JP2014517468A - Cap structure having novel structure and cylindrical battery having the same - Google Patents

Abstract

The present invention is a cap assembly mounted on the open upper end of a can in a battery having a structure in which a positive electrode / separation membrane / negative electrode structure (jelly roll) is built in a cylindrical can, A safety vent in which a predetermined notch is formed so as to be ruptured by the high-pressure gas of the battery, a projecting upper end cap connected to the outer periphery of the safety vent, and an outer peripheral surface of the upper end cap. And a fire extinguishing member containing a fire extinguishing component for preventing ignition of the battery and at least a part of which is sandwiched between the upper end cap and the gasket. Provide assembly.
[Selection] Figure 5

Description

  The present invention relates to a cap assembly having a novel structure. In particular, the present invention relates to a cap assembly mounted on an open upper end of a can in a battery having a structure in which a positive electrode / separation membrane / negative electrode assembly (jelly roll) is built in a cylindrical can. A safety vent in which a predetermined notch is formed so as to be ruptured by, a protruding upper end cap connected to the outer periphery of the safety vent, a gasket attached to the outer periphery of the upper end cap, and The present invention relates to a cap assembly comprising a fire extinguishing member that contains a fire extinguishing component for preventing ignition of a battery and at least a part of which is sandwiched between an interface between an upper end cap and a gasket.

  With the development of technology and demand for mobile devices, the demand for secondary batteries as an energy source has also increased rapidly. In particular, research on lithium secondary batteries with high energy density and discharge voltage has been actively conducted. Currently being commercialized and widely used.

  Depending on the shape of the battery case, the secondary battery has a cylindrical battery or square battery in which the electrode assembly is built in a cylindrical or square metal can, and an electrode assembly is built in a pouch-shaped case made of an aluminum laminate sheet. It is classified as a pouch-type battery. Among them, the cylindrical battery has an advantage that it has a relatively large capacity and is structurally stable.

  The electrode assembly built in the battery case is a chargeable / dischargeable power generating element having a positive electrode / separation membrane / negative electrode laminated structure, and is provided between a long sheet-like positive electrode coated with an active material and the negative electrode. It is classified into a jelly roll type wound up with a separation membrane and a stack type in which a large number of positive electrodes and negative electrodes having a predetermined size are sequentially stacked with the separation membrane interposed. Among them, the jelly-roll electrode assembly has advantages that it is easy to manufacture and has a high energy density per weight.

  FIG. 1 is a vertical sectional perspective view showing a general cylindrical battery.

  Referring to FIG. 1, a cylindrical battery 100 includes a jelly roll-type (winding-type) electrode assembly 120 accommodated in a cylindrical case 130, and an electrolyte is injected into the cylindrical case 130. A top cap 140 provided with an electrode terminal (for example, a positive electrode terminal (not shown)) is coupled to the opened upper end.

  The jelly-roll electrode assembly 120 has a structure in which a positive electrode 121, a negative electrode 122, and a separation membrane 123 are sequentially stacked and wound in a round shape, and a cylindrical shape is formed at the center of the electrode assembly 120 that is the winding core. A center pin 150 is inserted. The center pin 150 is mainly made of a metal material so as to have a predetermined strength, and has a hollow cylindrical structure in which a plate material is bent round. The center pin 150 functions to hold the electrode assembly 120 and to function as a passage for releasing a gas generated by an internal reaction during charge / discharge and operation.

  On the other hand, the lithium secondary battery has a drawback of low safety. For example, when the battery is overcharged to about 4.5 V or more, a decomposition reaction of the positive electrode active material occurs, a dendrite growth of lithium metal at the negative electrode, a decomposition reaction of the electrolyte, and the like occur. When heat is generated in such a process, the above decomposition reaction and a large number of side reactions proceed rapidly, and may eventually lead to ignition or explosion of the battery.

  In order to solve such a problem, a general cylindrical secondary battery has a current interrupting device (CID) for interrupting the current and eliminating the internal pressure when the battery operates abnormally. A space between the roll-type electrode assembly and the top cap is mounted.

  Referring to FIG. 2, the top cap 10 has a protruding shape that forms a positive electrode terminal, and an exhaust port is perforated. Also, below the top cap 10, a PTC element (positive temperature effective element) 20 that cuts off the current due to a large increase in battery resistance when the temperature inside the battery rises, has a shape protruding downward in a normal state, When the pressure inside the battery rises, the safety vent 30 that bursts upward and ruptures and exhausts gas is connected to the safety vent 30, and the lower end side is connected to the positive electrode of the electrode assembly 40. Connection plates 50 are arranged in order.

  Therefore, under normal operating conditions, the positive electrode 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, and is energized.

  However, there is still a risk that the battery will ignite if problems occur with some safety devices such as the safety vent 30 or the PTC element 20.

  That is, when the lithium secondary battery is placed in various environments such as overcharge, external heating, and physical deformation, the risk of ignition increases. Thus, various methods have been proposed for preventing overcharge, which is the cause of the risk of such ignition, and preventing internal short-circuits due to physical deformation. However, in spite of such preventive measures, there is a demand for means for preventing ignition or at least suppressing the progress of the ignition. The risk of ignition becomes more serious in large capacity batteries.

  Therefore, there is an urgent need for a technology that can fundamentally solve such problems.

  The object of the present invention is to solve the problems of the prior art as described above and the technical problems that have been requested from the past.

  The objective of this invention is providing the cap assembly which can prevent ignition of a battery cell by the fire extinguishing member containing a fire extinguishing component.

  Another object of the present invention is to provide a cylindrical battery having improved safety by providing the cap assembly.

  Accordingly, the cap assembly according to the present invention is mounted on the open upper end of a can in a battery having a structure in which a positive electrode / separation membrane / negative electrode structure electrode assembly (jelly roll) is built in a cylindrical can. A safety vent having a predetermined notch formed so as to be ruptured by a high-pressure gas of a battery; a projecting upper end cap connected to the safety vent along an outer peripheral surface thereof; A gasket attached to the outer peripheral surface of the upper end cap, and a fire extinguishing member that contains a fire extinguishing component for preventing battery ignition and at least a part of which is sandwiched between the upper end cap and the gasket. It is configured to be equipped.

  In general, ignition of a battery cell occurs at the top of the cell. Accordingly, the cap assembly according to the present invention reacts more quickly to a temperature change by disposing the fire extinguishing member at the interface between the upper end cap and the gasket, and the fire extinguishing member ignites the battery cell. This can be prevented beforehand.

  The space in which the fire extinguishing member that suppresses the ignition of the battery cell can be attached in this way is extremely limited in terms of the overall structure of the battery. It has a structure that is sandwiched between.

  For example, the interface to which at least a part of the fire extinguishing member is attached may be the upper surface or the outer peripheral surface of the upper end cap.

  Preferably, the fire extinguishing member has a hollow annular shape when viewed from the plane so as to correspond to the shape of the interface between the upper end cap and the gasket, and the outer portion having a size of 20 to 100% in the radial direction is the upper end cap. It is good to be fixed to the interface of the gasket.

  The fire extinguishing member may be of any structure capable of exhibiting an excellent ignition suppression function without deteriorating the performance of the battery, for example, a metal ring containing a flame retardant component or a thin-film hollow shape Any flame retardant film may be used.

  The type of the flame retardant component (that is, flame retardant) is not particularly limited. For example, any one of a halogen flame retardant, a phosphorus flame retardant, and an inorganic compound flame retardant, or those Of the mixture.

  Halogen flame retardants generally exhibit a flame retardant effect by substantially stabilizing radicals generated from a gas. Examples of halogen-based flame retardants include tribromophenoxyethane, tetrabromobisphenol-A (TBBA), octabromodiphenyl ether (OBDPE), brominated epoxy, brominated polycarbonate oligomer, chlorinated paraffin, chlorinated polyethylene, alicyclic chlorine And flame retardants.

  Phosphorus flame retardants generally produce polymetaphosphoric acid by thermal decomposition, which forms a protective layer, and the carbon coating produced by the dehydration action when polymetaphosphoric acid is produced blocks oxygen. Exhibits flame retardant effect. Examples of phosphorus-based flame retardants include phosphates such as red phosphorus and ammonium phosphate, phosphine oxides, phosphine oxide diols, phosphites, phosphates, triphenyl phosphates, phospholipids, triphenyl phosphates, triphenyl phosphates, triphenyl phosphates, triphenyl phosphates, triphenyl phosphates, triphenyl phosphates, triphenyl phosphates, triphenyl phosphates, triphenyl phosphates, triphenyl phosphates.

  Inorganic compound flame retardants are generally decomposed by heat to release incombustible gases such as water, carbon dioxide, sulfur dioxide and hydrogen chloride, and induce endothermic reactions to dilute combustible gases and approach oxygen. The flame retardant effect is exhibited by reducing the generation of cooling and thermal decomposition products by endothermic reaction. Examples of such inorganic compound flame retardants include aluminum hydroxide, magnesium hydroxide, antimony oxide, tin hydroxide, tin oxide, molybdenum oxide, zirconium compound, borate, calcium salt and the like.

  Specifically, the flame retardant component only needs to contain halon. Halon is a carbon compound gas of halogen elements (fluorine, chlorine, bromine), and prevents combustion by preventing the approach of oxygen by blocking the oxidation reaction of combustion products by the subcatalytic action of halogen elements. . As an example of such halon, halon-1211 (Halon-1211: CF2BrCl) is preferable.

  The base material of the flame retardant film is not particularly limited as long as it can stably hold the flame retardant without inducing chemical action inside the battery. Examples of such a film substrate include polyethylene, polypropylene, polyurethane, or a fluorine-based polymer. Preferably, polyurethane or the like that exhibits flame retardancy is used.

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

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

  On the other hand, the fire extinguishing member only needs to have a characteristic of absorbing heat by changing from liquid to gas at a predetermined temperature or higher. That is, when the internal temperature of the battery cell continues to rise and reaches a predetermined temperature before the point of explosion, the fire extinguishing member absorbs ambient heat and blocks ambient air from further rising. Can be effectively prevented.

  The said predetermined temperature should just be 100 degreeC or more, for example, Preferably, it is good to determine in the range of 100 to 200 degreeC.

  In one example, the safety vent has a shape in which the center is bayed downward, and a first notch and a second notch are formed in an upper bent portion and a lower bent portion forming the bay portion, respectively. The first notch has a closed curve, the second notch formed in the lower part has an open curve with one side open, and the second notch is cut deeper than the first notch. It has a structure.

  Therefore, since the second notch is cut deeper than the first notch, the second notch is torn when pressurized gas above the critical pressure pressurizes the safety vent. On the other hand, the first notch acts together with the second notch to lift the bay entrance when pressurized gas below the second critical pressure acts on the safety vent.

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

  That is, since the PTC element is interposed in the position adjacent to the fire extinguishing member, when the PTC element does not operate at a predetermined temperature or higher, the fire extinguishing member immediately absorbs heat to ensure the safety of the battery cell. Can do.

  The present invention also provides a cylindrical battery including the cap assembly.

  In the cylindrical secondary battery according to the present invention, the cap assembly as described above is coupled to the open upper end of the metal can in a state where the jelly-roll electrode assembly is mounted on the cylindrical metal can. The negative electrode is welded to the lower end of the can, and the positive electrode of the electrode assembly is welded to a cap assembly coupled to the upper end in order to seal the battery in a state where the electrode assembly and the electrolyte are incorporated.

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

  In general, a lithium secondary battery is composed of a positive electrode, a negative electrode, a separation membrane, a lithium salt-containing non-aqueous electrolyte, and the like.

  The positive electrode is formed by, for example, applying a mixture of a positive electrode active material, a conductive material and a binder onto a positive electrode current collector and then drying. If necessary, a filler may be further added. The negative electrode is formed by applying and drying a negative electrode material on a negative electrode current collector, and may further contain the above-described components as necessary.

  The separation membrane is preferably formed of an insulating thin film having a high ion permeability and mechanical strength that is interposed between the negative electrode and the positive electrode.

  The lithium salt-containing non-aqueous electrolyte is composed of a non-aqueous electrolyte and a lithium salt, and a liquid non-aqueous electrolyte, a solid electrolyte, an inorganic solid electrolyte, or the like is used as the non-aqueous electrolyte.

  The current collector, the electrode active material, the conductive material, the binder, the filler, the separation membrane, the electrolytic solution, the lithium salt, and the like are known in the art, and detailed descriptions thereof are omitted in this specification.

  What is necessary is just to produce the lithium secondary battery which concerns on this invention by the normal method well-known in this industry. That is, a porous separation membrane may be inserted between the positive electrode and the negative electrode, and the electrolytic solution may be injected there.

  The positive electrode may be prepared, for example, by applying a slurry containing the above-described lithium transition metal oxide active material, conductive material and binder onto a current collector and then drying. Similarly, the negative electrode may be prepared, for example, by applying a slurry containing the above-described carbon active material, conductive material and binder onto a thin film current collector and then drying.

  As described above, the cap assembly according to the present invention can prevent fire of the battery and improve safety by sandwiching a fire extinguishing member containing a fire extinguishing component at the interface between the upper end cap and the gasket. it can.

It is a vertical section perspective view showing a general cylindrical battery. FIG. 2 is a partial cross-sectional perspective view of FIG. 1. It is a perspective view which shows the cylindrical battery which concerns on one Example of this invention. FIG. 4 is an exploded view of FIG. 3. FIG. 4 is a partially enlarged view of FIG. 3. FIG. 4 is a partial cross-sectional perspective view of FIG. 3. It is a perspective view of the safety vent in FIG.

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

  FIG. 3 is a perspective view showing a cylindrical battery according to an embodiment of the present invention, and FIG. 4 is an exploded view of FIG.

  Referring to FIGS. 3 and 4, in the cylindrical battery 100 a according to the present invention, a jelly roll (not shown) is inserted into a can 200, an electrolyte is injected therein, and the can 200 is opened. A cap assembly 300 is attached to the upper end. In addition, the insulating member 400 is seated on the upper end of the cap assembly 300 in order to insulate the positive electrode and the negative electrode, and then the tube 410 is pressed to maintain the insulating state.

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

  Referring to FIGS. 5 and 6 together with FIGS. 3 and 4, the cap assembly 300 includes a safety vent 320 having a predetermined notch so as to be ruptured by the high-pressure gas of the battery, and an outer peripheral surface of the safety vent 320. A projecting upper end cap 310 connected to the upper end cap 310, a gasket 340 attached to the outer peripheral surface of the upper end cap 310, a PTC element 350 interposed between the upper end cap 310 and the safety vent 320, and an upper end cap. And a fire extinguishing member 360 sandwiched at the interface between the gasket 310 and the gasket 340.

  The fire extinguishing member 360 has a hollow ring shape when viewed from above, and most of the outer portion is fixed to the interface between the upper end cap 310 and the gasket 340 in the radial direction.

  Further, the fire extinguishing member 360 is a metal ring containing a flame retardant halon component, and the flame retardant component is included in the base material of the ring in an amount of about 60% by weight based on the total weight of the metal ring. Yes.

  Therefore, the fire extinguishing member 360 absorbs ambient heat when the temperature becomes 100 ° C. or higher, and blocks ambient air, thereby preventing the temperature from rising further. Thereby, the ignition of the battery can be fundamentally prevented, and the safety of the battery can be improved.

  FIG. 7 is a perspective view showing the safety vent of FIG.

  Of the notches 324 and 326 of the safety vent 320, the first notch 324 formed in the upper part is a closed curve, and the second notch 326 formed in the lower part is an open curve with one side opened. Further, the coupling force of the second notch 326 is smaller than that of the first notch 324, and thus the second notch 326 is cut deeper than the first notch 324.

  Therefore, when the internal pressure of the can 200 rises above the critical pressure, the second notch 326 of the safety vent 320 is broken without withstanding the pressure, and the pressurized gas in the can 200 escapes to the outside.

  Those skilled in the art to which the present invention pertains will be able to make various applications and modifications within the scope of the present invention based on the above description.

Claims (15)

A battery assembly having a positive electrode / separation membrane / negative electrode structure (jelly roll) built in a cylindrical can, the cap assembly being mounted on the open upper end of the can,
A safety vent with a predetermined notch formed to rupture by the high pressure gas of the battery;
A protruding top cap connected to it along the outer peripheral surface of the safety vent;
A gasket attached to the outer peripheral surface of the upper end cap;
A fire extinguishing component containing a fire extinguishing component for preventing ignition of the battery, at least a part of which is sandwiched between the upper end cap and the gasket,
A cap assembly, comprising:   The cap assembly according to claim 1, wherein an interface between which at least a part of the fire extinguishing member is sandwiched is an upper surface or an outer peripheral surface of an upper end cap.   The fire extinguishing member has a hollow annular shape when viewed from above, and an outer portion having a size of 20 to 100% in the radial direction is fixed to an interface between the upper end cap and the gasket. Cap assembly as described in 1.   2. The cap assembly according to claim 1, wherein the fire extinguishing member is a metal ring or a thin-film hollow flame retardant film containing a flame retardant component.   The cap assembly according to claim 4, wherein the flame retardant component is one selected from the group consisting of a halogen flame retardant, a phosphorus flame retardant, and an inorganic compound flame retardant, or a mixture thereof. Lee.   The cap assembly according to claim 5, wherein the flame retardant component contains a halon component.   The cap assembly according to claim 4, wherein a base material of the flame retardant film is polyethylene, polypropylene, polyurethane, or a fluorine-based polymer.   The cap assembly according to claim 4, wherein the flame retardant component is contained in the base material of the film in an amount of 20 to 90% by weight based on the total weight of the flame retardant film.   5. The cap assembly according to claim 4, wherein the flame retardant component is included in the base material of the ring in an amount of 20 to 90% by weight based on the total weight of the metal ring.   The cap assembly according to claim 1, wherein the fire extinguishing member has a characteristic of absorbing heat by changing from a liquid to a gas at a predetermined temperature or higher.   The cap assembly according to claim 10, wherein the temperature is 100 ° C. or more.   The safety vent has a shape in which the center is bayed downward, and an upper bent portion and a lower bent portion forming the bay portion are respectively formed with a first notch and a second notch, The first notch is a closed curve, the second notch formed at the bottom is an open curve with one side open, and the second notch is deeper than the first notch. The cap assembly according to claim 1, wherein:   The cap assembly according to claim 1, wherein a PTC element is interposed between the upper end cap and the safety vent.   A cylindrical battery comprising the cap assembly according to any one of claims 1 to 13.   The cylindrical battery according to claim 14, wherein the battery is a lithium secondary battery.

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