Bipolar secondary battery and bipolar secondary battery assembly including same

Abstract

A bipolar secondary battery assembly according to an embodiment of the present invention may comprise: a plurality of bipolar secondary batteries comprising a bipolar stack cell in which a plurality of bipolar unit cells, each having a positive electrode layer formed on one surface of an electrode plate and a negative electrode layer formed on the other surface of the electrode plate, are stacked, wherein the bipolar secondary batteries are stacked in a stacking direction so as to be electrically connected to each other, and at least a portion of the bipolar secondary batteries are spaced apart in the stacking direction; and support pads provided in the gaps between adjacent bipolar secondary batteries among the bipolar secondary batteries to support the bipolar secondary batteries.

Description

Bipolar secondary battery and bipolar secondary battery assembly including the same

[0001] The present invention relates to a bipolar secondary battery and a bipolar secondary battery assembly including the same. The present application claims the benefit of priority based on Korean Patent Application No. 2024-0185063 filed December 12, 2024 and Korean Patent Application No. 2025-0142612 filed September 30, 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 maintaining electrical contact and structural stability between stacked cells is considered a critical technical challenge. Consequently, there is a demand for bipolar rechargeable battery assemblies equipped with a structure capable of uniformly distributing pressure between stacked cells, stabilizing the stacked structure, and minimizing electrical resistance.

[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] The embodiments of the present invention have been devised in consideration of the aforementioned problems, and

[0006] The problem that the present invention aims to solve is to provide a bipolar secondary battery assembly capable of improving the stability of a stacked structure.

[0007] Another problem that the present invention aims to solve is to provide a bipolar secondary battery assembly that can improve electrical reliability.

[0008] A bipolar secondary battery assembly according to an embodiment of the present invention may include a bipolar stack cell in which a plurality of bipolar unit cells are stacked, 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 a plurality of bipolar secondary batteries are stacked along a stacking direction so as to be electrically connected to each other, with at least one portion spaced apart in the stacking direction; and a support pad provided in a spaced-apart space between adjacent bipolar secondary batteries to support the bipolar secondary batteries.

[0009] The above-described bipolar secondary battery further includes a pair of cover plates that overlap the bipolar stack cell in the stacking direction to transfer power from the bipolar stack cell to the outside, and at least one portion of the cover plates may be arranged to be stepped in the stacking direction of the bipolar stack cell.

[0010] The above bipolar secondary battery may further include a side frame that extends between the pair of cover plates to support the pair of cover plates and is disposed on at least one side of the bipolar stack cell.

[0011] The above cover plate may include: a body portion that overlaps the bipolar stack cell in the stacking direction; a stepped portion formed in a stepped manner in the stacking direction toward the bipolar stack cell; and a side portion that extends outwardly from the stepped portion and overlaps the side frame in the stacking direction.

[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 may be in contact with at least a portion of the second cover plate of the adjacent bipolar secondary battery.

[0013] The body portion of the first cover plate and the body portion of the second cover plate of the adjacent bipolar secondary battery can come into contact with each other.

[0014] The side portion of the first cover plate and the side portion of the second cover plate of the adjacent bipolar secondary battery may be spaced apart from each other in the stacking direction.

[0015] The support pad may extend between the side portion of the first cover plate spaced apart in the stacking direction and the side portion of the second cover plate of the adjacent bipolar secondary battery.

[0016] The height of the above-mentioned side frame in the stacking direction may be smaller than the height in the stacking direction between the body portion of the first cover plate and the body portion of the second cover plate.

[0017] The above support pad may be formed of conductive resin or thermal resin.

[0018] A bipolar secondary battery according to one embodiment of the present invention may include: a bipolar stack cell in which a plurality of bipolar unit cells are stacked, 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; a pair of cover plates that overlap the bipolar stack cell in a stacking direction to transfer power from the bipolar stack cell to the outside, wherein at least one portion is stepped in the stacking direction of the bipolar stack cell; and a side frame that extends between the pair of cover plates and is spaced apart from the bipolar stack cell to support the pair of cover plates.

[0019] The bipolar secondary battery assembly according to an embodiment of the present invention can have improved stability of the stacked structure.

[0020] The electrical reliability of a bipolar secondary battery assembly according to an embodiment of the present invention can be improved.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] FIG. 3 is a schematic diagram showing the structure of a bipolar stack cell and a sealing portion of a bipolar secondary battery according to one embodiment of the present invention.

[0025] FIG. 4 is a 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.

[0026] FIG. 5 shows a schematic structural diagram of a bipolar secondary battery according to one embodiment of the present invention.

[0027] FIG. 6 is a partial structural diagram showing the step structure of a cover plate of a bipolar secondary battery according to one embodiment of the present invention.

[0028] FIG. 7 is a schematic structural diagram of a bipolar secondary battery assembly according to one embodiment of the present invention.

[0029] FIG. 8 is a diagram showing the structure of a bipolar secondary battery according to another embodiment of the present invention.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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).

[0039] 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).

[0040] 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).

[0041] 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 a direction 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).

[0042] The electrolyte membrane (12) is positioned between adjacent bipolar unit cells (10) to enable ion conduction and block electron flow, thereby preventing short circuits. This stacked structure of multiple 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 multiple bipolar unit cells (10) are connected in electrical series. The electrolyte membrane (12) may be formed as a solid with a certain 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, the electrolyte may be impregnated into the separator and then cured to be used as a gel type, or the electrolyte may be 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, and structural stability can be improved.

[0043] FIG. 3 is a schematic diagram showing the structure of a bipolar stack cell (11) and a sealing part (21) of a bipolar secondary battery according to one embodiment of the present invention.

[0044] Referring to FIG. 3, a bipolar secondary battery according to one embodiment of the present invention may include a sealing portion (21).

[0045] The sealing portion (21) can surround and seal the bipolar stack cell (11). The sealing portion (21) can be formed along the outer edge of the bipolar stack cell (11). The 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 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 sealing portion (21). The 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 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 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 sealing portion (21).

[0046] A bipolar stack cell (11) that is sealed and surrounded by a sealing portion (21) may 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) may 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 may have different electrical polarities due to the anode / cathode layers that are in contact with each other.

[0047] The stacking direction height of the sealing portion (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 sealing portion (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 sealing portion (21) may be sealed with the inner surface of the cover plate (40).

[0048] FIG. 4 is a 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. FIG. 5 shows a schematic structural diagram of a bipolar secondary battery according to one embodiment of the present invention.

[0049] Referring to FIGS. 4 and 5, a bipolar secondary battery according to one embodiment of the present invention may include a bipolar stack cell (11 in FIG. 2), a sealing portion (21), and a side frame (30).

[0050] 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.

[0051] 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 top of the bipolar stack cell (11) and a second cover plate (42) that overlaps the bottom of the bipolar stack cell (11). For example, 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 sealing portion (21) that seals the bipolar stack cell (11). Specifically, the sealing portion (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).

[0052] The cover plate (40) may be provided with at least one portion stepped in the stacking direction of the bipolar stack cell (11). By forming a portion of the cover plate (40) in a stepped shape, an appropriate level of pressure can be applied to the bipolar stack cell (11) in the stacking direction, thereby reducing the electrical contact resistance inside the stack cell, improving charge / discharge efficiency, and also improving structural stability. The stepped structure of the cover plate (40) will be described in more detail in FIG. 6, which will be described later.

[0053] The side frame (30) may extend between the pair of cover plates (40) to support the pair of cover plates (40). The side frame (30) may extend between the first cover plate (41) and the second cover plate (42). The side frame (30) may be provided spaced apart from the bipolar stack cell (11). Specifically, the side frame (30) may surround the bipolar stack cell (11) by being spaced apart in a horizontal direction perpendicular to the stacking direction of the sealing portion (21) and the bipolar stack cell (11). A spaced-out space may be formed between the side frame (30) and the sealing portion (21). The side frame (30) may be arranged in a manner that surrounds the sealing portion (21). The side frame (30) may be 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 impact / pressure. The side frame (30) may be provided as a picture frame having an overall rectangular shape to surround the 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.

[0054] A bipolar secondary battery according to one embodiment of the present invention may further include a frame sealing portion (22). The frame sealing portion (22) may be provided on a side frame (30). The frame sealing portion (22) may be provided to secondarily seal the bipolar stack cell (11) sealed by the sealing portion (21) from the outside, and at least a portion of the frame sealing portion may be located between the cover plate (40) and the side frame (30) to fix and support them.

[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 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 sealing portion (21) when the cover plate (40) overlaps the bipolar stack cell (11).

[0056] Referring to FIG. 5, 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).

[0057] In contrast, it should be noted that if the stacking direction end of the bipolar stack cell comes into direct contact with the inner surface of the cover plate (40) or is electrically connected through a separate means, the configuration of the connection unit (25) may not be adopted.

[0058] FIG. 6 is a partial structural diagram showing the step structure of a cover plate of a bipolar secondary battery according to one embodiment of the present invention.

[0059] Referring to FIG. 6, a pair of cover plates (41, 42) may be spaced apart from each other with a side frame (30) in between. The side frame (30) supports the pair of cover plates (41, 42) so that they maintain a predetermined distance from each other in the vertical direction (or stacking direction), thereby preventing the pair of cover plates (41, 42), formed of a conductive material, 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) is sufficient if it is in a form 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).

[0060] A predetermined spacing space (35) may be formed between the sealing portion (21) surrounding the bipolar stack cell (11) and the side frame (30), but is not limited thereto, and as in the embodiment to be described later, there may be no spacing space (35) between the sealing portion (21) and the side frame (30).

[0061] Each of the pair of cover plates (41, 42) may have a stepped portion (402) formed therein in a stacking direction toward the bipolar stack cell (11). Specifically, each of the pair of cover plates (41, 42) may include a body portion (401), a stepped portion (402), and a side portion (403).

[0062] The body portion (401) is provided in the central part of the cover plates (41, 42) and may be a portion that overlaps the bipolar stack cell (11) in the stacking direction. The body portion (401) may be provided to contact the cover plate of an adjacent bipolar secondary battery as described below. The body portion (401) may extend in a horizontal direction perpendicular to the stacking direction of the bipolar stack cell (11). The stacking direction height of the bipolar stack cell (11) may correspond to the stacking direction distance between the body portion (401) of the first cover plate (41) and the body portion (401) of the second cover plate (42).

[0063] The step portion (402) may extend from the end of the body portion (401). The step portion (402) may be provided to be stepped in the stacking direction toward the bipolar stack cell (11). The step portion (402) may be provided to be inclined at a predetermined angle with respect to the horizontal direction. The step portion (402) may extend between the body portion (401) and the side portion (403). The step portion (402) may be provided in a shape that is recessed with a predetermined width from the end of the body portion (401) toward the stacking direction of the bipolar stack cell (11), and the recessed width of the step portion (402) may be appropriately varied as needed to evenly distribute the pressure applied in the stacking direction and to ensure electrical and structural stability.

[0064] The side portion (403) may extend from the stepped portion (402) and be located at the outer edge of the cover plates (41, 42). The side portion (403) may overlap the side frame (30) in the stacking direction. The side portion (403) may be combined with the side frame (30) via the frame sealing portion (22) described above. The side frame (30) may extend between the side portion (403) of the first cover plate (41) and the side portion (403) of the second cover plate (42). Accordingly, the stacking direction height of the side frame (30) may correspond to the stacking direction distance between the side portion (403) of the first cover plate (41) and the side portion (403) of the second cover plate (42).

[0065] Due to the structure of the step portion (402) which is recessed with a predetermined width in the stacking direction toward the bipolar stack cell (11), the stacking direction distance between the side portion (403) of the first cover plate (41) and the side portion (403) of the second cover plate (42) may be smaller than the stacking direction distance (or height) between the body portion (401) of the first cover plate (41) and the body portion (401) of the second cover plate (42). Alternatively, the height of the side frame (30) in the stacking direction may be smaller than the height in the stacking direction of the space where the bipolar stack cell (11) is placed between the first cover plate (41) and the second cover plate (42). In this way, by forming the gap between a pair of cover plates (41, 42) relatively narrow in the part that overlaps the side frame (30) and relatively wide in the part that overlaps the bipolar stack cell (11), the pair of cover plates (41, 42) can continuously apply a predetermined surface pressure to the bipolar stack cell (11) during the charging and discharging process of the bipolar stack cell (11).

[0066] FIG. 7 is a schematic structural diagram of a bipolar secondary battery assembly according to one embodiment of the present invention.

[0067] Referring to FIG. 7, a bipolar secondary battery assembly according to one embodiment of the present invention may comprise a plurality of the above-described bipolar secondary batteries. A bipolar secondary battery assembly according to one embodiment of the present invention may be provided by stacking a plurality of bipolar secondary batteries. A plurality of bipolar secondary batteries may be stacked in a stacking direction so as to be electrically connected to each other.

[0068] The first cover plate (41) of each bipolar secondary battery can be electrically connected to the second cover plate (42) of an adjacent bipolar secondary battery by contacting at least a portion thereof. The first cover plate (41) of each bipolar secondary battery can come into contact with the second cover plate (42) of an adjacent bipolar secondary battery at the body portion (401). Due to the structure of the body portion (401) of the adjacent bipolar secondary batteries that come into contact with each other, an appropriate level of pressure can be applied to the bipolar stack cell (11) of each bipolar secondary battery in the stacking direction.

[0069] Due to the structure of the step portion (402), the side portion (403) of the first cover plate (41) of each bipolar secondary battery and the side portion (403) of the second cover plate (42) of an adjacent bipolar secondary battery can be spaced apart from each other in the stacking direction.

[0070] A bipolar secondary battery assembly according to one embodiment of the present invention may include a support pad (50). The support pad (50) may be provided to support a stacked bipolar secondary battery and may be formed in a spaced-apart space between adjacent bipolar secondary batteries. The support pad (50) may extend between a side portion (403) of a first cover plate (41) spaced apart in the stacking direction and a side portion (403) of a second cover plate (42) of an adjacent bipolar secondary battery.

[0071] The support pad (50) can be formed as a foam-like filling structure that fills the space between the side portion (403) of the first cover plate (41) spaced apart in the stacking direction and the side portion (403) of the second cover plate (42) of the adjacent bipolar secondary battery. By forming the support pad (50) in this form, the gap between the stacked bipolar secondary battery structures can be filled, and movement between the stacked bipolar secondary batteries can be minimized, and the electrical connection can also be maintained stably.

[0072] When having a foam-type structure, the support pad provides a shock absorption effect, preventing external vibrations or shocks from being directly transmitted to the bipolar secondary battery, and the stability of the battery assembly can be further enhanced. However, it should be noted that the shape of the support pad (50) is not limited to what is described above.

[0073] The support pad (50) can be formed from various materials such as conductive resin, thermal resin, or composite materials with enhanced mechanical strength. The conductive resin facilitates the flow of current between bipolar secondary batteries through electrical contact and can serve to reduce electrical resistance. The thermal resin can effectively dissipate heat generated between bipolar secondary batteries to prevent overheating and contribute to extending the lifespan of the batteries. The support pad can fix neighboring bipolar secondary batteries while simultaneously performing electrical connection or thermal management functions, thereby significantly improving the performance and reliability of the bipolar secondary batteries.

[0074] FIG. 8 is a diagram showing the structure of a bipolar secondary battery according to another embodiment of the present invention.

[0075] In another embodiment of the present invention, there may be differences from the previous embodiment 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.

[0076] Referring to FIG. 8, a bipolar secondary battery according to another embodiment of the present invention may include a bipolar stack cell, a sealing portion (21), a frame sealing portion (22), a side frame (30), and a pair of cover plates (41, 42).

[0077] 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.

[0078] 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 sealing part (21) may be provided in a form that is in close contact without a separate gap.

[0079] 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).

[0080] Additionally, the side frame (30) may not have a separate insulating part or protrusion protruding outward. In this case, the frame sealing part (22) may be formed between the side frame (30) and the cover plate (41, 42). The sealing part (21) and the frame 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.

[0081] In the case where a plurality of bipolar secondary batteries according to another embodiment of the present invention are stacked, the support pad (50) in the preceding embodiment may be provided in the form of a thin sheet provided between the first cover plate (41) and the second cover plate (42), but is not limited thereto and may be provided in various forms located between the first cover plate (41) and the second cover plate (42).

[0082] The bipolar secondary battery assembly according to the present invention can be provided in various forms depending on the design purpose and usage environment. For example, the bipolar secondary battery according to the present invention can be provided as a secondary battery module. In this case, a battery pack can be formed by combining a plurality of secondary battery modules equipped with the bipolar secondary battery assembly according to the present invention. Alternatively, the bipolar secondary battery assembly according to the present invention may be provided directly in the form of a pack without a separate modularization process. In this case, the bipolar secondary battery assembly can be directly integrated into the battery pack based on the structural stability described above, thereby improving the space utilization efficiency and energy density of the battery pack.

[0083] 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.

[0084] [Explanation of the symbol]

[0085] 10 bipolar unit cells

[0086] 101 Electrode Plate

[0087] 102 cathode layer

[0088] 103 anode layer

[0089] 11 bipolar stack cell

[0090] 12 electrolyte membranes

[0091] 21 Sealing part

[0092] 22 Frame sealing part

[0093] 35 gaps

[0094] 25 connection units

[0095] 30 side frame

[0096] 31 Frame Body

[0097] 32 Insulation section

[0098] 40 cover plates

[0099] 41 First cover plate

[0100] 42 Second cover plate

[0101] 401 body

[0102] 402 Step section

[0103] 403 Side

[0104] 50 support pads

Claims

1. A plurality of bipolar secondary batteries comprising a bipolar stack cell in which a plurality of bipolar unit cells are stacked, 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 wherein the bipolar unit cells are stacked along a stacking direction so as to be electrically connected to each other, but at least one portion is spaced apart in said stacking direction; and A bipolar secondary battery assembly comprising a support pad provided in a spaced-apart space between adjacent bipolar secondary batteries to support the bipolar secondary batteries.

2. In Paragraph 1, The above-mentioned bipolar secondary battery is, The apparatus further includes a pair of cover plates that overlap the bipolar stack cell in the stacking direction to transfer power from the bipolar stack cell to the outside, and A bipolar secondary battery assembly in which at least one portion of the above-mentioned cover plate is arranged to be stepped in the stacking direction of the above-mentioned bipolar stack cell.

3. In Paragraph 2, The above-mentioned bipolar secondary battery is, A bipolar secondary battery assembly further comprising a side frame extending between the pair of cover plates to support the pair of cover plates and disposed on at least one side of the bipolar stack cell.

4. In Paragraph 3, The above cover plate is, A body portion that overlaps the above bipolar stack cell in the stacking direction; A stepped portion formed with a step in the stacking direction toward the above bipolar stack cell; and A bipolar secondary battery assembly comprising a side portion that extends outwardly to the stepped portion and overlaps the side frame in the stacking direction.

5. In Paragraph 4, 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. A bipolar secondary battery assembly in which the first cover plate is in contact with at least a portion of the second cover plate of the adjacent bipolar secondary battery.

6. In Paragraph 5, A bipolar secondary battery assembly in which the body portion of the first cover plate and the body portion of the second cover plate of the adjacent bipolar secondary battery are in contact with each other.

7. In Paragraph 5, A bipolar secondary battery assembly in which the side portion of the first cover plate and the side portion of the second cover plate of the adjacent bipolar secondary battery are spaced apart from each other in the stacking direction.

8. In Paragraph 7, The above support pad is a bipolar secondary battery assembly extending between the side portion of the first cover plate spaced apart in the stacking direction and the side portion of the second cover plate of the adjacent bipolar secondary battery.

9. In Paragraph 5, A bipolar secondary battery assembly in which the height of the stacking direction of the side frame is smaller than the height in the stacking direction between the body portion of the first cover plate and the body portion of the second cover plate.

10. In Paragraph 1, The above support pad is formed of a conductive resin or thermal resin, forming a bipolar secondary battery assembly.

11. A bipolar stack cell in which a plurality of bipolar unit cells are stacked, wherein an anode layer is formed on one side of an electrode plate and a cathode layer is formed on the other side; 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, wherein at least a portion thereof is stepped in the stacking direction of the bipolar stack cell; and A bipolar secondary battery comprising a side frame extending between the pair of cover plates and spaced apart from the bipolar stack cell to support the pair of cover plates.

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