Secondary battery

Abstract

A secondary battery according to one embodiment of the present invention comprises: an electrode assembly; an electrode tab having one end electrically connected to at least one electrode in the electrode assembly; a battery case including an accommodation part for accommodating the electrode assembly and the electrode tab; and an electrode lead bonded to the other end of the electrode tab so as to protrude to the outside of the battery case, wherein the battery case further includes a space part which is connected to one end of the electrode lead and which is expanded by gas when the gas is generated inside the battery case, and the electrode tab can be broken by physical force transferred through the electrode lead when the space part is expanded by the gas to a predefined threshold level or more.

Description

secondary battery

[0001] This application claims the benefit of Korean Patent Application No. 10-2024-0067687 filed with the Korean Intellectual Property Office on May 24, 2024, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to a secondary battery, and more particularly, to a secondary battery that improves stability by breaking an electrode tab when gas is generated within the battery.

[0003] Secondary batteries are batteries that can be reused by charging even after discharge, and can be used as an energy source for small devices such as mobile phones, tablet PCs, and vacuum cleaners, and are also used as an energy source for medium and large devices such as automobiles and ESS (Energy Storage Systems) for smart grids.

[0004] One of the major research tasks for these secondary batteries is to improve safety.

[0005] In general, secondary batteries have the potential to explode due to abnormal battery conditions such as internal short circuits, overcharging or overheating, and external shock.

[0006] In particular, secondary batteries used in medium and large battery packs as power sources for electric vehicles, hybrid vehicles, etc. require a long lifespan and, as a result of the characteristics of multiple batteries being provided in close proximity, ensuring safety is very important.

[0007] Therefore, there is a need for technological development to improve the stability of secondary batteries by preventing ignition or explosion of the batteries in advance.

[0008] The purpose of the present invention to solve the above problems is to provide a secondary battery with improved stability.

[0009] According to an embodiment of the present invention for achieving the above object, a secondary battery comprises: an electrode assembly; an electrode tab electrically connected to at least one electrode in the electrode assembly; a battery case including a receiving portion for receiving the electrode assembly and the electrode tab; and an electrode lead joined to the electrode tab and protruding out of the battery case, wherein the battery case further comprises a space portion joined to at least a portion of an area of ​​the electrode lead and expanded by gas when gas is generated inside the battery case; and when the space portion expands by the gas, the electrode tab is broken by a physical force transmitted through the electrode lead.

[0010] Here, the volume of the space portion may be provided in an asymmetrical shape that becomes smaller as it goes down from the first side to the second side.

[0011] In addition, when the space portion expands due to gas, the gas expansion density is concentrated on the first side of the space portion, so that the electrode tab can be broken in a diagonal direction by sequentially applying an external force from one side of the electrode tab to the other side, which is close to the first side of the space portion.

[0012] Here, the electrode tab may include a notch that guides the break.

[0013] Meanwhile, the battery case includes a folding area formed at at least one end and provided in an asymmetrical shape with an area that becomes smaller as it goes down from the first side to the second side, and the folding area may be provided such that at least a portion of the area is folded and recessed into the receiving portion in the initial state.

[0014] At this time, when a gas exceeding a predetermined first threshold level is generated inside the battery case, at least a portion of the folded area can be unfolded outward.

[0015] Meanwhile, when gas is generated inside the battery case at a second critical level or higher than the first critical level, the gas expansion density is concentrated on the first side of the space, so that the electrode tab can be broken in a diagonal direction by sequentially applying an external force from one side of the electrode tab close to the first side of the space to the other side.

[0016] Additionally, the battery case may include a first case positioned at the bottom of the electrode assembly, and a second case positioned at the top of the electrode assembly and facing the first case.

[0017] At this time, the electrode lead connected to the electrode tab can be sealed and joined to the ends of the first case and the second case.

[0018] Meanwhile, the first case and the second case may include a sealing portion that seals the outer surface of the first case and the second case.

[0019] Here, the sealing portion can seal and join at least one area of ​​the first case, the second case, and the electrode lead by at least one of heat and pressure.

[0020] Additionally, the battery case may be provided as a pouch.

[0021] In the secondary battery according to embodiments of the present invention, the risk of battery explosion can be reduced and safety can be improved by breaking the battery tab when internal gas exceeding a critical level is generated by the battery case including an asymmetrically shaped space.

[0022] Figure 1 is an image of a secondary battery according to an embodiment of the present invention.

[0023] Figure 2 is an exploded perspective view of a secondary battery according to one embodiment of the present invention.

[0024] Figure 3 is a cross-sectional view of a secondary battery cut along line B-B' according to Figure 2.

[0025] Figure 4 is a perspective view of an electrode assembly according to an embodiment of the present invention.

[0026] FIG. 5 is a conceptual diagram for explaining the fracture state of an electrode tab over time according to an embodiment of the present invention.

[0027] FIG. 6 is a partial image of a secondary battery, enlarged from area A of FIG. 1, according to one embodiment of the present invention.

[0028] Figure 7 is an exploded perspective view of a secondary battery according to another embodiment of the present invention.

[0029] Figure 8 is a perspective view of a secondary battery in an initial state according to another embodiment of the present invention.

[0030] FIG. 9 is a partial image of a secondary battery, enlarged from area A of FIG. 1, according to another embodiment of the present invention.

[0031] 100: Battery case 200: Electrode assembly

[0032] 110: Case 1 120: Case 2

[0033] 310: Electrode tab 320: Electrode lead

[0034] 400: Receiving area 500: Sealing area

[0035] 600: Space Department

[0036] The present invention is susceptible to various modifications and embodiments. Specific embodiments are illustrated in the drawings and described in detail in the detailed description. However, this is not intended to limit the present invention to specific embodiments, but rather to encompass all modifications, equivalents, and alternatives falling within the spirit and technical scope of the present invention. Throughout the description of each drawing, similar reference numerals have been used to designate similar components.

[0037] Terms such as "first," "second," "A," and "B" may be used to describe various components, but these components should not be limited by these terms. These terms are used solely to distinguish one component from another. For example, without departing from the scope of the present invention, the first component could be referred to as the "second component," and similarly, the second component could also be referred to as the "first component." The term "and / or" includes any combination of multiple related items listed or any one of multiple related items listed.

[0038] When a component is referred to as being "connected" or "connected" to another component, it should be understood that it may be directly connected or connected to that other component, but that there may be other components intervening. Conversely, when a component is referred to as being "directly connected" or "connected" to another component, it should be understood that there are no other components intervening.

[0039] The terminology used in this application is only used to describe specific embodiments and is not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this application, it should be understood that the terms "comprise" or "have" indicate the presence of a feature, number, step, operation, component, part, or combination thereof described in the specification, but do not exclude in advance the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0040] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and will not be interpreted in an idealized or overly formal sense unless explicitly defined herein.

[0041] Hereinafter, various embodiments according to the present invention will be described in detail with reference to the attached drawings.

[0042]

[0043] Figure 1 is an image of a secondary battery according to an embodiment of the present invention.

[0044] A secondary battery according to an embodiment of the present invention may include a battery case (100) and an electrode assembly (200).

[0045] The battery case (100) may include an electrode assembly (200). According to an embodiment, the battery case (100) may be provided in a sealed form with the first case and the second case facing each other, with the electrode assembly (200) interposed therebetween.

[0046] In addition, the battery case (100) may further include an electrolyte solution. At this time, the battery case (100) may further include an injection port for injecting the electrolyte solution into the sealed interior of the first case and the second case.

[0047] The electrode assembly (200) may include a first electrode, a second electrode, and a separator. Here, the first electrode may correspond to an anode, and the second electrode may correspond to a cathode.

[0048] Meanwhile, the first and second electrodes may each have a maintenance portion coated with an active material and a non-coated portion without an active material. In the present invention, the active material of the first electrode and the active material of the second electrode are not limited to specific chemicals.

[0049] The electrode assembly (200) may be provided in a structure in which a first electrode and a second electrode are stacked with a separator interposed therebetween. In other words, the electrode assembly (100) may be provided in a stacked or stacked / folded structure in which a first electrode, a second electrode, and a separator manufactured to a certain area are sequentially stacked. However, without being limited to the disclosed structure, the electrode assembly (200) may also be provided in a rolled structure in which a first electrode, a second electrode, and a separator manufactured to a certain area are sequentially stacked and then rolled up.

[0050] An electrode terminal electrically connected to an electrode assembly (200) may be provided on the outer surface of the battery case (100). Here, the electrode terminal may include a first electrode portion connected to a first electrode, and a second electrode portion connected to a second electrode. The first electrode portion and the second electrode portion will be described in more detail with reference to FIG. 4 below.

[0051]

[0052] FIG. 2 is an exploded perspective view of a secondary battery according to one embodiment of the present invention, and FIG. 3 is a cross-sectional view of the secondary battery cut along line B-B' according to FIG. 2.

[0053] Referring to FIGS. 2 and 3, the battery case (100) may be provided as a thin film formed of a flexible material. For example, the battery case (100) may be manufactured by forming a laminate sheet in which a resin layer and a metal layer (e.g., an aluminum sheet) are laminated and bonded, so as to enable a certain level of shape deformation.

[0054] According to one embodiment, the battery case (100) may include a first case (110) and a second case (120). Here, the first case (110) and the second case (120) may be provided in the same shape. For example, the first case (110) and the second case (120) may be provided as a thin film having a trapezoidal shape.

[0055] To be more specific, the first case (110) can be placed above the electrode assembly (200).

[0056] Additionally, the second case (120) can be placed at the bottom relative to the electrode assembly (200) to correspond to the first case (110).

[0057] The first case (110) may include an electrode assembly (200) and a receiving portion (400) for receiving an electrolyte. In addition, the first case (110) may further include a sealing portion (500) formed along the outer periphery.

[0058] Here, the sealing portion (500) may be configured to seal the electrode assembly (200) and the electrolyte located between the first case (110) and the second case (120). For example, the first case (110) may be heat-sealed and sealed with the second case (120) by heat and pressure applied to the sealing portion (500). Accordingly, the electrolyte located inside the receiving portion (400) may be prevented from leaking to the outside of the battery case (100). However, without being limited to what has been disclosed, the sealing portion (500) may be additionally formed along the outer circumference of the receiving portion (400) as well as the outer periphery of the battery case.

[0059] Meanwhile, according to another embodiment, the battery case (100) may be provided as a single thin film.

[0060] To explain in more detail, the battery case (100) may be provided so that the first region is arranged at the top and the second region is arranged at the bottom based on a horizontal line passing through the center point. In other words, the battery case (100) may be provided so that the electrode assembly (200), the first and second electrode tabs (310-1, 310-2), and a portion of the first and second electrode leads (320-1, 320-2) are wrapped between the first and second regions based on the horizontal line in a “ㄷ” shape. At this time, the electrode tabs (310-1, 310-2) and the electrode leads (320-1, 320-2) may be provided as a single configuration that is combined into one. For example, the first electrode tab (310-1) and the first electrode lead (320-1) may be provided in the form of a first lead tab, and the second electrode tab (310-2) and the second electrode lead (320-2) may be provided in the form of a second lead tab. Thereafter, the battery case (100) may be provided with the open side portions sealed by the sealing portion (500).

[0061]

[0062] Figure 4 is a perspective view of an electrode assembly according to an embodiment of the present invention.

[0063] Referring to FIG. 4, the electrode assembly (200) may be a stacked structure in which a first electrode, a second electrode, and a separator manufactured in the same shape and size of a predetermined size are sequentially stacked.

[0064] The electrode assembly (200) can be connected to a first electrode portion and a second electrode portion formed at each end for electrical connection with an external device.

[0065] The first electrode portion may include a first electrode tab (310-1) and a first electrode lead (320-1). Here, one side of the first electrode tabs (310-1) may be electrically connected to the first electrode lead (320-1), and the other side of the first electrode tabs (310-1) may be electrically connected to each of the first electrode layers of the electrode assembly (200). According to an embodiment, the first electrode lead (320-1) may be welded to the first electrode tabs (310-1).

[0066] The second electrode portion may include a second electrode tab (310-2) and a second electrode lead (320-2). Here, one side of the second electrode tabs (310-2) may be electrically connected to each of the second electrode layers, and the other side of the second electrode tabs (310-2) may be electrically connected to the second electrode lead (320-2). Accordingly, the second electrode lead (320-2) may be welded to the second electrode tabs (310-2) and may extend from the other end of the second electrode tabs (310-2).

[0067] Meanwhile, the first electrode tab (310-1) and the second electrode tab (310-2) may be provided as a metal thin film having a predetermined thickness. According to an embodiment, the first electrode tab (310-1) and the second electrode tab (310-2) may be provided as a metal foil having a thickness of micrometers (㎛). Accordingly, the first electrode tab (310-1) and the second electrode tab (310-2) may be cut in a diagonal direction by a physical force when the space portion (600) within the battery case (100) to be described later expands.

[0068]

[0069] FIG. 5 is a conceptual diagram for explaining the fracture state of an electrode tab over time according to an embodiment of the present invention.

[0070] Referring to FIG. 5, the battery case (100) can accommodate the electrode assembly (200) in a sealed state, as described above.

[0071] In general, gas may be generated inside a secondary battery due to a chemical reaction resulting from charging and discharging of the battery. Accordingly, a space (600) may be formed inside the battery case (100).

[0072] The space portion (600) may be formed in at least one end of the battery case (100). At this time, the space portion (600) may include a first space portion (600A) formed in the first side portion and a second space portion (600B) formed in the second side portion.

[0073] One of the first space portion (600A) and the second space portion (600B) may have a relatively larger volume than the second space portion (600B). In other words, the first space portion (600A) and the second space portion (600B) may be provided in asymmetrical sizes.

[0074] Accordingly, when gas is generated from the electrode assembly (200), a larger amount of gas may exist in the first space (600A) compared to the second space (600B). In other words, the gas expansion density of the first space (600A) may be greater than the gas expansion density of the second space (600B). Accordingly, a rotational force (F) may be applied to the first space (600A) in a counterclockwise direction.

[0075] At this time, when the rotational force (F) becomes greater than the tension of at least one electrode tab (310-1, 310-2), at least one electrode tab (310-1, 310-2) may be sequentially broken (C1→C2) in a diagonal direction (L) from the first side toward the second side.

[0076] The shape of the battery case according to embodiments of the present invention will be described in more detail in FIGS. 6 to 9 below.

[0077]

[0078] FIG. 6 is a partial image of a secondary battery, enlarged from area A of FIG. 1, according to one embodiment of the present invention.

[0079] Referring to FIGS. 2, 5, and 6, a battery case (100) according to one embodiment of the present invention may include a first case (110) and a second case (120) whose cross-sections are asymmetrical vertically with respect to the long axis. In other words, the cross-section sizes of the first case (110) and the second case (120) may gradually increase or decrease from one side to the other. For example, the cross-sections of the first case (100) and the second case (120) may be provided in a trapezoidal shape.

[0080] The first case (110) and the second case (120) have a sealing portion (500) formed on the outer portion, so that they can be sealed with at least one electrode tab (310-1, 310-2) interposed therebetween.

[0081] Thereafter, as shown in FIG. 6, when gas is generated inside the secondary battery, an asymmetrical space (600) may be formed at at least one end of the battery case (100) due to the expansion of the gas.

[0082] Here, the space portion (600) provides an asymmetrical volume, so that the gas density can be relatively concentrated on the first side portion (600A) compared to the second side portion (600B). Accordingly, an external force (F) can be generated on the first side portion (600A). Accordingly, a rotational force (F) can also be applied to at least one electrode tab (310-1, 310-2) that is fixed together by sealing.

[0083] At this time, if the gas expansion density exceeds a predetermined critical level, at least one of the first electrode tab (310-1) and the second electrode tab (310-2) may be fractured in a diagonal direction from the first side (600A) toward the second side (600B). Here, the predetermined critical level may be the gas density immediately before a vent occurs. For example, the predetermined critical level may be calculated in advance by considering the expansion force of the space (600), the tension of the electrode tabs (310-1) and the electrode leads (310-2), the bonding force of the sealing portion (500), etc.

[0084] To explain in more detail according to one embodiment, when the space portion (600) is located at one end of the battery case (100), a rotational force (F) may be generated in a counterclockwise direction at the first side portion (600A) of the one end. Accordingly, as the first electrode lead (320-1) moves by receiving the rotational force (F) in the counterclockwise direction, a rotational force (F) may also be applied in the same direction (counterclockwise direction) to the first electrode tab (310-1) connected to the first electrode lead (320-1).

[0085] At this time, since the first electrode tab (310-1) is provided as a micrometer metal thin film, when the gas expansion density exceeds a predetermined critical level, a force greater than the tension of the first electrode tab (310-1) can be sequentially applied from the first side (600A) to the second side (600B) of the first electrode tab (310-1). Accordingly, the first electrode tab (310-1) can be sequentially broken (C1→C2) in the first diagonal direction (L).

[0086] Meanwhile, according to another embodiment, when the space portion (600) is located at the other end of the battery case (100), a rotational force (F) may be generated in a clockwise direction at the first side portion (600A) of the other end. Accordingly, as the second electrode lead (320-2) moves by receiving the rotational force (F) in the clockwise direction, a rotational force (F) may be applied in the same direction (clockwise direction) to the second electrode tab (310-2) connected to the second electrode lead (320-2).

[0087] At this time, since the second electrode tab (310-2) is provided as a micrometer metal thin film, when the gas expansion density exceeds a predetermined critical level, a force greater than the tension of the second electrode tab (310-2) can be sequentially applied from the first side (600A) of the second electrode tab (310-2) toward the second side (600B). Accordingly, the second electrode tab (310-2) can be sequentially broken in a second diagonal direction. Here, the second diagonal direction can be opposite to the direction of the first electrode tab (310-1). For example, the first diagonal line can be directed downward to the right, and the second diagonal line can be directed downward to the left.

[0088]

[0089] FIG. 7 is an exploded perspective view of a secondary battery according to another embodiment of the present invention, FIG. 8 is a perspective view of a secondary battery in an initial state according to another embodiment of the present invention, and FIG. 9 is a partial image of a secondary battery, an enlarged area A of FIG. 1, according to another embodiment of the present invention.

[0090] Referring to FIGS. 7 and 8, the first case (110) and the second case (120) may include at least one of a first folding area (110A, 120A) and a second folding area (110B, 120B).

[0091] According to an embodiment, a first folding area (110A, 120A) may be formed at one end of the first case (110) and the second case (120), and a second folding area (110B, 120B) may be formed at the other end of the first case (110) and the second case (120).

[0092] Either of the first folding areas (110A, 120A) and the second folding areas (110B, 120B) may be provided in an asymmetrical shape. More specifically, among the first folding areas (110A, 120A) and the second folding areas (110B, 120B), the area of ​​one of the areas facing each other may be provided to be relatively large. For example, the first folding areas (110A, 120A) and the second folding areas (110B, 120B) may be provided in a triangular shape.

[0093] In addition, the first folding areas (110A, 120A) and the second folding areas (110B, 120B) may be provided in a folded and recessed state within the receiving portion (400) along the guide line (G) in the initial state of the secondary battery. Here, the initial state may be defined as a state before gas is generated within the battery case (100).

[0094] Meanwhile, in the initial state of the secondary battery, the shortest edge of the first folding area (110A) in the first case (110) and the shortest edge of the first folding area (120A) in the second case (120) are each sealed with one end of the first electrode lead (320-1) by the sealing portion (500), thereby being connected to the first electrode tab (310-1) through the first electrode lead (320-1).

[0095] In addition, in the initial state of the secondary battery, the shortest edge of the second folding area (110B) in the first case (110) and the shortest edge of the second folding area (120B) in the second case (120) are each sealed with the other end of the second electrode lead (320-2), thereby being connected to the second electrode tab (310-2) through the second electrode lead (320-2).

[0096] Thereafter, when gas is generated within the secondary battery, at least one of the first folding regions (110A, 120A) and the second folding regions (110B, 120B) recessed within the receiving portion (400) may gradually expand outward due to the expansion of the gas. Accordingly, a space (600) may be formed in at least one of the first folding regions (110A, 120A) and the second folding regions (110B, 120B).

[0097] When gas is generated inside the secondary battery, the space (600) can be gradually expanded outward by the volume density of the gas by injecting the gas into at least one of the first folding areas (110A, 120A) and the second folding areas (110B, 120B) recessed inside the receiving area (400).

[0098] At this time, if the gas expansion density inside the battery case (100) exceeds a predetermined first critical level, the sealing portion (500) may be broken. Accordingly, at least one of the first folding regions (110A, 120A) and the second folding regions (110B, 120B) that were recessed inside the receiving portion (400) may be unfolded, as shown in FIG. 9. Here, the predetermined first critical level may be a gas expansion density that takes into account the expansion force of the space portion (600) and the adhesive force of the sealing portion (500).

[0099] Thereafter, as shown in FIG. 5, if gas is continuously generated within the secondary battery, at least one space (600A, 600B) among the first folding regions (110A, 120A) and the second folding regions (110B, 120B) can be continuously expanded by the gas.

[0100] At this time, the gas density may be relatively concentrated on the first side (600A) of the space portion (600) compared to the second side (600B). Accordingly, an external force (F) may be generated on the first side (600A). Accordingly, a rotational force (F) may also be applied to at least one electrode tab (310-1, 310-2) that is fixed together by sealing.

[0101] Additionally, the gas expansion density of the first side (600A) can reach the predefined second critical level earlier than that of the second side (600B).

[0102] At this time, if the gas expansion density exceeds a predefined second critical level, at least one of the first electrode tab (310-1) and the second electrode tab (310-2) may be sequentially broken from the first side (600A) toward the second side (600B). Here, the predefined second critical level may be the gas density immediately before a vent occurs. For example, the predefined second critical level may be calculated in advance by considering the expansion force of the space (600), the tension and bonding force of the electrode tabs (310-1, 310-2) and the electrode leads (320-1, 320-2), etc.

[0103] To explain in more detail according to one embodiment, when the space portion (600) is located at one end of the battery case (100), a rotational force (F) may be generated in a counterclockwise direction at the first side portion (600A) of the one end. Accordingly, as the first electrode lead (320-1) moves by receiving the rotational force (F) in the counterclockwise direction, a rotational force (F) may also be applied in the same direction (counterclockwise direction) to the first electrode tab (310-1) connected to the first electrode lead (320-1).

[0104] At this time, since the first electrode tab (310-1) is provided as a micrometer metal thin film, when the gas expansion density exceeds a predetermined critical level, a force greater than the tension of the first electrode tab (310-1) can be sequentially applied from the first side (600A) to the second side (600B) of the first electrode tab (310-1). Accordingly, the first electrode tab (310-1) can be sequentially broken (C1→C2) in the first diagonal direction (L).

[0105] Meanwhile, according to another embodiment, when the space portion (600) is located at the other end of the battery case (100), a rotational force (F) may be generated in a clockwise direction at the first side portion (600A) of the other end. Accordingly, as the second electrode lead (320-2) moves by receiving the rotational force (F) in the clockwise direction, a rotational force (F) may be applied in the same direction (clockwise direction) to the second electrode tab (310-2) connected to the second electrode lead (320-2).

[0106] At this time, since the second electrode tab (310-2) is provided as a micrometer metal thin film, when the gas expansion density exceeds a predetermined critical level, a force greater than the tension of the second electrode tab (310-2) can be sequentially applied from the first side (600A) of the second electrode tab (310-2) toward the second side (600B). Accordingly, the second electrode tab (310-2) can be sequentially broken in a second diagonal direction. Here, the second diagonal direction can be opposite to the direction of the first electrode tab (310-1). For example, the first diagonal line can be directed downward to the right, and the second diagonal line can be directed downward to the left.

[0107] In summary, the secondary battery according to the second embodiment of the present invention provides a battery case (100) having a foldable structure, thereby allowing the degree of gas generation within the secondary battery to be checked stepwise according to the first threshold level and the second threshold level.

[0108] Meanwhile, the first electrode tab (310-1) and the second electrode tab (310-2) may have a notch formed to facilitate breaking when broken by the space portion (600).

[0109] According to one embodiment, the first electrode tab (310-1) may include a first notch formed along a first diagonal direction (L) on the surface. Accordingly, when an external force is generated in a counterclockwise direction due to expansion of the space portion (600) caused by gas generation, the first electrode tab (310-1) may be broken in the first diagonal direction by the first notch even with a small force.

[0110] Additionally, according to another embodiment, the second electrode tab (310-2) may include a second notch formed along a second diagonal direction on the surface. Accordingly, when an external force is generated in a clockwise direction due to expansion of the space portion (600) caused by gas generation, the second electrode tab (310-2) may be broken in the second diagonal direction by the second notch even with a small force.

[0111]

[0112] Above, the secondary battery according to the present invention has been described. The secondary battery according to the present invention provides an asymmetrical space formed by the expansion of the gas at both ends of the electric case when gas is generated due to a side reaction inside the battery, so that the electrode tabs connected to one area of ​​the space are broken in a diagonal direction by the rotational force applied to the space, thereby preventing the occurrence of ignition or explosion inside the battery due to the gas.

[0113]

[0114] The secondary battery according to the various embodiments of the present invention described above exhibits high structural stability and can be made lightweight, as both end portions have a square cell structure and the central portion has a pouch-shaped cell structure.

[0115] Although the present invention has been described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various modifications and changes may be made to the present invention without departing from the spirit and scope of the present invention as set forth in the claims below.

Claims

1. Electrode assembly; An electrode tab electrically connected to at least one electrode in the electrode assembly; A battery case including a receiving portion that receives the electrode assembly and the electrode tab; and An electrode lead is connected to the electrode tab and protrudes outside the battery case, The above battery case, further comprising a space portion that is joined to at least a portion of the electrode lead and expands by gas when gas is generated inside the battery case; A secondary battery in which the electrode tab is broken by a physical force transmitted through the electrode lead when the above space is expanded by gas.

2. In claim 1, The volume of the above space is, A secondary battery provided in an asymmetrical shape that becomes smaller as it goes from the first side to the second side.

3. In claim 2, The above electrode tab is, When the above space is expanded by gas, the gas expansion density is concentrated on the first side of the above space, A secondary battery that is fractured in a diagonal direction by sequentially applying external force from one side of the electrode tab to the other side near the first side of the above-mentioned space portion.

4. In claim 1, A secondary battery, wherein the electrode tab includes a notch that guides the break.

5. In claim 2, The above battery case, It comprises a folding region formed at least on one end and provided in an asymmetrical shape, the area of ​​which decreases as it goes down from the first side to the second side, The above folding area is, A secondary battery, wherein at least some of the area is folded and provided in the receptacle in the initial state.

6. In claim 5, The above folding area is, A secondary battery, wherein, when a gas exceeding a predetermined first threshold level is generated inside the battery case, at least a portion of the folded and indented area is spread outward.

7. In claim 6, The above electrode tab is, When gas is generated inside the battery case at a second critical level or higher than the first critical level, the gas expansion density is concentrated on the first side of the space, A secondary battery that is fractured in a diagonal direction by sequentially applying external force from one side of the electrode tab to the other side near the first side of the above-mentioned space portion.

8. In claim 1, The above battery case, A first case located at the bottom of the electrode assembly, and A secondary battery comprising a second case positioned on the upper portion of the electrode assembly and positioned facing the first case.

9. In claim 8, The electrode lead connected to the electrode tab, A secondary battery, which is sealed and joined to the ends of the first case and the second case.

10. In claim 8, The above first and second cases are, A secondary battery including a sealing portion that seals the outer surfaces of the first case and the second case.

11. In claim 10, The above sealing part, By at least one of heat and pressure, A secondary battery, wherein at least one area of ​​the first case, the second case, and the electrode lead is sealed and joined.

12. In claim 1, The above battery case is a secondary battery provided in a pouch.

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