Secondary battery

Abstract

A secondary battery is provided comprising: a stacked electrode assembly having a plurality of unit cells stacked in a first direction and electrode leads at both ends of a second direction perpendicular to the first direction; a multifunctional terminal block (MTB) provided at at least one end of the stacked electrode assembly; and a laminate sheet wrapping the side of the stacked electrode assembly to define an internal cell space.

Description

Technology Field

[0001] The present invention relates to a secondary battery, and more specifically, to a secondary battery capable of effectively discharging internally generated gas and preventing moisture penetration. Background Technology

[0002] Unlike primary batteries, secondary batteries can be charged and discharged multiple times. Secondary batteries are widely used as energy sources for various wireless devices such as handsets, laptops, and cordless vacuum cleaners. Recently, as the manufacturing cost per unit capacity of secondary batteries has decreased dramatically due to improved energy density and economies of scale, and as the driving range of BEVs (battery electric vehicles) has increased to a level equivalent to that of fuel vehicles, the primary use of secondary batteries is shifting from mobile devices to mobility.

[0003] Meanwhile, the demand for high-capacity battery packs applied to electric vehicles and the like has recently been increasing. High-capacity battery packs installed in automobiles are required to enhance safety along with increasing capacity. Prior art literature

[0004] Republic of Korea Patent Publication No. 10-2017-0014293 The problem to be solved

[0005] The technical problem that the present invention aims to solve is to provide a secondary battery capable of effectively discharging internally generated gas and preventing moisture penetration. means of solving the problem

[0006] To achieve the above technical objective, the present invention provides a secondary battery comprising: a stacked electrode assembly having a plurality of unit cells stacked in a first direction and electrode leads at both ends of a second direction perpendicular to the first direction; a multifunctional terminal block (MTB) provided at least one end of the stacked electrode assembly; and a laminate sheet covering the side of the stacked electrode assembly to define an internal cell space. The MTB may include an electrode terminal portion electrically connected to the electrode leads of the stacked electrode assembly; a check valve configured to discharge gas in the internal cell space exceeding a first pressure; and a rupture disk configured to rupture and discharge gas when the pressure in the internal cell space increases to a second pressure exceeding the first pressure.

[0007] In some embodiments, the check valve may be configured to switch from a closed state to an open state when the pressure in the cell interior space exceeds the first pressure, and to switch from an open state to a closed state after the pressure in the cell interior space is relieved to a level lower than the first pressure.

[0008] In some embodiments, the check valve may include: a conduit portion communicating with the cell internal space and open to the outside of the secondary battery; a valve packing provided within the conduit portion and capable of moving toward the outside of the secondary battery by the pressure of the cell internal space; and an elastic body that causes the valve packing to return to its original position according to the pressure of the cell internal space.

[0009] In some embodiments, the conduit portion includes a first stopper provided at the end of the cell internal space side; and a second stopper provided on the inner circumference of the conduit portion spaced apart from the first stopper, the valve packing is disposed between the first stopper and the second stopper, and the elastic body may be disposed between the valve packing and the second stopper.

[0010] In some embodiments, the check valve includes an O-ring provided between the valve packing and the conduit portion, and the valve packing includes a tapered side having a diameter that decreases toward the cell interior space, and the tapered side may be configured to form the closed state by making hermetic contact with the O-ring and the open state by being spaced apart from the O-ring.

[0011] In some embodiments, the check valve may further include a waterproof membrane at the end of the conduit.

[0012] In some embodiments, the waterproof membrane may include a material that allows carbon dioxide to permeate.

[0013] In some embodiments, the waterproof membrane may comprise two or more laminated thin films.

[0014] In some embodiments, the waterproof membrane may include a first layer of a porous type and a second layer of a non-porous type.

[0015] In some embodiments, the first layer may comprise a fluorine-based polymer film, and the second layer may comprise a silicon-based polymer film.

[0016] In some embodiments, an external collector may be further included that is connected to the check valve to communicate with gas and configured to collect gas discharged from the check valve. In this case, a waterproof membrane may not be included at the end of the conduit.

[0017] Another aspect of the present invention provides a secondary battery comprising: a stacked electrode assembly in which a plurality of unit cells are stacked in a first direction and extend in a second direction perpendicular to the first direction and have an electrode lead at an end; a multifunctional terminal block (MTB) coupled to the electrode lead of the stacked electrode assembly; and a laminate sheet that wraps the stacked electrode assembly together with the MTB to define a cell internal space. The MTB comprises: an electrode terminal portion electrically connected to the electrode lead of the stacked electrode assembly; a bus bar electrically connecting the electrode lead and the electrode terminal portion; and a check valve configured to discharge gas in the cell internal space exceeding a first pressure. The check valve comprises: a conduit portion communicating with the cell internal space and open to the outside of the secondary battery; and a waterproof membrane provided at the outer end of the conduit portion.

[0018] In some embodiments, the waterproof membrane may include a hydrophobic material.

[0019] In some embodiments, the waterproof membrane may have a CO2:N2 permeability ratio of 4:1 to 50:1 when measured according to DIN 53536. Effects of the invention

[0020] The secondary battery according to the embodiments of the present invention has the effect of effectively discharging gas generated internally and preventing moisture penetration.

[0021] The effects obtainable from the exemplary embodiments of the present invention are not limited to those mentioned above, and other unmentioned effects can be clearly derived and understood by those skilled in the art to which the exemplary embodiments of the present disclosure belong from the following description. That is, unintended effects resulting from the implementation of the exemplary embodiments of the present disclosure can also be derived by those skilled in the art from the exemplary embodiments of the present disclosure. Brief explanation of the drawing

[0022] FIG. 1a is a perspective view showing the main parts of a secondary battery according to one embodiment of the present invention. FIG. 1b is a partial perspective view showing an enlarged portion of the secondary battery of FIG. 1a. FIG. 2 is a schematic perspective view showing the laminate sheet removed from the secondary battery of FIG. 1. FIG. 3 is a schematic diagram showing a cross-section of the first MTB cut by a plane perpendicular to the third direction passing through the electrode terminal portion. FIG. 4a is a cross-sectional view showing a check valve according to one embodiment of the present invention. FIG. 4b is a cross-sectional view showing the check valve in an open state. FIG. 5 is a partially exploded perspective view showing a bonding method of a laminate sheet of a secondary battery according to one embodiment of the present invention. FIG. 6 is a partial cross-sectional view of a laminate sheet according to one embodiment of the present invention. FIG. 7a is a perspective view showing the main parts of a secondary battery according to one embodiment of the present invention. FIG. 7b is a partial perspective view showing an enlarged portion of the secondary battery of FIG. 7a. FIG. 8 is a side view of a secondary battery according to another embodiment of the present invention. FIG. 9 is a perspective view showing the main parts of a secondary battery according to another embodiment of the present invention. Specific details for implementing the invention

[0023] Hereinafter, preferred embodiments of the concept of the present invention will be described in detail with reference to the accompanying drawings. However, embodiments of the concept of the present invention may be modified in various different forms, and the scope of the concept of the present invention should not be interpreted as being limited by the embodiments described below. It is preferable to interpret the embodiments of the concept of the present invention as being provided to more completely explain the concept of the present invention to those with average knowledge in the art. Identical reference numerals denote identical elements throughout. Furthermore, various elements and areas in the drawings are depicted schematically. Accordingly, the concept of the present invention is not limited by the relative sizes or spacing depicted in the accompanying drawings.

[0024] Terms such as first, second, etc. may be used to describe various components, but said components are not limited by said terms. These terms are used solely for the purpose of distinguishing one component from another. For example, without departing from the scope of the concept of the present invention, the first component may be named the second component, and conversely, the second component may be named the first component.

[0025] The terms used in this application are used merely to describe specific embodiments and are not intended to limit the concept of the invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this application, expressions such as "comprising" or "having" are intended to indicate the existence of the features, number, 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, actions, components, parts, or combinations thereof.

[0026] Unless otherwise defined, all terms used herein, including technical and scientific terms, have the same meaning as commonly understood by those skilled in the art to which the concept of the present invention pertains. Furthermore, it will be understood that commonly used terms, such as those defined in advance, should be interpreted as having meanings consistent with their intent in the context of the relevant technology, and should not be interpreted in an overly formal sense unless explicitly defined herein.

[0027] Where an embodiment can be implemented differently, a specific process sequence may be performed differently from the order described. For example, two processes described in succession may be performed substantially simultaneously or in the reverse order of the description.

[0028] In the accompanying drawings, variations of the depicted shapes may be expected, for example, depending on manufacturing technology and / or tolerances. Accordingly, embodiments of the present invention should not be interpreted as being limited to specific shapes of the areas depicted herein, but should include, for example, variations in shape resulting from the manufacturing process. All terms "and / or" used herein include each of the mentioned components and all combinations of one or more thereof. Additionally, the term "substrate" as used herein may refer to the substrate itself, or a laminated structure including the substrate and a certain layer or film formed on its surface. Furthermore, the term "surface of the substrate" in this specification may refer to the exposed surface of the substrate itself, or the outer surface of a certain layer or film formed on the substrate.

[0029] (1st embodiment)

[0030] FIG. 1a is a perspective view showing a main part of a secondary battery (100) according to one embodiment of the present invention. FIG. 1b is a partial perspective view showing an enlarged portion of the secondary battery (100) of FIG. 1a. FIG. 2 is a schematic perspective view showing the secondary battery (100) of FIG. 1a with the laminate sheet (130) removed.

[0031] In the drawings below, the secondary battery (100) is shown as being defined in a vertical coordinate system defined by a first direction along the X-axis, a second direction along the Y-axis, and a third direction along the Z-axis, which are perpendicular to each other, but the first direction, the second direction, and the third direction only need to be perpendicular to each other and are not particularly limited.

[0032] Referring to FIGS. 1a to 2, the secondary battery (100) includes a stacked electrode assembly (110), a multifunctional terminal block (MTB) (120a, 120b), and a laminate sheet (130).

[0033] The stacked electrode assembly (110) may include a plurality of unit cells (111) stacked in a first direction (e.g., the X-axis direction). Each of the unit cells (111) may have an electrode material applied on a metal foil that acts as a current collector.

[0034] Each unit cell (111) may have a thin plate-like body extending in a second direction (e.g., the Y-axis direction). Each unit cell (111) may be a positive unit cell or a negative unit cell. In some embodiments, the plurality of unit cells (111) may be a positive unit cell and a negative unit cell stacked alternately. The positive unit cell and the negative unit cell may be separated from each other by a separator.

[0035] In some other embodiments, the plurality of unit cells (111) may consist of a plurality of positive unit cells and a plurality of negative unit cells stacked alternately. The plurality of positive unit cells and the plurality of negative unit cells may be separated from each other by a separator.

[0036] The stacked electrode assembly (110) may have electrode leads (116) at both ends in the second direction (e.g., the Y-axis direction). The electrode leads (116) may be electrically connected to the electrode tabs of the plurality of unit cells (111). One or more electrode tabs may be connected to one electrode lead (116). In some embodiments, two or more electrode tabs may be connected to one electrode lead (116).

[0037] In some embodiments, the stacked electrode assembly (110) may have two electrode leads (116) on one side and two electrode leads (116) on the other side. In this case, half of the plurality of unit cells (111) included in the stacked electrode assembly (110) may be coupled to a first electrode lead on one side and to a second electrode lead on the other side. Also, the remaining half of the plurality of unit cells (111) included in the stacked electrode assembly (110) may be coupled to a third electrode lead on one side and to a fourth electrode lead on the other side. However, the present invention is not limited thereto.

[0038] In some embodiments, the stacked electrode assembly (110) may have one or more electrode leads on one side. In some embodiments, the stacked electrode assembly (110) may have one or more electrode leads on the other side.

[0039] A first MTB (120a) may be provided at one end of the stacked electrode assembly (110) in the second direction (e.g., the Y-axis direction), and a second MTB (120b) may be provided at the other end. One of the first MTB (120a) and the second MTB (120b) may be electrically connected to the cathode side of the stacked electrode assembly (110), and the other may be electrically connected to the anode side of the stacked electrode assembly (110). The second MTB (120b) may have substantially the same configuration as the first MTB (120a), differing only in polarity. The first MTB (120a) will be described below, but a person skilled in the art will be able to understand the configuration of the second MTB (120b) from this.

[0040] The first MTB (120a) may include an MTB housing (122), an electrode terminal portion (124) accommodated within the MTB housing (122), and a bus bar (125) (see FIG. 3) that electrically connects the electrode terminal portion (124) and the electrode lead (116).

[0041] The MTB housing (122) may be made of a material having relatively high rigidity, such as metal, and defines the outer edge of the first MTB (120a). In some embodiments, the MTB housing (122) may be made of aluminum (Al), nickel (Ni), iron (Fe), cobalt (Co), chromium (Cr), manganese (Mn), or an alloy containing one or more of these.

[0042] The MTB housing (122) may include a through hole (122h) that exposes an electrode terminal portion (124) described later. The through hole (122h) may be provided in the MTB housing (122) so that the electrode terminal portion (124) is exposed toward the second direction (e.g., the Y-axis direction). Accordingly, the through hole (122h) may be provided on a plane perpendicular to the second direction (e.g., the Y-axis direction) of the MTB housing (122). Additionally, the through hole (122h) may have an opening that is open in the longitudinal direction of the electrode assembly (110). The shape of the through hole (122h) may be configured to match the outer shape of the portion where the electrode terminal portion (124) is exposed to the outside.

[0043] A person skilled in the art will understand that the first MTB (120a) described above may further include, as needed, a through hole for a venting disc, a through hole for a check valve, and a through hole for an electrolyte inlet, etc.

[0044] The electrode terminal portion (124) is housed within the MTB housing (122) and may be exposed through the through hole (122h). The electrode terminal portion (124) may be made of a metal or metal alloy with low electrical resistance, for example, copper (Cu), aluminum (Al), nickel (Ni), iron (Fe), platinum (Pt), manganese (Mn), or an alloy containing one or more of these.

[0045] In some embodiments, the exposed surface of the electrode terminal portion (124) exposed outward from the MTB housing (122) may be flat. In some embodiments, the exposed surface may have a plane extending perpendicular to the second direction (e.g., the Y-axis direction).

[0046] In some embodiments, an electrically insulating spacer may be provided between the electrode terminal (124) and the MTB housing (122) so that the electrode terminal (124) is electrically insulated from the MTB housing (122).

[0047] In some embodiments, the first MTB (120a) may include a venting disk (126) configured to rupture when the internal pressure of the secondary battery (100) increases excessively, thereby releasing the gas that causes the excessively increased internal pressure. The venting disk (126) is not restored to its original state when it ruptures due to a thermal event occurring inside the secondary battery (100). The venting disk (126) may be any venting disk known in the art and is not particularly limited.

[0048] In some embodiments, the first MTB (120a) may further include a check valve (128). The check valve (128) may be configured to open to discharge internal gas when the internal pressure of the secondary battery (100) becomes higher than a predetermined first pressure, and to close again when the internal pressure is relieved by the discharge of gas, for example, when it becomes lower than the first pressure. The check valve (128) can be restored to its original state after the discharge of internal gas because there is no part that ruptures due to the discharge of gas. The check valve (128) will be described in more detail later.

[0049] In some embodiments, the first MTB (120a) may further include an electrolyte inlet (127) capable of injecting an electrolyte. In some embodiments, the electrolyte inlet (127) may be provided in only one of the first MTB (120a) and the second MTB (120b).

[0050] The electrolyte injected through the above electrolyte injection port (127) may be an electrolyte used for conventional lithium secondary batteries and is not particularly limited.

[0051] A bus bar may be further provided within the first MTB (120a). FIG. 3 is a schematic diagram showing a cross-section of the first MTB (120a) cut by a plane passing through the electrode terminal portion (124) and perpendicular to the third direction (e.g., the Z-axis direction).

[0052] Referring to FIG. 3, the bus bar (125) may be provided to make surface contact with the electrode terminal portion (124). The bus bar (125) may be made of a metal material with low electrical resistance. In some embodiments, the bus bar (125) may be made of copper (Cu), nickel (Ni), aluminum (Al), iron (Fe), cobalt (Co), platinum (Pt), molybdenum (Mo), tin (Sn), palladium (Pd), or an alloy comprising one or more of these.

[0053] The busbar (125) may be configured to make surface contact with the electrode lead (116) of the stacked electrode assembly (110). In some embodiments, the busbar (125) may be joined to the electrode lead (116) by welding. In some embodiments, the busbar (125) may be joined to the electrode lead (116) by a fastener, for example by a rivet.

[0054] In some embodiments, the bus bar (125) may include a planar center portion (125c) extending horizontally in the first direction (e.g., X-axis direction) and an edge portion (125e) extending bent from the center portion (125c). The center portion (125c) may be configured to form a generally U-shaped cross-sectional shape together with the edge portion (125e) and may extend in the third direction (e.g., Z-axis direction). In some embodiments, the edge portion (125e) may have a planar shape extending perpendicularly in the first direction (e.g., X-axis direction).

[0055] The bus bar (125) can make surface contact with the electrode terminal portion (124) at the center portion (125c). The bus bar (125) can make surface contact with the electrode lead (116) at the edge portion (125e).

[0056] In some embodiments, the electrode lead (116) may include a pre-bended portion that is bent at a portion that does not contact the bus bar (125). The pre-bended portion can prevent stress from being concentrated at a specific part of the electrode lead (116) due to an external force applied to the stacked electrode assembly (110), and consequently, safety can be improved.

[0057] Since the secondary battery (100) of the present invention accommodates units having respective functions within the MTB (120a, 120b), such as an electrode terminal (124), a bus bar (125), a venting disc (126), a check valve (128), and an electrolyte injection port (127), the secondary battery itself has a function equivalent to that of a conventional battery module. Therefore, the secondary battery (100) of the present invention can have a high degree of freedom and compatibility, and is advantageous for implementing a cell-to-pack.

[0058] FIG. 4a is a cross-sectional view showing a check valve (128) according to one embodiment of the present invention.

[0059] Referring to FIG. 4a, the check valve may include a conduit portion (1281) extending outward through the MTB housing (122), a valve packing (1282) provided within the conduit portion (1281), and an elastic body (1283) that provides a restoring force to return the valve packing to its original position.

[0060] In some embodiments, the conduit portion (1281) may be in communication with a cell interior space (IS) surrounded by the laminate sheet (130). The cell interior space (IS) may be defined by the laminate sheet (130) and the MTB housing (122).

[0061] In some embodiments, a first stopper (1284) may be provided in the conduit portion (1281) on the side of the cell internal space (IS). In some embodiments, a second stopper (1285) may be further provided in the conduit portion (1281) spaced apart from the first stopper (1284).

[0062] The valve packing (1282) may be provided between the first stopper (1284) and the second stopper (1285). Additionally, the elastic body (1283) may be provided between the valve packing (1282) and the second stopper (1285). The second stopper (1285) may restrict the movement of the elastic body (1283).

[0063] The valve packing (1282) may be configured to move toward the outside of the secondary battery (100) by the pressure of the cell internal space (IS). The outer diameter of the valve packing (1282) is smaller than the inner diameter of the conduit portion (1281), and the side of the valve packing (1282) may not substantially come into contact with the inner surface of the conduit portion (1281).

[0064] The valve packing (1282) can be moved by being pressurized toward the outside of the secondary battery (100) by the pressure in the cell internal space (IS) when the pressure in the cell internal space (IS) exceeds a predetermined pressure, e.g., a first pressure. As the valve packing (1282) is moved toward the outside of the secondary battery (100) by the pressure in the cell internal space (IS), the check valve (128) can be opened. FIG. 4b is a cross-sectional view showing the check valve (128) in an open state.

[0065] Referring to FIG. 4b, the valve packing (1282) moves due to the pressure in the cell internal space (IS), and the elastic body (1283) can be compressed in correspondence with the pressure in the cell internal space (IS). The gas in the cell internal space (IS) can be discharged to the outside of the secondary battery (100) through the elastic body (1283) and passing through the space on the side of the valve packing (1282).

[0066] When the pressure in the internal space (IS) of the cell becomes lower than the predetermined pressure, for example, the first pressure, the valve packing (1282) can return to its original position by the restoring force of the elastic body (1283). By the valve packing (1282) returning to its original position, the check valve (128) can be switched to a closed state.

[0067] In some embodiments, an O-ring (1287) may be provided between the valve packing (1282) and the first catch (1284) for airtightness. In some embodiments, the O-ring (1287) may be fixed to the first catch (1284). In this case, even if the valve packing (1282) is moved, the O-ring (1287) may remain on the first catch (1284), as shown in FIG. 4b.

[0068] In some other embodiments, the O-ring (1287) may be fixed on the side of the valve packing (1282). In this case, when the check valve (128) is in the open state, the O-ring (1287) may move together with the valve packing (1282).

[0069] The valve packing (1282) may have tapered sides (1282s) having a diameter that decreases toward the cell interior space (IS). The O-ring (1287) may contact the valve packing (1282) in particular at the tapered sides (1282s). The tapered sides (1282s) may be closed by making hermetic contact with the O-ring (1287). Alternatively, the tapered sides (1282s) may be open by being spaced apart from the O-ring (1287).

[0070] A waterproof membrane (1288) may be provided at the end of the above conduit section (1281). The waterproof membrane (1288) can prevent moisture, such as water or steam, from penetrating into the cell interior space (IS) through the check valve (128).

[0071] In some embodiments, the waterproof membrane (1288) may include a material that prevents moisture penetration while allowing carbon dioxide (CO2) to pass through relatively more easily. Thus, the waterproof membrane (1288) can smoothly discharge CO2 generated in the cell interior space (IS) to the outside.

[0072] In some embodiments, the waterproof membrane (1288) may comprise two or more laminated thin films. In some embodiments, the waterproof membrane (1288) may comprise a hydrophobic material. Specifically, the waterproof membrane (1288) may comprise a first layer of a porous type and a second layer of a non-porous type. The first layer may comprise a fluorine-based polymer membrane and the second layer may comprise a silicon-based polymer membrane.

[0073] In some embodiments, the waterproof membrane (1288) may comprise a material that selectively permeates CO2 better than nitrogen (N2). For example, the waterproof membrane (1288) may comprise a material having a CO2:N2 permeability ratio of about 4:1 to about 50:1 when measured according to DIN 53536. If the permeation of CO2 is excessively difficult compared to N2, it may be difficult for gas passing through the side of the valve packing (1282) to be smoothly discharged to the outside. If the permeation of CO2 is excessively easy compared to N2, there is a risk that external gas may penetrate into the cell internal space (IS) in the open state. In some embodiments, the CO2:N2 permeation ratio may be about 4:1 to about 50:1, about 5:1 to about 48:1, about 6:1 to about 45:1, about 7:1 to about 43:1, about 8:1 to about 40:1, about 9:1 to about 38:1, about 10:1 to about 35:1, about 11:1 to about 33:1, about 12:1 to about 30:1, about 13:1 to about 28:1, about 14:1 to about 25:1, about 15:1 to about 23:1, about 16:1 to about 20:1, or a value between any two of these ratios.

[0074] The above-mentioned fluorine-based polymer membrane may include a perfluorinated polymer resin such as polytetrafluoroethylene (PTFE). The above-mentioned silicone-based polymer membrane may include a polymer resin such as polydimethylsiloxane (PDMS). However, the present invention is not limited to these.

[0075] Referring again to FIGS. 1a and 2, the venting disc (126) may be configured to rupture and discharge gas from the cell internal space (IS) when the pressure in the cell internal space (IS) increases to a second pressure higher than the first pressure. As previously explained, once the venting disc (126) is opened to discharge gas from the cell internal space (IS), it is not restored to its original state.

[0076] FIG. 5 is a partially exploded perspective view showing the bonding method of a laminate sheet (130) of a secondary battery (100) according to one embodiment of the present invention. FIG. 6 is a partial cross-sectional view of a laminate sheet (130) according to one embodiment of the present invention.

[0077] Referring to FIGS. 5 and 6, the laminate sheet (130) may be configured to wrap around the side of the stacked electrode assembly (110). In some embodiments, the laminate sheet (130) may be attached to the side of the MTB (120a, 120b) to cover at least partially the side of the MTB (120a, 120b). In some embodiments, the laminate sheet (130) may cover the entire side parallel to the second direction (e.g., the Y-axis direction) of the MTB (120a, 120b). In other embodiments, the laminate sheet (130) may cover only a portion of the side parallel to the second direction (e.g., the Y-axis direction) of the MTB (120a, 120b).

[0078] The above laminate sheet (130) may include a flexible metal layer (134), an inner resin layer (132) provided on one side of the metal layer (134), and an outer resin layer (136) provided on the other side of the metal layer (134).

[0079] The metal layer (134) maintains an appropriate thickness and prevents water vapor, oxygen, and other gases from penetrating from the outside to the inside, and prevents leakage of the electrolyte. In some embodiments, the metal layer (134) may include one or more selected from iron (Fe), carbon (C), chromium (Cr), manganese (Mn), nickel (Ni), aluminum (Al), and alloys thereof, but is not limited thereto. When the metal layer (134) is made of a material containing iron, the mechanical strength is increased, and when it is made of an aluminum material, the flexibility is improved; therefore, aluminum metal foil is typically mainly used.

[0080] The metal layer (134) can be configured to have a thickness and mechanical strength such that it can be deformed relatively easily by external force and that no cracks or holes occur even with repeated deformation.

[0081] In some embodiments, the metal layer (134) may have a thickness of about 20 micrometers (μm) to about 100 μm. In some embodiments, the thickness of the metal layer (134) may be about 20 μm to about 100 μm, about 25 μm to about 95 μm, about 30 μm to about 90 μm, about 35 μm to about 85 μm, about 40 μm to about 80 μm, about 45 μm to about 75 μm, about 50 μm to about 70 μm, about 55 μm to about 60 μm, or a range between any two of these figures.

[0082] An inner resin layer (132) provided on one side of the metal layer (134) may include a heat-sealing layer. In some embodiments, the inner resin layer (132) may include a polyolefin-based material capable of performing a sealing action through fusion. In some embodiments, the inner resin layer (132) may include modified propylene, such as casted polypropylene (CPP), or a polypropylene-butylene-ethylene terpolymer.

[0083] The above internal resin layer (132) may be formed by coating or laminating on one side of the metal layer (134).

[0084] The outer resin layer (136) provided on the other side of the metal layer (134) can serve as a base substrate and a protective layer for forming the laminate sheet (130). The outer resin layer (136) may include an insulating material such as polyethylene terephthalate (PET) or nylon.

[0085] In some embodiments, the inner resin layer (132) and the outer resin layer (136) may each have a thickness of about 10 micrometers (μm) to about 50 μm. In some embodiments, the thickness of the inner resin layer (132) and the outer resin layer (136) may each have a range of about 10 μm to about 50 μm, about 12 μm to about 48 μm, about 15 μm to about 45 μm, about 17 μm to about 43 μm, about 20 μm to about 40 μm, about 22 μm to about 38 μm, about 25 μm to about 35 μm, about 27 μm to about 33 μm, or between any two of these values.

[0086] In some embodiments, an adhesive resin layer may be further provided between the inner resin layer (132) and the metal layer (134) and / or between the outer resin layer (136) and the metal layer (134). The adhesive resin layer may be provided for smooth adhesion between dissimilar materials. The adhesive resin layer may be formed as a single layer or multiple layers. In some embodiments, the adhesive resin layer may comprise a polyolefin resin, a polyurethane resin, an epoxy resin, or a mixture thereof.

[0087] In some embodiments, the inner resin layer (132) may be fused to the sides of the MTBs (120a, 120b) at both ends in a second direction (e.g., the Y-axis direction). The stacked electrode assembly (110) may be encapsulated within the secondary battery by the inner resin layer (132) being fused while surrounding the sides of the MTBs (120a, 120b). The inner resin layer (132) may be fused onto the sides by melting by heating and then cooling while in contact with the sides of the MTBs (120a, 120b).

[0088] The laminate sheet (130) can be wrapped around the sides of the MTBs (120a, 120b) and the stacked electrode assembly (110), and then the inner resin layers (132) can be closely attached to each other in the laminated portion (130m) and then the inner resin layers (132) facing each other can be fused together.

[0089] The above-mentioned laminated portion (130m) may be located on any one side of the stacked electrode assembly (110). In some embodiments, the laminated portion (130m) may be located in a third direction (e.g., Z-axis direction) of the stacked electrode assembly (110) after surrounding the stacked electrode assembly (110).

[0090] As explained above, in the secondary battery (100) of the present invention, the stacked electrode assembly (110) is directly surrounded by a laminate sheet (130) without a forming process for the laminate sheet (130), so unit cells can be accommodated with a thickness greater than that defined in the conventional forming process. Therefore, the secondary battery (100) of the present invention is advantageous for realizing a large-capacity cell.

[0091] (2nd Example)

[0092] FIG. 7a is a perspective view showing a main part of a secondary battery (100a) according to another embodiment of the present invention. FIG. 7b is a partial perspective view showing an enlarged portion of the secondary battery (100a) of FIG. 7a. FIG. 8 is a side view of a secondary battery (100a) according to another embodiment of the present invention.

[0093] The above secondary battery (100a) differs from the embodiment described with reference to FIGS. 1a to 5 in that the MTB is provided only on one side of the stacked electrode assembly extending in the second direction (e.g., the Y-axis direction). Therefore, the following description focuses on these differences, and additional explanations regarding overlapping parts are omitted.

[0094] Referring to FIGS. 7a through 8, since the MTB (120c) is provided on only one side rather than both sides of the stacked electrode assembly, both electrodes of the stacked electrode assembly are connected to the MTB (120c). That is, the MTB (120c) is provided only on one side of the second direction (e.g., Y-axis direction) of the stacked electrode assembly, and the laminated portion (130m) can be extended without an MTB on the other side of the second direction (e.g., Y-axis direction) of the stacked electrode assembly.

[0095] Since the MTB is provided on only one side of the stacked electrode assembly, the MTB (120c) is provided with a first electrode terminal portion (124a) and a second electrode terminal portion (124b) of different polarities. One of the first electrode terminal portion (124a) and the second electrode terminal portion (124b) may be a terminal portion corresponding to the cathode and the other may be a terminal portion corresponding to the anode.

[0096] In FIG. 7b, a venting disk (126) is shown between the first electrode terminal (124a) and the second electrode terminal (124b), but the relative positions of the first electrode terminal (124a), the second electrode terminal (124b), and the venting disk (126) within the MTB (120c) are not particularly limited.

[0097] The laminated portion (130m) of the laminate sheet (130) may extend in a second direction (e.g., Y-axis direction) from one side of the third direction (e.g., Z-axis direction) of the stacked electrode assembly (e.g., the upper side in FIG. 8). Furthermore, the laminated portion (130m) may extend in a third direction (e.g., Z-axis direction) from the other side. In FIG. 8, the stacked electrode assembly is surrounded by the laminate sheet (130).

[0098] (3rd Example)

[0099] FIG. 9 is a perspective view showing the main part of a secondary battery (100) according to another embodiment of the present invention.

[0100] Referring to FIG. 9, the secondary battery (100) may further include an external collector (140). The external collector (140) may be configured to collect gas discharged through the check valve (128). The external collector (140) may be connected to the check valve (128) through a gas flow path (142).

[0101] In some embodiments, the external collector (140) may be configured to actively suck in gas discharged from the check valve (128). In this case, the external collector (140) may include a device for applying a predetermined pressure (e.g., a pressure less than the first pressure) to the end of the check valve (128).

[0102] In some embodiments, the external collector (140) may be configured to simply collect the gas discharged from the check valve (128). In this case, the external collector (140) does not actively inhale the gas discharged from the check valve (128).

[0103] When the above external collector (140) is provided, the waterproof membrane (1288) in the check valve (128) may be omitted.

[0104] As described above, although embodiments of the present invention have been described in detail, a person skilled in the art to which the present invention pertains will be able to modify and implement the present invention in various ways without departing from the spirit and scope of the present invention as defined in the appended claims. Therefore, future modifications to the embodiments of the present invention will not depart from the technology of the present invention. Explanation of the symbols

[0105] 100, 100a: Secondary battery 110: Stacked electrode assembly 111: Unit cell 116: Electrode Lead 120a, 120b, 120c: MTB 122: MTB Housing 122h: Penetrating hole 124: Electrode terminal section 125: Busbar 125c: Center section 125e: Edge part 126: Venting Disc 127: Electrolyte inlet 128: Check valve 130: Laminated sheet 130m: Laminated section 132: Internal resin layer 134: Metal layer 136: External resin layer 140: Collector 1281: Daoist Temple 1282: Valve packing 1283: Elastic body 1284: First stopper 1285: Second stop 1287: O-ring 1288: Waterproof membrane

Claims

Claim 1 A secondary battery comprising: a plurality of unit cells stacked in a first direction and having electrode leads at both ends of a second direction perpendicular to the first direction; a multifunctional terminal block (MTB) provided at least one end of the stacked electrode assembly; and a laminate sheet wrapping the side of the stacked electrode assembly to define a cell internal space; wherein the MTB comprises: an electrode terminal portion electrically connected to the electrode leads of the stacked electrode assembly; a check valve configured to discharge gas in the cell internal space exceeding a first pressure; and a rupture disk configured to rupture and discharge gas when the pressure in the cell internal space increases to a second pressure exceeding the first pressure; and wherein the laminate sheet comprises a metal layer, an inner resin layer provided on one side of the metal layer, and an outer resin layer provided on the other side of the metal layer, wherein the inner resin layer is fused while surrounding the side of the MTB, and the laminate sheet is fused such that the inner resin layers face each other at the laminated portion after surrounding the side of the MTB. Claim 2 A secondary battery according to claim 1, characterized in that the check valve is configured to switch from a closed state to an open state when the pressure in the internal space of the cell exceeds the first pressure, and to switch from an open state to a closed state after the pressure in the internal space of the cell is relieved to a level lower than the first pressure. Claim 3 In claim 2, the check valve comprises: a conduit portion communicating with the cell internal space and open to the outside of the secondary battery; a valve packing provided within the conduit portion and capable of moving toward the outside of the secondary battery by the pressure of the cell internal space; and an elastic body that causes the valve packing to return to its original position according to the pressure of the cell internal space. Claim 4 A secondary battery according to claim 3, wherein the conduit portion comprises: a first stopper provided at the end of the cell internal space side; and a second stopper provided on the inner circumference of the conduit portion spaced apart from the first stopper; wherein the valve packing is disposed between the first stopper and the second stopper, and the elastic body is disposed between the valve packing and the second stopper. Claim 5 A secondary battery according to claim 3, wherein the check valve comprises an O-ring provided between the valve packing and the conduit portion, and the valve packing comprises a tapered side having a diameter that decreases toward the internal space of the cell, and the tapered side is configured to form the closed state by making hermetic contact with the O-ring and to form the open state by being spaced apart from the O-ring. Claim 6 A secondary battery according to claim 3, wherein the check valve further comprises a waterproof membrane at the end of the conduit portion. Claim 7 A secondary battery according to claim 6, characterized in that the waterproof membrane comprises a material capable of permeating carbon dioxide. Claim 8 A secondary battery according to claim 6, wherein the waterproof membrane comprises two or more stacked thin films. Claim 9 A secondary battery according to claim 8, wherein the waterproof membrane comprises a first layer of a porous type and a second layer of a non-porous type. Claim 10 A secondary battery according to claim 9, characterized in that the first layer comprises a fluorine-based polymer film and the second layer comprises a silicon-based polymer film. Claim 11 A secondary battery according to claim 3, further comprising an external collector connected to the check valve to communicate with gas and configured to collect gas discharged from the check valve. Claim 12 A secondary battery according to claim 11, characterized in that the end of the conduit portion does not include a waterproof membrane. Claim 13 A secondary battery comprising: a stacked electrode assembly having a plurality of unit cells stacked in a first direction and extending in a second direction perpendicular to the first direction and having an electrode lead at an end; a multifunctional terminal block (MTB) coupled to the electrode lead of the stacked electrode assembly; and a laminate sheet wrapping the stacked electrode assembly together with the MTB to define a cell internal space; wherein the MTB comprises: an electrode terminal portion electrically connected to the electrode lead of the stacked electrode assembly; a busbar electrically connecting the electrode lead and the electrode terminal portion; and a check valve configured to discharge gas in the cell internal space exceeding a first pressure; and wherein the check valve comprises: a conduit portion communicating with the cell internal space and open to the outside of the secondary battery; A secondary battery comprising: a waterproof membrane provided at the outer end of the conduit portion; wherein the laminate sheet comprises a metal layer, an inner resin layer provided on one side of the metal layer, and an outer resin layer provided on the other side of the metal layer, wherein the inner resin layer is fused while surrounding the side of the MTB, and the laminate sheet is fused with the inner resin layers facing each other at the laminated portion after surrounding the side of the MTB. Claim 14 A secondary battery according to claim 13, wherein the waterproof membrane comprises a hydrophobic material. Claim 15 A secondary battery according to claim 13, characterized in that the waterproof membrane has a CO2:N2 permeability ratio of 4:1 to 50:1 when measured according to DIN 53536.

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