Rechargeable battery

Abstract

The present invention relates to a secondary battery, wherein the secondary battery according to the present invention comprises: an electrode assembly in which an electrode and a separator are alternately stacked and wound; a cylindrical can having a receiving portion formed to accommodate the electrode assembly and an open top; and a cap assembly covering the opening of the can, wherein the cap assembly includes a safety vent having a notching portion formed therein that ruptures when the internal pressure of the battery increases, wherein the notching portion is formed in a circular shape in a planar view, and the electrode assembly includes an electrode tab connected to the electrode, and the safety vent is connected to the electrode tab and an external terminal, wherein the electrode tab and the external terminal are connected to different sides among the inner and outer sides with respect to the notching portion in a planar view of the safety vent.

Description

Technology Field

[0001] The present invention relates to a secondary battery. Background Technology

[0002] Unlike primary batteries, secondary batteries are rechargeable and are currently the subject of extensive research and development due to their potential for miniaturization and high capacity. As technological development and demand for mobile devices increase, the demand for secondary batteries as an energy source is rising rapidly.

[0003] Secondary batteries are classified into coin batteries, cylindrical batteries, prismatic batteries, and pouch batteries according to the shape of the battery case. In secondary batteries, the electrode assembly mounted inside the battery case is a rechargeable power generation device consisting of a laminated structure of electrodes and separators.

[0004] Electrode assemblies can be roughly classified into a jelly-roll type, which is wound with a separator interposed between sheet-type positive and negative electrodes coated with active material; a stack type, which is sequentially stacked with multiple positive and negative electrodes interposed with a separator; and a stack / folding type, which is wound with unit cells of the stack type wrapped in a long separating film.

[0005] Among these, jelly roll type electrode assemblies are widely used because they have the advantages of being easy to manufacture and having a high energy density per unit weight.

[0006] Cylindrical secondary batteries containing conventional jelly roll-type electrode assemblies are notched at the bottom of the top cap assembly to facilitate the venting of gas inside the battery when an event occurs in which the internal pressure increases.

[0007] In the case of a cylindrical secondary battery without a top cap and a separate CID (current interrupt device), the positive tab of the battery is welded to the lower part inside the notching portion, and the terminal of the pack or application is welded to the upper part so that current flows.

[0008] This current path configuration has a problem in that even if an event occurs inside the battery and causes venting, the current continues to be applied, leading to an explosion.

[0009] Meanwhile, in the case of a conventional cylindrical secondary battery equipped with a top cap and a separate CID (current interrupt device), the CID, safety vent, and top cap are arranged sequentially from the bottom to the top of the cylindrical top cap assembly, and the structure is configured such that the central part of the safety vent is bent downwards and connected to the upper surface of the CID. Furthermore, when gas is generated inside the battery, the central part of the safety vent reverses upwards due to the increase in pressure, releasing the connection between the CID and the safety vent and causing a short circuit; the pressure required for this short circuit is called the CID short-circuit pressure.

[0010] Also, if more gas is generated after the CID is short-circuited, the safety vent tears to release the internal gas, and the pressure at this time is called the venting pressure. Prior art literature

[0011] Korean Published Patent No. 10-2016-0010121 The problem to be solved

[0012] One aspect of the present invention is to provide a secondary battery in which the current can be cut off when venting due to internal factors of the battery. means of solving the problem

[0013] A secondary battery according to an embodiment of the present invention comprises: an electrode assembly in which an electrode and a separator are alternately stacked and wound; a cylindrical can having a receiving portion formed to accommodate the electrode assembly and an open top; and a cap assembly covering the opening of the can, wherein the cap assembly includes a safety vent formed with a notching portion that ruptures when the internal pressure of the battery increases, the notching portion being formed in a circular shape in a planar view, the electrode assembly including an electrode tab connected to the electrode, and the safety vent being connected to the electrode tab and an external terminal, wherein the electrode tab and the external terminal may be connected to different sides among the inner and outer sides based on the notching portion in a planar view of the safety vent.

[0014] Meanwhile, the battery pack according to an embodiment of the present invention may include a secondary battery according to an embodiment of the present invention. Effects of the invention

[0015] According to the present invention, by connecting the electrode tab and the external terminal to different sides among the inner and outer sides based on the notching portion in a planar view of the safety vent, the notching portion ruptures as the internal pressure of the battery increases, and the current can be cut off during venting. Brief explanation of the drawing

[0016] FIG. 1 is a cross-sectional view showing a secondary battery according to one embodiment of the present invention. FIG. 2 is a cross-sectional view showing the state in which the notched portion of a safety vent in a secondary battery according to one embodiment of the present invention is ruptured. FIG. 3 is a cross-sectional view showing a cap assembly of a secondary battery according to one embodiment of the present invention. FIG. 4 is a bottom view showing a safety vent in a secondary battery according to one embodiment of the present invention. FIG. 5 is a cross-sectional view showing a secondary battery according to another embodiment of the present invention. FIG. 6 is a cross-sectional view showing the state in which the notched portion of a safety vent in a secondary battery according to another embodiment of the present invention is ruptured. Specific details for implementing the invention

[0017] The objects, specific advantages, and novel features of the present invention will become more apparent from the following detailed description and preferred embodiments in conjunction with the accompanying drawings. It should be noted that in assigning reference numerals to the components of each drawing in this specification, the same components are assigned the same number whenever possible, even if they are shown in different drawings. Furthermore, the present invention may be embodied in various different forms and is not limited to the embodiments described herein. Also, in describing the present invention, detailed descriptions of related known technologies that could unnecessarily obscure the essence of the invention are omitted.

[0019] A secondary battery according to one embodiment

[0021] FIG. 1 is a cross-sectional view showing a secondary battery according to one embodiment of the present invention, and FIG. 2 is a cross-sectional view showing a state in which the notched portion of a safety vent in a secondary battery according to one embodiment of the present invention is ruptured.

[0022] Referring to FIGS. 1 and 2, a secondary battery (100) according to one embodiment of the present invention comprises an electrode assembly (110) in which electrodes (113) and separators (114) are alternately stacked and wound, a can (120) in which the electrode assembly (110) is received and which is open, and a cap assembly (130) that covers the opening of the can (120). Additionally, the cap assembly (130) includes a safety vent (131) formed with a notching portion (131a) that ruptures when the internal pressure of the battery increases.

[0024] Hereinafter, a secondary battery (100), which is an embodiment of the present invention, will be described in more detail.

[0025] Referring to FIGS. 1 and 2, the electrode assembly (110) is a power generation element capable of charging and discharging, and forms a structure in which an electrode (113) and a separator (114) are assembled and alternately stacked. Here, the electrode assembly (110) may be formed in a wound form in which the electrode (113) and the separator (114) are alternately assembled. At this time, the electrode assembly (110) may be wound in a cylindrical shape wound around a central axis.

[0026] The electrode (113) may include an anode (112) and a cathode (111). And, the separator (114) separates the anode (112) and the cathode (111) to electrically insulate them.

[0027] The positive electrode (112) may include a positive electrode current collector and a positive electrode active material provided on one side of the positive electrode current collector. At this time, the positive electrode (112) may include a positive electrode non-layer, which is an area where the positive electrode active material is not laminated.

[0028] The positive current collector can be made of, for example, aluminum foil.

[0029] The cathode active material may be composed of lithium manganese oxide, lithium cobalt oxide, lithium nickel oxide, lithium iron phosphate, or compounds and mixtures containing one or more of these.

[0030] The negative electrode (111) may include a negative electrode current collector and a negative electrode active material provided on one side of the negative electrode current collector. At this time, the negative electrode (111) may include a negative electrode non-layer, which is an area where the negative electrode active material is not laminated.

[0031] The cathode current collector can be made of, for example, a copper foil made of copper (Cu) material.

[0032] The negative electrode active material may be composed of, for example, artificial graphite, lithium metal, lithium alloy, carbon, petroleum coke, activated carbon, graphite, silicon compound, tin compound, titanium compound, or alloys thereof. In this case, the negative electrode active material may further include, for example, non-graphite-based SiO (silica) or SiC (silicon carbide).

[0033] The separator (114) is made of an insulating material and can insulate between the positive electrode (112) and the negative electrode (111).

[0034] Additionally, the separator (114) may be a multilayer film made of, for example, microporous polyethylene, polypropylene, or a combination thereof, or a polymer film for solid polymer electrolytes or gel-type polymer electrolytes such as polyvinylidene fluoride, polyethylene oxide, polyacrylonitrile, or polyvinylidene fluoride hexafluoropropylene copolymer.

[0036] In the secondary battery (100) according to the present invention, the electrode assembly (110) may include an electrode tab (140) connected to the electrode.

[0037] The electrode tab (140) is attached to the electrode (113) and is electrically connected to the electrode (113).

[0038] The electrode tab (140) may include an anode tab (141) connected to the anode (112) and a cathode tab connected to the cathode (111).

[0039] The positive tab (141) can be formed in the direction where the cap assembly (130) is located, which is the upper direction when referring to FIG. 1.

[0041] The can (120) may be formed in a tubular shape with an open top and a receiving portion (121) in which the electrode assembly (110) is received. At this time, the can (120) may be formed in a cylindrical shape, for example.

[0042] The can (120) may be formed to be bent inward (131b) so that a cap assembly (130) can be mounted, and a beading portion (122) may be formed on the outer side (131c) to form an indentation groove. At this time, the cap assembly (130) may be seated on the beading portion (122) to cover the opening of the can (120).

[0043] The can (120) may include a crimping portion formed to wrap around the edge of the cap assembly (130) on the upper side. Here, the crimping portion (123) may include an outer periphery formed along the length direction of the can (120) and an upper portion perpendicular to the length direction of the can (120).

[0045] FIG. 3 is a cross-sectional view showing a cap assembly of a secondary battery according to one embodiment of the present invention, and FIG. 4 is a bottom view showing a safety vent in a secondary battery according to one embodiment of the present invention.

[0046] Referring to FIGS. 1 to 4, a cap assembly (130) can be mounted on the top of the can (120) to cover the opening of the can (120).

[0047] The cap assembly (130) may include a safety vent (131) formed with a notching portion that ruptures when the internal pressure of the battery increases, and a gasket (132) that seals and insulates the safety vent (131) and the can (120).

[0048] The safety vent (131) can be connected to the electrode tab (140) and the external terminal (150).

[0049] The notching portion (131a) can be formed in a circular shape in a plan view and can be formed in the center of the safety vent (131). That is, the notching portion (131a) can be formed in a circular shape in the center of the bottom view shown in FIG. 4.

[0050] The notching portion (131a) can be formed on the lower surface of the safety vent (131). At this time, the notching portion (131a) can be formed, for example, as a groove with a triangular cross-section.

[0051] The distance between the center axis of the safety vent (131) and the notching portion (131a) can be formed to be less than half the radius of the safety vent (131).

[0052] A safety vent (131) has a rupture portion (R) formed along a notching portion (131a) on the central side, and when the internal pressure of the battery is greater than the venting pressure, the notching portion (131a) ruptures and the rupture portion (R) can be detached from the safety vent (131). Here, venting pressure refers to the pressure at which the internal gas is released by tearing the safety vent (131) due to an increase in internal pressure caused by gas generation inside the battery. Ultimately, when the internal pressure of the battery due to gas generation inside the battery reaches a level greater than the venting pressure, the notching portion (131a) ruptures and the rupture portion (R) detaches from the safety vent (131), thereby cutting off the current.

[0053] A gasket (132) is provided along the outer surface of the safety vent (131) to wrap around the edge of the safety vent (131). At this time, the crimping portion (123) of the can (120) is formed to wrap around the outer side (131c) of the gasket (132) to seal the space between the can (120) and the cap assembly (130).

[0054] Meanwhile, the cap assembly (130) of a secondary battery according to one embodiment of the present invention may be composed of a safety vent (131) and a gasket (132) without a CID (Current Interrupt Device) filter and a CID gasket. Accordingly, the components can be simplified and material costs reduced. Ultimately, there is an effect of reduced battery resistance and improved performance due to the simplification of components.

[0056] Meanwhile, the electrode tab (140) and the external terminal (150) can be connected to different sides among the inner side (131b) and the outer side (131c) based on the notching portion (131a) in a planar view of the safety vent (131). Here, the electrode tab (140) is connected to the outer side (131c) of the notching portion (131a) in a planar view of the safety vent (131), and the external terminal (150) can be connected to the inner side (131b) of the notching portion (131a) in a planar view of the safety vent (131).

[0057] In the electrode tab (140), the positive electrode tab (141) is provided on the upper part of the electrode assembly (110) and connected to the lower part of the safety vent (131), and the external terminal (150) can be connected to the upper part of the safety vent (131).

[0058] Additionally, the positive tab (141) can be welded to the lower part of the safety vent (131), and the external terminal (150) can be welded to the upper part of the safety vent (131).

[0059] The external terminal (150) may be made of a connecting wire of an external pack or application.

[0061] Referring to FIG. 1, a secondary battery (100) according to one embodiment of the present invention configured as described above is configured such that an external terminal (150) is connected to the inner side (131b) and an electrode tab (140) is connected to the outer side (131c) based on the notching portion (131a) in a planar view from the safety vent (131).

[0062] Accordingly, with reference to FIG. 2, when the internal pressure increases due to the increase in internal gas, the notching portion (131a) ruptures and vents, the current can be cut off. That is, when the notching portion (131a) forming a circular notching line in the plan view ruptures, the rupture portion (R) is separated from the safety vent (131), and the electrical connection between the external terminal (150) fixed to the rupture portion (R), which is the inner side (131b) of the safety vent (131), and the electrode tab (140) fixed to the outer side (131c) of the safety vent (131) is released.

[0063] Ultimately, when venting due to increased internal pressure of the battery, the inner side (131b) of the notching portion (131a) connected to the external terminal (150) in the safety vent (131) ruptures and is separated from the outer side (131c) of the notching portion (131a) connected to the electrode tab (140), thereby completely cutting off the current and preventing an explosion caused by continuous current application.

[0065] Secondary battery according to another embodiment

[0067] A secondary battery according to another embodiment will be described below.

[0068] FIG. 5 is a cross-sectional view showing a secondary battery according to another embodiment of the present invention, and FIG. 6 is a cross-sectional view showing a state in which the notched portion of a safety vent in a secondary battery according to another embodiment of the present invention is ruptured.

[0069] Referring to FIGS. 5 and 6, a secondary battery (200) according to another embodiment of the present invention comprises an electrode assembly (110) in which electrodes (113) and separators (114) are alternately stacked and wound, a can (120) that accommodates the electrode assembly (110) and has an opening, and a cap assembly (130) that covers the opening of the can (120). Additionally, the cap assembly (130) includes a safety vent (131) formed with a notching portion (131a) that ruptures when the internal pressure of the battery increases.

[0070] The secondary battery (200) according to another embodiment of the present invention differs from the secondary battery according to the first embodiment described above in the connection position of the electrode tab (240), the external terminal, and the safety vent (131). Therefore, in this embodiment, details that overlap with the first embodiment are omitted or described briefly, and the description focuses on the differences.

[0072] More specifically, the electrode assembly (110) is a power generation element capable of charging and discharging, and forms a structure in which an electrode (113) and a separator (114) are assembled and alternately stacked. Here, the electrode assembly (110) may be formed in a wound form in which the electrode (113) and the separator (114) are alternately assembled. At this time, the electrode assembly (110) may be wound in a cylindrical shape wound around a central axis.

[0073] The electrode (113) may include an anode (112) and a cathode (111). And, the separator (114) separates the anode (112) and the cathode (111) to electrically insulate them.

[0075] In the secondary battery (200) according to the present invention, the electrode assembly (110) may include an electrode tab (240) connected to an electrode (113).

[0076] The electrode tab (240) is attached to the electrode (113) and is electrically connected to the electrode (113).

[0077] The electrode tab (240) may include an anode tab (241) connected to the anode (112) and a cathode tab connected to the cathode (111).

[0078] The positive tab (241) can be formed in the direction where the cap assembly (130) is located, which is the upper direction.

[0080] The can (120) may be formed in a tubular shape with an open top and a receiving portion (121) in which the electrode assembly (110) is received. At this time, the can (120) may be formed in a cylindrical shape, for example.

[0081] The can (120) may be formed to be bent inward (131b) so that a cap assembly (130) can be mounted, and a beading portion (122) may be formed on the outer side (131c) to form an indentation groove. At this time, the cap assembly (130) may be seated on the beading portion (122) to cover the opening of the can (120).

[0082] The can (120) may include a crimping portion formed to wrap around the edge of the cap assembly (130) on the upper side. Here, the crimping portion (123) may include an outer periphery formed along the length direction of the can (120) and an upper portion perpendicular to the length direction of the can (120).

[0084] A cap assembly (130) can be mounted on the top of the can (120) to cover the opening of the can (120).

[0085] The cap assembly (130) may include a safety vent (131) having a notching portion (131a) that ruptures when the internal pressure of the battery increases, and a gasket (132) that seals and insulates the space between the safety vent (131) and the can (120).

[0086] The safety vent (131) can be connected to the electrode tab (240) and the external terminal (250).

[0087] The notching portion (131a) can be formed in the central part of the safety vent (131) in a plan view.

[0088] The distance between the center axis of the safety vent (131) and the notching portion (131a) can be formed to be less than half the radius of the safety vent (131).

[0089] A safety vent (131) has a rupture portion (R) formed along a notching portion (131a) on the central side, and when the internal pressure of the battery is greater than the venting pressure, the notching portion (131a) ruptures and the rupture portion (R) can be detached from the safety vent (131).

[0091] Meanwhile, the electrode tab (240) and the external terminal (250) can be connected to different sides among the inner side (131b) and the outer side (131c) based on the notching portion (131a) in the planar view of the safety vent (131). Here, the electrode tab (240) is connected to the inner side (131b) of the notching portion (131a) in the planar view of the safety vent (131), and the external terminal (250) can be connected to the outer side (131c) of the notching portion (131a) in the planar view of the safety vent (131).

[0092] Meanwhile, the positive electrode tab (241) is provided on the upper part of the electrode assembly (110) and connected to the lower part of the safety vent (131), and the external terminal (250) can be connected to the upper part of the safety vent (131).

[0093] The positive tab (241) can be welded to the lower part of the safety vent (131), and the external terminal (250) can be welded to the upper part of the safety vent (131).

[0094] The external terminal (250) may be made of a connecting wire of an external pack or application.

[0096] Referring to FIG. 5, a secondary battery (200) according to another embodiment of the present invention configured as described above is configured to connect an external terminal (250) to the outer side (131c) based on the notching portion (131a) in a planar view from the safety vent (131), and to connect an electrode tab (240) to the inner side (131b).

[0097] Accordingly, with reference to FIG. 6, when the internal pressure increases due to the increase in internal gas, the current can be cut off when the notching portion (131a) ruptures and vents. That is, when the notching portion (131a) forming a circular notching line in the plan view ruptures, the rupture portion (R) is separated from the safety vent (131), and the electrical connection between the electrode tab (240) fixed to the rupture portion (R), which is the inner side (131b) of the notching portion (131a) in the safety vent (131), and the external terminal (250) connected to the outer side (131c) of the notching portion (131a) is released.

[0098] Ultimately, when venting due to increased internal pressure of the battery, the inner side (131b) of the notching portion (131a) connected to the positive tab (241) at the electrode tab (240) in the safety vent (131) ruptures and is separated from the outer side (131c) of the notching portion (131a) connected to the external terminal (250), thereby completely cutting off the current and preventing an explosion caused by continuous current application.

[0099] At this time, an insulating film is coated on the outer surface of the positive tab (241) so that when the rupture portion (R) is detached from the safety vent (131) and the positive tab (241) fixed to the rupture portion (R) moves, the positive tab (241) can completely block the electrical reconnection by coming into contact with the outer side (131c) of the notching portion (131a) where the external terminal (250) is fixed from the safety vent (131).

[0101] Meanwhile, a battery pack can be configured by including multiple secondary batteries configured as described above. The battery pack can be configured in a form in which multiple secondary batteries are electrically connected and housed in a battery pack case. Here, the multiple secondary batteries can be connected by connecting wires. In this case, the connecting wires can be connected to the upper part of the safety vent from the secondary battery as external terminals.

[0103] Although the present invention has been described in detail through specific embodiments, this is for the purpose of specifically explaining the invention, and the invention is not limited thereto. It should be understood that various implementations are possible by those skilled in the art within the technical scope of the present invention.

[0104] In addition, the specific scope of protection of the invention will be clarified by the appended patent claims. Explanation of the symbols

[0106] 100,200: Secondary battery 110: Electrode assembly 111: Cathode 112: Bipolar 113: Electrode 114: Separator 120: Can 121: Reception Department 122: Bidding Department 123: Creaming Department 130: Cap Assembly 131: Safety vent 131a: Notched part 131b: Medial 131c: Lateral 132: Gasket 140,240: Electrode tab 141,241: Positive tab 150,250: External terminals R: Rupture

Claims

Claim 1 An electrode assembly in which electrodes and separators are alternately stacked and wound; a cylindrical can having a receiving portion formed to accommodate the electrode assembly and an open top; and includes a cap assembly covering the opening of the can, wherein the cap assembly includes a safety vent formed with a notching portion that ruptures when the internal pressure of the battery increases, the notching portion is formed in a circular shape in a planar view, the electrode assembly includes an electrode tab connected to the electrode, and the safety vent is connected to the electrode tab and an external terminal, wherein the electrode tab and the external terminal are connected to different sides among the inner and outer sides with respect to the notching portion in a planar view of the safety vent, the electrode tab is connected to the inner side of the notching portion in a planar view of the safety vent, and the external terminal is connected to the outer side of the notching portion in a planar view of the safety vent, the electrode includes a positive electrode and a negative electrode, the electrode tab includes a positive electrode tab connected to the positive electrode, the positive electrode tab is provided on the upper side of the electrode assembly and is connected to the lower side of the safety vent, and the external terminal is connected to the upper side of the safety vent, and the safety vent has a rupture portion formed in the center that ruptures along the notching portion, and the internal pressure of the battery A secondary battery in which the notching portion ruptures when the venting pressure is above the level, the ruptured portion detaches from the safety vent, and an insulating film is coated on the outer surface of the positive electrode tab. Claim 2 delete Claim 3 delete Claim 4 delete Claim 5 A secondary battery according to claim 1, wherein the positive tab is welded to the lower part of the safety vent and the external terminal is welded to the upper part of the safety vent. Claim 6 A secondary battery according to claim 1, wherein the external terminal is a connecting wire of an external pack or application. Claim 7 A secondary battery according to claim 1, wherein the notching portion is formed in the central portion of the safety vent in a planar view. Claim 8 A secondary battery according to claim 1, wherein the cap assembly further comprises a gasket that seals and insulates the safety vent and the can, and the can comprises a crimping portion formed to wrap the gasket on its upper side and secure the cap assembly. Claim 9 A secondary battery according to claim 1, wherein the distance between the central axis of the safety vent and the notching portion is formed to be less than or equal to half the radius of the safety vent. Claim 10 delete Claim 11 A battery pack comprising a secondary battery as described in any one of claim 1 and claims 5 to 9.

Images