KR101335285B1 - Cap Assembly of Novel Structure and Cylindrical Battery Employed with the Same - Google Patents

Abstract

The present invention provides a cap assembly mounted on an open upper end of a can in a battery having a structure in which an electrode assembly (jelly-roll) having a positive electrode / membrane / cathode structure is embedded in a cylindrical can, and has a predetermined notch to be ruptured by the high pressure gas of the battery. The safety vent is formed; A protruding top cap connected to the safety vent along the outer circumferential surface thereof; A gasket mounted on an outer circumferential surface of the upper cap; And a fire extinguishing component for preventing ignition of the battery, wherein at least a portion of the fire extinguishing member is mounted at an interface between the top cap and the gasket; It provides a cap assembly comprising a.

Description

Cap Assembly of Novel Structure and Cylindrical Battery Employed with the Same}

The present invention relates to a cap assembly having a novel structure, and more particularly, an electrode assembly (jelly-roll) of the anode / separator / cathode structure is mounted in the open upper end of the can in a battery having a structure in which the cylindrical can is embedded. A cap assembly, comprising: a safety vent having a predetermined notch formed to be ruptured by a high pressure gas of a battery; A protruding top cap connected to the safety vent along the outer circumferential surface thereof; A gasket mounted on an outer circumferential surface of the upper cap; And a fire extinguishing component for preventing ignition of the battery, wherein at least a portion of the fire extinguishing member is mounted at an interface between the top cap and the gasket.

As technology development and demand for mobile devices have increased, the demand for secondary batteries as energy sources has been rapidly increasing. Many researches have been conducted on lithium secondary batteries with high energy density and discharge voltage among such secondary batteries. .

The secondary battery is classified into a cylindrical battery and a prismatic battery in which the electrode assembly is housed in a cylindrical or rectangular metal can according to the shape of the battery case, and a pouch-shaped battery in which the electrode assembly is housed in a pouch-shaped case of an aluminum laminate sheet . Among them, the cylindrical battery has the advantage of relatively large capacity and structurally stable.

In addition, the electrode assembly embedded in the battery case is a power generator capable of charging and discharging composed of a laminated structure of a positive electrode, a separator, and a negative electrode, and a jelly-roll type wound around a separator between a long sheet type positive electrode and a negative electrode coated with an active material; A plurality of positive and negative electrodes of a predetermined size are classified into a stack type in which a plurality of positive and negative electrodes are sequentially stacked in a state where a separator is interposed therebetween. Among them, the jelly-roll type electrode assembly has an advantage of being easy to manufacture and having a high energy density per weight.

1 is a vertical cross-sectional perspective view of a typical cylindrical battery.

Referring to FIG. 1, the cylindrical battery 100 receives a jelly-roll type (wound) electrode assembly 120 in a cylindrical case 130 and injects an electrolyte solution into the cylindrical case 130, and then the case 130. The top cap 140 is formed by coupling an electrode terminal (for example, a positive electrode terminal; not shown) to an open upper end of the cap.

The jelly-roll type electrode assembly 120 has a structure in which a cathode 121, a cathode 122, and a separator 123 are stacked in turn to be wound in a round shape, and a center of the cylinder is formed at the center of the core assembly 120. The pin 150 is inserted. The center pin 150 is generally made of a metal material to give a predetermined strength and is formed of a hollow cylindrical structure in which a plate material is bent in a round shape. The center pin 150 serves as a passage for fixing and supporting the electrode assembly 120 and for releasing gas generated by internal reactions during charging and discharging and during operation.

On the other hand, the lithium secondary battery has a disadvantage of low safety. For example, when the battery is overcharged to about 4.5 V or more, decomposition reaction of the positive electrode active material occurs, dendrite growth of lithium metal at the negative electrode, decomposition reaction of electrolyte solution, and the like occur.

In this process, the decomposition reaction and the many side reactions are rapidly proceeded with heat accompanied by heat, and the ignition and explosion of the battery may be caused.

Therefore, in order to solve this problem, the general cylindrical secondary battery has a current interrupting member (CID) to cut off the current during abnormal operation of the battery and to break the breakdown voltage (CID) space between the jelly-roll type electrode assembly and the top cap It is mounted on.

Referring to FIG. 2, the top cap 10 has a positive electrode terminal formed in a protruding shape, and an exhaust port is perforated, and a PTC element for blocking current by greatly increasing battery resistance when the temperature inside the battery rises at the bottom thereof ( Positive temperature coefficient element: 20), in the normal state has a downwardly protruding shape, the safety vent 30 to explode and exhaust gas when the pressure inside the battery rises, and the upper one side is coupled to the safety vent 30 The connection plate 50, which is connected to the anode of the electrode assembly 40, is positioned sequentially.

Therefore, under normal operating conditions, the anode of the electrode assembly 40 is connected to the top cap 10 through the lead 42, the connection plate 50, the safety vent 30, and the PTC element 20 to conduct electricity. .

However, if a problem occurs in some safety devices such as the safety vent 30 or the PTC device 20, there is still a risk that the battery will ignite.

That is, the lithium secondary battery has a high risk of ignition when placed in various environments such as overcharging, external heating, and physical deformation. Various methods have been proposed to prevent overcharge, which is the cause of the ignition hazard, and to prevent internal short-circuit due to physical deformation. However, despite these preventive measures, measures are required to prevent ignition, or at least to inhibit its progress when ignition is initiated. The risk of ignition is particularly serious in large capacity batteries.

Therefore, there is a high need for a technique capable of fundamentally solving such problems.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-described problems of the prior art and the technical problems required from the past.

It is an object of the present invention to provide a cap assembly capable of preventing ignition of a battery cell by a fire extinguishing member comprising a fire extinguishing component.

It is still another object of the present invention to provide a cylindrical battery with improved safety, including such a cap assembly.

Accordingly, the cap assembly according to the present invention is a cap assembly mounted on an open top end of a can in a battery having a structure in which an electrode assembly (jelly-roll) having a cathode / separation membrane / cathode structure is embedded in a cylindrical can,

A safety vent having a predetermined notch formed to be ruptured by the high pressure gas of the battery;

A protruding top cap connected to the safety vent along the outer circumferential surface thereof;

A gasket mounted on an outer circumferential surface of the upper cap; And

A fire extinguishing member including a fire extinguishing component for preventing ignition of the battery, at least a part of which is mounted at an interface between the top cap and the gasket;

As shown in FIG.

In general, ignition of a battery cell occurs in the upper portion of the cell. Accordingly, the cap assembly according to the present invention can prevent the battery cell from being ignited by the fire extinguishing member by placing the fire extinguishing member at the interface between the upper cap and the gasket, thereby reacting more rapidly to temperature change. .

As such, the space in which the fire extinguishing member which suppresses the ignition of the battery cell can be mounted is very limited in consideration of the overall structure of the battery. According to the present invention, at least a part of the fire extinguishing member is mounted at the interface between the upper cap and the gasket. It takes a structure to become.

In one preferred example, the interface on which at least a portion of the fire extinguishing member is mounted may be the top surface or outer peripheral side of the top cap.

Preferably, so that the fire extinguishing member can correspond to the shape of the interface of the top cap or gasket, it is preferably made of a planar hollow annular structure, the outer portion of the size of 20 to 100% in the radius of the top cap It may be a structure that is fixed to the interface of the gasket.

The fire extinguishing member is not particularly limited as long as it can exert an excellent fire suppression function without degrading the performance of the battery. For example, the fire extinguishing member may be a metal ring or a hollow hollow flame retardant film having a flame retardant component. have.

The kind of the flame retardant component (“frame retardant”) is not particularly limited, and for example, halogen-based flame retardants, phosphorus-based flame retardants, inorganic compound flame retardants, and the like may be used, and in some cases, one or more of them. It can also be used in the form of a mixture.

The halogen-based flame retardant generally exhibits a flame retarding effect by substantially stabilizing the radicals generated on the gas phase. Examples of halogen-based flame retardants include tribromo phenoxyethane, tetra bromo bisphenol-A (TBBA), octabromo diphenyl ether (OBDPE), brominated epoxy, brominated polycarbonate oligomo, chlorinated paraffin, chlorinated polyethylene, alicyclic Chlorine-based flame retardants and the like.

Phosphorus-based flame retardants generally produce a polymethic acid by pyrolysis, and the carbon film produced by dehydration when it forms a protective layer or when polymethic acid is produced exerts a flame retardant effect. Examples of phosphorus-based flame retardants include phosphates such as red, ammonium phosphate, phosphine oxide, phosphine oxide diols, phosphites, phosphonates, triaryl phosphate, alkyldiaryl phosphate, trialkyl phosphate, resorcinaol bisdiphenyl phosphate (RDP), and the like.

The inorganic compound flame retardant is generally decomposed by heat to release an incombustible gas such as water, carbon dioxide, sulfur dioxide, and hydrogen chloride to induce an endothermic reaction, thereby preventing the access of oxygen by diluting the flammable gas and cooling and pyrolysis The production of the product is reduced and the flame retarding effect is exhibited. Examples of such inorganic compound flame retardants include aluminum hydroxide, magnesium hydroxide, antimony oxide, tin hydroxide, tin oxide, molybdenum oxide, zirconium compounds, borate salts, calcium salts, and the like.

Specifically, the flame retardant component may be one containing a halon component. Halon is a carbon compound gas of halogen element (fluorine (fluorine), chlorine, bromine vapor). By blocking the oxidation reaction of the combustion product by the cocatalyst of halogen element, it prevents the access of oxygen and prevents combustion. As an example of such a halon, Halon-1211 (Halon-1211: CF2BrCl) can be preferably used.

The substrate of the flame retardant film is not particularly limited as long as the substrate can stably hold the flame retardant without causing chemical reaction inside the battery. Examples of such film substrates include polyethylene, polypropylene, polyurethane, or fluorine-based polymers. Polyurethanes and the like, which preferably exhibit flame retardancy per se, may be used.

In one specific example, the flame retardant component is preferably included in 20 to 90% by weight based on the total weight of the flame retardant film. The flame retardant may be present in the form contained within the film substrate, and in some cases, may be present in the form of a coating on the outer surface of the film.

In another specific example, the flame retardant component may be included in the ring substrate in an amount of 20 to 90 wt% based on the total weight of the metal ring.

On the other hand, the extinguishing member may have a characteristic of absorbing heat by changing from a liquid to a gas at a predetermined temperature or more. That is, when the internal temperature of the battery cell continuously rises and reaches a predetermined temperature before the time of explosion, the fire can be effectively prevented by absorbing the surrounding heat by the extinguishing member and blocking the surrounding air to further increase the temperature. You can prevent it.

The predetermined temperature may be, for example, 100 ° C or higher, and preferably, may be determined in the range of 100 ° C to 200 ° C.

In one example, the safety vent has a shape in which the center is indented downward, and the first notch and the second notch are formed in the upper bent portion and the lower bent portion forming the indentation, respectively, the first notch Comprising a closed curve, the second notch formed in the lower portion has a structure of the open curve on one side, the second notch may be a structure that is deeper than the first notch.

Thus, the second notch is formed deeper than the first notch, so that when the pressurized gas above the critical pressure presses the safety vent, the second notch is cut. On the other hand, the first notch acts together with the second notch when the pressurized gas below the second critical pressure acts on the safety vent, so that the recess can be lifted up.

In another example, a PTC device may be interposed between the upper cap and the safety vent.

That is, since the PTC element is interposed in the adjacent position of the fire extinguishing member, when the PTC element does not operate at a predetermined temperature or more, the fire extinguishing member immediately absorbs heat, thereby ensuring the safety of the battery cell.

The present invention also provides a cylindrical cell consisting of including the cap assembly.

In the cylindrical secondary battery according to the present invention, in the state in which the jelly-roll type electrode assembly is mounted on a cylindrical metal can, the cap assembly is coupled to the open top of the metal can, and the negative electrode of the electrode assembly is welded to the bottom of the can, It is manufactured by welding the positive electrode of the electrode assembly to the cap assembly coupled to the top of the electrode assembly and the electrolyte in order to seal the battery in the built-in state.

The battery according to the present invention may preferably be a lithium secondary battery having high energy density, discharge voltage, and output stability. Other components of the lithium secondary battery according to the present invention will be described in detail below.

Generally, a lithium secondary battery is composed of a positive electrode, a negative electrode, a separator, a non-aqueous electrolyte containing a lithium salt, and the like.

The positive electrode is prepared, for example, by applying a mixture of a positive electrode active material, a conductive material and a binder on a positive electrode current collector, followed by drying, and if necessary, a filler is further added. The negative electrode is also manufactured by applying and drying the negative electrode material on the negative electrode collector, and if necessary, may further include the above-described components.

The separation membrane is interposed between the cathode and the anode, and an insulating thin film having high ion permeability and mechanical strength is used.

The lithium salt-containing non-aqueous electrolyte solution consists of a non-aqueous electrolyte solution and a lithium salt. As the non-aqueous electrolyte solution, a liquid nonaqueous electrolyte solution, a solid electrolyte, an inorganic solid pregelatin, and the like are used.

The collector, the electrode active material, the conductive material, the binder, the filler, the separator, the electrolyte, and the lithium salt are well known in the art, and a detailed description thereof will be omitted herein.

The lithium secondary battery according to the present invention can be manufactured by a conventional method known in the art. That is, a porous separator may be inserted between the anode and the cathode, and an electrolyte may be injected into the separator.

The anode can be produced, for example, by applying a slurry containing the above-described lithium transition metal oxide active material, a conductive material and a binder on a current collector, followed by drying. Likewise, the negative electrode can be produced, for example, by applying a slurry containing the above-described carbon active material, a conductive material and a binder onto a thin current collector and then drying it.

As described above, the cap assembly according to the present invention is equipped with a fire extinguishing member including a fire extinguishing component at the interface between the top cap and the gasket, thereby preventing the ignition of the battery to improve the safety.

1 is a vertical sectional perspective view of a typical cylindrical battery;
2 is a partial cross-sectional perspective view of FIG. 1.
3 is a perspective view of a cylindrical battery according to one embodiment of the present invention;
4 is an exploded view of FIG. 3;
5 is a partially enlarged view of FIG. 3;
6 is a partial cross-sectional perspective view of FIG. 3;
7 is a perspective view of the safety vent of FIG. 6.

Hereinafter, the present invention will be described in detail with reference to the drawings, but the scope of the present invention is not limited thereto.

Figure 3 is a schematic view of a perspective view of a cylindrical battery according to an embodiment of the present invention, Figure 4 is an exploded view of Figure 3 is shown.

Referring to these drawings, the cylindrical battery 100a according to the present invention inserts a jelly-roll (not shown) into the inside of the can 200, injects an electrolyte therein, and opens the open top of the can 200. Mount the cap assembly 300. In addition, after the insulating member 400 is seated on the cap assembly 300 to insulate the positive electrode and the negative electrode, the insulating member 400 is compressed by the tube 410 to maintain the insulating state.

FIG. 5 is a partially enlarged view of FIG. 3 and FIG. 6 is a partially enlarged view of FIG. 3.

3 and 4, the cap assembly 300 includes a safety vent 330 having a predetermined notch formed to be ruptured by the high pressure gas of the battery; A protruding top cap 310 connected to it along the outer circumferential surface of the safety vent 320; A gasket 340 mounted on an outer circumferential surface of the upper cap 310; A PTC element 350 interposed between the upper cap 310 and the safety vent 320; And a fire extinguishing member 360 mounted at an interface between the upper cap 310 and the gasket 340.

The fire extinguishing member 350 is formed in a planar hollow annular structure, and the outermost portion is radially fixed to the interface between the top cap 310 and the gasket 340.

In addition, the fire extinguishing member 350 is in the shape of a metal ring including a halon component, which is a flame retardant component, and the flame retardant component is included in the ring substrate in an amount of about 60 wt% based on the total weight of the metal ring. .

Accordingly, at 100 ° C. or higher, the fire extinguishing member 350 absorbs the surrounding heat and blocks the surrounding air to further suppress temperature rise. Therefore, it is possible to fundamentally prevent the ignition of the battery and to improve the safety of the battery.

FIG. 7 schematically illustrates a perspective view of the safety vent of FIG. 6.

The first notch 324 formed on the upper part of the notches 324 and 326 of the safety vent 320 forms a closed curve, and the second notch 326 formed on the lower part has a structure of an open curve having one side open. It is. In addition, since the engagement force of the second notch 326 is made smaller than the engagement force of the first notch 324, the second notch 326 is dug deeper than the first notch 324.

Accordingly, when the internal pressure of the can 200 rises above the critical pressure, the second notch 326 of the safety vent 320 does not withstand the pressure and breaks so that the pressurized gas in the can 200 escapes to the outside. do.

Those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Claims (17)

A cap assembly mounted on an open upper end of a can in a battery having a structure in which an electrode assembly (jelly-roll) having a cathode / membrane / cathode structure is embedded in a cylindrical can,
A safety vent having a predetermined notch formed to be ruptured by the high pressure gas of the battery;
A protruding top cap connected to the safety vent along the outer circumferential surface thereof;
A gasket mounted on an outer circumferential surface of the upper cap; And
A fire extinguishing member including a fire extinguishing component for preventing ignition of the battery, at least a part of which is mounted at an interface between the top cap and the gasket;
Lt; / RTI >
The fire extinguishing member is a hollow flame retardant film having a metal ring or a thin film shape containing a flame retardant component,
The flame retardant component is a cap assembly, characterized in that contained in the interior of the ring or film substrate in an amount of 20 to 90% by weight based on the total weight of the metal ring or flame retardant film. The cap assembly of claim 1, wherein an interface on which at least a portion of the fire extinguishing member is mounted is a top surface or an outer circumferential side of the top cap. 2. The cap as claimed in claim 1, wherein the extinguishing member has a hollow annular structure in plan view, and the outer portion having a radius of 20 to 100% is fixed to the interface between the upper cap and the gasket. assembly. delete The cap assembly of claim 1, wherein the flame retardant component is one or a mixture of two or more selected from the group consisting of a halogen flame retardant, a phosphorus flame retardant, and an inorganic compound flame retardant. 6. The cap assembly of claim 5 wherein said flame retardant component comprises a halon component. The cap assembly of claim 1, wherein the substrate of the flame retardant film is polyethylene, polypropylene, polyurethane, or fluorine-based polymer. delete delete The cap assembly of claim 1, wherein the extinguishing member has a property of absorbing heat by changing from a liquid to a gas at a predetermined temperature or more. 11. The cap assembly of claim 10 wherein said temperature is at least 100 < 0 > C. The safety vent of claim 1, wherein the safety vent has a shape in which the center is indented downward, and a first notch and a second notch are formed in an upper bent part and a lower bent part, respectively. The first notch forms a closed curve, and the second notch formed at the lower portion has a structure of an open curve at one side thereof, and the second notch is deeper than the first notch. . The cap assembly according to claim 1, wherein a PTC element is interposed between the upper cap and the safety vent. 14. A cylindrical battery comprising a cap assembly according to any one of claims 1 to 3, 5 to 7, and 10 to 13. The cylindrical battery according to claim 14, wherein the battery is a lithium secondary battery. A cap assembly mounted on an open upper end of a can in a battery having a structure in which an electrode assembly (jelly-roll) having a cathode / membrane / cathode structure is embedded in a cylindrical can,
A safety vent having a predetermined notch formed to be ruptured by the high pressure gas of the battery;
A protruding top cap connected to the safety vent along the outer circumferential surface thereof;
A gasket mounted on an outer circumferential surface of the upper cap; And
A fire extinguishing member including a fire extinguishing component for preventing ignition of the battery, at least a part of which is mounted at an interface between the top cap and the gasket;
Lt; / RTI >
The fire extinguishing member is a hollow flame retardant film having a metal ring or a thin film shape containing a flame retardant component,
The flame retardant component is a cap assembly, characterized in that one or two or more mixtures selected from the group consisting of halogen-based flame retardant, phosphorus-based flame retardant, and inorganic compound flame retardant. A cap assembly mounted on an open upper end of a can in a battery having a structure in which an electrode assembly (jelly-roll) having a cathode / membrane / cathode structure is embedded in a cylindrical can,
A safety vent having a predetermined notch formed to be ruptured by the high pressure gas of the battery;
A protruding top cap connected to the safety vent along the outer circumferential surface thereof;
A gasket mounted on an outer circumferential surface of the upper cap; And
A fire extinguishing member including a fire extinguishing component for preventing ignition of the battery, at least a part of which is mounted at an interface between the top cap and the gasket;
Lt; / RTI >
The fire extinguishing member has a cap assembly characterized in that it has a characteristic of absorbing heat by changing from a liquid to a gas at 100 ℃ or more.

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