Secondary battery, battery pack including the same, and automobile

Abstract

This specification provides a secondary battery including: an electrode assembly formed by stacking and winding a first electrode, a separator, and a second electrode, wherein the first electrode includes a first electrode current collector and an electrode active material layer provided on the first electrode current collector, and the long side end of the current collector along the winding direction is formed by an uncoated portion of the first electrode where the electrode active material layer is not provided; and a current collector plate provided at one end of the electrode assembly where the uncoated portion of the first electrode is exposed, the current collector plate having a center portion corresponding to a winding core of the electrode assembly; and a current collector plate having one end connected to the center portion and including two or more legs extending toward the outer periphery of the electrode assembly, the center portion including a current collector plate hole.

Description

[Technical field]

[0001] The present invention relates to a secondary battery, a battery pack including the secondary battery, and an automobile.

[0002] This application claims the benefit of the filing date of Korean Patent Application No. 10-2021-0022832, filed with the Korean Intellectual Property Office on February 19, 2021, the entire contents of which are incorporated herein by reference. [Background technology]

[0003] Secondary batteries, which have high applicability to various products 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) that are powered by electrical sources.

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

[0005] Currently, the types of secondary batteries that are widely used include lithium ion batteries, lithium polymer batteries, nickel cadmium batteries, nickel metal hydride batteries, and nickel zinc batteries. The operating voltage of such a unit secondary battery cell, i.e., a unit battery, is about 2.5V to 4.5V. Therefore, when a higher output voltage is required, a battery pack may be configured by connecting a plurality of batteries in series. Also, a battery pack may be configured by connecting a plurality of batteries in parallel according to the charge / discharge capacity required for the battery pack. Therefore, the number of batteries included in the battery pack and the electrical connection form may be set in various ways according to the required output voltage and / or charge / discharge capacity.

[0006] Meanwhile, cylindrical, prismatic and pouch-type batteries are known as types of unit secondary battery cells. In the case of a cylindrical battery, a separator, which is an insulator, is interposed between the positive and negative electrodes, and the electrode assembly is wound up to form a jelly-roll-like electrode assembly, which is then inserted into a battery housing to form a battery. The battery housing is called a battery can in the industry. An electrode tab may be connected to each uncoated portion of the positive and negative electrodes, and the electrode tab electrically connects the electrode assembly to an electrode terminal exposed to the outside.

[0007] However, the electrode tap structure connecting the jelly-roll type electrode assembly and an external terminal has a limited current path, which increases the resistance of the jelly-roll type electrode assembly itself, making it necessary to implement a new current path. Summary of the Invention [Problem to be solved by the invention]

[0008] The present disclosure provides a secondary battery having a structure in which a current path can be shortened when a current collector plate and an electrode assembly are electrically connected, and in which electrolyte injection properties are excellent. [Means for solving the problem]

[0009] One embodiment of the present specification provides a secondary battery including: an electrode assembly formed by stacking and winding a first electrode, a separator, and a second electrode, the first electrode including a first electrode collector and an electrode active material layer provided on the first electrode collector, and a long side end portion along the winding direction of the collector is formed of an uncoated portion of the first electrode on which the electrode active material layer is not provided; and a current collector provided at one end of the electrode assembly where the uncoated portion of the first electrode is exposed, the current collector having a center portion corresponding to a winding core of the electrode assembly; and a current collector having one end connected to the center portion, extending in an outer periphery of the electrode assembly, and including two or more legs electrically connected to the uncoated portion of the first electrode, the center portion including a current collector hole.

[0010] In one embodiment of the present specification, the two or more legs of the current collector plate may be in the form of a one-way, a cross, or a combination of a one-way and a cross.

[0011] In one embodiment of the present specification, each of the two or more legs may be welded to an uncoated portion of the first electrode and electrically connected thereto.

[0012] In one embodiment of the present specification, the current collector plate may have a thickness of 0.15 mm or more and 0.6 mm or less.

[0013] In an embodiment of the present specification, the current collecting plate may further include a terminal connection part electrically connected to the center part.

[0014] In one embodiment of the present specification, the length of the legs may be 25% or more and 50% or less based on 100% of the outer diameter of the secondary battery.

[0015] In one embodiment of the present specification, the width of the legs may be 6% or more and 22% or less based on 100% of the outer diameter of the secondary battery.

[0016] In one embodiment of the present specification, the ratio of the area of ​​the surface of the current collector plate facing the uncoated portion of the first electrode to the area of ​​the surface of the current collector plate where the uncoated portion of the first electrode is in contact with each other may be 10% or more and 99% or less, based on 100% of the area of ​​the surface of the current collector plate facing the uncoated portion of the first electrode.

[0017] The percentage of the area of ​​the surface of the current collector plate facing the uncoated portion of the first electrode in contact with the uncoated portion of the first electrode refers to the area of ​​the surface of the current collector plate facing the uncoated portion of the first electrode that comes into contact with the uncoated portion of the first electrode, expressed as a percentage, based on the area of ​​the surface of the current collector plate facing the uncoated portion of the first electrode.

[0018] In one embodiment of the present specification, the ratio of the area of ​​the surface of the uncoated portion of the first electrode facing the current collector plate to the area of ​​the uncoated portion of the first electrode in contact with the current collector plate may be 10% or more and 99% or less, based on 100% of the area of ​​the surface of the uncoated portion of the first electrode facing the current collector plate.

[0019] The meaning of the percentage of the area of ​​the surface of the uncoated portion of the first electrode facing the current collector plate, where the uncoated portion of the first electrode contacts the current collector plate, is expressed as a percentage of the area of ​​the surface of the uncoated portion of the first electrode facing the current collector plate that contacts the current collector plate.

[0020] In one embodiment of the present specification, the current collector plate may have an aperture ratio defined by the following formula 1 of 20% or more and less than 100%. [Formula 1] Opening ratio (%) = 1 - (area where the current collector plate contacts the top surface of the electrode assembly) / (area of ​​a circle whose diameter is the outer diameter of the electrode assembly) = (area where the current collector plate is not in contact with the top surface of the electrode assembly) / (area of ​​a circle whose diameter is the outer diameter of the electrode assembly)

[0021] In one embodiment of the present specification, the terminal connector may be bent one or more times toward the center of the current collector plate.

[0022] In one embodiment of the present specification, the terminal connection portion may be provided between two adjacent legs.

[0023] In one embodiment of the present specification, a thickness of a connection portion between the terminal connection portion and the current collector plate may be the same as a thickness of the current collector plate.

[0024] In one embodiment of the present specification, the length of the terminal connecting portion may be 20 mm or more and 40 mm or less.

[0025] In one embodiment of the present specification, the width of the terminal connection portion may be 8% or more and 35% or less based on 100% of the outer diameter of the secondary battery.

[0026] In one embodiment of the present specification, the secondary battery further includes: a battery can that houses the electrode assembly and has an opening; a sealing body that is configured to seal the opening of the battery can and includes a cap plate and a sealing gasket, and the terminal connection portion may be coupled to a connection plate attached to the cap plate.

[0027] An embodiment of the present specification provides a battery pack including a plurality of the above-described secondary batteries.

[0028] An embodiment herein provides a vehicle including at least one battery pack as described above. Effect of the Invention

[0029] The secondary battery according to an embodiment of the present specification can reduce resistance by shortening the current path, and can ensure excellent electrolyte injection properties by providing a sufficient space for injection of electrolyte. [Brief description of the drawings]

[0030] [Figure 1] 1 is a plan view showing a structure of an electrode plate used in a secondary battery according to an embodiment of the present specification; [Diagram 2] 1A-1C are diagrams illustrating a winding process of an electrode assembly according to an embodiment of the present disclosure. [Diagram 3] 3 is a diagram showing a process in which a current collector plate is welded to a folded surface of an uncoated portion in the electrode assembly of FIG. 2. [Figure 4] 1 is a cross-sectional view of a secondary battery according to an embodiment of the present specification cut in a longitudinal direction Y. FIG. [Diagram 5] 1 illustrates a current collector plate having a character "1" shape according to an embodiment of the present disclosure. [Figure 6] 1 illustrates a cross-shaped current collector plate according to one embodiment of the present disclosure. [Figure 7] 1 illustrates a current collector having a shape in which a one-shape and a cross shape are mixed, according to an embodiment of the present disclosure. [Figure 8]1 is a diagram showing a coupling structure between a current collector plate and an electrode assembly according to an embodiment of the present specification; [Figure 9] 1 is a diagram showing a coupling structure between a current collector plate and an electrode assembly according to an embodiment of the present specification; [Figure 10] 1 is a diagram showing a coupling structure between a current collector plate and an electrode assembly according to an embodiment of the present specification; [Figure 11] FIG. 2 is a partial cross-sectional view showing a lower structure of a cylindrical secondary battery according to an embodiment of the present specification. [Figure 12] 1 is a plan view illustrating an exemplary electrode structure according to an embodiment of the present specification; [Figure 13] 1 is a cross-sectional view taken along a longitudinal direction Y of an electrode assembly in which a segmented structure of an uncoated portion of an electrode according to an embodiment of the present specification is applied to a first electrode and a second electrode. [Figure 14] 2 is a cross-sectional view of an electrode assembly in which a non-coating portion is folded according to an embodiment of the present specification, taken along a longitudinal direction Y. FIG. [Figure 15] 1 is a diagram showing a schematic configuration of a battery pack including a secondary battery according to an embodiment of the present specification; [Figure 16] FIG. 1 is a diagram showing a schematic configuration of a vehicle including a battery pack according to an embodiment of the present specification. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] This specification will be explained in more detail below.

[0032] Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, the terms or words used in this specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings, but should be interpreted with a meaning and concept that is consistent with the technical idea of ​​the present invention, based on the principle that the inventor can appropriately define the concept of the term in order to describe the invention in the best way. Therefore, the embodiments described in this specification and the configurations shown in the drawings are only some of the most preferred embodiments of the present invention, and do not represent the entire technical idea of ​​the present invention, so it should be understood that there may be various equivalents and modifications that can be substituted for them at the time of this application.

[0033] In addition, in order to facilitate understanding of the invention, the accompanying drawings are not drawn to scale, and the dimensions of some components may be exaggerated, and the same reference numerals may be used to refer to the same components in different embodiments.

[0034] As used herein, "on" does not only mean to be physically on top of a layer, but also to be positioned on top of a layer, i.e., a layer positioned on top of another layer may have other layers therebetween.

[0035] In this specification, when a part is said to "comprise" a certain component, this means that it may further include other components, rather than excluding other components, unless specifically stated to the contrary.

[0036] A secondary battery according to one embodiment of the present specification provides an electrode assembly formed by stacking and winding a first electrode, a separator, and a second electrode, the first electrode including a first electrode collector and an electrode active material layer provided on the first electrode collector, the long side end of the collector along the winding direction being constituted by an uncoated portion of the first electrode where the electrode active material layer is not provided; and a current collector provided at one end of the electrode assembly where the uncoated portion of the first electrode is exposed, the current collector having a center corresponding to a winding core of the electrode assembly; and two or more legs having one end connected to the center, extending in an outer periphery of the electrode assembly, and electrically connected to the uncoated portion of the first electrode, the center including a current collector hole.

[0037] In a conventional secondary battery, the uncoated portions of the electrodes of the electrode assembly are positioned inside a separator to prevent them from being exposed, and as a method for connecting the electrode assembly to an electrode terminal, an electrode tab is connected to each uncoated portion of the positive and negative electrodes, and the electrode tabs electrically connect the electrode assembly to an external electrode terminal. However, the electrode tap structure connecting the jelly roll type electrode assembly to the external electrode terminal has a limited current path, which causes the resistance of the jelly roll type electrode assembly itself to be high. In other words, when a limited number of electrode taps are applied, there is a problem that the current flowing through the current collector plate cannot smoothly exit through the narrow path of the electrode tap.

[0038] The secondary battery of the present invention has a structure in which the uncoated portion of a first electrode is exposed to an upper surface of an electrode assembly and a current collector is provided on one end of the exposed uncoated portion of the first electrode in order to diversify current paths without using a conventional structure in which an electrode tab is connected to an uncoated portion of an electrode or a structure in which the uncoated portion of an electrode is positioned inside a separator so as not to be exposed.

[0039] In this case, the current collecting plate of the present invention includes two or more legs that can be used as a current path, and has a structure in which each leg abuts and is electrically connected to the uncoated portion of the first electrode, creating multiple paths through which current can move from the uncoated portion of the first electrode to the current collecting plate, making it possible to significantly reduce the resistance across the electrode assembly compared to conventional structures.

[0040] As shown in Figures 5 to 7, the legs 30a are connected from the center of the current collector plate, and the leg shapes of the present invention are not limited to those shown in Figures 5 to 7. As an example, Figure 8 shows a structure in which a current collector plate 30 including four legs is provided at one end of an electrode assembly where the uncoated portion of the first electrode is exposed, and the four legs form multiple contact portions between the uncoated portion 10a of the first electrode and the current collector plate.

[0041] In one embodiment of the present specification, the current collector 30 may be made of a metal material having electrical conductivity.

[0042] In one embodiment of the present specification, the current collecting plate 30 may be provided at one end of the electrode assembly where the uncoated portion 10a of the first electrode is exposed. Fig. 9 illustrates a structure in which the current collecting plate 30 is coupled to the end of the uncoated portion 10a of the first electrode when the secondary battery is cut in the longitudinal direction Y, and has a structure in which the current collecting plate is coupled to the end of the uncoated portion of the first electrode.

[0043] In one embodiment of the present specification, the current collector plate 30 and the uncoated portion 10a of the first electrode may be joined by laser welding, spot welding, or ultrasonic welding.

[0044] In one embodiment of the present specification, the current collector plate may be joined on a joining surface (folded surface) formed by folding an end of the uncoated portion of the first electrode one or more times in a direction aligned with the current collector plate. The folding direction of the uncoated portion of the first electrode may be a radial direction of the electrode assembly. The folding direction of the uncoated portion of the first electrode may be, for example, a direction toward a winding shaft of the electrode assembly.

[0045] When the uncoated portion of the first electrode is folded in this manner, the space occupied by the uncoated portion of the first electrode is reduced, leading to improved energy density. In addition, the bonding area between the uncoated portion of the first electrode and the current collector plate is increased, leading to improved bonding strength and reduced contact resistance. Figure 10 illustrates an example of a structure in which the current collector plate is bonded to a bonding surface formed by bending an end of the uncoated portion of the first electrode in a direction parallel to the current collector plate when the secondary battery is cut in the longitudinal direction Y.

[0046] In one embodiment of the present specification, the current collector plate includes a center portion 30e that corresponds to the winding core of the electrode assembly. The center portion corresponding to the winding core of the electrode assembly means that the center portion of the current collector plate is located in the center portion including the winding core of the portion where the uncoated portion of the first electrode of the electrode assembly is exposed as shown in Fig. 8, but does not mean that the size of the center portion of the current collector plate is necessarily equal to the size of the winding core of the electrode assembly.

[0047] In one embodiment herein, the current collector plate includes a current collector plate hole 30c at the center.

[0048] In one embodiment of the present specification, the radius R1 of the current collecting plate hole 30c may be 100% or more and 110%, or may be 100% or more and 107% or less, or may be 100% or more and 105% or less, based on the diameter of the winding core of the electrode assembly being 100%.

[0049] When the above range is satisfied, the injectability of the electrolyte into the electrode assembly can be improved.

[0050] In one embodiment of the present specification, the thickness of the current collector plate may be 0.15 mm or more and 0.6 mm or less, 0.15 mm or more and 0.5 mm or less, or 0.17 mm or more and 0.3 mm or less.

[0051] When the thickness of the current collector is within the above range, the current collector has an appropriate resistance and an appropriate amount of heat while ensuring the welding processability. If the thickness of the current collector is too thick, the resistance is lowered, the amount of heat generated is reduced, and the welding processability is deteriorated. If the thickness of the current collector is too thin, the resistance is higher, the amount of heat generated is increased, and the welding processability is improved.

[0052] In this specification, the leg refers to a portion having one end connected to the center of the current collector plate and extending toward the outer periphery of the electrode assembly.

[0053] In one embodiment of the present specification, the two or more legs of the current collector plate may be in a one-shape, a cross shape, or a mixed one-shape and cross shape.

[0054] In one embodiment of the present specification, the shape of two or more legs of the current collector plate may be a one-shape, a cross shape, or a mixed shape of a one-shape and a cross shape.

[0055] When the current collector plate of the present invention has the above-described configuration, if the number of welded sections is increased when the current collector plate is welded to the uncoated portion of the first electrode, stress is dispersed, thereby reducing resistance to external force applied during welding and electrical resistance, and preventing the current collector plate from bending after welding or floating up due to lack of adhesion to the electrode assembly.

[0056] In one embodiment of the present specification, the thickness of the legs may be 0.15 mm or more and 0.6 mm or less, 0.15 mm or more and 0.5 mm or less, or 0.17 mm or more and 0.3 mm or less, and may be the same as the thickness of the current collecting plate.

[0057] In one embodiment of the present specification, the length of the legs may be 25% to 50%, 30% to 45%, or 30% to 40% of the outer diameter L of the secondary battery (100%). The length of the legs refers to the length from the connection between the legs and the center of the current collector plate to the end of the legs.

[0058] In this specification, the outer diameter of the secondary battery means the maximum distance between the central part of the battery can of the secondary battery, for example, the outer surface of the battery can facing the electrode assembly. In Figures 4 and 8, the outer diameter of the secondary battery is indicated by a dotted line as L.

[0059] In one embodiment of the present specification, the width of the legs may be 6% or more and 22% or less, 8% or more and 20% or less, or 10% or more and 15% or less, based on 100% of the outer diameter of the secondary battery.

[0060] In one embodiment of the present specification, the edge of the leg may be configured in a straight line, a curved line, or a combination of straight lines and curved lines, and may be in a rectangular shape, for example, but is not limited to this.

[0061] In one embodiment herein, the legs may have the same width.

[0062] In one embodiment herein, the width of the legs may decrease or increase in width towards the distal end of the legs.

[0063] In one embodiment of the present specification, the angle formed between the leg and another adjacent leg may be 60° to 180°.

[0064] In one embodiment of the present specification, the angle formed between the leg and another adjacent leg may be 60° to 120°.

[0065] In one embodiment of the present specification, each of the two or more legs may include a welded portion that is welded to the uncoated portion of the first electrode. The welded portion refers to a portion of the current collector that is joined to the uncoated portion of the first electrode by welding.

[0066] In one embodiment of the present specification, each of the two or more legs may be welded to an uncoated portion of the first electrode and electrically connected thereto.

[0067] The leg of the present invention may include a welded portion, and the welded portion of the leg and the portion where the uncoated portion of the first electrode contacts may be welded to be electrically connected to each other. The welding may be performed by laser welding, spot welding, or ultrasonic welding.

[0068] The current collector plate of the present invention has a structure including two or more legs 30 extending from a center portion 30e corresponding to the winding core of the electrode assembly toward the outer periphery of the electrode assembly, and each leg is welded to the uncoated portion of the first electrode.

[0069] 5 to 7 are diagrams illustrating examples of current collector plate configurations with two, four, and six legs, and show welds 30b within the legs.

[0070] In one embodiment of the present specification, the current collector plate includes a leg including two or more welds, and the area of ​​each of the two or more welds may be equal. That is, in the case of a current collector plate having four legs, there are four welds, and the areas of each of the welds may be equal to each other.

[0071] In this case, the statement that the two comparison objects are identical means that they are "substantially identical." Therefore, substantially the same may include cases where there is a deviation that is considered to be a low level in the art, for example, a deviation within 5%.

[0072] In one embodiment of the present specification, the area of ​​the welded portion may be 10% to 50% of the total area of ​​the current collector plate. When the area of ​​the welded portion satisfies this range, the weld strength can be increased, and the combined electrode assembly and current collector plate can have excellent durability.

[0073] In one embodiment of the present specification, the ratio of an area of ​​the current collector plate that is not in contact with the upper surface of the electrode assembly to an area of ​​a circle having a diameter equal to the outer diameter of the electrode assembly may be defined as the aperture ratio of the current collector plate 30. The aperture ratio can be calculated by the following formula. Opening ratio (%) = 1 - (area where the current collector plate contacts the top surface of the electrode assembly) / (area of ​​a circle whose diameter is the outer diameter of the electrode assembly) = (area where the current collector plate is not in contact with the top surface of the electrode assembly) / (area of ​​a circle whose diameter is the outer diameter of the electrode assembly)

[0074] The aperture ratio of the current collector may be, for example, about 20% or more and less than 100%, and preferably about 30% or more and less than 100%. Taking the case where the current collector shown in FIG. 8 is placed on and coupled to the electrode assembly as an example, the region where the current collector contacts the electrode assembly may be a center portion and two or more legs each having one end connected to the center portion and extending toward the outer periphery of the electrode assembly. That is, the ratio of the area where the current collector contacts the electrode assembly to the area of ​​a circle having a diameter the same length as the outer diameter of the electrode assembly may be 80% or less, preferably 70% or less. When the aperture ratio of the current collector is within the above range, impregnation of the electrolyte can be smoothly performed. That is, the electrolyte spreads radially through the region where the current collector does not contact the upper surface of the electrode assembly, moves to the open space, and then seeps into the electrode assembly.

[0075] In one embodiment of the present specification, the ratio of the area of ​​the surface of the current collector plate facing the uncoated portion of the first electrode to the area of ​​the surface where the current collector plate and the uncoated portion of the first electrode contact each other is 10% or more, 15% or more, 20% or more, 30% or more, 40% or more, 50% or more, 70% or more, or 90% or more, and may be 99% or less, 98% or less, 95% or less, or 93% or less, based on 100% of the area of ​​the surface of the current collector plate facing the uncoated portion of the first electrode.

[0076] When this area ratio is satisfied, a large number of paths through which current can move from the uncoated portion of the first electrode to the current collector can be effectively created, thereby reducing the magnitude of resistance across the electrode assembly.

[0077] In one embodiment of the present specification, based on 100% of the area of ​​the uncoated portion of the first electrode facing the current collector plate, the ratio of the area of ​​the uncoated portion of the first electrode and the surface in contact with the current collector plate is 10% or more, 15% or more, 20% or more, 30% or more, 40% or more, 50% or more, 70% or more, or 90% or more, and may be 99% or less, 98% or less, 95% or less, or 93% or less.

[0078] When this area ratio is satisfied, a large number of paths through which current can move from the uncoated portion of the first electrode to the current collector can be effectively created, thereby reducing the magnitude of resistance across the electrode assembly.

[0079] In one embodiment of the present specification, the uncoated portion of the first electrode of the electrode assembly may be present in a portion corresponding to the leg of the current collector plate, and may not be present in a portion not corresponding to the leg of the current collector plate.

[0080] In one embodiment of the present specification, the uncoated portion of the first electrode of the electrode assembly may be cut in the same shape as the current collector plate.

[0081] In one embodiment of the present specification, the folded portion of the uncoated portion of the first electrode of the electrode assembly may be cut in the same shape as the current collector plate.

[0082] In one embodiment of the present specification, the folded portion of the uncoated portion of the first electrode of the electrode assembly may be cut in the same shape as a current collector having two legs, four legs, or six legs, such as the current collectors in Figures 5 to 7.

[0083] In one embodiment of the present specification, the percentage of the area of ​​the leg that is in contact with the uncoated portion of the first electrode, based on 100% of the area of ​​the leg, may be 10% or more, 15% or more, 20% or more, 30% or more, 40% or more, 50% or more, 70% or more or 90% or more, or may be 99% or less, 98% or less, 95% or less, or 93% or less.

[0084] In one embodiment of the present specification, the current collector plate may further include a terminal connector 45 extending outward from the center. By further including the terminal connector, the current collector plate of the present invention not only serves as a current collector plate that collects current, but also serves as an electrode tab that transfers the current to the electrode terminal. Therefore, the number of parts used in manufacturing a secondary battery can be reduced, and a process of welding a separate electrode tab to the uncoated portion or the current collector plate can be omitted, thereby improving process efficiency.

[0085] In one embodiment of the present specification, the terminal connector may be integrally formed with the current collector plate.

[0086] In one embodiment herein, the terminal connection portion may be provided between the leg and an adjacent leg.

[0087] In one embodiment of the present specification, a thickness of a connection portion between the terminal connection portion and the current collector plate may be the same as a thickness of the current collector plate.

[0088] In one embodiment of the present specification, the terminal connector may be bent one or more times toward the center of the current collector plate.

[0089] In one embodiment of the present specification, the terminal connector may be bent two or more times toward the center of the current collector plate.

[0090] The terminal connection portion is located apart from the leg and may be directly connected to a cap plate of a sealing body, which will be described later, or may be combined with a connection plate attached to the cap plate.

[0091] In one embodiment of the present specification, the thickness of the terminal connection portion may be 0.15 mm or more and 0.6 mm or less, 0.15 mm or more and 0.5 mm or less, or 0.17 mm or more and 0.3 mm or less, and may be the same as the thickness of the current collecting plate.

[0092] In one embodiment of the present specification, the length of the terminal connection part may be 20 mm to 40 mm, or 25 mm to 35 mm. The length of the terminal connection part means the length extending from the connection part between the terminal connection part and the center of the current collector plate to the end part of the terminal connection part.

[0093] Since the terminal connector is bent at least once to be coupled to a connecting plate (to be described later), a space is required inside the secondary battery for this purpose. If the above length is satisfied, the space used for coupling the terminal connector to the connecting plate (to be described later) can be used efficiently and wasted space can be minimized, resulting in an increase in the capacity of the secondary battery.

[0094] In one embodiment of the present specification, the width of the terminal connecting portion may be 8% or more and 35% or less, 10% or more and 30% or less, or 10% or more and 25% or less, based on the outer diameter L of the secondary battery (100%).

[0095] When the width is satisfied, when the terminal connection portion is bent one or more times, the space used for connection with the connection plate described below can be efficiently used while maximizing the connection area with the connection plate, for example, the area of ​​the current path, and the problem of internal heat generation during fast charging can be improved.

[0096] The electrode assembly according to an embodiment of the present specification may have, for example, a jelly-roll structure. The electrode assembly may be manufactured by stacking a first electrode and a second electrode having a sheet shape at least once with a separator interposed therebetween, and winding the stack around the center of the stack.

[0097] In one embodiment of the present specification, the first electrode includes a first current collector and an electrode active material layer provided on one or both sides of the first current collector. A long side end along the winding direction of the first current collector provided at one end of a winding shaft of the electrode assembly has an uncoated portion of the first electrode where no electrode active material layer is provided. The uncoated portion of the first electrode is provided at an upper portion in the height direction (direction aligned with the Z axis) of the electrode assembly contained in the battery can. That is, the long side end of the first current collector is not coated with an electrode active material and includes the uncoated portion of the first electrode exposed to the outside of the separator.

[0098] In one embodiment of the present specification, the second electrode includes a second electrode collector and a second electrode active material layer provided on one or both sides of the second electrode collector. At the other end of the second electrode collector in the width direction (direction aligned with the Z axis), there is a plain portion of the second electrode that does not include the second electrode active material layer.

[0099] The uncoated portion of the second electrode is provided at the lower portion in the height direction (direction aligned with the Z-axis) of the electrode assembly housed in the battery can. That is, the second electrode current collector includes a second uncoated portion that is not coated with an electrode active material layer at a long side end and is exposed to the outside of the separator, and at least a portion of the second uncoated portion may be used as an electrode tab by itself. The second uncoated portion may be, for example, a cathode tab.

[0100] In one embodiment herein, the first electrode may be an anode plate and the second electrode may be a cathode plate.

[0101] In one embodiment herein, the first electrode may be a cathode plate and the second electrode may be an anode plate.

[0102] That is, the positive and negative electrode plates have a structure in which an active material 21 is coated on a sheet-shaped current collector 20, and include a non-coated portion 22 on one long side in the winding direction. In this case, an additional separator may be provided on the outer periphery of the electrode assembly 100 for insulation from the battery can 41. Any jelly roll structure known in the art may be applied to the present invention without being limited thereto.

[0103] Fig. 1 shows the structure of a current collector according to an embodiment of the present specification, Fig. 2 shows a winding process of the current collector according to an embodiment of the present specification, Fig. 3 shows a process of welding a current collector plate to the folded surface of the non-coating portion according to an embodiment of the present specification, and Fig. 4 shows the structure of a secondary battery including an electrode assembly, a current collector plate, and a sealed body.

[0104] 1 to 3, the positive electrode plate 10 and the negative electrode plate 11 have a structure in which an active material 21 is coated on a sheet-shaped current collector 20, and include a non-coated portion 22 on one long side along the winding direction X.

[0105] The electrode assembly is fabricated by stacking an anode plate 10 and a cathode plate 11 together with two separators 12 in sequence as shown in Fig. 2, and then winding them up in one direction X. At this time, the uncoated portions of the anode plate 10 and the cathode plate 11 are arranged in opposite directions. After the winding process, the uncoated portion 10a of the anode plate 10 and the uncoated portion 11a of the cathode plate 11 are folded toward the core. Then, the current collector plate 30 and the second current collector plate 31 are welded to the uncoated portions 10a and 11a, respectively.

[0106] No separate electrode tabs are attached to the positive electrode uncoated region 10a and the negative electrode uncoated region 11a, and the current collecting plate 30 and the second current collecting plate 31 are connected to external electrode terminals, and a current path is formed with a large cross-sectional area along the winding axis direction of the electrode assembly A (see arrow), which has the advantage of lowering the resistance of the battery cell. This is because resistance is inversely proportional to the cross-sectional area of ​​the path through which the current flows.

[0107] In one embodiment of the present specification, the positive electrode active material coated on the positive electrode plate and the negative electrode active material coated on the negative electrode plate may be any active material known in the art without limitation.

[0108] In one example, the positive electrode active material has the general chemical formula A[A x M y ]O 2+z (A includes at least one or more elements of Li, Na, and K; M includes at least one or more elements 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; the stoichiometric coefficients x, y, and z are selected such that the compound remains electrically neutral).

[0109] In another example, the positive electrode active material is an alkali metal compound xLiM as 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).

[0110] In still other examples, the positive electrode active material has 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 2contains at least one or more elements 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 a halogen group element selectively containing F; 0 < a ≤ 2, 0 ≤ x ≤ 1, 0 ≤ y < 1, 0 ≤ z < 1; the stoichiometric coefficients a, x, y, and z are selected so that the compound maintains electrical neutrality), or may be a lithium metal phosphate represented by Li3M2(PO4)3 [M contains at least one element selected from Ti, Si, Mn, Fe, Co, V, Cr, Mo, Ni, Al, Mg, and Al].

[0111] Preferably, the anode active material may include primary particles and / or secondary particles formed by aggregation of primary particles.

[0112] In one example, the cathode active material may use a carbon material, a lithium metal or a lithium metal compound, silicon or a silicon compound, tin or a tin compound, etc. Metal oxides such as TiO2 and SnO2 with a potential of less than 2V can also be used as the cathode active material. As the carbon material, either low-crystalline carbon and / or highly crystalline carbon may be used.

[0113] In one embodiment of the present specification, the separation membrane may be a porous polymer film, for example, a porous polymer film made of a polyolefin-based polymer such as a polyethylene homopolymer, a polypropylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, an ethylene / methacrylate copolymer, etc., used alone or laminated thereof. As another example, the separation membrane may use a normal porous non-woven fabric, for example, a non-woven fabric made of high melting point glass fibers, polyethylene terephthalate fibers, etc.

[0114] At least one surface of the separator may include a coating layer of inorganic particles. The separator itself may also be made of a coating layer of inorganic particles. The particles constituting the coating layer may have a structure in which they are bound to a binder such that there is an interstitial volume between adjacent particles.

[0115] The inorganic particles may be made of an inorganic material having a dielectric constant of 5 or more. As a non-limiting example, the inorganic particles may be Pb(Zr,Ti)O3 (PZT), Pb 1-x La x Zr 1-y Ti y O3(PLZT), PB(Mg3Nb 2 / 3 )O 3- It may contain at least one material selected from the group consisting of PbTiO3 (PMN-PT), BaTiO3, hafnia (HfO2), SrTiO3, TiO2, Al2O3, ZrO2, SnO2, CeO2, MgO, CaO, ZnO, and Y2O3.

[0116] The electrolyte is A + B - The salt may have the structure: + Li + , Na + , K + or combinations thereof. - 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:

[0117] The electrolyte may also 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 (ETM), gamma-butyrolactone, or a mixture thereof.

[0118] In one embodiment of the present specification, the uncoated portion of the first electrode and / or the second electrode may be bent from the outer periphery side of the electrode assembly toward the core side to form bent surfaces at the top and bottom of the electrode assembly. Also, the current collecting plate may be welded to the bent surface formed by bending the uncoated portion of the first electrode, and the second current collecting plate may be welded to the bent surface formed by bending the uncoated portion of the second electrode.

[0119] In order to relieve stress caused when the uncoated portion of the first electrode and / or the second electrode is folded, the first electrode and / or the second electrode may have a different structure. Figure 12 is a plan view showing an example of the structure of an electrode 90 according to an embodiment of the present invention.

[0120] Referring to FIG. 12, an electrode 90 includes a sheet-shaped current collector 91, an active material layer 92 formed on at least one surface of the current collector 91, and a plain portion 93 on a long edge of the current collector 91 where no active material is coated.

[0121] The plain portion 93 may include a plurality of segment pieces 93a that are notched. The plurality of segment pieces 93a may be formed into a plurality of groups, and the segment pieces 93a belonging to each group may have the same height (length in the Y direction) and / or width (length in the X direction) and / or spacing pitch. The number of segment pieces 93a belonging to each group may be increased or decreased from that shown in the figure. The segment pieces 93a may be trapezoidal, or may be modified into a rectangle, parallelogram, semicircle, or semi-ellipse. Preferably, the height of the segment pieces 93a may increase stepwise from the core side to the outer periphery side. Also, the core side plain portion 93' adjacent to the core side may not include a segment piece 93a, and the height of the core side plain portion 93' may be smaller than the areas of the other plain portions.

[0122] In one embodiment of the present specification, 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 further include an inorganic filler. The insulating coating layer 94 prevents an end of the active material layer 92 from contacting an active material layer of the opposite polarity facing the active material layer 92 via a separator, and serves to structurally support the folding of the segment pieces 93a. For this reason, when the electrode 90 is wound into an electrode assembly, it is preferable that at least a portion of the insulating coating layer 94 is exposed to the outside through the separator.

[0123] FIG. 13 is a cross-sectional view taken along a longitudinal direction Y of an electrode assembly A in which a segmented structure of the uncoated portion of an electrode 90 according to an embodiment of the present specification is applied to a first electrode and a second electrode.

[0124] 13, the uncoated portion 72 protruding downward extends from the first electrode, and the uncoated portion 73 protruding upward extends from the second electrode. The pattern in which the height of the uncoated portions 72, 73 varies is shown only diagrammatically. That is, the height of the uncoated portions 72, 73 may vary irregularly depending on the position where the cross section is cut. For example, when a side portion of a trapezoidal segment piece 93a is cut, the height of the uncoated portion in the cross section becomes lower than the height of the segment piece 93a. Therefore, it should be understood that the height of the uncoated portions 72, 73 shown in the cross section of the electrode assembly A corresponds to the average height of the uncoated portions included in each winding pattern.

[0125] The uncoated portions 72 and 73 may be folded from the outer periphery of the electrode assembly A to the core as shown in FIG. 14. In FIG. 13, the folded portion 101 is indicated by a dotted box. When the uncoated portions 72 and 73 are folded, the radially adjacent segments overlap each other to form a folded surface 102 at the top and bottom of the electrode assembly A. At this time, the uncoated portion on the core side (93' in FIG. 8) is too low to be folded, and the height h of the segment folded from the innermost side is equal to or smaller than the radial length r of the winding region formed by the uncoated portion 93' on the core side without a segment structure. Therefore, the cavity 80 in the core of the electrode assembly A is not closed by the folded segment. If the cavity 80 is not closed, the electrolyte injection process is not difficult and the electrolyte injection efficiency is improved.

[0126] In one embodiment of the present specification, the secondary battery may further include a battery can that houses the electrode assembly and has an opening; a sealing body that is configured to seal the opening of the battery can and includes a cap plate and a sealing gasket, and the terminal connection portion may be coupled to the connection plate.

[0127] FIG. 4 is a cross-sectional view of a secondary battery cut in the (Y) direction. As shown in FIG. 4, the cap plate is inserted into the inside of the battery cap, has a convex portion, one surface of the convex portion is exposed to the outside of the battery can, and the connecting plate is attached to the inner surface of the cap plate, for example, the surface facing the electrode assembly, excluding the inner surface of the convex portion.

[0128] The terminal connection portion of the inner current collector plate 30 of the battery can may be connected to the connection plate 42c.

[0129] The battery can 41 is made of a conductive metal material, but is not limited thereto.

[0130] 4, the sealing body 42 includes a cap plate 42a, a sealing gasket 42b, and a connecting plate 42c. The sealing gasket 42b encloses the edge of the cap plate 42a and is fixed by a crimping portion 43. The electrode assembly A is fixed in the battery can 41 by a beading portion 44 to prevent vertical movement.

[0131] The beading portion 44 prevents the electrode assembly A, which has a size corresponding to the width of the battery can 41, from slipping out of the upper opening of the battery can 41 and serves as a support on which the cap plate 42a is placed. Referring to FIG 4, the beading portion 44 refers to a recessed portion of the battery can.

[0132] The crimping portion 43 is formed on the beading portion 44. The crimping portion 43 has an extended and bent shape so as to enclose the outer circumferential surface of the cap plate 42a disposed on the beading portion 44 and a part of the upper surface of the cap plate 42a.

[0133] In the secondary battery of this specification, the positive electrode terminal is the cap plate 42a of the sealed body 42, and the negative electrode terminal is the battery can 41. The current collector 30 coupled to the uncoated portion 10a of the positive electrode plate 10 is electrically connected to a connection plate 42c attached to the cap plate 42a via a terminal connection portion. Also, the current collector 31 coupled to the uncoated portion 11a of the negative electrode plate 11 is electrically connected to the bottom of the battery can 41.

[0134] In one embodiment of the present specification, the insulator 46 is disposed between the upper end of the electrode assembly A and the beading portion 44, or between the current collecting plate 30 coupled to the upper portion of the electrode assembly A and the beading portion 44, and prevents contact between the terminal connecting portion 45 and the battery can 41, or between the current collecting plate 30 and the battery can 41. The insulator 46 has an insulator hole 47 through which the terminal connecting portion 45 can be pulled out. The terminal connecting portion is pulled out upward through the insulator hole 47 and coupled to the lower surface of the connection plate 42c or the lower surface of the cap plate 42a.

[0135] In this specification, the cap plate 42a may be made of a conductive metal material such as aluminum, steel, nickel, etc. Also, the sealing gasket 42b may be made of insulating and elastic polypropylene, polybutylene terephthalate, polyethylene fluoride, etc. However, the present invention is not limited by the materials of the cap plate 42a and the sealing gasket 42b.

[0136] In one embodiment of the present specification, the battery can 41 may further include a vent portion 41a formed on the bottom surface thereof. The vent portion 41a corresponds to a region of the bottom surface of the battery can 41 that is thinner than the surrounding region. The vent portion 41a is structurally weaker than the surrounding region. Therefore, when an abnormality occurs in the secondary battery and the internal pressure rises above a certain level, the vent portion 41a is broken to release the gas generated inside the battery can 41.

[0137] In one embodiment of the present specification, the secondary battery may further include a second current collecting plate 31 welded to the uncoated portion 11a of the second electrode. The second current collecting plate 31 is made of a conductive metal material such as aluminum, steel, or nickel.

[0138] The second current collector may be joined by welding on the inner bottom surface of the battery can. That is, one surface of the second current collector may be welded to the uncoated portion of the second electrode, and the other surface may be welded to the battery can, as in Fig. 11. The shape of the second current collector may be the same as the shape of the current collector described above, but is not limited to any shape commonly used in the industry without an additional electrode tab.

[0139] In one embodiment of the present specification, the secondary battery may be a cylindrical secondary battery having a form factor ratio (defined as the value obtained by dividing the diameter by the height of a cylindrical battery, i.e., the ratio of the diameter Φ to the height H) of greater than 0.4. Here, the form factor refers to a value indicating the diameter and height of a cylindrical secondary battery.

[0140] Conventionally, batteries with a form factor ratio of about 0.4 or less have been used. That is, conventionally, for example, 18650 cells, 21700 cells, etc. have been used. In the case of an 18650 cell, its diameter is about 18 mm, its height is about 65 mm, and its form factor ratio is about 0.277. In the case of a 21700 cell, its diameter is about 21 mm, its height is about 70 mm, and its form factor ratio is about 0.300.

[0141] A cylindrical secondary battery according to an embodiment of the present specification may be a 46110 cell, a 48750 cell, a 48110 cell, a 48800 cell, or a 46800 cell. In the number representing the form factor, the first two numbers represent the diameter of the cell, the next two numbers represent the height of the cell, and the last number 0 indicates that the cross section of the cell is circular.

[0142] The secondary battery according to one embodiment of the present specification may be a cylindrical secondary battery, which is a cylindrical cell having a diameter of 46 mm, a height of 110 mm, and a form factor ratio of 0.418.

[0143] The secondary battery according to one embodiment of the present specification may be a cylindrical secondary battery having a cylindrical cell with a diameter of 48 mm, a height of 75 mm, and a form factor ratio of 0.640.

[0144] The secondary battery according to one embodiment of the present specification may be a cylindrical secondary battery having a cylindrical cell with a diameter of 48 mm, a height of 110 mm, and a form factor ratio of 0.418.

[0145] The secondary battery according to one embodiment of the present specification may be a cylindrical secondary battery having a cylindrical cell with a diameter of 48 mm, a height of 80 mm, and a form factor ratio of 0.600.

[0146] The secondary battery according to one embodiment of the present specification may be a cylindrical secondary battery having a cylindrical cell with a diameter of 46 mm, a height of 80 mm, and a form factor ratio of 0.575.

[0147] The secondary battery according to an embodiment of the present specification may be used to manufacture a battery pack. Figure 15 is a diagram illustrating a schematic configuration of a battery pack according to an embodiment of the present invention.

[0148] 15, a battery pack 200 according to an embodiment of the present invention includes an assembly of electrically connected secondary battery cells 201 and a pack housing 202 that accommodates the assembly. The cylindrical secondary battery cells 201 are the battery cells according to the above-mentioned embodiment. For convenience of illustration, components such as a bus bar for electrically connecting the cylindrical battery cells 201, a cooling unit, and external terminals are omitted in the drawings.

[0149] The battery pack 200 may be mounted on a vehicle. The vehicle may be, for example, an electric vehicle, a hybrid vehicle, or a plug-in hybrid vehicle. The vehicle includes a four-wheeled vehicle or a two-wheeled vehicle. FIG. 16 is a diagram for explaining a vehicle including the battery pack 200 of FIG. 15.

[0150] 16, a vehicle V according to an embodiment of the present specification includes a battery pack 200 according to an embodiment of the present specification. The vehicle V is operated by receiving power from the battery pack 200 according to an embodiment of the present invention.

[0151] Although the present invention has been described above based on limited embodiments and drawings, the present invention is not limited thereto, and it is of course possible for a person having ordinary knowledge in the technical field to which the present invention pertains to make various modifications and variations within the technical spirit of the present invention and the equivalent scope of the claims described below. [Explanation of symbols]

[0152] A...electrode assembly 10...Anode plate 11 Cathode plate 10a: Uncoated portion of first electrode 11a: Uncoated portion of second electrode 12...Separation membrane 20, 91 Current collector 21, 92...active material 22, 93 Plain area 30 Current collector plate 30a...legs 30b: Welded part 30c Collector plate hole R1: Radius of the hole in the collector plate 31 Second current collecting plate 40...Secondary battery 41 Battery can 41a Vent section 42... Sealed body 42a Cap plate 42b Sealing gasket 42c...Connecting plate 43 Crimping section 44 Beading section 45...Terminal connection part 46 Insulator 47 Insulator hole 72 Plain area protruding from the bottom 73 Plain part protruding from the top 80...Cavity 90...electrode 93a...segmental piece 93' Plain area on core side 94 Insulating coating layer 101... Foldable part 102 .....Bending surface 200···Battery pack 201 Cylindrical secondary battery 202 Pack Housing V ···Automotive L: Outer diameter of secondary battery

Claims

1. An electrode assembly formed by stacking and winding a first electrode, a separator, and a second electrode, the first electrode including a first electrode current collector and an electrode active material layer provided on the first electrode current collector, and a long side end portion along the winding direction of the first electrode current collector is formed of a plain portion of the first electrode where the electrode active material layer is not provided; and a current collector provided at one end of the electrode assembly where the uncoated portion of the first electrode is exposed, the current collector including: a center portion corresponding to a winding core of the electrode assembly; and two or more legs each having one end connected to the center portion, extending in an outer periphery of the electrode assembly, and electrically connected to the uncoated portion of the first electrode, the center portion including a current collector hole; In a secondary battery in which an electrolyte is injected, the secondary battery comprising: A secondary battery, wherein the uncoated portion of the first electrode includes a plurality of notched segment pieces, the height of the segment pieces being formed so as to increase from the center of the electrode assembly toward the outer periphery, the segment pieces excluding the center of the electrode assembly are bent from the outer periphery of the electrode assembly toward the center and welded to the current collector plate, and the current collector plate hole in the center is not closed by the bent segment pieces.

2. The secondary battery according to claim 1 , wherein the two or more legs of the current collector plate are in a one-way shape, a cross shape, or a combination of a one-way shape and a cross shape.

3. The secondary battery according to claim 1 , wherein each of the two or more legs is welded to an uncoated portion of the first electrode and electrically connected thereto.

4. The secondary battery according to claim 1 , wherein the current collector plate has a thickness of 0.15 mm or more and 0.6 mm or less.

5. The secondary battery of claim 1 , wherein the current collector further comprises a terminal connector electrically connected to the center portion.

6. 6. The secondary battery according to claim 1, wherein the length of the legs is 25% to 50% of the outer diameter of the secondary battery as a reference.

7. 7. The secondary battery according to claim 1, wherein the width of the legs is 6% to 22% of the outer diameter of the secondary battery (100%).

8. 8. The secondary battery according to claim 1, wherein a ratio of an area of ​​a surface of the current collector facing the uncoated portion of the first electrode to an area of ​​a surface of the current collector that is in contact with the uncoated portion of the first electrode is 10% or more and 99% or less, based on an area of ​​100% of the surface of the current collector that faces the uncoated portion of the first electrode.

9. 8. The secondary battery according to claim 1, wherein a ratio of an area of ​​a surface of the uncoated portion of the first electrode that faces the current collector plate to an area of ​​the uncoated portion of the first electrode that contacts the current collector plate is 10% or more and 99% or less, based on an area of ​​100% of a surface of the uncoated portion of the first electrode that faces the current collector plate.

10. The secondary battery according to claim 1 , wherein the current collector plate has an aperture ratio defined by the following formula 1 of 20% or more and less than 100%: [Formula 1] Opening ratio (%) = 1 - (area of ​​the contact area between the current collector plate and the upper surface of the electrode assembly) / (area of ​​a circle whose diameter is the outer diameter of the electrode assembly) = (area where the current collecting plate is not in contact with the upper surface of the electrode assembly) / (area of ​​a circle whose diameter is the outer diameter of the electrode assembly).

11. The secondary battery according to claim 5 , wherein the terminal connector is bent one or more times toward the center of the current collector plate.

12. The secondary battery according to claim 5 or 11, wherein the terminal connector is provided between two adjacent legs.

13. 13. The secondary battery according to claim 5, wherein a thickness of a connection portion between the terminal connection portion and the current collector plate is the same as a thickness of the current collector plate.

14. 14. The secondary battery according to claim 5, wherein the length of the terminal connection portion is 20 mm or more and 40 mm or less.

15. 15. The secondary battery according to claim 5, wherein the width of the terminal connection portion is 8% to 35% of the outer diameter of the secondary battery (100%).

16. The secondary battery further includes a battery can that houses the electrode assembly and has an opening; a sealing body that is configured to seal the opening of the battery can and includes a cap plate and a sealing gasket; The secondary battery according to claim 5 , wherein the terminal connector is directly connected to the cap plate or is coupled to a connector plate attached to the cap plate.

17. A battery pack comprising a plurality of the secondary batteries according to claim 1 .

18. 20. A motor vehicle including at least one battery pack according to claim 17.

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