WO2018030679A1 - Cap assembly for preventing electrical shorting and secondary battery including the same - Google Patents

Cap assembly for preventing electrical shorting and secondary battery including the same Download PDF

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Publication number
WO2018030679A1
WO2018030679A1 PCT/KR2017/008082 KR2017008082W WO2018030679A1 WO 2018030679 A1 WO2018030679 A1 WO 2018030679A1 KR 2017008082 W KR2017008082 W KR 2017008082W WO 2018030679 A1 WO2018030679 A1 WO 2018030679A1
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WO
WIPO (PCT)
Prior art keywords
cap assembly
cap
assembly according
elastic plate
secondary battery
Prior art date
Application number
PCT/KR2017/008082
Other languages
French (fr)
Inventor
Gi Rin Kim
Man Yong HWANG
Takao Abe
Jong Ho Kim
Original Assignee
Shin Heung Energy & Electronic Co.,Ltd.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from KR1020170047404A external-priority patent/KR20180018279A/en
Application filed by Shin Heung Energy & Electronic Co.,Ltd. filed Critical Shin Heung Energy & Electronic Co.,Ltd.
Publication of WO2018030679A1 publication Critical patent/WO2018030679A1/en

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/04—Construction or manufacture in general
    • H01M10/0422—Cells or battery with cylindrical casing
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/572—Means for preventing undesired use or discharge
    • H01M50/584—Means for preventing undesired use or discharge for preventing incorrect connections inside or outside the batteries
    • H01M50/59—Means for preventing undesired use or discharge for preventing incorrect connections inside or outside the batteries characterised by the protection means
    • H01M50/591—Covers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/10—Primary casings; Jackets or wrappings
    • H01M50/147—Lids or covers
    • H01M50/166—Lids or covers characterised by the methods of assembling casings with lids
    • H01M50/169—Lids or covers characterised by the methods of assembling casings with lids by welding, brazing or soldering
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/10—Primary casings; Jackets or wrappings
    • H01M50/147—Lids or covers
    • H01M50/166—Lids or covers characterised by the methods of assembling casings with lids
    • H01M50/171—Lids or covers characterised by the methods of assembling casings with lids using adhesives or sealing agents
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/30—Arrangements for facilitating escape of gases
    • H01M50/342—Non-re-sealable arrangements
    • H01M50/3425—Non-re-sealable arrangements in the form of rupturable membranes or weakened parts, e.g. pierced with the aid of a sharp member
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/572—Means for preventing undesired use or discharge
    • H01M50/574—Devices or arrangements for the interruption of current
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/572—Means for preventing undesired use or discharge
    • H01M50/584—Means for preventing undesired use or discharge for preventing incorrect connections inside or outside the batteries
    • H01M50/588—Means for preventing undesired use or discharge for preventing incorrect connections inside or outside the batteries outside the batteries, e.g. incorrect connections of terminals or busbars
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/572—Means for preventing undesired use or discharge
    • H01M50/584—Means for preventing undesired use or discharge for preventing incorrect connections inside or outside the batteries
    • H01M50/59—Means for preventing undesired use or discharge for preventing incorrect connections inside or outside the batteries characterised by the protection means
    • H01M50/593—Spacers; Insulating plates
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • the present invention relates to a cap assembly for preventing electrical shorting in a secondary battery and a secondary battery including the cap assembly. More specifically, thepresentinvention relatestoa cap assembly that prevents the occurrence of electrical shorting in a secondary battery when a gasket between a battery can and the cap assembly and/or an insulating layer between a safety vent and a cap-down is dissolved or lost upon abnormal operation of the secondary battery so that the battery can is brought into close contact with the cap assembly and/or the safety vent is brought into close contact with the cap-down and a secondary battery including the cap assembly.
  • Secondary batteries are classified into cylindrical, prismatic, and pouch types depending on the shape of battery cases they employ.
  • the cylindrical batteries include an electrode assembly accommodated in a cylindrical metal can.
  • the prismatic batteries include an electrode assembly accommodated in a prismatic metal can.
  • the pouch type batteries include an electrode assembly accommodated in a pouch type case made of an aluminum laminate sheet.
  • Electrode assemblies accommodated in battery cases are power generating devices capable of repeated charge/discharge cycles that have a cathode/separator/anode laminate structure. Electrode assemblies are classified into jelly-roll and stack types by their structure.
  • the jelly-roll type structure is constructed by interposing a separator between an anode and a cathode, each of which is in the form of a long sheet coated with an active material, and winding the laminate in a roll form.
  • the stack type structure is constructed by sequentially stacking a plurality of electrode units, each of which includes a cathode having a predetermined size, an anode having a predetermined size, and a separator interposed therebetween.
  • the jelly-roll type electrode assemblies are most widely used in secondary batteries due to their ease of construction and high energy density per unit weight.
  • the jelly-roll type electrode assemblies are usually employed in cylindrical batteries.
  • Heat generated by internal short-circuiting decomposes organic solvents to produce gases.
  • the gases increase the internal gas pressure of batteries to burst the batteries.
  • An increase in the internal gas pressure of batteries may take place also when internal short-circuiting is caused by an external impact.
  • a cap assembly for a cylindrical battery having a structure in which a safety vent, safety devices, and a top cap are fixed by a gasket. High-pressure gases are released through the safety vent.
  • the safety devices include a current interrupt device (CID) adapted to interrupt the flow of electric current when the internal pressure of the battery increases.
  • the top cap forms a protruding terminal adapted to protect the safety devices.
  • the gasket surrounds the outer circumferences of the safety vent, the PTC device, the CID, the top cap, etc. to essentially prevent an electrolyte from leaking out from the battery. So long as the electrolyte is prevented from leaking through the interface between the innermost safety vent of the battery and the gasket surrounding the outer circumference of the safety vent, there is no leakage of the electrolyte through the interfaces between the metal parts, such as the interface between the safety vent and the PTC device and the interface between the PCT device and the top cap.
  • a portion of the electrolyte leaks substantially through the interface between the gasket and the safety vent during charge/discharge of the battery, when the battery falls down or when an external impact is applied to the battery.
  • the leaking electrolyte easily escapes from the battery through the interfaces between the metal parts. That is, due to relatively weak adhesiveness at the interfaces between the metal parts, the electrolyte entering the interfaces between the metal parts easily leaks out of the cap assembly through the interfaces between the metal parts compared to through the interfaces between the gasket and the related devices.
  • the electrolyte may be evaporated by heat generated upon abnormal operation in the can of the secondary battery.
  • Korean Patent Publication No. 2012-103394 discloses a secondary battery including an electrode assembly 10, a can 20 accommodating the electrode assembly 10, a cap assembly 30 sealing the can 20, a lower insulating plate 40, an upper insulating plate 50, a center pin 60, and an insulating gasket 70, as illustrated in Figs. 16 and 17.
  • the insulating gasket 70 is positioned between the can 20 and the cap assembly 30 having opposite polarities.
  • the insulating gasket 70 together with the cap assembly 30 seals the can 20 while insulating the can 20 from the cap assembly 30.
  • the cap assembly 30 is fitted into the insulating gasket 70.
  • the cap assembly 30 includes a top cap 31 acting as an electrode terminal, a vent 32, an insulator 33, a current interrupt device 34, and a sub-plate 35.
  • the vent 32, the insulator 33, the current interrupt device 34, and the sub-plate 35 are positioned in this order on the top cap 31.
  • the current interrupt device 34 is positioned on the electrode assembly.
  • the current interrupt device 34 is electrically connected to a first electrode tab of the electrode assembly through the sub-plate 35, which is interposed between the current interrupt device and the first electrode tab.
  • the current interrupt device 34 functions to interrupt the flow of electric current upon abnormal operation of the battery.
  • the vent 32 is positioned on and in electrical contact with the current interrupt device 34. The vent 32 ruptures when the internal pressure of the can is increased by gases produced in the electrode assembly.
  • the vent 32 functions to decrease the internal pressure of the can.
  • the vent 32 has a downwardly protruding portion 321 in contact with the current interrupt device 34 in the normal state of the battery.
  • the protrusion 321 moves upward when the internal pressure of the can increases upon abnormal operation of the battery, and as a result, the vent 32 and the current interrupt device 34 are electrically opened to interrupt the flow of electric current.
  • the vent 32 and the current interrupt device 34 are isolated from each other to interrupt the flow of electric current, the internal pressure of the can may continue to increase. In this case, the vent 32 ruptures such that the gases are released from the can to the outside, and as a result, the battery is free from any danger of explosion.
  • the vent 32 is made of one or more material selected from aluminum, aluminum alloy, and shape memory alloys.
  • the protrusion 321 is constructed such that it shrinks at a high temperature.
  • the protrusion 321 may be constructed such that it protrudes downward at a normal temperature and protrudes upward at a predetermined temperature (e . g ., 100 °C). Due to this construction, the vent 32 and the current interrupt device 34 are electrically isolated from each other at the predetermined temperature so that the flow of electric current can be interrupted.
  • the top cap 31 is electrically connected to a PTC thermistor 36 through a conductive adhesive 37, for example, a silver paste, or by soldering. This electrical connection allows the top cap 31 to act as an electrode terminal.
  • the gasket surrounding the outer circumference of the cap assembly to seal the cap assembly may be melted or lost by heat generated in the secondary battery or an electrolyte.
  • the cap assembly is changed in shape.
  • the gasket and an insulating layer interposed between metal parts (such as a cap-up, a safety vent, and a cap-down) as current-carrying members are corroded and lost by the leaking electrolyte or its gases and are physically attached to each other, causing electrical shorting.
  • the present invention has been made in view of the above problems, and it is a first object of the present invention to provide a cap assembly that prevents the occurrence of electrical shorting in a secondary battery when a gasket between a battery can and the cap assembly and/or an insulating layer between a safety vent and a cap-down is dissolved or lost upon abnormal operation of the secondary battery so that the battery can is brought into close contact with the cap assembly and/or the safety vent is brought into close contact with the cap-down. It is a second object of the present invention to provide a secondary battery including the cap assembly.
  • a first aspect of the present invention provides acapassemblyforpreventingelectricalshortinginasecondarybattery,includingacap-upattachedwithanelasticplateadaptedtointerrupttheflowofelectriccurrentbyinternalheatofthesecondarybattery,aCIDmoduleinterruptingtheflowofelectriccurrentbyinternalpressureofthesecondarybattery,andaninsulatingmemberinterposedbetweenthecap-upandtheCIDmodule.
  • the cap-up may include a flange connected to a flat terminal through a portion extending obliquely from the terminal to form the rim of the terminal.
  • the insulating member may be interposed between the cap-up and an elastic support.
  • the terminal may be fixed to and in electrical communication with one end of the elastic plate through a welding portion or a soldering portion.
  • the other end of the elastic plate may be fixed to and in electrical communication with the elastic support through a welding portion or a soldering portion.
  • each of the soldering portions may be formed by melting a soldering material and solidifying the molten soldering material and the soldering material may include bismuth.
  • the bismuth may be present in an amount of 50 to 65% by weight, based on the total weight of the soldering material.
  • the soldering material may have a melting point of 130 to 300 °C.
  • the soldering portion fixing the terminal to the one end of the elastic plate may be melted by heat generated in the secondary battery to allow the elastic plate to be restored downward.
  • the soldering portion fixing the other end of the elastic plate to the elastic support may be melted by heat generated in the secondary battery to allow the elastic plate to be restored upward.
  • the side of the flange opposite to the elastic plate may be perforated to form a through-hole adapted to prevent the elastic plate from interfering with the flange of the cap-up upon when the elastic plate is restored upward.
  • the end portion of a safety vent of the CID module may be bent to surround the end portion of the elastic support.
  • the terminal may further have an entrance hole through which a pressurizing member can reach the elastic plate.
  • the elastic plate may have a central portion protruding toward the terminal.
  • the central portion may be perforated with at least one slit for elasticity control.
  • both ends of the elastic plate may be first and second welding portions where the flange is welded.
  • the first and second welding portions may be formed by welding or diffusion-bonding.
  • a current-carrying part may be interposed between the CID module and the central portion by pressurizing the central portion, melting a soldering material on the elastic plate, and solidifying the molten soldering material.
  • the elastic plate may be made of copper or a copper alloy.
  • the cap assembly may further include an attachment layer bonded to an area of the CID module facing the current-carrying part when the molten soldering material is solidified.
  • the attachment layer may include nickel, a nickel alloy, tin, zinc, chromium, molybdenum, titanium or niobium.
  • the soldering material may include bismuth.
  • the soldering material may have a melting point of 130 to 300 °C.
  • the bismuth may be present in an amount of 50 to 65% by weight, based on the total weight of the soldering material.
  • the CID module may include a safety vent having a central protrusion, a cap-down having a central opening portion arranged opposite to the protrusion, a second insulating member interposed between the safety vent and the cap-down such that the protrusion and the central portion are exposed, and a sub-plate fixed so as to cover the central portion and having a welding portion weld-attached to the protrusion.
  • the CID module may include a safety vent having a central protrusion, a cap-down having a breakable portion in direct contact with the protrusion, and a second insulating member interposed between the safety vent and the cap-down such that the protrusion is exposed.
  • a second aspect of the present invention provides a secondary battery including the cap assembly.
  • the cap assembly can prevent the occurrence of electrical shorting in a secondary battery when a gasket between a battery can and the cap assembly and/or an insulating layer between a safety vent and a cap-down is dissolved or lost upon abnormal operation of the secondary battery so that the battery can is brought into close contact with the cap assembly and/or the safety vent is brought into close contact with the cap-down.
  • Fig. 1 is a cross-sectional view illustrating one embodiment of a cap assembly of the present invention.
  • Fig. 2 is a bottom view illustrating a cap-up of a cap assembly according to the present invention in which a welding portion and a soldering portion are formed on a terminal and an elastic support, respectively.
  • Fig. 3 illustrates cross-sectional views explaining a process for manufacturing a cap assembly including (a) forming a soldering portion between an elastic plate and an elastic support, (b) assembling the elastic support and a cap-up by interposing an insulating member therebetween, (c) bonding a terminal to one end of the elastic plate, and (d) bending the end portion of a safety vent of a CID module to surround the end portion of the elastic support.
  • Fig. 4 illustrates a shape in which the other end of an elastic plate is restored upward when a soldering portion formed on an elastic support is melted by internal heat of a secondary battery.
  • Fig. 5 is a bottom view illustrating a cap-up of a cap assembly according to the present invention in which a soldering portion and a welding portion are formed on a terminal and an elastic support, respectively.
  • Fig. 6 illustrates a shape in which one end of an elastic plate is restored downward when a soldering portion formed on a terminal is melted by internal heat of a secondary battery.
  • Fig. 7 is a cross-sectional view illustrating a further embodiment of a cap assembly according to the present invention.
  • Fig. 8 is a cross-sectional view illustrating another embodiment of a cap assembly according to the present invention.
  • Fig. 9 is a plan view illustrating a cap-up and an elastic plate attached to the cap-up in a cap assembly of the present invention.
  • Fig. 10 illustrates a further embodiment of the elastic plate illustrated in Fig. 9.
  • Fig. 11 is a cross-sectional view of the cap-up illustrated in Fig. 9.
  • Fig. 12 is a cross-sectional view illustrating a shape in which a pressurizing member enters through an entrance hole of a cap-up to push an elastic plate and a shape in which a soldering material is applied to the elastic plate.
  • Fig. 13 is a cross-sectional view illustrating a shape in which an insulating member and a CID module are aligned with the pushed elastic plate illustrated in Fig. 12.
  • Fig. 14 is a cross-sectional view illustrating a shape in which a current-carrying part is formed by bonding the pushed elastic plate, the insulating member, and the CID module aligned in Fig. 13, dissolving the soldering material by heating, and solidifying the soldering material.
  • Fig. 15 illustrates cross-sectional views of a cap assembly according to the present invention: (a) a cross-sectional view of the cap assembly during normal operation of a secondary battery and (b) a cross-sectional view illustrating a shape in which a current-carrying part is melted by heat generated upon abnormal operation of the secondary battery and an elastic plate is restored by its elasticity to interrupt the flow of electric current.
  • Fig. 16 is an exploded perspective view of a conventional cylindrical secondary battery.
  • Fig. 17 is an exploded perspective view of an electrode assembly accommodated in a battery can of the secondary battery illustrated in Fig. 16.
  • Fig. 18 is a cross-sectional view illustrating a shape in which a gasket between a cap assembly and a battery can and/or an insulating layer between a safety vent and a cap-down is dissolved or lost to cause short-circuiting of a conventional secondary battery.
  • Fig. 1 is a cross-sectional view illustrating one embodiment of a cap assembly of the present invention
  • Fig. 2 is a bottom view illustrating a cap-up of a cap assembly according to the present invention in which a welding portion and a soldering portion are formed on a terminal and an elastic support, respectively
  • Fig. 1 is a cross-sectional view illustrating one embodiment of a cap assembly of the present invention
  • Fig. 2 is a bottom view illustrating a cap-up of a cap assembly according to the present invention in which a welding portion and a soldering portion are formed on a terminal and an elastic support, respectively
  • FIG. 3 illustrates cross-sectional views explaining a process for manufacturing a cap assembly including (a) forming a soldering portion between an elastic plate and an elastic support, (b) assembling the elastic support and a cap-up by interposing an insulating member therebetween, (c) bonding a terminal to one end of the elastic plate, and (d) bending the end portion of a safety vent of a CID module to surround the end portion of the elastic support,
  • Fig. 4 illustrates a shape in which the other end of an elastic plate is restored upward when a soldering portion formed on an elastic support is melted by internal heat of a secondary battery, Fig.
  • FIG. 5 is a bottom view illustrating a cap-up of a cap assembly according to the present invention in which a soldering portion and a welding portion are formed on a terminal and an elastic support, respectively
  • Fig. 6 illustrates a shape in which one end of an elastic plate is restored downward when a soldering portion formed on a terminal is melted by internal heat of a secondary battery
  • Fig. 7 is a cross-sectional view illustrating a further embodiment of a cap assembly according to the present invention
  • Fig. 8 is a cross-sectional view illustrating another embodiment of a cap assembly according to the present invention
  • Fig. 9 is a plan view illustrating a cap-up and an elastic plate attached to the cap-up in a cap assembly of the present invention
  • FIG. 10 illustrates a further embodiment of the elastic plate illustrated in Fig. 9, Fig. 11 is a cross-sectional view of the cap-up illustrated in Fig. 9, Fig. 12 is a cross-sectional view illustrating a shape in which a pressurizing member enters through an entrance hole of a cap-up to push an elastic plate and a shape in which a soldering material is applied to the elastic plate, Fig. 13 is a cross-sectional view illustrating a shape in which an insulating member and a CID module are aligned with the pushed elastic plate illustrated in Fig. 12, Fig.
  • FIG. 14 is a cross-sectional view illustrating a shape in which a current-carrying part is formed by bonding the pushed elastic plate, the insulating member, and the CID module aligned in Fig. 13, dissolving the soldering material by heating, and solidifying the soldering material
  • Fig. 15 illustrates cross-sectional views of a cap assembly according to the present invention: (a) a cross-sectional view of the cap assembly during normal operation of a secondary battery and (b) a cross-sectional view illustrating a shape in which a current-carrying part is melted by heat generated upon abnormal operation of the secondary battery and an elastic plate is restored by its elasticity to interrupt the flow of electric current, Fig.
  • FIG. 16 is an exploded perspective view of a conventional cylindrical secondary battery
  • Fig. 17 is an exploded perspective view of an electrode assembly accommodated in a battery can of the secondary battery illustrated in Fig. 16
  • Fig. 18 is a cross-sectional view illustrating a shape in which a gasket between a cap assembly and a battery can and/or an insulating layer between a safety vent and a cap-down is dissolved or lost to cause short-circuiting of a conventional secondary battery.
  • a cap assembly 100 of the present invention is designed to prevent electrical shorting in a secondary battery.
  • the cap assembly 100 includes: a cap-up 300 attached with an elastic plate 200 adapted to interrupt the flow of electric current by internal heat of the secondary battery; a CID module 500 interrupting the flow of electric current by internal pressure of the secondary battery; and an insulating member 400 interposed between the cap-up and the CID module.
  • the elastic plate 200 is attached to the bottom of the cap-up 300 and acts as a terminal through which power generated in an electrode assembly is supplied to an external circuit or load.
  • the flow of electric current through the elastic plate is interrupted by heat generated upon abnormal operation of the secondary battery.
  • the cap-up 300 includes a flange 320 connected to a flat terminal 310 through an extension 330 to form the rim of the terminal.
  • the extension 330 extends obliquely downward from the terminal and acts as an electrode terminal of the cap-up.
  • the extension 330 may also have an air vent hole 340 as a space through which gases produced in the secondary battery are released to the outside.
  • the elastic plate 200 is a plate with elasticity that returns to its original shape when an external force is removed.
  • the elastic plate 200 is a constituent element of the electric circuit of the secondary battery. When heat generated in the secondary battery is above a predetermined level, the elastic plate 200 returns to its original shape by its elasticity to interrupt the flow of electric current.
  • the material for the elastic plate there is no particular restriction on the material for the elastic plate. Any suitable electric current-carrying material may be used for the elastic plate.
  • the elastic plate may be made of copper or a copper alloy.
  • one end 201 of the elastic plate 200 may be attached to the terminal 310 by laser welding, ultrasonic welding or soldering as to be in electrical communication with the terminal 310.
  • a welding or diffusion-bonding method such as ultrasonic welding, laser welding or resistance welding, is suitable for the formation of a welding portion WP that is maintained attached to the terminal 310 despite internal heat of the secondary battery.
  • soldering is suitable for the formation of a soldering portion that is detached and electrically disconnected from the terminal 310 by internal heat of the secondary battery.
  • the soldering portion may be formed by melting (or dissolving) a soldering material S by soldering and solidifying the molten soldering material at a low temperature.
  • melting and “dissolution” are used interchangeably herein to mean that a solid is melted into a liquid or highly flowable fluid.
  • the terms may be used to express a phenomenon that the soldering material is melted.
  • the soldering material contains bismuth or includes zinc and a tin alloy.
  • the soldering material has a low melting point in the range of 130 to 300 °C. Within this range, the insulating member 400 can be prevented from being melted or degraded during dissolution of the soldering material.
  • the soldering material may further contain an auxiliary metal, such as silver, and/or a flux for melting point control.
  • the bismuth may be used in an amount of 50 to 65% by weight, based on the weight of the low-melting-point solder layer. If the bismuth is used in an amount of less than 50% by weight, the increased tin content may increase the melting point of the soldering material. Meanwhile, if the bismuth is used in an amount exceeding 65% by weight, the melting point of the soldering material may be reduced but the contact resistance may be difficult to control.
  • the other end 202 of the elastic plate can electrically connect the cap-up to the CID module 500 by welding or soldering an elastic support (ES).
  • the elastic support (ES) and the cap-up are arranged to face each other through the insulating member 400.
  • the other end 202 of the elastic plate is connected to the elastic support through a soldering portion SP.
  • the other end 202 of the elastic plate is connected to the elastic support through a welding portion WP.
  • the cap assembly of the present invention is distinguished in that when internal heat generated in the secondary battery upon abnormal operation of the secondary battery is applied to the cap-up 300 and the elastic support ES, the solder S of the soldering portion formed on the cap-up 300 or the elastic support ES is dissolved and the elastic plate 200 is restored by its elasticity to interrupt the flow of electric current.
  • the welding portion formed at the one end 201 of the elastic plate allows for upward elastic restoration (P up )oftheelasticplate,andasaresult,theotherend202oftheelasticplateisdetachedfromtheelasticsupport.
  • a through-hole 322 is formed in the corresponding region of the flange opposite to the other end of the elastic plate such that the other end of the elastic plate is prevented from interfering with the flange when detached from the elastic support.
  • the side of the insulating member opposite to the other end of the elastic plate is also exposed through the through-hole.
  • the welding portion formed at the other end of the elastic plate allows for downward elastic restoration (P down )oftheelasticplate,andasaresult,theoneend201oftheelasticplateisdetachedfromtheelasticsupport.
  • the elastic plate 200 may be attached to the cap-up and the elastic support by welding or soldering the one end 201 and the other end 202 of the elastic plate 200 to the terminal and the elastic support, respectively.
  • the order of the welding or soldering is arbitrary.
  • the welding or soldering is performed in such a manner that a welding portion or a soldering portion is formed on the elastic support and then a welding portion or a soldering portion is formed on the terminal of the cap-up.
  • the CID module 500 is attached to the bottom of the elastic support so as to be in electrical communication with the elastic support.
  • the CID module 500 includes a safety vent 510 having a central protrusion, a cap-down 530 having a central opening portion arranged opposite to the protrusion, a second insulating member 520 interposed between the safety vent and the cap-down portion such that the protrusion and the central portion are exposed, and a sub-plate 540 fixed so as to cover the central portion and having a welding portion weld-attached to the protrusion.
  • the CID module 500 upon abnormal operation of the secondary battery, a high pressure generated in the secondary battery is applied to the safety vent 510 toward the outside to break the welding portion of the sub-plate, resulting in the interruption of electric current simultaneously with removal of the pressure.
  • the end portion of the safety vent 510 of the CID module may be bent to surround the end portion of the elastic support to improve the adhesion and sealing of the CID module to/against the elastic support ES.
  • the cap-up 300 attached with the elastic plate 200 may be fastened to an opening of a battery can 20 of the secondary battery in a state in which the cap-up and the CID module are assembled together through the insulating member 400.
  • the CID module 500 may include a safety vent 510 having a central protrusion, a cap-down 530 having a breakable portion in direct contact with the protrusion, and a second insulating member 520 interposed between the safety vent and the cap-down such that the protrusion is exposed. That is, the CID module 500 has a structure in which the sub-plate is removed such that the safety vent is in direct electrical communication with the cap-down. According to the structure of the CID module 500, upon abnormal operation of the secondary battery, a high pressure generated in the secondary battery is applied to the safety vent 510 toward the outside to cut notches formed in the breakable portion, resulting in the interruption of electric current simultaneously with removal of the pressure.
  • the secondary battery is fabricated by assembling the cap assembly 100 with an electrode assembly 10, a can 20 accommodating the electrode assembly 10, a lower insulating plate 40 sealing the can 20, an upper insulating plate 50, a center pin 60, and an insulating gasket 70.
  • the terminal 310 of the cap-up may have an entrance hole 350.
  • the entrance hole 350 is a space through which a pressurizing member 800 can reach the elastic plate 200, which will be described below.
  • the entrance hole 350 is preferably positioned at the center of the terminal. This position is effective in interrupting the flow of electric current through the elastic plate when a current-carrying part 600 is heated, which will be described below.
  • the elastic plate has a central portion 210 protruding toward the terminal.
  • a slope 220 is formed along the extension 330 to form the rim of the central portion.
  • First and second welding portions 230 and 230' are attached to the flange 320 and extend from the slope.
  • any suitable method may be used to attach the first and second welding portions 230 and 230' to the flange 320 so long as the flow of electric current can be ensured.
  • the first and second welding portions 230 and 230' are attached to the flange 320 by welding or diffusion-bonding.
  • suitable welding methods include ultrasonic welding, laser welding, and resistance welding.
  • At least one slit SL for elasticity control may be arranged in the central portion 210 or the slope 220.
  • the arrangement of the slit facilitates controls over the interruption of electric current from the beginning of dissolution of a soldering material S till complete dissolution is reached, which will be explained below.
  • the slit SL may be present only in the inner surface of the central portion or the slope.
  • the slit may penetrate through the inner surface of the central portion or the slope and may extend to the opposite end of the central portion or the slope (see Fig. 10). In this case, precise interruption of electric current can be achieved.
  • the material for the elastic plate there is no particular restriction on the material for the elastic plate. Any suitable electric current-carrying material may be used for the elastic plate.
  • the elastic plate may be made of copper or a copper alloy.
  • the cap-up 300 attached with the elastic plate 200 may be fastened to an opening of the battery can 20 of the secondary battery in a state in which the cap-up and the CID module are assembled together through the insulating member.
  • the insulating member is interposed and insulates between the cap-up and the CID module.
  • a portion of the central portion 210 is pressurized, and as a result, it comes into contact with the safety vent 510 of the CID module 500.
  • a soldering material is arranged and dissolved between the central portion 210 and the safety vent 510. Then, the soldering material is solidified at a low temperature to form a melt-bonded current-carrying part 600.
  • melting and “dissolution” are used interchangeably herein to mean that a solid is melted into a liquid or highly flowable fluid.
  • the terms may be used to express a phenomenon that the soldering material is melted.
  • the soldering material for the current-carrying part 600 contains bismuth or includes zinc and a tin alloy.
  • the soldering material has a low melting point in the range of 130 to 300 °C. Within this range, the insulating member 400 can be prevented from being melted or degraded during dissolution of the soldering material.
  • the soldering material may further contain an auxiliary metal, such as silver, and/or a flux for melting point control.
  • the bismuth may be used in an amount of 50 to 65% by weight, based on the weight of the low-melting-point solder layer. If the bismuth is used in an amount of less than 50% by weight, the increased tin content may increase the melting point of the soldering material. Meanwhile, if the bismuth is used in an amount exceeding 65% by weight, the melting point of the soldering material may be reduced but the contact resistance may be difficult to control.
  • the cap assembly may further include an attachment layer 700 bonded to an area of the CID module facing the current-carrying part 600 where the molten soldering material is solidified.
  • the attachment layer may be formed using nickel, a nickel alloy, tin, zinc, chromium, molybdenum, titanium or niobium, which can be coated by physical vapor deposition, chemical vapor deposition or plating.
  • the CID module 500 may include a safety vent 510 having a central protrusion, a cap-down 530 having a central opening portion arranged opposite to the protrusion, a second insulating member 520 interposed between the safety vent and the cap-down portion such that the protrusion and the central portion are exposed, and a sub-plate 540 fixed so as to cover the central portion and having a welding portion weld-attached to the protrusion.
  • a high pressure generated in the secondary battery is applied to the safety vent 510 toward the outside to break the welding portion of the sub-plate, resulting in the interruption of electric current simultaneously with removal of the pressure.
  • the CID module 500 may include a safety vent 510 having a central protrusion, a cap-down 530 having a breakable portion in direct contact with the protrusion, and a second insulating member 520 interposed between the safety vent and the cap-down such that the protrusion is exposed. That is, the CID module 500 has a structure in which the sub-plate is removed such that the safety vent is in direct electrical communication with the cap-down. According to the structure of the CID module 500, upon abnormal operation of the secondary battery, a high pressure generated in the secondary battery is applied to the safety vent 510 toward the outside to cut notches formed in the breakable portion, resulting in the interruption of electric current simultaneously with removal of the pressure.
  • the secondary battery is fabricated by assembling the cap assembly 100 with an electrode assembly 10, a can 20 accommodating the electrode assembly 10, a lower insulating plate 40 sealing the can 20, an upper insulating plate 50, a center pin 60, and an insulating gasket 70.
  • the method of the present invention includes aligning an elastic plate adapted to interrupt the flow of electric current by internal heat of the secondary battery with a cap-up to form first and second welding portions (step S1), inserting a pressurizing member through an entrance hole to press the elastic plate and loading a soldering material on the elastic plate (step S2), and aligning a CID module and an insulating member with the elastic plate and dissolving the soldering material by heating to form a current-carrying part (step S3).
  • an elastic plate adapted to interrupt the flow of electric current by internal heat of the secondary battery is aligned with a cap-up to form first 230 and second welding portions 230'.
  • the cap-up 300 includes a terminal 310, an extension 330, and a flange 320.
  • the elastic plate 200 includes a central portion 210 and a slope 220.
  • Examples of methods for forming the first and second welding portions include, but are not necessarily limited to, laser welding, resistance welding, friction welding, and ultrasonic welding by which the first and second welding portions can be dissolved and welded.
  • the first and second welding portions it is beneficial in forming the first and second welding portions to irradiate a laser beam onto the elastic plate made of copper or a copper alloy rather than onto the cap-up.
  • a pressurizing member is inserted through an entrance hole to press the elastic plate and a soldering material is loaded on the elastic plate.
  • the cap-up 300 includes a flat terminal 310, an extension 330, and a flange 320.
  • the entrance hole is a space through which the pressurizing member 800 can reach the elastic plate 200 and may be positioned at the center of the terminal.
  • the soldering material is the same as that described above and its explanation is omitted herein.
  • a CID module and an insulating member are aligned with the cap-up welded to the elastic plate and the soldering material is dissolved by heating to form a current-carrying part.
  • a CID module 500 is arranged opposite to the elastic plate 200.
  • an insulating member 400 is aligned such that it is interposed between the CID module and the elastic plate.
  • the CID module 500 and the elastic plate 200 are brought into intimate contact with the insulating member 400.
  • the CID module is heated to dissolve the soldering material S.
  • the dissolved soldering material is solidified (by removing the heating element) to form a current-carrying part 600.
  • the pressurizing member 800 is pulled back to manufacture the cap assembly of the present invention.
  • Cap assembly 200 Elastic plate
  • Terminal 320 Flange
  • CID module 600 Current-carrying part

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Abstract

The present invention relates to a cap assembly for preventing electrical shorting in a secondary battery and a secondary battery including the cap assembly. The cap assembly includes a cap-up attached with an elastic plate adapted to interrupt the flow of electric current by internal heat of the secondary battery, a CID module interrupting the flow of electric current by internal pressure of the secondary battery, and an insulating member interposed between the cap-up and the CID module. The cap assembly prevents the occurrence of electrical shorting in a secondary battery when a gasket between a battery can and the cap assembly and/or an insulating layer between a safety vent and a cap-down is dissolved or lost upon abnormal operation of the secondary battery so that the battery can is brought into close contact with the cap assembly and/or the safety vent is brought into close contact with the cap-down.

Description

CAP ASSEMBLY FOR PREVENTING ELECTRICAL SHORTING AND SECONDARY BATTERY INCLUDING THE SAME
The present invention relates to a cap assembly for preventing electrical shorting in a secondary battery and a secondary battery including the cap assembly. More specifically, thepresentinventionrelatestoa cap assembly that prevents the occurrence of electrical shorting in a secondary battery when a gasket between a battery can and the cap assembly and/or an insulating layer between a safety vent and a cap-down is dissolved or lost upon abnormal operation of the secondary battery so that the battery can is brought into close contact with the cap assembly and/or the safety vent is brought into close contact with the cap-down and a secondary battery including the cap assembly.
Secondary batteries are classified into cylindrical, prismatic, and pouch types depending on the shape of battery cases they employ. The cylindrical batteries include an electrode assembly accommodated in a cylindrical metal can. The prismatic batteries include an electrode assembly accommodated in a prismatic metal can. The pouch type batteries include an electrode assembly accommodated in a pouch type case made of an aluminum laminate sheet.
Electrode assemblies accommodated in battery cases are power generating devices capable of repeated charge/discharge cycles that have a cathode/separator/anode laminate structure. Electrode assemblies are classified into jelly-roll and stack types by their structure. The jelly-roll type structure is constructed by interposing a separator between an anode and a cathode, each of which is in the form of a long sheet coated with an active material, and winding the laminate in a roll form. The stack type structure is constructed by sequentially stacking a plurality of electrode units, each of which includes a cathode having a predetermined size, an anode having a predetermined size, and a separator interposed therebetween. The jelly-roll type electrode assemblies are most widely used in secondary batteries due to their ease of construction and high energy density per unit weight. The jelly-roll type electrode assemblies are usually employed in cylindrical batteries.
Secondary batteries employing jelly-roll type electrode assemblies are likely to deform because the jelly-roll type electrode assemblies undergo repeated swelling and shrinkage during charge/discharge. This deformation may cause internal short-circuiting.
Heat generated by internal short-circuiting decomposes organic solvents to produce gases. The gases increase the internal gas pressure of batteries to burst the batteries. An increase in the internal gas pressure of batteries may take place also when internal short-circuiting is caused by an external impact.
Many attempts have been made to solve the safety problems of batteries. For example, known is a cap assembly for a cylindrical battery having a structure in which a safety vent, safety devices, and a top cap are fixed by a gasket. High-pressure gases are released through the safety vent. The safety devices include a current interrupt device (CID) adapted to interrupt the flow of electric current when the internal pressure of the battery increases. The top cap forms a protruding terminal adapted to protect the safety devices.
In the structure of the cap assembly, the gasket surrounds the outer circumferences of the safety vent, the PTC device, the CID, the top cap, etc. to essentially prevent an electrolyte from leaking out from the battery. So long as the electrolyte is prevented from leaking through the interface between the innermost safety vent of the battery and the gasket surrounding the outer circumference of the safety vent, there is no leakage of the electrolyte through the interfaces between the metal parts, such as the interface between the safety vent and the PTC device and the interface between the PCT device and the top cap.
However, a portion of the electrolyte leaks substantially through the interface between the gasket and the safety vent during charge/discharge of the battery, when the battery falls down or when an external impact is applied to the battery. The leaking electrolyte easily escapes from the battery through the interfaces between the metal parts. That is, due to relatively weak adhesiveness at the interfaces between the metal parts, the electrolyte entering the interfaces between the metal parts easily leaks out of the cap assembly through the interfaces between the metal parts compared to through the interfaces between the gasket and the related devices.
Further, the electrolyte may be evaporated by heat generated upon abnormal operation in the can of the secondary battery. Thus, there is a strong need to develop a technique for reducing the leakage of electrolytes or their gases out of cap assemblies.
In this connection, Korean Patent Publication No. 2012-103394 discloses a secondary battery including an electrode assembly 10, a can 20 accommodating the electrode assembly 10, a cap assembly 30 sealing the can 20, a lower insulating plate 40, an upper insulating plate 50, a center pin 60, and an insulating gasket 70, as illustrated in Figs. 16 and 17. The insulating gasket 70 is positioned between the can 20 and the cap assembly 30 having opposite polarities. The insulating gasket 70 together with the cap assembly 30 seals the can 20 while insulating the can 20 from the cap assembly 30. The cap assembly 30 is fitted into the insulating gasket 70. The cap assembly 30 includes a top cap 31 acting as an electrode terminal, a vent 32, an insulator 33, a current interrupt device 34, and a sub-plate 35. The vent 32, the insulator 33, the current interrupt device 34, and the sub-plate 35 are positioned in this order on the top cap 31. The current interrupt device 34 is positioned on the electrode assembly. The current interrupt device 34 is electrically connected to a first electrode tab of the electrode assembly through the sub-plate 35, which is interposed between the current interrupt device and the first electrode tab. The current interrupt device 34 functions to interrupt the flow of electric current upon abnormal operation of the battery. The vent 32 is positioned on and in electrical contact with the current interrupt device 34. The vent 32 ruptures when the internal pressure of the can is increased by gases produced in the electrode assembly. That is, the vent 32 functions to decrease the internal pressure of the can. The vent 32 has a downwardly protruding portion 321 in contact with the current interrupt device 34 in the normal state of the battery. The protrusion 321 moves upward when the internal pressure of the can increases upon abnormal operation of the battery, and as a result, the vent 32 and the current interrupt device 34 are electrically opened to interrupt the flow of electric current. Although the vent 32 and the current interrupt device 34 are isolated from each other to interrupt the flow of electric current, the internal pressure of the can may continue to increase. In this case, the vent 32 ruptures such that the gases are released from the can to the outside, and as a result, the battery is free from any danger of explosion. The vent 32 is made of one or more material selected from aluminum, aluminum alloy, and shape memory alloys. The protrusion 321 is constructed such that it shrinks at a high temperature. Alternatively, the protrusion 321 may be constructed such that it protrudes downward at a normal temperature and protrudes upward at a predetermined temperature (e.g., 100 ℃). Due to this construction, the vent 32 and the current interrupt device 34 are electrically isolated from each other at the predetermined temperature so that the flow of electric current can be interrupted. The top cap 31 is electrically connected to a PTC thermistor 36 through a conductive adhesive 37, for example, a silver paste, or by soldering. This electrical connection allows the top cap 31 to act as an electrode terminal. However, the gasket surrounding the outer circumference of the cap assembly to seal the cap assembly may be melted or lost by heat generated in the secondary battery or an electrolyte. In this case, the cap assembly is changed in shape. As a result, as illustrated in Fig. 18, the gasket and an insulating layer interposed between metal parts (such as a cap-up, a safety vent, and a cap-down) as current-carrying members are corroded and lost by the leaking electrolyte or its gases and are physically attached to each other, causing electrical shorting.
The present invention has been made in view of the above problems, and it is a first object of the present invention to provide a cap assembly that prevents the occurrence of electrical shorting in a secondary battery when a gasket between a battery can and the cap assembly and/or an insulating layer between a safety vent and a cap-down is dissolved or lost upon abnormal operation of the secondary battery so that the battery can is brought into close contact with the cap assembly and/or the safety vent is brought into close contact with the cap-down. It is a second object of the present invention to provide a secondary battery including the cap assembly.
A first aspect of the present invention provides acapassemblyforpreventingelectricalshortinginasecondarybattery,includingacap-upattachedwithanelasticplateadaptedtointerrupttheflowofelectriccurrentbyinternalheatofthesecondarybattery,aCIDmoduleinterruptingtheflowofelectriccurrentbyinternalpressureofthesecondarybattery,andaninsulatingmemberinterposedbetweenthecap-upandtheCIDmodule.
According to one embodiment of the present invention, the cap-up may include a flange connected to a flat terminal through a portion extending obliquely from the terminal to form the rim of the terminal.
According to a further embodiment of the present invention, the insulating member may be interposed between the cap-up and an elastic support.
According to another embodiment of the present invention, the terminal may be fixed to and in electrical communication with one end of the elastic plate through a welding portion or a soldering portion.
According to another embodiment of the present invention, the other end of the elastic plate may be fixed to and in electrical communication with the elastic support through a welding portion or a soldering portion.
According to another embodiment of the present invention, each of the soldering portions may be formed by melting a soldering material and solidifying the molten soldering material and the soldering material may include bismuth.
According to another embodiment of the present invention, the bismuth may be present in an amount of 50 to 65% by weight, based on the total weight of the soldering material.
According to another embodiment of the present invention, the soldering material may have a melting point of 130 to 300 ℃.
According to another embodiment of the present invention, the soldering portion fixing the terminal to the one end of the elastic plate may be melted by heat generated in the secondary battery to allow the elastic plate to be restored downward.
According to another embodiment of the present invention, the soldering portion fixing the other end of the elastic plate to the elastic support may be melted by heat generated in the secondary battery to allow the elastic plate to be restored upward.
According to another embodiment of the present invention, the side of the flange opposite to the elastic plate may be perforated to form a through-hole adapted to prevent the elastic plate from interfering with the flange of the cap-up upon when the elastic plate is restored upward.
According to another embodiment of the present invention, the end portion of a safety vent of the CID module may be bent to surround the end portion of the elastic support.
According to another embodiment of the present invention, the terminal may further have an entrance hole through which a pressurizing member can reach the elastic plate.
According to another embodiment of the present invention, the elastic plate may have a central portion protruding toward the terminal.
According to another embodiment of the present invention, the central portion may be perforated with at least one slit for elasticity control.
According to another embodiment of the present invention, both ends of the elastic plate may be first and second welding portions where the flange is welded.
According to another embodiment of the present invention, the first and second welding portions may be formed by welding or diffusion-bonding.
According to another embodiment of the present invention, a current-carrying part may be interposed between the CID module and the central portion by pressurizing the central portion, melting a soldering material on the elastic plate, and solidifying the molten soldering material.
According to another embodiment of the present invention, the elastic plate may be made of copper or a copper alloy.
According to another embodiment of the present invention, the cap assembly may further include an attachment layer bonded to an area of the CID module facing the current-carrying part when the molten soldering material is solidified.
According to another embodiment of the present invention, the attachment layer may include nickel, a nickel alloy, tin, zinc, chromium, molybdenum, titanium or niobium.
According to another embodiment of the present invention, the soldering material may include bismuth.
According to another embodiment of the present invention, the soldering material may have a melting point of 130 to 300 ℃.
According to another embodiment of the present invention, the bismuth may be present in an amount of 50 to 65% by weight, based on the total weight of the soldering material.
According to another embodiment of the present invention, the CID module may include a safety vent having a central protrusion, a cap-down having a central opening portion arranged opposite to the protrusion, a second insulating member interposed between the safety vent and the cap-down such that the protrusion and the central portion are exposed, and a sub-plate fixed so as to cover the central portion and having a welding portion weld-attached to the protrusion.
According to another embodiment of the present invention, the CID module may include a safety vent having a central protrusion, a cap-down having a breakable portion in direct contact with the protrusion, and a second insulating member interposed between the safety vent and the cap-down such that the protrusion is exposed.
A second aspect of the present invention provides a secondary battery including the cap assembly.
According to the present invention, the cap assembly can prevent the occurrence of electrical shorting in a secondary battery when a gasket between a battery can and the cap assembly and/or an insulating layer between a safety vent and a cap-down is dissolved or lost upon abnormal operation of the secondary battery so that the battery can is brought into close contact with the cap assembly and/or the safety vent is brought into close contact with the cap-down.
Fig. 1 is a cross-sectional view illustrating one embodiment of a cap assembly of the present invention.
Fig. 2 is a bottom view illustrating a cap-up of a cap assembly according to the present invention in which a welding portion and a soldering portion are formed on a terminal and an elastic support, respectively.
Fig. 3 illustrates cross-sectional views explaining a process for manufacturing a cap assembly including (a) forming a soldering portion between an elastic plate and an elastic support, (b) assembling the elastic support and a cap-up by interposing an insulating member therebetween, (c) bonding a terminal to one end of the elastic plate, and (d) bending the end portion of a safety vent of a CID module to surround the end portion of the elastic support.
Fig. 4 illustrates a shape in which the other end of an elastic plate is restored upward when a soldering portion formed on an elastic support is melted by internal heat of a secondary battery.
Fig. 5 is a bottom view illustrating a cap-up of a cap assembly according to the present invention in which a soldering portion and a welding portion are formed on a terminal and an elastic support, respectively.
Fig. 6 illustrates a shape in which one end of an elastic plate is restored downward when a soldering portion formed on a terminal is melted by internal heat of a secondary battery.
Fig. 7 is a cross-sectional view illustrating a further embodiment of a cap assembly according to the present invention.
Fig. 8 is a cross-sectional view illustrating another embodiment of a cap assembly according to the present invention.
Fig. 9 is a plan view illustrating a cap-up and an elastic plate attached to the cap-up in a cap assembly of the present invention.
Fig. 10 illustrates a further embodiment of the elastic plate illustrated in Fig. 9.
Fig. 11 is a cross-sectional view of the cap-up illustrated in Fig. 9.
Fig. 12 is a cross-sectional view illustrating a shape in which a pressurizing member enters through an entrance hole of a cap-up to push an elastic plate and a shape in which a soldering material is applied to the elastic plate.
Fig. 13 is a cross-sectional view illustrating a shape in which an insulating member and a CID module are aligned with the pushed elastic plate illustrated in Fig. 12.
Fig. 14 is a cross-sectional view illustrating a shape in which a current-carrying part is formed by bonding the pushed elastic plate, the insulating member, and the CID module aligned in Fig. 13, dissolving the soldering material by heating, and solidifying the soldering material.
Fig. 15 illustrates cross-sectional views of a cap assembly according to the present invention: (a) a cross-sectional view of the cap assembly during normal operation of a secondary battery and (b) a cross-sectional view illustrating a shape in which a current-carrying part is melted by heat generated upon abnormal operation of the secondary battery and an elastic plate is restored by its elasticity to interrupt the flow of electric current.
Fig. 16 is an exploded perspective view of a conventional cylindrical secondary battery.
Fig. 17 is an exploded perspective view of an electrode assembly accommodated in a battery can of the secondary battery illustrated in Fig. 16.
Fig. 18 is a cross-sectional view illustrating a shape in which a gasket between a cap assembly and a battery can and/or an insulating layer between a safety vent and a cap-down is dissolved or lost to cause short-circuiting of a conventional secondary battery.
The present invention will now be described in more detail.
Technical terms used in this specification are used to merely illustrate specific embodiments, and should be understood that they are not intended to limit the present disclosure. As far as not being defined differently, all terms used herein including technical or scientific terms may have the same meaning as those generally understood by an ordinary person skilled in the art to which the present disclosure belongs to, and should not be construed in an excessively comprehensive meaning or an excessively restricted meaning.
In addition, if a technical term used in the description of the present disclosure is an erroneous term that fails to clearly express the idea of the present disclosure, it should be replaced by a technical term that can be properly understood by the skilled person in the art. In addition, general terms used in the description of the present disclosure should be construed according to definitions in dictionaries or according to its front or rear context, and should not be construed to have an excessively restrained meaning.
A singular representation may include a plural representation as far as it represents a definitely different meaning from the context. Terms "include" or "has" used herein should be understood that they are intended to indicate an existence of several components or several steps, disclosed in the specification, and it may also be understood that part of the components or steps may not be included or additional components or steps may further be included.
Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings where those components are rendered the same reference number that are the same or are in correspondence, regardless of the figure number, and redundant explanations are omitted.
Fig. 1 is a cross-sectional view illustrating one embodiment of a cap assembly of the present invention, Fig. 2 is a bottom view illustrating a cap-up of a cap assembly according to the present invention in which a welding portion and a soldering portion are formed on a terminal and an elastic support, respectively, Fig. 3 illustrates cross-sectional views explaining a process for manufacturing a cap assembly including (a) forming a soldering portion between an elastic plate and an elastic support, (b) assembling the elastic support and a cap-up by interposing an insulating member therebetween, (c) bonding a terminal to one end of the elastic plate, and (d) bending the end portion of a safety vent of a CID module to surround the end portion of the elastic support, Fig. 4 illustrates a shape in which the other end of an elastic plate is restored upward when a soldering portion formed on an elastic support is melted by internal heat of a secondary battery, Fig. 5 is a bottom view illustrating a cap-up of a cap assembly according to the present invention in which a soldering portion and a welding portion are formed on a terminal and an elastic support, respectively, Fig. 6 illustrates a shape in which one end of an elastic plate is restored downward when a soldering portion formed on a terminal is melted by internal heat of a secondary battery, Fig. 7 is a cross-sectional view illustrating a further embodiment of a cap assembly according to the present invention, Fig. 8 is a cross-sectional view illustrating another embodiment of a cap assembly according to the present invention, Fig. 9 is a plan view illustrating a cap-up and an elastic plate attached to the cap-up in a cap assembly of the present invention, Fig. 10 illustrates a further embodiment of the elastic plate illustrated in Fig. 9, Fig. 11 is a cross-sectional view of the cap-up illustrated in Fig. 9, Fig. 12 is a cross-sectional view illustrating a shape in which a pressurizing member enters through an entrance hole of a cap-up to push an elastic plate and a shape in which a soldering material is applied to the elastic plate, Fig. 13 is a cross-sectional view illustrating a shape in which an insulating member and a CID module are aligned with the pushed elastic plate illustrated in Fig. 12, Fig. 14 is a cross-sectional view illustrating a shape in which a current-carrying part is formed by bonding the pushed elastic plate, the insulating member, and the CID module aligned in Fig. 13, dissolving the soldering material by heating, and solidifying the soldering material, Fig. 15 illustrates cross-sectional views of a cap assembly according to the present invention: (a) a cross-sectional view of the cap assembly during normal operation of a secondary battery and (b) a cross-sectional view illustrating a shape in which a current-carrying part is melted by heat generated upon abnormal operation of the secondary battery and an elastic plate is restored by its elasticity to interrupt the flow of electric current, Fig. 16 is an exploded perspective view of a conventional cylindrical secondary battery, Fig. 17 is an exploded perspective view of an electrode assembly accommodated in a battery can of the secondary battery illustrated in Fig. 16, and Fig. 18 is a cross-sectional view illustrating a shape in which a gasket between a cap assembly and a battery can and/or an insulating layer between a safety vent and a cap-down is dissolved or lost to cause short-circuiting of a conventional secondary battery.
A cap assembly 100 of the present invention is designed to prevent electrical shorting in a secondary battery. The cap assembly 100 includes: a cap-up 300 attached with an elastic plate 200 adapted to interrupt the flow of electric current by internal heat of the secondary battery; a CID module 500 interrupting the flow of electric current by internal pressure of the secondary battery; and an insulating member 400 interposed between the cap-up and the CID module.
The elastic plate 200 is attached to the bottom of the cap-up 300 and acts as a terminal through which power generated in an electrode assembly is supplied to an external circuit or load. The flow of electric current through the elastic plate is interrupted by heat generated upon abnormal operation of the secondary battery.
This current interruption is achieved by the designs and operations of the cap-up and the elastic plate. First, the cap-up 300 includes a flange 320 connected to a flat terminal 310 through an extension 330 to form the rim of the terminal. Here, the extension 330 extends obliquely downward from the terminal and acts as an electrode terminal of the cap-up. The extension 330 may also have an air vent hole 340 as a space through which gases produced in the secondary battery are released to the outside.
The elastic plate 200 is a plate with elasticity that returns to its original shape when an external force is removed. The elastic plate 200 is a constituent element of the electric circuit of the secondary battery. When heat generated in the secondary battery is above a predetermined level, the elastic plate 200 returns to its original shape by its elasticity to interrupt the flow of electric current.
There is no particular restriction on the material for the elastic plate. Any suitable electric current-carrying material may be used for the elastic plate. For example, the elastic plate may be made of copper or a copper alloy.
As a specific example, one end 201 of the elastic plate 200 may be attached to the terminal 310 by laser welding, ultrasonic welding or soldering as to be in electrical communication with the terminal 310. A welding or diffusion-bonding method, such as ultrasonic welding, laser welding or resistance welding, is suitable for the formation of a welding portion WP that is maintained attached to the terminal 310 despite internal heat of the secondary battery. Alternatively, soldering is suitable for the formation of a soldering portion that is detached and electrically disconnected from the terminal 310 by internal heat of the secondary battery.
Specifically, the soldering portion may be formed by melting (or dissolving) a soldering material S by soldering and solidifying the molten soldering material at a low temperature.
The terms "melting" and "dissolution" are used interchangeably herein to mean that a solid is melted into a liquid or highly flowable fluid. For example, the terms may be used to express a phenomenon that the soldering material is melted.
The soldering material contains bismuth or includes zinc and a tin alloy. Preferably, the soldering material has a low melting point in the range of 130 to 300 ℃. Within this range, the insulating member 400 can be prevented from being melted or degraded during dissolution of the soldering material.
The soldering material may further contain an auxiliary metal, such as silver, and/or a flux for melting point control. The bismuth may be used in an amount of 50 to 65% by weight, based on the weight of the low-melting-point solder layer. If the bismuth is used in an amount of less than 50% by weight, the increased tin content may increase the melting point of the soldering material. Meanwhile, if the bismuth is used in an amount exceeding 65% by weight, the melting point of the soldering material may be reduced but the contact resistance may be difficult to control.
The other end 202 of the elastic plate can electrically connect the cap-up to the CID module 500 by welding or soldering an elastic support (ES). The elastic support (ES) and the cap-up are arranged to face each other through the insulating member 400.
That is, when one end 201 of the elastic plate is connected to the terminal 310 through a welding portion WP, the other end 202 of the elastic plate is connected to the elastic support through a soldering portion SP. Alternatively, when one end 201 of the elastic plate is connected to the terminal 310 through a soldering portion SP, the other end 202 of the elastic plate is connected to the elastic support through a welding portion WP.
The cap assembly of the present invention is distinguished in that when internal heat generated in the secondary battery upon abnormal operation of the secondary battery is applied to the cap-up 300 and the elastic support ES, the solder S of the soldering portion formed on the cap-up 300 or the elastic support ES is dissolved and the elastic plate 200 is restored by its elasticity to interrupt the flow of electric current. When the soldering portion formed on the elastic support is heated, the welding portion formed at the one end 201 of the elastic plate allows for upward elastic restoration (Pup)oftheelasticplate,andasaresult,theotherend202oftheelasticplateisdetachedfromtheelasticsupport.
In order for the other end of the elastic plate to pass through the flange 320 of the cap-up, a through-hole 322 is formed in the corresponding region of the flange opposite to the other end of the elastic plate such that the other end of the elastic plate is prevented from interfering with the flange when detached from the elastic support. In this case, the side of the insulating member opposite to the other end of the elastic plate is also exposed through the through-hole.
When the soldering portion formed on the terminal 310 of the cap-up is heated, the welding portion formed at the other end of the elastic plate allows for downward elastic restoration (Pdown)oftheelasticplate,andasaresult,theoneend201oftheelasticplateisdetachedfromtheelasticsupport.
The elastic plate 200 may be attached to the cap-up and the elastic support by welding or soldering the one end 201 and the other end 202 of the elastic plate 200 to the terminal and the elastic support, respectively. The order of the welding or soldering is arbitrary. Preferably, the welding or soldering is performed in such a manner that a welding portion or a soldering portion is formed on the elastic support and then a welding portion or a soldering portion is formed on the terminal of the cap-up.
Subsequently, the CID module 500 is attached to the bottom of the elastic support so as to be in electrical communication with the elastic support. Preferably, the CID module 500 includes a safety vent 510 having a central protrusion, a cap-down 530 having a central opening portion arranged opposite to the protrusion, a second insulating member 520 interposed between the safety vent and the cap-down portion such that the protrusion and the central portion are exposed, and a sub-plate 540 fixed so as to cover the central portion and having a welding portion weld-attached to the protrusion. According to the structure of the CID module 500, upon abnormal operation of the secondary battery, a high pressure generated in the secondary battery is applied to the safety vent 510 toward the outside to break the welding portion of the sub-plate, resulting in the interruption of electric current simultaneously with removal of the pressure.
The end portion of the safety vent 510 of the CID module may be bent to surround the end portion of the elastic support to improve the adhesion and sealing of the CID module to/against the elastic support ES. The cap-up 300 attached with the elastic plate 200 may be fastened to an opening of a battery can 20 of the secondary battery in a state in which the cap-up and the CID module are assembled together through the insulating member 400.
According to a further embodiment of the present invention, the CID module 500 may include a safety vent 510 having a central protrusion, a cap-down 530 having a breakable portion in direct contact with the protrusion, and a second insulating member 520 interposed between the safety vent and the cap-down such that the protrusion is exposed. That is, the CID module 500 has a structure in which the sub-plate is removed such that the safety vent is in direct electrical communication with the cap-down. According to the structure of the CID module 500, upon abnormal operation of the secondary battery, a high pressure generated in the secondary battery is applied to the safety vent 510 toward the outside to cut notches formed in the breakable portion, resulting in the interruption of electric current simultaneously with removal of the pressure.
As explained in the Background Art, the secondary battery is fabricated by assembling the cap assembly 100 with an electrode assembly 10, a can 20 accommodating the electrode assembly 10, a lower insulating plate 40 sealing the can 20, an upper insulating plate 50, a center pin 60, and an insulating gasket 70.
According to a further embodiment of the present invention, the terminal 310 of the cap-up may have an entrance hole 350. The entrance hole 350 is a space through which a pressurizing member 800 can reach the elastic plate 200, which will be described below. The entrance hole 350 is preferably positioned at the center of the terminal. This position is effective in interrupting the flow of electric current through the elastic plate when a current-carrying part 600 is heated, which will be described below.
The elastic plate has a central portion 210 protruding toward the terminal. A slope 220 is formed along the extension 330 to form the rim of the central portion. First and second welding portions 230 and 230' are attached to the flange 320 and extend from the slope.
Any suitable method may be used to attach the first and second welding portions 230 and 230' to the flange 320 so long as the flow of electric current can be ensured. Preferably, the first and second welding portions 230 and 230' are attached to the flange 320 by welding or diffusion-bonding. Examples of suitable welding methods include ultrasonic welding, laser welding, and resistance welding.
Here, at least one slit SL for elasticity control may be arranged in the central portion 210 or the slope 220. The arrangement of the slit facilitates controls over the interruption of electric current from the beginning of dissolution of a soldering material S till complete dissolution is reached, which will be explained below.
The slit SL may be present only in the inner surface of the central portion or the slope. Alternatively, the slit may penetrate through the inner surface of the central portion or the slope and may extend to the opposite end of the central portion or the slope (see Fig. 10). In this case, precise interruption of electric current can be achieved.
There is no particular restriction on the material for the elastic plate. Any suitable electric current-carrying material may be used for the elastic plate. For example, the elastic plate may be made of copper or a copper alloy.
As described above, the cap-up 300 attached with the elastic plate 200 may be fastened to an opening of the battery can 20 of the secondary battery in a state in which the cap-up and the CID module are assembled together through the insulating member.
Here, the insulating member is interposed and insulates between the cap-up and the CID module. In order to ensure the flow of electric current to the cap-up 300 as an electrode terminal, a portion of the central portion 210 is pressurized, and as a result, it comes into contact with the safety vent 510 of the CID module 500. At this time, a soldering material is arranged and dissolved between the central portion 210 and the safety vent 510. Then, the soldering material is solidified at a low temperature to form a melt-bonded current-carrying part 600.
The terms "melting" and "dissolution" are used interchangeably herein to mean that a solid is melted into a liquid or highly flowable fluid. For example, the terms may be used to express a phenomenon that the soldering material is melted.
The soldering material for the current-carrying part 600 contains bismuth or includes zinc and a tin alloy. Preferably, the soldering material has a low melting point in the range of 130 to 300 ℃. Within this range, the insulating member 400 can be prevented from being melted or degraded during dissolution of the soldering material.
The soldering material may further contain an auxiliary metal, such as silver, and/or a flux for melting point control. The bismuth may be used in an amount of 50 to 65% by weight, based on the weight of the low-melting-point solder layer. If the bismuth is used in an amount of less than 50% by weight, the increased tin content may increase the melting point of the soldering material. Meanwhile, if the bismuth is used in an amount exceeding 65% by weight, the melting point of the soldering material may be reduced but the contact resistance may be difficult to control.
To prevent an increase in contact resistance over time at the interface where the soldering material is attached, it is necessary to increase the wetting of the soldering material with the safety vent 510. Thus, the cap assembly may further include an attachment layer 700 bonded to an area of the CID module facing the current-carrying part 600 where the molten soldering material is solidified. The attachment layer may be formed using nickel, a nickel alloy, tin, zinc, chromium, molybdenum, titanium or niobium, which can be coated by physical vapor deposition, chemical vapor deposition or plating.
According to one embodiment of the present invention, the CID module 500 may include a safety vent 510 having a central protrusion, a cap-down 530 having a central opening portion arranged opposite to the protrusion, a second insulating member 520 interposed between the safety vent and the cap-down portion such that the protrusion and the central portion are exposed, and a sub-plate 540 fixed so as to cover the central portion and having a welding portion weld-attached to the protrusion. According to the structure of the CID module 500, upon abnormal operation of the secondary battery, a high pressure generated in the secondary battery is applied to the safety vent 510 toward the outside to break the welding portion of the sub-plate, resulting in the interruption of electric current simultaneously with removal of the pressure.
According to a further embodiment of the present invention, the CID module 500 may include a safety vent 510 having a central protrusion, a cap-down 530 having a breakable portion in direct contact with the protrusion, and a second insulating member 520 interposed between the safety vent and the cap-down such that the protrusion is exposed. That is, the CID module 500 has a structure in which the sub-plate is removed such that the safety vent is in direct electrical communication with the cap-down. According to the structure of the CID module 500, upon abnormal operation of the secondary battery, a high pressure generated in the secondary battery is applied to the safety vent 510 toward the outside to cut notches formed in the breakable portion, resulting in the interruption of electric current simultaneously with removal of the pressure.
As explained in the Background Art, the secondary battery is fabricated by assembling the cap assembly 100 with an electrode assembly 10, a can 20 accommodating the electrode assembly 10, a lower insulating plate 40 sealing the can 20, an upper insulating plate 50, a center pin 60, and an insulating gasket 70.
An explanation will be given concerning a method of manufacturing the cap assembly for preventing electrical shorting in a secondary battery according to the present invention. In describing the method of the present invention, repeated explanation of the elements and their connections explained in the cap assembly is omitted.
The method of the present invention includes aligning an elastic plate adapted to interrupt the flow of electric current by internal heat of the secondary battery with a cap-up to form first and second welding portions (step S1), inserting a pressurizing member through an entrance hole to press the elastic plate and loading a soldering material on the elastic plate (step S2), and aligning a CID module and an insulating member with the elastic plate and dissolving the soldering material by heating to form a current-carrying part (step S3).
Referring first to step S1, an elastic plate adapted to interrupt the flow of electric current by internal heat of the secondary battery is aligned with a cap-up to form first 230 and second welding portions 230'. The cap-up 300 includes a terminal 310, an extension 330, and a flange 320. The elastic plate 200 includes a central portion 210 and a slope 220.
Examples of methods for forming the first and second welding portions include, but are not necessarily limited to, laser welding, resistance welding, friction welding, and ultrasonic welding by which the first and second welding portions can be dissolved and welded.
For laser welding, it is beneficial in forming the first and second welding portions to irradiate a laser beam onto the elastic plate made of copper or a copper alloy rather than onto the cap-up.
Referring next to step S2, a pressurizing member is inserted through an entrance hole to press the elastic plate and a soldering material is loaded on the elastic plate. As explained earlier, the cap-up 300 includes a flat terminal 310, an extension 330, and a flange 320. The entrance hole is a space through which the pressurizing member 800 can reach the elastic plate 200 and may be positioned at the center of the terminal.
The pressurizing member 800 reaching the elastic plate 200 through the entrance hole 350 pressurizes the central portion 210 toward the terminal and moves the central portion to a position where the CID module can be reached. Thereafter, a soldering material S is applied to the central portion. The soldering material is the same as that described above and its explanation is omitted herein.
Referring next to step S3, a CID module and an insulating member are aligned with the cap-up welded to the elastic plate and the soldering material is dissolved by heating to form a current-carrying part. First, a CID module 500 is arranged opposite to the elastic plate 200. Then, an insulating member 400 is aligned such that it is interposed between the CID module and the elastic plate. The CID module 500 and the elastic plate 200 are brought into intimate contact with the insulating member 400. Thereafter, the CID module is heated to dissolve the soldering material S. The dissolved soldering material is solidified (by removing the heating element) to form a current-carrying part 600.
After solidification, the pressurizing member 800 is pulled back to manufacture the cap assembly of the present invention.
<Explanation of Reference Numerals>
100: Cap assembly 200: Elastic plate
210: Central portion of the elastic plate 220: Slope
230, 230': First and second welding portions 300: Cap-up
310: Terminal 320: Flange
330: Extension 340: Air vent hole
350: Entrance hole 400: Insulating member
500: CID module 600: Current-carrying part
700: Attachment layer 800: Pressurizing member
SL: Slit S: Soldering material

Claims (27)

  1. A cap assembly for preventing electrical shorting in a secondary battery, comprising a cap-up attached with an elastic plate adapted to interrupt the flow of electric current by internal heat of the secondary battery, a CID module interrupting the flow of electric current by internal pressure of the secondary battery, and an insulating member interposed between the cap-up and the CID module.
  2. The cap assembly according to claim 1, wherein the cap-up comprises a flange connected to a flat terminal through a portion extending obliquely from the terminal to form the rim of the terminal.
  3. The cap assembly according to claim 1, wherein the insulating member is interposed between the cap-up and an elastic support.
  4. The cap assembly according to claim 2, wherein the terminal is fixed to and in electrical communication with one end of the elastic plate through a welding portion or a soldering portion.
  5. The cap assembly according to claim 4, wherein the other end of the elastic plate is fixed to and in electrical communication with the elastic support through a welding portion or a soldering portion.
  6. The cap assembly according to claim 4 or 5, wherein the soldering portion is formed by melting a soldering material and solidifying the molten soldering material and the soldering material comprises bismuth.
  7. The cap assembly according to claim 6, wherein the bismuth is present in an amount of 50 to 65% by weight, based on the total weight of the soldering material.
  8. The cap assembly according to claim 6, wherein the soldering material has a melting point of 130 to 300 ℃.
  9. The cap assembly according to claim 4, wherein the soldering portion is melted by heat generated in the secondary battery to allow the elastic plate to be restored downward.
  10. The cap assembly according to claim 5, wherein the soldering portion is melted by heat generated in the secondary battery to allow the elastic plate to be restored upward.
  11. The cap assembly according to claim 10, wherein the side of the flange opposite to the elastic plate is perforated to form a through-hole adapted to prevent the elastic plate from interfering with the flange of the cap-up upon when the elastic plate is restored upward.
  12. The cap assembly according to claim 3, wherein the end portion of a safety vent of the CID module is bent to surround the end portion of the elastic support.
  13. The cap assembly according to claim 2, wherein the terminal further has an entrance hole through which a pressurizing member reaches the elastic plate.
  14. The cap assembly according to claim 13, wherein the elastic plate has a central portion protruding toward the terminal.
  15. The cap assembly according to claim 14, wherein the central portion is perforated with at least one slit for elasticity control.
  16. The cap assembly according to claim 1, wherein both ends of the elastic plate are first and second welding portions where the flange is welded.
  17. The cap assembly according to claim 16, wherein the first and second welding portions are formed by welding or diffusion-bonding.
  18. The cap assembly according to claim 14, wherein a current-carrying part is interposed between the CID module and the central portion by pressurizing the central portion, melting a soldering material on the elastic plate, and solidifying the molten soldering material.
  19. The cap assembly according to claim 1, wherein the elastic plate is made of copper or a copper alloy.
  20. The cap assembly according to claim 1, wherein the cap assembly further comprises an attachment layer bonded to an area of the CID module facing the current-carrying part when the molten soldering material is solidified.
  21. The cap assembly according to claim 20, wherein the attachment layer comprises nickel, a nickel alloy, tin, zinc, chromium, molybdenum, titanium or niobium.
  22. The cap assembly according to claim 18, wherein the soldering material comprises bismuth.
  23. The cap assembly according to claim 22, wherein the bismuth is present in an amount of 50 to 65% by weight, based on the total weight of the soldering material.
  24. The cap assembly according to claim 18, wherein the soldering material has a melting point of 130 to 300 ℃.
  25. The cap assembly according to claim 1, wherein the CID module comprises a safety vent having a central protrusion, a cap-down having a central opening portion arranged opposite to the protrusion, a second insulating member interposed between the safety vent and the cap-down such that the protrusion and the central portion are exposed, and a sub-plate fixed so as to cover the central portion and having a welding portion weld-attached to the protrusion.
  26. The cap assembly according to claim 1, wherein the CID module comprises a safety vent having a central protrusion, a cap-down having a breakable portion in direct contact with the protrusion, and a second insulating member interposed between the safety vent and the cap-down such that the protrusion is exposed.
  27. A secondary battery comprising the cap assembly according to any one of claims 1 to 26.
PCT/KR2017/008082 2016-08-11 2017-07-27 Cap assembly for preventing electrical shorting and secondary battery including the same WO2018030679A1 (en)

Applications Claiming Priority (6)

Application Number Priority Date Filing Date Title
KR20160102222 2016-08-11
KR10-2016-0102222 2016-08-11
KR20170019972 2017-02-14
KR10-2017-0019972 2017-02-14
KR1020170047404A KR20180018279A (en) 2016-08-11 2017-04-12 Cap assembly of excellent electrical safety for a secondary battery and the battery inclusive of the same
KR10-2017-0047404 2017-04-12

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WO2018030679A1 true WO2018030679A1 (en) 2018-02-15

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EP3518309A4 (en) * 2017-08-14 2020-01-15 LG Chem, Ltd. Pressurization mask and method for connecting top cap assembly and electrode tab by using pressurization mask
CN110890483A (en) * 2019-11-29 2020-03-17 安徽江淮汽车集团股份有限公司 Cylinder battery with novel structure
CN111312939A (en) * 2020-03-27 2020-06-19 江苏芯界新能源科技有限公司 Battery end cover with safety protection function

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EP3518309A4 (en) * 2017-08-14 2020-01-15 LG Chem, Ltd. Pressurization mask and method for connecting top cap assembly and electrode tab by using pressurization mask
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CN111312939A (en) * 2020-03-27 2020-06-19 江苏芯界新能源科技有限公司 Battery end cover with safety protection function

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