Cylindrical battery cell, and battery pack and automobile including the same

Abstract

A cylindrical battery cell according to an embodiment of the present invention includes an electrode assembly having a first electrode tab having a first polarity and a second electrode tab having a second polarity; a battery can having an open portion formed at a lower end and a closed portion formed at an upper end, the battery can receiving the electrode assembly through the open portion and electrically connected to the second electrode tab; a cell terminal electrically connected to the first electrode tab, exposed to an outside of the battery can through the closed portion of the battery can and electrically insulated from the battery can; a first current collecting plate having a first surface and a second surface opposite to the first surface, the first surface being coupled to the first electrode tab and the second surface being coupled to the cell terminal; and a terminal fastening member mechanically fastening the cell terminal and the first current collecting plate.

Description

[Technical Field]

[0001] The present invention relates to a cylindrical battery cell, a battery pack including the same, and a vehicle. More particularly, the present invention relates to a cylindrical battery cell having a structure in which both a positive electrode terminal and a negative electrode terminal are disposed adjacent to one side of the cylindrical battery cell, without significantly modifying the structure of a conventional cylindrical battery cell, and a battery pack and a vehicle including the same.

[0002] This application claims priority based on Korean Patent Application No. 10-2022-0029614, filed on March 8, 2022, the entire contents of which are incorporated herein by reference in their entirety in the specification and drawings thereof. [Background technology]

[0003] Secondary batteries, which are easy to apply to various products and have electrical properties such as high energy density, are widely used not only in portable devices but also in electric vehicles (EVs) and hybrid electric vehicles (HEVs), which are powered by electric sources.

[0004] Such secondary batteries have the main advantage of dramatically reducing the use of fossil fuels, as well as the advantage of not producing any by-products from energy use, and are therefore attracting attention as a new energy source that is environmentally friendly and improves energy efficiency.

[0005] Currently widely used types of secondary batteries include lithium-ion batteries, lithium polymer batteries, nickel-cadmium batteries, nickel-metal hydride batteries, and nickel-zinc batteries. The operating voltage of such a unit secondary battery cell is approximately 2.5V to 4.5V. Therefore, if a higher output voltage is required, a battery pack is constructed by connecting multiple battery cells in series. Alternatively, a battery pack may be constructed by connecting multiple battery cells in parallel depending on the required charge / discharge capacity of the battery pack. Therefore, the number of battery cells included in the battery pack and the type of electrical connection can be variously set depending on the required output voltage and / or charge / discharge capacity.

[0006] Meanwhile, cylindrical, prismatic, and pouch-type battery cells are known as secondary battery cell types. In the case of cylindrical battery cells, an insulating separator is interposed between a positive electrode and a negative electrode, and the resulting jelly-roll-like electrode assembly is rolled up. This jelly-roll-like electrode assembly is then inserted into a battery can together with an electrolyte to form a battery. Furthermore, strip-shaped electrode tabs may be connected to the uncoated portions of the positive and negative electrodes, and the electrode tabs electrically connect the electrode assembly to electrode terminals exposed to the outside. For example, the positive electrode terminal is a cap plate of a seal that seals the opening of the battery can, and the negative electrode terminal is the battery can.

[0007] However, conventional cylindrical battery cells with this structure have problems such as high resistance, heat generation, and poor current collection efficiency because current concentrates on the strip-shaped electrode tabs connected to the positive electrode uncoated region and / or the negative electrode uncoated region.

[0008] Small cylindrical battery cells with 18650 or 21700 form factors do not pose significant resistance and heat generation issues. However, when cylindrical battery cells are enlarged in form factor for application in electric vehicles, excessive heat is generated around the electrode tabs during fast charging, which can cause the cylindrical battery cell to catch fire. Therefore, to solve these issues, the development of battery cells with improved structures is required.

[0009] Furthermore, the battery pack installed in the electric vehicle includes a plurality of cylindrical battery cells, and therefore, the inefficiency of electrical wiring causes significant inconvenience during the assembly process of the electric vehicle and during maintenance of the battery pack.

[0010] Meanwhile, as cylindrical battery cells are recently applied to electric vehicles, the form factor of cylindrical battery cells is increasing. That is, the diameter and height of cylindrical battery cells are increasing compared to cylindrical battery cells with conventional form factors such as 18650 and 21700. The increase in form factor increases energy density, improves safety against thermal runaway, and improves cooling efficiency.

[0011] The energy density of cylindrical battery cells can be further increased by increasing the form factor and minimizing unnecessary space inside the battery can. Therefore, components used for electrical insulation between the electrode assembly and the battery can, as well as components used for collecting current from the positive and negative plates, must be optimally designed to increase the capacity of the battery cell and reduce the overall resistance of the battery cell. Summary of the Invention [Problem to be solved by the invention]

[0012] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a cylindrical battery cell having a structure in which a positive electrode terminal and a negative electrode terminal are applied in the same direction.

[0013] An object of the present invention is to ensure a sufficient area for welding electrical connection parts such as bus bars used to manufacture a battery pack to the electrode terminals of the cylindrical battery cells by making it possible to utilize the wide surface of the closing part of the battery can as an electrode terminal when electrically connecting multiple cylindrical battery cells in one direction.

[0014] In another aspect, an object of the present invention is to improve the processability when joining a current collector plate (first current collector plate) and a cell terminal, and to reduce the resistance at the joining site.

[0015] In another aspect, an object of the present invention is to optimally design the area occupied by the upper surface of the cell terminal (first electrode terminal) and the area occupied by the outer surface of the closure part (second electrode terminal) so that they are sufficient for coupling with the bus bar.

[0016] In another aspect, the present invention aims to minimize the resistance of a cylindrical battery cell by improving the uncoated portion structure of the electrode assembly to increase the contact area between the electrode assembly and the current collector plate (first current collector plate) and / or the contact area between the cell terminal and the current collector plate (first current collector plate).

[0017] In another aspect, the present invention aims to minimize the resistance of a cylindrical battery cell by improving the electrical connection structure between a current collector plate (second current collector plate) and a battery can to multiplex current paths and maximize the contact area.

[0018] In another aspect, the present invention aims to improve the electrical connection structure between the current collector plate (second current collector plate) and the battery can to reduce the current path, thereby minimizing the resistance of the cylindrical battery cell.

[0019] In another aspect, the present invention aims to minimize dead space by improving the uncoated portion structure of the electrode assembly and / or optimizing the height of the cell terminal and / or optimizing the thickness of the battery can, thereby maximizing energy density.

[0020] However, the technical problems that the present invention aims to solve are not limited to those mentioned above, and other problems not mentioned will become clear to those skilled in the art from the following description of the invention. [Means for solving the problem]

[0021] According to one embodiment of the present invention, there is provided a cylindrical battery cell including: an electrode assembly including a first electrode tab having a first polarity and a second electrode tab having a second polarity; a battery can having an opening formed at a lower end and a closing portion formed at an upper end, the battery can receiving the electrode assembly through the opening and electrically connected to the second electrode tab; a cell terminal electrically connected to the first electrode tab, exposed to the outside of the battery can through the closing portion of the battery can, and electrically insulated from the battery can; a first current collector plate having a first surface and a second surface opposite to the first surface, the first surface coupled to the first electrode tab and the second surface coupled to the cell terminal; and a terminal fastening member that mechanically fastens the cell terminal to the first current collector plate.

[0022] The terminal fastening member may be press-fitted into the inside of the first current collector plate and the cell terminal to fasten the cell terminal and the first current collector plate together.

[0023] The terminal fastening member may include a base portion and a fastening portion extending from the base portion toward the first current collector plate and press-fitted from a surface of the first current collector plate into the inside of the first current collector plate and the cell terminal.

[0024] The cell terminal and the first current collector plate may include aluminum.

[0025] The terminal fastener may include boron steel containing 0.001 wt% to 0.008 wt% boron.

[0026] At least a portion of the first current collector plate can be pressed into the cell terminal by press-fitting the fastening portion on the outside and inside of the fastening portion.

[0027] The terminal fastening member may have a maximum diameter or width smaller than the diameter of a central hole of the electrode assembly.

[0028] The cylindrical battery cell may further include a cap plate that seals the open portion of the battery can.

[0029] The cap plate may not be electrically connected to the electrode assembly and thus may not have polarity.

[0030] The cylindrical battery cell may further include a second current collector plate electrically connecting the second electrode tab and the battery can.

[0031] The second current collector plate may include a tab coupling portion coupled to the second electrode tab and a can coupling portion electrically coupled to the battery can.

[0032] The can coupling portion may be electrically coupled to an inner surface of the sidewall of the battery can.

[0033] The battery can may include a bead portion formed by press-fitting the periphery of the outer periphery of the battery can at the opening side, and the can coupling portion may be electrically coupled to a lower surface of the bead portion.

[0034] Meanwhile, a battery pack according to an embodiment of the present invention includes a plurality of cylindrical battery cells.

[0035] An automobile according to one embodiment of the present invention includes the battery pack. [Effects of the Invention]

[0036] According to one aspect of the present invention, the processability of bonding a current collector plate (first current collector plate) to a cell terminal can be improved, and the resistance at the bonding site can be reduced.

[0037] According to another aspect of the present invention, the electrode terminal structure of a cylindrical battery cell is improved to increase space efficiency within a battery can, thereby reducing the internal resistance of the cylindrical battery cell and increasing its energy density.

[0038] According to another aspect of the present invention, the electrode terminal structure of a cylindrical battery cell is improved to increase the cross-sectional area of ​​the current path, thereby alleviating the problem of internal heat generation that occurs during fast charging.

[0039] According to another aspect of the present invention, electrical wiring for connecting cylindrical battery cells in series and / or in parallel can be performed on one side of the cylindrical battery cells.

[0040] According to another aspect of the present invention, when attempting to electrically connect multiple cylindrical battery cells in one direction, a wide surface of the closing portion of the battery can can be used as an electrode terminal, thereby ensuring a sufficient area for welding an electrical connection component, such as a bus bar for manufacturing a battery pack, to the electrode terminal of the cylindrical battery cell.

[0041] According to another aspect of the present invention, the area occupied by the upper surface of the cell terminal (first electrode terminal) and the area occupied by the outer surface of the closure part (second electrode terminal) can be optimally designed to be sufficient for coupling with the bus bar.

[0042] According to another aspect of the present invention, by improving the uncoated portion structure of the electrode assembly, the contact area between the electrode assembly and the current collector plate (first current collector plate) and / or the contact area between the cell terminal and the current collector plate (first current collector plate) can be increased, thereby minimizing the resistance of the cylindrical battery cell.

[0043] According to another aspect of the present invention, the electrical connection structure between the current collector plate (second current collector plate) and the battery can is improved to multiplex the current path, thereby maximizing the contact area between these components and minimizing the resistance of the cylindrical battery cell.

[0044] According to another aspect of the present invention, the electrical connection structure between the current collector plate (second current collector plate) and the battery can is improved to reduce the current path, thereby minimizing the resistance of the cylindrical battery cell.

[0045] According to another aspect of the present invention, the dead space can be minimized by improving the uncoated portion structure of the electrode assembly and / or optimizing the height of the cell terminal and / or optimizing the thickness of the battery can, thereby maximizing the energy density.

[0046] According to yet another aspect of the present invention, a battery pack manufactured using cylindrical battery cells having an improved structure, and a vehicle including the same, can be provided.

[0047] The following drawings attached to this specification illustrate preferred embodiments of the present invention and serve to further understand the technical concept of the present invention as well as the content of the invention, and therefore the present invention should not be interpreted as being limited to the matters depicted in the drawings. [Brief explanation of the drawings]

[0048] [Figure 1] 1 is a perspective view illustrating an external appearance of a cylindrical battery cell according to an embodiment of the present invention; [Figure 2] 1 is a perspective view of an electrode assembly in which a non-coating portion is bent according to an embodiment of the present invention; [Figure 3] 1 is a cross-sectional view showing an internal structure of a cylindrical battery cell according to an embodiment of the present invention. [Figure 4]1A and 1B are a partial cross-sectional view showing an upper structure of a cylindrical battery cell according to an embodiment of the present invention and a partial enlarged view showing an area where a fastening member is applied; [Figure 5] 1 is a cross-sectional view of a cylindrical battery cell according to an embodiment of the present invention, illustrating a process of connecting a first current collector plate and a cell terminal using a fastening member. FIG. [Figure 6] 4A to 4C are conceptual diagrams for explaining the steps of joining the first current collector plate and the cell terminal using fastening members. [Figure 7] FIG. 2 is a diagram showing a first current collecting plate according to one embodiment of the present invention. [Figure 8] FIG. 2 is a partial cross-sectional view showing a lower structure of a cylindrical battery cell according to an embodiment of the present invention. [Figure 9] FIG. 2 is a plan view showing the bottom surface of a cylindrical battery cell according to an embodiment of the present invention. [Figure 10] FIG. 1 is a top plan view illustrating a state in which a plurality of cylindrical battery cells are connected in series and in parallel using bus bars according to an embodiment of the present invention. [Figure 11] 1 is a diagram showing a schematic configuration of a battery pack including a cylindrical battery cell according to an embodiment of the present invention; [Figure 12] 1 is a diagram showing a schematic configuration of a vehicle including a battery pack according to an embodiment of the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0049] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, the terms and words used in this specification and claims should not be construed as being limited to their ordinary and dictionary meanings, but should be construed as meanings and concepts corresponding to the technical ideas of the present invention, based on the principle that the inventors themselves can appropriately define the concepts of terms in order to best describe the invention. Therefore, it should be understood that the configurations shown in the embodiments described in this specification are merely the most preferred embodiment of the present invention and do not represent the entire technical ideas of the present invention, and therefore various equivalents and modifications that can be substituted therefor may exist at the time of filing this application.

[0050] In order to facilitate understanding of the invention, the accompanying drawings may not be drawn to scale, and the dimensions of some components may be exaggerated. In addition, the same reference numerals may be used to refer to the same components in different embodiments.

[0051] A statement that two comparison objects are identical means that they are "substantially identical." Therefore, "substantially identical" can include cases where there is a deviation that is considered to be a low level in the art, for example, a deviation within 5%. Furthermore, in a given region, uniformity of a certain parameter can mean uniformity on average.

[0052] 1 to 4, the cylindrical battery cell 1 according to the embodiment of the present invention includes an electrode assembly 10, a battery can 20, a cell terminal 40, a first current collector plate 50, and a terminal fastening member 60. In addition to the above-mentioned components, the cylindrical battery cell 1 may further include a cap plate 30 and / or an insulator 70, and / or an insulating gasket G1 and / or a sealing gasket G2 and / or a second current collector plate 80.

[0053] The electrode assembly 10 includes a first electrode tab 11 having a first polarity and a second electrode tab 12 having a second polarity. The first electrode tab 11 and the second electrode tab 12 may have shapes that extend in opposite directions along the height direction (direction parallel to the Z axis) of the electrode assembly 10. For example, the first electrode tab 11 may have a shape that extends upward, and the second electrode tab 12 may have a shape that extends downward. That is, the first electrode tab 11 may extend toward a closed portion located opposite an open portion formed at the bottom end of the battery can 20, and the second electrode tab 12 may extend toward the open portion of the battery can 20.

[0054] The electrode assembly 10 includes a first electrode having a first polarity, a second electrode having a second polarity, and a separator interposed between the first and second electrodes. The first electrode is a positive or negative electrode, and the second electrode has the opposite polarity to the first electrode.

[0055] The electrode assembly 10 may have, for example, a jelly-roll structure. That is, the electrode assembly 10 may be manufactured by stacking substantially sheet-shaped first and second electrodes at least once with a separator interposed therebetween, and then winding the stack around a core portion. A central hole C may be formed in the core portion of the wound electrode assembly 10. An additional separator may be provided on the outer periphery of the electrode assembly 10 to insulate it from the battery can 20. Any jelly-roll structure known in the art may be applied to the present invention without limitation.

[0056] The first electrode includes a first electrode collector and a first electrode active material coated on one or both sides of the first electrode collector. A first uncoated portion, where the first electrode active material is not coated, is present at one end of the first electrode collector in its width direction (parallel to the Z-axis). The first uncoated portion, which functions as an electrode tab, is hereinafter referred to as a first electrode tab 11. The first electrode tab 11 is provided at the upper portion in the height direction (parallel to the Z-axis) of the electrode assembly 10 housed in the battery can 20. That is, the first electrode collector has a first uncoated portion, i.e., a portion where the active material layer is not coated, formed at one end of the first electrode collector in its width direction (parallel to the Z-axis) and extending along its length direction (parallel to the X-axis). This first uncoated portion is exposed to the outside of the separator. The first uncoated portion itself serves as an electrode tab. The first electrode tab 11 may be, for example, a positive electrode tab.

[0057] Referring to the exemplary embodiment of the electrode assembly 10 of the present invention shown in FIG. 2, at least a portion of the first electrode tab 11 may include a plurality of segments 11a separated along the winding direction of the electrode assembly 10. In this case, the segments 11a are folded along the radial direction of the electrode assembly 10. The folded segments 11a may overlap each other in multiple layers. In this case, a first tab coupling portion 52 of a first current collector plate 50, which will be described later, may be coupled to a region where the segments 11a overlap each other in multiple layers. Meanwhile, the electrode assembly 10 may include a uniform layer count region, which is a region where the number of overlapping layers of the segments 11a of the first electrode tab 11 is maintained at a substantially maximum value along the radial direction of the electrode assembly 10. Because the number of overlapping layers is maximized in this region, it may be advantageous to perform welding between the first current collector plate 50 and the first electrode tab 11, which will be described later, in this region. This is to prevent the laser beam from penetrating the first electrode tab 11 and damaging the electrode assembly 10 when the laser output is increased to improve welding quality, for example, when laser welding is applied. Also, this is to effectively prevent foreign matter such as welding spatter from entering the inside of the electrode assembly 10.

[0058] The second electrode includes a second electrode current collector and a second electrode active material coated on one or both sides of the second electrode current collector. A second uncoated portion, where the second electrode active material is not coated, is present at the other end of the second electrode current collector in the width direction (direction parallel to the Z axis). The second uncoated portion, which functions as an electrode tab, is hereinafter referred to as the second electrode tab 12. The second electrode tab 12 is provided at the lower portion in the height direction (direction parallel to the Z axis) of the electrode assembly 10 housed in the battery can 20. That is, the second electrode current collector has a second uncoated portion, i.e., a portion where the active material layer is not coated, formed at the other end of the second electrode current collector in the width direction (direction parallel to the Z axis) and extending along its length direction (direction parallel to the X axis), and this second uncoated portion is exposed to the outside of the separator. The second electrode tab 12 may be, for example, a negative electrode tab.

[0059] Meanwhile, similar to the first electrode tab 11 described above, at least a portion of the second electrode tab 12 may include a plurality of segments separated along the winding direction of the electrode assembly 10. In this case, the segments are folded along the radial direction of the electrode assembly 10. The folded segments may overlap in multiple layers. In this case, the second tab coupling portion 82 of the second current collector plate 80, described below, may be coupled to a region where the segments overlap in multiple layers. Meanwhile, the electrode assembly 10 may have a uniform layer count region, which is a region where the number of overlapping layers of the segments of the second electrode tab 12 remains constant at a substantially maximum value along the radial direction of the electrode assembly 10. Because the number of overlapping layers is maximized in this region, it may be advantageous to perform welding between the second current collector plate 80 and the second electrode tab 12, described below, within this region. This is to prevent the laser beam from penetrating the second electrode tab 12 and damaging the electrode assembly 10 when increasing the laser output to improve welding quality, for example, when applying laser welding. This is also to effectively prevent foreign matter such as welding spatter from entering the inside of the electrode assembly 10.

[0060] 3, 4, and 8, the battery can 20 is a generally cylindrical container having an opening at the bottom and an empty space therein, and is made of a conductive material such as metal. Examples of materials for the battery can 20 include steel, stainless steel, and nickel-plated iron. Using an iron-based material with excellent rigidity can be advantageous in terms of the rigidity of the battery can 20. In particular, the rigidity of the battery can 20 needs to be sufficient to prevent deformation of the battery can 20 during the process of connecting the cell terminal 40 and the first current collector plate 50 using the terminal fastening member 60 (described below). However, this does not limit the material of the battery can 20, and any conductive metal material can be used. The battery can 20 accommodates the electrode assembly 10 through the opening at the bottom, along with the electrolyte.

[0061] The battery can 20 is electrically connected to the electrode assembly 10. The battery can 20 may be electrically coupled to, for example, the second electrode tab 12 of the electrode assembly 10. In this case, the battery can 20 has the same second polarity as the second electrode tab 12.

[0062] The battery can 20 may have a bead portion 21 formed near its lower end. The bead portion 21 is formed by press-fitting the periphery of the outer periphery of the battery can 20 at the open end of the battery can 20. As a result, the battery can 20 has a recessed shape of a predetermined depth in the area where the bead portion 21 is formed. The bead portion 21 prevents the electrode assembly 10, which has a size approximately corresponding to the inner diameter of the battery can 20, from slipping out through the opening formed at the lower end of the battery can 20, and may function as a support portion on which the cap plate 30 is seated. Referring to FIG. 8 , an upper surface of the bead portion 21 on the inner surface of the battery can 20 may function as a support surface on which the electrode assembly 10 is seated. In addition, a lower surface of the bead portion 21 on the inner surface of the battery can 20 may function as a support surface on which the cap plate 30 is seated. Meanwhile, the lower surface of the bead portion 21 on the inner surface of the battery can 20 can also function as a support surface on which a can coupling portion 83 of a second current collector plate 80, which will be described later, is seated.

[0063] The battery can 20 may include a crimping portion 22 formed below the bead portion 21. The crimping portion 22 extends downward from the bead portion 21. The crimping portion 22 extends and bends to surround the outer circumferential surface of the cap plate 30 disposed below the bead portion 21 and a portion of the lower surface of the cap plate 30. The crimping portion 22 may fix a seal gasket G2 in addition to the cap plate 30.

[0064] 3 and 8, the cap plate 30 may be made of, for example, a metal material to ensure rigidity. The cap plate 30 seals an opening formed at the bottom of the battery can 20. The bottom surface of the cap plate 30 forms the bottom surface of the cylindrical battery cell 1. In the cylindrical battery cell 1 of the present invention, the cap plate 30 may be made of a conductive metal material but may not have polarity. "Not having polarity" means that the cap plate 30 is not electrically connected to the electrode assembly 10. When the cap plate 30 is not electrically connected to the electrode assembly 10, the cap plate 30 does not function as a positive or negative terminal. That is, in the present invention, the cap plate 30 does not need to be electrically connected to the electrode assembly 10 and the battery can 20, and its material does not necessarily need to be a conductive metal.

[0065] When the battery can 20 of the present invention includes a bead portion 21, the cap plate 30 may be supported by a lower surface of the bead portion 21 formed on the battery can 20. When the battery can 20 of the present invention includes a crimping portion 22, the cap plate 30 may be fixed by the crimping portion 22. That is, the upper surface of the cap plate 30 may be supported by the bead portion 21, and the outer circumferential surface and the lower surface may also be supported by the bead portion 21. A seal gasket G2 may be interposed between the cap plate 30 and the crimping portion 22 of the battery can 20 to ensure airtightness of the battery can 20. Meanwhile, as described above, the battery can 20 of the present invention may not include the bead portion 21 and / or the crimping portion 22. In this case, the seal gasket G2 may be interposed between the cap plate 30 and a fixing structure provided on the open side of the battery can 20 to ensure airtightness of the battery can 20.

[0066] 8 and 9, the cap plate 30 may further include a vent portion 31 formed to prevent the internal pressure of the battery can 20 from increasing beyond a predetermined value due to gas generated inside the battery can 20. The vent portion 31 corresponds to a region of the cap plate 30 that is thinner than the surrounding region. The vent portion 31 is structurally weaker than the surrounding region. Therefore, when an abnormality occurs in the cylindrical battery cell 1 and the internal pressure of the battery can 20 increases above a certain level, the vent portion 31 ruptures, thereby discharging the gas generated inside the battery can 20. The vent portion 31 may be formed, for example, by notching one or both sides of the cap plate 30 to partially reduce the thickness of the battery can 20.

[0067] As described below, a cylindrical battery cell 1 according to an embodiment of the present invention has a structure in which both a positive electrode terminal and a negative electrode terminal are present at the upper portion, resulting in a more complex structure of the upper portion than the lower portion. Therefore, to facilitate the release of gas generated inside the battery can 20, a vent portion 31 may be formed in a cap plate 30 that seals the open portion of the battery can 20 at the lower end of the cylindrical battery cell 1. As shown in FIG. 7 , the lower end of the cap plate 30 is preferably positioned higher than the lower end of the battery can 20. In this case, even if the lower end of the battery can 20 touches the ground or the bottom of a housing for configuring a module or pack, the cap plate 30 does not touch the ground or the bottom of the housing for configuring a module or pack. This prevents the pressure required for the vent portion 31 to break from changing from the designed value due to the weight of the cylindrical battery cell 1, thereby ensuring smooth rupture of the vent portion 31.

[0068] Meanwhile, the vent portion 31 may have a shape that extends continuously or discontinuously to surround the central region of the cap plate 30, as shown in FIGS. 8 and 9. In this case, from the viewpoint of the ease of rupture of the vent portion 31 due to an increase in internal pressure, the greater the distance from the center of the cap plate 30 to the vent portion 31, the greater the force acting on the vent portion 31, making it easier to rupture, when the same internal pressure is applied. Also, from the viewpoint of smooth discharge of vent gas, the greater the distance from the center of the cap plate 30 to the vent portion 31, the greater the area opened by venting, which is advantageous. From this viewpoint, it may be advantageous for the vent portion 31 to be formed along the outer periphery of a central region that protrudes downward (in the downward direction as viewed in FIG. 8) and has a generally flat shape within the entire region of the cap plate 30.

[0069] 8 and 9 of the present invention show the case where the vent portion 31 is formed continuously in a substantially circular shape on the cap plate 30, but the present invention is not limited thereto. The vent portion 31 may be formed in a substantially elliptical shape that includes the center point of the cap plate 30, or in other geometric shapes. In addition, the vent portion 31 may be formed discontinuously rather than continuously.

[0070] 1 to 4, the cell terminal 40 is electrically connected to the first electrode tab 11. The electrical connection between the first electrode tab 11 and the cell terminal 40 is made via a first current collector plate 50. The cell terminal 40 may be exposed to the outside of the battery can 20 through a closure of the battery can 20.

[0071] The cell terminal 40 is made of a conductive metal material. The cell terminal 40 may include aluminum (Al). Preferably, the cell terminal 40 is made of aluminum. When the cell terminal 40 is made of aluminum, riveting and / or press-fitting using a terminal fastening member 60 for fixing the cell terminal 40 to the inner surface of the closure of the battery can 20 can be easily performed, as described below. When the cell terminal 40 is made of aluminum, 10-series aluminum can be used to maximize ease of processing and minimize electrical resistance.

[0072] The cell terminal 40 has a first polarity similar to the first electrode tab 11 of the electrode assembly 10. Therefore, the cell terminal 40 can function as a first electrode terminal in the cylindrical battery cell 1 of the present invention. When the cell terminal 40 has the first polarity, the cell terminal 40 is electrically insulated from the battery can 20, which has a second polarity. Electrical insulation between the cell terminal 40 and the battery can 20 can be achieved in various ways. For example, insulation can be achieved by interposing an insulating gasket G1 between the cell terminal 40 and the battery can 20. Alternatively, insulation can be achieved by forming an insulating coating layer on a portion of the cell terminal 40. Alternatively, a method can be used in which the cell terminal 40 is structurally and firmly fixed so that the cell terminal 40 and the battery can 20 cannot come into contact with each other. Alternatively, a combination of the above methods can be used.

[0073] 4 , the cell terminal 40 includes a terminal exposing portion 41 and a terminal inserting portion 42. The terminal inserting portion 42 may include an electrical connection portion 42a and a flange portion 42b. The terminal exposing portion 41 is exposed to the outside of the battery can 20. The terminal exposing portion 41 may be located approximately at the center of the closed portion of the battery can 20. The maximum width of the terminal exposing portion 41 may be greater than the maximum width of the hole formed in the battery can 20 for inserting the cell terminal 40. The terminal inserting portion 42 passes through approximately the center of the closed portion of the battery can 20, and the electrical connection portion 42a of the terminal inserting portion 42 may be electrically connected to the first electrode tab 11. The bottom surface of the cell terminal 40, i.e., the bottom surface of the electrical connection portion 42a, may have a substantially flat shape with at least a portion of the bottom surface being substantially parallel to the closed portion of the battery can 20. In this way, when part or all of the bottom surface of the cell terminal 40 has a substantially flat shape, it is possible to maximize the contact area between the cell terminal 40 and the first current collecting plate 50 used for the electrical connection between the cell terminal 40 and the first electrode tab 11, thereby minimizing contact resistance. In this way, maximizing the contact area at the electrical connection portion between the electrode assembly 10 and the cell terminal 40 and thereby minimizing contact resistance ensures a smooth current flow at the connection portion between the cell terminal 40 and the first current collecting plate 50 when a large amount of current flows due to fast charging, thereby achieving effects such as shortening charging time and reducing heat generation.

[0074] The flange portion 42b of the terminal insertion portion 42 may be formed around the electrical connection portion 42a and may be rivet-connected to the inner surface of the closure of the battery can 20. That is, the flange portion 42b of the terminal insertion portion 42 may have a curved shape toward the inner surface of the closure of the battery can 20. Therefore, the maximum width of the terminal insertion portion 42 after the riveting process for fixing the cell terminal 40 is performed may be larger than the maximum width of the hole formed in the battery can 20 so that the terminal insertion portion 42 can pass through.

[0075] The electrical connection portion 42a of the terminal insertion portion 42 may be coupled to a first current collecting plate 50, which will be described later. The electrical connection portion 42a of the terminal insertion portion 42 may be, for example, substantially cylindrical. Of course, the shape of the electrical connection portion 42a of the terminal insertion portion 42 is not limited thereto. The electrical connection portion 42a of the terminal insertion portion 42 may have various shapes, such as a cylindrical shape having an elliptical cross section, a rectangular prism, a hexagonal prism, or an octagonal prism. The bottom surface of the electrical connection portion 42a of the terminal insertion portion 42 may be at least partially formed to be substantially flat.

[0076] The insulating gasket G1 is interposed between the battery can 20 and the cell terminal 40 to prevent the battery can 20 and the cell terminal 40, which have opposite polarities, from coming into contact with each other. This allows the outer surface 20a of the closure of the battery can 20, which has a substantially flat shape, to function as the second electrode terminal of the cylindrical battery cell 1.

[0077] The insulating gasket G1 includes a gasket exposed portion G1A and a gasket insert portion G1B. The gasket exposed portion G1A is interposed between the terminal exposed portion 41 of the cell terminal 40 and the battery can 20. The gasket exposed portion G1A may extend longer than the terminal exposed portion 41 in a direction substantially parallel to the closure of the battery can 20 to maximize insulation. As a result, when the cylindrical battery cell 1 is viewed from above, a portion of the gasket exposed portion G1A may be exposed outside the terminal exposed portion 41. The gasket insert portion G1B is interposed between the terminal insert portion 42 of the cell terminal 40 and the battery can 20. The gasket insert portion G1B may deform during riveting using the flange portion 42b of the terminal insert portion 42, and may adhere to the inner surface of the closure of the battery can 20. The insulating gasket G1 may be made of, for example, a resin material having insulating and elastic properties.

[0078] When the insulating gasket G1 is made of a resin material, the insulating gasket G1 can be bonded to the battery can 20 and the cell terminal 40 by heat fusion. In this case, it is possible to improve the airtightness at the bonding interface between the insulating gasket G1 and the cell terminal 40 and at the bonding interface between the insulating gasket G1 and the battery can 20. Meanwhile, although not shown, the gasket exposed portion G1A of the insulating gasket G1 can have a shape that extends to cover the outer peripheral surface of the terminal exposed portion 41, or a shape that extends to cover not only the outer peripheral surface but also a portion of the upper surface of the terminal exposed portion 41. When the gasket exposed portion G1A of the insulating gasket G1 has a shape that extends to cover the outer peripheral surface and a portion of the upper surface of the terminal exposed portion 41, the cell terminal 40 can be formed integrally with the insulating gasket G1 by, for example, insert injection.

[0079] Of the entire area of ​​the upper surface of the battery can 20 viewed from above the cylindrical battery cell 1, the entire remaining area excluding the area occupied by the cell terminal 40 and the insulating gasket G1, i.e., the area occupied by the outer surface 20a of the closing part of the battery can 20, corresponds to the second electrode terminal having the opposite polarity to the cell terminal (first electrode terminal) 40.

[0080] 3 and 4, the first current collector 50 is coupled to the upper portion of the electrode assembly 10. The first current collector 50 is also coupled to the cell terminal 40. More specifically, the first current collector 50 has a first surface and a second surface opposite to the first surface, the first surface being coupled to the first electrode tab 11, and the second surface being coupled to the cell terminal 40. Thus, the first current collector 50 electrically connects the first electrode tab 11 of the electrode assembly 10 to the cell terminal 40. The first current collector 50 is made of a conductive metal material and is coupled to the first electrode tab 11. When the first electrode tab 11 is a positive electrode tab, the first current collector 50 may include, for example, aluminum. Preferably, the first current collector 50 may be made of an aluminum material.

[0081] A flat portion is formed on at least a portion of the bottom surface of the cell terminal 40, i.e., the bottom surface of the electrical connection portion 42a of the terminal insertion portion 42, which is approximately parallel to the inner surface of the closing portion of the battery can 20, and the first current collector plate 50 is coupled to this flat portion.

[0082] The first current collecting plate 50 is connected to an end of the first electrode tab 11. The first electrode tab 11 and the first current collecting plate 50 can be connected by, for example, laser welding. The laser welding can be performed by partially melting the base material of the first current collecting plate 50, or by interposing solder between the first current collecting plate 50 and the first electrode tab 11. In this case, it is preferable that the solder has a lower melting point than the first current collecting plate 50 and the first electrode tab 11.

[0083] The first current collector plate 50 may be coupled to a coupling surface formed by bending an end of the first electrode tab 11 in a direction parallel to the first current collector plate 50. The first electrode tab 11 may be bent along the radial direction of the electrode assembly 10. The bending direction of the first electrode tab 11 may be, for example, toward the winding center, i.e., the core, of the electrode assembly 10. When the first electrode tab 11 has such a bent shape, the space occupied by the first electrode tab 11 is reduced, thereby improving energy density. Furthermore, when the first electrode tab 11 has such a bent shape, the coupling area between the first electrode tab 11 and the first current collector plate 50 is increased, thereby improving coupling strength and reducing resistance. On the other hand, when the end of the first electrode tab 11 has a bent shape and the first current collector 50 is bonded to the bonding surface formed by the bending of the first electrode tab 11, it is advantageous to bond the first current collector 50 to the first electrode tab 11 within an area where the number of layers is uniform, as described above.

[0084] Next, an exemplary embodiment of the first current collecting plate 50 of the present invention will be described with reference to Fig. 7 as well as Figs. 3 and 4. Referring to Fig. 7 as well as Figs. 3 and 4, the first current collecting plate 50 applied to the present invention includes a first tab coupling portion 52 coupled to the first electrode tab 11 and a terminal coupling portion 53 coupled to the cell terminal 40. The first current collecting plate 50 may further include a frame portion 51.

[0085] The frame 51 is disposed on the upper portion of the electrode assembly 10. The frame 51 may have a substantially rim-like shape with an empty space S formed therein. Although the drawings of the present invention show only the case where the frame 51 has a substantially circular rim-like shape, the present invention is not limited thereto. Unlike the drawings, the frame 51 may have a substantially square rim-like shape, a hexagonal rim-like shape, an octagonal rim-like shape, or other rim-like shapes.

[0086] For example, the terminal coupling portion 53 may have a diameter substantially equal to or larger than the diameter of the flat portion formed on the bottom surface of the cell terminal 40 in order to secure an area for coupling with the flat portion formed on the bottom surface of the cell terminal 40. However, the area of ​​the terminal coupling portion 53 is not limited thereto.

[0087] The first tab coupling portion 52 extends inward from the frame portion 51 to couple with the first electrode tab 11. The terminal coupling portion 53 is located inside the frame portion 51 and spaced apart from the first tab coupling portion 52. As described below, the terminal coupling portion 53 may be coupled to the cell terminal 40 by a mechanical fastening method. The terminal coupling portion 53 may be located, for example, approximately at the center of the inner space surrounded by the frame portion 51. The terminal coupling portion 53 may be provided at a position corresponding to a winding center hole C formed in a core portion of the electrode assembly 10. The terminal coupling portion 53 may be configured to cover the winding center hole C of the electrode assembly 10 so that the winding center hole C of the electrode assembly 10 is not exposed to the outside of the terminal coupling portion 53. When the winding center hole C of the electrode assembly 10 is covered in this way, it is possible to prevent a separator located inside the hole from being damaged due to the flow rate of the electrolyte passing through the hole, thereby preventing the electrode from being exposed. For this purpose, the terminal coupling portion 53 may have a diameter or width larger than the central winding hole C of the electrode assembly 10 .

[0088] The first tab coupling portion 52 and the terminal coupling portion 53 may not be directly connected but may be spaced apart from each other and may be indirectly connected via the frame portion 51. As such, the first current collector plate 50 has a structure in which the first tab coupling portion 52 and the terminal coupling portion 53 are not directly connected to each other but are only indirectly connected via the frame portion 51, thereby dispersing impact. That is, when impact and / or vibration occurs in the cylindrical battery cell 1 of the present invention, the impact applied to the coupling portion between the first tab coupling portion 52 and the first electrode tab 11 and the coupling portion between the terminal coupling portion 53 and the cell terminal 40 can be dispersed. Although the drawings of the present invention show only four first tab coupling portions 52, the present invention is not limited thereto. The number of first tab coupling portions 52 may be determined in various ways taking into consideration factors such as the difficulty of manufacturing due to the complexity of the shape, electrical resistance, and the internal space of the frame portion 51 in consideration of electrolyte impregnation.

[0089] The first current collecting plate 50 may further include a bridge portion 54 extending inward from the frame portion 51 and connected to the terminal coupling portion 53. The bridge portion 54 may include a current blocking portion N formed to partially reduce the cross-sectional area of ​​the bridge portion 54. The cross-sectional area of ​​the current blocking portion N may be adjusted by, for example, partially reducing the width and / or thickness of the bridge portion 54. When the current blocking portion N is provided, electrical resistance in the area where the current blocking portion N is formed increases, thereby enabling rapid current interruption when an overcurrent occurs. The current blocking portion N may have the form of a notch, groove, hole, or the like formed on at least one surface of the bridge portion 54.

[0090] Meanwhile, the current interrupting portion N is preferably provided in a region corresponding to the uniform layer count region of the electrode assembly 10 to prevent problems such as an internal short circuit caused by foreign matter generated during breakage entering the electrode assembly 10. This is because the number of overlapping layers of the segments 11a (see FIG. 2) of the first electrode tab 11 is maximized in this region, allowing the overlapping segments to function as a mask. For example, the current interrupting portion N may be provided in a region corresponding to approximately the center of the electrode assembly 10 in the radial direction.

[0091] The first tab coupling portions 52 may be provided in plurality. The first tab coupling portions 52 may be arranged at substantially equal intervals from one another along the extension direction of the frame portion 51. The extension lengths of the first tab coupling portions 52 may be substantially equal to one another. The first tab coupling portions 52 may be coupled to the first electrode tabs 11 by, for example, welding.

[0092] The terminal coupling portion 53 may be arranged to be surrounded by the plurality of first tab coupling portions 52. The terminal coupling portion 53 may be coupled to the cell terminal 40 by a terminal fastening member 60. The bridge portion 54 may be located between a pair of adjacent first tab coupling portions 52. In this case, the distance from the bridge portion 54 to one of the pair of first tab coupling portions 52 along the extension direction of the frame portion 51 may be substantially the same as the distance from the bridge portion 54 to the other of the pair of first tab coupling portions 52 along the extension direction of the frame portion 51. The cross-sectional areas of the plurality of first tab coupling portions 52 may be substantially the same. The widths and thicknesses of the plurality of first tab coupling portions 52 may be substantially the same.

[0093] Although not shown, a plurality of bridge portions 54 may be provided. In this case, each of the plurality of bridge portions 54 may be disposed between a pair of adjacent first tab coupling portions 52. The plurality of bridge portions 54 may be disposed at substantially equal intervals from one another along the extension direction of the frame portion 51. The distance from each of the plurality of bridge portions 54 to one of the pair of adjacent first tab coupling portions 52 along the extension direction of the frame portion 51 may be substantially the same as the distance to the other first tab coupling portion 52.

[0094] As described above, when multiple first tab connection portions 52 and / or bridge portions 54 are provided, if the distance between the first tab connection portions 52, and / or the distance between the bridge portions 54, and / or the distance between the first tab connection portions 52 and the bridge portions 54 are formed to be constant, a smooth flow of current can be formed from the first tab connection portions 52 to the bridge portions 54 or from the bridge portions 54 to the first tab connection portions 52.

[0095] 4 and 5, the terminal fastening member 60 couples the cell terminal 40 and the first current collector plate 50. That is, in the present invention, the cell terminal 40 and the first current collector plate 50 can be coupled by a mechanical fastening method using a separate fastening member rather than welding. If welding is used to couple the cell terminal 40 and the first current collector plate 50, welding spatter (in the case of laser welding) or splash may occur, which may cause metal foreign matter to enter the electrode assembly 10. When electrolyte is poured, the metal foreign matter may move along with the electrolyte and cause an internal short circuit. Therefore, in the present invention, a mechanical fastening method may be used to couple the cell terminal 40 and the first current collector plate 50, thereby solving this problem.

[0096] In particular, in the cylindrical battery cell 1 according to the present invention, because the cell terminal 40 is located on the closed side of the battery can 20, the process for connecting the cell terminal 40 and the first current collecting plate 50 must be performed in the direction of the arrow in FIG. 5 through the winding center hole C of the electrode assembly 10. If welding is used to connect the cell terminal 40 and the first current collecting plate 50, metal foreign matter generated by welding spatter or splash inside the winding center hole C may damage the separator forming the inner wall surface of the winding center hole C. Therefore, considering the structure of the cylindrical battery cell 1 according to the present invention, it is significant to use a mechanical fastening method to connect the cell terminal 40 and the first current collecting plate 50. The terminal fastening member 60 may connect the cell terminal 40 and the first current collecting plate 50 using, for example, a self-piercing rivet (SPR) method. The terminal fastening member 60 may be press-fitted into the inside of the first current collector plate 50 and the cell terminal 40 to fasten the cell terminal 40 and the first current collector plate 50. The terminal fastening member 60 may include a base portion 61 and a fastening portion 62. The base portion 61 may be disposed approximately parallel to the first current collector plate 50. The fastening portion 62 may extend from the base portion 61 toward the first current collector plate 50 and be press-fitted from the surface of the first current collector plate 50 into the inside of the first current collector plate 50 and the cell terminal 40. More specifically, the fastening portion 62 may be press-fitted into a lower surface of a terminal coupling portion 53 (a surface facing the inside of the winding center hole C among both surfaces of the terminal coupling portion 53) provided on the first current collector plate 50 and a bottom surface of the cell terminal 40.

[0097] The terminal coupling portion 53 of the first current collector plate 50 may be recessed inward through the bottom surface of the cell terminal 40 during the press-fitting process, thereby allowing the first current collector plate 50 to closely contact the cell terminal 40 while maximizing the contact area with the cell terminal 40. The fastening portion 62 of the terminal fastening member 60 may penetrate the terminal coupling portion 53 at a position where it is press-fitted to a predetermined depth from the bottom surface of the cell terminal 40. Alternatively, the fastening portion 62 of the terminal fastening member 60 may not penetrate the first current collector plate 50 until it reaches the maximum press-fit depth.

[0098] The fastening portion 62 is configured to form a space therein and may have a sidewall shape that continuously or discontinuously surrounds the empty space. At least a portion of the first current collector plate 50 can be inserted into the cell terminal 40 from the bottom surface thereof by press-fitting the fastening portion 62 on both the outside and inside of the fastening portion 62. After the terminal fastening member 60 is completely press-fitted, the first current collector plate 50 can contact both the base portion 61 and the fastening portion 62 on the outside of the fastening portion 62, and can also contact both the base portion 61 and the fastening portion 62 in the space formed inside the fastening portion 62. As described above, the terminal fastening member 60 is inserted through the winding center hole C of the electrode assembly 10 to couple the first electrode current collector plate 50 and the cell terminal 40. In addition, it is preferable to first insert a blank holder B into the winding center hole C to guide the insertion of the terminal fastening member 60 and protect the separator that forms the inner wall surface of the winding center hole C. Therefore, the maximum diameter or width of the terminal fastening member 60 must be smaller than the diameter of the winding center hole C of the electrode assembly 10 .

[0099] The terminal fastening member 60 may be made of boron steel (boron steel) material to which a trace amount of boron in the range of approximately 0.001 to 0.008 wt% is added. Such boron steel has an advantage of being very hard and therefore excellent in abrasion resistance. The inventors have compared the results of a case where the cell terminal 40 and the first current collector plate 50 made of aluminum are fastened by a self-piercing riveting method using the terminal fastening member 60 made of boron steel (Example) and a case where they are fastened by laser welding. Combined In this study, it was confirmed that the resistance measured between the bottom surface of the terminal fastening member 60 and the upper surface of the cell terminal 40 (approximately 0.12 to 0.22 mΩ) was lower or at a similar level compared to the resistance measured between the first tab coupling portion 52 of the first current collector plate 50 and the upper surface of the cell terminal 40 (approximately 0.2 mΩ).

[0109] When the cylindrical battery cell 1 according to an embodiment of the present invention includes the insulator 70, the terminal insertion portion 42 of the cell terminal 40 is coupled to the terminal coupling portion 53 of the first current collector plate 50 through a hole formed in the insulator 70. The hole formed in the insulator 70 may be formed at a position corresponding to the winding center hole C of the electrode assembly 10. In addition, the hole formed in the insulator 70 may be formed at a position corresponding to the terminal coupling portion 53 of the first current collector plate 50.

[0110] The insulator 70 fills the space between the inner surface of the closed portion of the battery can 20 and the first current collector plate 50 along the height direction, and may have a thickness corresponding to the distance between the inner surface of the closed portion of the battery can 20 and the first current collector plate 50 so as to prevent a space from being generated through which the electrode assembly 10 can move up and down. In another aspect, the upper surface of the insulator 70 may contact the inner surface of the closed portion of the battery can 20, and the lower surface of the insulator 70 may contact the upper surface of the first current collector plate 50.

[0111] 8, the second current collecting plate 80 is disposed at the bottom of the electrode assembly 10. The second current collecting plate 80 may be configured to electrically connect the second electrode tab 12 of the electrode assembly 10 and the battery can 20. The second current collecting plate 80 is made of a conductive metal material and is connected to the second electrode tab 12. The second current collecting plate 80 is electrically connected to the battery can 20. The second current collecting plate 80 may be interposed and fixed between an inner surface of the battery can 20 and a seal gasket G2. The second current collecting plate 80 may be interposed, for example, between a lower surface of a bead portion 21 provided on the battery can 20 and the seal gasket G2.

[0112] The second current collecting plate 80 is connected to an end of the second electrode tab 12. The second electrode tab 12 and the second current collecting plate 80 are connected by, for example, laser welding. The laser welding may be performed by partially melting the base material of the second current collecting plate 80, or may be performed with solder interposed between the second current collecting plate 80 and the second electrode tab 12. In this case, it is preferable that the solder has a lower melting point than the second current collecting plate 80 and the second electrode tab 12.

[0113] The second current collector plate 80 may be bonded to a bonding surface formed by bending an end of the second electrode tab 12 in a direction parallel to the second current collector plate 80. The bending of the second electrode tab 12 may be performed along the radial direction of the electrode assembly 10. The bending direction of the second electrode tab 12 may be, for example, toward the core of the electrode assembly 10. When the second electrode tab 12 has such a bent shape, the space occupied by the second electrode tab 12 is reduced, thereby improving energy density. Furthermore, when the second electrode tab 12 has such a bent shape, the bonding area between the second electrode tab 12 and the second current collector plate 80 is increased, thereby improving bonding strength and reducing resistance. Meanwhile, when the end of the second electrode tab 12 has a bent shape and the second current collector plate 80 is bonded to a bonding surface formed by bending the second electrode tab 12, it is advantageous to bond the second current collector plate 80 to the second electrode tab 12 within a region where the number of layers is uniform, as described above.

[0114] The second current collector plate 80 may have a current collector plate hole 80a formed at a position corresponding to a winding center hole C formed in the core portion of the electrode assembly 10. The winding center hole C of the electrode assembly 10 and the current collector plate hole 80a, which are connected to each other, may function as a passage for inserting a terminal fastening member 60 for coupling the cell terminal 40 to the terminal coupling portion 53 of the first current collector plate 50, and for inserting a tool for press-fitting the terminal fastening member 60 into the first current collector plate 50 and the cell terminal 40. In consideration of this function, the current collector plate hole 80a may have a diameter substantially the same as or larger than that of the hole formed in the winding center of the electrode assembly 10. The current collector plate hole 80a may also be used as a passage for injecting an electrolyte.

[0115] The can coupling portion 83 may be electrically coupled to the battery can 20 at multiple points. In this case, the coupling area between the second current collecting plate 80 and the battery can 20 may be maximized and current paths may be multiplied, thereby minimizing electrical resistance at the coupling portion between the second current collecting plate 80 and the battery can 20. The can coupling portion 83 may be coupled to the lower surface of the bead portion 21, for example.

[0116] More specifically, the can coupling part 83 may be electrically coupled to a flat part formed on the lower surface of the bead part 21 formed on the battery can 20, and may be interposed between the lower surface of the bead part 21 and the seal gasket G2. In this case, for stable contact and coupling, the can coupling part 83 may have a shape that extends a predetermined length along the circumferential direction of the battery can 20 on the bead part 21.

[0117] Meanwhile, it is preferable that the length obtained by multiplying the maximum distance from the center of the second current collector plate 80 to the end of the second tab coupling portion 82 along the radial direction of the electrode assembly 10 by 2 be substantially equal to or smaller than the inner diameter of the battery can 20 in the region where the bead portion 21 is formed, i.e., the minimum inner diameter of the battery can 20. This is to prevent interference between the second current collector plates 80 due to the bead portion 21 during a sizing process in which the battery can 20 is compressed in the height direction (direction parallel to the Z axis), thereby preventing the electrode assembly 10 from being pressed by the second current collector plate 80.

[0118] Meanwhile, in the cylindrical battery cell 1 according to an embodiment of the present invention, as described above, the cap plate 30 does not necessarily have polarity. When the cap plate 30 does not have polarity, the second current collector plate 80 is connected to the sidewall of the battery can 20, and therefore the outer surface 20a of the closure of the battery can 20 has the opposite polarity to the cell terminal 40. Therefore, when connecting multiple cylindrical battery cells 1 in series and / or parallel, wiring work such as bus bar connection can be performed at the top of the cylindrical battery cell 1 using the outer surface 20a of the closure of the battery can 20 and the cell terminal 40. This increases the number of cylindrical battery cells 1 that can be installed in the same space, improves energy density, and facilitates electrical wiring work. That is, in the cylindrical battery cell 1 according to the present invention, the cell terminal 40 exposed to the outside of the battery can 20 can function as a first electrode terminal, and the region of the outer surface 20a of the closure of the battery can 20 that is approximately parallel to the top surface of the first electrode terminal can function as a second electrode terminal. Therefore, when electrically connecting multiple cylindrical battery cells 1, a first bus bar can be coupled to the upper surface of the cell terminal 40 exposed to the outside of the battery can 20, and a second bus bar can be coupled to the area of ​​the exposed surface of the outer surface 20a of the closing part of the battery can 20 that is approximately parallel to the upper surface of the first electrode terminal.

[0119] 10, a plurality of cylindrical battery cells 1 may be connected in series and parallel at the top of the cylindrical battery cells 1 using bus bars 150. The number of cylindrical battery cells 1 may be increased or decreased depending on the capacity of the battery pack.

[0120] In each cylindrical battery cell 1, the cell terminal 40 may have a positive polarity and the outer surface 20a of the closure of the battery can 20 may have a negative polarity. Of course, the reverse is also possible.

[0121] Preferably, the plurality of cylindrical battery cells 1 may be arranged in a plurality of columns and rows. The columns are in the vertical direction with reference to FIG. 10, and the rows are in the horizontal direction with reference to FIG. 10. Furthermore, to maximize space efficiency, the cylindrical battery cells 1 may be arranged in a closest packing structure. The closest packing structure is formed by connecting the centers of the exposed terminal portions 41 of the cell terminals 40 exposed to the outside of the battery can 20 to form an equilateral triangle. Preferably, the bus bar 150 may be arranged on top of the plurality of cylindrical battery cells 1, more preferably between adjacent columns. Alternatively, the bus bar 150 may be arranged between adjacent rows.

[0122] For example, the bus bars 150 may connect the cylindrical battery cells 1 arranged in the same row in parallel to each other, and may connect the cylindrical battery cells 1 arranged in two adjacent rows in series to each other.

[0123] The bus bar 150 may include a body portion 151, a plurality of first bus bar terminals 152, and a plurality of second bus bar terminals 153 for series and parallel connection.

[0124] The body portion 151 may extend between the cell terminals 40 of adjacent cylindrical battery cells 1, preferably between rows of cylindrical battery cells 1. Alternatively, the body portion 151 may extend along the rows of cylindrical battery cells 1 and be bent regularly, such as in a zigzag shape.

[0125] The plurality of first bus bar terminals 152 may protrude from one side of the body part 151 toward the cell terminals 40 of the respective cylindrical battery cells 1 and be electrically coupled to the cell terminals 40. The electrical coupling between the first bus bar terminals 152 and the cell terminals 40 may be performed by laser welding, ultrasonic welding, etc. In addition, the plurality of second bus bar terminals 153 may be electrically coupled to the outer surface 20 a of the respective cylindrical battery cells 1 from the other side of the body part 151. The electrical coupling between the second bus bar terminals 153 and the outer surface 20 a may be performed by laser welding, ultrasonic welding, etc.

[0126] Preferably, the body portion 151, the plurality of first bus bar terminals 152, and the plurality of second bus bar terminals 153 may be formed from a single conductive metal plate. The metal plate may be, for example, an aluminum plate or a copper plate, but the present invention is not limited thereto. In a modified example, the body portion 151, the plurality of first bus bar terminals 152, and the plurality of second bus bar terminals 153 may be manufactured as separate pieces and then joined together by welding or the like.

[0127] In the cylindrical battery cell 1 according to the present invention, the cell terminal 40 having a positive polarity and the outer surface 20a of the closure of the battery can 20 having a negative polarity are positioned in the same direction, so that electrical connection of the cylindrical battery cell 1 can be easily achieved using the bus bar 150.

[0128] In addition, since the cell terminal 40 of the cylindrical battery cell 1 and the outer surface 20a of the closing part of the battery can 20 have a large area, a sufficient bonding area for the bus bar 150 can be secured, and the resistance of the battery pack including the cylindrical battery cell 1 can be sufficiently reduced.

[0129] Preferably, the cylindrical battery cell may be, for example, a cylindrical battery cell having a form factor ratio (defined as the diameter of a cylindrical battery cell divided by its height, i.e., the ratio of the diameter (Φ) to the height (H)) of greater than approximately 0.4.

[0130] Here, the form factor refers to values ​​indicating the diameter and height of a cylindrical battery cell. Cylindrical battery cells according to an embodiment of the present invention may be, for example, 46110 cells, 48750 cells, 48110 cells, 48800 cells, and 46800 cells. In the numerical value indicating the form factor, the first two digits indicate the diameter of the cell, the next two digits indicate the height of the cell, and the last digit 0 indicates that the cross section of the cell is circular.

[0131] A battery cell according to one embodiment of the present invention may be a cylindrical battery cell having a substantially cylindrical shape with a diameter of approximately 46 mm, a height of approximately 110 mm, and a form factor ratio of approximately 0.418.

[0132] A battery cell according to another embodiment may be a cylindrical battery cell having a substantially cylindrical shape with a diameter of approximately 48 mm, a height of approximately 75 mm, and a form factor ratio of approximately 0.640.

[0133] A battery cell according to another embodiment may be a cylindrical battery cell having a substantially cylindrical shape with a diameter of approximately 48 mm, a height of approximately 110 mm, and a form factor ratio of approximately 0.418.

[0134] A battery cell according to yet another embodiment may be a cylindrical battery cell having a substantially cylindrical shape with a diameter of approximately 48 mm, a height of approximately 80 mm, and a form factor ratio of approximately 0.600.

[0135] A battery cell according to yet another embodiment may be a cylindrical battery cell having a substantially cylindrical shape with a diameter of approximately 46 mm, a height of approximately 80 mm, and a form factor ratio of approximately 0.575.

[0136] Conventionally, battery cells with a form factor ratio of approximately 0.4 or less have been used. For example, 18650 cells, 21700 cells, etc. have been used. 18650 cells have a diameter of approximately 18 mm, a height of approximately 65 mm, and a form factor ratio of approximately 0.277. 21700 cells have a diameter of approximately 21 mm, a height of approximately 70 mm, and a form factor ratio of approximately 0.300.

[0137] As described above, the cylindrical battery cell 1 of the present invention has a structure in which resistance is minimized by increasing the contact area between components, multiplexing current paths, minimizing the length of the current paths, etc. After the product is completed, the AC resistance of the cylindrical battery cell 1 measured with a resistance meter between the positive and negative electrodes, i.e., between the top surface of the cell terminal 40 and the outer surface 20a of the closure of the battery can 20, can be approximately 4 mΩ (mohm) or less.

[0138] 11, a battery pack 3 according to an embodiment of the present invention includes a secondary battery assembly in which a plurality of cylindrical battery cells 1 according to an embodiment of the present invention are electrically connected as described above, and a pack housing 2 that accommodates the secondary battery assembly. For ease of illustration, components such as bus bars for electrical connection, a cooling unit, and power terminals are omitted from FIG. 11 of the present invention. The electrical connection structure of a plurality of battery cells 1 for manufacturing the battery pack 3 has been exemplarily described above with reference to FIG. 10.

[0139] 12, an automobile 5 according to an embodiment of the present invention is, for example, an electric automobile, a hybrid automobile, or a plug-in hybrid automobile, and includes a battery pack 3 according to an embodiment of the present invention. The automobile 5 operates by receiving power from the battery pack 3 according to an embodiment of the present invention.

[0140] The present invention has been described above based on limited embodiments and drawings, but the present invention is not limited to these, and it goes without saying that various changes and modifications can be made by a person having ordinary knowledge in the technical field to which the present invention pertains within the technical spirit of the present invention and the equivalent scope of the claims described below. [Explanation of symbols]

[0141] 5: Automobiles 3: Battery pack 2: Pack housing 1: Cylindrical battery cell 150: Busbar 151: Body 152: First bus bar terminal 153: Second bus bar terminal 10: Electrode assembly C: Winding center hole (core hole) 11: First electrode tab (first uncoated portion) 11a: Split piece 12: Second electrode tab (second plain area) 20: Battery can 20a: Outer surface of the closure (second electrode terminal) 21: Bead section 22: Crimping section 30: Cap plate 31: Vent section 40: Cell terminal (first electrode terminal) 41:Exposed terminal part 42: Terminal insertion part 42a: Electrical connection 42b: Flange part G1: Insulation gasket G1A: Exposed gasket G1B: Gasket insertion part 50: First current collecting plate 51: Frame 52: First tab connection part 53: Terminal connection part 54: Bridge section N: Current interruption part 60: Terminal fastening member 61: Base section 62: Fastening part 70: Insulator 80: Second current collecting plate 80a: Current collector plate hole 82: Second tab connection 83: Can joint H: Liquid injection hole W: Welding pattern G2: Sealing gasket

Claims

1. an electrode assembly including a first electrode tab having a first polarity and a second electrode tab having a second polarity; a battery can having an opening formed at a lower end and a closing portion formed at an upper end, the battery can receiving the electrode assembly through the opening and electrically connected to the second electrode tab; a cell terminal electrically connected to the first electrode tab, exposed to the outside of the battery can through the closing portion of the battery can, and electrically insulated from the battery can; an insulating gasket disposed between the closure of the battery can and the cell terminal; a first current collector plate having a first surface and a second surface opposite to the first surface, the first surface being coupled to the first electrode tab and the second surface being coupled to the cell terminal; a terminal fastening member that mechanically fastens the cell terminal and the first current collector plate; Including, The terminal fastening member is A base portion and a fastening portion extending from the base portion toward the first current collector plate and press-fitted from a surface of the first current collector plate into the inside of the first current collector plate and the cell terminal; a cylindrical battery cell comprising:

2. The terminal fastening member is The cylindrical battery cell according to claim 1 , wherein the first current collector plate and the cell terminal are press-fitted into each other to fasten the cell terminal and the first current collector plate together.

3. The cylindrical battery cell according to claim 1 , wherein the cell terminal and the first current collector plate include aluminum.

4. The terminal fastening member is 4. The cylindrical battery cell according to claim 3, comprising boron steel containing 0.001 wt% to 0.008 wt% boron.

5. 2. The cylindrical battery cell according to claim 1, wherein at least a portion of the first current collector plate is inserted into the cell terminal by press-fitting the fastening portion at an outer side and an inner side of the fastening portion.

6. The maximum diameter or width of the terminal fastening member is: The cylindrical battery cell according to claim 1 , wherein the diameter of the cylindrical battery cell is smaller than the diameter of the central hole of the electrode assembly.

7. The cylindrical battery cell comprises: The cylindrical battery cell according to claim 1 , further comprising a cap plate that seals the opening of the battery can.

8. The cap plate is The cylindrical battery cell according to claim 7 , wherein the cylindrical battery cell is not electrically connected to the electrode assembly, and thus has no polarity.

9. The cylindrical battery cell according to claim 1 , further comprising a second current collector plate electrically connecting the second electrode tab and the battery can.

10. The second current collecting plate is a tab coupling portion coupled to the second electrode tab; a can coupling portion electrically coupled to the battery can; The cylindrical battery cell according to claim 9, comprising:

11. The can joint portion is The cylindrical battery cell according to claim 10 , wherein the battery can is electrically coupled to an inner surface of the side wall.

12. The battery can is a bead portion formed by press-fitting the periphery of the outer circumferential surface of the battery can on the side of the open portion, The can joint portion is The cylindrical battery cell according to claim 11 , wherein the bead portion is electrically coupled to a lower surface of the bead portion.

13. A battery pack comprising a plurality of cylindrical battery cells according to any one of claims 1 to 12.

14. A motor vehicle comprising the battery pack of claim 13.

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