Battery cells, and battery packs including said battery cells and automobiles

Abstract

A battery cell according to one embodiment of the present invention includes: an electrode assembly comprising a first electrode having a first blank portion, a second electrode having a second blank portion, and a separator interposed between them; a battery housing configured to house the electrode assembly through an opening provided on one side; and a first current collector provided on the opening side and configured to electrically connect the first blank portion and the battery housing, wherein the first current collector may be configured such that at least a portion of it separates from the battery housing when the internal pressure rises above a reference value.

Description

Technical Field

[0001] The present invention relates to a battery cell, a battery pack including the battery cell, and a vehicle.

[0002] This application claims priority based on Korean Patent Application No. 10-2023-0135959 filed on October 12, 2023, and all the contents disclosed in the specification and drawings of the application are incorporated into this application.

Background Art

[0003] Secondary battery cells, which are highly applicable to a variety of products and have electrical characteristics such as high energy density, are widely used not only in portable devices but also in electric vehicles (EVs) or hybrid electric vehicles (HEVs) driven by an electric power source. Such secondary battery cells not only have the primary advantage of significantly reducing the use of fossil fuels but also have the advantage of generating no by-products associated with energy use, and thus are attracting attention as a new energy source for improving environmental friendliness and energy efficiency.

[0004] According to the charge / discharge capacity of a battery pack required by an electric vehicle (EV) or a hybrid electric vehicle (HEV), a plurality of battery cells may be connected in series / parallel to form a battery pack. In this case, it is common to first form a battery module including at least one battery cell and then add other components to the at least one battery module to form a battery pack or a battery rack. In recent years, a cell-to-pack type battery pack that directly houses a plurality of battery cells in a pack housing or the like without modularizing them has also been manufactured.

[0005] However, in the case of battery packs containing multiple lithium secondary battery cells, the damage caused by fire and explosion is even more severe. Fires in battery packs begin due to abnormal temperature increases and internal gas generation in the battery cells located inside, caused by overcharging or other factors. Consequently, when the internal pressure of the battery cells rises above a certain level, venting occurs, and high-temperature sparks containing high-temperature gas, electrode active material, and aluminum particles are ejected outwards from the battery cells.

[0006] On the other hand, conventional cylindrical battery cells have a beading portion that is press-fitted inward at the end adjacent to the opening of the battery housing in order to prevent vertical movement of the electrode assembly inside the battery housing.

[0007] When a thermal event such as thermal runaway occurs inside a cylindrical battery cell, high temperature and pressure are applied to the sides of the battery housing, such as the beading area. This prevents the flame from being released towards the opening, resulting in a side rupture phenomenon where the flame is ejected while destroying the sides of the battery housing, such as the beading area. When a side rupture occurs, the ejected flame can directly target other adjacent cylindrical battery cells, potentially causing a chain reaction of thermal runaway.

[0008] Therefore, there is a need to develop battery cells that can minimize the high temperature and high pressure applied to the sides of the battery housing, such as the beading area, when thermal events occur, thereby suppressing the occurrence of side rupture.

[0009] In particular, there is a need to develop battery cells that can guide the flame towards the opening of the battery housing when a thermal event occurs, thereby suppressing the occurrence of side rupture. [Overview of the project] [Problems that the invention aims to solve]

[0010] Therefore, the present invention has been made to solve the above-mentioned problems, and aims to provide a battery cell that can ensure safety and reliability when a battery cell experiences thermal runaway, as well as a battery pack and an automobile containing the same.

[0011] Furthermore, the problems that this invention aims to solve are not limited to those described above, and other problems not mentioned can be clearly understood by those skilled in the art from the description of the invention below. [Means for solving the problem]

[0012] A battery cell according to one embodiment of the present invention for solving the above-mentioned problems includes: an electrode assembly including a first electrode having a first blank portion, a second electrode having a second blank portion, and a separator interposed between them; a battery housing configured to house the electrode assembly through an opening provided on one side; and a first current collector provided on the opening side and configured to electrically connect the first blank portion and the battery housing, wherein the first current collector may be configured such that at least a portion of it separates from the battery housing when the internal pressure rises above a reference value.

[0013] A welded joint is formed between the first current collector and the inner surface of the battery housing, so that at least a portion of the first current collector can be welded to the inner surface of the battery housing.

[0014] The first current collector includes a first blank portion connecting portion disposed on the upper part of the electrode assembly and coupled to the first blank portion, and a plurality of housing connecting portions disposed on the inner surface of the battery housing, wherein at least one welded portion may be provided between at least one of the plurality of housing connecting portions and the inner surface of the battery housing.

[0015] The first current collector further includes a support portion positioned on top of the electrode assembly, and the first plain portion coupling and a plurality of housing couplings may be formed extending from the support portion.

[0016] Each of the aforementioned housing joints may include a contact portion welded to the inner surface of the battery housing and a connecting portion that connects the support portion and the contact portion.

[0017] The contact portions may be provided spaced apart from each other along the circumferential direction of the electrode assembly.

[0018] The aforementioned welded portion may be provided for each of the plurality of housing joint portions.

[0019] The welded portion may include a weak area with low weld strength.

[0020] The welding strength of the aforementioned weak point is 10 kgf / cm². 2 The following are possible:

[0021] Multiple welds can be formed within the same housing joint between the inner surface of the battery housing and the plurality of housing joints.

[0022] The number of welds formed within one housing joint may be configured to differ for each of the multiple housing joints.

[0023] The battery housing includes a beading portion formed at the end adjacent to the opening and press-fitted inward, and the welded portion may be provided between the beading portion and the plurality of housing joints.

[0024] The beading portion has a flat section parallel to the bottom surface of the battery housing in at least a portion of the area, and the radial width of the welded portion may be configured to be 20% or less of the length of the flat section.

[0025] The welding part may be provided only in a part of the plurality of housing coupling parts.

[0026] The battery cell according to an embodiment of the present invention may further include a housing cover configured to seal the opening and having a vent part.

[0027] The battery cell according to an embodiment of the present invention may further include a terminal that penetrates the battery housing and is electrically connected to the second plain part on the opposite side of the opening.

[0028] The battery cell according to an embodiment of the present invention may further include a second current collector located between the electrode assembly and the terminal, and the second current collector may include a second plain part coupling part coupled to the second plain part and a terminal coupling part coupled to the terminal.

[0029] On the other hand, a battery pack according to an embodiment of the present invention includes a plurality of battery cells according to an embodiment of the present invention described above.

[0030] An automobile according to an embodiment of the present invention includes a battery pack according to an embodiment of the present invention described above.

Advantages of the Invention

[0031] According to one aspect of the present invention, when a thermal event occurs in a battery cell, the high temperature and high pressure applied to the side surface of the housing are minimized to suppress the occurrence of a side rupture phenomenon, and the safety and reliability of the battery cell can be ensured.

[0032] Also, according to one aspect of the present invention, when a thermal event occurs in a battery cell, the first current collector is quickly separated from the housing, so that the electrode assembly is discharged outside the housing, and the heat and pressure inside the housing can be minimized.

[0033] Furthermore, according to one aspect of the present invention, gases, flames, etc., generated in the event of a battery cell malfunction are rapidly and directionally discharged to the outside of the housing, thereby minimizing thermal damage to other battery cells.

[0034] This makes it possible to prevent or delay events associated with thermal runaway in battery packs and devices that contain them, such as fires and explosions.

[0035] In particular, in electric vehicles, suppressing or delaying the propagation of thermal runaway between battery cells can ensure sufficient time for occupants to escape or for the vehicle to continue moving.

[0036] The present invention also has various other effects, which will be explained in each embodiment, or effects that can be easily inferred by those skilled in the art will be omitted from the explanation.

[0037] The drawings accompanying this specification illustrate preferred embodiments of the present invention and, together with the detailed description of the invention described later, serve to further illustrate the technical idea of ​​the present invention. Therefore, the present invention is not to be construed as being limited only to what is shown in the drawings. [Brief explanation of the drawing]

[0038] [Figure 1] This is an overall perspective view of a battery cell according to one embodiment of the present invention. [Figure 2] This is a perspective view of an electrode assembly included in a battery cell according to one embodiment of the present invention. [Figure 3] This is a cross-sectional view of a battery cell relating to Entity Model 1. [Figure 4] This is a schematic cross-sectional view showing the state in which the first current collector included in a battery cell according to one embodiment of the present invention is separated from the battery housing when a thermal event occurs. [Figure 5] This is a perspective view of a first current collector included in a battery cell according to one embodiment of the present invention. [Figure 6] This is a plan view showing the internal structure of a battery cell according to one embodiment of the present invention. [Figure 7] This is an enlarged view of portion A in Figure 3, and is a diagram illustrating the welded portion included in a battery cell according to one embodiment of the present invention. [Figure 8] This is a cross-sectional view showing the state in which a first current collector included in a battery cell according to one embodiment of the present invention is separated from the battery housing when a thermal event occurs. [Figure 9] This is a plan view of a battery cell according to another embodiment of the present invention. [Figure 10] This is a cross-sectional view showing a state in which a part of the first current collector included in a battery cell according to one embodiment of the present invention is coupled to the battery housing. [Figure 11] This is a cross-sectional view showing a state in which a portion of the first current collector included in a battery cell according to one embodiment of the present invention separates from the battery housing when a thermal event occurs. [Figure 12] This figure shows a second current collector included in a cylindrical battery cell according to one embodiment of the present invention. [Figure 13] This figure shows a schematic configuration of a battery pack including a cylindrical battery cell according to one embodiment of the present invention. [Figure 14] This figure shows a schematic configuration of an automobile including a battery pack according to one embodiment of the present invention. [Modes for carrying out the invention]

[0039] Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Prior to this, terms and phrases used in this specification and in the claims should not be interpreted in a manner limited to their ordinary or dictionary meanings, but rather in a manner consistent with the technical idea of ​​the present invention, based on the principle that inventors may appropriately define the concepts of terms in order to best describe their invention.

[0040] Therefore, the embodiments described herein and the configurations shown in the drawings represent only one of the most preferred embodiments of the present invention and do not represent the entirety of the technical idea of ​​the present invention. It should be understood that a variety of equivalents and modifications may exist that can be substituted for these at the time of filing.

[0041] Furthermore, the present invention includes a variety of embodiments. In each embodiment, redundant explanations of substantially identical or similar configurations will be omitted, and the focus will be on the differences.

[0042] On the other hand, while the present invention may use terms indicating directions such as up, down, left, right, front, and back, these terms are for convenience of explanation and it is obvious to those skilled in the art that they can change depending on the position of the object, the observer's position, etc.

[0043] For the sake of explanation, in this specification, the direction along the longitudinal direction of the winding axis of an electrode assembly wound in a jelly roll shape is referred to as the axial direction. The direction surrounding the winding axis is referred to as the circumferential direction. The direction approaching the winding axis or moving away from the winding axis is referred to as the radial direction. Of these, the direction approaching the winding axis is specifically referred to as the centripetal direction, and the direction moving away from the winding axis is referred to as the centrifugal direction.

[0044] Figure 1 is an overall perspective view of a battery cell 1 according to one embodiment of the present invention, Figure 2 is a perspective view of an electrode assembly 10 included in the battery cell 1 according to one embodiment of the present invention, and Figure 3 is a cross-sectional view of the battery cell 1 according to one embodiment of the present invention. Figure 4 is a schematic cross-sectional view showing the state in which the first current collector 30 included in the battery cell 1 according to one embodiment of the present invention is separated from the battery housing 20 when a thermal event occurs.

[0045] First, referring to Figure 1, a battery cell 1 according to one embodiment of the present invention includes an electrode assembly 10, a battery housing 20, and a first current collector 30. The battery cell 1 of the present invention is not limited by the shape of the battery cell, and may be, for example, a cylindrical battery cell.

[0046] When the battery cell 1 according to one embodiment of the present invention is configured as a cylindrical battery cell, referring to Figure 2, the electrode assembly 10 may include winding holes H1 formed in the core portion of the electrode assembly 10. The electrode assembly 10 may also include a first blank portion 11 and a second blank portion 12.

[0047] More specifically, the electrode assembly 10 may have a structure in which a first electrode, a second electrode, and the separator interposed between them are wound around a winding axis with a separator in between, thereby defining the core and the outer surface. That is, the electrode assembly 10 applied to the present invention may be a jelly roll type electrode assembly 10. In this case, an additional separator may be provided on the outer surface of the electrode assembly 10 for insulation from the battery housing 20. The electrode assembly 10 may have a winding structure well known in the industry.

[0048] The first electrode may include a first electrode current collector and a first electrode active material coated on one or both sides of the first electrode current collector. One end of the first electrode in the width direction (parallel to the height direction of the battery cell 1 shown in Figure 1) may have a plain area where the first electrode active material is not coated. That is, the first electrode may include a plain area on the long side end along the winding direction where the active material is not coated and is exposed to the outside of the separator. The plain area that functions as the first electrode tab will be hereinafter referred to as the first plain area 11.

[0049] The first blank portion 11 may be provided at the top of the electrode assembly 10 housed in the battery housing 20 in the height direction (parallel to the height direction of the battery cell 1 shown in Figure 1). That is, the first electrode includes the first blank portion 11, which has no active material layer applied to its long edge and is exposed to the outside of the separator, and at least a portion of the first blank portion 11 can be used as an electrode tab itself. The first blank portion 11 may be, for example, a negative electrode tab.

[0050] The second electrode may include a second electrode current collector and second electrode active material coated on one or both sides of the second electrode current collector. The other end of the second electrode in the width direction (parallel to the height direction of the battery cell 1 shown in Figure 1) may have a plain area where the second electrode active material is not coated. That is, the second electrode may include a plain area at the long end along the winding direction where the active material is not coated and is exposed to the outside of the separator. The plain area that functions as a second electrode tab will hereinafter be referred to as the second plain area 12.

[0051] The second blank portion 12 may be provided at the lower part of the electrode assembly 10 in the height direction, which is housed within the battery housing 20. That is, the second electrode includes the second blank portion 12, which does not have an active material layer applied to its long edge and has a separator exposed to the outside, and at least a portion of the second blank portion 12 may be used as an electrode tab itself. The second blank portion 12 may be, for example, a positive electrode tab.

[0052] On the other hand, in the present invention, the positive electrode active material applied to the positive electrode current collector and the negative electrode active material applied to the negative electrode current collector can be any active material known in the industry without limitation.

[0053] At least a portion of the first plain section 11 may include a plurality of segmented pieces 11a divided along the winding direction of the electrode assembly 10. In this case, the plurality of segmented pieces 11a may be bent along the radial direction of the electrode assembly 10.

[0054] Referring to Figure 2, the plain sections 11 and 12 can be bent along the radial direction of the electrode assembly 10, for example, from the outer circumference to the core. In this case, the multiple divided pieces 11a of the bent first plain section 11 can overlap in multiple layers to form a bent surface. In this case, the current collector 30, which will be described later, can be welded to a predetermined area while seated on the bent surface of the first plain section 11. Such a structure for the first electrode can be similarly applied to the second electrode.

[0055] On the other hand, referring to Figures 1 to 4, the battery housing 20 may have an opening formed on one side in the height direction (parallel to the Z-axis). The battery housing 20 can accommodate the electrode assembly 10 through the opening. That is, the battery housing 20 may have a configuration in which the upper end in the height direction is open and the lower end is closed. The battery housing 20 is configured as a substantially cylindrical housing and may contain a conductive metal.

[0056] Referring to Figures 1 and 2, a first current collector 30 included in a battery cell 1 according to one embodiment of the present invention may be configured to be electrically connected to an electrode assembly 10 and a battery housing 20. That is, the first current collector 30 can electrically connect the electrode assembly 10, for example, the first blank portion 11, to the battery housing 20. The first current collector 30 may be housed inside the battery housing 20 and provided on the opening side. In this case, the first current collector 30 may be coupled to the inner surface of the battery housing 20.

[0057] As shown in the embodiment in Figure 4, the first current collector 30 may be configured such that at least a portion of it separates from the battery housing 20 when the internal pressure rises above a reference value due to a thermal event. In some cases, only a portion of the first current collector 30 separates from the battery housing 20, while in other cases, the entire first current collector 30 separates from the battery housing 20. According to the above embodiment of the present invention, before a thermal event occurs and the high pressure inside the battery housing 20 causes the side of the battery housing 20 to rupture, at least a portion of the first current collector 30 can be separated from the battery housing 20 by pressure such as gas, and the opening can be opened. That is, when a thermal event occurs, at least a portion of the first current collector 30 separates from the battery housing 20, and a space can be secured from which gas, flame and / or electrode assembly 10 can be discharged.

[0058] When at least a portion of the first current collector 30 is separated from the battery housing 20, the first current collector 30 may take on a shape that is inverted vertically from its normal state, as shown in the embodiment in Figure 4. That is, in the normal state, the portion of the first current collector 30 that is connected to the battery housing 20 (the housing connection portion 32, described later) may be located above the portion of the first current collector 30 that is connected to the first blank portion 11 (the first blank portion connection portion 31, described later). In contrast, when a thermal event occurs, the portion of the first current collector 30 that is connected to the first blank portion 11 (the first blank portion connection portion 31) may be bent upward so that it is located above the portion of the first current collector 30 that is connected to the battery housing 20 (the housing connection portion 32, described later).

[0059] To allow at least a portion of the first current collector 30 to be easily separated from the battery housing 20, for example, the first current collector 30 may be welded to the battery housing 20 with a weak weld strength. Alternatively, only a portion of the first current collector 30 may be welded to the battery housing 20.

[0060] If a thermal event such as thermal runaway occurs inside the battery housing 20, a side rupture phenomenon may occur in which the side of the battery housing 20 is destroyed by high temperature and pressure from gas or flames. According to the above embodiment of the present invention, when a thermal event occurs in the battery cell 1, the first current collector 30 can be quickly separated from the battery housing 20, and the electrode assembly 10 can be quickly discharged to the outside of the battery housing. This minimizes the high temperature and pressure applied to the inner surface of the battery housing 20, thereby suppressing the occurrence of a side rupture phenomenon and ensuring the safety and reliability of the battery cell 1.

[0061] Furthermore, according to the above embodiment of the present invention, gases, flames, etc., are quickly and directionally discharged to the outside of the battery housing 20 towards the opening rather than the side of the battery housing 20, thereby minimizing thermal damage to other battery cells.

[0062] More specifically, at least a portion of the first current collector 30 can be bonded to the inner surface of the battery housing 20. For example, at least a portion of the first current collector 30 and the inner surface of the battery housing 20 can be joined by welding. This allows a welded joint W to be formed between at least a portion of the first current collector 30 and the inner surface of the battery housing 20, as shown in Figure 3. For welding to join the battery housing 20 and the first current collector 30, for example, laser welding, ultrasonic welding, or spot welding may be applied. After housing the electrode assembly 10 inside the battery housing 20 through the opening, at least a portion of the first current collector 30 can be pre-welded to the battery housing 20.

[0063] Figure 5 is a perspective view of the first current collector included in a battery cell according to one embodiment of the present invention.

[0064] A first current collector 30 according to one embodiment of the present invention will be described in detail with reference to Figures 3 and 5. The first current collector 30 may include a first plain portion coupling portion 31 and a housing coupling portion 32.

[0065] The first plain section connecting portion 31 is positioned on the upper part of the electrode assembly 10 and may be connected to the first plain section 11. At least one of the first plain section connecting portions 31 may be provided. The first plain section connecting portion 31 may be connected to the first plain section 11 by welding, for example, along the radial direction of the electrode assembly 10.

[0066] The housing coupling portion 32 may be positioned on the inner surface of the battery housing 20. At least one housing coupling portion 32 may be provided. For example, as shown in Figure 5, the first current collector 30 may include a plurality of housing coupling portions 32.

[0067] At least one first plain section coupling 31 and a plurality of housing couplings 32 may be arranged, for example, in a substantially radial, cross-shaped, or a combination thereof, relative to the center of the first current collector 30. From another viewpoint, each of the plurality of housing couplings 32 may be arranged between adjacent first plain section couplings 31.

[0068] In this case, at least one of the multiple housing joints 32 can be welded to the inner surface of the battery housing 20. That is, at least one welded joint W can be provided between at least one of the multiple housing joints 32 and the inner surface of the battery housing 20.

[0069] On the other hand, the first current collector 30 may further include a support portion 33. The support portion 33 may be located on top of the electrode assembly 10. The first plain portion coupling portion 31 and the plurality of housing coupling portions 32 may be formed by extending from the support portion 33.

[0070] The first blank portion connecting portion 31 and the housing connecting portion 32 may be indirectly connected via the support portion 33 and not directly connected to each other. According to the above embodiment of the present invention, when an external impact is applied to the cylindrical battery 1 of the present invention, the possibility of damage occurring at the connection portion between the first current collector 30 and the electrode assembly 10, and at the connection portion between the first current collector 30 and the battery housing 20 can be minimized.

[0071] The first plain section connecting portion 31 may have a shape that extends substantially radially from the support portion 33 toward the side wall of the battery housing 20. Each of the first plain section connecting portions 31 may be arranged spaced apart from one another along the periphery of the support portion 33.

[0072] The multiple housing coupling portions 32 may have a shape that extends substantially radially from the support portion 33 toward the side wall of the battery housing 20. Each of the multiple housing coupling portions 32 may be arranged spaced apart from one another along the periphery of the support portion 33.

[0073] In order to increase the bonding area between the first current collector 30 and the electrode assembly 10 to ensure bonding strength and reduce electrical resistance, not only the first blank bonding portion 31 but also the support portion 33 can be bonded to the first blank portion 11. The support portion 33 and the first blank portion 11 can be bonded by welding.

[0074] Each of the multiple housing coupling portions 32 may include a contact portion 32a and a connecting portion 32b. The contact portion 32a may be welded onto the inner surface of the battery housing 20. Multiple contact portions 32a may be provided, and at least one of these contact portions 32a may be welded onto the inner surface of the battery housing 20. The multiple contact portions 32a may be spaced apart from each other along the circumferential direction of the electrode assembly 10.

[0075] The connecting portion 32b may be configured to connect the support portion 33 and the contact portion 32a. The connecting portion 32b may be positioned so that at least a portion of it is in contact with the first plain portion 11.

[0076] On the other hand, referring to Figure 5, the support portion 33 may be provided with a current collector hole H2 formed at a position corresponding to the winding hole H1 formed in approximately the center of the electrode assembly 10. The winding hole H1 and the current collector hole H2, which communicate with each other, can function as a passage for inserting a welding rod for welding the terminal 50 to the second current collector 60, or for welding the terminal 50 to a lead tab (not shown), or for laser beam irradiation.

[0077] Furthermore, the first current collector 30 of the present invention may be provided with at least one electrolyte injection hole H3. The electrolyte injection hole H3 may be provided in the first blank portion coupling portion 31. This allows the electrolyte to be injected after the coupling including the electrode assembly 10 and the first current collector 30 is housed in the battery housing 20 when manufacturing the battery cell 1 according to one embodiment of the present invention. At this time, the electrolyte injection may be improved by the electrolyte injection hole H3.

[0078] Figure 6 is a plan view of a battery cell according to one embodiment of the present invention, and Figure 7 is an enlarged view of part A in Figure 3, illustrating the welded portion included in the battery cell according to one embodiment of the present invention. Figure 8 is a cross-sectional view showing the state in which the first current collector included in the battery cell according to one embodiment of the present invention is separated from the battery housing when a thermal event occurs.

[0079] According to one embodiment of the present invention, as shown in the embodiment in Figure 6, a welded portion W may be provided for each of the multiple housing joints 32. That is, all of the contact portions 32a of the multiple housing joints 32 may be welded to the inner surface of the battery housing 20.

[0080] According to the above embodiment of the present invention, the connection between the first current collector 30 and the battery housing 20 can be stably maintained under normal conditions. Furthermore, in the event of a thermal event, at least a portion of the first current collector 30 can be easily separated from the battery housing 20, thereby ensuring the thermal stability of the battery cell 1.

[0081] In this case, the welded joint W may include a weak area V with low weld strength. Preferably, the weld strength of the weak area V is approximately 10 kgf / cm². 2 The following is possible. Preferably, the weld strength of the weak point V is approximately 0 kgf / cm 2 It can exceed a certain value.

[0082] As shown in Figure 6, the vulnerable portion V may be provided between all of the multiple housing joints 32 and the inner surface of the battery housing 20. In this case, as in the embodiment shown in Figure 8, if a thermal event occurs and the internal pressure of the battery housing 20 reaches a reference value or higher, the entire first current collector 30 may be separated from the battery housing 20.

[0083] According to the above embodiment of the present invention, when a thermal event occurs, the entire first current collector 30 is completely separated from the battery housing 20 and the opening is opened, allowing the electrode assembly 10 to be discharged more easily through the opening. As a result, according to the above embodiment of the present invention, when a thermal event occurs, the heat and pressure inside the battery housing 20 can be smoothly discharged to the outside of the battery housing 20.

[0084] Unlike the above embodiment, only a portion of the multiple welds W provided between all of the multiple housing joints 32 and the inner surface of the battery housing 20 may be provided as a weak point V. That is, the bonding strength between each housing joint 32 and the inner surface of the battery housing 20 may be configured to be different from each other. In such a case, when a thermal event occurs, only a portion of the first current collector 30 may separate from the battery housing 20 and the opening may be opened.

[0085] Referring to Figures 6 and 7, the welds W formed between the inner surface of the battery housing 20 and the multiple housing joints 32 can be formed in multiple locations within the same housing joint 32. In this case, the multiple welds W can form a predetermined welding pattern. The number of welds W formed within one housing joint 32 can be configured to differ for each of the multiple housing joints 32. In other words, the bonding strength between each housing joint 32 and the inner surface of the battery housing 20 can be configured to differ from one another. That is, the bonding strength between some of the multiple housing joints 32 and the inner surface of the battery housing 20 can be configured to be weaker than the bonding strength between the remaining housing joints 32 and the inner surface of the battery housing 20.

[0086] For example, four housing couplings 32 may be provided, with three welds W between two of the four housing couplings 32 and the inner surface of the battery housing 20, and two welds W between the remaining two housing couplings 32 and the inner surface of the battery housing 20. This allows the coupling strength between the remaining two housing couplings 32 and the inner surface of the battery housing 20 to be weaker. In such a case, when a thermal event occurs, only a portion of the first current collector 30 may separate from the battery housing 20, and the opening may be opened.

[0087] On the other hand, referring to Figure 7, the battery housing 20 may include a beading portion 21. The beading portion 21 may be formed on the upper part of the electrode assembly 10. The beading portion 21 may be formed at the end of the battery housing 20 adjacent to the opening and have a form that is press-fitted inward. More specifically, the beading portion 21 may be provided in the region between the opening formed on one side of the battery housing 20 and the housing portion that accommodates the electrode assembly 10. The beading portion 21 may have a shape that is press-fitted around the outer circumferential surface of the battery housing 20 to a predetermined depth. The vertical distance from the inner surface of the battery housing 20 to the innermost point of the beading portion 21 can be defined as the press-fitting depth PD. As a result, the inner diameter of the battery housing 20 in the region where the beading portion 21 is formed may be smaller than the diameter of the electrode assembly 10.

[0088] The beading portion 21 prevents the electrode assembly 10, which has a size approximately corresponding to the inner diameter of the battery housing 20, from falling out of the opening formed at the upper end of the battery housing 20, and can also function as a support portion on which the first current collector 30 sits. The beading portion 21 can also function as a support portion for fixing not only the first current collector 30, but also the housing cover 40 or sealing gasket G1, which will be described later.

[0089] If a beading portion 21 is formed in the battery housing 20, the housing coupling portion 32 may be coupled onto the beading portion 21. In this case, the contact portion 32a may be welded onto the beading portion 21. That is, the welded portion W may be provided between the beading portion 21 and at least one of the multiple housing coupling portions 32. Both the beading portion 21 and the contact portion 32a may have a shape that extends along a direction substantially parallel to the bottom surface of the battery housing 20, that is, a direction substantially perpendicular to the side wall of the battery housing 20.

[0090] According to the above embodiment of the present invention, when the housing coupling portion 32 is coupled to the beading portion 21, the coupling force between the housing coupling portion 32 and the beading portion 21 can be increased, and the resistance reduction effect can be improved by increasing the contact area.

[0091] The beading portion 21 may have a flat section F parallel to the bottom surface of the battery housing 20 in at least a portion of its area. The flat section F may be formed on the upper surface of the beading portion 21. The housing coupling portion 32, i.e., the contact portion 32a, may be welded onto this flat section F.

[0092] The length of the flat section F of the beading portion 21 that contacts the first current collector 30 can be OV-R1. Referring to Figure 7, the shortest distance from the end of the contact portion 32a to the perpendicular line passing through the innermost point of the beading portion 21 can be defined as the overlap length OV. The length of the flat section F may correspond to the length obtained by subtracting the radius of curvature R1 of the beading portion 21 from this overlap length OV. The welding area between the contact portion 32a and the beading portion 21 may be formed to be narrower than the length of the flat section F.

[0093] The radial width WD of the weld W may be set to 20% or less of the length of the flat section F. If the ratio satisfies the range, the weld strength between the first current collector 30 and the beading portion 21 of the battery housing 20 may decrease. This allows the first current collector 30 to be quickly separated from the battery housing 20 if a thermal event occurs in the battery cell 1, and the electrode assembly 10 to be smoothly discharged to the outside of the battery housing 20. This minimizes heat and pressure inside the battery housing 20 and ensures the thermal stability of the battery cell 1.

[0094] Figure 9 is a plan view of a battery cell according to another embodiment of the present invention, and Figure 10 is a cross-sectional view showing a state in which a part of the first current collector included in a battery cell according to one embodiment of the present invention is coupled to the battery housing. Figure 11 is a cross-sectional view showing a state in which a part of the first current collector included in a battery cell according to one embodiment of the present invention is separated from the battery housing when a thermal event occurs.

[0095] The welded portion W may be provided on only a portion of the multiple housing joints 32. For example, as shown in Figures 9 and 10, if there are four housing joints 32, the welded portion W may be provided only between one of the four housing joints 32 and the inner surface of the battery housing 20. The total number of housing joints 32 and the number of welded portions W may be configured differently from those in the above embodiment.

[0096] In such a case, as shown in the embodiment in Figure 11, when a thermal event occurs, only a part of the first current collector 30, that is, the housing joint portion 32 where the welded portion W is not provided, is separated from the battery housing 20, and the opening can be opened. As a result, according to the above embodiment of the present invention, when a thermal event occurs in the battery cell 1, a part of the first current collector 30 is quickly separated from the battery housing 20, and the electrode assembly 10 can be smoothly discharged to the outside of the battery housing 20. This minimizes the heat and pressure inside the battery housing 20 and ensures the thermal stability of the battery cell 1.

[0097] Referring to Figures 1, 3, and 4, etc., a battery cell 1 according to one embodiment of the present invention may further include a housing cover 40. The housing cover 40 may be configured to seal an opening formed on one side of the battery housing 20. The housing cover 40 may be fixed by a crimping portion 22 formed on the upper end of the battery housing 20. In this case, a sealing gasket G1 may be interposed between the battery housing 20 and the housing cover 40, and between the current collector 30 and the housing cover 40, in order to improve the fixing force and the airtightness of the battery housing 20.

[0098] The beading portion 21 can provide a support surface on which the housing cover 40 can be seated. The upper surface of the beading portion 21 may have a shape that extends along a direction substantially parallel to the bottom surface of the battery housing 20, that is, a direction substantially perpendicular to the side wall of the battery housing 20, in order to stably support the peripheral edge of the housing cover 40.

[0099] On the other hand, the battery housing 20 may further include a crimping portion 22. The crimping portion 22 may be formed on the upper part of the beading portion 21. The crimping portion 22 may have a folded shape that extends to surround the peripheral edge of the housing cover 40, which is positioned above the beading portion 21. The shape of such a crimping portion 22 allows the housing cover 40 to be fixed onto the beading portion 21. Of course, it is also possible to omit this crimping portion 22 and configure the housing cover 40 to cover and fix the opening of the battery housing 20 by other fixing structures.

[0100] The housing cover 40 may include a vent portion 41 formed to prevent an increase in internal pressure due to gas generated inside the battery housing 20. The vent portion 41 may be configured to rupture if the internal pressure of the battery housing 20 rises above a reference value. For example, the vent portion 41 may be formed in a part of the housing cover 40 and may be a structurally weaker area than the surrounding area so as to rupture easily when internal pressure is applied. The vent portion 41 may be a thinner area compared to the surrounding area, for example. Referring to Figures 1 and 3, the vent portion 41 may form a substantially circular closed loop.

[0101] According to the above embodiment of the present invention, as shown in Figures 4, 8, and 11, when the internal pressure of the battery housing 20 rises above a reference value due to a thermal event, the vent portion 41 ruptures, and at least a part of the first current collector 30 can be separated from the battery housing 20. In this case, only the connection portion 32b, the first plain portion connecting portion 31, and the support portion 33 can be discharged through the vent portion 41. As a result, the first current collector 30 can take on a shape that is inverted vertically from its normal state. According to the above embodiment of the present invention, when the first current collector 30 is separated from the electrode assembly 10 and inverted, high-temperature heat and pressure can be discharged through the vent portion 41.

[0102] On the other hand, referring to Figure 3, terminal 50 may be electrically connected to the second blank portion 12 of the electrode assembly 10 by passing through the battery housing 20 on the side opposite to the opening of the battery housing 20. Terminal 50 may pass through approximately the center of the bottom surface of the battery housing 20.

[0103] On the other hand, in the present invention, the outer surface 20a of the closing portion located on the opposite side of the opening provided at the upper end of the battery housing 20 can function as a first electrode terminal T1. If the first blank portion 11 is a negative electrode tab, the first electrode terminal T1 can become a negative electrode terminal.

[0104] The battery cell 1 according to the present invention has a structure in which the terminal 50 exposed on the bottom surface located opposite the opening of the battery housing 20 can be used as the second electrode terminal T2, and the remaining area of ​​the bottom surface of the battery housing 20, excluding the area occupied by the terminal 50 (including the area where the insulating gasket G2 is exposed on the outer surface 20a of the closing part and outside the terminal 50), can be used as the first electrode terminal T1.

[0105] Therefore, the battery cell 1 according to the present invention simplifies the electrical connection structure because, when electrically connecting multiple battery cells 1, both the positive and negative electrodes can be connected from one direction. Furthermore, the battery cell 1 according to the present invention has a structure in which most of the bottom surface located on the opposite side of the opening of the battery housing 20 can be used as electrode terminals, which has the advantage of providing sufficient area for welding electrical connection components.

[0106] Figure 12 shows a second current collector included in a cylindrical battery cell according to one embodiment of the present invention.

[0107] Referring to Figure 1 and Figure 12, the second current collector 60 may be coupled to the lower part of the electrode assembly 10. The second current collector 60 includes a conductive metallic material and may be electrically coupled to the second blank portion 12. The second current collector 60 may be coupled to a coupling surface (bent surface) formed by bending the end of the second blank portion 12 in a direction parallel to the current collector 60. This is the same as in the case of the first blank portion 11 described above.

[0108] The second current collector 60 may include a peripheral portion 61 and a second plain portion connecting portion 62. The peripheral portion 61 is located at the bottom of the electrode assembly 10 and may have a substantially rim shape with a space formed inside it.

[0109] Figure 12 of the present invention shows only the case where the peripheral edge 61 has a substantially circular rim shape, but the present invention is not limited thereto. The peripheral edge 61 may have a substantially square rim shape, a hexagonal rim shape, an octagonal rim shape, or other rim shapes, unlike the illustrated example.

[0110] The second plain section joining portion 62 extends inward from the peripheral portion 61 and can be joined to the second plain section 12.

[0111] On the other hand, terminal 50 can be electrically connected to electrode assembly 10, for example, by connecting to a second current collector 60 connected to the second blank portion 12, or by connecting to a lead tab (not shown) connected to the second blank portion 12.

[0112] In this case, the current collector (second current collector) 60 may include a terminal coupling portion 63. The terminal coupling portion 63 may be provided at a distance from the second plain portion coupling portion 62. The terminal coupling portion 63 may be located inside the peripheral portion 61. The terminal coupling portion 63 may be joined to the terminal 50 by welding. The terminal coupling portion 63 may have a diameter substantially the same as, or larger than, the diameter of the flat portion formed on the bottom surface of the terminal 50 in order to secure a welding area for joining with the flat portion formed on the bottom surface of the terminal 50. The terminal coupling portion 63 may be located, for example, in the approximate center of the inner space surrounded by the peripheral portion 61. The terminal coupling portion 63 may be positioned in a location corresponding to the winding hole H1 formed in the core portion of the electrode assembly 10.

[0113] The second blank section coupling portion 62 and the terminal coupling portion 63 are not directly connected but are spaced apart from each other and are electrically connected by the peripheral portion 61. Thus, the current collector 60 of the present invention has a structure in which the blank section coupling portion 62 and the terminal coupling portion 63 are not directly connected but are indirectly connected via the peripheral portion 61. This allows the impact applied to the coupling portion between the blank section coupling portion 62 and the second blank section 12, and the coupling portion between the terminal coupling portion 63 and the terminal 50, when the battery cell 1 is subjected to shock and / or vibration, to be dispersed. Therefore, the current collector 60 of the present invention can minimize or prevent damage to the welded portion due to external impact.

[0114] The current collector 60 may further include a bridge portion 64 that extends inward from the peripheral portion 61 and is connected to the terminal coupling portion 63.

[0115] Multiple second plain section connecting sections 62 and / or bridge sections 64 may be provided. The number of second plain section connecting sections 62 and / or bridge sections 64 may be determined by considering the required resistance level of the battery cell 1, the required aperture ratio of the current collector 60, and so on.

[0116] On the other hand, the second blank portion 12 and / or the second current collector 60 can maintain an insulated state from the battery housing 20. For this purpose, an insulator 70 may be interposed between the second blank portion 12 and the battery housing 20 and / or between the second current collector 60 and the battery housing 20. If the insulator 70 is applied, the terminal 50 may pass through the insulator 70 for electrical connection with the second blank portion 12.

[0117] Figure 13 is a diagram showing a schematic configuration of a battery pack including a cylindrical battery cell according to one embodiment of the present invention.

[0118] Referring to Figure 13, a battery pack 3 according to one embodiment of the present invention may include a battery cell assembly in which a plurality of battery cells 1 according to the above embodiment of the present invention are electrically connected, and a pack housing 2 that houses the same.

[0119] Multiple battery cells 1 can be housed in the pack housing 2 with the vent portion 41 facing downwards. According to the above embodiment of the present invention, when the battery pack 3 is mounted in an automobile or the like, it is possible to prevent the electrode assembly 10 that is ejected when a thermal event occurs in the battery cell 1 from moving towards the driver who is located above.

[0120] On the other hand, the battery pack 3 according to one embodiment of the present invention may further include components such as busbars for electrical connection, a cooling unit, and power terminals, but these are omitted from the drawing for convenience.

[0121] Figure 14 shows a schematic configuration of an automobile including a battery pack according to one embodiment of the present invention.

[0122] Referring to Figure 14, the automobile 5 according to one embodiment of the present invention may be, for example, an electric vehicle, a hybrid vehicle, or a plug-in hybrid vehicle, and includes a battery pack 3 according to one embodiment of the present invention. The automobile 5 may include four-wheeled vehicles and two-wheeled vehicles. The automobile 5 may be powered by the battery pack 3 according to one embodiment of the present invention.

[0123] Although preferred embodiments of the present invention have been illustrated and described above, the present invention is not limited to the specific embodiments described above, and it goes without saying that various modifications can be made by persons with ordinary skill in the art to which the invention belongs without departing from the gist of the invention claimed in the claims, and these modifications should not be understood individually from the technical idea or prospects of the present invention. [Explanation of symbols]

[0124] 1. Battery cell, cylindrical battery 2-pack housing 3 Battery Packs 5. Automobile 10 Electrode assembly 11. First blank section 11a Split piece 12. Second blank section 20 Battery Housing 20a Exterior 21 Beading section 22 Crimping section 30. First current collector 31. First plain section joining part 32 Housing joint 32a Contact part 32b Connection section 33 Support part 40 Housing Cover 41 Vent section 50 terminals 60 Second current collector 61 Peripheral area 62 Second plain section joining part 63 Terminal connection part 64 Bridge section 70 Insulators F Flat section G1 Sealing Gasket G2 Insulating Gasket H1 winding hole H2 Current collector hole H3 liquid injection hole OV overlap length R1 radius of curvature T1 1st electrode terminal T2 2nd electrode terminal V Weak part W Weld WD Radial width

Claims

1. An electrode assembly comprising a first electrode having a first blank portion, a second electrode having a second blank portion, and a separator interposed between them, A battery housing configured to accommodate the electrode assembly through an opening provided on one side, A first current collector is provided on the opening side and configured to electrically connect the first blank portion and the battery housing, Includes, The first current collector is configured such that at least a portion of it separates from the battery housing when the internal pressure rises above a reference value, in a battery cell.

2. A welded portion is formed between the first current collector and the inner surface of the battery housing, and at least a portion of the first current collector is welded to the inner surface of the battery housing, as described in claim 1.

3. The first current collector is A first blank portion connecting portion is positioned on the upper part of the electrode assembly and connected to the first blank portion, Multiple housing coupling portions are arranged on the inner surface of the battery housing, Includes, The battery cell according to claim 2, wherein at least one welded portion is provided between at least one of the plurality of housing joints and the inner surface of the battery housing.

4. The first current collector is The electrode assembly further includes a support portion positioned on the upper part of the electrode assembly, The battery cell according to claim 3, wherein the first plain portion connecting portion and the plurality of housing connecting portions are formed extending from the support portion.

5. Each of the aforementioned multiple housing joints is, A contact portion welded to the inner surface of the battery housing, A connecting portion that connects the support portion and the contact portion, The battery cell according to claim 4, including the battery cell described in claim 4.

6. The battery cell according to claim 5, wherein the contact portions are provided spaced apart from each other along the circumferential direction of the electrode assembly.

7. The battery cell according to claim 3, wherein the welded portion is provided for each of the plurality of housing joints.

8. The battery cell according to claim 7, wherein the welded portion includes a weak portion with low welding strength.

9. The welding strength of the aforementioned weak point is approximately 10 kgf / cm². ２ The battery cell according to claim 8, which is as follows:

10. The battery cell according to claim 7, wherein the welded portion formed between the inner surface of the battery housing and the plurality of housing joints is formed in multiple locations within the same housing joint.

11. The battery cell according to claim 10, wherein the number of welded portions formed within one housing joint is configured to differ for each of the plurality of housing joints.

12. The battery housing includes a beading portion formed at the end adjacent to the opening and press-fitted inward, The battery cell according to claim 7, wherein the welded portion is provided between the beading portion and the plurality of housing joint portions.

13. The beading portion has a flat section parallel to the bottom surface of the battery housing in at least a portion of the area. The battery cell according to claim 12, wherein the radial width of the welded portion is set to be 20% or less of the length of the flat section.

14. The battery cell according to claim 3, wherein the welded portion is provided only on a portion of the plurality of housing joint portions.

15. The battery cell according to claim 1, further comprising a housing cover configured to seal the opening and having a vent portion.

16. The battery cell according to claim 1, further comprising a terminal on the opposite side of the opening that penetrates the battery housing and is electrically connected to the second blank portion.

17. The present invention further includes a second current collector located between the electrode assembly and the terminal, The second current collector is The second plain section joining section is joined to the second plain section, A terminal coupling portion connected to the aforementioned terminal, The battery cell according to claim 16, including the battery cell according to claim 16.

18. A battery pack comprising a plurality of battery cells as described in any one of claims 1 to 17.

19. An automobile comprising the battery pack described in claim 18.

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