CID filter, and secondary battery, battery module, and battery pack comprising same

Abstract

The present invention relates to a CID filter for a secondary battery, the CID filter comprising: a central portion located at the center of the CID filter; a peripheral portion located at the edge of the CID filter; and an intermediate portion including at least one through-hole located along the circumference of the central portion and a CID bridge connecting the central portion and the peripheral portion, wherein the through-hole is asymmetrically located with respect to any one line passing through the central point of the CID filter.

Description

CID filter and secondary battery, battery module and battery pack including the same

[0001] This application is based on Korean Patent Application No. 10-2024-0194830, which was filed with the Korean Intellectual Property Office on December 24, 2024, and whose contents are incorporated herein by reference in whole, and claims priority thereof.

[0002] The present invention relates to a CID filter, a secondary battery including the same, a battery module including the same, a battery pack including the same, and an automobile.

[0003] Unlike primary batteries, which cannot be recharged, secondary batteries refer to batteries that can be charged and discharged, and these secondary batteries are widely used in the field of advanced electronic devices such as phones, laptop computers, and camcorders.

[0004] Secondary batteries can ensure stability by undergoing a stability test that measures internal short circuits by compressing one side with a press.

[0005] Secondary batteries are classified according to the shape of the battery case into cylindrical and prismatic batteries, in which the electrode assembly is embedded in a cylindrical or prismatic metal battery case, and pouch-type batteries, in which the electrode assembly is embedded in a pouch-type battery case made of an aluminum laminate sheet.

[0006] Meanwhile, there are cases where the temperature or internal pressure of a secondary battery rises due to abnormal behavior of the secondary battery; to prevent or suppress the risk of fire or explosion that may occur in such cases, safety devices are provided within the secondary battery.

[0007] The present invention aims to provide a CID (Current Interruptive Device) filter capable of smoothly and quickly discharging gas generated inside a secondary battery to the outside during operations such as overheating, short circuit, or fire, and a secondary battery, battery module, and battery pack including the same.

[0008] One embodiment of the present invention provides a CID (Current Interruptive Device) filter for a secondary battery, comprising: a central portion located at the center of the CID filter; a peripheral portion located at the edge of the CID filter; and an intermediate portion including at least one through hole located along the circumference of the central portion and a CID bridge connecting the central portion and the peripheral portion, wherein the through hole is positioned asymmetrically with respect to any one line passing through the center point of the CID filter.

[0009] One embodiment of the present invention provides a secondary battery comprising: an electrode assembly including an electrode and a separator; a battery case that accommodates the electrode assembly and has an open top; a top cap coupled to the top of the battery can; a safety vent provided at the bottom of the top cap; and a CID filter for a secondary battery according to claim 1, provided at the bottom of the safety vent, wherein at least a portion of the upper surface is located on the lower surface of the safety vent.

[0010] A secondary battery including a CID filter according to an embodiment of the present invention, a battery module including the same, and a battery pack can prevent the explosion of the secondary battery by smoothly and quickly discharging gas generated inside the secondary battery to the outside through the adjustment of the size and position of the gas discharge hole of the CID filter.

[0011] The following drawings attached to this specification illustrate embodiments of the present invention and serve to further enhance understanding of the technical concept of the present invention together with the detailed description of the invention provided below; therefore, the present invention should not be interpreted as being limited only to the matters described in such drawings.

[0012] FIG. 1 is a plan view illustrating a CID filter according to one embodiment of the present invention.

[0013] FIG. 2 is a projection view of a cylindrical secondary battery showing the coupling position of an electrode tab according to one embodiment of the present invention.

[0014] FIG. 3 is a cross-sectional view illustrating a secondary battery according to one embodiment of the present invention.

[0015] FIG. 4 is a perspective view illustrating a battery pack including a secondary battery according to one embodiment of the present invention.

[0016] FIG. 5 is a perspective view illustrating a means of transport including a battery pack according to one embodiment of the present invention.

[0017] Figure 6 is a graph measuring the flow rate of gas discharged through the through-hole of the CID filter over time in a secondary battery according to Example 1 and Comparative Example 1.

[0018] Figure 7 is a photograph showing the gas discharge flow in which internal gas of a secondary battery according to Example 1 and Comparative Example 1 is discharged to the outside through the through hole of a CID filter.

[0019] Figure 8 is a photograph showing the pressure difference between the discharge hole of the top cap (hereinafter, upper part of the positive tab, ①) through which gas is discharged to the outside in the secondary battery according to Example 1 and Comparative Example 1, and the space between the positive tab and the electrode assembly (hereinafter, lower part of the positive tab, ②).

[0020] FIG. 9(a) is a perspective view illustrating a secondary battery according to Comparative Example 2, and FIG. 9(b) is a perspective view illustrating a secondary battery according to Example 2.

[0021] FIG. 10 is a graph showing the internal pressure of the secondary battery of Example 2 and Comparative Example 2 over time.

[0022] In parts of the attached drawings, corresponding components are given the same reference numerals. Those skilled in the art understand that the drawings are intended to illustrate elements simply and clearly and are not necessarily drawn to scale. For example, to aid in understanding various embodiments, the dimensions of some elements depicted in the drawings may be exaggerated compared to others. Additionally, elements of known technology that are useful or essential in commercially viable embodiments may often be omitted so as not to hinder the spirit of the various embodiments of the present invention.

[0023] [Explanation of the symbol]

[0024] 1: Secondary battery

[0025] 2: Pack Housing

[0026] 3: Battery pack

[0027] 100: Electrode assembly

[0028] 200: Battery case

[0029] 210: Bidding Department

[0030] 220: Creaming Department

[0031] 300: Cap Assembly

[0032] 310: Top Cap

[0033] 320: Safety vent

[0034] 330: CID Filter

[0035] 331: Center

[0036] 332: Periphery

[0037] 333: Through hole

[0038] 333a: Main through hole

[0039] 333b: Auxiliary through-hole

[0040] 334: CID Bridge

[0041] 340: Sealing gasket

[0042] 350: CID gasket

[0043] 400: Insulator

[0044] 410: Tab hole

[0045] T: Electrode tab

[0046] V: Means of transportation

[0047] C: China

[0048] W: Length of the through hole

[0049] E1: 1st end

[0050] E2: Second end

[0051] L1: Line connecting the first end

[0052] L2: Line connecting the second end

[0053] The detailed description of the present invention is intended to explain the invention to those skilled in the art. Throughout the specification, when a part is described as "comprising" a certain component or "featuring" a certain structure and shape, unless specifically stated otherwise, this does not mean that other components are excluded or other structures and shapes are excluded, but rather that other components, structures, and shapes may be included.

[0054] The present invention is capable of various modifications and may have various embodiments, and specific embodiments are presented and described in detail in the detailed description. However, this is not intended to limit the scope of the invention with respect to the embodiments, and it should be understood that it includes all modifications, equivalents, and substitutions that fall within the spirit and scope of the invention.

[0055] As used herein, “about,” “approximately,” and “substantially” are used to mean a range of values ​​or degrees or approximations thereof, taking into account inherent manufacturing and material tolerances (e.g., ±5%).

[0056] As a safety device provided in a secondary battery, a safety vent, which is mainly installed in cylindrical secondary batteries, can be cited. For example, when the internal pressure of the secondary battery rises, the safety vent moves upward and a portion of the vent ruptures, forming a path for gas discharge. By allowing gas inside the secondary battery to be discharged to the outside through this path, the risk of explosion can be prevented or suppressed.

[0057] Another example is the CID (Current Interruptive Device) filter, which is primarily installed in cylindrical secondary batteries. The CID filter is positioned below the safety vent and has a structure attached to the safety vent; as the aforementioned safety vent moves upward, the CID filter also moves upward with it, and the flow of current can be interrupted as a portion of the CID filter breaks.

[0058] However, if gas discharge through the CID filter is not smooth, a problem arises where the secondary battery undergoes thermal runaway and explodes. The present invention provides a technology that can prevent or suppress the explosion of a secondary battery by smoothly and rapidly discharging gas generated inside the secondary battery to the outside through the adjustment of the size and location of the gas discharge holes of the CID filter.

[0059] FIG. 1 is a plan view illustrating a CID filter (330) of a cylindrical secondary battery according to one embodiment of the present invention, FIG. 2 is a projection view of a cylindrical secondary battery illustrating the coupling position of an electrode tab (T) according to one embodiment of the present invention, and FIG. 3 is a cross-sectional view illustrating a cylindrical secondary battery (1) according to one embodiment of the present invention.

[0060] A cylindrical secondary battery (1) according to the present invention comprises an electrode assembly (100), a battery case (200), and a cap assembly (300), and the cap assembly (300) comprises a top cap (310), a safety vent (320), and a CID filter (330).

[0061] The top cap (310) is located at the uppermost part of the cap assembly (300) and may protrude in the opposite direction to the center of the battery case (200) or the internal direction of the battery case (200). The top cap (310) may serve as an electrode terminal of the secondary battery (1) so that the protruding part is electrically connected to the outside, and for example, the top cap (310) may serve as a positive terminal of the secondary battery (1).

[0062] A sealing gasket (340) may be attached to the edge of the top cap (310), and the sealing gasket (340) may be located inside the crimping portion (220) of the battery case (200). The sealing gasket (340) can increase the sealing force between the top cap (310) and the battery case (200).

[0063] The top cap (310) may include a protrusion protruding upward, a rim portion that contacts and is coupled with a sealing gasket (340), and a first connecting portion that connects the protrusion and the rim portion. The first connecting portion may include at least one gas discharge hole.

[0064] The safety vent (320) is located at the bottom of the top cap (310) and can be electrically connected to the top cap (310). At least a portion of the surface of the safety vent (320) facing the top cap (310) may be in contact with the top cap (310). The safety vent (320) may be in contact with the top cap (310) for a certain length from the end, and the portion excluding the contact length may be positioned at a certain distance from the top cap (310). Additionally, the portion of the safety vent (320) that is in contact with the top cap (310) may be combined with a sealing gasket (340).

[0065] The distance between the safety vent (320) and the top cap (310) can increase as it moves toward the center of the safety vent (320) in the area where it contacts the top cap (310).

[0066] The safety vent (320) may include a contact portion that contacts the top cap (310), a central portion located at the center of the safety vent (320) and in contact with the CID filter and recessed in the direction in which the electrode assembly (100) is located, and a second connecting portion connecting the contact portion and the central portion. Additionally, the safety vent (320) may be provided with a bend (or notch) at the portion where the contact portion and the second connecting portion, and the second connecting portion and the central portion, contact each other.

[0067] In one embodiment, the safety vent (320) may be provided with an end portion perpendicular to the axial direction of the battery case (200). The top cap (310) may be provided perpendicular to the axial direction of the battery case (200) in the same manner as the safety vent (320). For example, the safety vent (320) and the top cap (310) may be positioned horizontally.

[0068] In another embodiment, the safety vent (320) may be provided in a form where the end portion is bent to wrap around the outer surface of the top cap (310).

[0069] The safety vent (320) includes a contact portion and a second connecting portion, and a first breaking portion at the portion where the second connecting portion and the central portion come into contact, and the first breaking portion may include at least one notch and may be provided in a certain shape.

[0070] When an electrolyte decomposition reaction and thermal runaway phenomenon occur due to heat generation caused by internal short circuit, overcharging, over-discharging, etc., gas is generated or heat is generated inside the secondary battery (1), causing the internal pressure to rise. When the pressure inside the secondary battery (1) rises, the safety vent (320) receives force in the direction of the top cap (310), and the first rupture part ruptures, causing the gas inside the secondary battery (1) to be discharged.

[0071] The first fracture section may include both ends, and the two ends may be spaced apart by a certain distance. The notch of the first fracture section may be formed in a certain shape so that the two ends of the first fracture section can be connected. For example, the first fracture section may be formed in at least one shape among a curve and a straight line, such as a U-shape or a V-shape. And, the area between the two ends is a non-fracturing section that is not fractured by the internal pressure of the secondary battery (1).

[0072] The notch of the first break portion may be provided on one of the two sides of the safety vent (320), for example, the notch of the first break portion may be provided on the opposite side of the two sides of the safety vent (320) facing the electrode assembly (100).

[0073] The CID filter (330) is located at the bottom of the safety vent (320), and at least a portion of it can be connected to the safety vent (320).

[0074] The CID filter (330) may include a central portion connected to a safety vent (320) in the central portion and a central portion (331) protruding in the direction where the safety vent (320) is located, a peripheral portion (332) excluding the central portion (331), a CID bridge (334) connecting the central portion (331) and the peripheral portion (332), and a middle portion including a through hole (333) for discharging gas generated inside the secondary battery (1) to the outside.

[0075] At this time, the middle portion may be divided into an area in which a through hole (333) is formed. For example, the through hole (333) may include a first end located in the direction of the center of the CID filter (330) (or the direction in which the center (331) is located) and a second end located in the direction of the edge of the CID filter (330) (or the direction in which the peripheral portion (332) is located).

[0076] In one embodiment, when a through hole (333) is included in the middle section, the middle section may be divided into an extension line (L1) extending the first end (E1) in a clockwise or counterclockwise direction and an extension line (L2) extending the second end (E2) in a clockwise or counterclockwise direction.

[0077] In another embodiment, when a plurality of through holes (333) are included in the middle section, the center (331), the periphery (332), and the middle section may be areas partitioned by a line (L1) connecting the first end (E1) of the plurality of through holes (333) and a line (L2) connecting the second end (E2) of the plurality of through holes (333).

[0078] At this time, the end of the through hole (333) dividing the middle section can be based on the widest through hole (333), and the length of the through hole (333) refers to the distance between the first end (E1) and the second end (E2).

[0079] The CID filter (330) is separated from the safety vent (320) and cuts off the current when the safety vent (320) ruptures as the internal pressure of the secondary battery (1) increases.

[0080] When the safety vent (320) is deformed in the direction in which the top cap (310) is located, the CID bridge (334) is broken so that the center (331) can be separated from the periphery (332). For example, the center (331) is separated in the direction of the top cap (310) while remaining connected to the safety vent (320).

[0081] The through hole (333) may include a main through hole (333a) and an auxiliary through hole (333b), and one or more main through hole (333a) and auxiliary through hole (333b) may be included. For example, the center may include one main through hole (333a) and multiple auxiliary through holes (333b).

[0082] At least one of the length and area of ​​the main through hole (333a) and the auxiliary through hole (333b) may differ from that of the through hole (333). The length of the main through hole (333a) may be longer than the length of the auxiliary through hole (333b), the area or width of the main through hole (333a) may be wider than the area or width of the auxiliary through hole (333b), or the length and area of ​​the main through hole (333a) may be longer and wider than the length and area of ​​the auxiliary through hole (333b).

[0083] The through hole (333) is not specifically limited in shape as long as it can discharge internal gas of the secondary battery (1) to the outside, but according to one embodiment, the plurality of through holes (333) may include at least one shape among a circular, square, and arc shape, or at least one shape among a circular and arc shape.

[0084] The length of the through hole (333) refers to the length of an arc passing through the center of the through hole (333). In other words, the length of the through hole (333) refers to a straight line or curve passing through the center of the through hole (333), or the length of a straight line or curve connecting the center of the through hole (333) and two points on the perimeter of the through hole (333). At this time, the two points on the perimeter of the through hole (333) are symmetrically positioned and refer to the point located furthest away from the center.

[0085] The length of the main through hole (333a) may be approximately 30% to 70% of the circumference of the circle connecting the centers of the main through hole (333a) and the auxiliary through hole (333b), that is, the circumference of the intermediate circle passing through the centers of the main through hole (333a) and the auxiliary through hole (333b). For example, the length of the main through hole (333a) may be approximately 35% to 65% of the circumference of the circle connecting the centers of the main through hole (333a) and the auxiliary through hole (333b), or approximately 40% to 60%.

[0086] According to one embodiment, the width (or area) of the main through hole (333a) may be formed in about 3 / 10 to 7 / 10 of the total area of ​​the center. For example, the width of the main through hole (333a) may be formed in about 7 / 20 to 13 / 20, or in about 2 / 5 to 3 / 5.

[0087] By satisfying the above range for the length and width of the main through hole (333a), the area through which the high-pressure gas inside the secondary battery (1) is discharged to the outside is wide, thereby lowering the discharge pressure and allowing the high-pressure gas to be discharged smoothly and quickly to the outside.

[0088] The CID bridge (334) is formed by a plurality of through holes (333) being spaced apart from each other, and the length or width of the CID bridge (334) can be adjusted according to the spacing of the through holes (333). The length or width of the CID bridge (334) refers to the distance between the first end (E1) and the second end (E2) of two points at corresponding or symmetrical positions of two adjacent through holes (333).

[0089] The intermediate section according to the present invention includes a plurality of auxiliary through holes (333b) and one main through hole (333a), and the length of the CID bridge (334) located between the auxiliary through holes (333b) may be longer than the length of the CID bridge (334) located between the main through hole (333a) and the auxiliary through hole (333b).

[0090] When multiple CID bridges (334) are included between auxiliary through holes (333b) in the middle section, the lengths of the multiple CID bridges (334) may all be the same, or at least one may have a different length.

[0091] For example, among the multiple CID bridges (334), the length of the CID bridge (334) facing the main through hole (333a) may be the longest.

[0092] An electrode tab (T) described later may be coupled to one of the multiple CID bridges (334). The length of the CID bridge (334) to which the electrode tab (T) is coupled may be equal to the width of the electrode tab (T) or wider than the width of the electrode tab (T). The electrode tab (T) coupled to the CID bridge (334) may be a negative electrode tab or a positive electrode tab, and for example, may be a positive electrode tab.

[0093] The electrode tab (T) can be coupled to a CID bridge (334) located between adjacent auxiliary through holes (333b). According to one embodiment, the electrode tab (T) can be coupled to a CID bridge (334) facing the main through hole (333a).

[0094] For example, the electrode tab (T) can be coupled with the longest CID bridge (334) among the plurality of CID bridges (334). Also, the electrode tab (T) can be coupled with the CID bridge (334) located furthest from the main through hole (333a).

[0095] As long as the electrode tab (T) and the CID bridge (334) can be electrically connected, the method of joining is not particularly limited, but for example, the electrode tab (T) can be joined to the CID bridge (334) by welding.

[0096] By connecting the electrode tab (T) to the CID bridge (334) at a position opposite the main through hole (333a), the electrode tab (T) does not block part or all of the main through hole (333a), so that the internal gas of the secondary battery (1) can be easily discharged to the outside through the main through hole (333a).

[0097] As the length of the CID bridge (334) is equal to or wider than the length of the electrode tab (T), the electrode tab (T) does not block part or all of the auxiliary through hole (333b), so that the path for gas inside the secondary battery (1) to be discharged to the outside is not reduced, and gas that could not be discharged to the outside through the main through hole (333a) is quickly discharged to the outside through the auxiliary through hole (333b), thereby preventing the explosion of the secondary battery (1).

[0098] The cap assembly (300) according to the present invention may further include a CID gasket (350). The CID gasket (350) wraps around the edge of the CID filter (330) and can electrically isolate the peripheral portion (332) and the middle portion of the CID filter (330) from the safety vent (320).

[0099] A secondary battery (1) according to another embodiment of the present invention may further include an insulator (400) between the electrode assembly (100) and the CID filter (330).

[0100] The insulator (400) may be positioned to cover the upper surface of the electrode assembly (100). By the insulator (400) covering the upper surface of the electrode assembly (100), direct contact between the electrode assembly (100) and the cap assembly (300) can be prevented or suppressed.

[0101] The insulator (400) may include a tab hole (410) so that an electrode tab protruding upward from the electrode assembly (100) can be drawn out. The electrode tab can be drawn out upward through the tab hole (410) and coupled to the CID bridge (334).

[0102] The tap hole (410) may discharge gas generated inside the secondary battery (1) to reduce the internal pressure of the secondary battery (1).

[0103] The insulator (400) may include a plurality of tap holes (410), and any one of the plurality of tap holes (410) may be positioned such that its center corresponds to the center of the through hole (333) of the CID filter. For example, any one of the plurality of tap holes (410) may be positioned such that its center corresponds to the center of the main through hole (333a) of the CID filter.

[0104] The insulator (400) may be made of an insulating polymer resin, such as polyethylene, polypropylene, polyimide, or polybutylene terephthalate.

[0105] The secondary battery (1) may further include a current collector plate (not shown) between the insulator (400) and the electrode assembly (100).

[0106] One side of the battery case (200) is open, and a space for accommodating an electrode assembly (100) and an electrolyte may be provided inside.

[0107] The electrolyte may be a non-aqueous organic solvent. The non-aqueous organic solvent may include, for example, a cyclic carbonate-based solvent, a linear carbonate-based solvent, or a mixture thereof. The non-aqueous organic solvent may include, for example, one or more substances selected from ethylene carbonate, dimethyl carbonate, and ethylmethyl carbonate.

[0108] According to one embodiment, the battery case (200) may be provided with a columnar structure having a space formed inside. The battery case (200) may accommodate an electrode assembly (100) including an electrode and a separator and an electrolyte in the internal space. The battery case (200) may have a structure in which one side is open (hereinafter referred to as an opening) and the other side is sealed. Here, the one side and the other side of the battery case (200) refer to ends located at the top and bottom along the direction of gravity or the central axis of the battery case (200), and the one surface and the other surface refer to cross-sections located at the top and bottom along the central axis of the battery case (200).

[0109] According to one embodiment, the battery case (200) may be made of a lightweight conductive metal material such as aluminum or an aluminum alloy.

[0110] According to one embodiment, the battery case (200) may be provided with a beading portion (210) and a crimping portion (220) to secure the cap assembly (300). For example, the battery case (200) may have the crimping portion (220) and the beading portion (210) positioned sequentially from the opening toward the lower side of the battery case (200).

[0111] The beading portion (210) may be positioned between the upper surface of the electrode assembly (100) and the opening, or between the upper surface of the electrode assembly (100) and the crimping portion (220), in a form where the side of the battery case (200) is folded toward the center of the battery case (200). A cap assembly (300) may be positioned on one side of the beading portion (210).

[0112] Here, the side of the battery case (200) refers to the side connecting one side and the other side.

[0113] An electrode assembly (100) according to one embodiment comprises a positive electrode, a negative electrode, and one or two separators and is a power generation device capable of charging and discharging.

[0114] For example, the electrode assembly (100) may include a first separator, a cathode, a second separator, and an anode stacked in order, or a jelly roll structure supplied to a winding core and wound. Alternatively, the electrode assembly (100) may include a cathode, a first separator, an anode, and a second separator stacked in order, or a jelly roll structure supplied to a winding core and wound.

[0115] According to one embodiment, the electrode assembly (100) may include a hollow (C) located on the winding axis of the electrode assembly (100). The hollow (C) may be formed by winding an anode, a cathode, and a separator onto a winding core and then removing the winding core. The electrode assembly (100) may have a hollow (C) that is empty, or a center pin may be accommodated in the hollow (C).

[0116] The center pin can prevent or suppress the deformation or collapse of the shape of the core portion due to the expansion and contraction of the electrode assembly (100). The core portion may refer to a hollow (C) or a region including a hollow (C) and a portion of the wound cathode, first separator, anode, and second separator adjacent to the hollow (C).

[0117] For example, the core portion may refer to an area within 2 turns of the electrode from one end in the longitudinal direction of the electrode located at the innermost angle of the electrode assembly (100). Additionally, '1 turn' may refer to the length required for 360° winding from a reference point of the electrode or separator included in the electrode assembly (100), and the length may be determined according to the outer diameter of the winding core used for winding the electrode assembly (100), the thickness of the electrode or separator, and the number of turns of the electrode or separator located inside. For example, 1 turn of the negative electrode may refer to the length required to wind the negative electrode 360° from the longitudinal end of the negative electrode in the direction in which the jellyroll-type electrode assembly is wound.

[0118] The positive electrode may include a positive active material portion and a positive non-positive portion. For example, the positive electrode is a positive active material coated on one or more of the two sides of a positive current collector, wherein the area coated with the positive active material is the positive active material portion and the area not coated with the positive active material is the positive non-positive portion.

[0119] The anode-free portion is the part where the anode current collector is exposed to the outside, and the anode-free portion and the anode current collector may be made of the same material. For example, the anode current collector and the anode-free portion may be made of a metal foil with excellent conductivity, and for example, the anode current collector and the anode-free portion may include aluminum (Al) foil.

[0120] The positive electrode blank portion is not coated with positive electrode active material, so that the first electrode tab is located therein, allowing the positive electrode to be electrically connected to the cap assembly (300) described later. For example, the first electrode tab can be joined to the positive electrode blank portion through welding.

[0121] The cathode active material may include lithium cobalt oxide, which has a high operating voltage and excellent capacity characteristics; lithium nickel oxide, which has a high reversible capacity and facilitates the implementation of a large-capacity battery; lithium nickel cobalt oxide, in which part of the nickel is substituted with cobalt; lithium nickel cobalt metal oxide, in which part of the nickel is substituted with manganese, cobalt, or aluminum; lithium manganese-based oxide, which has excellent thermal stability and is inexpensive; and lithium iron phosphate, which has excellent stability.

[0122] The cathode may include a cathode active material portion and a cathode non-active portion. For example, the cathode is formed by coating a cathode active material on one or both sides of a cathode current collector, wherein the cathode active material portion is formed by coating or applying the cathode active material, and the cathode non-active portion is an area where the cathode current collector is exposed without coating or applying the cathode active material. For example, the cathode current collector and the cathode non-active portion may include a thin metal plate with excellent conductivity, namely, a copper (Cu) or nickel (Ni) foil.

[0123] The negative electrode blank portion is not coated with a negative electrode active material, so the second electrode tab is located therein, allowing the negative electrode to be electrically connected to the case (200) described later. For example, the second electrode tab and the negative electrode blank portion can be joined by welding the second electrode tab to the negative electrode blank portion.

[0124] The cathode may further include a third electrode tab. In one embodiment, the cathode may have a cathode non-negative portion located on both sides of the cathode active material portion. In other words, the cathode may be positioned in the order of a cathode non-negative portion, a cathode active material portion, and a cathode non-negative portion from the winding start end of the cathode current collector towards the winding end end.

[0125] According to one embodiment, an electrode tab may be positioned on each of the negative electrode uncoated portions located at the negative electrode winding start end and the winding end end. For example, a second electrode tab may be attached to the negative electrode uncoated portion located at the negative electrode winding start end, and a third electrode tab may be attached to the negative electrode uncoated portion located at the negative electrode winding end end.

[0126] The negative electrode active material may be, for example, carbon materials such as crystalline carbon, amorphous carbon, carbon composites, and carbon fibers, lithium metal, or lithium alloy. For high-capacity design, the negative electrode active material may further include, for example, non-graphite-based SiO2 (silica) or SiC (silicon carbide).

[0127] The first electrode tab and the second electrode tab can protrude in opposite directions relative to the electrode assembly of the jellyroll structure to transfer electrons collected in the current collector to an external circuit.

[0128] The separator prevents internal short circuits that may occur when the anode and cathode come into contact, and may include a porous material to facilitate the movement of ions between the electrodes.

[0129] In one embodiment, the separator may include a substrate layer made of a porous material. The substrate layer may include, for example, any one selected from polyethylene (PE), polystyrene (PS), polypropylene (PP), and a copolymer of polyethylene (PE) and polypropylene (PP).

[0130] In another embodiment, the separator may include a Safety Reinforced Separator (SRS) membrane. For example, the separator may include a substrate layer made of a porous material and a coating layer formed by applying a mixed slurry, which is a mixture of inorganic particles and a binder polymer, coated on the substrate layer. The coating layer has a uniform pore structure formed by the interstitial volume between the ceramic particles, which are active layer components, along with the pore structure contained in the separator substrate itself, including ceramic particles.

[0131] The coating layer may comprise ceramic particles comprising at least one selected from alumina, silica, TiO2, SiC, and MgAl2O4. By including such a coating layer, the safety of the electrode assembly can be enhanced. According to one embodiment, the coating layer may further comprise a lithium salt.

[0132] According to one embodiment of the present invention, a battery pack (3) comprising any one of the secondary batteries (1) described above is provided.

[0133] In relation to the above embodiment, referring to FIG. 4, a battery pack (3) containing a secondary battery (1) in a pack housing (2) is shown.

[0134] The battery pack (3) according to the above embodiment has high output / high capacity.

[0135] According to one embodiment of the present invention, a means of transportation including the battery pack (3) described above is provided.

[0136] With reference to FIG. 5 in relation to the above embodiment, a means of transportation (V) including a battery pack (3) is illustrated. According to one embodiment, the means of transportation (V) may be an electric vehicle.

[0137] The means of transportation according to the above embodiment uses a battery pack (3) having high output / high capacity, so it is excellent in terms of stability and safety.

[0138]

[0139] Electrode Assembly Manufacturing

[0140] An Al foil with a thickness of 15 μm and a width of 63.9 mm was prepared as a positive current collector, and a positive active material slurry containing an NMCA (Ni-Mn-Co-Al) composite with a Ni content of 92% or more as a positive active material and CNT as a conductive material was applied and dried on the positive current collector to form a positive active material layer, thereby manufacturing a positive electrode having a thickness of 154 μm.

[0141] The positive electrode includes a positive electrode uncoated portion where the positive electrode active material slurry is not coated and a positive electrode active material portion coated with the positive electrode active material slurry, and is positioned in the order of the positive electrode uncoated portion, the positive electrode active material portion, and the positive electrode uncoated portion. Additionally, a positive electrode tab is coupled to each positive electrode uncoated portion.

[0142] Next, a Cu foil with a thickness of 8 μm and a widthwise length of 65.1 mm was prepared as a cathode current collector, and a cathode active material slurry containing 50 parts by weight each of artificial graphite and natural graphite as cathode active materials was applied to the cathode current collector and dried to form a cathode active material layer, thereby manufacturing a cathode having a thickness of 187 μm.

[0143] The cathode includes a cathode-free section where the cathode active material slurry is not applied and a cathode active material section where the cathode active material slurry is applied, and is positioned in the order of the cathode active material section, the cathode-free section, and the cathode active material section. And, a cathode tab is coupled to the cathode-free section.

[0144] Two separators were prepared, each having a coating layer formed on one side of a sheet-type polyethylene substrate layer, comprising Al2O3 as an inorganic component, a PVdF-based binder, and a lithium salt as a binder component, as a first separator and a second separator.

[0145] A jelly-roll type electrode assembly was manufactured by stacking a first separator, a cathode, a second separator, and an anode in sequence and then winding them.

[0146]

[0147] Manufacturing of secondary batteries

[0148] After inserting the above jelly-roll type electrode assembly into a cylindrical battery case, an electrolyte solution was injected by mixing ethylene carbonate (EC):dimethyl carbonate (DMC):ethyl methyl carbonate (EMC) in a weight ratio of 4:9:3 and dissolving LiPF6 to contain 15 wt%, and the cylindrical battery case was sealed with a cap assembly to manufacture a secondary battery.

[0149] Example 1

[0150] In the secondary battery according to Example 1, the positive tap (in tap) located at the winding start portion of the positive non-positive portion is connected by extending to the center from the bridge of the CID filter of the cap assembly.

[0151] Example 2

[0152] The secondary battery according to Example 2 is the secondary battery of Example 1 with an additional insulator, wherein the insulator is positioned between the electrode assembly and the CID filter and includes two tab holes. The center of one of the two tab holes is positioned at a location corresponding to the center of the main through-hole of the CID filter, and the positive tab is drawn out from the other tab hole.

[0153] Comparative Example 1

[0154] In the secondary battery according to Comparative Example 1, the positive tap (in tap) located at the winding start portion of the positive non-positive portion is coupled to the center by crossing one of the through holes of the CID filter.

[0155] Comparative Example 2

[0156] The secondary battery according to Comparative Example 2 is the secondary battery of Example 1 with an additional insulator, wherein the insulator is positioned between the electrode assembly and the CID filter and includes one tab hole.

[0157] Measurement of internal pressure and exhaust gas flow rate of secondary batteries

[0158] The temperature of the atmosphere where the secondary battery is located is 23℃ and the pressure is 1 bar, and the internal temperature of the secondary battery is 750℃ and the pressure is 10 bar.

[0159] The internal pressure was measured at the core of the electrode assembly, and the exhaust gas flow rate was measured at the gas discharge hole of the top cap located facing the anode tab in the example, and at the gas discharge hole of the top cap located at a position corresponding to the anode tab in the comparative example.

[0160] Figure 6 is a graph measuring the flow rate of gas discharged through the through-hole of the CID filter over time in a secondary battery according to Example 1 and Comparative Example 1.

[0161] In Example 1 and Comparative Example 1, assuming gas movement between a cell of the same volume (e.g., the same amount of gas) and the external atmosphere, since the cross-sectional area of ​​the passage between the cell and the external atmosphere in Example 1 is wider, it can be confirmed that the gas flow velocity in the through hole is up to about 200 m / s slower in Example 1 than in Comparative Example 1, based on the point immediately after 0.0003 seconds have passed.

[0162] In the case of Comparative Example 1, the flow rate in the gas discharge hole of the top cap is slower than in the example, so the time it takes for the internal pressure of the secondary battery to decrease is longer than in Example 1, and therefore, Comparative Example 1 has a problem in that the pressure discharge is not smooth and there is a high possibility of an explosion.

[0163] And, Fig. 7 is a photograph showing the gas discharge flow in which the internal gas of the secondary battery according to Example 1 and Comparative Example 1 is discharged to the outside through the through hole of the CID filter.

[0164] Referring to FIG. 7, in Comparative Example 1, the gas is not discharged smoothly through the through hole of the CID filter in the part where the positive tab is located, so it is discharged through the through hole of the CID filter facing the positive tab. And, it can be seen that the gas flows through the space between the safety vent and the CID filter (①) and is discharged through the gas discharge hole (③) of the top cap at a position corresponding to the part where the positive tab is located.

[0165] In Example 1, the length of the through hole of the CID filter facing the anode tab is the widest, and the gas is discharged through the through hole facing the anode tab. Also, it can be seen that the gas is discharged over the shortest distance through the gas discharge hole (③) of the top cap located at the same position as the widest through hole (②).

[0166] Accordingly, in Comparative Example 1, the length of the through hole of the CID filter is reduced by the anode tab, and as the path through which gas flows within the cap assembly becomes longer, the flow velocity of the gas discharge hole of the top cap increases, and the discharge is not smooth, which causes a problem.

[0167] On the other hand, Example 1 has the effect of ensuring smooth gas discharge without increasing the flow rate of the gas discharge hole of the top cap, as the length of the through hole of the CID filter is not reduced and the length of the through hole of the CID filter is formed asymmetrically.

[0168] Figure 8 is a photograph showing the pressure difference between the discharge hole of the top cap (hereinafter, upper part of the positive tab, ①) through which gas is discharged to the outside in the secondary battery according to Example 1 and Comparative Example 1, and the space between the positive tab and the electrode assembly (hereinafter, lower part of the positive tab, ②).

[0169] The upper part of the anode tab in Comparative Example 1 of Fig. 8 is brighter in color (closer to white) than the upper part of the anode tab in Example 1, which means that the pressure in the upper part of the anode tab in Comparative Example 1 is lower than that in the upper part of the anode tab in Example 1, and the lower part of the anode tab in Comparative Example 1 is darker in color than the lower part of the anode tab in Example 1, which means that the pressure in the lower part of the anode tab in Comparative Example 1 is higher than that in the lower part of the anode tab in Example 1.

[0170] In Comparative Example 1, the pressure difference between the upper and lower parts of the anode tab is 3 bar or more, which may cause the anode tab and cap assembly to deform or break, and the problem of the gas discharge path being blocked by the broken parts may occur.

[0171] FIG. 9(a) is a perspective view illustrating a secondary battery according to Comparative Example 2, FIG. 9(b) is a perspective view illustrating a secondary battery according to Example 2, and FIG. 10 is a graph showing the internal pressure of the secondary batteries of Example 2 and Comparative Example 2 over time.

[0172] Referring to FIG. 9(a), Comparative Example 2 shows that the center of one of the two tap holes is located at a position corresponding to the center of the main through hole of the CID filter, and referring to FIG. 9(b), Example 2 shows a case where an additional hole is inserted to improve gas discharge.

[0173] Referring to Fig. 10, it can be seen that the pressure was higher than in Example 2 because gas discharge in Comparative Example 2 was not smooth, and it can also be seen that the pressure decrease over time in Example 2 is wider than in Comparative Example 2. This indicates that if the tap hole of the insulator is blocked by the positive tap, it becomes an obstacle to the discharge of internal gas from the secondary battery to the outside.

[0174]

[0175] Although the present invention has been described above with reference to preferred embodiments, those skilled in the art will understand that various modifications and changes can be made to the invention without departing from the spirit and scope of the invention as described in the following claims.

Claims

1. In a CID (Current Interruptive Device) filter for a secondary battery, A central part located at the center of the above CID filter; A peripheral area located at the edge of the above CID filter; and An intermediate part comprising at least one through hole located along the circumference of the central part and a CID bridge connecting the central part and the peripheral part; A CID filter for a secondary battery, wherein the through hole is positioned asymmetrically with respect to any one line passing through the center point of the CID filter.

2. In paragraph 1, the through hole comprises one main through hole and one or more auxiliary through holes, and A CID filter for a secondary battery, wherein the main through hole and the auxiliary through hole differ in at least one of their length and area.

3. In paragraph 2, the length of the main through hole is longer than the length of the auxiliary through hole, or The area of ​​the main through hole is larger than the area of ​​the auxiliary through hole, or A CID filter for a secondary battery, wherein the length and area of ​​the main through hole are longer and wider than the length and area of ​​the auxiliary through hole.

4. In paragraph 2, the through hole comprises a plurality of auxiliary through holes, and the auxiliary through holes are located adjacent to each other. A CID filter for a secondary battery, wherein the length of the CID bridge located between the auxiliary through holes is longer than the length of the CID bridge located between the main through hole and the auxiliary through hole.

5. A CID filter for a secondary battery according to claim 2, wherein the length of the main through hole is approximately 30% to 70% based on the circumference of the intermediate part passing through the center of the main through hole.

6. Electrode assembly including an electrode and a separator; A battery case that accommodates the above electrode assembly and has an open top; A top cap coupled to the upper part of the battery case above; A safety vent provided at the lower part of the top cap; and A secondary battery comprising: a CID filter for a secondary battery according to claim 1, provided at the lower part of the safety vent and having at least a portion of the upper surface located on the lower part of the safety vent.

7. In paragraph 6, the electrode assembly includes an electrode tab protruding toward the CID filter, and The above electrode tab is a secondary battery that is bonded to the above CID bridge.

8. In claim 7, the through hole comprises one main through hole and one or more auxiliary through holes, and The electrode tab is attached to a CID bridge located between the main through-hole and the auxiliary through-hole, or A secondary battery in which the electrode tab is bonded to a CID bridge located between a plurality of adjacent auxiliary through holes.

9. A secondary battery according to claim 8, wherein the length of the CID bridge located between the main through hole and the auxiliary through hole or the length of the CID bridge located between the auxiliary through holes is equal to the length of the electrode tab or wider than the width of the electrode tab.

10. In claim 6, further comprising an insulator between the electrode assembly and the CID filter, The above-mentioned insulator is a secondary battery comprising a plurality of tap holes.

11. A secondary battery according to claim 10, wherein the center of any one of the plurality of tap holes is located at a position corresponding to the center of the through hole of the CID filter.

12. A battery module including a secondary battery according to paragraph 6.

13. A battery pack including a secondary battery according to paragraph 6.

14. A battery pack including a battery module according to paragraph 12.

15. An electric vehicle including a battery pack pursuant to Paragraph 14.

Images