Rechargeable battery

Abstract

A rechargeable battery according to one embodiment of the present invention comprises: an electrode assembly, which includes an anode, a cathode and a separator; a case, which accommodates the electrode assembly and includes a bottom portion and a sidewall extending from the edge of the bottom portion; a cap assembly, which seals an opening of the case; and a reinforcing member, which is in contact with an outer surface of the sidewall. The strength of the reinforcing member can be greater than that of the side wall.

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, laptop computers, 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 container (e.g., a case such as a pouch or can) for housing the electrode assembly, and electrode terminals connected to the electrode assembly.

[0003] Typically, secondary batteries are manufactured and then used by housing the electrode assembly inside a container, injecting electrolyte, and sealing it.

[0004] One of the primary factors determining the energy capacity of a secondary battery is the amount of active material contained in the active material layers of the positive and negative electrodes. In other words, the thickness and area of ​​the active material layers can affect the capacity of a secondary battery.

[0005] Increasing the amount of active material to increase energy capacity can increase the volume of the electrode assembly, undesirably increasing the size of the secondary battery. Therefore, indefinitely increasing the amount of active material to increase energy capacity is not desirable.

[0006] Moreover, when there is a size limitation on a device including a secondary battery (e.g., an electric vehicle), it may be desirable in terms of energy density (energy capacity per volume) for the secondary battery to accommodate an electrode assembly containing as much active material as possible while maintaining a constant size.

[0007] Various studies are being conducted to increase energy density. To maintain a constant size of the secondary battery compared to the increase in electrode assembly volume, the thickness of the container needs to be reduced. Specifically, the thickness of the container's side walls needs to be reduced.

[0008] However, if the side walls of the container become thinner, there may be stability issues due to damage to the side walls caused by repeated volume expansion and contraction of the electrode assembly during secondary battery charging and discharging. Furthermore, if thermal runaway occurs within the secondary battery cell, the side walls may be damaged, causing thermal propagation to surrounding secondary battery cells.

[0009] 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.

[0010] An object of the present invention is to provide a secondary battery having increased energy capacity relative to its size, i.e., energy density, without decreasing stability.

[0011] 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.

[0012] According to one embodiment of the present invention for solving the above technical problem, a secondary battery comprises an electrode assembly including a negative electrode, a positive electrode, and a separator, a case that accommodates the electrode assembly and includes a bottom portion and a side wall extending from an edge of the bottom portion, a cap assembly that seals an opening of the case, and a reinforcing member that comes into contact with an outer surface of the side wall, wherein the strength of the reinforcing member may be stronger than the strength of the side wall.

[0013] The above reinforcing member can surround and contact the outer peripheral surface of the side wall.

[0014] The material of the above reinforcing member may be metal.

[0015] The material of the above reinforcing member may be either Al (aluminum) 50 series or SUS (stainless steel).

[0016] The above reinforcing member may have a multilayer structure including different metals.

[0017] The secondary battery may further include a beading portion extending from the side wall and recessed toward the inside of the case, the side wall being connected to the bottom portion through a curved portion, the side wall and the curved portion being connected at a first connection point, the beading portion and the side wall being connected at a second connection point, and the reinforcing member being positioned between the first connection point and the second connection point.

[0018] The length of the above reinforcing member may be at least 50% of the length between the first connection point and the second connection point.

[0019] When the length of the reinforcing member is less than 100% of the length between the first connection point and the second connection point, the reinforcing member may be positioned such that the midpoint of the length of the reinforcing member is closer to the first connection point among the first connection point and the second connection point.

[0020] When the length of the reinforcing member is less than 100% of the length between the first connection point and the second connection point, the reinforcing member may be positioned such that the midpoint of the length of the reinforcing member is closer to the second connection point among the first connection point and the second connection point.

[0021] When the length of the reinforcing member is less than 100% of the length between the first connection point and the second connection point, the reinforcing member may be positioned such that the midpoint of the length of the reinforcing member overlaps the midpoint of the length between the first connection point and the second connection point.

[0022] The thickness of the above reinforcing member may be greater than 20% of the thickness of the side wall.

[0023] The above reinforcing member can be adhesively connected to the outer surface of the side wall.

[0024] The above reinforcing member can be in contact with the outer surface of the side wall in a non-adhesive manner.

[0025] An electric vehicle according to another embodiment of the present invention may include any one of the secondary batteries described above.

[0026] According to an embodiment of the present invention, a reinforcing member having a strength stronger than the strength of a case accommodating an electrode assembly can be surrounded by contacting an outer surface of a side wall of the case, thereby increasing the tensile strength and heat resistance of the secondary battery.

[0027] Therefore, even if a thermal runaway phenomenon occurs within a secondary battery, the secondary battery may not be damaged and thus may not affect adjacent secondary batteries. In other words, heat propagation can be prevented in advance.

[0028] However, the effects that can be obtained through the present invention are not limited to the effects described above, and other technical effects not mentioned can be clearly understood by those skilled in the art from the description of the invention described below.

[0029] 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.

[0030] Figure 1 is a perspective view of a secondary battery according to one embodiment of the present invention.

[0031] Figure 2 is a cross-sectional view taken along line II-II of Figure 1.

[0032] FIG. 3a is a drawing showing a state after conducting a thermal diffusion test of a secondary battery according to one embodiment of the present invention.

[0033] Figure 3b is a drawing showing the state after conducting a thermal diffusion test of a secondary battery according to a comparative example.

[0034] FIG. 4 is a drawing for explaining the thickness and length of a reinforcing member according to one embodiment of the present invention.

[0035] FIGS. 5A to 5C are drawings illustrating a reinforcing member according to another embodiment of the present invention.

[0036] FIG. 6a is a drawing illustrating an adhesive reinforcing member according to another embodiment of the present invention.

[0037] FIG. 6b is a drawing illustrating a non-adhesive reinforcing member according to another embodiment of the present invention.

[0038] FIG. 7 is a drawing illustrating a secondary battery including multiple reinforcing members according to another embodiment of the present invention.

[0039] FIGS. 8A to 8C are drawings showing the finished form of a reinforcing member according to an embodiment of the present invention.

[0040] FIG. 9 is a drawing illustrating an electric vehicle including a secondary battery according to one embodiment of the present invention.

[0041] 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, but should be interpreted with meanings and concepts that conform to the technical idea of ​​the present invention based on the principle that the inventor can appropriately define the concept of the term in order to explain his own invention in the best way. Therefore, it should be understood that 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 idea of ​​the present invention, and various equivalents and modifications may exist at the time of filing this application. In addition, when used in this specification, "comprise", "include" and / or "comprising", "including" specify the presence of mentioned shapes, numbers, steps, operations, elements, components and / or groups thereof, and do not exclude the presence or addition of one or more other shapes, numbers, operations, elements, components and / or groups. Additionally, when describing embodiments of the present invention, “may” and “may be” may include “one or more embodiments of the present invention.”

[0042] Additionally, to facilitate understanding of the invention, the attached drawings are not drawn to scale and some components may be exaggerated in size. Furthermore, identical components may be assigned the same reference numbers in different embodiments.

[0043] 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.

[0044] 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.

[0045] Throughout the specification, unless otherwise specifically stated, each element may be singular or plural.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] Fig. 1 is a perspective view of a secondary battery (1000) according to one embodiment of the present invention. Fig. 2 is a cross-sectional view taken along line II-II of Fig. 1.

[0050] Referring to FIGS. 1 and 2, a secondary battery (1000) includes a case (100), an electrode assembly (200), a cap assembly (300), and a reinforcing member (400).

[0051] The case (100) may include a bottom portion (110), a curved portion (120) having a curved shape extending from an edge of the bottom portion (110), and a side wall (130) connected to the curved portion (120) at a first connection point (CP1).

[0052] The case (100) may have a structure in which one end is sealed by the bottom (110) and the other end is open. That is, the case (100) may have an opening at the other end.

[0053] In the present embodiment, the case (100) is configured as a cylindrical container having an internal space, but the shape of the case (100) is not limited thereto. For example, the case (100) may be square or pouch-shaped, and the electrode assembly (200) may also have a corresponding shape. The case (100) may be manufactured from, but is not limited to, cold-rolled steel sheet (SPCE), steel, stainless steel, aluminum, aluminum alloy, or an equivalent thereof.

[0054] The electrode assembly (200) can be accommodated inside the case (100) through an opening of the case (100). The case (100) may further include a beading portion (140) to prevent the electrode assembly (200) from flowing inside the case (100), for example, from flowing in a direction perpendicular to the bottom portion (110) (up and down direction based on FIG. 2). The beading portion (140) may have a shape that is sunken in from the outside of the side wall (130) toward the electrode assembly (200) (inward direction based on FIG. 2). The beading portion (140) may be connected to the side wall (130) at a second connection point (CP2).

[0055] In the process of the beading portion (140) having a sunken shape, the portion of the case (100) for the beading portion (140) may be easily damaged by an external force. To prevent this, the portion may have a thickness thicker than the thickness of the side wall (130) (T2, see FIG. 4). This portion may be processed to be sunken in a direction (inward in FIG. 2) toward the electrode assembly (200) more than the side wall (130) during the manufacturing process of the secondary battery (1000) to form the beading portion (140).

[0056] A cap assembly (300) for sealing the opening of the case (100) may be placed on the opening side of the case (100). The case (100) may further include a crimping portion (150) to further strengthen the sealing of the opening through the cap assembly (300). The crimping portion (150) may have a shape in which a portion of the case (100) is bent in a direction facing the cap assembly (300).

[0057] The reinforcing member (400) can surround the side wall (130) of the case (100). The reinforcing member (400) can surround the side wall (130) while being in contact with the outer surface or outer circumference surface of the side wall (130). The reinforcing member (400) can prevent damage to the side surface of the secondary battery (1000), that is, the side wall (130) of the case (100), due to expansion of the electrode assembly (200) that occurs during charging and discharging of the secondary battery (1000).

[0058] The reinforcing member (400) may be composed of a material having a strength greater than that of the side wall (130). Even if the side wall (130) is partially damaged due to repeated expansion of the electrode assembly (200) during charging and discharging of the secondary battery (1000), the reinforcing member (400) is not damaged and can withstand the expansion force of the electrode assembly (200).

[0059] In addition, the heat resistance strength of the secondary battery (1000) can be increased by surrounding the side wall (130) with the reinforcing member (400). That is, the reinforcing member (400) can prevent heat diffusion to an adjacent secondary battery (1000) by preventing damage to the side wall (130) when a thermal runaway event occurs inside the secondary battery (1000).

[0060] The material of the reinforcing member (400) may be a metal series. For example, the material of the reinforcing member (400) may be aluminum (Al) 50 series or SUS (stainless steel). However, the present invention is not limited thereto, and any material having a stronger strength than the side wall (130) may be used without limitation.

[0061] The electrode assembly (200) includes a first electrode (210), a second electrode (230), and a separator (250). The separator (250) may be disposed between the first electrode (210) and the second electrode (230). That is, the separator (250) may be interposed between the first electrode (210) and the second electrode (230). The electrode assembly (200) may have a wound shape in which the first electrode (210), the separator (250), and the second electrode (230) are stacked.

[0062] The first electrode (210) may be either an anode or a cathode, and the second electrode (230) may be either an anode or a cathode. For example, if the first electrode (210) is a cathode, the second electrode (230) may be an anode, and if the first electrode (210) is an anode, the second electrode (230) may be a cathode. In this embodiment, it is assumed that the first electrode (210) is a cathode and the second electrode (230) is an anode.

[0063] The negative electrode has a structure in which a negative electrode active material (e.g., graphite, carbon, etc.) is coated on a negative electrode current collector, and the positive electrode has a structure in which a positive electrode active material (e.g., transition metal oxide LiCoO2, LiNiO2, LiMn2O4, etc.) is coated on a positive electrode current collector. The negative electrode current collector may be made of copper (Cu) foil, and the positive electrode current collector may be made of aluminum (Al) foil.

[0064] A separator (250) can be placed between the cathode and the anode to prevent short-circuiting and only allow the movement of ions. The separator (250) can be made of polyethylene (PE) or polypropylene (PP).

[0065] The electrode assembly (200) may further include a first electrode tab (220) and a second electrode tab (240). The first electrode tab (220) may be electrically connected to the first electrode (210). The second electrode tab (240) may be electrically connected to the second electrode (230).

[0066] An insulating tape (not shown) may be placed at the connection boundary between the first electrode tab (220) and the first electrode (210) to prevent a short circuit between the two. Similarly, an insulating tape (not shown) may also be placed at the connection boundary between the second electrode tab (240) and the second electrode (230).

[0067] The first electrode tab (220) may protrude from the first electrode (210) in a direction toward the bottom (110) of the case (100) (downward direction based on FIG. 2) and be coupled to the bottom (110). At this time, the coupling method may be by welding, but is not limited thereto, and includes all methods that can electrically connect the first electrode (210) and the bottom (110).

[0068] When the first electrode tab (220) is combined with the bottom portion (110), the case (100) may have a negative polarity in the present embodiment. Accordingly, the bottom portion (110) may be used as a negative terminal of the secondary battery (1000) according to the embodiment of the present invention.

[0069] The second electrode tab (240) can protrude from the second electrode (230) in a direction toward the cap assembly (300) (upward in FIG. 2) and be electrically connected to the cap assembly (300).

[0070] The first electrode tab (220) may be made of copper (Cu) or nickel (Ni), and the second electrode tab (240) may be made of aluminum (Al).

[0071] The secondary battery (1000) may further include a first insulating member (510) and a second insulating member (530). The first insulating member (510) and the second insulating member (530) may each have a shape of a disc.

[0072] A first insulating member (510) may be disposed between the electrode assembly (200) and the bottom portion (110) of the case (100) to prevent the electrode assembly (200) from electrically contacting the bottom portion (110). The first insulating member (510) may have a first through hole (511) disposed in the center and a second through hole (513) disposed around the first through hole (511).

[0073] The first insulating member (510) has a first through hole (511), so that when a large amount of gas is generated inside the secondary battery (1000), the gas can induce a flow of gas so that the gas moves in a direction (upward in FIG. 2) toward the cap assembly (300) through the center pin (600) described later. In addition, the first insulating member (510) can allow the first electrode tab (220) to penetrate the first insulating member (510) through the second through hole (513) and be electrically connected to the bottom portion (110).

[0074] A second insulating member (530) may be disposed between the electrode assembly (200) and the cap assembly (300) to prevent the electrode assembly (200) from electrically contacting the cap assembly (300). The second insulating member (530) may have a third through hole (531) disposed in the center and a plurality of fourth through holes (533) disposed around the third through hole (531).

[0075] The second insulating member (530) can induce a flow of gas so that a large amount of gas generated inside the secondary battery (1000) moves toward the cap assembly (300) through the third through hole (531). In addition, the second insulating member (530) can allow the second electrode tab (240) to be electrically connected to the cap assembly (300) by penetrating the second insulating member (530) through any one of the plurality of fourth through holes (533). When the electrolyte is injected into the secondary battery (1000) through the remaining fourth through holes (533), the electrolyte can be allowed to permeate more quickly into the electrode assembly (200).

[0076] The secondary battery (1000) may further include a center pin (600) coupled to the central portion of the winding of the electrode assembly (200). The center pin (600) may have the shape of a hollow circular pipe. The center pin (600) may suppress deformation of the electrode assembly (200) that may occur during charging and discharging of the secondary battery (1000), and may serve as a passage for gas generated inside the secondary battery (1000).

[0077] The cap assembly (300) may be positioned between the beading portion (140) and the crimping portion (150). The cap assembly (300) may include a safety vent (310), an insulating plate (320), and a cap up (330).

[0078] The safety vent (310) can be electrically connected to the second electrode tab (240). When the pressure inside the secondary battery (1000) rises above the reference pressure, the safety vent (310) can be deformed or ruptured to release gas generated inside the secondary battery (1000) to the outside and block current flowing inside the secondary battery (1000).

[0079] An insulating plate (320) may be placed between the safety vent (310) and the cap up (330) to block the electrical connection between the safety vent (310) and the cap up (330). The cap up (330) may be placed on the insulating plate (320) so as to be exposed to the outside, and may be used as a second electrode terminal (e.g., a positive terminal) of the secondary battery (1000).

[0080] FIG. 3a is a diagram illustrating a state after a thermal diffusion test of a secondary battery (1000) according to one embodiment of the present invention. FIG. 3b is a diagram illustrating a state after a thermal diffusion test of a secondary battery according to a comparative example.

[0081] The heat diffusion test, also known as the passive propagation resistance (PPR) test, involves artificially applying heat to a specific area of ​​a secondary battery to determine whether a thermal runaway event within the battery causes damage to the sidewall of the case.

[0082] Thermal diffusion testing can be performed on secondary battery cells, modules, or packs. Thermal diffusion testing can be performed sequentially or in parallel on secondary battery cells, modules, and packs.

[0083] The secondary battery according to the comparative example is a secondary battery in which only the reinforcing member (400) is removed from the secondary battery (1000) according to one embodiment of the present invention. That is, the secondary battery according to the comparative example has the same structure and configuration as the secondary battery (1000) according to one embodiment of the present invention, except for the reinforcing member (400).

[0084] Referring to FIG. 3a, a secondary battery (1000) according to one embodiment of the present invention is shown in which the electrode assembly (200) is pulled out only in the direction (upward direction based on FIG. 3a) toward the cap assembly (300) through the safety vent (310) without damage to the side surface, that is, without damage to the side wall of the case.

[0085] Referring to Fig. 3b, the secondary battery according to the comparative example shows a damaged side, i.e., a side wall of the case. It can be confirmed that the extent of damage to the side is at least 50% of the side length. The side length may be the distance between the point where the beading portion and the side wall connect and the point where the side wall and the curved portion connect.

[0086] Considering the above test results, it can be seen that the secondary battery (1000) according to one embodiment of the present invention has its tensile strength and heat resistance reinforced at the side of the secondary battery (1000) through the reinforcing member (400). Accordingly, the secondary battery (1000) according to one embodiment of the present invention can prevent its side from being damaged even in a thermal runaway situation, and further prevent it from affecting adjacent secondary batteries.

[0087] FIG. 4 is a drawing for explaining the thickness (T1) and length (L1) of the reinforcing member (400). Referring to FIG. 4, the reinforcing member (400) may be positioned between the beading portion (140) and the bottom portion (110). Specifically, the reinforcing member (400) may be positioned between the first connection point (CP1) where the beading portion (140) and the side wall (130) are connected, and the second connection point (CP2) where the curved portion (120) and the side wall (130) are connected.

[0088] The length (L1) of the reinforcing member (400) may be 50% or more of the length (L2) between the first connection point (CP1) and the second connection point (CP2).

[0089] If the length (L1) of the reinforcing member (400) is longer than the length (L2) between the first connection point (CP1) and the second connection point (CP2), the increase in the effect of reinforcing the strength of the secondary battery (1000) may be minimal compared to the case where the length (L1) of the reinforcing member (400) is equal to the length (L2) between the first connection point (CP1) and the second connection point (CP2). Accordingly, the length (L1) of the reinforcing member (400) may be shorter than or equal to the length (L2) between the first connection point (CP1) and the second connection point (CP2).

[0090] As described above, the energy capacity of the secondary battery (1000) is affected by the amount of active material. Therefore, reducing the size of the secondary battery (1000) while maintaining the amount of active material may be advantageous in terms of the energy density of the secondary battery (1000).

[0091] The size of the secondary battery (1000) may be influenced by the volume of the case (100) and the thickness (T1) of the reinforcing member (400). If the thickness (T1) of the reinforcing member (400) is set too thick, it may be advantageous in terms of strength reinforcement, but may be disadvantageous in terms of energy density. Therefore, it is necessary to set the thickness (T1) of the reinforcing member (400) so as to harmoniously achieve the two effects mentioned above.

[0092] Table 1 shows the results of a heat diffusion test (PPR) conducted while keeping the thickness (T2) of the side wall (130) fixed and varying only the thickness (T1) of the reinforcing member (400). Examples 1 to 4 are examples in which a heat diffusion test was conducted after setting the thickness (T1) of the reinforcing member (400) to 20%, 40%, 60%, and 80% of the thickness (T2) of the side wall (130), respectively.

[0093] Side wall thickness (mm) Reinforcement member thickness (mm) Thickness ratio (%) Note Example 10.250.0520 PPR test failed Example 20.250.1040 PPR test passed Example 30.250.1560 PPR test passed Example 40.250.2080 PPR test passed

[0094] Referring to Table 1, it can be confirmed that Example 1 fails the heat diffusion test. That is, even though the side wall (130) is wrapped with a reinforcing member (400), it can be seen that both the side wall (130) and the reinforcing member (400) are damaged due to the temperature rise and pressure caused by thermal runaway inside the secondary battery (1000) being unable to withstand it.

[0095] It can be confirmed that Examples 2 to 4 pass the heat diffusion test. That is, it can be seen that the reinforcing member (400) can withstand the temperature rise and pressure caused by thermal runaway inside the secondary battery (1000) only when its thickness (T1) exceeds at least 20% of the thickness of the side wall (130).

[0096] However, in the case of Example 4, the thickness (T1) of the reinforcing member (400) is thicker than in Example 2 or Example 3, so the size of the secondary battery (1000) can be increased.

[0097] Accordingly, the thickness (T1) of the reinforcing member (400) may be thinner than the thickness (T2) of the side wall (130), and when the thickness (T1) of the reinforcing member (400) is greater than 20% and less than 80% of the thickness (T2) of the side wall (130), it can be seen that it is a significant thickness that can achieve both the effect of reinforcing the strength of the secondary battery (1000) and the effect of maintaining or increasing the energy density.

[0098] FIGS. 5A to 5C are drawings for explaining the arrangement position of the reinforcing member (400). Referring to FIG. 5A, when the length (L1) of the reinforcing member (400) is less than 100% of the length (L2) between the first connection point (CP1) and the second connection point (CP2), the reinforcing member (400) can be arranged at a position (upper side based on FIG. 5A) where the length midpoint (ML1) of the reinforcing member (400) is close to the first connection point (CP1).

[0099] Referring to FIG. 5b, when the length (L1) of the reinforcing member (400) is less than 100% of the length (L2) between the first connection point (CP1) and the second connection point (CP2), the reinforcing member (400) can be placed at a position (lower side based on FIG. 5b) where the length midpoint (ML1) of the reinforcing member (400) is close to the second connection point (CP2).

[0100] Referring to FIG. 5c, when the length (L1) of the reinforcing member (400) is less than 100% of the length (L2) between the first connection point (CP1) and the second connection point (CP2), the reinforcing member (400) can be arranged so that the length midpoint (ML1) of the reinforcing member (400) overlaps the midpoint between the first connection point (CP1) and the second connection point (CP2).

[0101] Figures 6a and 6b are drawings for explaining the types of reinforcing members (400). Figure 6a illustrates an adhesive reinforcing member (400'), and Figure 6b illustrates a non-adhesive reinforcing member (400'').

[0102] The adhesive reinforcing member (400') may include a first layer (410') made of a material stronger than the strength of the side wall (130) and an adhesive layer (411') made of an adhesive material for bonding to the side wall (130).

[0103] Non-adhesive means any method by which two components can be joined except for adhesive methods, and the non-adhesive reinforcing member (400'') may have a cylindrical shape. The non-adhesive reinforcing member (400'') may be joined to the side wall (130) of the case (100) by inserting the case (100) into the reinforcing member (400'') that has been made to have a pipe shape in advance, and then applying pressure to bring the two into close contact.

[0104] FIG. 7 is a drawing illustrating a secondary battery (1000''') including multiple reinforcing members (400''') according to another embodiment of the present invention. The multiple reinforcing members (400''') may be formed by forming layers of materials of different materials. For example, the multiple reinforcing members (400''') may be formed by forming two layers of different metal materials.

[0105] The multiple reinforcing members (400''') may include a first layer (410''') and a second layer (420'''). The strength of the first layer (410''') and / or the second layer (420''') may be greater than the strength of the side walls.

[0106] In this embodiment, the multiple reinforcing members (400''') are described as including only two layers (410''', 420'''), but this is not limited thereto, and the multiple reinforcing members (400''') may be formed by two or more materials forming three or more layers.

[0107] Figures 8a to 8c are drawings illustrating the finished form of the reinforcing member (400). Figure 8a is a plan view and a front view of the reinforcing member (400) in a state where the winding start portion (430a) does not contact the winding end portion (430b). Referring to Figure 8a, when the winding start portion (430a) and the winding end portion (430b) do not contact each other, even if the electrode assembly (200) expands, there is room in the gap between the winding start portion (430a) and the winding end portion (430b), so that the tolerance can be more easily compensated.

[0108] Figure 8b is a plan view and a front view of the reinforcing member (400) in a state where the winding start portion (430a) is in contact with the winding end portion (430b). Referring to Figure 8b, when the winding start portion (430a) and the winding end portion (430b) are in contact with each other, the reinforcing member (400) can seamlessly reinforce the strength of the side surface of the secondary battery (1000).

[0109] Figure 8c is a plan view and a front view of a state in which the winding start portion (430a) of the reinforcing member (400) is finished so as to extend beyond the winding end portion (430b). Referring to Figure 8c, when the winding start portion (430a) is finished so as to extend beyond the winding end portion (430b), the reinforcing member (400) can more strongly reinforce the strength of the side surface of the secondary battery (1000).

[0110] Meanwhile, the reinforcing member (400) may be wrapped so as to only contact a portion of the outer surface of the side wall (130), and the wrapping location is not limited to a specific location. That is, the reinforcing member (400) may surround a portion, including a portion where damage is likely to occur during charging and discharging of the secondary battery (1000) or during a heat diffusion test.

[0111] Accordingly, the secondary battery (1000) according to one embodiment of the present invention can efficiently reinforce the strength (tensile strength and heat resistance) of the side surface of the secondary battery (1000) by selectively surrounding the side wall (130) with a reinforcing member (400).

[0112] FIG. 9 is a drawing illustrating an electric vehicle (10) including a secondary battery (1000) according to one embodiment of the present invention. Referring to FIG. 9, the electric vehicle (10) may include a secondary battery (1000) according to one embodiment of the present invention.

[0113] Although the present invention has been described above with reference to limited embodiments and drawings, the present invention is not limited thereto, and it is obvious that various modifications and variations are possible within the scope of the technical idea of ​​the present invention and the equivalent scope of the patent claims to be described below by a person having ordinary skill in the art to which the present invention pertains.

[0114] -Explanation of the symbol-

[0115] 10: Electric vehicles

[0116] 100: Case

[0117] 110: Bottom

[0118] 120: Side wall

[0119] 130: Bidding Department

[0120] 400: Reinforcement member

[0121] 430a: Beginning of the winding

[0122] 430b: End of the winding

[0123] 400': Adhesive reinforcing member

[0124] 400'': Non-adhesive reinforcing member

[0125] 400''': Multiple reinforcing elements

[0126] 410': 1st floor

[0127] 411': Adhesive layer

[0128] 410''': 1st floor

[0129] 420''': 2nd floor

[0130] 1000: Secondary battery

Claims

1. An electrode assembly including a cathode, an anode, and a separator; A case accommodating the electrode assembly and including a bottom portion and side walls extending from an edge of the bottom portion; A cap assembly sealing the opening of the case; and Reinforcing member in contact with the outer surface of the above side wall Including, A secondary battery in which the strength of the above reinforcing member is stronger than the strength of the side wall.

2. In paragraph 1, The above reinforcing member is a secondary battery that surrounds and contacts the outer peripheral surface of the side wall.

3. In paragraph 1, The material of the above reinforcing member is a secondary battery made of metal.

4. In paragraph 3, A secondary battery in which the material of the above reinforcing member is either Al (aluminum) 50 series or SUS (stainless steel).

5. In paragraph 3, The above reinforcing member is a secondary battery having a multilayer structure containing different metals.

6. In paragraph 1, A beading portion extending from the side wall and recessed toward the inside of the case Including more, The above side wall is connected to the above bottom part through a curved portion, The above side wall and the above curved portion are connected at a first connection point, The above beading portion and the side wall are connected at a second connection point, The above reinforcing member is a secondary battery located between the first connection point and the second connection point.

7. In paragraph 6, A secondary battery wherein the length of the reinforcing member is at least 50% of the length between the first connection point and the second connection point.

8. In paragraph 7, A secondary battery in which the length of the reinforcing member is less than 100% of the length between the first connection point and the second connection point, and the reinforcing member is positioned such that the midpoint of the length of the reinforcing member is closer to the first connection point among the first connection point and the second connection point.

9. In paragraph 7, A secondary battery in which the length of the reinforcing member is less than 100% of the length between the first connection point and the second connection point, and the reinforcing member is positioned such that the midpoint of the length of the reinforcing member is closer to the second connection point among the first connection point and the second connection point.

10. In paragraph 7, A secondary battery in which the length of the reinforcing member is less than 100% of the length between the first connection point and the second connection point, and the reinforcing member is positioned such that the length midpoint of the reinforcing member overlaps the length midpoint between the first connection point and the second connection point.

11. In paragraph 1, A secondary battery wherein the thickness of the reinforcing member is greater than 20% of the thickness of the side wall.

12. In paragraph 1, The above reinforcing member is a secondary battery that is in adhesive contact with the outer surface of the side wall.

13. In paragraph 1, The above reinforcing member is a secondary battery that is in contact with the outer surface of the side wall in a non-adhesive manner.

14. A secondary battery according to any one of the preceding clauses. Electric vehicles including.

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