JP2020173921A - Method of manufacturing power storage module - Google Patents

Abstract

To provide a method of manufacturing a power storage module that can suppress joint failure and deterioration in productivity due to hot plate welding.SOLUTION: A method of manufacturing a power storage module 4 includes a welding step of joining and integrating a module main body 20 having a seal member 12 and a pressure regulating valve 23 having a case 29 by hot plate welding. The welding step uses a hot plate welding device 100 including a hot plate main body 101, and a thin plate-shaped cover plate 102 which is detachably attached to the hot plate main body 101, and made of a rigid body having high thermal conductivity. When each of a joining protrusion 27 of the sealing member 12 and a joining protrusion 34 of the case 29 is brought into contact with an outer surface 102a of the cover plate 102 and each of the joining protrusions 27 and 34 is heated and melted by a preset melting amount, the joining protrusions 27 and 34 are separated from the outer surface 102a of the cover plate 102, and then the joining protrusion 27 and the joining protrusion 34 are brought into contact with each other under pressure.SELECTED DRAWING: Figure 6

Description

The present disclosure relates to a method for manufacturing a power storage module.

As a power storage module, for example, a module including an electrode laminate in which a plurality of electrodes are laminated via a separator and a case for holding the electrode laminate are known. A storage space for accommodating the electrolytic solution is formed between adjacent electrodes of the electrode laminate. In such a power storage module, the electrolytic solution is injected into the accommodation space through the liquid injection port provided in the case. Then, after the injection of the electrolytic solution, a sealing member is attached to the liquid injection port, and the power storage module is sealed.

When the case and the sealing member are made of resin, for example, hot plate welding is adopted as a method of attaching the resin sealing member to the resin case. In hot plate welding, each welded surface of the case and the sealing member is brought into contact with the molten surface of the hot plate to be melted, and then the welded surfaces are cooled while being in pressure contact with each other to cool the case and the sealing member. Is joined and integrated. At this time, a part of the welded resin remains attached to the molten surface of the hot plate, but if the adhered resin becomes a foreign substance due to carbonization or the like, it may cause a bonding failure in the subsequent hot plate welding. , It is necessary to replace the hot plate on a regular basis.

Patent Document 1 describes that a protective tape is arranged between the hot plate and the separator in a method of forming a joint portion of the electrode plate separator by hot plate welding. As a result, it is possible to prevent the burnt residue or melt residue of the separator from adhering to the hot plate, so that the replacement time of the hot plate can be reduced and the deterioration of productivity can be suppressed.

JP-A-2002-260625

When the resin sealing member is attached to the resin case by hot plate welding using the protective tape as described above, the surface accuracy of the molten surface may be substantially lowered because the protective tape is soft. As a result, the amount of melting of the case and the sealing member varies, which may cause poor joining.

Therefore, it is an object of the present invention to provide a method for manufacturing a power storage module capable of suppressing joint failure and deterioration of productivity due to hot plate welding.

The method for manufacturing a power storage module of the present disclosure is a method for manufacturing a power storage module having an electrode laminate in which a plurality of electrodes are laminated via a separator, and includes a module main body having an electrode laminate and a first resin portion, and a first. 2 Including a welding step of joining and integrating a welded member having a resin portion by hot plate welding, in the welding step, the hot plate main body in which the heat generating portion is arranged and the hot plate main body are detachably attached. Using a hot plate welding device equipped with a thin plate-shaped cover plate made of a rigid body with high thermal conductivity, the first resin part and the second resin part are brought into contact with the molten surface of the cover plate, respectively, and the first resin part and the second resin part are brought into contact with each other. When each part is heated and melted by a preset amount of melting, the first resin part and the second resin part are separated from the molten surface of the cover plate, and then the first resin part and the second resin part are brought into pressure contact with each other. Let me.

In this method of manufacturing the power storage module, since the hot plate body is covered with the cover plate, it is possible to prevent the resin from adhering to the hot plate body. Therefore, it is possible to reduce the replacement time of the hot plate main body and suppress the deterioration of productivity. Moreover, since the cover plate is made of a rigid body having high thermal conductivity, it is possible to prevent the heat of the hot plate body from being blocked and to prevent the surface accuracy of the molten surface from being lowered. Therefore, the melt amounts of the first resin portion and the second resin portion are unlikely to vary. Therefore, poor bonding due to hot plate welding can be suppressed. As described above, it is possible to suppress joint failure and deterioration of productivity due to hot plate welding.

The method of manufacturing the power storage module of the present disclosure is a replacement step of removing the used cover plate attached to the hot plate body of the hot plate welding device and attaching an unused or unused cover plate after cleaning before the welding step. May be further included. When the first resin portion and the second resin portion are melted by the cover plate in which the resin remains on the molten surface, foreign matter may be mixed in the molten resin and a bonding failure may occur. In this method of manufacturing a power storage module, since the used cover plate is removed and an unused cover plate is attached before the welding process, it is possible to suppress the occurrence of bonding defects due to residual resin.

The cover plate is formed of a metal material having a thermal conductivity equal to or higher than that of the hot plate body, and the molten surface may be formed as a flat surface. In this case, since the cover plate is formed of a metal material, the heat transfer property and strength of the cover plate are improved. Further, since the molten surface is formed as a flat surface, the variation in the melted amount of the first resin portion and the second resin portion is surely suppressed. Therefore, poor bonding due to hot plate welding can be reliably suppressed.

The cover plate may be fixed to the hot plate body by bolts. In this case, the heat transfer property between the hot plate and the cover plate can be enhanced through the bolt.

The welded member may be a pressure adjusting valve for adjusting the pressure in the internal space provided between the adjacent electrodes of the module body. In this case, it is possible to sufficiently suppress poor joining between the module body and the pressure regulating valve due to hot plate welding.

The first resin portion is provided with a first communication hole that communicates with the internal space, the second resin portion is provided with a second communication hole, and in the welding process, the first communication hole and the second communication hole are provided. The first resin portion and the second resin portion may be joined by hot plate welding so as to communicate with each other. In hot plate welding between the module body and the pressure regulating valve, for example, if the amount of melting is too large, the first communication hole and the second communication hole may be blocked by the molten resin. Further, for example, if the amount of melting is too small, the first communication hole and the second communication hole cannot be joined without a gap. In this method of manufacturing the power storage module, it is possible to suppress a decrease in the surface accuracy of the molten surface, so that the amount of melting of the first resin portion and the second resin portion is unlikely to vary. Therefore, it is possible to suppress the blockage of the first communication hole and the second communication hole, and it is possible to join the first communication hole and the second communication hole without a gap.

According to the present disclosure, it is possible to provide a method for manufacturing a power storage module capable of suppressing joint failure and deterioration of productivity due to hot plate welding.

It is the schematic sectional drawing which shows the power storage device which includes the power storage module which concerns on embodiment. It is the schematic sectional drawing which shows the internal structure of the power storage module. It is a schematic perspective view of a power storage module. It is an exploded perspective view (including a partial sectional view) which shows a part of a power storage module. It is a schematic perspective view which shows the hot plate welding apparatus used in the manufacturing method of the power storage module which concerns on embodiment. It is a figure for demonstrating the process of melting the joint protrusion of a pressure control valve. It is a figure for demonstrating the process of melting the bonding protrusion of a module body.

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same reference numerals are used for the same or equivalent elements, and duplicate description is omitted.

Hereinafter, embodiments of a method for manufacturing a power storage module according to one aspect of the present disclosure will be described in detail with reference to the drawings.

FIG. 1 is a schematic cross-sectional view showing a power storage device including the power storage module according to the embodiment. The power storage device 1 shown in FIG. 1 is used as a battery for various vehicles such as forklifts, hybrid vehicles, and electric vehicles. The power storage device 1 includes a module stack 2 including a plurality of stacked power storage modules 4, and a restraint member 3 that applies a restraint load to the module stack 2 in the stacking direction (Z-axis direction) of the module stack 2. It has.

The module laminate 2 includes a plurality of (three in this case) power storage modules 4 and a plurality of (four in this case) conductive plates 5. The power storage module 4 is a bipolar battery and has a rectangular shape when viewed from the stacking direction. The power storage module 4 is, for example, a secondary battery such as a nickel hydrogen secondary battery or a lithium ion secondary battery, or an electric double layer capacitor. In the following description, a nickel hydrogen secondary battery will be illustrated.

The power storage modules 4 adjacent to each other in the stacking direction are electrically connected to each other via the conductive plate 5. The conductive plates 5 are arranged between the storage modules 4 adjacent to each other in the stacking direction and outside the power storage modules 4 located at the stacking ends. A positive electrode terminal 6 is connected to one of the conductive plates 5 arranged outside the power storage module 4 located at the laminated end. The negative electrode terminal 7 is connected to the other conductive plate 5 arranged outside the power storage module 4 located at the laminated end. The positive electrode terminal 6 and the negative electrode terminal 7 are drawn out from the edge of the conductive plate 5, for example, in a direction intersecting the stacking direction. The positive electrode terminal 6 and the negative electrode terminal 7 charge and discharge the power storage device 1.

The conductive plate 5 is provided with a plurality of flow paths 5a through which a cooling fluid such as air flows. The flow path 5a extends along a direction that intersects (orthogonally), for example, the stacking direction and the drawing direction of the positive electrode terminal 6 and the negative electrode terminal 7. The conductive plate 5 has a function as a connecting member that electrically connects the power storage modules 4 to each other. Further, the conductive plate 5 also has a function as a heat radiating plate that dissipates heat generated by the power storage module 4 by flowing a cooling fluid through these flow paths 5a. In the example of FIG. 1, the area of the conductive plate 5 seen from the stacking direction is smaller than the area of the power storage module 4, but from the viewpoint of improving heat dissipation, the area of the conductive plate 5 is the area of the power storage module 4. It may be the same as the area, and may be larger than the area of the power storage module 4.

The restraint member 3 is composed of a pair of end plates 8 that sandwich the module laminate 2 in the stacking direction, and fastening bolts 9 and nuts 10 that fasten the end plates 8 to each other. The end plate 8 is a rectangular metal plate having an area one size larger than the area of the power storage module 4 and the conductive plate 5 when viewed from the stacking direction. A film F having electrical insulation is provided on the surface of the end plate 8 on the module laminate 2 side. The film F insulates between the end plate 8 and the conductive plate 5.

An insertion hole 8a is provided at the edge of the end plate 8 at a position outside the module laminate 2. The fastening bolt 9 is passed from the insertion hole 8a of one end plate 8 toward the insertion hole 8a of the other end plate 8. A nut 10 is screwed into the tip portion of the fastening bolt 9 protruding from the insertion hole 8a of the other end plate 8. As a result, the power storage module 4 and the conductive plate 5 are sandwiched by the end plates 8 and unitized as the module laminate 2. Further, a restraining load is applied to the module laminated body 2 in the laminating direction.

Next, the configuration of the power storage module 4 will be described in detail. FIG. 2 is a schematic cross-sectional view showing the internal configuration of the power storage module shown in FIG. FIG. 3 is a schematic perspective view of the power storage module. FIG. 4 is an exploded perspective view (including a partial cross-sectional view) showing a part of the power storage module 4. As shown in FIGS. 2 to 4, the power storage module 4 includes a module main body 20 and a plurality of pressure regulating valves 23 (welded members) welded to the module main body 20 (here, four). There is.

The module main body 20 includes an electrode laminate 11 and a resin sealing member 12 (first resin portion) that seals the electrode laminate 11. The electrode laminate 11 is composed of a plurality of electrodes laminated via a separator 13. These electrodes include a laminate of a plurality of bipolar electrodes 14, a negative electrode termination electrode 18, and a positive electrode termination electrode 19.

The bipolar electrode 14 has an electrode plate 15 including one surface 15a and the other surface 15b on the opposite side of the one surface 15a, a positive electrode 16 provided on the one surface 15a, and a negative electrode 17 provided on the other surface 15b. ing. The positive electrode 16 is a positive electrode active material layer formed by coating the electrode plate 15 with the positive electrode active material. The negative electrode 17 is a negative electrode active material layer formed by coating the electrode plate 15 with the negative electrode active material. In the electrode laminate 11, the positive electrode 16 of one bipolar electrode 14 faces the negative electrode 17 of another bipolar electrode 14 adjacent to one of the stacking directions (Z-axis direction) with the separator 13 interposed therebetween. In the electrode laminate 11, the negative electrode 17 of one bipolar electrode 14 faces the positive electrode 16 of another bipolar electrode 14 adjacent to the other in the stacking direction with the separator 13 interposed therebetween.

The negative electrode terminal electrode 18 has an electrode plate 15 and a negative electrode 17 provided on the other surface 15b of the electrode plate 15. The negative electrode terminal electrode 18 is arranged at one end in the stacking direction so that the other surface 15b faces the center side of the electrode stack 11 in the stacking direction. One surface 15a of the electrode plate 15 of the negative electrode terminal electrode 18 constitutes one outer surface in the stacking direction of the electrode laminate 11, and is electrically connected to one conductive plate 5 (see FIG. 1) adjacent to the power storage module 4. It is connected. The negative electrode 17 provided on the other surface 15b of the electrode plate 15 of the negative electrode terminal electrode 18 faces the positive electrode 16 of the bipolar electrode 14 at one end in the stacking direction via the separator 13.

The positive electrode terminal electrode 19 has an electrode plate 15 and a positive electrode 16 provided on one surface 15a of the electrode plate 15. The positive electrode terminal electrode 19 is arranged at the other end in the stacking direction so that one surface 15a faces the center side of the electrode stack 11 in the stacking direction. The positive electrode 16 provided on one surface 15a of the positive electrode terminal electrode 19 faces the negative electrode 17 of the bipolar electrode 14 at the other end in the stacking direction via the separator 13. The other surface 15b of the electrode plate 15 of the positive electrode terminal electrode 19 constitutes the other outer surface in the stacking direction of the electrode laminate 11, and is electrically connected to the other conductive plate 5 (see FIG. 1) adjacent to the power storage module 4. It is connected.

The electrode plate 15 is made of, for example, a metal plate such as a nickel plate whose surface is plated or a steel plate whose surface is plated. Here, the electrode plate 15 is made of a plated steel plate obtained by plating the surface of the steel plate with nickel. As the steel sheet used as the base material of the plated steel sheet, for example, ordinary steel such as rolled steel or special steel such as stainless steel is used. The edge portion 15c of the electrode plate 15 has a rectangular frame shape, and is an uncoated region in which the positive electrode active material and the negative electrode active material are not coated. Examples of the positive electrode active material constituting the positive electrode 16 include nickel hydroxide. Examples of the negative electrode active material constituting the negative electrode 17 include a hydrogen storage alloy. In the present embodiment, the formation region of the negative electrode 17 on the other surface 15b of the electrode plate 15 is slightly larger than the formation region of the positive electrode 16 on the one surface 15a of the electrode plate 15.

The separator 13 is formed in a sheet shape, for example. Examples of the separator 13 include a porous film made of a polyolefin resin such as polyethylene (PE) and polypropylene (PP), a woven fabric made of polypropylene, methyl cellulose and the like, or a non-woven fabric. The separator 13 may be reinforced with a vinylidene fluoride resin compound.

The seal member 12 is formed in a rectangular tubular shape as a whole by, for example, an insulating resin. The sealing member 12 is arranged on the side surface 11a of the electrode laminate 11 so as to surround the edge portion 15c of the electrode plate 15. The seal member 12 holds the edge portion 15c on the side surface 11a. The seal member 12 surrounds the plurality of primary seals 21 coupled to the edge portion 15c of the electrode plate 15 from the outside and the primary seal 21 along the side surface 11a from the outside, and is coupled to each of the primary seals 21. And have. The primary seal 21 and the secondary seal 22 are, for example, alkali-resistant insulating resins. Examples of the constituent materials of the primary seal 21 and the secondary seal 22 include polypropylene (PP), polyphenylene sulfide (PPS), and modified polyphenylene ether (modified PPE).

The primary seal 21 is continuously provided on one surface 15a of the electrode plate 15 over the entire circumference of the edge portion 15c, and has a rectangular frame shape when viewed from the stacking direction. In the present embodiment, the primary seal 21 is provided not only on the electrode plate 15 of the bipolar electrode 14, but also on the electrode plate 15 of the negative electrode terminal 18 and the electrode plate 15 of the positive electrode 19. In the negative electrode terminal electrode 18, a primary seal 21 is provided on the edge 15c of the one surface 15a of the electrode plate 15, and in the positive electrode terminal 19, the primary seal 21 is provided on both the edges 15c of the one surface 15a and the other surface 15b of the electrode plate 15. A seal 21 is provided.

The primary seal 21 is welded to one surface 15a of the electrode plate 15 by, for example, ultrasonic waves or thermocompression bonding, and is airtightly bonded. The primary seal 21 is, for example, a film having a predetermined thickness in the stacking direction. The inside of the primary seal 21 is located between the edge portions 15c of the electrode plates 15 adjacent to each other in the stacking direction. The outside of the primary seal 21 projects outward from the edge of the electrode plate 15, and the tip portion thereof is held by the secondary seal 22. The primary seals 21 adjacent to each other along the stacking direction may be separated from each other or may be in contact with each other. Further, the outer edge portions of the primary seal 21 may be bonded to each other by, for example, hot plate welding.

The secondary seal 22 is provided on the outside of the electrode laminate 11 and the primary seal 21, and constitutes an outer wall (housing) of the power storage module 4. The secondary seal 22 is formed by, for example, injection molding of a resin, and extends over the entire length of the electrode laminate 11 along the lamination direction. The secondary seal 22 has a rectangular frame shape extending in the axial direction in the stacking direction. The secondary seal 22 is welded to the outer surface of the primary seal 21 by, for example, heat during injection molding.

The primary seal 21 and the secondary seal 22 form an internal space V between adjacent electrodes and seal the internal space V. More specifically, the secondary seal 22, together with the primary seal 21, is between the bipolar electrodes 14 adjacent to each other along the stacking direction, and between the negative electrode termination electrodes 18 and the bipolar electrodes 14 adjacent to each other along the stacking direction. , And the positive electrode terminal 19 and the bipolar electrode 14 adjacent to each other along the stacking direction are sealed. As a result, an airtightly partitioned internal space V is formed between the adjacent bipolar electrodes 14, between the negative electrode terminal 18 and the bipolar electrode 14, and between the positive electrode 19 and the bipolar electrode 14. ing. An aqueous electrolytic solution (not shown) containing an alkaline solution such as an aqueous potassium hydroxide solution is housed in the internal space V. The electrolytic solution is impregnated in the separator 13, the positive electrode 16, and the negative electrode 17.

In the present embodiment, the electrode plate 15 constituting the negative electrode termination electrode 18 and the electrode plate 15 constituting the positive electrode termination electrode 19 correspond to a metal plate located in the outermost layer. In the negative electrode terminal electrode 18, one surface 15a side of the electrode plate 15 is a surface that comes into contact with the atmosphere, and in the positive electrode terminal electrode 19, the other surface 15b side of the electrode plate 15 is a surface that comes into contact with the atmosphere. Therefore, in the negative electrode terminal electrode 18, it is preferable that at least the surface on the one side 15a side of the electrode plate 15 is alkaline, and in the positive electrode terminal electrode 19, at least the surface on the other surface 15b side of the electrode plate 15 is alkaline. It is preferable to exhibit.

One wall portion 12a constituting the seal member 12 is provided with a plurality of (here, four) mounting regions 24 to which the pressure adjusting valve 23 is mounted. Each mounting area 24 is provided with a plurality of (six in this case) communication holes 25. The communication holes 25 are arranged in three rows and two stages (three rows in the Y-axis direction and two stages in the Z-axis direction) in each mounting region 24. Therefore, the communication holes 25 are arranged in 12 rows and 2 steps on the wall portion 12a. Each communication hole 25 communicates with the internal space V of a different cell.

Each mounting area 24 of the secondary seal 22 is provided with a plurality of (six in this case) communication holes 26 (first communication holes) that are communicated with each communication hole 25. The communication holes 26 are arranged in three rows and two stages in each mounting region 24.

The communication holes 25 and 26 function as liquid injection holes for injecting the electrolytic solution into the internal space V. Further, the communication holes 25 and 26 serve as a flow path through which the gas generated in the internal space V flows after the electrolytic solution is injected.

The seal member 12 has a substantially frame-shaped joining protrusion 27 provided on the outer surface of each mounting region 24 of the secondary seal 22. The joining protrusion 27 attaches the pressure adjusting valve 23 to the module main body 20, and forms a plurality of (six in this case) flow paths 28 through which gas from each internal space V flows in cooperation with the communication holes 26. .. Therefore, the flow paths 28 are arranged in three rows and two stages in each mounting region 24. The flow path 28 has a rectangular shape in a cross section along a plane perpendicular to the X-axis direction. The bonding protrusions 27 are formed in a grid pattern when viewed from the X-axis direction.

As shown in FIG. 4, the pressure regulating valve 23 has a case 29 (second resin portion), a plurality of (six in this case) valve bodies 30, and a cover 31. The pressure adjusting valve 23 adjusts the pressure in the internal space V of the electrode laminate 11.

The case 29 is an injection-molded resin product, and is made of a resin such as PP, PPS, or modified PPE. The case 29 is formed in a substantially rectangular shape when viewed from the opposite direction (X-axis direction) in which the case 29 and the cover 31 face each other. The case 29 has a bottom wall portion 32. The bottom wall portion 32 is provided with a plurality of (six in this case) communication holes 33 (second communication holes) that are communicated with each communication hole 26 of the module main body 20. The communication hole 33 has a circular shape with a cross section along a plane (YZ plane) perpendicular to the X-axis direction. The communication hole 33 penetrates the bottom wall portion 32.

The case 29 has a substantially frame-shaped joining protrusion 34 provided on the outer wall surface 32a of the bottom wall portion 32. The joining protrusion 34 joins the module main body 20 and the pressure regulating valve 23, and forms a plurality of (six in this case) flow paths 35 through which gas from each internal space V flows. The joining protrusion 34 is joined to the joining protrusion 27 of the module main body 20. The joining protrusion 34 has a shape and dimensions corresponding to the joining protrusion 27. Therefore, the flow path 35 has a rectangular shape in a cross section along a plane (YZ plane) perpendicular to the X-axis direction. Further, the bonding protrusions 34 are formed in a grid pattern when viewed from the X-axis direction.

The case 29 has a side wall portion 36 and a partition wall portion 37 protruding from the bottom wall portion 32 toward the cover 31, respectively. In the present embodiment, the side wall portion 36 and the partition wall portion 37 are integrally formed with the bottom wall portion 32. The side wall portions 36 are erected on the edge of the inner wall surface of the bottom wall portion 32 so as to surround a plurality of (six in this case) valve bodies 30. The partition wall portion 37 is erected on the inner wall surface of the bottom wall portion 32 so as to cover the side surface of each valve body 30. When the cover 31 is attached to the case 29, the cover 31 and the partition wall portion 37 are separated from each other. The space between the cover 31 and the partition wall portion 37 functions as a flow path for the gas that has flowed into the pressure regulating valve 23 from the internal space V.

The valve body 30 is housed in the case 29 so as to close the communication hole 33. The valve body 30 is a columnar member formed of an elastic body such as rubber. The valve body 30 is arranged in a state of being pressed against the bottom wall portion 32 by the cover 31 to close the communication hole 33. The valve body 30 opens and closes the communication hole 33 according to the pressure of the internal space V. A gap is provided between the side surface of the valve body 30 and the partition wall portion 37 or the side wall portion 36. This gap functions as a flow path for the gas that has flowed into the pressure regulating valve 23 from the internal space V.

The cover 31 is a plate-shaped member that closes the opening of the case 29. The cover 31 is made of a resin such as PP, PPS or modified PPE. The cover 31 is joined to the open end face of the case 29 by welding. The cover 31 is joined to the open end surface of the case 29 while maintaining the state in which the valve body 30 is pressed against the bottom wall portion 32 of the case. The cover 31 is joined, for example, to the end of the side wall portion 36 by, for example, ultrasonic welding. The cover 31 is provided with an exhaust port 41 for exhausting the gas inside the pressure regulating valve 23 to the outside of the pressure regulating valve 23. The exhaust port 41 is arranged so as not to overlap the valve body 30 when viewed from the opposite direction.

In the pressure regulating valve 23, the communication hole 33 of the case 29 is communicated with the internal space V of the module main body 20 through the communication hole 26 of the secondary seal 22 and the communication hole 25 of the primary seal 21. When the pressure in the internal space V is lower than the set pressure, the communication hole 33 is maintained in a closed state in which the valve body 30 is closed. When the pressure in the internal space V rises to exceed the set pressure, the valve body 30 is elastically deformed so as to be separated from the bottom wall portion 32, and the valve opening state in which the communication hole 33 is released is released. As a result, the gas from the internal space V flows to the space formed between the partition wall portion 37 and the cover 31 through the gap between the side surface of the valve body 30 and the inner wall surface of the partition wall portion 37. Then, the gas is exhausted from the space between the partition wall 37 and the cover 31 to the outside of the pressure regulating valve 23 via the exhaust port 41.

Next, a method of manufacturing the power storage module 4 will be described. The method of manufacturing the power storage module 4 is a welding step of joining and integrating the joining protrusion 27 of the module main body 20 and the joining protrusion 34 of the pressure regulating valve 23 by hot plate welding, and a replacement step of replacing the cover plate 102. And, including.

FIG. 5 is a schematic perspective view showing a hot plate welding device used in the method for manufacturing a power storage module according to an embodiment. As shown in FIG. 5, the hot plate welding device 100 includes a hot plate main body 101, a cover plate 102, a plurality of bolts 103, a heater 104 (heat generating portion), and a pair of temperature sensors 105. The hot plate body 101 is, for example, a rectangular plate member. The hot plate main body 101 has, for example, a rectangular melting surface 101a and a side surface 101b adjacent to the melting surface 101a. The hot plate body 101 is made of, for example, a metal such as iron or stainless steel.

The cover plate 102 is a thin plate-like member made of a rigid body having high thermal conductivity. The cover plate 102 has, for example, a rectangular shape when viewed from the thickness direction. The cover plate 102 has, for example, the same degree of thermal conductivity as the hot plate main body 101. The cover plate 102 is formed of, for example, a metal plate having a flat surface as a molten surface. The cover plate 102 is formed of a metal material having the same thermal conductivity as the hot plate main body 101 or higher than the hot plate main body 101. For example, an iron plate, a stainless steel plate, a copper plate, an aluminum plate, a heat-resistant aluminum alloy plate, etc. Is formed by. The cover plate 102 is detachably attached to the hot plate main body 101. The cover plate 102 is fixed to the molten surface 101a of the hot plate main body 101 by a plurality of (four in this case) bolts 103. The bolts 103 are provided at the four corners of the cover plate 102 when viewed from the thickness direction of the cover plate 102. The cover plate 102 may be fixed to the hot plate main body 101 by a fixing member other than the bolt 103.

The cover plate 102 is attached to the hot plate main body 101 so that the thickness directions of the cover plate 102 and the hot plate main body 101 coincide with each other. The cover plate 102 is thinner than the hot plate body 101, for example, and the thickness of the cover plate 102 is, for example, 5 mm. The cover plate 102 covers the entire surface of the molten surface 101a of the hot plate main body 101. Therefore, the outer surface 102a of the cover plate 102 is a substantially molten surface. When viewed from the thickness direction of the cover plate 102 and the hot plate main body 101, the cover plate 102 and the hot plate main body 101 have, for example, the same shape as each other.

The heater 104 is, for example, a cartridge heater. The heater 104 is arranged on the hot plate main body 101 and heats the hot plate main body 101. An insertion port 101c into which the heater 104 is inserted is provided on the side surface 101b of the hot plate main body 101. The heater 104 is inserted into the inside of the hot plate main body 101 from the insertion port 101c.

The pair of temperature sensors 105 detect the temperature of the hot plate main body 101. The temperature sensor 105 is, for example, a thermocouple. A pair of insertion ports 101d into which a pair of temperature sensors 105 are inserted are provided on the side surface 101b of the hot plate main body 101. A pair of insertion ports 101d are provided on both sides of the insertion port 101c on the side surface 101b. The pair of temperature sensors 105 are inserted into the inside of the hot plate main body 101 from the pair of insertion ports 101d. The pair of temperature sensors 105 may be arranged on the outer surface 102a of the cover plate 102, which is a substantially molten surface, and may detect the temperature of the outer surface 102a. One of the pair of temperature sensors 105 is a reserve in case of failure. The hot plate welding device 100 does not have to include a spare temperature sensor 105.

The heater 104 and the pair of temperature sensors 105 are each connected to a control circuit (not shown) that controls the hot plate welding device 100. The control circuit includes, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory). In this case, the control circuit loads the program stored in the ROM into the RAM and executes it on the CPU to perform various processes.

The welding step includes a step of melting the joining protrusion 27, a step of melting the joining protrusion 34, and a step of joining the melted joining protrusions 27 and 34 to each other.

FIG. 6 is a diagram for explaining a process of melting the joining protrusion of the pressure regulating valve. In FIG. 6, the temperature sensor 105 (see FIG. 5) is not shown. As shown in FIG. 6, the joining protrusion 34 of the pressure regulating valve 23 is melted by the hot plate welding device 100. For example, here, the pressure adjusting valve 23 is gripped by using the robot hand 110 having a pair of gripping portions 111, and in that state, the pressure adjusting valve 23 is moved onto the hot plate welding device 100 by the robot hand 110. The tip surface (welding surface) of the joining protrusion 34 of the pressure adjusting valve 23 is brought into contact with the outer surface 102a of the cover plate 102 to be melted. At this time, the joining protrusion 34 is pushed against the outer surface 102a. The pushing amount of the joining protrusion 34 (the melting amount of the joining protrusion 34) is set in advance. The amount of melt of the bonding protrusion 34 is, for example, 0.5 mm. As a result, even if there is a manufacturing error in the shape of the joining protrusion 34, the tip surface of the joining protrusion 34 can be flattened. When the joining protrusion 34 is heated and melted by a preset amount of melting, the robot hand 110 separates the joining protrusion 34 from the outer surface 102a of the cover plate 102.

FIG. 7 is a diagram for explaining a process of melting the joining protrusions of the module body. In FIG. 7, the temperature sensor 105 (see FIG. 5) is not shown. As shown in FIG. 7, the joining protrusion 27 of the module body 20 is melted by the hot plate welding device 100. For example, here, with the hot plate welding device 100 attached to the robot hand 120, the hot plate welding device 100 is moved onto the module main body 20 by the robot hand 120, and the outer surface 102a of the cover plate 102 is moved to the module main body 20. It is brought into contact with the tip surface (welding surface) of the bonding protrusion 27 to be melted. At this time, the joining protrusion 27 is pushed against the outer surface 102a. The pushing amount of the joining protrusion 27 (the melting amount of the joining protrusion 27) is set in advance. The amount of melt of the bonding protrusion 27 is, for example, 0.5 mm. As a result, even if there is a manufacturing error in the shape of the joining protrusion 27, the tip surface of the joining protrusion 27 can be flattened. When the joining protrusion 27 is heated and melted by a preset amount of melting, the robot hand 120 separates the joining protrusion 27 from the outer surface 102a of the cover plate 102. The module body 20 may be moved by a robot hand.

The step of melting the joining protrusion 27 and the step of melting the joining protrusion 34 are performed at the same time using, for example, two hot plate welding devices 100. Subsequently, a step of joining the molten joining protrusions 27 and 34 to each other is performed. In this step, the joining protrusions 27 and the joining protrusions 34 are brought into pressure contact with each other while the joining protrusions 27 and 34 are melted. For example, the pressure adjusting valve 23 is moved onto the module body 20 by the robot hand 110, and the tip surface of the joining protrusion 34 is pressed against the tip surface of the joining protrusion 27. As a result, the joining protrusions 27 and 34 are joined to each other. As described above, the pressure adjusting valve 23 is welded to the module main body 20, and the module main body 20 and the pressure adjusting valve 23 are integrated.

The exchange step is carried out, for example, every time the welding step is repeated a plurality of times. Specifically, after the welding step is repeated a plurality of times and before the new welding step, the used (old) cover plate 102 attached to the hot plate main body 101 of the hot plate welding device 100 is attached. It is removed from the hot plate body 101 together with the bolt 103, and an unused (new) cover plate 102 is attached to the hot plate body 101 by the bolt 103. The unused cover plate 102 may be a used cover plate 102 that has been cleaned and reused.

Next, the operation and effect of the manufacturing method of the power storage module 4 according to the present embodiment will be described.

In this method of manufacturing the power storage module 4, since the molten surface 101a of the hot plate main body 101 is covered with the cover plate 102, it is possible to prevent the resin from adhering to the molten surface 101a. Therefore, the replacement time of the hot plate main body 101 can be reduced, and the deterioration of productivity can be suppressed. Moreover, since the cover plate 102 is made of a rigid body having high thermal conductivity, it is possible to prevent the heat of the hot plate main body 101 from being blocked and to prevent the surface accuracy of the molten surface from being lowered. Therefore, the amount of melting of the joining protrusion 27 and the joining protrusion 34 is unlikely to vary. Therefore, poor bonding due to hot plate welding can be suppressed. As described above, it is possible to suppress joint failure and deterioration of productivity due to hot plate welding.

The method of manufacturing the power storage module 4 further includes a replacement step of replacing the cover plate 102. If the bonding protrusions 27 and 34 are melted by the cover plate 102 in which the resin remains on the outer surface 102a, foreign matter may be mixed into the bonding protrusions 27 and 34, resulting in poor bonding. In the method of manufacturing the power storage module 4, since the used cover plate 102 is removed and the unused cover plate 102 is attached before the welding step, it is possible to suppress the occurrence of bonding defects due to the residual resin. Since the cover plate 102 is not provided with the heater 104, the pair of temperature sensors 105, and the like, the cover plate 102 can be replaced more easily than the hot plate main body 101.

Since the cover plate 102 is formed of a metal material having a thermal conductivity equivalent to that of the hot plate main body 101 or higher than that of the hot plate main body 101, the heat transfer property and strength of the cover plate 102 are improved. Further, since the molten surface is formed as a flat surface, the variation in the melted amount of the joining protrusion 27 and the joining protrusion 34 is surely suppressed. Therefore, poor bonding due to hot plate welding can be reliably suppressed.

The cover plate 102 is fixed to the hot plate main body 101 with a plurality of bolts 103. Therefore, the heat transfer property between the hot plate main body 101 and the cover plate 102 can be enhanced through the plurality of bolts 103.

The seal member 12 of the module main body 20 is provided with a communication hole 26 communicating with the internal space V, and the case 29 of the pressure adjusting valve 23 is provided with a communication hole 33. In the welding step, the communication holes 26 and the communication holes 33 are communicated with each other. In hot plate welding between the module body 20 and the pressure regulating valve 23, for example, if the amount of melting is too large, the communication holes 26 and the communication holes 33 may be blocked by the molten resin. Further, for example, if the amount of melting is too small, the seal member 12 and the case 29 cannot be joined without a gap. In the method of manufacturing the power storage module 4, it is possible to suppress a decrease in the surface accuracy of the molten surface, so that the amount of melting of the bonding protrusion 27 and the bonding protrusion 34 is unlikely to vary. Therefore, the blockage of the communication holes 26 and 33 can be suppressed, and the seal member 12 and the case 29 can be joined without a gap.

Although the embodiments have been described in detail above, the present invention is not limited to the above embodiments.

In the above embodiment, the pressure adjusting valve 23 is welded to the module body 20 as a welded member, but the welded member may be, for example, a sealing member having no pressure adjusting function.

In the above embodiment, the power storage module 4 is a nickel-metal hydride secondary battery, but the present invention is not particularly limited to the nickel-metal hydride secondary battery, and can be applied to a lithium ion secondary battery and the like. Further, the present invention is applicable as long as the power storage module includes a module body having an electrode laminate in which a plurality of electrodes are laminated and a frame arranged so as to surround the electrode laminate, in addition to the power storage module 4. It is possible.

4 ... Power storage module, 11 ... Electrode laminate, 12 ... Seal member (second resin part), 20 ... Module body, 23 ... Pressure control valve (welded member), 25, 26 ... Communication hole (first communication hole) , 27 ... Joining protrusion, 29 ... Case (first resin part), 33 ... Communication hole (second communication hole), 34 ... Joining protrusion, 101 ... Hot plate body, 102 ... Cover plate, 102a ... Outer surface ( Melted surface), 103 ... Bolt, V ... Internal space.

Claims (6)

A method for manufacturing a power storage module having an electrode laminate in which a plurality of electrodes are laminated via a separator.
It includes a welding step of joining and integrating the electrode laminate and the module body having the first resin portion and the welded member having the second resin portion by hot plate welding.
In the welding step, a hot plate welding device including a hot plate main body in which a heat generating portion is arranged and a thin plate-shaped cover plate made of a rigid body having high thermal conductivity attached to and detachable from the hot plate main body is used. The cover plate is formed when the first resin portion and the second resin portion are brought into contact with each other on the molten surface of the plate, and the first resin portion and the second resin portion are each heated and melted by a preset amount of melting. A method for manufacturing a power storage module, in which the first resin portion and the second resin portion are separated from the molten surface, and then the first resin portion and the second resin portion are brought into pressure contact with each other. The claim further comprises a replacement step of removing the used cover plate attached to the hot plate body of the hot plate welding device and attaching the unused or after cleaning the unused cover plate before the welding step. Item 2. The method for manufacturing a power storage module according to item 1. The cover plate according to claim 1 or 2, wherein the cover plate is formed of a metal material having a thermal conductivity equivalent to or higher than that of the hot plate body, and the molten surface is formed as a flat surface. Manufacturing method of power storage module. The method for manufacturing a power storage module according to any one of claims 1 to 3, wherein the cover plate is fixed to the hot plate body by bolts. The method for manufacturing a power storage module according to any one of claims 1 to 4, wherein the welded member is a pressure adjusting valve for adjusting the pressure in an internal space provided between adjacent electrodes of the module body. .. The first resin portion is provided with a first communication hole that communicates with the internal space.
The second resin portion is provided with a second communication hole.
The fifth aspect of the present invention, wherein in the welding step, the first resin portion and the second resin portion are joined by hot plate welding so that the first communication hole and the second communication hole communicate with each other. Manufacturing method of power storage module.

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