Secondary battery

Abstract

The present invention relates to a secondary battery in which, when the amount of gas inside a case increases and the internal pressure increases, the gas inside the case can be absorbed, through an adsorbent accommodated in a gas adsorption structure, to reduce the amount of the gas inside the case and thereby prevent the case and a cap plate from being deformed by the gas. One embodiment of the present invention provides a secondary battery comprising: an electrode assembly including a first electrode plate and a second electrode plate; a case accommodating the electrode assembly and open at one end; a cap plate sealing the one end of the case; and a gas adsorption structure mounted on the lower surface of the cap plate and accommodating a gas adsorbent, wherein the gas adsorbent is surrounded by an inner film, and the inner film can be surrounded by an outer film and a frame.

Description

secondary battery

[0001] The present disclosure relates to a secondary battery.

[0002] Secondary batteries, unlike non-rechargeable primary batteries, are rechargeable and dischargeable. Low-capacity secondary batteries are used in small, portable electronic devices such as smartphones, feature phones, laptops, digital cameras, and camcorders, while large-capacity secondary batteries are widely used as power sources for motor drives and power storage in hybrid and electric vehicles. These secondary batteries include an electrode assembly comprising a positive and negative electrode, a case housing the electrode assembly, and electrode terminals connected to the electrode assembly.

[0003] The above-described information disclosed in the background technology of this invention is only intended to improve understanding of the background of the present invention, and therefore may include information that does not constitute prior art.

[0004] The present invention can prevent deformation of the case and cap plate due to gas by absorbing gas through an adsorbent contained inside a gas adsorption structure when the gas inside the case increases and the internal pressure increases.

[0005] In addition, the present invention can increase the life of a secondary battery by delaying the time at which a safety vent operates due to a gas absorption structure.

[0006] However, the technical problems to be solved by the present invention are not limited to the problems described above, and other problems not mentioned can be clearly understood by those skilled in the art from the description of the invention described below.

[0007] According to one embodiment of the present invention for solving the above technical problem, a secondary battery includes an electrode assembly having a first electrode plate and a second electrode plate, a case having one end open and accommodating the electrode assembly therein, a cap plate sealing one end of the case, and a gas adsorption structure mounted on a lower surface of the cap plate and containing a gas adsorbent, wherein the gas adsorbent is wrapped by an inner film, and the inner film can be wrapped by an outer film and a frame.

[0008] The frame may have a space provided on the inside, including a top plate fixed to the cap plate and a side wall extending from an edge of the top plate toward the electrode assembly.

[0009] The outer membrane can be bonded to the end of the side wall to seal the interior of the frame.

[0010] The frame is installed so as to cross between the side walls, and may further include a central structure that divides the internal space of the frame into an upper region and a lower region.

[0011] The above central structure may have a hole or open area so that the upper area and the lower area can be connected to each other.

[0012] The inner membrane containing the above gas adsorbent can be stored in the upper region of the central structure in the frame.

[0013] The above central structure can be arranged horizontally with the above top plate.

[0014] It is installed on the lower side of the above central structure, and may further include a tip having a pointed end and facing the outer membrane.

[0015] The above tip may be located at the center of the plane of the above central structure.

[0016] The height of the tip may be smaller than the distance from the central structure to the outer membrane.

[0017] The outer membrane may be concavely deformed inwardly of the frame when the internal pressure of the case increases, making it susceptible to damage by the tip.

[0018] The above tip may be made of a ceramic or plastic material that is not corroded by the gas generated inside the case and has rigidity.

[0019] The outer membrane and the central structure can be arranged horizontally to each other.

[0020] The height of the side walls of the above frame may be the same.

[0021] The inner membrane above is permeable to gases and block liquids.

[0022] The above outer membrane may be a membrane that blocks gases and liquids.

[0023] The inner membrane may be a non-woven filter or a breathable film having micropores capable of blocking liquid.

[0024] The above gas adsorbent may include at least one of calcium carbonate, potassium carbonate, and sodium hydroxide.

[0025] The above outer membrane may be in the form of a flat plate.

[0026] The outer membrane may be a polyethylene, polypropylene, or a composite film of polyethylene and polypropylene.

[0027] According to the present invention, when the gas inside the case increases and the internal pressure increases, a secondary battery can be provided that absorbs the gas through an adsorbent contained inside a gas adsorption structure to reduce the gas inside the case, thereby preventing the case and cap plate from being deformed due to the gas.

[0028] According to the present invention, the life of a secondary battery can be increased by delaying the time at which a safety vent operates due to a gas absorption structure.

[0029] According to another aspect of the present invention, a battery pack manufactured using a battery having an improved structure and a vehicle including the same can be provided.

[0030] However, the effects that can be obtained through the present invention are not limited to the effects described above, and other technical effects that are not mentioned can be clearly understood by those skilled in the art from the description of the invention described below.

[0031] The following drawings attached to this specification illustrate preferred embodiments of the present invention, and together with the detailed description of the invention described below, serve to further understand the technical idea of ​​the present invention, and therefore, the present invention should not be interpreted as being limited to matters described in such drawings.

[0032] Figure 1 is a perspective view illustrating a secondary battery according to the present invention.

[0033] Figure 2 is a cross-sectional view taken along line 2-2' of Figure 1.

[0034] Fig. 3 is an enlarged cross-sectional view of the gas adsorption structure in the secondary battery of Fig. 2.

[0035] Fig. 4 is a cross-sectional view showing the gas adsorption structure of Fig. 3 after operation.

[0036] FIGS. 5A and 5B are perspective views illustrating a battery pack including an exemplary secondary battery according to the present invention.

[0037] FIGS. 6A and 6B are perspective and side views illustrating a vehicle including an exemplary battery pack according to the present invention.

[0038] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. Prior to this, terms or words used in this specification and claims should not be interpreted as limited to their typical or dictionary meanings, and should be interpreted with meanings and concepts that conform to the technical spirit of the present invention based on the principle that the inventor can appropriately define the concept of a term to best explain his or her own invention. Therefore, the embodiments described in this specification and the configurations illustrated in the drawings are only some of the most preferred embodiments of the present invention and do not represent all of the technical spirit of the present invention. Therefore, it should be understood that various equivalents and modified examples may exist as substitutes for them at the time of filing this application.

[0039] Additionally, when used herein, the terms "comprise", "include" and / or "comprising", "including" specify the presence of stated features, numbers, steps, operations, elements, elements and / or groups thereof, but do not preclude the presence or addition of one or more other features, numbers, operations, elements, elements and / or groups thereof.

[0040] Additionally, to facilitate understanding of the invention, the attached drawings may not be drawn to scale and some components may be exaggerated in size. Furthermore, identical components may be assigned the same reference numbers in different embodiments.

[0041] The statement that two compared objects are "identical" means "substantially identical." Therefore, "substantially identical" may include deviations considered low in the art, such as deviations of less than 5%. Furthermore, uniformity of a parameter over a given region may imply uniformity on average.

[0042] Although terms like "first" and "second" are used to describe various components, these components are not limited by these terms. These terms are used merely to distinguish one component from another, and unless otherwise specified, a "first" component may also be a "second" component.

[0043] Throughout the specification, unless otherwise specifically stated, each element may be singular or plural.

[0044] Any configuration being placed "on (or under)" or "above (or below)" a component may mean not only that any configuration is placed in contact with the upper surface (or lower surface) of said component, but also that other configurations may intervene between said component and any configuration placed on (or below) said component.

[0045] Additionally, when it is described that a component is "connected," "coupled," or "connected" to another component, it should be understood that the components may be directly connected or connected to one another, but that other components may also be "interposed" between the components, or that each component may be "connected," "coupled," or "connected" through another component. Furthermore, when it is said that a part is electrically coupled to another part, this includes not only cases where they are directly connected, but also cases where they are connected with another element in between.

[0046] When reference is made throughout the specification to "A and / or B," this means A, B, or A and B, unless otherwise stated. In other words, "and / or" includes all or any combination of the listed items. When reference is made to "C through D," this means C or more and D or less, unless otherwise stated.

[0047] The terminology used herein is for the purpose of describing embodiments of the present disclosure and is not intended to be limiting of the present disclosure.

[0048] FIG. 1 is a perspective view illustrating a secondary battery according to the present invention, and FIG. 2 is a cross-sectional view taken along line 2-2' of FIG. 1.

[0049] The secondary battery (100) of the present invention includes an electrode assembly (110), a first collector plate (120), a second collector plate (130), a first terminal (140), a second terminal (150), a case (160), a cap assembly (170), and a gas adsorption structure (180). The secondary battery (100) of the present invention may be referred to as a square secondary battery or battery.

[0050] The electrode assembly (110) may be formed by laminating or winding a first electrode plate, a separator, and a second electrode plate formed in a thin plate shape or film shape. Here, the first electrode plate may operate as a first polarity, for example, an anode, and the second electrode plate may operate as a second polarity, for example, an anode. In some examples, the electrode assembly (110) may have a jelly roll shape in which the first electrode plate, the separator, and the second electrode plate are laminated and then wound.

[0051] The first electrode plate is formed by applying a first electrode active material such as a transition metal oxide to a first electrode current collector formed of a metal foil such as aluminum, and includes a first electrode non-coated portion (111) which is a region where the first active material is not applied. The first electrode non-coated portion (111) provides a path for current flow between the first electrode plate and the outside. The first electrode non-coated portion (111) is formed to protrude toward one side of the electrode assembly (110), and in some cases, a plurality of first electrode non-coated portions may be welded together to form a single first collector tab. The first electrode non-coated portion (111) protrudes toward one side of the electrode assembly (110).

[0052] The second electrode plate is formed by applying a second electrode active material such as graphite or carbon to a first electrode current collector formed of a metal foil such as copper or nickel, and includes a second electrode non-coated portion (112) which is an area where the second active material is not applied. In addition, the second electrode non-coated portion (112) is formed to protrude toward the other side of the electrode assembly (110), and in some cases, a plurality of the second electrode current collector tabs may be welded together to form a single second current collector tab.

[0053] A separator is positioned between the first and second electrode plates to prevent short circuits and facilitate the movement of lithium ions. The separator may be made of polyethylene, polypropylene, or a composite film of polyethylene and polypropylene. However, the material used for the separator does not limit the scope of the present invention.

[0054] In addition, the electrode assembly (110) can be maintained in shape by a separate insulating tape attached to a portion of the outer surface after a plurality of electrode plates (the first electrode plate and the second electrode plate) are stacked or wound together. Thereafter, the insulating tape can be used to enable the non-conductive portions (111, 112) of the electrode assembly (110) to be welded to the collector plates (120, 140) at precise positions, and can be fixed so that the structure of the electrode assembly (110) is maintained even within the final secondary battery (100) structure.

[0055] In addition, the electrode assembly (110) is housed in a case (160) together with an electrolyte. The electrolyte may be composed of a lithium salt such as LiPF6 or LiBF4 in an organic solvent such as EC (ethylene carbonate), PC (propylene carbonate), DEC (diethyl carbonate), EMC (ethyl methyl carbonate), or DMC (dimethyl carbonate). In addition, the electrolyte may be in the form of a liquid, solid, or gel.

[0056] In some examples, a compound capable of reversible intercalation and deintercalation of lithium (a lithiated intercalation compound) may be used as the cathode active material. Specifically, one or more of a composite oxide of lithium and a metal selected from the group consisting of cobalt, manganese, nickel, and combinations thereof may be used.

[0057] The above composite oxide may be a lithium transition metal composite oxide, and specific examples thereof include lithium nickel-based oxide, lithium cobalt-based oxide, lithium manganese-based oxide, lithium iron phosphate-based compound, cobalt-free nickel-manganese-based oxide, or a combination thereof.

[0058] As an example, a compound represented by any one of the following chemical formulas may be used. LiaA1-bXbO2-cDc(0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05); LiaMn2-bXbO4-cDc(0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05); LiaNi1-b-cCobXcO2-αDα(0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); LiaNi1-b-cMnbXcO2-αDα(0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); LiaNibCocL1dGeO2(0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5, 0≤e≤0.1); LiaNiGbO2(0.90≤a≤1.8, 0.001≤b≤0.1); LiaCoGbO2(0.90≤a≤1.8, 0.001≤b≤0.1); LiaMn1-bGbO2 (0.90≤a≤1.8, 0.001≤b≤0.1); LiaMn2GbO4 (0.90≤a≤1.8, 0.001≤b≤0.1); LiaMn1-gGgPO4(0.90≤a≤1.8, 0≤g≤0.5); Li(3-f)Fe2(PO4)3(0≤f≤2); LiaFePO4(0.90≤a≤1.8).

[0059] In the chemical formula, A is Ni, Co, Mn, or a combination thereof; X is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, or a combination thereof; D is O, F, S, P, or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof; and L1 is Mn, Al, or a combination thereof.

[0060] A positive electrode for a lithium secondary battery may include a current collector (e.g., a first substrate) and a positive electrode active material layer formed on the current collector. The positive electrode active material layer includes a positive electrode active material and may further include a binder and / or a conductive material.

[0061] The content of the positive electrode active material may be 90 wt% to 99.5 wt% with respect to 100 wt% of the positive electrode active material layer, and the contents of the binder and conductive material may be 0.5 wt% to 5 wt%, respectively, with respect to 100 wt% of the positive electrode active material layer.

[0062] Aluminum may be used as the current collector, but is not limited thereto.

[0063] The negative electrode active material includes a material capable of reversibly intercalating / deintercalating lithium ions, lithium metal, an alloy of lithium metal, a material capable of doping and dedoping lithium, or a transition metal oxide.

[0064] The material capable of reversibly intercalating / deintercalating the lithium ions may include a carbon-based negative electrode active material, for example, crystalline carbon, amorphous carbon, or a combination thereof. Examples of the crystalline carbon include graphite such as natural graphite or artificial graphite, and examples of the amorphous carbon include soft carbon or hard carbon, mesophase pitch carbide, calcined coke, and the like.

[0065] As the material capable of doping and dedoping the lithium, a Si-based negative electrode active material or a Sn-based negative electrode active material can be used. The Si-based negative electrode active material can be silicon, a silicon-carbon composite, SiOx (0 < x < 2), a Si-based alloy, or a combination thereof.

[0066] The above silicon-carbon composite may be a composite of silicon and amorphous carbon. According to one embodiment, the silicon-carbon composite may be in the form of silicon particles and amorphous carbon coated on the surface of the silicon particles.

[0067] The silicon-carbon composite may further comprise crystalline carbon. For example, the silicon-carbon composite may comprise a core comprising crystalline carbon and silicon particles and an amorphous carbon coating layer positioned on the surface of the core.

[0068] A negative electrode for a lithium secondary battery may include a current collector (e.g., a second substrate) and a negative electrode active material layer formed on the current collector. The negative electrode active material layer includes a negative electrode active material and may further include a binder and / or a conductive material.

[0069] For example, the negative electrode active material layer may include 90 to 99 wt% of the negative electrode active material, 0.5 to 5 wt% of the binder, and 0 to 5 wt% of the conductive material.

[0070] The above binder may be a non-aqueous binder, an aqueous binder, a dry binder, or a combination thereof. When an aqueous binder is used as the negative electrode binder, a cellulose-based compound capable of imparting viscosity may be further included.

[0071] The current collector may be selected from copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, a polymer substrate coated with a conductive metal, and a combination thereof.

[0072] An electrolyte for a lithium secondary battery may include a non-aqueous organic solvent and a lithium salt.

[0073] The above non-aqueous organic solvent acts as a medium through which ions involved in the electrochemical reaction of the battery can move.

[0074] The above non-aqueous organic solvent may be a carbonate-based, ester-based, ether-based, ketone-based, or alcohol-based solvent, an aprotic solvent, or a combination thereof, and may be used alone or in combination of two or more thereof.

[0075] Additionally, when using a carbonate solvent, a mixture of cyclic carbonate and chain carbonate can be used.

[0076] As described above, a lithium secondary battery may have a separator between the positive and negative electrodes. Such a separator may be a multilayer film of polyethylene, polypropylene, polyvinylidene fluoride, or two or more layers thereof.

[0077] The above separator may include a porous substrate and a coating layer comprising an organic material, an inorganic material, or a combination thereof, positioned on one or both sides of the porous substrate.

[0078] The above organic material may include a polyvinylidene fluoride-based antibody or a (meth)acrylic polymer.

[0079] The above inorganic material may include inorganic particles selected from, but not limited to, Al2O3, SiO2, TiO2, SnO2, CeO2, MgO, NiO, CaO, GaO, ZnO, ZrO2, Y2O3, SrTiO3, BaTiO3, Mg(OH)2, boehmite, and combinations thereof.

[0080] The organic and inorganic substances may be mixed and present in one coating layer, or a coating layer including an organic substance and a coating layer including an inorganic substance may be present in a laminated form.

[0081] The first collector plate (120) is formed of a conductive material such as aluminum, and is electrically connected to the first electrode plate by being coupled to the first electrode non-conductive portion (111) protruding from one end of the electrode assembly (110). The first collector plate (120) can be electrically connected to the first electrode non-conductive portion (111) by welding. The first collector plate (120) can include a first electrode connection portion (121) extending vertically along one side of the electrode assembly (110), and a first terminal connection portion (122) interposed between the electrode assembly (110) and the cap assembly (170) and coupled to the first terminal (140).

[0082] The first electrode connecting portion (121) extends vertically along one side of the electrode assembly (110) and may have a roughly plate shape. The first electrode connecting portion (121) may be joined by welding while in contact with the first electrode non-conducting portion (111) of the electrode assembly (110), so as to have the same first polarity as the first electrode non-conducting portion (111). For convenience of explanation, in the following description, the surface of the first electrode connecting portion (121) facing one side of the electrode assembly (110) will be referred to as the inner surface, and the surface facing one side of the case (160) will be referred to as the outer surface.

[0083] The first terminal connection portion (122) may be bent from the upper end of the first electrode connection portion (121) and may be interposed between the cap assembly (170) and the electrode assembly (110). Such a first terminal connection portion (122) may be integral with the first electrode connection portion (121) or may be welded and joined to the upper end of the first electrode connection portion (121) by welding.

[0084] The second collector plate (130) is formed of a conductive material such as nickel, and is electrically connected to the second electrode plate by making contact with the second electrode non-conductive portion (112) protruding from the other end of the electrode assembly (110). The second collector plate (130) includes a second electrode connection portion (131) and a second terminal connection portion (132). Since the shape of the second collector plate (130) is the same as that of the first collector plate (120), a duplicate description will be omitted.

[0085] The first terminal (140) is formed of a conductive material such as aluminum and can be electrically connected to the first collector plate (120). The first terminal (140) includes a first terminal pillar (141) and a first terminal plate (142).

[0086] The first terminal pillar (141) protrudes and extends upwardly by a certain length through the cap plate (171) of the cap assembly (170), and can be electrically connected to the first collector plate (120) at the lower portion of the cap plate (171). In addition, in some examples, the first terminal pillar (141) can protrude and extend upwardly by a certain length of the cap plate (171). The lower portion of the first terminal pillar (141) can be fitted into a hole provided in the first terminal connection portion (122) of the first collector plate (121), and then riveted and / or welded.

[0087] The first terminal plate (142) has a hole, and the upper portion of the first terminal pillar (141) can be joined to the hole and riveted and / or welded. The first terminal plate (142) can be positioned on the upper portion of the cap plate (171). In some examples, the interface between the first terminal pillar (141) exposed upwardly and the first terminal plate (142) can be welded to each other. For example, a laser beam can be provided to the boundary region of the first terminal pillar (141) exposed upwardly and the first terminal plate (142), so that the boundary region can be melted and then cooled to be welded to each other. In some examples, the first terminal pillar (141) and the first terminal plate (142) can be electrically insulated from the cap plate (171).

[0088] The second terminal (150) is formed of a conductive material such as nickel and is electrically connected to the second collector plate (130). The second terminal (150) includes a second terminal pillar (151) and a second terminal plate (152). Since the shape of the second terminal (150) is the same as that of the first terminal (140), a duplicate description will be omitted.

[0089] The case (160) is formed of a conductive metal such as aluminum, an aluminum alloy, or nickel-plated steel, and has a roughly hexahedral shape with an opening formed into which the electrode assembly (110), the first collector plate (120), and the second collector plate (130) can be inserted and seated. A cap plate (171) can be coupled to the opening of the case (160) to seal the case (160). The inner surface of the case (160) is basically insulated to prevent an electrical short circuit from occurring inside.

[0090] A cap assembly (170) can be coupled to an opening of a case (160). The cap assembly (170) can include a cap plate (171), a seal gasket (172), a plug (173), a safety vent (174), an upper connecting member (175), a lower insulating member (176), and a cooling terminal (177). The cap plate (171) can seal the opening (161) of the case (160). The seal gasket (172) is made of an insulating material and is provided between the cap plate (171) and the first terminal pillar (141) of the first terminal (140), and between the cap plate (171) and the second terminal pillar (151) of the second terminal (150), thereby sealing between the first terminal pillar (141) and the second terminal pillar (141), respectively, and the cap plate (171). This seal gasket (172) prevents external moisture from penetrating into the interior of the secondary battery (100) or prevents the electrolyte contained inside the secondary battery (100) from leaking out to the outside.

[0091] The plug (173) seals the electrolyte injection port of the cap plate (171), and the safety vent (174) is installed in the vent hole of the cap plate (171) and may be provided with a notch so that it can be opened at a set pressure.

[0092] The upper coupling member (175) may be provided between the first terminal plate (142) and the second terminal plate (152) and the cap plate (171) on the upper portion of the cap plate (171). In addition, the upper coupling member (175) is in close contact with the cap plate (171). Furthermore, the upper coupling member (175) may also be in close contact with the seal gasket (172). The upper coupling member (175) may insulate between the first terminal plate (142) and the cap plate (171), and between the second terminal plate (152) and the cap plate (171). In some examples, the upper coupling member (175) formed on the first terminal pillar (141) may electrically connect the first terminal plate (142) and the cap plate (171), and thus, the cap plate (171) may have the same polarity as the first terminal (140). In this case, the case (160) may also have the same polarity as the cap plate (171), and electrical short circuit with the electrode assembly (110) is prevented by the insulation treatment inside.

[0093] A lower insulating member (176) may be provided between the cap plate (171) and the first collector plate (120), and between the cap plate (171) and the second collector plate (130), respectively. The lower insulating member (176) may also be in close contact with the seal gasket (172). The lower insulating member (176) may also be interposed between the first terminal connection portion (122) of the first collector plate (120) and the electrode assembly (110), and between the first terminal connection portion (142) of the second collector plate (140) and the electrode assembly (110).

[0094] The lower insulating member (176) may be made of an insulating material and may prevent electrical contact between the cap plate (171) and the first collector plate (120), and between the cap plate (171) and the second collector plate (140). In addition, the lower insulating member (174) may prevent electrical contact between the electrode assembly (110) and the first collector plate (120), and between the electrode assembly (110) and the second collector plate (130).

[0095] The gas adsorption structure (180) may be fixed to the inner surface of the cap plate (171). The gas adsorption structure (180) may be spaced apart from the upper surface of the electrode assembly (110). The gas adsorption structure (180) may be a structure in which a gas adsorbent for absorbing gas generated inside the electrode assembly is accommodated therein. Such a gas adsorption structure (180) may be mounted so as to be spaced apart from the electrolyte inlet of the cap plate (171) and the safety vent (171). Here, the gas adsorption structure (180) is illustrated as being mounted on the cap plate (171), but may be mounted inside a case (160) that does not affect the capacity change of the electrode assembly (110). However, the secondary battery (100) is provided with a gap between the cap plate (171) and the electrode assembly (110) that occurs when the collector plate and terminal are combined on the cap plate (171), so that a decrease in the capacity of the electrode assembly (110) that occurs when the gas absorption structure (180) is attached can be prevented.

[0096] However, the present invention is not limited thereto, and the case may be configured in various shapes, such as circular or pouch-shaped. In addition, the case may be configured of a metal such as aluminum, aluminum alloy, nickel-plated steel, or a laminate film or plastic forming a pouch.

[0097] FIG. 3 is an enlarged cross-sectional view of a gas adsorption structure (180) in a secondary battery illustrated in FIG. 2, and FIG. 4 is a cross-sectional view of a gas adsorption structure (180) when gas is generated inside the case of a secondary battery and the internal pressure increases.

[0098] A gas adsorption structure (180) may include a frame (181) having a space inside and one side open, an inner film (182) that accommodates a gas adsorbent (182a) and is mounted within the frame (181), a tip (183) fixed to the opposite side of the side where the inner film (182) is accommodated within the frame (181), and an outer film (184) bonded to the open side of the frame (181). Such a frame (181) may be made of a plastic material that does not react with an electrolyte.

[0099] The gas adsorption structure (180) may have a gas adsorbent (182a) wrapped by an inner film (182), and the outer side of the inner film (182) may be further wrapped by a frame (181) and an outer film (184).

[0100] The frame (181) may include an upper plate (181a) fixed to the cap plate (171) and a side wall (181b) extending from the edge of the upper plate (181a) toward the electrode assembly (110). The upper surface of the upper plate (181a) may be fixed by being adhered to the inner surface of the cap plate (171) using an adhesive or adhesive tape, etc. The inner surface of the cap plate (171) may be a surface facing the electrode assembly (110). The shape of the upper plate (181a) may be variously changed, such as a circle or a polygon. In addition, the side walls (181b) may have the same height, and a space may be provided on the inner side of the frame (181) by the upper plate (181a) and the side walls (181b). In addition, the frame (181) may further include a central structure (181c) installed to cross between the side walls (181b). A central structure (181c) like this can be spaced downward from the upper plate (181a). In addition, the central structure (181c) can be arranged horizontally with the upper plate (181a). The frame (181) can be formed by integrally forming the upper plate (181a), side walls (181b), and the central structure (181c).

[0101] Here, the central structure (181c) may have a bar or plate shape, but the present invention is not limited to this shape. However, the central structure (181c) structurally separates the upper and lower parts, but may have an open area in at least some areas. For example, the central structure (181c) may have a hole or an open area in at least some areas, so that the upper and lower areas are connected to each other in the internal space of the frame (181).

[0102] The inner membrane (182) may be accommodated between the upper plate (181a) of the frame (181) and the central structure (181c). The central structure (181c) may be a means for fixing the inner membrane (182) within the frame (181). A gas adsorbent may be accommodated within the inner membrane (182). The gas adsorbent may include at least one of calcium carbonate, potassium carbonate, and sodium hydroxide. In addition, the inner membrane (182) may be a membrane that allows gases to pass through but does not allow liquids to pass through. For example, the inner membrane (182) may include at least one of a non-woven filter or a breathable film having micropores capable of blocking liquids. The inner membrane (182) may include polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), and expanded polytetrafluoroethylene (EPTFE).

[0103] The tip (183) may be installed on the lower side of the central structure (181c). The tip (183) may be positioned at the center of the central structure (181c) on a plane, and may have a pointed end. Here, the end of the tip (183) may face the outer membrane (184). The tip (183) may be spaced apart from the outer membrane (184). For example, the height of the tip (183) may be smaller than the distance between the central structure (181c) and the outer membrane (184). The tip (183) may be made of a ceramic or plastic material that is not corroded by the gas generated inside the case (160) and has rigidity.

[0104] The outer membrane (184) can be bonded to an open surface of the frame (181) to seal the inner space of the frame (181). The outer membrane (184) can be mounted on the frame (181) in the form of a flat plate. The outer membrane (184) can be bonded to an end of a side wall (181b) of the frame (181) using an adhesive. The outer membrane (184) can face the lower surface of the central structure (181c). The outer membrane (184) can be arranged horizontally with respect to the central structure (181c), and the distance between them can be the same. In addition, the outer membrane (184) can be spaced apart from the tip (183) mounted on the central structure (181c). The outer membrane (184) can be formed of a membrane that is impermeable to gas and liquid. In addition, the outer membrane (184) can include a polymer compound that is not corroded by an electrolyte. For example, the outer film (184) may be made of a material similar to that of the separator (113). For example, the outer film (184) may be made of polyethylene, polypropylene, or a composite film of polyethylene and polypropylene. In addition, the outer film (184) may be in the form of a thin film capable of being deformed by pressure.

[0105] As illustrated in FIG. 4, as the secondary battery (100) undergoes a charge / discharge cycle, the outer membrane (184) may be concavely deformed toward the inside of the frame (181) due to the pressure inside the case (160) caused by the increase in internal gas. At this time, the outer membrane (184) may be damaged by contact with the end of the tip (183). Here, the tip (183) is located at the center of the central structure (181c), so that it may be easier to contact the deformed outer membrane (184). The outer membrane (184) may be deformed when the internal pressure of the case (120) exceeds the reference pressure.

[0106] When the outer membrane (184) is damaged in this way, gas inside the case (160) can flow into the inside of the frame (181) of the gas adsorption structure (180) through the damaged portion of the outer membrane (184). The gas that flows into the inside of the frame (181) of the gas adsorption structure (180) can pass through the inner membrane (182) through the central structure (181c) and be absorbed by the adsorbent contained inside the inner membrane (182). That is, when the gas inside the case (160) increases and the internal pressure increases, the gas adsorption structure (180) can absorb the gas through the adsorbent and reduce the gas inside the case (160). Such a gas adsorption structure (180) can delay the time when the safety vent (174) operates, thereby increasing the lifespan of the secondary battery (100). In addition, the gas adsorption structure (180) can reduce gas inside the case (160), thereby preventing the case (160) and cap plate (171) from being deformed due to the gas.

[0107] The secondary battery according to the above-described embodiment can be used to manufacture a battery pack.

[0108] FIGS. 5A and 5B are perspective views illustrating a battery pack including an exemplary secondary battery (100) according to the present invention. Referring to FIGS. 5A and 5B, the battery pack (300) may include a plurality of battery modules (200) and a housing (310) for accommodating the plurality of battery modules (200). For example, the housing (310) may include first and second housings (311, 312) that are coupled in a direction facing each other with the plurality of battery modules (200) interposed therebetween. The plurality of battery modules (200) may be electrically connected to each other using a bus bar (251), and the plurality of battery modules (200) may be electrically connected to each other in a series / parallel or series-parallel hybrid manner to obtain a required electrical output. In the drawings, for convenience of illustration, components such as a bus bar, a cooling unit, and an external terminal for electrically connecting battery cells are omitted. In some examples, the battery pack (300) may be mounted on a vehicle. The vehicle may be, for example, an electric vehicle, a hybrid vehicle, or a plug-in hybrid vehicle. The vehicle may include a four-wheeled vehicle or a two-wheeled vehicle.

[0109] Figures 6a and 6b are perspective views and side views illustrating a vehicle (400, 500) including an exemplary battery pack (300) according to the present invention. In Figure 6a, the battery pack (300) may include a battery pack cover (311) (which may correspond to the first housing) which is a part of a vehicle underbody (410) and a pack frame (312) (which may correspond to the second housing) which is disposed at a lower portion of the vehicle underbody (410). The battery pack cover (311) and the pack frame (312) may be formed integrally with the vehicle floor (420). The vehicle underbody (410) separates the interior and exterior of the vehicle, and the pack frame (312) may be disposed at the exterior of the vehicle.

[0110] As illustrated in FIG. 6b, the vehicle (500) may be formed by combining additional components, such as a hood (510) at the front of the vehicle and fenders (520) positioned at the front and rear of the vehicle, respectively, with the vehicle body (400). The vehicle (500) includes a battery pack (300) including a battery pack cover (311) and a pack frame (312), and the battery pack (300) may be combined with the vehicle body component (400).

[0111] The above description is only one embodiment for implementing the secondary battery according to the present invention, and the present invention is not limited to the above-described embodiment, and as claimed in the following claims, it will be understood that the technical spirit of the present invention exists to the extent that various modifications can be implemented by anyone having ordinary skill in the art to which the present invention pertains without departing from the gist of the present invention.

Claims

1. An electrode assembly comprising a first electrode plate and a second electrode plate; A case having one end open and housing the electrode assembly therein; A cap plate sealing one end of the case; and It is mounted on the lower surface of the above cap plate and includes a gas adsorption structure containing a gas adsorbent, A secondary battery in which the above gas adsorbent is surrounded by an inner membrane, and the inner membrane is surrounded by an outer membrane and a frame.

2. In paragraph 1, The above frame has a top plate fixed to the cap plate, A secondary battery having a space provided on the inside, including a side wall extending from the edge of the upper plate toward the electrode assembly.

3. In paragraph 2, A secondary battery in which the outer membrane is bonded to the end of the side wall to seal the interior of the frame.

4. In paragraph 2, A secondary battery further comprising a central structure that is installed so as to cross between the side walls and divides the internal space of the frame into an upper region and a lower region.

5. In paragraph 4, A secondary battery in which the central structure has a hole or open area so that the upper area and the lower area are connected to each other.

6. In paragraph 4, A secondary battery in which the inner membrane containing the above gas absorbent is housed in the upper region of the central structure in the frame.

7. In paragraph 4, The above central structure is a secondary battery arranged horizontally with the above upper plate.

8. In paragraph 4, A secondary battery installed on the lower side of the central structure and further including a tip with a pointed end facing the outer membrane.

9. In paragraph 8, The above tip is a secondary battery located at the center of the plane of the above central structure.

10. In paragraph 8, A secondary battery wherein the height of the tip is smaller than the distance from the central structure to the outer membrane.

11. In paragraph 8, The above outer membrane is deformed concavely inwardly of the frame when the internal pressure of the case increases, and the secondary battery is damaged by the tip.

12. In paragraph 8, The above tip is a secondary battery made of a ceramic or plastic material that is not corroded by the gas generated inside the case and has rigidity.

13. In paragraph 4, A secondary battery in which the outer membrane and the central structure are arranged horizontally to each other.

14. In paragraph 2, A secondary battery having the same height as the side walls of the above frame.

15. In paragraph 1, The above inner membrane is a secondary battery that allows gas to pass through and blocks liquid.

16. In paragraph 1, The above outer membrane is a secondary battery that blocks gases and liquids.

17. In paragraph 1, A secondary battery in which the inner membrane is a non-woven filter or breathable film having micropores capable of blocking liquid.

18. In paragraph 1, A secondary battery comprising the above gas adsorbent at least one of calcium carbonate, potassium carbonate, and sodium hydroxide.

19. In paragraph 1, The above outer membrane is a secondary battery in the form of a flat plate.

20. In paragraph 1, The above outer membrane is a secondary battery which is a composite film of polyethylene, polypropylene, or polyethylene and polypropylene.

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