Lead assembly, electrode assembly, and secondary battery comprising same

Abstract

A secondary battery according to the present invention comprises: a battery case; electrodes accommodated in the battery case, each electrode comprising an electrode body and electrode tabs bent and extending from the electrode body; a first electrode lead coupled to the electrode tabs; a second electrode lead coupled to the first electrode lead on a side opposite to a side on which the first electrode lead faces the electrode tabs, and extending to the outside of the battery case; and a coating member covering at least a portion of an end of the second electrode lead.

Description

Lead assembly, electrode assembly, and secondary battery including the same

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority based on Korean Patent Application No. 10-2024-0175576 ​​filed on November 29, 2024, and all contents disclosed in the document of said Korean Patent Application are incorporated herein as part of this specification.

[0003] Technology field

[0004] The present invention relates to a lead assembly, an electrode assembly, and a secondary battery including the same. More specifically, the invention relates to a lead assembly, an electrode assembly, and a secondary battery including the same, which are provided to prevent damage to a battery case.

[0005] A secondary battery configured to generate electricity is provided with an electrode assembly housed within a battery case. In this case, the electrode assembly is formed by stacking a plurality of electrodes and a plurality of separators alternately. The electrode may include an electrode body in which an active material directly involved in generating electricity is located, and an electrode tab extending from the electrode body to transfer the generated electricity to the outside.

[0006] A plurality of electrode tabs, each of a plurality of electrodes, can be joined together as one by welding or the like and connected to an electrode lead. The electrode lead can extend from the inside to the outside of the battery case. Accordingly, generated electricity can be transferred from the electrode tabs to the electrode lead. The electrode lead is connected to the outside of the secondary battery and can serve as a channel to transmit electricity to components that require electricity.

[0007] In this case, the edge or end of the electrode lead may be sharply formed, which can damage the inner wall of the battery case. Since the inner wall of the battery case is coated with plastic material, if this plastic coating is peeled off and damaged by the edge of the electrode lead, a problem of electrical leakage may occur through the damaged part of the battery case.

[0008] In particular, when the electrode tab is bent to minimize dead space, a part of the electrode lead faces the inner wall of the battery case, and consequently, there is a higher possibility that the edge of the electrode lead facing the inner wall of the battery case may damage the inner wall of the battery case.

[0009] The aforementioned background technology is one that the inventor possessed or acquired in the process of deriving the contents of the disclosure of the present application, and it cannot be considered as prior art disclosed to the general public prior to the filing of this application.

[0010] The present invention has been devised to solve the above-mentioned problems, and the objective of the present invention is to provide a lead assembly, an electrode assembly, and a secondary battery including the same that prevent damage to the inner wall of a battery case.

[0011] The technical problems to be solved in this document are not limited to those mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art to which this disclosure belongs from the description below.

[0012] A secondary battery according to one embodiment of the present invention comprises a battery case, an electrode accommodated in the battery case, the electrode including an electrode body and an electrode tab bent and extended from the electrode body, a first electrode lead coupled to the electrode tab, a second electrode lead coupled to the first electrode lead on the opposite side toward the first electrode lead toward the electrode tab and extending outward from the battery case, and a coating member covering at least a portion of the end of the second electrode lead.

[0013] The coating member can face the inner surface of the battery case.

[0014] The coating member can be configured to be in contact with the inner surface of the battery case.

[0015] The coating member may be more ductile than the second electrode lead.

[0016] The coating member can be configured to be electrically insulated.

[0017] The coating member may have a width greater than the width of the second electrode lead.

[0018] The first electrode lead has a width greater than the width of the second electrode lead, and the coating member may have a width smaller than the width of the first electrode lead.

[0019] The end of the second electrode lead may not be positioned beyond the end of the first electrode lead.

[0020] The coating member can cover the boundary between the first electrode lead and the second electrode lead.

[0021] The coating member can extend to the end of the first electrode lead.

[0022] The second electrode lead includes an opposing portion facing the first electrode lead and an extension portion extending away from the first electrode lead from the opposing portion, and the coating member can cover the opposing portion.

[0023] The coating member can cover all ends that are not connected to the extension of the opposing part.

[0024] The electrode tabs include a first electrode tab and a second electrode tab that extend from the same side of the electrode body and are bent in different directions, and the electrodes are provided in multiple numbers and stacked, and the multiple first electrode tabs can be welded together and joined, and the multiple second electrode tabs can be welded together and joined.

[0025] The electrode tab may include an end bend portion that is bent in the opposite direction to the direction in which the electrode tab is extended.

[0026] The end bend can cover at least a portion of the coated member.

[0027] An electrode assembly according to one embodiment of the present invention comprises an electrode including an electrode body and an electrode tab that is bent and extended from the electrode body, a first electrode lead coupled to the electrode tab, a second electrode lead coupled to the first electrode lead on the side opposite to where the first electrode lead faces the electrode tab and extending to the side opposite to where the first electrode lead faces the first electrode lead, and a coating member covering at least a portion of the edge where the first electrode lead and the second electrode lead meet.

[0028] The coating member may be more ductile than the second electrode lead.

[0029] The coating member can be configured to be electrically insulated.

[0030] The coating member may have a width greater than the width of the second electrode lead.

[0031] A lead assembly according to one embodiment of the present invention includes a first electrode lead, a second electrode lead comprising an opposing portion facing the first electrode lead and an extension portion bent from the opposing portion and extending in a direction away from the first electrode lead, and a coating member covering at least a portion of the opposing portion edge.

[0032] A lead assembly according to one embodiment of the present invention includes a coating member that covers the end of an electrode lead, thereby preventing the inner wall of a battery case from being damaged by the end of the electrode lead.

[0033] A coating member of a lead assembly according to one embodiment of the present invention is provided to be electrically insulated, thereby preventing leakage current from occurring through the coating member.

[0034] A lead assembly according to one embodiment of the present invention includes a first electrode lead coupled to a bent electrode tab, a second electrode lead coupled to the first electrode lead, and a coating member coupled to the edge of the second electrode lead facing a sealed lead sealing portion of a battery case, thereby preventing the sealing of the lead sealing portion from being released by the coating member damaging the lead sealing portion.

[0035] The electrode assembly and secondary battery of one embodiment according to the present invention can have the above effects by including the above lead assembly.

[0036] The effects obtainable from the present invention are not limited to those mentioned above, and other unmentioned effects will be clearly understood by those skilled in the art to which the present disclosure belongs from the description below.

[0037] FIG. 1 is an assembly diagram of a secondary battery according to a first embodiment of the present invention.

[0038] FIG. 2 is a perspective view and a front view of a secondary battery according to a comparative example of the present invention.

[0039] Figure 3 is a cross-sectional perspective view of the secondary battery shown in Figure 2.

[0040] Figure 4 is a perspective view and a front view of the secondary battery shown in Figure 1.

[0041] Figure 5 is a cross-sectional perspective view of the secondary battery shown in Figure 4.

[0042] Figure 6 is a cross-sectional view of the secondary battery shown in Figure 4.

[0043] Figure 7 is an assembly diagram of the electrode assembly shown in Figure 4.

[0044] FIG. 8 is a cross-sectional view of a secondary battery according to a second embodiment of the present invention.

[0045] FIG. 9 is a cross-sectional view of a secondary battery according to a third embodiment of the present invention.

[0046] FIG. 10 is a cross-sectional view of a secondary battery according to a fourth embodiment of the present invention.

[0047] Hereinafter, preferred embodiments of the present invention are described in detail with reference to the attached drawings so that those skilled in the art can easily implement the present invention. However, the present invention may be embodied in various different forms and is not limited or restricted by the following embodiments.

[0048] In order to clearly explain the present invention, detailed descriptions of related prior art that are irrelevant to the explanation or that may unnecessarily obscure the essence of the invention have been omitted. Furthermore, when assigning reference numerals to the components of each drawing in this specification, identical or similar reference numerals are assigned to identical or similar components throughout the entire specification.

[0049] Furthermore, terms and words used in this specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings, but should be interpreted in a meaning and concept consistent with the technical spirit of the invention, based on the principle that the inventor can appropriately define the concept of the terms to best describe his invention.

[0050] The various embodiments of this document and the terms used therein are not intended to limit the technical features described in this document to specific embodiments, and should be understood to include various modifications, equivalents, or substitutions of said embodiments.

[0051] In relation to the description of the drawings, similar reference numerals may be used for similar or related components.

[0052] The singular form of the noun corresponding to the item may include one or multiple items, unless the relevant context clearly indicates otherwise.

[0053] In this document, each of the phrases such as "A or B", "at least one of A and B", "at least one of A or B", "A, B or C", "at least one of A, B and C", and "at least one of A, B, or C" may include any one of the items listed together in the corresponding phrase, or all possible combinations thereof.

[0054] The term "and / or" includes a combination of multiple related described components or any of the multiple related described components.

[0055] Terms such as “first,” “second,” or “first” or “second” may be used simply to distinguish one component from another and do not limit the components in other aspects (130a-1) (e.g., importance or order).

[0056] Where any (e.g., 1st) component is referred to as "coupled" or "connected" to another (e.g., 2nd) component, with or without the terms "functionally" or "communicationly," it means that said any component may be connected to said other component directly (e.g., via a wire), wirelessly, or through a third component.

[0057] Terms such as "include" or "have" are intended to specify the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in this document, and do not preclude the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0058] When it is said that a component is "connected," "combined," "supported," or "in contact" with another component, this includes not only cases where the components are directly connected, combined, supported, or in contact, but also cases where they are indirectly connected, combined, supported, or in contact through a third component.

[0059] When it is said that a component is located "on" another component, this includes not only cases where one component is in contact with the other, but also cases where another component exists between the two components.

[0060] Meanwhile, terms such as "up-and-down direction," "downward side," and "front-backward direction" used in the following description are defined based on the drawings, and the shape and position of each component are not limited by these terms.

[0061] Hereinafter, embodiments according to the present invention will be described in detail with reference to the attached drawings.

[0062] First embodiment

[0063] FIG. 1 is an assembly diagram of a secondary battery (B) according to a first embodiment of the present invention. FIG. 6 is a cross-sectional view of the secondary battery (B) shown in FIG. 4. FIG. 7 is an assembly diagram of an electrode assembly (EA) shown in FIG. 4.

[0064] With reference to FIGS. 1, FIGS. 6 and FIGS. 7, a secondary battery (B) according to a first embodiment of the present invention will be described.

[0065] A secondary battery (B) configured to generate electricity may be provided. The secondary battery (B) may be rechargeable and rechargeable, allowing for multiple uses. The secondary battery (B) may include a battery case (10) located on the outside, an electrode assembly (EA) accommodated inside the battery case (10), and an electrolyte configured to be injected into the battery case (10). At this time, as shown in FIG. 1, the battery case (10) may be formed by a pouch film. However, if necessary, the battery case (10) may be provided in a cylindrical or prismatic shape. The electrolyte may generally refer to an electrolyte in a liquid state, but may also refer to an electrolyte in a solid state if necessary.

[0066] A battery case (10) may include a receiving portion (11) in which an electrode receiving space (11S) is formed to accommodate an electrode assembly (EA), and a side portion (12) extending from the receiving portion (11). The receiving portion (11) may be provided in a pair as shown in FIG. 1. When an electrode assembly (EA) is received in one receiving portion (11), the other receiving portion (11) covers the electrode assembly (EA) so that the electrode assembly (EA) can be received in the battery case (10). A pair of receiving portions (11) may be formed in a single battery case (10). However, if necessary, a receiving portion (11) may be formed in each of the distinct pair of battery cases (10). Furthermore, if necessary, a receiving portion (11) may be provided as a single unit.

[0067] The side portion (12) may include a lead sealing portion (12a), a degas sealing portion (12b), and / or a folding portion (12c). The lead sealing portion (12a) may be provided in a pair so as to extend in the Y direction from the receiving portion (11). The degas sealing portion (12b) may be provided in a pair so as to extend in the X direction from the receiving portion (11). The folding portion (12c) may be positioned between the pair of receiving portions (11). As illustrated in FIG. 1, the folding portion (12c) may be folded so that the pair of receiving portions (11) are positioned to face each other. When the pair of receiving portions (11) are positioned to face each other, the folded lead sealing portion (12a) may be positioned to face each other, and the pair of degas sealing portions (12b) may also be positioned to face each other. The opposing lead sealing portion (12a) and degas sealing portion (12b) can be fused together by heat and pressure to seal the receiving portion (11). Furthermore, the degas sealing portion (12b) can be trimmed to a predetermined length to reduce its length and increase the space utilization of the secondary battery (B), and the trimmed degas sealing portion (12b) can be folded again to reduce the space occupied by the degas sealing portion (12b).

[0068] The electrode assembly (EA) may include an electrode (100), a separator (not shown), and / or an electrode lead (EL). The electrode (100) and the separator may be provided in multiple numbers and arranged to be stacked alternately. In this case, the electrode (100) may include an electrode body and an electrode tab (120) extending from the electrode body. The electrode tab (120) may be formed to have a width smaller than that of the electrode body. An active material may be applied to the electrode body to directly generate electricity. The electrode tab (120) may serve as a passage for moving the electricity generated from the electrode body. The electrode tab (120) may be coupled with the electrode lead (EL) to transfer electricity back to the electrode lead (EL). The electrode lead (EL) protrudes outward from the battery case (10), so that an external component requiring electricity can come into contact with the electrode lead (EL) and receive electricity from the secondary battery (B).

[0069] At this time, since the electrode tab (120) is not a part that generates electricity, it may not contribute to the amount of electricity generated per space. Therefore, it is necessary to reduce the dead space (DS), which is the space occupied by the electrode tab (120). To solve this, a secondary battery (B) according to an embodiment of the present invention, as shown in FIG. 2, may be provided.

[0070] The electrode tab (120) may be configured to be bent downward from the electrode body rather than extending outward toward the electrode (100), so as to be in close contact with the electrode body. However, the bending direction of the electrode tab (120) may be upward rather than downward as needed, and furthermore, may be in a different direction as long as it is not parallel to the extension direction of the electrode body. The bent electrode tab (120) can form the electrode tab (120). Based on FIG. 2, one side of the electrode tab (120) is positioned facing to the right, and an electrode lead (EL) may be attached to the one side of the electrode tab (120) on the right side of the electrode tab (120). Accordingly, the distance from the electrode body to the end of the electrode tab (120) may be shorter than when the electrode tab (120) extends in a direction parallel to the electrode body. The space located on the upper and lower sides of the electrode tab (120) can form a dead space (DS) that is unnecessary for generating electricity. In particular, as shown in FIG. 7, it may be necessary to reduce the dead space distance (DD), which is the distance to the inner wall of the receiving portion (11), in order to reduce the dead space (DS).

[0071] The electrode tab (120) can be folded from the electrode body. At this time, each electrode (100) can be stacked with the electrode tab (120) already folded from the electrode body. However, if necessary, an electrode (100) including an electrode tab (120) that is not folded from the electrode body may be stacked first, and after stacking, the stacked electrode tab (120) may be folded from the electrode body.

[0072] At this time, the electrode tab (120) may include a first electrode tab (120a) extending from the electrode body and a second electrode tab (120b) extending from the same side as the side to which the first electrode tab (120a) of the electrode body extends. Based on FIG. 3, the side of the electrode body to which the first electrode tab (120a) and the second electrode tab (120b) extend may be the front. The first electrode tab (120a) and the second electrode tab (120b) may have the same polarity. For example, if the first electrode tab (120a) is positive, the second electrode tab (120b) may also be positive. Forming the electrode tab (120) having one polarity as a pair of electrode tabs (120) rather than as a single electrode tab (120) may be intended to prevent welding defects described below. Furthermore, by forming a plurality of electrode tabs (120), the resistance received by the electrode tabs (120) while electricity is transmitted through the electrode tabs (120) can be lowered. At this time, the electrode tabs (120) may be provided as a number of electrode tabs (120) greater than a pair, as needed.

[0073] The first electrode tab (120a) may be positioned to the right of the second electrode tab (120b) and bent downward, and the second electrode tab (120b) may be positioned to the left of the first electrode tab (120a) and bent upward. At this time, the electrode tab (120) can be understood as a higher concept that extracts the common features of the first electrode tab (120a) and the second electrode tab (120b). Furthermore, the bending direction of the first electrode tab (120a) only needs to be different from the bending direction of the second electrode tab (120b), and if necessary, the bending direction of the first electrode tab (120a) may be bent in a direction other than upward. Also, the position of the first electrode tab (120a) may be positioned at a location other than to the right of the second electrode tab (120b) if necessary. A first electrode tab (120a) can be stacked in multiple layers to form a first electrode tab (120a), and a second electrode tab (120b) can be stacked in multiple layers to form a second electrode tab (120b). At this time, the electrode tab (120) can be understood as a higher concept that extracts the common features of the first electrode tab (120a) and the second electrode tab (120b). At this time, the first electrode tab (120a) can be bent so that its lower surface is exposed based on the direction in which it is extended parallel to the extension direction of the electrode body before being bent. The second electrode tab (120b) can be bent so that its upper surface is exposed based on the direction in which it is extended parallel to the extension direction of the electrode body before being bent. In other words, the electrode tab (120) can be formed by sweeping a plurality of electrode tabs (120) down in one direction and bending them. Since these electrode tabs (120) protrude only slightly relative to the electrode body, the dead space (DS) can be reduced.

[0074] A first electrode lead (200) may be provided to be coupled to the first electrode tab (120a) and the second electrode tab (120b). The electrode lead (EL) described above may be a higher concept that extracts the common features of the first electrode lead (200) and the second electrode lead (300). The first electrode lead (200) may be positioned in front of the first electrode tab (120a) and the second electrode (100) tab. Accordingly, the rear surface of the first electrode lead (200) may be coupled to the lower surface of the first electrode tab (120a) before it is bent and the upper surface of the second electrode tab (120b) before it is bent. In other words, the first electrode lead (200) can be joined by overlapping with the first electrode tab (120a) and the second electrode tab (120b) and welding them in the direction in which the first electrode tab (120a) and the second electrode tab (120b) extend. At this time, the first electrode lead (200) may have a plate shape. More specifically, the first electrode lead (200) may have a plate shape and overlap with the first electrode tab (120a) and the second electrode tab (120b). The first electrode lead (200) may not be positioned beyond the stacked electrode body. However, if the first electrode lead (200) is joined with the first electrode tab (120a) and the second electrode tab (120b), it may have a shape other than a plate as needed. Furthermore, the first electrode lead (200) may be formed integrally. However, if the first electrode lead (200) is electrically connected to one another, it may be provided as an assembly of multiple components as needed. Furthermore, the first electrode lead (200) and the second electrode lead (300) may be defined as forming a lead assembly.

[0075] The degree of overlap of the electrode tab (120) may vary depending on the position. If we look at the degree of overlap of the electrode tab (120) in the first tab overlap area (A1) located on the upper side and the second tab overlap area (A2) located on the lower side of the first tab overlap area (A1) based on FIG. 4, the degree of tab overlap in the second tab overlap area (A2) is greater than the degree of tab overlap in the first tab overlap area (A1). At this time, as shown in FIG. 5, when welding is performed from the outside of the first electrode lead (200) toward the electrode tab (120) to form a welding line, if uniform thermal energy is applied to the welding line, the thermal energy from the welding can be sufficiently transferred to the electrode tab (120) in the first tab overlap area (A1), but there is a possibility that it cannot be sufficiently transferred to the electrode tab (120) closest to the electrode body in the second tab overlap area (A2). Therefore, the electrode tab (120) closest to the electrode body may not be able to be combined with the surrounding electrode tabs (120). To overcome this, the electrode tab (120) may be composed of two electrode tabs, a first electrode tab (120a) and a second electrode tab (120b), and the bending directions of the first electrode tab (120a) and the second electrode tab (120b) may be provided differently from each other. In particular, as shown in FIG. 4, when the bending direction of the second electrode tab (120b) is bent downward, there is a greater overlap of the second electrode tab (120b) in the part located relatively lower than the part located relatively higher, which poses a risk that welding will not be performed properly. Conversely, since the part located relatively lower of the bent first electrode tab (120a) has less overlap than the part located relatively higher, even if welding is not performed properly on the second electrode tab (120b), welding is performed on the first electrode tab (120a), thereby reducing the possibility of an electrode tab (120) that is not welded to the surroundings.Furthermore, additionally, if a single electrode tab (120) is provided, there is a possibility that a bending moment may occur in the direction in which the bend is released, and the first electrode lead (200) coupled to the single electrode tab (120) may rotate in one direction due to the bending moment. However, as in the first embodiment of the present invention, if a first electrode tab (120a) and a second electrode tab (120b) are provided respectively and their bending directions are different, even if a bending moment occurs in the direction in which the bend is released from the first electrode tab (120a), the bending moment generated in the direction in which the bend is released from the second electrode tab (120b) occurs in the opposite direction, so the bending moments cancel each other out, thereby preventing the first electrode lead (200) from moving. Additionally, the connection of the first electrode lead (200), the first electrode tab (120a), and the second electrode tab (120b) may be done by other methods other than welding as needed.

[0076] When the first electrode lead (200) is coupled to the first electrode tab (120a) and the second electrode tab (120b), the end of the first electrode tab (120a) may be exposed to the upper side of the first electrode lead (200), and the end of the second electrode tab (120b) may be exposed to the upper side of the first electrode lead (200). The exposed end of the first electrode tab (120a) may be bent downward so as to face the outer surface of the first electrode lead (200), and the exposed end of the second electrode tab (120b) may be bent upward so as to face the outer surface of the first electrode lead (200). In other words, the ends of the first electrode tab (120a) and the second electrode tab (120b) may be bent so as to come into contact with the opposite side facing the electrode body of the first electrode lead (200).

[0077] The second electrode lead (300) may include an opposing portion (310) facing the first electrode lead (200) and an extension portion (320) extending from the opposing portion (310) in a direction away from the electrode (100). At this time, the opposing portion (310) may extend in a direction parallel to the extension direction of the first electrode lead (200). Furthermore, the opposing portion (310) may be coupled by surface contact with the first electrode lead (200). Accordingly, the resistance between the opposing portion (310) and the first electrode lead (200) may be reduced compared to when they are coupled by point contact. The extension portion (320) may be bent from the opposing portion (310) and extended forward. However, if the extension portion (320) extends in a direction away from the electrode body, it may be extended in a direction other than forward as needed. At this time, the position of the extension portion (320) may be a position corresponding to the center of the stacking direction of the electrode body. In other words, the height (H) from the end of the receiving portion (11) to the extension portion (320) may be half the distance between a pair of receiving portions (11). Accordingly, a pair of receiving portions (11) may be formed at corresponding depths.

[0078] As described above, the electrode tab (120) is bent to reduce dead space (DS), and a first electrode lead (200) and a second electrode lead (300) may be provided to be coupled to the bent electrode tab (120).

[0079] At this time, the end of the second electrode lead (300) is formed sharply so as to cause a scratch on the inner wall of the battery case (10). This is explained with reference to the secondary battery (B) according to the comparative example of the present invention described later.

[0080] FIG. 2 is a perspective view and a front view of a secondary battery (B) according to a comparative example of the present invention. FIG. 3 is a cross-sectional perspective view of the secondary battery (B) shown in FIG. 2.

[0081] Referring to FIGS. 2 and 3, a secondary battery (B) according to a comparative example of the present invention and the problems associated therewith are described.

[0082] As described above with reference to FIG. 1, etc., the electrode lead (EL) can be positioned adjacent to the inner surface of the battery case (10). Accordingly, as shown in FIG. 3, it comes into contact with the inner wall of the battery case (10), thereby damaging the inner wall of the battery case (10) or forming a crack in the inner wall of the battery case (10).

[0083] In particular, when the battery case (10) is formed by a pouch film, since the pouch films need to be sealed by bringing them into contact with each other and applying heat to fuse them, one side of the pouch film may have a layer formed by a plastic that can be easily melted by heat. In particular, this plastic layer may include PP (Polypropylene). When the battery case (10) is formed by the pouch film, this plastic layer of the pouch film may be located on the inside of the battery case (10). The pouch film may include a metal layer on the outside of the plastic layer. When the battery case (10) is formed by the pouch film, this metal layer may be located on the outside of the plastic layer. At this time, if the plastic layer corresponding to the inner wall of the battery case (10) is damaged by the electrode lead (EL), the electrode lead (EL) and the metal layer of the battery case (10) come into contact, and electricity may flow from the electrode lead (EL) to the metal layer. In this case, a problem may occur where electricity leaks from the outer surface of the finished secondary battery (B).

[0084] Furthermore, when the battery case (10) is formed by a pouch film, the receiving portion (11) is formed by stretching the pouch film, so it is formed with a thin thickness and may be susceptible to cracking. In particular, an electrode lead (EL) located adjacent to the receiving portion (11) may easily form a crack in the receiving portion (11). Furthermore, in the case of an electrode lead (EL) adjacent to the lead sealing portion (12a), a crack may form adjacent to the lead sealing portion (12a), so there may be a risk of releasing the seal of the lead sealing portion (12a).

[0085] Considering the above points, it may be necessary to prevent damage to the inner wall of the battery case (10) caused by the electrode lead (EL).

[0086] In particular, since the second electrode lead (300) may be located closer to the inner wall of the battery case (10) than the first electrode lead (200), the second electrode lead (300) is more likely to damage the inner wall of the battery case (10) than the first electrode lead (200). Therefore, it may be necessary to prevent damage to the inner wall of the battery case (10) caused by the second electrode lead (300). In particular, the edge or end portion of the second electrode lead (300) is formed sharper than other parts, and thus the possibility of damage to the battery case (10) is high; therefore, it is necessary to prevent damage caused by the edge or end portion of the second electrode lead (300).

[0087] A secondary battery (B) according to the first embodiment of the present invention, taking this into consideration, will be described below.

[0088] FIG. 4 is a perspective view and a front view of the secondary battery (B) shown in FIG. 1. FIG. 5 is a cross-sectional perspective view of the secondary battery (B) shown in FIG. 4. FIG. 6 is a cross-sectional view of the secondary battery (B) shown in FIG. 4. FIG. 7 is an assembly drawing of the electrode assembly (EA) shown in FIG. 4.

[0089] With reference to FIGS. 4 to 7, a secondary battery (B) according to the first embodiment of the present invention will be described. At this time, in order to describe the secondary battery (B) according to the first embodiment of the present invention, some of the above descriptions may be repeated below.

[0090] As illustrated in FIG. 7, the secondary battery (B) may include a battery case (10) and an electrode assembly (EA). In this case, the electrode assembly (EA) may include an electrode (100) comprising an electrode body and an electrode tab (120) that is bent and extended from the electrode body, and / or a lead assembly coupled to the electrode tab (120). In this case, the lead assembly may include a first electrode lead (200) coupled to the electrode tab (120), and a second electrode lead (300) coupled to the first electrode lead (200) on the opposite side toward the electrode tab (120) and extending to the outside of the battery case (10). The first electrode lead (200) may have a plate shape that extends parallel to the bending direction of the electrode tab (120). More specifically, as illustrated in FIG. 4, the first electrode lead (200) may have a roughly rounded corner rectangular shape. The second electrode lead (300) may be provided by being bent to have an L shape. Specifically, the second electrode lead (300) may have a shape formed by bending a rectangular plate with rounded corners. More specifically, the second electrode lead (300) may include an opposing portion (310) facing the first electrode lead (200) and an extension portion (320) that is bent from the opposing portion (310) and extends in a direction away from the first electrode lead (200).

[0091] As shown in FIG. 4(b), the first electrode lead (200) can be prevented from being positioned beyond the thickness of the stacked electrodes (100). The end of the first electrode lead (200) may be sharp, so if it is positioned beyond the electrode (100), it may come into direct contact with the inner surface of the battery case (10) and cause impact. To prevent this, the first electrode lead (200) can be positioned so as to overlap with the stacked electrodes (100) when viewed from the direction toward the electrode tab (120), as shown in FIG. 4(b). Specifically, the first electrode lead (200) can be arranged so as to be positioned in the center when viewed from the direction toward the electrode tab (120) with respect to the stacked electrodes (100).

[0092] At this time, the end of the second electrode lead (300) may not be positioned beyond the end of the first electrode lead (200). This will be explained in more detail below.

[0093] The opposing portion (310) may be positioned to overlap with the first electrode lead (200). As illustrated in FIG. 4(b), the opposing portion (310) may be coupled to the first electrode lead (200) so as not to be exposed beyond the first electrode lead (200). If the end of the opposing portion (310) is exposed beyond the first electrode lead (200), the sharp edge of the end of the opposing portion (310) may scratch and damage the inner surface of the battery case (10). Therefore, preventing the opposing portion (310) from being exposed beyond the first electrode lead (200) may be a method to protect the inner surface of the battery case (10). Specifically, the opposing portion (310) may have a rectangular shape having a long side and a short side, and the length of the long side (W2) of the opposing portion (310) may be shorter than the length of the long side (W3) of the first electrode lead (200). Furthermore, the length of the short side of the opposing portion (310) may be shorter than the length of the cross-section of the first electrode lead (200). At this time, the center of the long side of the opposing portion (310) is positioned to correspond to the center of the long side of the first electrode lead (200), thereby preventing the ends of the long side of the opposing portion (310) from being positioned beyond the ends of the first electrode lead (200). The short side of the opposing portion (310) may be positioned close to either of the two long sides of the first electrode lead (200) so that the extension portion (320) is positioned at the center of the short side of the first electrode lead (200).

[0094] Accordingly, as illustrated in FIG. 6, the second electrode lead (300) is positioned close to the inner surface of the battery case (10), so there is a possibility that the sharp edge of the opposing portion (310) of the second electrode lead (300) may scratch the inner surface of the battery case (10). To protect against this, the lead assembly may include a coating member (500) to prevent a portion of the second electrode lead (300) from coming into contact with the inner surface of the battery case (10).

[0095] As illustrated in FIG. 7, the coating member (500) can cover at least a portion of the second electrode lead (300). More specifically, the coating member (500) can cover the end of the second electrode lead (300) that is likely to scratch the inner surface of the battery case (10). More specifically, as illustrated in FIG. 6, the coating member (500) can cover the opposing portion (310). Of course, if necessary, the end of the second electrode lead (300) facing the inner surface of the battery case (10) is not located only in the opposing portion (310), so the coating member (500) can also cover the extension portion (320) of the second electrode lead (300). Furthermore, as needed, since there is still a possibility that the end of the first electrode lead (200) may scratch the inner surface of the battery case (10), the coating member (500) may be provided to cover the end of the first electrode lead (200). However, since the part most likely to scratch the inner surface of the battery case (10) is the end of the opposing part (310) as shown in FIG. 5, the coating member (500) may be provided to cover at least a part of the end of the opposing part (310).

[0096] Additionally, there is an adhesive on the surface of the coating member (500) facing the second electrode lead (300), so that the coating member (500) and the second electrode lead (300) can be bonded by the adhesive. Furthermore, as shown in FIG. 6, the coating member (500) can also be bonded to the first electrode lead (200), so the coating member (500) can be bonded to the first electrode lead (200) in the same way as it is bonded to the second electrode lead (300).

[0097] At this time, the coating member (500) may be arranged to face the inner surface of the battery case (10), as shown in FIG. 5 or FIG. 6. Furthermore, the coating member (500) may be configured to be in contact with the inner surface of the battery case (10). Although FIG. 6 depicts the distance between the coating member (500) and the battery case (10) as being considerably far, this is merely an exaggeration to emphasize the presence of the coating member (500); it may be preferable for the distance between the coating member (500) and the inner surface of the battery case (10) to be close. This is because the space between the coating member (500) and the inner surface of the battery case (10) is a dead space (DS) that does not participate in electricity production, and reducing this space is a method to increase the electricity production per unit volume. However, if necessary, it may also be possible to form a certain distance between the coating member (500) and the inner surface of the battery case (10).

[0098] The coating member (500) may be more flexible than the second electrode lead (300). By providing the coating member (500), the coating member (500) may come into contact with the inner surface of the battery case (10) instead of the second electrode lead (300) coming into contact with the inner surface of the battery case (10). The coating member (500) may have a material that causes fewer cracks on the inner surface of the battery case (10) than the second electrode lead (300). For example, the coating member (500) may have a shock-absorbing material such as rubber. Since such a shock-absorbing material has flexibility, the coating member (500) may be more flexible than the second electrode lead (300). Alternatively, the coating member (500) may be provided with a material similar to the inner surface of the battery case (10), such as a polymer or plastic material.

[0099] The coating member (500) can be configured to be electrically insulated. The coating member (500) can prevent electricity from flowing from the second electrode lead (300) to the battery case (10). As explained in the previous description, there was a problem with electricity flowing in the battery case (10) when a crack occurred in the battery case (10). The coating member (500) prevents the second electrode lead (300) and the battery case (10) from coming into direct contact, and since the coating member (500) itself is composed of an electrical insulating material, even if the coating member (500) comes into contact with the battery case (10), it may not serve to transmit electricity from the second electrode lead (300) to the battery case (10). Considering this, the coating member (500) may, if necessary, not necessarily be positioned only at the end of the second electrode lead (300), but may be positioned to cover most or all of the second electrode lead (300) facing the inner surface of the battery case (10). Furthermore, the coating member (500) may be provided to cover the first electrode lead (200) as needed.

[0100] As shown in FIG. 4, the coating member (500) may have a roughly rectangular shape, with a long side and a short side provided. At this time, the long side of the coating member (500) may be positioned at a location corresponding to the long side of the first electrode lead (200) and the long side of the opposing part (310) of the second electrode lead (300). In particular, as shown in FIG. 5, the end corresponding to the long side of the opposing part (310) of the second electrode lead (300) may be highly likely to cause damage to the inner wall of the battery case (10). To prevent this, the coating member (500) may be provided to cover the entire end corresponding to the long side of the opposing part (310) of the second electrode lead (300). That is, the coating member (500) may have a width (W1) greater than the width (W2) of the second electrode lead (300). Here, width may be a concept corresponding to the aforementioned long side. At this time, the center of the long side of the coating member (500) may be positioned at a location corresponding to the center of the long side of the second electrode lead (300). Accordingly, as shown in FIG. 4, the coating member (500) can cover all edges that are not connected to the extension (320) of the opposing part (310). Therefore, all ends of the opposing part (310) are covered by the coating member (500) so that they do not come into direct contact with the inner wall of the battery case (10).

[0101] Furthermore, the coating member (500) may have a width (W1) smaller than the width of the first electrode lead (200). If the coating member (500) is longer than the width (W3) of the first electrode lead (200), the coating member (500) may be exposed beyond the first electrode lead (200). Since the portion of the coating member (500) exposed beyond the first electrode lead (200) only occupies volume unless it serves a special function, it may increase dead space (DS). Therefore, the coating member (500) may overlap with the first electrode lead (200) and may not be positioned beyond the first electrode lead (200).

[0102] As illustrated in FIG. 5, the coating member (500) can cover the boundary between the first electrode lead (200) and the second electrode lead (300). The first electrode lead (200) and the second electrode lead (300) can be joined by a method such as welding. At this time, the joining of the first electrode lead (200) and the second electrode lead (300) may not be perfect, and the joining may be released. In particular, an electrolyte (not shown) may be contained within the secondary battery (B), and the electrolyte may react with the surrounding components while the secondary battery (B) produces electricity. Accordingly, if the coating member (500) does not cover the boundary between the first electrode lead (200) and the second electrode lead (300), the electrolyte may penetrate between the first electrode lead (200) and the second electrode lead (300), thereby weakening the bonding force between the first electrode lead (200) and the second electrode lead (300). Considering this, the first embodiment of the present invention, as shown in FIG. 6, only covers the space between the upper side of the second electrode lead (300) opposing portion (310) and the first electrode lead (200), but if necessary, it may also be possible to provide a separate coating member (500) to cover the space between the lower side of the extension portion (320) and the first electrode lead (200). Furthermore, since the coating member (500) covers the space between the first electrode lead (200) and the second electrode lead (300), the first electrode lead (200) and the second electrode lead (300) are joined by the coating member (500). Therefore, even if the connection between the first electrode lead (200) and the second electrode lead (300) is accidentally detached due to the coating member (500) being positioned between the first electrode lead (200) and the second electrode lead (300), the connection between the first electrode lead (200) and the second electrode lead (300) may be maintained by the coating member (500).

[0103] As illustrated in FIG. 6, the coating member (500) may extend to the end of the first electrode lead (200). As explained above, it is not desirable for the coating member (500) to be exposed to the outside of the first electrode lead (200). However, as the surface area of ​​the coating member (500) in contact with the first electrode lead (200) increases, the bonding force of the coating member (500) with the first electrode lead (200) becomes stronger, thereby making the bonding force between the first electrode lead (200) and the second electrode lead (300) stronger as described above. Furthermore, as the surface area of ​​the coating member (500) in contact with the first electrode lead (200) increases, the coating member (500) can reduce the surface area where the first electrode lead (200) directly contacts the inner surface of the battery case (10), thereby mitigating the cracking problem that occurs when the battery case (10) comes into contact with the first electrode lead (200), which has high rigidity. Furthermore, as the surface area of ​​the coating member (500) in contact with the first electrode lead (200) increases, incidental problems arising from the first electrode lead (200) coming into contact with the electrolyte may be reduced. Considering this, the coating member (500) needs to come into contact with the first electrode lead (200) extensively without being positioned beyond the first electrode lead (200). Accordingly, the coating member (500) can be extended to the end of the first electrode lead (200).

[0104] Additionally, as illustrated in FIG. 4, when the electrode tab (120) is bent and extended once, it can extend beyond the electrode body to form an end bend. Since the end bend extending beyond the electrode body can form unnecessary dead space (DS), it can be modified to occupy less space. That is, the end bend can be bent in the opposite direction to the direction in which the electrode tab (120) is bent and extended. Accordingly, the end bend can cover at least a portion of the coating member (500).

[0105] The first embodiment and other embodiments are described below. Content common to the first embodiment will be omitted as much as possible, and the other embodiments will be described focusing on the differences. In other words, it is obvious that if content not explained in the other embodiments is necessary, it can be supplemented through the content of the first embodiment.

[0106] 2nd embodiment

[0107] FIG. 8 is a cross-sectional view of a secondary battery (B-1) according to a second embodiment of the present invention.

[0108] Referring to FIG. 8, an electrode assembly (EA-1) including a coating member (500-1) according to a second embodiment of the present invention is described.

[0109] The second embodiment differs from the first embodiment in that the coating member (500-1) covers only the end edge of the second electrode lead (300) and does not cover the first electrode lead (200).

[0110] Since the coating member (500-1) according to the second embodiment has a smaller area covered by the coating member (500) than the first embodiment, the use of the coating member (500-1) can be minimized.

[0111] Third embodiment

[0112] FIG. 9 is a cross-sectional view of a secondary battery (B-2) according to a third embodiment of the present invention.

[0113] Referring to FIG. 9, an electrode assembly (EA-2) including a coating member (500-2) according to a third embodiment of the present invention is described.

[0114] The third embodiment differs from the first embodiment in that the coating member (500-2) also covers the end of the first electrode lead (200).

[0115] The coating member (500-2) can be bent at the end of the first electrode lead (200) and bent toward the electrode tab (120). Accordingly, the end of the first electrode lead (200) can be prevented from damaging the inner wall of the battery case (10).

[0116] 4th embodiment

[0117] FIG. 10 is a cross-sectional view of a secondary battery (B-3) according to the fourth embodiment of the present invention.

[0118] Referring to FIG. 10, an electrode assembly (EA-3) including a coating member (500) according to a fourth embodiment of the present invention is described.

[0119] The fourth embodiment differs from the first embodiment in that a second coating member (500'-3) covering the end of the electrode tab (120) is provided.

[0120] A first coating member (500-3) that performs a corresponding role to the coating member (500) having the features of the first embodiment, and a second coating member (500'-3) that covers the electrode tab (120) may be provided. The second coating member (500'-3) may cover the end bend portion of the electrode tab (120). Since the end of the end bend portion is also formed sharply and is similar to the second electrode lead (300) in that it can cause damage to the inner wall of the battery case (10), the second coating member (500'-3) may be provided to perform a similar role to the first coating member (500-3). However, the second coating member (500'-3) may cover both the end bend portion and the first electrode lead (200).

[0121] The secondary battery, electrode assembly, and lead assembly described above may be said to have the following characteristics in order to have the effects of the present invention. The description of the embodiments above can be understood as an embodiment of the concept of the present invention below.

[0122] A secondary battery may include a battery case, an electrode accommodated in the battery case, the electrode comprising an electrode body and an electrode tab bent and extended from the electrode body, a first electrode lead coupled to the electrode tab, a second electrode lead coupled to the first electrode lead on the opposite side toward the electrode tab toward the first electrode lead and extending to the outside of the battery case, and a coating member covering at least a portion of the end of the second electrode lead.

[0123] The electrode assembly may include an electrode comprising an electrode body and an electrode tab that is bent and extends from the electrode body, a first electrode lead coupled to the electrode tab, a second electrode lead coupled to the first electrode lead on the side opposite to where the first electrode lead faces the electrode tab and extending to the side opposite to where the first electrode lead faces the first electrode lead, and a coating member covering at least a portion of the edge where the first electrode lead and the second electrode lead meet.

[0124] The lead assembly may include a first electrode lead, a second electrode lead comprising an opposing portion facing the first electrode lead and an extension portion bent from the opposing portion and extending in a direction away from the first electrode lead, and a coating member covering at least a portion of the opposing portion edge.

[0125] Unless explicitly stated otherwise, the embodiments described above may be combined with other embodiments. Alternatively, unless explicitly limited in the combination of any embodiment with another, it should be considered that combinations between embodiments are possible. Any combination of any embodiment with another embodiment is deemed to be disclosed herein.

[0126] Although the present invention has been described above by limited embodiments and drawings, the present invention is not limited thereto, and various implementations are possible within the scope of the technical spirit of the present invention and the equivalent scope of the claims described below by those skilled in the art to which the present invention belongs.

[0127] [Explanation of the symbol]

[0128] B: Secondary battery

[0129] 10: Battery case

[0130] 11: Reception Department

[0131] 11S: Electrode receiving space

[0132] 12: Side

[0133] 12a: Lead sealing part

[0134] 12b: Degas sealing part

[0135] 12c: Folding part

[0136] EA: Electrode assembly

[0137] 100: Electrode

[0138] 110: Electrode body

[0139] 120: Electrode tab

[0140] 120a: First electrode tab

[0141] 120b: Second electrode tab

[0142] EL: Electrode lead

[0143] 200: First electrode lead

[0144] 300: Second electrode lead

[0145] 310: Opposite part

[0146] 320: Extension part

[0147] 400: Lead film

[0148] 500: Coating member

[0149] 500-3: First coating member

[0150] 500'-3: Second coating member

[0151] DS: Dead Space

[0152] DD: Dead Space Distance

[0153] H: Lead height

[0154] A1: 1st tab nested area

[0155] A2: 2nd tab nested area

Claims

1. Battery case; An electrode accommodated in the above-mentioned battery case, comprising an electrode body and an electrode tab that is bent and extended from the electrode body; A first electrode lead coupled to the electrode tab above; A second electrode lead that is coupled to the first electrode lead on the opposite side toward the first electrode lead toward the electrode tab and extends to the outside of the battery case; and A secondary battery comprising a coating member covering at least a portion of the second electrode lead end.

2. In Paragraph 1, The above coating member is a secondary battery facing the inner surface of the battery case.

3. In Paragraph 1, The above coating member is configured to be in contact with the inner surface of the battery case, for a secondary battery.

4. In Paragraph 1, The above coating member is a secondary battery that is more flexible than the second electrode lead.

5. In Paragraph 1, The above-mentioned coating member is configured to be electrically insulated, in a secondary battery.

6. In Paragraph 1, The above coating member is a secondary battery having a width greater than the width of the second electrode lead.

7. In Paragraph 1, The first electrode lead has a width greater than the width of the second electrode lead, The above coating member is a secondary battery having a width smaller than the width of the first electrode lead.

8. In Paragraph 1, A secondary battery in which the end of the second electrode lead is not positioned beyond the end of the first electrode lead.

9. In Paragraph 1, The above coating member is a secondary battery that covers the boundary between the first electrode lead and the second electrode lead.

10. In Paragraph 1, The above coating member is a secondary battery extending to the end of the first electrode lead.

11. In Paragraph 1, The second electrode lead above is, A counter portion facing the first electrode lead; and It includes an extension portion extending in a direction away from the first electrode lead at the above-mentioned opposite portion, The above coating member is a secondary battery covering the above-mentioned opposing portion.

12. In Paragraph 11, The above coating member is a secondary battery that covers all ends not connected to the extension of the opposite part.

13. In Paragraph 1, The electrode tab includes a first electrode tab and a second electrode tab that extend from the same side of the electrode body and are bent in different directions. The above electrodes are provided in multiple numbers and stacked, and A plurality of the above-mentioned first electrode tabs are welded together and joined, A secondary battery in which a plurality of the above-mentioned second electrode tabs are welded together.

14. In Paragraph 1, The above electrode tab is a secondary battery comprising an end bend portion that is bent in the opposite direction to the direction in which the electrode tab is extended.

15. In Paragraph 14, The above-mentioned end bending portion covers at least a portion of the coating member, a secondary battery.

16. An electrode comprising an electrode body and an electrode tab that is bent and extended from the electrode body; A first electrode lead coupled to the electrode tab above; A second electrode lead coupled to the first electrode lead on the opposite side toward the first electrode lead toward the electrode tab and extending toward the opposite side toward the first electrode lead; and An electrode assembly comprising a coating member that covers at least a portion of the edge where the first electrode lead and the second electrode lead come into contact.

17. In Paragraph 16, The above coating member is an electrode assembly that is more flexible than the second electrode lead.

18. In Paragraph 16, The above coating member is an electrode assembly configured to be electrically insulated.

19. In Paragraph 16, The above coating member is an electrode assembly having a width greater than the width of the second electrode lead.

20. First electrode lead; A second electrode lead comprising an opposing portion facing the first electrode lead and an extension portion bent at the opposing portion and extending in a direction away from the first electrode lead; and A lead assembly comprising a coating member covering at least a portion of the opposing edge.

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