molding die DE (see FIG. 7) having an upper die DE1 and a lower die DE2, the lid member 22 is first placed at a predetermined position in the lower die DE2. Next, the terminal members 50, 60 are inserted into the insertion holes 22a, 22b of the lid member 22 placed in the lower die DE2, respectively. Thereafter, the upper die DE1 is moved downward and placed on top of the lower die DE2, and the molding die DE is closed.

[0024] A pair of injection nozzles NZ are arranged in the upper die DE1, and the molten resin MR can be injected from gates GT formed at the tip of each injection nozzle NZ into a pair of cavities CV formed by the cover member 22, the terminal members 40, 50, and the molding die DE. When the molding die DE is closed, the insertion holes 22a, 22b of the cover member 22, more specifically, the cutout portions 22a2, 22b2 of the insertion holes 22a, 22b, are located on the front face F (directly below in this embodiment) of each gate GT.

[0025] Next, the molten resin MR is injected from each gate GT into the gate-side space CV1 of the cavity CV on the gate GT side (upper in FIG. 7) of the cover member 22. The molten resin MR injected from the gate GT and proceeding downward flows through the cutouts 22a2, 22b2 into the counter-gate-side space CV2 of the cavity CV on the opposite side of the gate GT from the cover member 22 without being blocked by the cover member 22, because the cutouts 22a2, 22b2 are provided in the insertion holes 22a, 22b.

[0026] Therefore, even if the resin pressure is low, the molten resin MR can be smoothly distributed throughout the cavity CV. In addition, since the resin pressure can be low, it is possible to prevent a part of the molten resin MR supplied around the terminal outer flat plate portion 41, 51 of the terminal member 40, 50 from flowing further into between the terminal top surface 41m, 51m of the terminal outer flat plate portion 41, 51 and the upper mold DE1. Note that the appropriate resin pressure of the molten resin MR differs depending on the design of the battery, so it is set appropriately by conducting a preliminary experiment. Furthermore, the molten resin MR that has flowed into the counter-gate space CV2 of the cavity CV flows around the terminal back surfaces 41n, 51n of the terminal outer flat plate portions 41, 51 of the terminal members 40, 50, and presses the terminal outer flat plate portions 41, 51 from the terminal back surfaces 41n, 51n side against the upper die DE1, so that the terminal top surfaces 41m, 51m are in close contact with the upper die DE1. This effectively prevents the molten resin MR from flowing between the upper die DE1 and the terminal top surfaces 41m, 51m.

[0027] Thereafter, the molten resin MR filling the entire cavities CV is cooled to mold the resin members 60, 70 in the cavities CV. In this embodiment, the molten resin MR injected from the gate GT smoothly spreads throughout the cavities CV as described above, so that even if the resin pressure of the molten resin MR is reduced, the resin members 60, 70 without air bubbles can be molded. On the other hand, because the resin pressure can be reduced, deformation of the insertion hole surrounding portions 23, 24 of the cover member 22 can be prevented. Next, the upper mold DE1 is moved upward, and the lid assembly 7, in which the terminal members 40, 50 are fixed to the lid member 22 via the resin members 60, 70, is taken out from the lower mold DE2.

[0028] Next, in the "electrode body connection process S2" (see FIG. 6), the positive electrode plate 31, the negative electrode plate 34, and a pair of separators 37, each of which is in the shape of a belt, are wound and pressed into a flat shape to prepare the electrode body 30, and the terminal inner parts 42, 52 of the terminal members 40, 50 of the lid assembly 7 described above are ultrasonically welded to the positive electrode current collector 33 and the negative electrode current collector 36 of the electrode body 30, respectively (see FIGS. 1 and 2). Thereafter, the electrode body 30 is wrapped in a bag-shaped insulating holder 5.

[0029] Next, in the "electrode assembly housing / case forming process S3", a main body member 21 is prepared, the electrode assembly 30 covered with the insulating holder 5 described above is inserted into the main body member 21, and the opening 21c of the main body member 21 is closed with the lid member 22. Then, the opening 21c of the main body member 21 and the peripheral portion of the lid member 22 are laser welded over the entire periphery to form the case 10 housing the electrode assembly 30 therein.

[0030] Next, in a "pouring and sealing process S4", the electrolyte 3 is poured into the case 10 through the pouring hole 22k, and the electrolyte 3 is impregnated into the electrode body 30. Thereafter, the pouring hole 22k is covered from the outside with a sealing member 29, and the sealing member 29 is laser welded to the lid member 22 to hermetically seal the gap between the sealing member 29 and the lid member 22. Next, in the "initial charging and aging step S5", a charging device (not shown) is connected to the battery 1 to perform an initial charge on the battery 1. After that, the initially charged battery 1 is left to stand for a predetermined time to age the battery 1. In this way, the battery 1 is completed.

[0031] As described above, in the manufacturing method of the battery 1, in the insert molding step S1, the insertion holes 22a, 22b of the cover member 22 are positioned on the front face F of the gate GT, and the molten resin MR injected from the gate GT is poured into the non-gate side space CV2 of the cavity CV through the insertion holes 22a, 22b and spreads throughout the entire cavity CV, so that the molten resin MR can be smoothly spread throughout the entire cavity CV. Therefore, even if the resin pressure of the molten resin MR is reduced, the resin members 60, 70 without bubbles inside can be molded. On the other hand, since the resin pressure can be reduced, deformation of the insertion hole surrounding parts 23, 24 of the cover member 22 can be prevented. Thus, the battery 1 without bubbles inside the resin members 60, 70 and without deformation of the cover member 22 can be manufactured.

[0032] In this embodiment, the insertion holes 22a, 22b provided in the cover member 22 have insertion portions 22a1, 22b1 through which the terminal members 40, 50 are inserted, and notches 22a2, 22b2 extending from the insertion portions 22a1, 22b1. Therefore, compared to a case in which the overall shape of the insertion holes is a rectangular or elliptical shape, the insertion holes 22a, 22b can be made smaller, and the resin members 60, 70 can be made smaller. Even though the insertion holes 22a, 22b and the resin members 60, 70 are small, a battery 1 can be manufactured in which there are no air bubbles inside the resin members 60, 70 and the cover member 22 is not deformed.

[0033] In addition, in this embodiment, since the resin pressure of the molten resin MR can be reduced, a part of the molten resin MR supplied around the terminal outer flat plate portion 41, 51 can be prevented from flowing further into the gap between the terminal top surface 41m, 51m of the terminal outer flat plate portion 41, 51 and the upper mold DE1. Furthermore, the molten resin MR flowing into the counter-gate side space CV2 of the cavity CV flows around the terminal back surface 41n, 51n of the terminal outer flat plate portion 41, 51 and presses the terminal outer flat plate portion 41, 51 against the upper mold DE1 from the terminal back surface 41n, 51n side, so that the terminal top surface 41m, 51m is in close contact with the upper mold DE1. Therefore, the molten resin MR can be effectively prevented from flowing into the gap between the upper mold DE1 and the terminal top surface 41m, 51m.

[0034] Although the present invention has been described above with reference to an embodiment, it goes without saying that the present invention is not limited to the embodiment and can be modified as appropriate without departing from the spirit of the present invention. For example, in the embodiment, the cutout portions 22a2, 22b2 are provided in the insertion holes 22a, 22b of the cover member 22, and in the insert molding step S1, the cutout portions 22a2, 22b2 of the insertion holes 22a, 22b are positioned on the front surface F of the gate GT, but this is not limited thereto. For example, the insertion portions through which the terminal members 40, 50 are inserted may be extended in the battery width direction BH to enlarge the entire insertion hole, thereby positioning the insertion hole on the front surface F of the gate GT. [Explanation of symbols]

[0035] 1. Battery (energy storage device) 10 Cases 21 Main body parts 22 Lid member (case member) 22a, 22b Insertion holes 22a1, 22b1 Insertion part 22a2, 22b2 Notch 30 Electrode body 40,50 Terminal material 41,51 Terminal outer flat plate part 41m, 51m Terminal top 41n,51n back side of terminal 60,70 Resin material 61,71 Resin outer frame EH (Outside of cover) DE molding die GT Gate CV Cavity CV1 Gate side space CV2 Opposite gate side space F (front of gate) MR Melt Resin

Claims

1. A case member having an insertion hole; a terminal member inserted into the insertion hole of the case member; and a resin member that is bonded to the case member and the terminal member while insulating the case member and the terminal member, and fixes the terminal member to the case member. A method for manufacturing an electricity storage device, comprising: The insertion hole is an insertion portion through which the terminal member is inserted; and a notch portion extending from the insertion portion, an insert molding step of insert-molding the resin member in a state where the terminal member is inserted into the insertion hole of the case member, The insert molding process includes: the notch portion of the insertion hole of the case member is positioned in front of a gate for injecting molten resin into a cavity formed by the case member, the terminal member, and a molding die; The molten resin injected from the gate is poured through the insertion hole into a space on the opposite side of the cavity from the gate relative to the case member, and is allowed to permeate the entire cavity to form the resin member. A method for manufacturing an electricity storage device.

2. A method for producing the electricity storage device according to claim 1, comprising the steps of: The terminal member is a terminal outer flat plate portion located outside the case member and including an exposed flat terminal top surface; The resin member is a resin outer frame portion that is positioned on the outside of the case member, that is frame-shaped and surrounds the periphery of the terminal outer flat plate portion of the terminal member, and that is flush with the terminal top surface of the terminal outer flat plate portion; A method for manufacturing an electricity storage device.

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