Electrode terminal fixing structure, battery including the same, battery pack, and automobile

Abstract

To provide a cylindrical battery that reduces internal resistance and increases energy density by improving the structure of the electrode terminals of the cylindrical battery to increase space efficiency within a battery housing.SOLUTION: The present invention discloses an electrode terminal fixing structure for a battery including the same, a battery pack, and an automobile. The electrode terminal fixing structure includes a battery housing having a bottom with one side open and the other side formed with a through hole, an electrode terminal attached by passing through the through hole so as not to come into contact with the inner wall of the through hole, and a terminal gasket interposed between the electrode terminal and the through hole, and a hot melt layer interposed at the interface between the electrode terminal and the terminal gasket or the interface between the terminal gasket and the battery housing.SELECTED DRAWING: Figure 6b

Description

[Technical Field]

[0001] The present invention relates to a fixing structure for an electrode terminal, and a battery, a battery pack, and an automobile including the same.

[0002] This application claims priority based on Korean Patent Application No. 10-2022-0090644, filed on July 21, 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 have high applicability to each product group and 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 electrical sources.

[0004] These secondary batteries not only have the primary advantage of dramatically reducing the use of fossil fuels, but are also environmentally friendly as they do not produce any by-products from energy use, and are attracting attention as a new energy source for improving energy efficiency.

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

[0006] Meanwhile, known types of secondary batteries include cylindrical, prismatic, and pouch-type batteries. In the case of cylindrical batteries, a separator, which is an insulator, is interposed between the positive and negative electrodes and wound up to form a jelly-roll-type electrode assembly. This is then inserted into a battery housing together with an electrolyte to form a battery. Strip-shaped electrode tabs are connected to the uncoated portions of the positive and negative electrodes, and the electrode tabs electrically connect the electrode assembly to the electrode terminals exposed to the outside. For reference, the positive terminal is a sealed cap that seals the opening of the battery housing, and the negative terminal is the battery housing.

[0007] However, conventional cylindrical batteries having such a structure have problems such as high resistance, excessive heat generation, and poor current collection efficiency because current is concentrated in the strip-shaped electrode tabs connected to the positive electrode uncoated region and / or the negative electrode uncoated region.

[0008] Resistance and heat generation are not major issues for small cylindrical batteries with form factors such as 1865 (diameter: 16mm, height: 65mm) and 2170 (diameter: 21mm, height: 70mm). However, when the form factor of cylindrical batteries is increased to be used in electric vehicles, a large amount of heat is generated around the electrode tabs during the fast charging process, which can cause the cylindrical battery to catch fire.

[0009] To solve this problem, a cylindrical battery (so-called tab-less cylindrical battery) has been proposed, which has a structure in which positive and negative electrode uncoated areas are located at the top and bottom of a jelly-roll type electrode assembly, respectively, and current collectors are welded to these uncoated areas to improve current collection efficiency.

[0010] Figures 1 to 3 show the manufacturing process of a tabless cylindrical battery. Figure 1 shows the structure of the electrode, Figure 2 shows the electrode winding process, and Figure 3 shows the process of welding a current collector to the folded surface of the uncoated portion. Figure 4 is a cross-sectional view of the tabless cylindrical battery cut in the longitudinal direction (Y axis).

[0011] 1 to 4, the positive electrode 10 and the negative electrode 11 have a structure in which an active material 21 is coated on a sheet-shaped current collector 20, and include a plain portion 22 on one long side along the winding direction X.

[0012] The electrode assembly A is fabricated by sequentially stacking a positive electrode 10 and a negative electrode 11 together with two separators 12, as shown in Figure 2, and then winding the stack in one direction (X-axis direction). At this time, the uncoated portion of the positive electrode 10 and the uncoated portion of the negative electrode 11 are arranged in opposite directions.

[0013] After the winding process, the uncoated portion 10a of the positive electrode 10 and the uncoated portion 11a of the negative electrode 11 are folded toward the core. Thereafter, the current collectors 30 and 31 are welded and joined to the uncoated portions 10a and 11a, respectively.

[0014] No separate electrode tabs are attached to the positive electrode uncoated region 10a and the negative electrode uncoated region 11a, and current collectors 30 and 31 are connected to external electrode terminals, forming a current path with a large cross-sectional area along the winding axis direction of electrode assembly A (see arrow in FIG. 3), which has the advantage of reducing battery resistance, since resistance is inversely proportional to the cross-sectional area of ​​the path through which current flows.

[0015] However, as the form factor of cylindrical batteries increases and the charging current during fast charging increases, the heat generation problem reoccurs even in tableless cylindrical batteries.

[0016] Specifically, as shown in Figure 4, a conventional tabless cylindrical battery 40 includes a battery housing 41 and a sealing body 42. The battery housing 41 is also called a battery can. The sealing body 42 includes a cap 42a, a sealing gasket 42b, and a connecting plate 42c. The sealing gasket 42b encloses the periphery of the cap 42a and is fixed by a crimping portion 43. In addition, the electrode assembly A is fixed inside the battery housing 41 by a beading portion 44 to prevent vertical movement.

[0017] Typically, the positive electrode terminal is the cap 42a of the sealing body 42, and the negative electrode terminal is the battery housing 41. Therefore, the current collector 30 attached to the uncoated portion 10a of the positive electrode 10 is electrically connected to a connecting plate 42c attached to the cap 42a via a strip-shaped lead 45. Also, the current collector 31 attached to the uncoated portion 11a of the negative electrode 11 is electrically connected to the bottom of the battery housing 41. An insulator 46 covers the current collector 30 to prevent contact between the battery housing 41 and the uncoated portion 10a of the positive electrode 10, which have opposite polarities, and causing a short circuit.

[0018] When the current collector 30 is connected to the connecting plate 42c, a strip-shaped lead 45 is used. The lead 45 is either separately attached to the current collector 30 or integrally manufactured with the current collector 30. However, because the lead 45 is a thin strip, its cross-sectional area is small, and a large amount of heat is generated when a fast charging current flows. In addition, the excessive heat generated in the lead 45 is transferred to the electrode assembly A, causing the separator 12 to contract, which can lead to an internal short circuit, a major cause of thermal runaway.

[0019] Furthermore, the leads 45 occupy a considerable amount of installation space within the battery housing 41. Therefore, the cylindrical battery 40 including the leads 45 has low space efficiency and is limited in increasing energy density.

[0020] In addition, the upper end of the crimping portion 43 has a negative polarity but a small area. Although the crimping portion 43 is shown large in the drawings, in reality, the upper end of the crimping portion 43 has a much smaller area than the sealing body 42. Therefore, in order to stably connect the busbar parts, the only way is to connect the positive electrode to the sealing body 42 crimped to the open end of the battery housing 41 and connect the negative electrode to the bottom of the battery housing 41.

[0021] In order to connect conventional table-less cylindrical batteries 40 in series and / or parallel, busbar components must be connected to the cap 42a of the sealed body 42 and the bottom of the battery housing 41, resulting in reduced space efficiency. A battery pack installed in an electric vehicle includes hundreds of cylindrical batteries 40. Therefore, inefficiencies in electrical wiring cause considerable inconvenience during the electric vehicle assembly process and battery pack maintenance. Summary of the Invention [Problem to be solved by the invention]

[0022] The present invention was made in light of the background of the above-mentioned conventional technology, and aims to improve the structure of the electrode terminals of a cylindrical battery to increase the space efficiency within the battery housing, thereby reducing the internal resistance of the cylindrical battery and increasing the energy density.

[0023] Another object of the present invention is to improve the structure of the electrode terminals of a cylindrical battery to increase the cross-sectional area of ​​the current path, thereby alleviating the problem of internal heat generation that occurs during fast charging.

[0024] Another object of the present invention is to improve the structure of electrode terminals of cylindrical batteries and also to improve sealing performance.

[0025] Another object of the present invention is to provide a cylindrical battery with an improved structure in which electrical wiring for series and / or parallel connection of cylindrical batteries can be performed on one side of the cylindrical battery.

[0026] It is yet another object of the present invention to provide a battery pack manufactured using a cylindrical battery having an improved structure, and a vehicle including the same.

[0027] The technical problem to be solved by the present invention is not limited to the above-mentioned object, and other objects and advantages not mentioned will be clearly understood by those skilled in the art from the following description. [Means for solving the problem]

[0028] In order to achieve the above object, according to one aspect of the present invention, there is provided a fixing structure for an electrode terminal, comprising: a battery housing having a bottom with one side open and the other side formed with a through hole; an electrode terminal attached by passing through the through hole so as not to come into contact with the inner wall of the through hole; and a terminal gasket interposed between the electrode terminal and the through hole, wherein a hot melt layer is interposed at the interface between the electrode terminal and the terminal gasket or at the interface between the terminal gasket and the battery housing.

[0029] The electrode terminal may include a main body portion inserted into the through hole, an external flange portion extending from a first side of the main body portion along the outer surface of the bottom of the battery housing, and an internal flange portion extending from a second side of the main body portion so that at least a portion of the internal flange portion faces the inner surface of the bottom of the battery housing.

[0030] The electrode terminal may include a weld portion on the inside of the inner flange portion.

[0031] The weld may include a flat surface.

[0032] The terminal gasket may include an outer gasket interposed between the outer flange portion and a first plane on which the outer surface of the bottom of the battery housing is located, an inner gasket interposed between the inner flange portion and a second plane on which the inner surface of the bottom of the battery housing is located, and an intermediate gasket interposed between the main body portion and the through hole, connecting the outer gasket and the inner gasket.

[0033] The hot melt layer may be interposed at the interface between the inner flange portion and the inner gasket, and at least a portion of the hot melt layer may be exposed.

[0034] The hot melt layer may be interposed between the outer flange portion and the outer gasket, and at least a portion of the hot melt layer may be exposed.

[0035] The hot melt layer may be interposed at the interface between the outer gasket and the first plane, and at least a portion of the hot melt layer may be exposed.

[0036] The hot melt layer may be interposed at the interface between the inner gasket and the second plane, and at least a portion of the hot melt layer may be exposed.

[0037] The hot melt layer may be formed by curing a hot melt film with heat.

[0038] The hot melt layer may be formed by thermally curing a hot melt coating layer.

[0039] The hot melt layer may be made of a silicone-based, epoxy-based, acrylic-based, or urethane-based hot melt material.

[0040] The hot melt layer may have a thickness of several μm to several hundred μm.

[0041] To achieve the above object, according to another aspect of the present invention, a battery includes: an electrode assembly in which a first electrode and a second electrode are wound with a separator interposed therebetween; a battery housing that houses the electrode assembly and is electrically connected to the first electrode; an electrode terminal that is attached through a through hole formed in the bottom of the battery housing and is electrically connected to the second electrode, the electrode terminal including: a body portion inserted into the through hole; an external flange portion that extends from a first side of the body portion along an outer surface of the bottom of the battery housing so as not to come into contact with the inner wall of the through hole; and an internal flange portion that extends from a second side of the body portion so as to face at least a portion of the inner surface of the bottom of the battery housing; a terminal gasket that is interposed between the electrode terminal and the through hole; and a sealing body that seals an open end of the battery housing so as to be insulative from the battery housing, wherein a hot melt layer is interposed at an interface between the electrode terminal and the terminal gasket or at an interface between the terminal gasket and the battery housing.

[0042] The electrode terminal may include a weld portion on the inside of the inner flange portion, and the weld portion may include a flat surface.

[0043] The above object can also be achieved by a battery pack including a plurality of the above-described batteries, and a vehicle including the battery pack. [Effects of the Invention]

[0044] According to one aspect of the present invention, the structure of the electrode terminals of the battery is improved to increase the space efficiency within the battery housing, thereby reducing the internal resistance of the battery and increasing the energy density.

[0045] Furthermore, according to one aspect of the present invention, a hot melt layer can be applied to the structure of the electrode terminal to improve the sealing property of the electrode terminal.

[0046] Furthermore, according to one aspect of the present invention, the problem of internal heat generation occurring during rapid charging can be alleviated by improving the structure of the electrode terminals of the battery to increase the cross-sectional area of ​​the current path.

[0047] Furthermore, according to one aspect of the present invention, electrical wiring for connecting batteries in series and / or in parallel can be performed on one side of the battery.

[0048] According to another aspect of the present invention, a battery pack manufactured using a battery having an improved structure, and a vehicle including the battery pack can be provided.

[0049] The following drawings attached to this specification illustrate preferred embodiments of the present invention and, together with the detailed description of the invention, serve to further understand the technical concept of the present invention. Therefore, the present invention should not be interpreted as being limited to only the matters described in the drawings. [Brief explanation of the drawings]

[0050] [Figure 1]1 is a plan view showing the structure of an electrode used in a conventional tabless cylindrical battery. [Figure 2] 1A and 1B are diagrams illustrating a winding process of an electrode assembly included in a conventional tabless cylindrical battery. [Figure 3] 3 is a view showing a process of welding a current collector to a bent surface of an uncoated portion in the electrode assembly of FIG. 2. FIG. [Figure 4] FIG. 1 is a cross-sectional view of a conventional tablets cylindrical battery cut in the longitudinal direction (Y axis). [Figure 5] 1 is a cross-sectional view showing a fixing structure of an electrode terminal according to an embodiment of the present invention. [Figure 6a] FIG. 6 is an enlarged cross-sectional view of a portion indicated by a dotted circle in FIG. 5. [Figure 6b] FIG. 10 is a partially enlarged cross-sectional view showing a fixing structure for an electrode terminal according to another embodiment of the present invention. [Figure 6c] 3 is a plan view schematically showing a welding pattern formed on a flat portion of an electrode terminal according to an embodiment of the present invention. FIG. [Figure 6d] 1 is a photograph of the surface of a cylindrical battery with exposed electrode terminals after a thermal shock cycle test. [Figure 6e] 10 is a photograph showing the results of measuring the gap between the terminal gasket and the electrode terminal before and after a thermal shock cycle test. [Figure 6f] 1 is a cross-sectional view showing an improved electrode terminal structure for solving the problem of electrolyte leakage confirmed in a thermal shock cycle experiment. [Figure 7a] 1 is a cross-sectional view of a cylindrical battery according to an embodiment of the present invention taken along the longitudinal direction (Y axis). [Figure 7b] 4 is a cross-sectional view of a cylindrical battery according to another embodiment of the present invention taken along the longitudinal direction (Y-axis). FIG. [Figure 8] 1 is a plan view illustrating an example of an electrode structure according to a preferred embodiment of the present invention; [Figure 9] 1 is a cross-sectional view taken along the longitudinal direction (Y-axis) of an electrode assembly in which a division structure of an uncoated portion of an electrode according to an embodiment of the present invention is applied to first and second electrodes. [Figure 10a] 3 is a cross-sectional view of an electrode assembly in which an uncoated portion is folded in accordance with an embodiment of the present invention, taken along the longitudinal direction (Y-axis). [Figure 10b] 1 is a perspective view of an electrode assembly in which a non-coating portion is folded according to an embodiment of the present invention; [Figure 11] 1 is a top view illustrating a state in which a plurality of cylindrical batteries are connected in series and parallel using bus bars according to an embodiment of the present invention. FIG. [Figure 12a] FIG. 12 is an enlarged view of a part of FIG. [Figure 12b] FIG. 10 is a diagram illustrating exemplary parameters used to define the diameter of an electrode terminal and the exposed width of the outer surface of the bottom of a battery housing according to an embodiment of the present invention. [Figure 12c] FIG. 10 is a diagram illustrating exemplary parameters used to define the diameter of an electrode terminal and the exposed width of the outer surface of the bottom of a battery housing according to an embodiment of the present invention. [Figure 13] 1 is a diagram illustrating a schematic configuration of a battery pack including a cylindrical battery according to an embodiment of the present invention. [Figure 14] 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

[0051] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, the terms and phrases used in the specification and claims should not be construed as being limited to their ordinary and dictionary meanings, but should be construed as having meanings and concepts corresponding to the technical ideas of the present invention, in accordance with the principle that the inventors themselves can appropriately define the concepts of terms in order to best describe the invention.

[0052] Therefore, it should be understood that the embodiments described in this specification and the configurations shown in the drawings are merely the most preferred embodiments of the present invention and do not represent the entire technical idea of ​​the present invention, and that there may be various equivalents and modifications that can be substituted therefor at the time of this application.

[0053] In addition, 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.

[0054] The expression that two comparison objects are identical means that they are "substantially identical." Therefore, "substantially identical" may include deviations that are considered low in the art, for example, deviations within 5%. Furthermore, the expression that a parameter is uniform in a given region means that the parameter is uniform on average in that region.

[0055] Furthermore, although terms such as "first" and "second" are used to indicate various components, these terms are not intended to limit the components. These terms are merely used to distinguish one component from another, and unless otherwise specified, the first component can also be the second component.

[0056] Throughout the specification, unless otherwise stated, each element may be singular or plural.

[0057] When an arbitrary structure is disposed "on (or under)" a component or "above (or below)" a component, it means not only that the arbitrary structure is disposed in contact with the upper surface (or lower surface) of the component, but also that other structures may be interposed between the component and the arbitrary structure disposed above (or below) the component.

[0058] Furthermore, when a component is referred to as being "coupled," "coupled," or "connected" to another component, it does not only mean that the components are directly coupled or connected to each other, but also that other components are "interposed" between the components, or that each component is "coupled," "coupled," or "connected" through other components.

[0059] Throughout the specification, unless otherwise specified, "A and / or B" means A, B, or A and B, and "C to D" means C or more and D or less, unless otherwise specified.

[0060] For ease of explanation, in this specification, the direction along the length of the winding shaft of the electrode assembly wound into a jelly roll is referred to as the axial direction (Y-axis direction). The direction surrounding the winding shaft is referred to as the circumferential direction or outer circumferential direction (X-axis direction). The direction approaching or moving away from the winding shaft is referred to as the radial direction. Of these, the direction approaching the winding shaft is particularly referred to as the centripetal direction, and the direction moving away from the winding shaft is particularly referred to as the centrifugal direction.

[0061] A cylindrical battery according to an embodiment of the present invention includes electrode terminals attached to through-holes formed in the bottom of a battery housing.

[0062] FIG. 5 is a cross-sectional view showing a fixing structure of an electrode terminal 50 according to an embodiment of the present invention, and FIG. 6a is an enlarged cross-sectional view of a portion circled by a dotted line in FIG.

[0063] 5 and 6a, the electrode terminal 50 includes a body portion 50a including an upper surface, a lower surface, and an outer surface, an outer flange portion 50b extending from the outer surface of the body portion 50a along the outer surface 52a of the bottom portion 52 of the battery housing 51, and an inner flange portion 50c extending from the outer surface of the body portion 50a so that at least a portion of the inner flange portion 50c faces the inner surface 52b of the bottom portion 52 of the battery housing 51. The upper surface of the body portion 50a is flat and can be connected to a current collector, and is located above the inner flange portion 50c.

[0064] The fixing structure for the electrode terminal 50 according to one embodiment of the present invention may be applied to a cylindrical battery housing 51. Specifically, the fixing structure for the electrode terminal 50 may include a battery housing 51 having one open side, an electrode terminal 50 fixed through a through-hole 53 formed in a bottom 52 of the battery housing 51, and a terminal gasket 54 interposed between the electrode terminal 50 and the through-hole 53.

[0065] The battery housing 51 may include a cylindrical side wall and a bottom 52 connected to an end of the side wall. A through hole 53 is formed in the bottom 52, so that the battery housing 51 has a structure in which one side is open and the other side is partially closed by the bottom 52. The battery housing 51 may have other shapes besides a cylindrical shape, for example, a rectangular shape having a square cross section.

[0066] The battery housing 51 is made of a conductive metal material. For example, the battery housing 51 may be made of a steel material, but the present invention is not limited thereto. The inner and outer surfaces of the battery housing 51 may be coated with a Ni plating layer.

[0067] The electrode terminal 50 is made of a conductive metal material. For example, the electrode terminal 50 may be made of aluminum, but the present invention is not limited to this. The electrode terminal 50 may be made of a 10-series aluminum alloy, which is easy to plastically process and has low resistance. Plastic processing is a method of applying physical force to metal to deform it into a desired shape, and may include riveting, caulking, etc.

[0068] The terminal gasket 54 may be made of an insulating and elastic polymer resin. For example, the terminal gasket 54 may be made of polypropylene, polybutylene terephthalate, polyethylene fluoride, or the like, but the present invention is not limited thereto.

[0069] Preferably, the electrode terminal 50 is attached to the through-hole 53 so as not to come into contact with the inner wall of the through-hole 53 .

[0070] The electrode terminal 50 includes a main body portion 50a inserted into the through-hole 53. The main body portion 50a may include an upper surface, a lower surface, and an outer surface connecting the upper surface and the lower surface.

[0071] The electrode terminal 50 may include an external flange portion 50b extending from the periphery of a first side of the main body portion 50a exposed from the outer surface 52a of the bottom 52 of the battery housing 51 along the outer surface 52a, and an internal flange portion 50c extending from the periphery of a second side of the main body portion 50a exposed from the inner surface 52b of the bottom 52 of the battery housing 51 so that at least a portion of the internal flange portion 50c faces the inner surface 52b.

[0072] The electrode terminal 50 may include a flat portion 50d on the inside of the inner flange portion 50c. The flat portion 50d is an example of a welded portion. A welded portion is a portion that is welded to another member. The flat portion 50d may be surrounded by the inner flange portion 50c.

[0073] The flat portion 50d corresponds to the upper surface of the main body portion 50a. The flat portion 50d may include a flat surface in at least a partial region. At least a partial region of the flat portion 50d may be parallel to the inner surface 52b of the bottom portion 52 of the battery housing 51. Here, "parallel" means that they are substantially parallel when observed visually. The flat portion 50d may be a surface that was already formed before the electrode terminal 50 was subjected to plastic processing. In other words, the flat portion 50d may be a region that is not deformed by plastic processing.

[0074] Preferably, the electrode terminal 50 is made of metal, and the inner flange portion 50c may be formed by plastically processing the upper outer edge of the body portion 50a. The plastic processing may be caulking, but the present invention is not limited thereto. In one embodiment, the electrode terminal 50 may be a rivet terminal riveted through the through-hole 53 by the inner flange portion 50c.

[0075] The inner flange portion 50c extends in a direction away from the bottom portion 52 of the battery housing 51. The angle (θ) between the surface of the inner flange portion 50c facing the bottom portion 52 of the battery housing 51 and the inner surface 52b of the bottom portion 52 of the battery housing 51 may be 0° to 60°.

[0076] The magnitude of the angle (θ) is determined by the strength of the crimping process when the electrode terminal 50 is attached to the through-hole 53 of the battery housing 51. For example, as the crimping strength increases, the angle (θ) may decrease to 0°. If the angle (θ) exceeds 60°, the sealing effect of the terminal gasket 54 may be reduced.

[0077] On the other hand, since the outer flange portion 50b is substantially parallel to the bottom portion 52 of the battery housing 51, the angle between the inner flange portion 50c and the outer flange portion 50b can also be 0° to 60°.

[0078] According to another embodiment, a recess 55 may be provided between the inner flange portion 50c and the flat portion 50d. The recess 55 is a groove recessed in the central axis direction of the main body portion 50a. The groove may have a closed loop shape when viewed along the central axis direction of the main body portion 50a. The recess 55 may have an asymmetric cross-section. For example, the asymmetric cross-section may be substantially V-shaped or U-shaped. The asymmetric cross-section may include a sidewall 55a of the flat portion 50d and an inclined surface 55b connected to the end of the sidewall 55a and formed by the upper surface of the inner flange portion 50c. The outer surface of the main body portion 50a exposed from the sidewall 55a may be referred to as a first surface, and the inclined surface 55b may be referred to as a second surface. The first surface and the second surface are asymmetric. The sidewall 55a may be substantially perpendicular to the inner surface 52b of the bottom 52 of the battery housing 51. "Perpendicular" means substantially perpendicular when observed visually. As will be described later, the side wall 55a may be inclined toward the flat portion 50d. The recessed portion 55 is formed according to the shape of a crimping jig used when the electrode terminal 50 is attached to the through-hole 53 of the battery housing 51 by crimping.

[0079] Preferably, the thickness of the inner flange portion 50c may decrease as it becomes farther from the main body portion 50a of the electrode terminal 50.

[0080] According to another embodiment, the terminal gasket 54 may include an external gasket 54a interposed between the external flange portion 50b and a first plane P1 on which the outer surface 52a of the bottom 52 of the battery housing 51 is located, an internal gasket 54b interposed between the internal flange portion 50c and a second plane P2 on which the inner surface 52b of the bottom 52 of the battery housing 51 is located, and an intermediate gasket 54c interposed between the main body portion 50a and the through hole 53, connecting the external gasket 54a and the internal gasket 54b.

[0081] The outer gasket 54a and / or the inner gasket 54b and / or the middle gasket 54c may have a thickness that varies depending on the location.

[0082] Preferably, the intermediate gasket 54c may have a thickness that varies with location, and the terminal gasket 54 may have a minimum thickness at the intermediate gasket 54c.

[0083] In one embodiment, the thickness of the region of the intermediate gasket 54c adjacent to the first plane P1 may increase as it approaches the first plane P1. Similarly, the thickness of the region of the intermediate gasket 54c adjacent to the second plane P2 may increase as it approaches the second plane P2. Furthermore, the thickness of the central region of the intermediate gasket 54c located between the first plane P1 and the second plane P2 may be uniform.

[0084] Preferably, the thickness of the region of the intermediate gasket 54c interposed between the inner edge 56 of the through hole 53 connected to the inner surface 52b of the bottom 52 of the battery housing 51 and the inner flange portion 50c may be relatively small. Preferably, a point of minimum thickness may be present in the region of the intermediate gasket 54c interposed between the inner edge 56 of the through hole 53 and the inner flange portion 50c. In addition, the inner edge 56 of the through hole 53 may include an opposing surface 57 facing the inner flange portion 50c.

[0085] Meanwhile, the upper and lower ends of the inner wall of the through hole 53, which are perpendicular to the bottom 52 of the battery housing 51, are chamfered (corner cut) to form a tapered surface toward the electrode terminal 50. However, the upper and / or lower ends of the inner wall of the through hole 53 may be modified to have a smooth curved surface having a curvature. In this case, the stress applied to the gasket 54 near the upper and / or lower ends of the inner wall of the through hole 53 can be further alleviated.

[0086] Preferably, the internal gasket 54b forms an angle (θ) of 0° to 60° with the inner surface 52b of the bottom 52 of the battery housing 51 and extends longer than the internal flange portion 50c.

[0087] In yet another embodiment, the height (H1) of the flat portion 50d, measured from the inner surface 52b of the bottom 52 of the battery housing 51, may be the same as or higher than the height (H2) of the end of the internal gasket 54b. Furthermore, the height (H1) of the flat portion 50d, measured from the inner surface 52b of the bottom 52 of the battery housing 51, may be the same as or higher than the height (H3) of the end of the internal flange portion 50c. Here, the height H2 is the maximum height of the end of the internal gasket 54b measured from the inner surface 52b. Furthermore, the height H3 is the maximum height of the upper surface of the internal flange portion 50c measured from the inner surface 52b.

[0088] When the height parameters H1, H2, and H3 satisfy the above conditions, the inner flange portion 50c and the inner gasket 54b can be prevented from interfering with other components.

[0089] Preferably, the height (H3) of the inner flange portion 50c is 0.5 mm to 3.0 mm. If the height (H3) of the inner flange portion 50c is less than 0.5 mm, sufficient sealing performance cannot be ensured. Also, if the height (H3) of the inner flange portion 50c is more than 3 mm, the internal space of the battery housing 51 that can be occupied by the electrode assembly is reduced.

[0090] Preferably, the height (H4) of the electrode terminal 50 is 1.5 mm to 7 mm. The height (H4) of the electrode terminal 50 corresponds to the distance from the lower surface of the outer flange portion 50b to the flat portion 50d. If the height (H4) of the electrode terminal 50 is less than 1.5 mm, it is difficult to increase the height of the inner flange portion 50c to a level that ensures sealing performance due to the thickness of the bottom portion 52 of the battery housing 51. For reference, the thickness of the bottom portion 52 of the battery housing 51 is approximately 0.5 mm to 1 mm. Also, if the height (H4) of the electrode terminal 50 exceeds 7 mm, the internal space of the battery housing 51 that can be occupied by the electrode assembly is reduced, increasing the battery height and correspondingly reducing the energy density per unit volume. If H3 and H4 satisfy the above numerical ranges, sufficient sealing performance of the electrode terminal 50 can be ensured without reducing the internal space of the battery housing 51.

[0091] In another embodiment, the height (H5) of the external flange portion 50b, based on the outer surface 52a of the bottom 52 of the battery housing 51, may be 0.8 mm or more. If the height (H5) of the external flange portion 50b is less than 0.8 mm, the external flange portion 50b may be deformed when the electrode terminal 50 is riveted. The thickness of the external gasket 54a is 0.3 mm or more, taking into consideration insulation and sealing properties. Considering the thickness of the external gasket 54a, if the height of the external flange portion 50b is less than 0.8 mm, the thickness of the external flange portion 50b becomes too thin to ensure sufficient mechanical rigidity. This is particularly serious when the electrode terminal 50 is made of aluminum. Meanwhile, the height of the external flange portion 50b may be appropriately set taking into consideration the space margin above the battery. For example, the height of the external flange portion 50b may be set to 2 mm or less, 3 mm or less, 4 mm or less, or 5 mm or less, but the present invention is not limited thereto.

[0092] In yet another embodiment, at least a portion of the external gasket 54a may be exposed outside the external flange portion 50b of the electrode terminal 50. The purpose of exposing the external gasket 54a is to insulate the electrode terminal 50 from the outer surface 52a, which has the opposite polarity to the electrode terminal 50. To electrically insulate the electrode terminal 50 from the outer surface 52a, the exposed width (G) of the external gasket 54a may be 0.1 mm to 1 mm. If the exposed width (G) is less than 0.1 mm, electrical insulation between the electrode terminal 50 and the outer surface 52a may be broken down in a flat surface during high-rate (C-rate) charging and discharging of 300 A or more. If the exposed width (G) is greater than 1 mm, the electrical insulation effect is not further improved, and instead the area of ​​the outer surface 52a used as the negative electrode region is reduced, thereby reducing the contact area of ​​components (e.g., bus bars) used for electrical connection.

[0093] In yet another embodiment, the diameter of the flat portion 50d of the electrode terminal 50 can be determined in consideration of the weld strength between the current collector and the flat portion 50d. The tensile strength of the weld between the flat portion 50d and the current collector can be at least 2 kgf or more, 5 kgf or more, 6 kgf or more, 7 kgf or more, 8 kgf or more, 9 kgf or more, or 10 kgf or more. It is preferable to select a suitable welding method to maximize the tensile strength of the weld within an allowable range.

[0094] Referring to Figure 6c, the diameter of the weld pattern Wp formed on the flat portion 50d can be a minimum of 2 mm to satisfy the tensile strength requirement of the weld. The diameter of the weld pattern Wp is calculated by multiplying the area (S) of the weld pattern Wp that appears on the surface of the welded portion by the area (πr 2 ), the equivalent diameter of the corresponding circle (2 × (S / π) 0.5 ) The welding pattern Wp may be continuous or discontinuous. The welding pattern Wp does not have to be circular. When the welding pattern Wp is not circular, the converted diameter (maximum value x 2) can be determined from the maximum value of the distance from the center of the flat portion 50d to the edge of the welding pattern Wp.

[0095] The flat portion 50d of the electrode terminal 50 includes a weldable region. The diameter of the weldable region can be 3 mm to 14 mm. If the diameter of the weldable region is smaller than 3 mm, it is difficult to secure a weld pattern with a diameter of 2 mm or more. In particular, when forming a weld pattern using laser welding, it is difficult to secure a weld pattern with a diameter of 2 mm or more due to interference of the laser beam. If the diameter of the weldable region exceeds 14 mm, the diameter of the outer flange portion 50b of the electrode terminal 50 becomes excessively large, making it difficult to secure a sufficient area of ​​the outer surface 52a of the bottom portion 52 of the battery housing to be used as the negative electrode region.

[0096] When considering the diameter conditions of the welding pattern and the diameter conditions of the weldable area, the ratio of the welding pattern area to the area of ​​the weldable area required to ensure a tensile strength of at least 2 kgf is 2.04% (π1 2 / π7 2 )~44.4%(π1 2 / π1.5 2 ) is preferred.

[0097] In another embodiment, the radius (R1) from the center of the main body portion 50a to the periphery of the outer flange portion 50b may be 10% to 70% of the radius (R2) of the bottom portion 52 of the battery housing 51.

[0098] If R1 is small, there is insufficient welding space when welding a component (bus bar) used for electrical connection of the electrode terminal 50. On the other hand, if R1 is large, there is less welding space when welding a component (bus bar) for electrical connection to the outer surface 52a of the bottom 52 of the battery housing 51 excluding the electrode terminal 50.

[0099] By adjusting the ratio R1 / R2 to be between 10% and 70%, an appropriate welding space can be secured between the electrode terminal 50 and the outer surface 52a of the bottom 52 of the battery housing 51.

[0100] Furthermore, the radius (R3) from the center of the main body 50a of the electrode terminal 50 to the periphery of the flat portion 50d can be 4% to 30% of the radius (R2) of the bottom 52 of the battery housing 51 as the reference.

[0101] If R3 is small, there may not be enough welding space when welding the current collector to the flat portion 50d of the electrode terminal 50, reducing the welding area of ​​the electrode terminal 50 and increasing contact resistance. In addition, R3 must be smaller than R1, and if R3 is large, the inner flange portion 50c may become thinner, weakening the force with which the inner flange portion 50c presses the terminal gasket 54, potentially reducing the sealing ability of the terminal gasket 54.

[0102] By adjusting R3 / R2 between 4% and 30%, the welding area between the flat portion 50d of the electrode terminal 50 and the current collector can be sufficiently secured, which not only facilitates the welding process but also reduces the contact resistance in the welding area and prevents a decrease in the sealing ability of the terminal gasket 54.

[0103] According to an embodiment of the present invention, the fixing structure of the electrode terminal 50 can be formed using a crimping jig that moves up and down. First, a preform (not shown) of the electrode terminal 50 is inserted into a through-hole 53 formed in a bottom portion 52 of a battery housing 51, with a terminal gasket 54 interposed therebetween. The preform refers to the electrode terminal before the crimping process is performed.

[0104] Next, a crimping jig is inserted into the inner space of the battery housing 51. The crimping jig has grooves and protrusions corresponding to the final shape of the electrode terminal 50 on the surface facing the preform, in order to press-mold the preform to form the electrode terminal 50.

[0105] Next, the crimping jig is moved downward to press-form the upper portion of the preform, thereby transforming the preform into an electrode terminal 50 that is riveted into the through-hole 53 of the battery housing 51. The pressing depth of the crimping jig can be limited by the flat portion 50d. The flat portion 50d is pre-formed on the main body portion 50a, and the crimping jig has a groove into which the flat portion 50d is recessed. Therefore, when the flat portion 50d contacts the bottom of the groove during press-forming of the preform, the press-forming is stopped. This allows the inner flange portion 50c and the recess portion 55, which are formed through plastic deformation, to be uniformly shaped even during mass production. Furthermore, the flat portion 50d is not deformed or is barely deformed while the preform is pressed by the crimping jig. Therefore, the flat portion 50d can also maintain a uniform shape during mass production. This facilitates the welding process between the flat portion 50d and the current collector, which will be described later, and thereby significantly reduces manufacturing variations.

[0106] While the preform is compressed and deformed by the crimping tool, the outer gasket 54a interposed between the outer flange portion 50b and the outer surface 52a of the bottom 52 of the battery housing 51 is elastically compressed and its thickness is reduced. Furthermore, the portion of the intermediate gasket 54c interposed between the inner edge 56 of the through-hole 53 and the preform is elastically compressed by the inner flange portion 50c, resulting in a greater thickness reduction than other regions. In particular, the area where the thickness of the intermediate gasket 54c is reduced intensively is the area indicated by the dotted circle in Figure 6a. This significantly improves the sealing and hermeticity between the riveted electrode terminal 50 and the battery housing 51.

[0107] Preferably, the terminal gasket 54 is sufficiently compressed so that it is not physically damaged when the preform is riveted through a plastic process known as caulking, and so that the desired sealing strength can be ensured.

[0108] Preferably, the compression ratio of the terminal gasket 54 may be 30% to 90%. The minimum compression ratio corresponds to the minimum level of compression ratio required to ensure the sealing performance of the electrode terminal 50. The maximum compression ratio corresponds to the maximum level of compression ratio that can be achieved without physically damaging the terminal gasket 54.

[0109] As an example, if terminal gasket 54 is made of polybutylene terephthalate, terminal gasket 54 preferably has a compressibility of 50% or greater at the point where it is compressed to its minimum thickness.

[0110] In the present invention, the compression ratio may be defined as the ratio of the thickness change at the maximum compression point to the pre-compression thickness of the terminal gasket 54. The pre-compression thickness of the inner gasket 54b and the pre-compression thickness of the middle gasket 54c may be uniform, and the maximum compression point may be located near the inner edge 56. Preferably, the compression ratio may be calculated based on the uniform thickness of the inner gasket 54b and the middle gasket 54c.

[0111] As another example, when the terminal gasket 54 is made of polyfluoroethylene, the terminal gasket 54 preferably has a compressibility of 60% or more at the point where it is compressed to its minimum thickness. Preferably, the compressibility can be calculated based on the uniform thickness of the inner gasket 54b and the middle gasket 54c.

[0112] As yet another example, when terminal gasket 54 is made of polypropylene, terminal gasket 54 preferably has a compressibility of 60% or more at the point where it is compressed to its minimum thickness. Preferably, the compressibility can be calculated based on the uniform thickness of inner gasket 54b and middle gasket 54c.

[0113] Preferably, the crimping jig is moved up and down at least two times to perform the press-forming of the upper portion of the preform in stages. That is, the preform may be deformed by being press-formed in stages several times. At this time, the pressure applied to the crimping jig may be increased in stages. This distributes the stress applied to the preform over several stages, thereby preventing damage to the terminal gasket 54 during the crimping process. In particular, damage to the intermediate gasket 54c, which is interposed between the inner edge 56 of the through hole 53 and the preform, is minimized when the intermediate gasket 54c is compressed intensively by the inner flange portion 50c.

[0114] After the press molding of the preform using the crimping jig is completed, the crimping jig is removed from the battery housing 51, and the fixed structure of the electrode terminal 50 according to the embodiment of the present invention is obtained as shown in FIG. 6a.

[0115] According to the above-described embodiment, the crimping jig presses the upper part of the preform by moving up and down inside the battery housing 51. In some cases, a conventional rotary jig may be used to press the preform.

[0116] However, the rotary rotation jig rotates at a predetermined angle relative to the central axis of the battery housing 51. Therefore, a rotary rotation jig with a large rotation radius may interfere with the inner wall of the battery housing 51. Furthermore, if the battery housing 51 is deep, the length of the rotary rotation jig will also be long. In this case, the rotation radius of the end of the rotary rotation jig becomes large, and the preform may not be press-molded sufficiently. Therefore, press molding using a crimping jig is more effective than a method using a rotary rotation jig.

[0117] Meanwhile, the electrode terminal 50 may have various structures depending on the design of the preform and / or the crimping jig and / or the terminal gasket 54 and the amount of pressure applied to the preform during the crimping process.

[0118] FIG. 6b is a partially enlarged cross-sectional view showing the structure of an electrode terminal 50' according to another embodiment of the present invention.

[0119] Referring to FIG. 6 b , an electrode terminal 50 ′ according to another embodiment has a structure in which an inner flange portion 50 c is riveted toward an inner surface 52 b of a bottom portion 52 of a battery housing 51 .

[0120] The inner flange portion 50c includes a first section 5c1 extending away from the bottom 52 of the battery housing 51, and a second section 5c2 connected to the first section 5c1 and extending toward the bottom 52 of the battery housing 51.

[0121] The angle (δ) between the surface of the second section 5c2 facing the bottom 52 of the battery housing 51 and the inner surface 52b of the bottom 52 may be 0° to 30°.

[0122] Preferably, the angle (δ) is substantially close to 0 to maximize the sealing performance of the terminal gasket 54. The second section 5c2 strongly presses the inner gasket 54b, thereby increasing the sealing performance of the terminal gasket 54. This effect is enhanced as the angle (δ) approaches 0.

[0123] The height (H3) of the inner flange portion 50c is greater than the height (H2) of the inner gasket 54b. The inner edge of the through-hole 53 has an arc shape with a predetermined curvature. The side wall 55a at the periphery of the flat portion 50d is inclined toward the flat portion 50d.

[0124] The terminal gasket 54 may include an external gasket 54a interposed between the external flange portion 50b and a first plane P1 on which the outer surface 52a of the bottom 52 of the battery housing 51 is located, an internal gasket 54b interposed between the internal flange portion 50c and a second plane P2 on which the inner surface 52b of the bottom 52 of the battery housing 51 is located, and an intermediate gasket 54c interposed between the main body portion 50a and the through hole 53, connecting the external gasket 54a and the internal gasket 54b.

[0125] Preferably, the thickness of the middle gasket 54c gradually decreases in the direction away from the outer gasket 54a. The inner gasket 54b may decrease to a minimum thickness near the end of the inner flange portion 50c and then increase slightly in thickness toward the top end. This compressible structure of the inner gasket 54b may further improve the sealing performance of the electrode terminal 50'. The compressibility of the inner gasket 54b may be calculated at the minimum thickness point near the end of the inner flange portion 50c.

[0126] Meanwhile, according to the inventors' experiments, when a cylindrical battery to which the electrode terminals 50, 50' are applied is subjected to repeated thermal shock cycle experiments, a gap occurs between the terminal gasket 54 and the electrode terminals 50, 50', causing electrolyte leakage to the outside.

[0127] The thermal shock cycle test involves repeatedly exposing a cylindrical battery to temperatures ranging from -30°C to 60°C after adjusting the charge state of the battery to 50%.

[0128] In each thermal shock cycle, the minimum temperature was maintained for 60 minutes, and the maximum temperature was also maintained for 60 minutes. The rate of temperature change from the minimum temperature to the maximum temperature or from the maximum temperature to the minimum temperature was set to 2.5°C per minute or less. The thermal shock cycle for the cylindrical battery was repeated a total of 200 times.

[0129] FIG. 6d is a photograph of the surface of the cylindrical battery with the electrode terminals 50, 50' exposed after the thermal shock cycle test. Unevenness was observed on the surface of the cylindrical battery. This unevenness confirmed electrolyte leakage. Analysis of the components of the unevenness confirmed that they were electrolyte components.

[0130] FIG. 6e is a photograph showing the measurement results of the gap between the terminal gasket 54 and the electrode terminals 50, 50' before and after the thermal shock cycle test.

[0131] 6e(a) is a cross-sectional photograph of the electrode terminals 50, 50′ and the terminal gasket 54 taken before the thermal shock cycle test. The distance between the corner of the through hole to which the electrode terminals 50, 50′ were attached and the electrode terminals 50, 50′ was measured to be 0.25 mm to 0.35 mm.

[0132] Figure 6e (b) shows cross-sectional photographs of the electrode terminals 50, 50' and the terminal gasket 54 taken at four locations after a thermal shock cycle test. The distance between the corners of the through-holes where the electrode terminals 50, 50' are attached and the electrode terminals 50, 50' increases from 0.264 mm to 0.409 mm, and a gap is also observed at the interface between the battery housing and the terminal gasket 54.

[0133] The increase in the spacing and the presence of gaps were analyzed as the cause of electrolyte leakage. After the thermal shock cycle experiment, the weight of the cylindrical battery decreased. The amount of electrolyte leakage estimated from the weight loss of the cylindrical battery was approximately 180 mg to 270 mg.

[0134] FIG. 6f is a cross-sectional view showing the structure of electrode terminals 50, 50' improved to solve the electrolyte leakage problem confirmed in the thermal shock cycle experiment.

[0135] The improved structure of the electrode terminal can also be applied to the embodiment shown in FIG. 6a.

[0136] A first hot melt layer HM1 may be interposed between the electrode terminals 50, 50' and the terminal gasket .

[0137] A second hot melt layer HM2 may be interposed between the cell housing and the terminal gasket 54.

[0138] Either the first hot melt layer HM1 or the second hot melt layer HM2 may be omitted.

[0139] The hot melt layer may have a thickness of several μm to several hundred μm.

[0140] The first hot melt layer HM1 is interposed at the interface between the inner flange portion 50c and the inner gasket 54b, and at least a portion of the first hot melt layer HM1 can be exposed.

[0141] The first hot melt layer HM1 is interposed between the outer flange portion 50b and the outer gasket 54a, and at least a portion of the first hot melt layer HM1 may be exposed.

[0142] The second hot melt layer HM2 is interposed at the interface between the outer gasket 54a and the first plane P1, and at least a portion of the second hot melt layer HM2 can be exposed.

[0143] The second hot melt layer HM2 is interposed at the interface between the inner gasket 54b and the second plane P2, and at least a portion of the second hot melt layer HM2 can be exposed.

[0144] The first hot melt layer HM1 and the second hot melt layer HM2 can be formed using a hot melt film or a hot melt coating liquid. The hot melt film can be locally attached to the surface of at least one of the two members between which the first hot melt layer HM1 and / or the second hot melt layer HM2 are sandwiched. The hot melt coating liquid can be locally sprayed onto the surface of at least one of the two members between which the first hot melt layer HM1 and / or the second hot melt layer HM2 are sandwiched. The sprayed hot melt coating liquid forms a hot melt coating layer on the surface.

[0145] As an example, the hot melt film may be locally attached to the surface of the terminal gasket 54 that faces the electrode terminal 50 and / or the surface that faces the battery housing 51 .

[0146] As another example, the hot melt coating liquid may be locally sprayed onto the surface of the terminal gasket 54 that faces the electrode terminals 50 , 50 ′ and / or the surface that faces the battery housing 51 .

[0147] As yet another example, a hot melt film may be attached to the surface of the electrode terminals 50, 50' facing the terminal gasket 54. Alternatively, a hot melt coating liquid may be sprayed onto the surface of the electrode terminals 50, 50' facing the terminal gasket 54.

[0148] As yet another example, a hot melt film may be attached to the surface of the battery housing 51 facing the terminal gasket 54. Alternatively, a hot melt coating liquid may be sprayed onto the surface of the battery housing 51 facing the terminal gasket 54.

[0149] The first hot melt layer HM1 and the second hot melt layer HM2 can be formed by heating a hot melt film or a hot melt coating layer, which can be hardened by heating.

[0150] The first hot melt layer HM1 and the second hot melt layer HM2 may be formed from any known hot melt material known in the art, including, without limitation, silicone-based, epoxy-based, acrylic-based, and urethane-based materials.

[0151] The first hot melt layer HM1 and the second hot melt layer HM2 fill in the minute irregularities that exist at the interface between the terminal gasket 54 and the electrode terminals 50, 50', and at the interface between the terminal gasket 54 and the battery housing, thereby improving the sealing properties of the terminal gasket 54 and particularly preventing the terminal gasket 54 from lifting up (interface peeling).

[0152] This prevents electrolyte leakage even when the cylindrical battery is repeatedly charged and discharged in a low-temperature or high-temperature environment.

[0153] Preferably, the fixing structure of the electrode terminals 50, 50' according to the above-described embodiment of the present invention can be applied to cylindrical batteries with a form factor larger than 2170.

[0154] In recent years, as cylindrical batteries are applied to electric vehicles, the form factor of cylindrical batteries has increased compared to conventional 1865, 2170, etc. The increase in form factor brings about an increase in energy density, increased safety against thermal runaway, and improved cooling efficiency.

[0155] In addition, as will be described later, a cylindrical battery employing the electrode terminal 50, 50' fixing structure can perform electrical wiring on only one side. In addition, the electrode terminals 50, 50' have a large cross-sectional area and low resistance, making them highly suitable for fast charging.

[0156] Preferably, the cylindrical battery to which the electrode terminal 50, 50' structure of the present invention is applied may be a cylindrical battery having, for example, a form factor ratio (defined as the value obtained by dividing the diameter of a cylindrical battery by its height, i.e., the ratio of height (H) to diameter (Φ)) of greater than about 0.4.

[0157] Here, the form factor refers to a value indicating the diameter and height of a cylindrical battery. Form factors of a cylindrical battery according to an embodiment of the present invention may be, for example, 4611, 4875, 48110, 4880, or 4680. In the form factor number, the first two digits indicate the diameter of the battery, and the remaining digits indicate the height of the battery.

[0158] A battery according to one embodiment of the present invention may be a cylindrical battery with a diameter of about 46 mm, a height of about 110 mm, and a form factor ratio of 0.418.

[0159] Another embodiment of the battery may be a cylindrical battery having a diameter of about 48 mm, a height of about 75 mm, and a form factor ratio of 0.640.

[0160] In yet another embodiment, the battery may be a cylindrical battery having a diameter of about 48 mm, a height of about 110 mm, and a form factor ratio of 0.436.

[0161] In yet another embodiment, the battery may be a cylindrical battery having a diameter of about 48 mm, a height of about 80 mm, and a form factor ratio of 0.600.

[0162] In yet another embodiment, the battery may be a cylindrical battery having a diameter of about 46 mm, a height of about 80 mm, and a form factor ratio of 0.575.

[0163] Conventionally, batteries with a form factor ratio of approximately 0.4 or less have been used. For example, 1865 and 2170 batteries have been used. The 1865 battery has a diameter of approximately 18 mm, a height of approximately 65 mm, and a form factor ratio of 0.277. The 2170 battery has a diameter of approximately 21 mm, a height of approximately 70 mm, and a form factor ratio of 0.300.

[0164] FIG. 7a is a cross-sectional view of a cylindrical battery 70 according to one embodiment of the present invention cut along the longitudinal direction (Y-axis direction).

[0165] Referring to FIG. 7a, a cylindrical battery 70 according to this embodiment includes a jelly-roll-type electrode assembly 71 in which sheet-like first and second electrodes are wound with a separator interposed therebetween, and in which an uncoated portion 72 of the first electrode is exposed at the bottom as a first part of the first electrode, and an uncoated portion 73 of the second electrode is exposed at the top as a second part of the second electrode.

[0166] Here, the first and second portions may not be the uncoated portions but may be other portions of the electrodes. The other portions may be metal tabs electrically connected to the uncoated portions of the electrodes. Furthermore, the electrode assembly 71 may have other shapes besides a jelly roll shape. Of course, the battery may have other shapes, such as a rectangular shape, in addition to a cylindrical shape.

[0167] In an embodiment, the first electrode may be a negative electrode and the second electrode may be a positive electrode, although the reverse is also possible.

[0168] The method for winding the electrode assembly 71 is substantially the same as the method for winding an electrode assembly used in manufacturing a conventional tabless cylindrical battery described above with reference to FIG.

[0169] In the illustration of the electrode assembly 71, only the uncoated portions 72 and 73 that are exposed and extended to the outside of the separator are shown in detail, and the winding structure of the first electrode, the second electrode and the separator are not shown.

[0170] The cylindrical battery 70 also includes a cylindrical battery housing 51 that houses an electrode assembly 71 and is electrically connected to the uncoated portion 72 of the first electrode.

[0171] Preferably, one side (bottom) of the battery housing 51 is open. The bottom 52 of the battery housing 51 has a structure in which the electrode terminals 50 are riveted into the through-holes 53 through a plastic (e.g., crimping) process.

[0172] Specifically, the electrode terminal 50 may include a main body portion 50a inserted into the through hole 53, an external flange portion 50b extending from the outer periphery of a first side of the main body portion 50a exposed from the outer surface 52a of the bottom 52 of the battery housing 51 along the outer surface 52a, and an internal flange portion 50c extending from the outer periphery of a second side of the main body portion 50a exposed from the inner surface 52b of the bottom 52 of the battery housing 51 toward the inner surface 52b, and optionally further including a flat portion 50d provided inside the internal flange portion 50c and surrounded by the internal flange portion 50c.

[0173] The electrode terminal 50 may be replaced by the structure of the electrode terminal 50' shown in FIG. 6b.

[0174] The cylindrical battery 70 may also include a terminal gasket 54 interposed between the electrode terminal 50 and the through-hole 53 .

[0175] The cylindrical battery 70 may also include a sealing body 74 that seals the open end of the battery housing 51 to be insulated from the battery housing 51. Preferably, the sealing body 74 may include a plate-like cap 74a with no polarity and a sealing gasket 74b interposed between the periphery of the cap 74a and the open end of the battery housing 51.

[0176] The cap 74a may be made of a conductive metal material such as aluminum, steel, nickel, etc. The sealing gasket 74b may be made of an insulating and elastic material such as polypropylene, polybutylene terephthalate, polyethylene fluoride, etc. However, the present invention is not limited by the materials of the cap 74a and the sealing gasket 74b.

[0177] The cap 74a may include a vent notch 77 that ruptures when the internal pressure of the battery housing 51 exceeds a critical value. The vent notch 77 may be formed on both sides of the cap 74a. The vent notch 77 may form a continuous or discontinuous circular pattern, a linear pattern, or other patterns on the surface of the cap 74a. The depth and width of the vent notch 77 may be determined based on the internal pressure of the battery housing 51 exceeding 15 kgf / cm. 2~35kgf / cm 2 The voltage may be set to explode when the voltage is within a range of 0.5 V.

[0178] To secure the seal 74, the battery housing 51 may include a crimping portion 75 that extends inside the battery housing 51 and is bent to wrap around and secure the periphery of the cap 74a together with the sealing gasket 74b.

[0179] Preferably, the lower surface of cap 74a can be positioned higher than the lower end of crimping portion 75. This forms a vent space below cap 74a, allowing gas to be smoothly discharged when vent notch 77 ruptures.

[0180] The battery housing 51 may also include a beading portion 76 pressed into the inside of the battery housing 51 in the area adjacent to the open end. The beading portion 76 supports the periphery of the seal 74, particularly the outer peripheral surface of the sealing gasket 74b, when the seal 74 is secured by the crimping portion 75.

[0181] The cylindrical battery 70 may further include a first current collector 78 welded to the uncoated portion 72 of the first electrode. The first current collector 78 is made of a conductive metal material such as aluminum, steel, or nickel. Preferably, at least a portion 78a of the periphery of the first current collector 78 that does not contact the uncoated portion 72 of the first electrode is interposed between the beading portion 76 and the sealing gasket 74b and secured by the crimping portion 75. Alternatively, at least a portion 78a of the periphery of the first current collector 78 may be secured to the inner circumferential surface 76a of the beading portion 76 adjacent to the crimping portion 75 by welding.

[0182] The cylindrical battery 70 may also include a second current collector 79 welded to the uncoated portion 73 of the second electrode. Preferably, at least a portion of the second current collector 79, for example, a central portion 79a, may be welded to the flat portion 50d of the electrode terminal 50.

[0183] Preferably, when welding the second current collector 79, a welding tool can be inserted through a cavity 80 in the core of the electrode assembly 71 to reach the welding point of the second current collector 79. Furthermore, when the second current collector 79 is welded to the flat portion 50d of the electrode terminal 50, the electrode terminal 50 supports the welding area of ​​the second current collector 79, applying strong pressure to the welding area and improving welding quality. Furthermore, the flat portion 50d of the electrode terminal 50 has a large area, ensuring a large welding area. This reduces the contact resistance of the welding area and therefore the internal resistance of the cylindrical battery 70. The face-to-face welding structure between the riveted electrode terminal 50 and the second current collector 79 is very useful for fast charging using a high C-rate current. This is because it reduces the current density per unit area in the cross section in the current flow direction, thereby reducing the amount of heat generated in the current path compared to conventional methods.

[0184] When welding the flat portion 50d of the electrode terminal 50 to the second current collector 79, any one of laser welding, ultrasonic welding, spot welding, and resistance welding may be used.

[0185] For example, when the flat portion 50d and the second current collector 79 are welded by a laser in a continuous or discontinuous arc pattern, the diameter of the arc weld pattern may be 2 mm or more, preferably 4 mm or more. If the diameter of the arc weld pattern satisfies the required conditions, the tensile strength of the weld can be increased to 2 kgf or more to ensure sufficient weld strength.

[0186] As another example, when the flat portion 50d and the second current collector 79 are ultrasonically welded in a circular pattern, the diameter of the circular weld pattern is preferably 2 mm or more. If the diameter of the circular weld pattern satisfies the relevant conditions, the tensile strength of the weld can be increased to 2 kgf or more to ensure sufficient weld strength.

[0187] The diameter of the flat portion 50d, which corresponds to the weldable area, can be adjusted within a range of 3 mm to 14 mm. If the radius of the flat portion 50d is smaller than 3 mm, it is difficult to form a welding pattern with a diameter of 2 mm or more using a laser welding tool, ultrasonic welding tool, etc. Also, if the radius of the flat portion 50d exceeds 14 mm, the electrode terminal 50 becomes excessively large, reducing the area occupied by the outer surface 52a of the bottom 52 of the battery housing 51, making it difficult to connect an electrical connection part (bus bar) through the outer surface 52a.

[0188] Preferably, the diameter of the weld pattern is 2 mm or more to ensure a tensile force of 2 kgf or more at the welded portion, and the diameter of the weldable area is 3 mm to 14 mm, so the ratio of the weld pattern area to the area of ​​the weldable area is 2.04 (100 × π1 2 / π7 2 )%~44.4(100×π1 2 / π1.5 2 )%.

[0189] The cylindrical battery 70 may further include an insulator 80. The insulator 80 may be interposed between the second current collector 79 and the inner surface 52b of the bottom 52 of the battery housing 51, and between the inner circumferential surface 51a of the side wall of the battery housing 51 and the electrode assembly 71.

[0190] Preferably, the insulator 80 may include a welding hole 80a that exposes the flat portion 50d of the electrode terminal 50 to the second current collector 79. The welding hole 80a may also expose the inner flange portion 50c and the inner gasket 54b together with the flat portion 50d of the electrode terminal.

[0191] Preferably, the insulator 80 covers at least the surface of the second current collector 79 and one side (upper) end of the electrode assembly 71. This prevents the second current collector 79, which has a polarity different from that of the battery housing 51, from coming into contact with the uncoated portion 73 of the second electrode.

[0192] Preferably, the insulator 80 is made of insulating resin and may include an upper plate 80b and a side sleeve 80c. For example, the upper plate 80b and the side sleeve 80c may be an integral injection-molded product. Alternatively, the side sleeve 80c may be replaced with insulating tape. The insulating tape may cover the outer edge of the second current collector 79 as well as the uncoated portion 73 of the second electrode exposed from the outer circumferential surface of the electrode assembly 71.

[0193] Preferably, the insulator 80 and the inner surface 52b of the bottom 52 of the battery housing 51 are closely fitted to each other, as shown in Fig. 7b. Here, "closely fitted" means that there is no gap visible to the naked eye. To eliminate the gap, the distance from the inner surface 52b of the bottom 52 of the battery housing 51 to the flat portion 50d of the electrode terminal 50 may be equal to or slightly smaller than the thickness of the insulator 80.

[0194] Preferably, the uncoated portion 72 of the first electrode and / or the uncoated portion 73 of the second electrode may be bent in the radial direction of the electrode assembly 71, for example, from the outer periphery toward the core, to form bent surfaces at the top and bottom of the electrode assembly 71. In addition, the first current collector 78 may be welded to the bent surface formed by bending the uncoated portion 72 of the first electrode, and the second current collector 79 may be welded to the bent surface formed by bending the uncoated portion 73 of the second electrode.

[0195] To alleviate stresses that occur when the uncoated portions 72, 73 are bent, the first electrode and / or the second electrode may have an improved structure that differs from conventional electrodes (see FIG. 1).

[0196] FIG. 8 is a plan view showing an example of the structure of an electrode 90 according to a preferred embodiment of the present invention.

[0197] Referring to FIG. 8, the electrode 90 includes a sheet-like current collector 91 made of a foil of a conductive material, an active material layer 92 formed on at least one surface of the current collector 91, and a plain portion 93 on the long edge of the current collector 91 where no active material is coated.

[0198] Preferably, the plain portion 93 may include a plurality of notched segments 93a. The plurality of segments 93a may be arranged in a plurality of groups, and the segments 93a in each group may have the same height (length in the Y direction), width (length in the X direction), and / or spacing pitch. The number of segments 93a in each group may be greater or less than that shown in the figure. The segments 93a have a geometric shape formed by combining at least one straight line and / or at least one curved line. Preferably, the segments 93a may be trapezoidal, but may be modified into any shape, including, without limitation, a rectangle, a parallelogram, a semicircle, or a semi-ellipse.

[0199] Preferably, the height of the segment 93a increases stepwise along a direction parallel to the winding direction of the electrode assembly, for example, from the core side to the outer periphery. The core-side uncoated region 93' adjacent to the core side may not include the segment 93a, and the height of the core-side uncoated region 93' may be lower than the other uncoated regions. The outer periphery uncoated region 93'' adjacent to the outer periphery may not include the segment 93a, and the height of the outer periphery uncoated region 93'' may be lower than the other uncoated regions.

[0200] Optionally, the electrode 90 may include an insulating coating layer 94 covering the boundary between the active material layer 92 and the uncoated portion 93. The insulating coating layer 94 includes an insulating polymer resin and may optionally further include an inorganic filler. The insulating coating layer 94 prevents the end of the active material layer 92 from contacting the active material layer of the opposite polarity facing the separator and serves to structurally support the folding of the divided piece 93a. Therefore, when the electrode 90 is wound into an electrode assembly, it is preferable that at least a portion of the insulating coating layer 94 be exposed to the outside through the separator.

[0201] FIG. 9 is a cross-sectional view taken along the longitudinal direction (Y-axis direction) of an electrode assembly 100 in which the divided structure of the uncoated portion of the electrode 90 according to an embodiment of the present invention is applied to the first and second electrodes.

[0202] 9, the electrode assembly 100 can be manufactured using the winding method described with reference to FIG. 2. For ease of explanation, the protruding structure of the uncoated portions 72 and 73 extending outward from the separator is shown in detail, and the winding structure of the first electrode, second electrode, and separator is not shown. The uncoated portion 72 protruding downward extends from the first electrode, and the uncoated portion 73 protruding upward extends from the second electrode.

[0203] The varying heights of the uncoated portions 72, 73 are shown only schematically. That is, the heights of the uncoated portions 72, 73 may vary irregularly depending on the cutting position of the cross section. For example, if the side portions of the trapezoidal segment 93a are cut, the height of the uncoated portions in the cross section will be lower than the height of the segment 93a. Therefore, it should be understood that the heights of the uncoated portions 72, 73 shown in the cross-sectional views of the electrode assembly 100 correspond to the average height of the uncoated portions included in each winding turn.

[0204] As shown in FIGS. 10a and 10b, the uncoated portions 72 and 73 may be folded radially from the outer periphery toward the core of the electrode assembly 100. In FIG. 9, the folded portion 101 is indicated by a dotted box. When the uncoated portions 72 and 73 are folded, adjacent segments overlap each other in the radial direction, forming folded surfaces 102 at the top and bottom of the electrode assembly 100. The core-side uncoated portion (93' in FIG. 8) is too low to be folded. The height (h) of the innermost folded segment is equal to or less than the radial length (r) of the winding region formed by the core-side uncoated portion 93' without a segment structure. Therefore, the cavity 80 in the core of the electrode assembly 100 is not blocked by the folded segments. If the cavity 80 is not blocked, the electrolyte injection process is unaffected and the efficiency of the electrolyte injection is improved. Also, a welding tool can be inserted through the cavity 80 to easily weld the electrode terminal 50 and the second current collector 79 together.

[0205] In the cylindrical battery 70 according to an embodiment of the present invention, the cap 74a of the sealed body 74 does not have polarity. Instead, because the first current collector 78 is connected to the side wall of the battery housing 51, the outer surface 52a of the bottom 52 of the battery housing 51 has the opposite polarity to the electrode terminal 50. Therefore, when connecting multiple batteries in series and / or parallel, wiring such as bus bar connection can be performed at the top of the cylindrical battery 70 using the outer surface 52a of the bottom 52 of the battery housing 51 and the electrode terminal 50. This increases the number of batteries that can be installed in the same space, improving energy density and facilitating electrical wiring work.

[0206] FIG. 11 is a diagram showing a state in which cylindrical batteries 70 according to an embodiment of the present invention are electrically connected using bus bars 150.

[0207] 11, a plurality of cylindrical batteries 70 may be connected in series and parallel at the top using bus bars 150. The number of cylindrical batteries 70 may be increased or decreased depending on the capacity of the battery pack.

[0208] In each cylindrical battery 70, the electrode terminal 50 may have a positive polarity and the outer surface 52a of the bottom 52 of the battery housing 51 may have a negative polarity, or vice versa.

[0209] Preferably, the cylindrical batteries 70 may be arranged in a plurality of columns and rows. The columns are arranged vertically in the drawing, and the rows are arranged horizontally in the drawing. To maximize space efficiency, the cylindrical batteries 70 may be arranged in the closest packing structure. The closest packing structure is formed when an equilateral triangle is drawn when the centers of the electrode terminals 50 are connected to each other.

[0210] Preferably, the bus bars 150 may be disposed on top of the plurality of cylindrical batteries 70, more preferably between adjacent columns. Alternatively, the bus bars 150 may be disposed between adjacent rows.

[0211] Preferably, the bus bars 150 connect the batteries arranged in the same row in parallel to each other, and connect the batteries arranged in two adjacent rows in series to each other.

[0212] Preferably, 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.

[0213] The body portion 151 may extend between the electrode terminals 50 of adjacent cylindrical batteries 70, preferably between rows of cylindrical batteries 70. Alternatively, the body portion 151 may extend along the rows of cylindrical batteries 70, but may be folded regularly, such as in a zigzag shape.

[0214] The plurality of first bus bar terminals 152 may protrude from one side of the body portion 151 toward the electrode terminals 50 of each cylindrical battery 70 and be electrically coupled to the electrode terminals 50. The electrical coupling to the electrode terminals 50 may be performed by laser welding, ultrasonic welding, or the like. The plurality of second bus bar terminals 153 may protrude from the other side of the body portion 151 toward the outer surface 52a of the bottom 52 of the battery housing 51 of each cylindrical battery 70 and be electrically coupled to the outer surface 52a. The electrical coupling to the outer surface 52a may be performed by laser welding or ultrasonic welding.

[0215] 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 an aluminum plate or a copper plate, but the present invention is not limited thereto. Alternatively, the body portion 151, the plurality of first bus bar terminals 152, and the plurality of second bus bar terminals 153 may be fabricated as separate pieces and then joined together by welding or the like.

[0216] In the cylindrical battery 70 according to an embodiment of the present invention, the electrode terminal 50 having a positive polarity and the outer surface 52a of the bottom 52 of the battery housing 51 having a negative polarity are positioned in the same direction, so that electrical connection between the cylindrical batteries 70 can be easily achieved using the bus bar 150.

[0217] In addition, since the electrode terminals 50 and the outer surface 52a of the cylindrical battery 70 have a large area, a sufficient bonding area for the bus bar 150 can be secured, thereby sufficiently reducing the resistance of the battery pack including the cylindrical battery 70.

[0218] FIG. 12a is a partially enlarged view of the electrical connection portion between the bus bar 150 and the cylindrical battery 70, and FIGS. 12b and 12c are views showing the definition of various parameters for designing the upper and lower limits of the diameter of the electrode terminal 50 and the exposed width of the outer surface 52a, taking into account the size of the bus bar terminals 152 and 153.

[0219] 12a, 12b, and 12c, in the cylindrical battery 70, the diameter (E1) of the electrode terminal 50 and the width (E2) of the ring-shaped outer surface 52a can be adaptively adjusted in consideration of the dimensions of the contact areas of the bus bar terminals 152, 153.

[0220] Here, the width (E2) of the outer side surface 52a is the width of the exposed surface parallel to the surface of the electrode terminal 50. Specifically, the width (E2) of the outer side surface 52a is defined as the width of a line segment connecting two points where a straight line (L1) drawn in a radial direction from the center C of the electrode terminal 50 intersects with the inner and outer boundaries of the outer side surface 52a. The width (E2) of the outer side surface 52a is the width of the flat exposed surface excluding the rounded region present on the periphery of the bottom portion 52 and the exposed region 54a' of the outer gasket 54a.

[0221] When viewed from above, the bottom 52 of the battery housing 51 can be divided into an exposed area 54a' of the electrode terminal 50 and the terminal gasket 54, and a rounded area R at the periphery of the outer surface 52a. The rounded area R is a processed area (see FIGS. 7a and 7b) for smoothly connecting the bottom 52 of the battery housing 51 to the side wall of the battery housing 51, and has a width (R d )

[0222] First busbar terminal 152 of busbar 150 branches out to one side opposite the direction of travel of body portion 151 and is electrically connected to electrode terminal 50. At this time, electrode terminal 50 and first busbar terminal 152 form a first overlapping region (shown by hatching) on ​​a plane, and the first overlapping region has a first width (W1). Here, the first overlapping region is a region where electrode terminal 50 and first busbar terminal 152 overlap on a plane.

[0223] The first width (W1) is defined as the maximum value of the distance between any two points selected at the ends of the first overlapping region. The definition of the first width (W1) applies equally to the case where the first overlapping region includes the center of the electrode terminal 50 (FIG. 12b) and the case where the first overlapping region does not include the center of the electrode terminal 50 (FIG. 12c). Referring to FIGS. 12b and 12c, the distance indicated by W1 corresponds to the maximum value of the distance between any two points selected at the ends of the first overlapping region.

[0224] The second busbar terminal 153 of the busbar 150 extends in the opposite direction to the first busbar terminal 152 with respect to the direction of travel of the body portion 151, and is electrically connected to the outer surface 52a of the bottom portion 52 of the battery housing 51. At this time, the second busbar terminal 153 and the outer surface 52a form a second overlapping region (shown by hatching) on ​​a plane, and the second overlapping region has a second width (W2). Here, the second overlapping region is the region where the outer surface 52a and the second busbar terminal 153 overlap on a plane.

[0225] The second width (W2) is defined as the maximum width between two points where each straight line (L2) intersects with the end of the second overlapping region when multiple straight lines (L2) are drawn from the center C of the electrode terminal 50 through the second overlapping region.

[0226] Preferably, the diameter (E1) of the electrode terminal 50 must be at least equal to or larger than the first width (W1) of the first bus bar terminal 152. This is because the first overlapping area between the first bus bar terminal 152 and the electrode terminal 50 must not exceed the electrode terminal 50 on a plane. Also, the diameter (E1) of the electrode terminal 50 can be increased to its maximum until the distance between the boundary of the electrode terminal 50 and the second bus bar terminal 153 corresponds to the width (G) of the exposed area 54a' of the outer gasket 54a. Therefore, the maximum value of the diameter (E1) of the electrode terminal 50 is "D-2×R d -2×G-2×W2".

[0227] Preferably, the width (E2) of the outer surface 52a is a factor that depends on the diameter (E1) of the electrode terminal 50, and must be at least equal to or larger than the second width (W2) of the second bus bar terminal 153. This allows for the formation of an overlapping region between the second bus bar terminal 153 and the outer surface 52a. The width (E2) of the outer surface 52a is determined by the sum of the outer diameter (D) of the battery housing 51, the diameter (E1) of the electrode terminal 50, the width (2×G) of the exposed region of the outer gasket 54a, and the width (2×R) of the rounded region. d ) is subtracted from the value "D-2 × R d -2×G-E1".

[0228] In conclusion, in the cylindrical battery 70 according to the embodiment of the present invention, the diameter (E1) of the electrode terminal 50 and the width (E2) of the outer surface 52a are preferably designed to satisfy the following relationship:

[0229] [Formula 1] W1≦E1≦D-2R d -2G-2W2 E2=0.5×(D-2R d -2G-E1) (E1: diameter of the electrode terminal 50, E2: width of the outer surface 52a, D: outer diameter of the battery housing 51, R d: width of round region R measured on a plane, G: width of exposed region 54a' of outer gasket 54a, W1: width of first bus bar terminal 152, W2: width of second bus bar terminal 153) In a specific example, when D is 46 mm, W1 and W2 are 6 mm, G is 0.5 mm, and R is 1 mm, the diameter (E1) of the electrode terminal 50 is 6 mm to 31 mm, and the width (E2) of the outer surface 52a is 6 mm to 18.5 mm.

[0230] As another example, when D is 46 mm, W1 and W2 are 6 mm, G is 0.5 mm, and Rd is 1.5 mm, the diameter (E1) of the electrode terminal 50 is 6 mm to 30 mm, and the width (E2) of the outer surface 52a is 6 mm to 18 mm.

[0231] The cylindrical battery 70 according to the above-described embodiment of the present invention has a structure in which resistance is minimized by expanding the welding area through the bent surfaces, multiple current paths using the first current collector, minimizing the length of the current path, etc. The AC resistance of the cylindrical battery 70 measured with a resistance meter between the positive and negative electrodes, i.e., between the electrode terminal 50 and the surrounding flat surface 52a, may be 0.5 mΩ to 4 mΩ, and preferably 1 mΩ to 4 mΩ, which is suitable for fast charging.

[0232] In the present invention, the positive electrode active material coated on the positive electrode and the negative electrode active material coated on the negative electrode may be any active material known in the art without any limitation.

[0233] As an example, the positive electrode active material has the general chemical formula A[A x M y ]O 2+z (A includes at least one element selected from Li, Na, and K; M includes at least one element selected from Ni, Co, Mn, Ca, Mg, Al, Ti, Si, Fe, Mo, V, Zr, Zn, Cu, Al, Mo, Sc, Zr, Ru, and Cr; x≧0, 1≦x+y≦2, −0.1≦z≦2; and the stoichiometric coefficients of x, y, z, and the components included in M ​​are selected to maintain electroneutrality of the compound).

[0234] As another example, the positive electrode active material may be an alkali metal compound xLiM disclosed in U.S. Pat. No. 6,677,082, U.S. Pat. No. 6,680,143, etc. 1 O2-(1-x)Li2M 2 O3(M 1 contains at least one element having an average oxidation state of 3; M 2 contains at least one element having an average oxidation state of 4; 0≦x≦1).

[0235] In yet another example, the positive electrode active material may be a compound represented by the general chemical formula Li a M 1 x Fe 1-x M 2 y P 1-y M 3 z O 4-z (M 1 contains at least one element selected from Ti, Si, Mn, Co, Fe, V, Cr, Mo, Ni, Nd, Al, Mg and Al; M 2 contains at least one element selected from Ti, Si, Mn, Co, Fe, V, Cr, Mo, Ni, Nd, Al, Mg, Al, As, Sb, Si, Ge, V and S; M 3 contains halogen elements, optionally including F; <a≦2、0≦x≦1、0≦y<1、0≦z<1;a、x、y、z、M 1 , M 2 and M 3 wherein the stoichiometric coefficients of the components included are selected to maintain electroneutrality of the compound), or lithium metal phosphate represented by Li3M2(PO4)3, where M comprises at least one element selected from Ti, Si, Mn, Fe, Co, V, Cr, Mo, Ni, Al, Mg, and Al.

[0236] Preferably, the positive electrode active material may contain primary particles and / or secondary particles formed by aggregation of primary particles.

[0237] For example, the negative electrode active material may be a carbon material, lithium metal or a lithium metal compound, silicon or a silicon compound, or tin or a tin compound. Metal oxides such as TiO2 and SnO2, which have a potential of less than 2 V, may also be used as the negative electrode active material. The carbon material may be either low-crystalline carbon or high-crystalline carbon.

[0238] The separator may be a porous polymer film, for example, a porous polymer film made of a polyolefin polymer such as an ethylene homopolymer, a propylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, an ethylene / methacrylate copolymer, etc., either alone or in a laminate. Alternatively, the separator may be a conventional porous nonwoven fabric, for example, a nonwoven fabric made of high-melting-point glass fiber, polyethylene terephthalate fiber, etc.

[0239] At least one surface of the separator may include a coating layer of inorganic particles. Alternatively, the separator itself may be made of a coating layer of inorganic particles. The particles constituting the coating layer may have a structure in which they are bound with a binder so that there is interstitial volume between adjacent particles.

[0240] The inorganic particles may be made of an inorganic material having a dielectric constant of 5 or more. Non-limiting examples of the inorganic particles include Pb(Zr,Ti)O3 (PZT), Pb 1-x La x Zr 1-y Ti y O3(PLZT), PB(Mg3Nb 2 / 3 )O3-PbTiO3 (PMN-PT), BaTiO3, hafnia (HfO2), SrTiO3, TiO2, Al2O3, ZrO2, SnO2, CeO2, MgO, CaO, ZnO, and Y2O3.

[0241] The electrolyte is A + B - where A + Li+ , Na + , K. + or a combination thereof. - is F - , Cl - , Br - , I - , NO3 - , N(CN)2 - , BF4 - , ClO4 - , AlO4 - , AlCl4 - , PF6 - , SbF6 - , AsF6 - , BF2C2O4 - , BC4O8 - , (CF3)2PF4 - , (CF3)3PF3 - , (CF3)4PF2 - , (CF3)5PF - , (CF3)6P - , CF3SO3 - , C4F9SO3 - , CF3CF2SO3 - , (CF3SO2)2N - , (FSO2)2N - , CF3CF2(CF3)2CO - , (CF3SO2)2CH - , (SF5)3C - , (CF3SO2)3C - , CF3(CF2)7SO3 - , CF3CO2 - , CH3CO2 - , SCN - and (CF3CF2SO2)2N - The anion comprises one or more anions selected from the group consisting of:

[0242] The electrolyte may be dissolved in an organic solvent such as propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), dimethyl sulfoxide, acetonitrile, dimethoxyethane, diethoxyethane, tetrahydrofuran, N-methyl-2-pyrrolidone (NMP), ethyl methyl carbonate (EMC), γ-butyrolactone, or a mixture thereof.

[0243] The cylindrical battery 70 according to the above-described embodiment can be used to manufacture a battery pack.

[0244] FIG. 13 is a diagram schematically illustrating the configuration of a battery pack according to an embodiment of the present invention.

[0245] 13, a battery pack 200 according to an embodiment of the present invention includes an assembly of electrically connected cylindrical batteries 201 and a pack housing 202 that accommodates the assembly. The cylindrical batteries 201 are the batteries according to the above-described embodiments. For convenience of illustration, components such as bus bars for electrical connection of the cylindrical batteries 201, a cooling unit, and external terminals are not shown.

[0246] The battery pack 200 is mounted on a vehicle. The vehicle may be, for example, an electric vehicle, a hybrid vehicle, or a plug-in hybrid vehicle. The vehicle may be a four-wheeled vehicle or a two-wheeled vehicle.

[0247] FIG. 14 is a diagram illustrating a vehicle including the battery pack 200 of FIG.

[0248] 14, an automobile V according to an embodiment of the present invention includes a battery pack 200 according to an embodiment of the present invention. The automobile V operates by receiving a supply of power from the battery pack 200 according to an embodiment of the present invention.

[0249] As described above, the present invention has been described using limited embodiments and drawings, but the present invention is not limited thereto, and it goes without saying that various modifications and variations 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. [Explanation of symbols]

[0250] 10 positive electrode 11 Negative electrode 12 Separation membrane 20 Current collector 21 Active material 22 Plain area 30 Current collector 31 Current collector 40 Cylindrical Battery 41 Battery housing 42 Sealed body 43 Crimping section 44 Beading Section 45 Lead 46 Insulators 50 electrode terminal 51 Battery housing 52 Bottom 53 Through hole 54 Terminal gasket 55 Recessed part 56 Inner Edge 57 Opposite Surface 70 Cylindrical Battery 71 Electrode assembly 72 Plain area 73 Plain area 74 Sealed body 75 Crimping section 76 Beading section 77 Vent Notch 78 First current collector 79 Second current collector 80 Insulator 90 electrodes 91 Current collector 92 Active material layer 93 Plain area 94 Insulation coating layer 100 electrode assembly 101 Bent part 102 Bent surface 150 busbar 151 Body 152 Busbar terminal, first busbar terminal 153 Busbar terminal, second busbar terminal 200 battery pack 201 Cylindrical Battery 202 Pack Housing

Claims

1. a battery housing having a bottom portion with one side open and the other side having a through hole; an electrode terminal attached to the through hole so as not to come into contact with an inner wall of the through hole; a terminal gasket interposed between the electrode terminal and the through hole; Including, A fixing structure for an electrode terminal, wherein a hot melt layer is interposed at the interface between the electrode terminal and the terminal gasket or at the interface between the terminal gasket and the battery housing.

2. The electrode terminal is a main body portion inserted into the through hole; an external flange portion extending from the first side of the main body portion along an outer surface of the bottom of the battery housing; an inner flange portion extending from the second side of the main body portion so that at least a portion of the inner flange portion faces the bottom of the battery housing and presses the terminal gasket; The electrode terminal fixing structure according to claim 1 , comprising:

3. The electrode terminal fixing structure according to claim 2 , further comprising a welded portion on the inside of the inner flange portion.

4. The electrode terminal fixing structure according to claim 3 , wherein the welded portion includes a flat surface.

5. The terminal gasket is an outer gasket interposed between the outer flange portion and a first plane on which an outer surface of the bottom of the battery housing is located; an internal gasket interposed between the internal flange portion and a second plane on which the inner surface of the bottom of the battery housing is located; an intermediate gasket interposed between the main body and the through hole and connecting the outer gasket and the inner gasket; The electrode terminal fixing structure according to any one of claims 2 to 4, comprising:

6. The electrode terminal fixing structure according to claim 5 , wherein the hot melt layer is interposed at the interface between the outer gasket and the first plane, and at least a portion of the hot melt layer is exposed.

7. The electrode terminal fixing structure according to claim 5 , wherein the hot melt layer is interposed at the interface between the internal gasket and the second flat surface, and at least a portion of the hot melt layer is exposed.

8. The electrode terminal fixing structure according to claim 5 , wherein the hot melt layer is interposed at an interface between the inner flange portion and the inner gasket, and at least a portion of the hot melt layer is exposed.

9. The electrode terminal fixing structure according to claim 5 , wherein the hot melt layer is interposed at an interface between the outer flange portion and the outer gasket, and at least a portion of the hot melt layer is exposed.

10. 2. The electrode terminal fixing structure according to claim 1, wherein the hot melt layer is formed by curing a hot melt film with heat.

11. 2. The electrode terminal fixing structure according to claim 1, wherein the hot melt layer is formed by thermally curing a hot melt coating layer.

12. 12. The electrode terminal fixing structure according to claim 10, wherein the hot melt layer is made of a hot melt material selected from the group consisting of silicone, epoxy, acrylic, and urethane.

13. an electrode assembly in which a first electrode and a second electrode are wound with a separator interposed therebetween; a battery housing that houses the electrode assembly and is electrically connected to the first electrode; an electrode terminal electrically connected to the second electrode, the electrode terminal being attached through a through hole formed in the bottom of the battery housing so as not to come into contact with an inner wall of the through hole, the electrode terminal including: a main body portion inserted into the through hole; an external flange portion extending from a first side of the main body portion along an outer surface of the bottom of the battery housing; and an internal flange portion extending from a second side of the main body portion so that at least a portion of the internal flange portion faces an inner surface of the bottom of the battery housing; a terminal gasket interposed between the electrode terminal and the through hole; a seal that seals the open end of the battery housing so as to be insulative from the battery housing; Including, A battery, wherein a hot melt layer is interposed at the interface between the electrode terminal and the terminal gasket or at the interface between the terminal gasket and the battery housing.

14. The battery according to claim 13 , wherein the electrode terminal includes a weld portion on the inside of the inner flange portion.

15. The battery of claim 14 , wherein the weld includes a flat surface.

16. A battery pack comprising a plurality of batteries according to any one of claims 13 to 15.

17. 17. A motor vehicle comprising the battery pack of claim 16.

Images