Pressure bag for secondary battery and method of manufacturing the same

Abstract

To provide a pressure bag for a secondary battery that can ensure the bonding strength between a cover member and a bag body, and can be easily incorporated into a battery pack, etc. by suppressing deformation during manufacturing of the sheet material that constitutes the bag body of the pressure bag for a secondary battery.SOLUTION: A pressure bag for a secondary battery used when pressurizing a secondary battery suppresses deformation of a sheet material when a cover member is attached from the front and back sides of the sheet material, and ensures the bonding strength between the bag main body and the cover member by inscribing a sheet support member for fixing the sheet material along the entire length of one peripheral edge of the bag main body on one side of the bag main body where the sheet material is overlapped.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a pressure bag that applies pressure to a thin, flat secondary battery in the thickness direction. [Background technology]

[0002] In recent years, there has been a demand for small, lightweight, and highly safe secondary batteries for battery packs used in electric vehicles and hybrid vehicles. Conventional secondary batteries using liquid electrolytes require the use of aqueous solutions or organic solvents as solvents, which pose problems such as electrolyte evaporation, decomposition, leakage, and fire. Therefore, expectations are growing for so-called all-solid-state batteries, which use non-flammable solid electrolytes.

[0003] On the other hand, in all-solid-state batteries, it is necessary to increase the adhesion at the interface between the solid electrolyte and the electrodes in order to operate the battery, and by applying a certain amount of pressure to the secondary battery, the formation of crystalline precipitates is prevented and power generation efficiency is optimized. Therefore, secondary batteries are used in a pressurized environment using a pressure bag.

[0004] For example, Patent Documents 1 and 2 disclose a technology in which multiple secondary batteries are stacked at equal intervals, spacers (pressurized bags) that can be expanded by air (gas) pressure are placed between the secondary batteries, and the spacers pressurize the secondary batteries in the thickness direction. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. WO2015-141631 [Patent Document 2] Japanese Patent Application Publication No. 2019-128980 Summary of the Invention [Problem to be solved by the invention]

[0006] In the technology for pressurizing secondary batteries, a pressure bag may be used, which is a flat bag made by overlapping flexible sheets and joining their peripheries. For example, a pressure bag like a pouch bag made by overlapping laminate films is used. Such pressure bags can be made thin, which can contribute to the compactness of battery packs in which multiple secondary batteries are stacked.

[0007] However, when a pressure bag such as a pouch bag is used, the sheet-like material that constitutes the bag body of the pressure bag itself lacks rigidity, which can make it difficult to position when incorporating it into a battery pack or the like.

[0008] For this reason, methods have been considered for facilitating the fixation of the pressure bag to the battery pack by providing a cover member on the periphery of the pressure bag that has a portion for positioning when the pressure bag is incorporated into the battery pack, etc., and for supporting the battery pack, etc. In particular, providing the cover member by an insert molding or overmolding process allows molding and joining to be performed in a single process, which is preferable from the viewpoint of manufacturing efficiency.

[0009] In insert molding or overmolding, a mold for injection molding the cover member is prepared, and the part to which the cover member is to be attached, such as the end of the pressure bag, is placed in the mold, and resin is then injected into the mold. This process is called insert molding or overmolding. Through this process, the cover member is molded into the mold, and a part (e.g., the end) of the pressure bag placed in the mold is joined and integrated with the cover member.

[0010] It has been found that if the location where the cover member is provided on the bag body of a pressurized bag is only the flexible sheet material that makes up the bag body, deformation of the sheet material (twisting, torsion, bending, etc.) is likely to occur during molding. In the process of overmolding the cover member, when the flexible sheet material that makes up the bag body is placed in an injection mold and overmolded, the flexible sheet material alone cannot withstand the pressure of the resin injected into the mold, causing deformation of the sheet material and the risk that the bag body (especially the peripheral edge) will not be positioned in the desired position.

[0011] If deformation occurs in the bag main body and the peripheral edge of the bag main body is not positioned in the desired position, the relative position of the cover member and the bag main body will no longer be accurate, which will undesirably impair the strength of the bond between the cover member and the bag main body and the reliability of the bond itself.

[0012] Therefore, the object of the present invention is to efficiently provide a pressure bag for a secondary battery that suppresses excessive deformation of the bag main body during molding, particularly during molding of the cover member, ensures the bonding strength between the cover member and the bag main body, and can be easily incorporated into a battery pack, etc. [Means for solving the problem]

[0013] In the pressure bag for secondary batteries of the present invention, when constructing a thin-plate pressure bag for secondary batteries, airtight and flexible sheet materials are stacked together and the peripheral edges of both sheets are joined to form a bag main body portion that is approximately rectangular in front view, and a sheet support member having a sheet joining surface that is inscribed in the sheet material along the entire length of at least one side of the peripheral edge of the bag main body portion is inscribed in the bag main body portion.This suppresses deformation of the sheet material when molding the cover member, ensures the joining strength between the cover member and the bag main body portion, and makes it easy to incorporate into a battery pack, etc.

[0014] The present invention is a thin-plate pressure bag for a secondary battery, the pressure bag for a secondary battery including at least a bag main body, a sheet support member, and a cover member, the bag main body having a generally rectangular shape in front view formed by overlapping airtight and flexible sheet materials with their peripheral edges joined together, the sheet support member having a sheet joining surface that inscribes the sheet material along the entire length of at least one side of the peripheral edge of the bag main body, and the cover member is provided so as to sandwich the sheet material and the sheet support member inscribed in the sheet material from the outside of the bag main body and is joined to the bag main body (first invention).

[0015] In the first invention, it is preferable that the thickness of the inside of the bag body portion of the sheet support member is thinner than the thickness of the outside (second invention), and in the first invention, it is preferable that the thickness of the sheet support member at its longitudinal ends is thinner than the thickness of the center (third invention).More preferably, the sheet support member may include the components of both the second and third inventions.

[0016] Furthermore, in the first invention, it is preferable that the cross section of the cover member along its longitudinal direction is substantially square-shaped (fourth invention) or substantially square-shaped (fifth invention) so as to connect the front side to the back side of the bag body. More preferably, the cover member may include the components of both the fourth and fifth inventions.

[0017] Furthermore, in the first invention, the cover member may be provided over the entire length of at least one side of the peripheral edge of the bag body (sixth invention).

[0018] Further, there is provided a method for manufacturing a pressurized bag for a secondary battery (seventh invention) of the first to sixth inventions, characterized in that it includes a joining process for joining the sheet material that constitutes the bag main body portion, an inscribed process for inscribedly contacting the sheet material and the sheet support member in the bag main body portion on at least one side of the peripheral portion of the sheet material, and a process for joining the sheet material and the sheet support member to the bag main body portion from the front and back sides of the bag main body portion while overmolding the cover member so as to sandwich the inscribed portions of the sheet material and the sheet support member. [Effects of the Invention]

[0019] According to the secondary battery pressure bags (first to sixth aspects) of the present invention, a secondary battery pressure bag used to pressurize a secondary battery incorporated in a battery pack or the like has a sheet support member inscribed in the sheet material along the entire length of at least one edge of the bag body. This prevents deformation of the sheet material constituting the bag body when a cover member, which serves as an attachment to the battery pack, is attached to the pressure bag, improving bonding strength stability and reliability, and enabling easy incorporation into the battery pack. Furthermore, a secondary battery pressure bag can be obtained that can stably apply an appropriate amount of pressure to the secondary battery. Furthermore, according to the method for manufacturing a secondary battery pressure bag (seventh aspect) of the present invention, a secondary battery pressure bag with stable bonding strength and reliability between the components can be efficiently manufactured.

[0020] According to the manufacturing method for a pressure bag for a secondary battery of the present invention (7th invention), when the cover member is molded by overmolding, deformation of the sheet material is suppressed, the bonding strength between the cover member and the bag main body is ensured, and a pressure bag for a secondary battery that is easy to incorporate into a battery pack, etc. can be efficiently obtained. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a schematic diagram showing the structure of a battery pack incorporating a pressure bag for a secondary battery according to a first embodiment of the present invention. [Figure 2]1 is a schematic view of a pressure bag for a secondary battery according to a first embodiment of the present invention. [Figure 3] 3 is a schematic diagram illustrating an example of a flow of a manufacturing process of the pressure bag for a secondary battery according to the first embodiment of the present invention. FIG. [Figure 4] 1 is a schematic diagram showing an example of a seat support member used in practicing the present invention; [Figure 5] 1 is a schematic diagram showing an example of a seat support member with a lead-in portion used in implementing the present invention; [Figure 6] 5A to 5C are schematic diagrams illustrating an example of the flow of a molding step of a cover member in the manufacturing process of the bag body according to the first embodiment of the present invention. [Figure 7] FIG. 4 is a schematic view illustrating a modified example of the pressurizing bag for a secondary battery according to the first embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0022] Hereinafter, with reference to the drawings, an embodiment of the invention will be described using as an example a pressurized bag 1 for a secondary battery that is stacked together with secondary batteries in a battery pack, particularly a battery pack 9 used in electric vehicles or hybrid vehicles. The invention is not limited to the individual embodiments shown below, and can be implemented by modifying the form. The invention can be implemented with either a secondary battery 5 that uses a liquid electrolyte or an all-solid-state battery that uses a solid electrolyte. An example of the secondary battery 5 is a lithium-ion battery.

[0023] FIG. 1 schematically shows the structure of a battery pack 9 incorporating a pressurized bag 1 for a secondary battery according to one embodiment of the present invention. The secondary battery 5 is flat, and a plurality of flat-shaped secondary batteries 5 are stacked to form the battery pack 9. The secondary batteries 5 are electrically connected to each other by bus bars (not shown) or the like, and function as the battery pack 9. The secondary battery 5 is not particularly limited, but is typically a lithium-ion battery or an all-solid-state battery.

[0024] The pressurizing bag 1 for a secondary battery according to this embodiment is disposed in the gaps between stacked secondary batteries 5, 5, and is provided with a certain thickness within the assembled battery 9 in which the secondary batteries are disposed.

[0025] In addition, in the battery pack 9, the secondary batteries 5 may be sandwiched between the pressure bags 1 for secondary batteries and pressurized on both sides by the pressure bags 1 for secondary batteries, or the secondary batteries 5 may be arranged at both ends so that only one end face is in contact with the pressure bag 1 for secondary batteries and the other end face is in contact with the end plate 6, so that the secondary batteries 5 are pressurized from both sides.

[0026] FIG. 2 shows an outline of a pressurizing bag 1 for a secondary battery according to one embodiment of the present invention. The pressurizing bag 1 for a secondary battery can be broadly divided into a bag main body 10, a sheet support member 2, and a cover member 3. Although not required, a pressure measurement terminal may be provided on the surface of the bag main body 10. This allows the pressure applied from the pressurizing bag 1 to the secondary batteries 5, 5 to be measured in real time, making it possible to instantly identify any malfunctions that may occur. Although not required, the bag main body 10, the cover member 3, or the sheet support member 2 may be provided with an introduction port for introducing contents into the bag main body 10. This allows the pressure applied from the pressurizing bag 1 to the secondary batteries 5, 5 to be adjusted appropriately.

[0027] Furthermore, although not essential, a plurality of sheet support members 2 and cover members 3 may be used for one pressurized bag for a secondary battery. In this embodiment, one sheet support member and one cover member are provided for the bag main body 10.

[0028] The bag body 10 only needs to be designed so that its size in both the short and long sides is approximately the same as that of the secondary battery 5 to be pressurized, and the thickness of the bag body 10 increases or decreases depending on the loading and unloading of the contents. As a result, it becomes possible to apply the necessary pressure in the thickness direction of the secondary battery 5 while minimizing uneven pressure applied to the secondary battery 5. The size of the bag body 10 may be smaller than that of the secondary battery 5.

[0029] The bag body 10 has a generally rectangular shape when viewed from the front, and is configured in the shape of a bag by overlapping sheet materials (11, 12) and joining the overlapping sheet materials at their peripheral edges.

[0030] The sheet support member 2 is inscribed in the bag main body 10 via a sheet joining surface 21 that is inscribed in the sheet material along the entire length of at least one side of the periphery of the bag main body 10. That is, the sheet support member 2 is arranged so as to be sandwiched between the sheet materials (11, 12). In the portion where the sheet support member 2 is sandwiched between the sheet materials (11, 12), the sheet materials (11, 12) and the sheet joining surface 21 of the sheet support member 2 are joined. In this embodiment, the sheet support member 2 is provided along the entire length of one side of the bag main body 10. The sheet support member 2 may also be provided along the entire lengths of multiple sides (for example, two opposing sides) of the bag main body 10.

[0031] The cover member 3 is provided so as to sandwich the sheet materials (11, 12) and the sheet support member 2 inscribed in the sheet materials (11, 12) from the front and back sides of the bag main body 10. In other words, the sheet support member 2 is disposed on the side on which the cover member 3 is provided. Although not essential, the cover member 3 may be provided over the entire length of the side on which the sheet support member 2 is provided.

[0032] The cover member 3 serves as a positioning member when the pressurized bag for secondary batteries 1 is incorporated into the battery pack 9, and is provided on at least one side of the peripheral edge of the bag main body 10, making it easy to position the bag when incorporating it into the battery pack 9.

[0033] On the side where the cover member 3 is provided, the sheet support member 2 is inscribed between the sheet materials (11, 12) over the entire length of that side, so that deformation of the sheet materials (11, 12) can be suppressed when the cover member 3 is provided.

[0034] FIG. 3 shows an outline of a manufacturing method for the pressurized bag 1 for a secondary battery. The sheet materials (11, 12) constituting the bag body 10 are not particularly limited as long as they are airtight and flexible enough to be used in the pressurized bag 1 for a secondary battery. Any sheet material that can withstand the pressure of the bag itself, is airtight or liquid-tight enough to prevent gas or liquid from passing through even when filled with gas or liquid contents, and has appropriate stretchability and flexibility can be used. For example, the sheet may be a single-layer sheet or a multi-layer sheet. Single-layer sheets include metal sheets such as aluminum foil, resin sheets such as polypropylene (PP) and polyethylene terephthalate (PET), and even rubber or thermoplastic elastomer sheets. Multi-layer sheets include sheets obtained by laminating and integrating the same single-layer sheets. Furthermore, composite sheets with vapor-deposited metals, silica, or the like can also be used. Reinforcing fibers may be mixed into the sheet material to improve its physical properties. In this embodiment, a multi-layer sheet in which aluminum foil is sandwiched between PET resin sheets can be used.

[0035] Depending on the environment in which the secondary battery 5 is used, the temperature change of the secondary battery 5 can reach approximately 100°C. Therefore, it is preferable that the sheet material constituting the bag main body 10 is resistant to deformation, alteration, and deterioration due to the temperature change, and it is preferable that it is made of metal foil or has metal vapor deposition.

[0036] The bag body 10 is formed by joining the front sheet material 11 and the back sheet material 12 together so that the bag is closed all around. Various methods can be used for this joining, depending on the materials of the two sheet materials (11, 12). The joining may be by adhesion using an adhesive, or by cross-linking adhesion utilizing a cross-linking reaction of rubber or the like. Furthermore, when the sheet materials (11, 12) are formed by laminating a thermoplastic resin on one side of both sheet materials (11, 12), the joining may be by welding. Examples of welding methods include so-called hot plate welding, ultrasonic welding, high-frequency welding, laser welding, and infrared welding.

[0037] In manufacturing the bag main body 10, for example, in order to inscribe the sheet support member 2 in a later process, first, as shown in Figure 3(b), the sheet material may be joined at a joint except for the edge where the sheet support member 2 will be inscribed (the joint is designated as AA1 and is shown hatched in Figure 3(b)), and the bag shape may be formed. Thereafter, as shown in Figure 3(c), the sheet support member 2 may be placed between the sheet materials (11, 12), and the sheet support member 2 and the sheet materials (11, 12) may be joined (the joint joined in the process of Figure 3(d) is designated as AA2 and is shown hatched in Figure 3(d)). While Figure 3 shows an example in which one sheet support member 2 is provided, multiple sheet support members 2 may be used per bag main body 10 (for example, one on each of the opposing short sides of the bag main body 10, which is generally rectangular in front view).

[0038] FIG. 4 shows an embodiment of the sheet support member 2, and FIGS. 4(a) to 4(e) show examples of the shape of the sheet support member 2. In each figure, the left-hand side is a perspective view, and the right-hand side is a front view in the short direction. The longitudinal direction of each of these sheet support members 2 has a length that is approximately the same as one side of the peripheral edge of the bag main body portion 10. In addition, in the side views of FIGS. 4(a) to 4(e), the upper side of the figure corresponds to the outside of the bag main body portion 10, and the lower side corresponds to the inside of the bag main body portion 10. In addition, the sheet support member 2 may be provided with holes, notches, etc. as appropriate.

[0039] These sheet support members 2 are inserted between the sheet materials (11, 12) that form the front and back surfaces of the bag main body 10, and are joined to the sheet materials (11, 12) at the peripheral edges of the sheet materials (11, 12) at the sheet joining surfaces 21 of the sheet support members 2. Various methods can be used for this joining, depending on the materials of the sheet materials (11, 12) and the sheet support member 2. The joining may be by adhesion using an adhesive, or by cross-linking adhesion using the cross-linking effect of rubber or the like. Furthermore, if the sheet materials (11, 12) are made by laminating a thermoplastic resin on one side of both sheet materials, the joining may be by welding. Examples of welding methods include so-called hot plate welding, ultrasonic welding, high-frequency welding, laser welding, and infrared welding.

[0040] Furthermore, if the sheet support member 2 has a generally rectangular parallelepiped shape as shown in FIG. 4(a), sufficient bonding strength with the sheet materials (11, 12) can be obtained when the sheet support member 2 is inserted between the sheet materials (11, 12). Preferably, as shown in FIG. 4(b) or (c), the thickness of the sheet support member 2 at the portion where it is bonded to the interior of the bag main body 10 (inside the bag main body 10) may be thinner than at the peripheral edge of the bag main body 10 (outside the bag main body 10). That is, as shown in FIG. 4(b), the cross section in a plane perpendicular to the longitudinal direction (longitudinal cross section in the short direction) may have a constant thickness up to a certain point so as to form a tower shape with a pointed tip, and the thickness may become thinner at a certain point. Alternatively, as shown in FIG. 4(c), the thickness may change continuously so as to form a generally equilateral or isosceles triangle.

[0041] 4(d) or 4(e), the thickness of the sheet support member 2 at its longitudinal ends may be thinner than the thickness of the central portion. That is, as shown in Fig. 4(d), the thickness may be thinner at a certain position in the longitudinal direction of the sheet support member 2, or as shown in Fig. 4(e), the thickness may be greatest at the longitudinal center of the sheet support member 2 and change continuously toward the ends.

[0042] 4(b) and 4(c) and both of the tapered shapes shown in Fig. 4(d) and 4(e) may be used. In either case, the sheet support member 2 has a sheet joining surface 21 having substantially the same length as one side of the bag body portion 10 that is inscribed therein.

[0043] Furthermore, although not shown, the seat support member 2 may be formed so that part or all of its outer periphery describes an arc, so that the cross-sectional shape in a plane including the longitudinal and lateral directions in Figure 4 is approximately elliptical or oblong.

[0044] By making the thickness of the end portion of the sheet support member 2 thinner than that of the central portion, it becomes easier to join the sheet support member 2 and the sheet material (11, 12), and it becomes possible to reduce the risk of the contents leaking.

[0045] As shown in Figures 5(a) to (d), the sheet support member 2 may be provided with an introduction section 4 that is joined to a tube from a pump or the like (not shown). For example, as shown in Figure 5(a) or (b), the introduction section 4 may be formed in a hollow tubular shape with a convex member 41 (e.g., a nipple), and may be provided on the upper surface of the sheet support member 2 so as to protrude, or on both the upper and lower surfaces. Even in this case, the contents discharged from the pump or the like can be introduced into the bag main body 10. The length of the introduction section 4 is sufficient to at least be long enough to be airtightly connected to the pump and the tube piping, and is preferably shorter than the bag main body 10.

[0046] As another form of the introduction part 4, the introduction part 4 may be a through-hole 42 that penetrates the inside and outside of the sheet support member 2, as shown in Fig. 5(c). By connecting a tube from a pump or the like to the through-hole, it becomes possible to introduce the contents into the bag main body 10 and apply an appropriate pressure to the secondary battery.

[0047] As another embodiment of the introduction section 4, as shown in Figure 5(d), the introduction section 4 may be a hollow straw-shaped member 43 provided circumscribing the side surface of one longitudinal end of the sheet support member 2, or may be provided as an integral member with the sheet support member 2 via a connecting member (not shown) extending from the side surface of the end. In this case, the outer peripheral surface of the straw-shaped member 43 also functions as the sheet joining surface 21 of the sheet support member 2, making it possible to ensure the joining strength between the sheet material (11, 12) constituting the bag main body 10 and the sheet support member 2. The straw-shaped members 43 may be provided at both longitudinal ends of the sheet support member 2.

[0048] In the pressurized bag 1 for a secondary battery according to this embodiment, the sheet support member 2 is preferably made of a hard resin such as polypropylene (PP) or acrylonitrile-butadiene-styrene copolymer resin (ABS resin), and more preferably, a fiber-based reinforcing material such as glass fiber is mixed in to suppress dimensional changes due to temperature changes in the secondary battery.

[0049] The sheet support member 2 only needs to have a sheet joining surface 21 having a length and width that allows the sheet support member 2 to be inscribed with the sheet material (11, 12) along the entire length of at least one side of the peripheral edge of the bag main body 10. By providing the sheet support member 2 so that it has the sheet joining surface 21 along the entire length of at least one side of the peripheral edge of the bag main body 10, the sheet material (11, 12) that constitutes the bag main body 10 is firmly joined to the sheet support member 2. Therefore, when a cover member 3 (described later) is provided, the sheet support member 2 reinforces the sheet material (11, 12), suppressing deformation of the sheet material (11, 12), and facilitating the molding of the cover member 3.

[0050] The cover member 3 can be molded by various molding methods so as to sandwich the sheet materials (11, 12) and the sheet support member 2 inscribed in the sheet materials (11, 12) from the outside of the bag body 10. From the viewpoint of manufacturing efficiency, it is preferable to provide it by insert molding or overmolding, and it is particularly preferable to provide it by overmolding.

[0051] FIG. 6 shows a schematic example of the overmolding process for the cover member 3 according to the present invention. The process proceeds in the order of (a) to (e) in FIG. 6. Each process can be performed using known techniques. Specifically, molds (D1, D2) for injection molding the cover member 3 are prepared, and the bag body 10 and sheet support member 2 are prepared as shown in FIGS. 3(a) to (e). Then, (a) the sheet materials (11, 12) of the bag body 10 and the sheet support member 2 inscribed in the sheet materials (11, 12) are placed in the molds (D1, D2). (b) After the peripheral edge of the bag body 10 and the sheet support member are placed in the predetermined positions, the molds (D1, D2) are closed to create a cavity (CV) for forming the cover member 3. (c) Resin for the cover member 3 is injected into the cavity (CV) of the molds (D1, D2). (d) Resin is filled into the cavity (CV), the shape is maintained for a predetermined time, and the filled resin is hardened to form the cover member 3, while being integrally bonded to the peripheral edge of the bag body portion 10. (e) The molding dies (D1, D2) are opened, and the product is removed.

[0052] In terms of manufacturing efficiency, it is preferable to provide the cover member 3 by an overmolding process. In particular, by using a molding die (D1, D2) corresponding to the installation location of the sheet support member 2, it is possible to efficiently mold and produce a pressurized bag for a secondary battery. In this case, the sheet support member 2 is sandwiched and joined to the sheet material (11, 12) constituting the bag main body 10 along the entire length of at least one side of the periphery of the bag main body 10 where the cover member 3 is provided. This prevents unnecessary deformation (twisting, torsion, bending, etc.) of the sheet material (11, 12) in the overmolding process, ensures the bonding strength between the cover member 3 and the bag main body 10, and makes it possible to efficiently provide a pressurized bag for a secondary battery 1 that can be easily incorporated into an assembled battery 9, etc.

[0053] In the pressurized bag 1 for a secondary battery in this embodiment, the cover member 3 is preferably made of the same material as the sheet support member 2, and is preferably formed by overmolding after the sheet support member 2 is inscribed in the bag main body 10. Furthermore, the cover member 3 is preferably provided by molding it so as to cover the entire length of one side of the peripheral edge of the bag main body 10 in which the sheet support member 2 is inscribed, as in the above example.

[0054] The cover member 3 sandwiches the sheet support member 2 and the bag body 10 from the front and back sides of the bag body 10 and is joined to the bag body 10. The cover member 3 is thicker than the bag body 10. As shown in FIG. 1 , contacting the cover members 3 with each other can also serve as a support when ensuring clearance (equal to or greater than the thickness of the battery cells) between the bag bodies 10. Furthermore, the cover member 3, which includes an attachment portion and a positioning portion, is joined to the bag body 10, making it possible to easily incorporate the pressurized bag 1 for a secondary battery into an assembled battery 9 or the like. Furthermore, since the cover member 3 is joined to the periphery of the bag body 10, the cover member 3 itself functions as a reinforcing member for the bag body 10. This prevents one side of the bag body 10 from deforming into a concave arc due to expansion of the bag body 10 as the internal pressure of the bag body 10 increases, thereby preventing uneven pressure on the secondary battery 5 and leakage of the contents.

[0055] Furthermore, as described in the pressurization bag 1 for a secondary battery according to the above embodiment (FIG. 2, sectX-X), the cover member 3 may have a substantially rectangular cross section along its longitudinal direction so as to connect the front side to the back side of the bag body 10. In this case, the inner portion of the rectangular short side at the periphery of the bag body 10 to which the sheet support member 2 is joined is tightly joined to the end face portions of the sheet support member 2 and the bag body 10. This prevents peeling of the joint between the inner contact portion of the sheet material (11, 12) of the bag body 10 and the sheet support member 2 as the pressure applied to the pressurization bag 1 for a secondary battery increases. Even if the joint does peel, the tightly joined cover member 3 prevents leakage of the contents. In addition, the cover member 3 also serves as a pressing member for the sheet material (11, 12) at the long side of the L-shaped periphery of the bag main body 10 to prevent the joint between the sheet material (11, 12) of the bag main body 10 and the sheet support member 2 from peeling off, making the seal more reliable and thus preventing leakage of the contents.

[0056] 6, the cover member 3 may have a substantially U-shaped cross section in a plane perpendicular to the longitudinal direction (longitudinal cross section in the short direction) so as to connect the front side to the back side of the bag body 10. In this case, the inner part of the U-shape at the periphery of the bag body 10 to which the sheet support member 2 is joined is tightly joined to the end of the sheet support member 2 and the upper surface of the end of the bag body 10. This prevents peeling of the joint at the inner contact part between the sheet material (11, 12) of the bag body 10 and the sheet support member 2 as the pressure on the pressurized bag 1 for a secondary battery increases. Even if the joint does peel, leakage of the contents can be prevented due to the effect of the cover member 3 being tightly joined.

[0057] Furthermore, although not essential, the cover member 3 may be molded into a square or U-shape so as to cover both the longitudinal and lateral end faces of the bag body 10. Covering both the longitudinal and lateral end faces with the cover member 3 can provide the effect of improving the airtightness of the pressurizable bag 1 for secondary batteries and further preventing peeling of the sheet of the bag body 10. In this case, the cover member 3 can be provided more efficiently by overmolding, but the molding method is not particularly limited.

[0058] As shown in Fig. 7, the sheet support member 2 of the present invention may be provided so as to protrude from the bag main body portion 10 and may be joined to the bag main body portion 10. The sheet support member 2 has a protruding portion, and the sheet support member 2 has a portion that is not covered by the sheet material (11, 12) when viewed from the direction perpendicular to the surface of the bag main body portion 10. In this case, the protruding portion can be used to more reliably position the sheet support member 2 and the peripheral edge portion of the bag main body portion 10 inside the molding die when overmolding the cover member 3, and the cover member 3 can be more accurately integrated with the bag main body portion 10.

[0059] In the present invention, the content introduced into the bag body 10 may be liquid or gas. However, since it is expected that the temperature of the secondary battery 5 may change by approximately 100°C depending on the state of use, the content is preferably liquid, and more preferably antifreeze containing glycerin, ethylene glycol, propylene glycol, or the like as its main component.

[0060] When the sheet support member 2 is provided on each of a plurality of different peripheral portions (sides) of the bag main body 10, a cover member 3 may be provided on each peripheral portion. In this case, it is possible to further obtain effects such as concave deformation of the bag main body 10 on each side, displacement of the introduction portion 4, and suppression of leakage of the contents. [Industrial Applicability]

[0061] The pressure bag 1 for secondary batteries of the above embodiment can be used as a pressure bag for secondary batteries 5, and the method for manufacturing the pressure bag 1 for secondary batteries of the above embodiment can efficiently manufacture a highly reliable pressure bag 1 for secondary batteries, making it highly industrially useful. [Explanation of symbols]

[0062] 1. Pressure bag for secondary batteries 10 Bag body 11 Front sheet material 12 Back sheet material 2 Seat support member 21 Sheet joint surface 3 Cover material 4 Introduction 41 Convex member 42 Through hole 43 Straw-shaped member 5 Secondary battery 6 End Plate AA1, AA2 sheet material joint CV cavity D1, D2 molding dies 9 Battery pack

Claims

1. A thin-plate pressurized bag for a secondary battery, The pressurized bag for a secondary battery includes at least a bag body, a sheet support member, and a cover member, The bag body has a generally rectangular shape in front view, and is formed by overlapping airtight and flexible sheet materials and joining the peripheral edges of both sheet materials together. the sheet support member has a sheet joining surface that is inscribed with the sheet material over the entire length of at least one side of the peripheral edge of the bag main body, The cover member sandwiches the sheet material and the sheet support member inscribed in the sheet material from the front and back sides of the bag main body portion, and is joined to the bag main body portion. Pressure bag for secondary batteries.

2. The seat support member is The inner thickness of the bag body is thinner than the outer thickness. The pressure bag for a secondary battery according to claim 1 .

3. The seat support member is The thickness of the end portion in the longitudinal direction is thinner than the thickness of the central portion. The pressure bag for a secondary battery according to claim 1 .

4. The cover member is The cross section of the cover member along the longitudinal direction is approximately square-shaped so as to connect the front side to the back side of the bag body portion. The pressure bag for a secondary battery according to claim 1 .

5. The cover member is The cross section of the cover member along the short side is substantially U-shaped so as to connect the front side to the back side of the bag body. The pressure bag for a secondary battery according to claim 1 .

6. The cover member is The protective film is provided over the entire length of at least one side of the peripheral edge of the bag body portion. The pressure bag for a secondary battery according to claim 1 .

7. A method for manufacturing a pressure bag for a secondary battery according to any one of claims 1 to 6, comprising the steps of: a joining step of joining the sheet material that constitutes the bag main body portion; an inscribed contact step of inscribedly contacting the sheet material and the sheet support member in the bag main body portion along at least the entire length of the one side of the peripheral edge portion of the sheet material; and joining the cover member to the bag body portion by overmolding from the front and back sides of the bag body portion so as to sandwich the inner contact portion between the sheet material and the sheet support member. A method for manufacturing the pressure bag for a secondary battery according to any one of claims 1 to 6.

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