Bipolar secondary battery

Abstract

A bipolar secondary battery according to an embodiment of the present invention may comprise: a bipolar stack cell having a plurality of bipolar unit cells and electrolyte membranes, wherein the bipolar unit cells are stacked along a stacking direction, each of the bipolar unit cells has a positive electrode layer formed on one surface of an electrode plate thereof and a negative electrode layer formed on the other surface thereof, and each of the electrolyte membranes is disposed between adjacent bipolar unit cells; a first sealing part surrounding and sealing the bipolar stack cell; and a side frame in which a second sealing part that is spaced apart from the first sealing part, surrounds the bipolar stack cell, and seals the bipolar stack cell from the outside is arranged.

Description

bipolar secondary battery

[0001] The present invention relates to a bipolar secondary battery. The present application claims the benefit of priority based on Korean Patent Application No. 2024-0185052 filed December 12, 2024 and Korean Patent Application No. 2025-0137405 filed September 23, 2025, and all contents disclosed in the documents of said Korean patent applications are incorporated herein as part of the specification.

[0002] Unlike primary batteries, secondary batteries can be charged and discharged, making them applicable to various fields such as digital cameras, mobile phones, laptops, hybrid cars, electric vehicles, and aircraft. Nickel-cadmium batteries, nickel-metal hydride batteries, and nickel-hydrogen batteries are used as secondary batteries, and recently, lithium-ion batteries have been particularly popular.

[0003] In particular, bipolar rechargeable batteries feature a structure in which multiple unit cells are stacked and connected in series, enabling the efficient realization of high voltage and high energy density. Compared to conventional single-cell based batteries, bipolar rechargeable batteries offer higher space efficiency and enable weight reduction, attracting attention in fields requiring high output and large capacity power, such as electric vehicles, energy storage systems (ESS), and aircraft. However, these bipolar rechargeable batteries possess structural complexity, and sealing and stability between the stacked cells present significant technical challenges. Specifically, since electrolyte leakage or the ingress of external moisture and foreign substances can lead to battery performance degradation and safety issues, there is a need for advanced sealing structures.

[0004] The aforementioned background technology is one that the inventor possessed or acquired in the process of deriving the contents of the disclosure of the present application, and it cannot be considered as prior art disclosed to the general public prior to the filing of this application.

[0005] Embodiments of the present invention have been devised in consideration of the aforementioned problems, and the objective of the present invention is to provide a bipolar secondary battery having a double sealing structure capable of preventing electrolyte leakage and external moisture penetration.

[0006] A bipolar secondary battery according to an embodiment of the present invention may include: a bipolar stack cell having a plurality of bipolar unit cells that are stacked together along a stacking direction, wherein a positive electrode layer is formed on one side of an electrode plate and a negative electrode layer is formed on the other side, and an electrolyte membrane disposed between adjacent bipolar unit cells; a first sealing part that surrounds and seals the bipolar stack cell; and a side frame having a second sealing part that surrounds the bipolar stack cell and seals the bipolar stack cell from the outside, spaced apart from the first sealing part.

[0007] A pair of cover plates that overlap the bipolar stack cell in the stacking direction may be further included to transfer power from the bipolar stack cell to the outside.

[0008] The second sealing portion may be formed between the side frame and the cover plate.

[0009] The second sealing portion may be formed along the edge of the cover plate.

[0010] The stacking direction height of the first sealing part may be higher than the stacking direction height of the bipolar stack cell.

[0011] The first sealing portion protrudes from the bipolar stack cell by a predetermined height in the stacking direction, and the protruding first sealing portion can be sealed with the inner surface of the pair of cover plates.

[0012] The above pair of cover plates includes a first cover plate that overlaps the top of the bipolar stack cell and a second cover plate that overlaps the bottom of the bipolar stack cell, and the first cover plate and the second cover plate may be spaced apart from each other with the side frame in between.

[0013] The above side frame may include a frame body extending between the first cover plate and the second cover plate to support the cover plate; and an insulating portion provided on the frame body to insulate the first cover plate and the second cover plate.

[0014] The above insulating portion may be provided in a form that protrudes from the frame body between the spaced-apart first cover plate and the second cover plate.

[0015] The second sealing portion may include a plate sealing portion formed at the end of the frame body in the stacking direction to be sealed with the cover plate; and a side sealing portion that overlaps the insulating portion to seal the spaced-apart first cover plate and the second cover plate.

[0016] The end of the electrode plate can be inserted horizontally into and supported in the first sealing portion.

[0017] The first sealing portion may include a plurality of layers made of different materials.

[0018] A bipolar secondary battery according to an embodiment of the present invention is provided with a double sealing structure to effectively prevent electrolyte leakage and the intrusion of external foreign matter, thereby significantly improving the stability of the secondary battery.

[0019] The effects according to the embodiments are not limited to those exemplified above, and various other additional effects predictable from the specification and drawings may also be achieved.

[0020] FIG. 1 is a schematic diagram showing the structure of a bipolar unit cell of a bipolar secondary battery according to one embodiment of the present invention.

[0021] FIG. 2 is a schematic diagram showing the structure of a bipolar stack cell of a bipolar secondary battery according to one embodiment of the present invention.

[0022] FIG. 3 is a schematic diagram showing the structure of a bipolar stack cell and a first sealing part of a bipolar secondary battery according to one embodiment of the present invention.

[0023] FIG. 4 shows a structural diagram of a bipolar secondary battery according to one embodiment of the present invention.

[0024] FIG. 5 is a schematic perspective view showing the combined form of a cover plate and a side frame of a bipolar secondary battery according to one embodiment of the present invention.

[0025] FIG. 6 is a plan view showing the shape of a side frame of a bipolar secondary battery according to one embodiment of the present invention.

[0026] FIG. 7 is a drawing showing the sealing structure of a second sealing portion of a bipolar secondary battery according to one embodiment of the present invention.

[0027] FIG. 8 is a diagram showing the structure of a bipolar secondary battery according to another embodiment of the present invention.

[0028] FIG. 9 is a schematic diagram showing the process of forming a first sealing portion of a bipolar secondary battery according to one embodiment of the present invention.

[0029] FIG. 10 is a schematic diagram showing the shape of a first sealing portion of a bipolar secondary battery according to one embodiment of the present invention.

[0030] FIG. 11 is a schematic diagram showing the process of forming a first sealing portion of a bipolar secondary battery according to another embodiment of the present invention.

[0031] FIG. 12 is a schematic diagram showing the shape of a first sealing portion of a bipolar secondary battery according to another embodiment of the present invention.

[0032] Hereinafter, embodiments are described in detail with reference to the attached drawings. The following description is one of several aspects of the embodiments, and the description below forms part of the detailed description of the embodiments. In describing one embodiment, specific descriptions regarding known functions or configurations are omitted to clarify the gist of the invention.

[0033] Terms and words used in this specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings, but should be interpreted in a meaning and concept consistent with the technical spirit of the invention, based on the principle that the inventor may appropriately define the concept of the terms to best describe his invention. Accordingly, the embodiments described in this specification and the configurations illustrated in the drawings are merely the most preferred embodiments of the invention and do not represent all aspects of the technical spirit of the invention; therefore, it should be understood that various equivalents and modifications that can replace them may exist at the time of filing this application.

[0034] Identical reference numbers or symbols in each drawing attached to this specification represent parts or components that perform substantially the same function. For convenience of explanation and understanding, the same reference numbers or symbols may be used to describe different embodiments. That is, even if components having the same reference number are depicted in multiple drawings, the multiple drawings do not all represent a single embodiment.

[0035] In the following description, singular expressions include plural expressions unless the context clearly indicates otherwise. Terms such as "comprising" or "constituting" are intended to specify the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0036] In addition, it should be noted in advance that expressions such as upper side, top, lower side, bottom, side, front, and rear in the following description are based on the direction depicted in the drawings, and may be expressed differently if the direction of the object changes.

[0037] In addition, terms such as first, second, A, B, (a), (b), etc., may be used when describing the components of the embodiments. These terms are intended merely to distinguish the components from other components, and the nature, order, or sequence of the components is not limited by these terms. Where it is stated that a component is "connected," "combined," or "connected" to another component, it should be understood that while the component may be directly connected or connected to the other component, another component may also be "connected," "combined," or "connected" between each component.

[0038] Components included in any one embodiment and components having common functions shall be described using the same names in other embodiments. Unless otherwise stated, the description in any one embodiment may also apply to other embodiments, and specific descriptions shall be omitted to the extent of overlap.

[0039] FIG. 1 is a schematic diagram showing the structure of a bipolar unit cell (10) of a bipolar secondary battery according to one embodiment of the present invention. FIG. 2 is a schematic diagram showing the structure of a bipolar stack cell (11) of a bipolar secondary battery according to one embodiment of the present invention.

[0040] Referring to FIGS. 1 and FIGS. 2, a bipolar secondary battery according to one embodiment of the present invention may include a plurality of bipolar unit cells (10).

[0041] A bipolar unit cell may be provided by forming an anode layer (103) on one side of an electrode plate (101) and a cathode layer (102) on the other side. The electrode plate (101) may be provided with a conductive material to physically separate the cathode and the anode and to form an electrical connection between the anode and the cathode. The electrode plate (101) may be formed using materials such as aluminum (Al), copper (Cu), stainless steel (SUS), or a composite material formed by bonding aluminum and copper, such as Al / Cu-Clad, and may be formed including a porous structure or a mesh structure as needed. The electrode plate (101) may be provided in the form of a rectangular plate having a predetermined length and width. The cathode layer (102) is formed on one side of the electrode plate (101), and electrons may be emitted as an oxidation reaction occurs during the discharge process of the secondary battery. The negative electrode layer may be formed using materials such as graphite, silicon (Si), or lithium (Li), but is not limited thereto. The positive electrode layer (103) is formed on the other side of the electrode plate (101) and can accept electrons through a reduction reaction during the discharge process of the secondary battery. The positive electrode layer may be formed using materials such as lithium metal oxides like lithium cobalt oxide (LiCoO2), lithium nickel manganese cobalt oxide (NMC), or lithium iron phosphate (LFP). Electrons emitted from one negative electrode layer (102) in each bipolar unit cell (10) can be moved to the positive electrode layer (103) through the conductive electrode plate (101).

[0042] A bipolar stack cell (11) of a bipolar secondary battery according to one embodiment of the present invention may be formed by stacking a plurality of bipolar unit cells (10) and an electrolyte film (12).

[0043] A plurality of bipolar unit cells (10) may be stacked along one direction. The stacking direction of the plurality of bipolar unit cells (10) may be perpendicular to the electrode plate (101). The stacking direction of the plurality of bipolar unit cells (10) may be, for example, a vertical direction. An electrolyte membrane (12) may be disposed between adjacent bipolar unit cells (10). The electrolyte membrane (12) is disposed between adjacent bipolar unit cells (10) to enable ion conduction and to block electron flow, thereby preventing a short circuit. This stacked structure of the plurality of bipolar unit cells (10) and the electrolyte membrane (12) can form an electrical series structure. In other words, each bipolar unit cell (10) performs an individual electrochemical reaction, and the entire stacked bipolar stack cell (11) can provide high voltage and high density power in a form where a plurality of bipolar unit cells (10) are connected in electrical series. The electrolyte membrane (12) may be formed as a solid with a predetermined rigidity or as a gel in a semi-solid state with fluidity, but is not limited thereto and can be provided in various forms. For example, it may be provided in a form where the electrolyte is impregnated into the separator and then cured to be used as a gel type, or where the electrolyte is impregnated into the electrode and then cured so that the separator is used to separate the positive and negative electrodes. When the electrolyte membrane (12) is provided in a gel form, the possibility of leakage is reduced compared to the existing liquid electrolyte, while structural stability can be improved.

[0044] FIG. 3 is a schematic diagram showing the structure of a bipolar stack cell (11) and a first sealing part (21) of a bipolar secondary battery according to one embodiment of the present invention.

[0045] Referring to FIG. 3, a bipolar secondary battery according to one embodiment of the present invention may include a first sealing portion (21).

[0046] The first sealing portion (21) can surround and seal the bipolar stack cell (11). The first sealing portion (21) can be formed along the outer edge of the bipolar stack cell (11). The first sealing portion (21) primarily seals the bipolar stack cell (11) from the outside and can protect the bipolar stack cell (11) from the ingress of external moisture or foreign matter. Additionally, the first sealing portion (21) can be provided to prevent leakage of the electrolyte membrane (12). As described above, the electrolyte membrane (12) can be provided in the form of a gel having a certain fluidity, and in this case, leakage of the electrolyte membrane (12) can be prevented due to the sealing structure of the first sealing portion (21). The first sealing portion (21) can fix and support the bipolar stack cell (11), which has a structure in which a plurality of bipolar unit cells (10) and an electrolyte membrane (12) are stacked. The first sealing portion (21) is formed to have a predetermined thickness in a horizontal direction perpendicular to the stacking direction of the bipolar stack cell (11), and an electrode plate (101) can be inserted and fixed in the first sealing portion (21). Each bipolar unit cell (10) of the bipolar stack cell (11) can be prevented from deviating or misaligning in the horizontal direction due to the support structure of the first sealing portion (21).

[0047] A bipolar stack cell (11) that is sealed and surrounded by a first sealing portion (21) can be arranged so that electrode plates (101) are positioned at both ends of the stacking direction. The electrode plates (101) positioned at both ends of the stacking direction of the bipolar stack cell (11) can be electrically connected to a cover plate (40) to be described later, and the electrode plate (101) positioned at one end of the stacking direction and the electrode plate (101) positioned at the other end of the stacking direction can have different electrical polarities due to the anode / cathode layers that are in contact with each other.

[0048] The stacking direction height of the first sealing part (21) may be formed to be higher than the stacking direction height of the bipolar stack cell (11). This is for sealing with the cover plate (40) to be described later, and the first sealing part (21) may protrude by a predetermined height in the stacking direction of the bipolar stack cell (11) from the top and bottom, respectively. The protruding portion of the first sealing part (21) may be sealed with the inner surface of the cover plate (40).

[0049] FIG. 4 shows a structural diagram of a bipolar secondary battery according to one embodiment of the present invention. FIG. 5 is a schematic perspective view showing the combined form of a cover plate (40) and a side frame (30) of a bipolar secondary battery according to one embodiment of the present invention. FIG. 6 is a plan view showing the shape of a side frame (30) of a bipolar secondary battery according to one embodiment of the present invention.

[0050] Referring to FIGS. 4 to 6, a bipolar secondary battery according to one embodiment of the present invention may include a bipolar stack cell (11 in FIG. 2), a first sealing part (21), and a side frame (30).

[0051] As described above, the bipolar stack cell (11) can be formed as a stacked structure of a plurality of bipolar unit cells (10) and an electrolyte membrane (12), and the stacked bipolar stack cell (11) can be sealed and supported by a first sealing portion (21) formed to surround the edge of the bipolar stack cell (11).

[0052] The side frame (30) can surround the bipolar stack cell (11) by being spaced apart in a horizontal direction perpendicular to the stacking direction of the first sealing part (21) and the bipolar stack cell (11). A spaced gap may be formed between the side frame (30) and the first sealing part (21). The side frame (30) may be arranged in a manner that surrounds the first sealing part (21). The side frame (30) is an insulating rigid body having a predetermined rigidity and may form the structural framework of the bipolar secondary battery. The side frame (30) may be provided to protect the stacked bipolar stack cell (11) from external shock / pressure.

[0053] A bipolar secondary battery according to one embodiment of the present invention may further include a cover plate (40). The cover plate (40) may be formed of a conductive material, such as metal, to transfer power from the bipolar secondary battery to the outside. Through the cover plate (40), power from the bipolar stack cell (11) may be transferred to an external circuit or connected to an adjacent bipolar secondary battery.

[0054] The cover plate (40) may overlap the bipolar stack cell (11) in the stacking direction. The cover plate (40) may be provided as a pair. The cover plate (40) may include a first cover plate (41) that overlaps the upper side of the bipolar stack cell (11) and a second cover plate (42) that overlaps the lower side of the bipolar stack cell (11). The first cover plate (41) and the second cover plate (42) may have the same size and shape. The first cover plate (41) and the second cover plate (42) may be sealed and combined with a first sealing part (21) that seals the bipolar stack cell (11). Specifically, the first sealing part (21), which protrudes by a predetermined height from the top and bottom respectively in the stacking direction of the bipolar stack cell (11), may be fused and combined with the first cover plate (41) and the second cover plate (42). The bipolar stack cell (11) can be located in the horizontal central portion of the first cover plate (41) and the second cover plate (42).

[0055] A bipolar secondary battery according to one embodiment of the present invention may further include a connecting unit (25). The connecting unit (25) may be provided to electrically connect a cover plate (40) and a bipolar stack cell (11) that are spaced apart from each other due to the structure of a first sealing portion (21) protruding at a predetermined height from the end of the stacking direction. The connecting unit (25) may be provided as a pair at the top and bottom of the bipolar stack cell (11) corresponding to a pair of cover plates (40). The connecting unit (25) may be provided with a conductive foam having a predetermined length variability in the stacking direction, but is not limited thereto. The connecting unit (25) may be sealed and fused to the cover plate (40) together with the first sealing portion (21) when the cover plate (40) overlaps the bipolar stack cell (11).

[0056] Referring to FIG. 4, one side of the connecting unit (25) may be positioned to be in contact with the bipolar stack cell (11), and the opposite side of the connecting unit (25) may be positioned to be in contact with the cover plate (40). The shape or structure of the connecting unit (25) is not limited to that shown in FIG. 4, and it may have any shape as long as it can electrically connect the bipolar stack cell (11) and the cover plate (40). A second sealing portion (22) may be provided in the side frame (30). The second sealing portion (22) may be provided to secondarily seal the bipolar stack cell (11) sealed by the first sealing portion (21) from the outside, and at least a portion of the second sealing portion may be located between the metal plate (40) and the side frame (30) to fix and support them. The structure of the second sealing portion (22) will be described in more detail in FIG. 7, which will be described later.

[0057] The side frame (30) may be provided as a picture frame having an overall rectangular shape to surround a bipolar stack cell (11) having a stacked rectangular plate shape, but is not limited thereto. The side frame (30) may be formed in a shape in which a plurality of beams are combined. For example, the side frame (30) may be provided by combining a pair of first frames (301) that extend in the length direction of the bipolar stack cell (11) perpendicular to the stacking direction of the bipolar stack cell (11), and a pair of second frames (302) that extend in the width direction of the bipolar stack cell (11) perpendicular thereto, and these may be combined by a method such as thermal fusion, ultrasonic fusion, or laser fusion.

[0058] FIG. 7 is a drawing showing the sealing structure of the second sealing portion (22) of a bipolar secondary battery according to one embodiment of the present invention.

[0059] Referring to FIG. 7, a side frame (30) of a bipolar secondary battery according to one embodiment of the present invention may be spaced apart from a first sealing portion (21) to form a spaced-apart space (35). The spaced-apart space (35) can effectively release heat generated from the bipolar stack cell (11) to the outside, and since heat is not directly transferred to the side frame (30), deformation of the side frame (30) can be prevented and the thermal stability of the bipolar secondary battery can be improved. In addition, since the bipolar stack cell (11) and the side frame (30) are not in direct contact, vibrations or shocks from the outside may not be directly transmitted to the bipolar stack cell (11), and mechanical stress may be reduced.

[0060] A pair of cover plates (41, 42) can be spaced apart from each other with a side frame (30) in between. With this structure, a pair of cover plates (41, 42) formed of a conductive material can be prevented from coming into contact with each other and causing an electrical short circuit. To implement this, the side frame (30) may include a frame body (31) extending in the stacking direction of the bipolar stack cell (11) between the first cover plate (41) and the second cover plate (42), and an insulating part (32) provided on the frame body (31). The insulating part (32) only needs to be in a shape that provides insulation between the first cover plate (41) and the second cover plate (42), but for example, the insulating part (32) may be provided in the form of a protrusion that protrudes outward with a predetermined width between the spaced-apart first cover plate (41) and the second cover plate (42).

[0061] In each of the pair of cover plates (41, 42), a stepped portion (43) may be formed with a predetermined width so that appropriate fastening pressure can be applied to the central bipolar stack cell (11). The stepped portion (43) may be arranged to be stepped inward toward the bipolar stack cell (11).

[0062] A second sealing portion (22) may be provided in the side frame (30). As described above, the second sealing portion (22) may be provided to secondarily seal the bipolar stack cell (11) sealed by the first sealing portion (21) from the outside. By adopting this double sealing structure, the bipolar cell according to one embodiment of the present invention can not only improve protection performance against the external environment but also stably suppress thermal expansion or chemical reactions of the electrolyte that may occur in the bipolar stack cell (11) through the double sealing, and can disperse thermal or chemical stress into the gap space (35) between the first sealing portion (21) and the second sealing portion (22).

[0063] The second sealing portion (22) may be formed on the outer surface of the side frame (30). The second sealing portion (22) may fuse and fix the side frame (30) and the cover plates (41, 42). The second sealing portion (22) may include a plate sealing portion (221) and a side sealing portion (222). The plate sealing portion (221) and the side sealing portion (222) may be spaced apart from each other. The plate sealing portion (221) may be formed at the stacking direction end of the frame body (31) of the side frame (30) so as to be sealed with the cover plates (41, 42) (wherein 'stacking direction' refers to the stacking direction of the bipolar stack cell (11)). The plate sealing portion (221) may be provided as a pair at both ends of the stacking direction of the frame body (31). The side sealing portion (222) may be formed to overlap the insulating portion (32) of the side frame (30) to seal the space between the first cover plate (41) and the second cover plate (42). The side sealing portion (222) overlaps the insulating portion (32) of the side frame (30) and may include a first area (2221) that contacts the inner surface of the cover plates (41, 42) and a second area (2222) that protrudes to the outside of the cover plates (41, 42), and the first area (2221) and the second area (2222) may be integrally connected.

[0064] FIG. 8 is a diagram showing the structure of a bipolar secondary battery according to another embodiment of the present invention.

[0065] In another embodiment of the present invention, there may be differences from the previous embodiments in the structural form of the cover plate (41, 42) and the side frame (30). Except for the differences, the description of the remaining components can be applied in the same way to this embodiment, so common details will be omitted and the description will focus on the differences.

[0066] Referring to FIG. 8, a bipolar secondary battery according to another embodiment of the present invention may include a bipolar stack cell, a first sealing part (21), a second sealing part (22), a side frame (30), and a pair of cover plates (41, 42).

[0067] The cover plates (41, 42) can be provided in a flat shape without a separate step structure. In this case, in the stacked structure between bipolar secondary batteries, the cover plates (41, 42) can be in close contact with the cover plates (41, 42) of adjacent bipolar secondary batteries without any gaps.

[0068] The side frame (30) may be provided in a form that extends between the first cover plate (41) and the second cover plate (42) without a separate protruding structure. In this case, the side frame (30) may be provided to have a structure that is relatively simpler than that of the preceding embodiment. Furthermore, the side frame (30) and the first sealing part (21) may be provided in a form that is in close contact without a separate gap.

[0069] The first cover plate (41) and the second cover plate (42) may be spaced apart from each other with the side frame (30) in between. The thickness of the side frame (30) may be formed to an appropriate value that forms electrical insulation between the first cover plate (41) and the second cover plate (42).

[0070] Additionally, the side frame (30) may not have a separate insulating part or protrusion protruding outward. In this case, the second sealing part (22) may be formed between the side frame (30) and the cover plates (41, 42). The first sealing part (21) and the second sealing part (22) may not only be in a separated form, but may also be connected to each other or formed integrally as needed, and their forms may not be particularly limited.

[0071] FIG. 9 is a schematic diagram showing the process of forming a first sealing portion (21) of a bipolar secondary battery according to one embodiment of the present invention. FIG. 10 is a schematic diagram showing the shape of a first sealing portion (21) of a bipolar secondary battery according to one embodiment of the present invention.

[0072] Referring to FIGS. 9 and 10, the first sealing portion (21) of a bipolar secondary battery according to one embodiment of the present invention may include a plurality of layers (211, 212) made of different materials. In one embodiment of the present invention, sealing may be performed in a form in which a unit shape (210) of a laminated film, which is composed of a stack of a first layer (211) and a second layer (212) having different properties, is heat-fused in the stacking direction at the edge of a bipolar unit cell (10). The unit shape (210) of the laminated film may be in a form in which the first layer (211) is adhered to both sides with the second layer (212) in between, and in this case, the fusion between the laminated films may be performed between the first layers (211) of adjacent laminated films. When using a laminated film shape, the processability and efficiency of manufacturing can be improved using a pre-manufactured film.

[0073] The first layer (211) and the second layer (212) may be made of materials having different properties, for example, one layer may be configured to provide chemical stability and the other layer to provide structural strength. The material of each layer may include PP (Polypropylene), PET (Polyethylene Terephthalate), Nylon (Polyamide), PPa (Acid-Modified PP), or a combination thereof, but is not limited thereto.

[0074] FIG. 11 is a schematic diagram showing the process of forming a first sealing portion (21) of a bipolar secondary battery according to another embodiment of the present invention. FIG. 12 is a schematic diagram showing the shape of a first sealing portion (21) of a bipolar secondary battery according to another embodiment of the present invention.

[0075] Referring to FIGS. 11 and 12, the bipolar secondary battery according to another embodiment of the present invention differs from the previous embodiment in that the configuration and stacking shape of the first sealing portion (21) may be partially changed, and the description of the remaining components excluding the differences may be applied commonly as described in the previous embodiment.

[0076] According to another embodiment of the present invention, the first sealing portion (21) of a bipolar secondary battery may include a plurality of layers (211, 212) made of different materials. In another embodiment of the present invention, the plurality of layers (211, 212) may be formed by fusion and lamination of individual layers, rather than in the form of a laminated film, during the process of forming the first sealing portion (21). For example, a pair of first layers (211) and a second layer (212) placed below them may be fused and sealed in the lamination direction. In this case, by arranging the layers step by step during the assembly process of the bipolar secondary battery, adjustments can be made for each layer, thereby improving design flexibility.

[0077] As described above, the embodiments have been explained with specific details such as specific components, limited embodiments, and drawings, but this is provided to aid in the overall understanding. Furthermore, the present invention is not limited to the embodiments described above, and various modifications and variations are possible from this description by those skilled in the art. Therefore, the scope of the present invention should not be limited to the embodiments described above, and all things equivalent to or having equivalent variations to the claims set forth below, as well as the claims themselves, shall be considered to fall within the scope of the concept of the present invention.

[0078] [Explanation of the symbol]

[0079] 10 bipolar unit cells

[0080] 101 Electrode Plate

[0081] 102 cathode layer

[0082] 103 anode layer

[0083] 11 bipolar stack cell

[0084] 12 electrolyte membranes

[0085] 21 First sealing part

[0086] 22 Second sealing part

[0087] 35 gaps

[0088] 221 Plate sealing section

[0089] 222 Side sealing part

[0090] 2221 Area 1

[0091] 2222 Area 2

[0092] 25 connection units

[0093] 30 side frame

[0094] 301 First Frame

[0095] 302 Second Frame

[0096] 31 Frame Body

[0097] 32 Insulation section

[0098] 40 cover plates

[0099] 41 First cover plate

[0100] 42 Second cover plate

[0101] 43 Step section

Claims

1. A bipolar stack cell comprising a plurality of bipolar unit cells that are stacked together along a stacking direction, wherein an anode layer is formed on one side of an electrode plate and a cathode layer is formed on the other side, and an electrolyte membrane disposed between adjacent bipolar unit cells; A first sealing portion surrounding and sealing the above-mentioned bipolar stack cell; and A bipolar secondary battery comprising a side frame spaced apart from the first sealing portion and surrounding the bipolar stack cell, and having a second sealing portion that seals the bipolar stack cell from the outside.

2. In Paragraph 1, A bipolar secondary battery further comprising a pair of cover plates that overlap the bipolar stack cell in the stacking direction to transfer power of the bipolar stack cell to the outside.

3. In Paragraph 2, A bipolar secondary battery, wherein the second sealing portion is formed between the side frame and the cover plate.

4. In Paragraph 2, A bipolar secondary battery, wherein the second sealing portion is formed along the edge of the cover plate.

5. In Paragraph 2, A bipolar secondary battery in which the height of the stacking direction of the first sealing portion is higher than the height of the stacking direction of the bipolar stack cell.

6. In Paragraph 2, A bipolar secondary battery, wherein the first sealing portion protrudes from the bipolar stack cell by a predetermined height in the stacking direction, and the protruding first sealing portion is sealed with the inner surface of the pair of cover plates.

7. In Paragraph 2, A bipolar secondary battery, wherein the above pair of cover plates includes a first cover plate that overlaps the top of the bipolar stack cell and a second cover plate that overlaps the bottom of the bipolar stack cell, and the first cover plate and the second cover plate are spaced apart from each other with the side frame in between.

8. In Paragraph 7, The above side frame is, A frame body disposed between the first cover plate and the second cover plate to support the above pair of cover plates; and A bipolar secondary battery comprising an insulating portion provided on the frame body to insulate the first cover plate and the second cover plate.

9. In Paragraph 8, A bipolar secondary battery, wherein the insulating portion is formed to protrude from the frame body between the spaced-apart first cover plate and the second cover plate.

10. In Paragraph 8, The above second sealing part is, A plate sealing portion formed at the end of the frame body in the stacking direction to be sealed with the above pair of cover plates; and A bipolar secondary battery comprising a side sealing portion that overlaps the insulating portion to seal the space between the first cover plate and the second cover plate.

11. In Paragraph 1, A bipolar secondary battery in which the end of the electrode plate is inserted horizontally and supported in the first sealing portion.

12. In Paragraph 1, A bipolar secondary battery comprising a plurality of layers made of different materials, wherein the first sealing portion above comprises a plurality of layers.

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