KR20090110710A - Secondary battery - Google Patents

Abstract

PURPOSE: A secondary battery is provided to easily discharge gas through gas discharging path and prevent explosion of secondary battery. CONSTITUTION: A secondary battery (100) comprises an electrode assembly (110), can (120), and cap assembly. An opening (121) is formed at one end of the can and contains the electrode assembly. The cap assembly comprises cap up (131), safety device (132), safety belt (133), and insulating gasket (134). A gas discharging hole (131b) is formed at the cap up. The safety device is placed at the lower part of the cap up.

Description

Secondary Battery {SECONDARY BATTERY}

The present invention relates to a secondary battery, and more particularly, to a secondary battery in which a gas discharge path of a safety vent that prevents explosion of a secondary battery is secured to facilitate gas discharge.

Recently, compact and lightweight portable electric / electronic devices such as cellular phones, notebook computers, camcorders, etc. have been actively developed and produced. Therefore, portable electric / electronic devices have a battery pack built therein so that they can be operated even in a place where no separate power source is provided. The battery pack has recently adopted a battery capable of charging and discharging in consideration of economic aspects. Typical batteries include nickel-cadmium (Ni-Cd) batteries, nickel-hydrogen (Ni-MH) batteries, lithium (Li) batteries, and lithium ion (Li-ion) secondary batteries.

In particular, lithium ion secondary batteries have about three times higher operating voltage than nickel-cadmium batteries or nickel-hydrogen batteries, which are widely used as power sources for portable electronic equipment. In addition, it is widely used in view of high energy density per unit weight.

As the lithium ion secondary battery, a rectangular lithium ion secondary battery or a cylindrical lithium ion secondary battery is largely used depending on the shape of the case.

Among these, since the cylindrical lithium ion secondary battery is very easy to manufacture at high power, it is mounted on a hybrid electric vehicle (HEV) and used as an auxiliary power.

Cylindrical lithium ion secondary batteries used in hybrid electric vehicles provide high output power in approximately five seconds to one minute at initial startup of the hybrid electric vehicle.

By the way, driving such as start-up that requires high output power momentarily promotes deterioration of the cylindrical lithium ion secondary battery and shortens the life of the cylindrical lithium ion secondary battery.

In particular, when the temperature of the surrounding environment is very low, such as winter, the temperature variation of the cylindrical lithium ion secondary battery during the instant preheating is severe, and thus the life of the cylindrical lithium ion secondary battery may be further shortened.

As described above, the cylindrical lithium ion battery that is continuously deteriorated generates severe heat, and causes an explosion at some instant, causing explosion.

However, in order to prevent deterioration or unexplained explosion, most cylindrical lithium ion secondary batteries have a safety vent installed therein, and the safety vent is opened when the internal pressure of the cylindrical lithium ion secondary battery increases. The explosion of the lithium ion secondary battery is prevented.

By the way, since the cylindrical lithium ion secondary battery for hybrid electric vehicles requires high output, it rises to very high temperature. Therefore, the cylindrical lithium ion secondary battery carbonizes insulators such as an insulating plate or a separator present therein at the time of ignition to form particles.

In this case, the safety vent for preventing the explosion of the cylindrical lithium ion secondary battery is opened when the internal pressure rise of the cylindrical lithium ion secondary battery is discharged together with the gas and carbonized particles.

However, when the cylindrical lithium ion secondary battery discharges too large particles, the particles may block the gas discharge path.

In this case, in the cylindrical lithium ion secondary battery, the gas discharge path is blocked, and gas is accumulated again inside, and the accumulated gas is ignited by a spark or the like to explode the cylindrical lithium ion secondary battery.

The technical problem of the present invention is to provide a secondary battery in which the gas discharge path of the safety vent to prevent the explosion of the secondary battery is secured to facilitate the discharge of the gas.

The secondary battery of the present invention for achieving the above technical problem is an electrode assembly; An opening formed at one end to accommodate the electrode assembly; And a cap up having a gas discharge hole formed therein, a safety device disposed below the cap up, a safety vent disposed below the safety device, an insulating gasket surrounding the cap up and the safety device, and an outer portion of the safety vent. A cap assembly coupled to the can; Including;

The safety vent has a fracture groove which is broken when the internal pressure of the can becomes a critical pressure, the fracture groove forms fracture surfaces at the time of break, and a linear gas from the fracture surfaces to the gas discharge hole. Characterized in that the discharge path is formed. Here, the break groove may be formed to correspond to the planar shape of the gas discharge hole.

In addition, the cap-up has a circular protrusion formed in the center, a plurality of the gas discharge hole is formed in the circular edge portion of the circular protrusion, the gas discharge hole is formed in an arc shape in the circular edge portion, the fracture groove It may be formed in the longitudinal direction of the circumference of the arc-shaped gas discharge hole.

In this case, the gas discharge hole may include a first gas discharge hole formed in the circular edge portion of the circular protrusion, and a second gas discharge hole formed in the circular edge portion of the circular protrusion and formed symmetrically with the first gas discharge hole. The fracture groove includes a first fracture groove formed in a longitudinal direction of the arc-shaped circumference of the first gas discharge hole, and a second fracture groove formed in a longitudinal direction of the arc-shaped circumference of the second gas discharge hole. Can be done.

Alternatively, the gas discharge hole may include a first gas discharge hole formed in a circular edge portion of the circular protrusion, and a second gas discharge hole formed in a circular edge portion of the circular protrusion and spaced apart from the first gas discharge hole. And a third gas discharge hole formed at a circular edge portion of the circular protrusion and spaced apart from the first gas discharge hole and the second gas discharge hole, wherein the first gas discharge hole is the second gas discharge hole. The hole may be formed in an arc shape larger than the third gas discharge hole, and the fracture groove may be formed in the longitudinal direction of the circumference of the arc-shaped first gas discharge hole.

In addition, the safety vent may be a central groove is formed in the center, bent grooves that cross the center groove and the fracture groove may be further formed. In addition, the fracture groove may be formed to have a deeper depth than the depth of the bent groove. In addition, the shape formed by connecting the fracture groove and the bending groove may be made by selecting any one of a semi-circular, triangular, and square shape.

In addition, the safety vent is a central groove is further formed in the center, the bent groove to cross the center groove is further formed, the fracture groove is an arc-shaped first fracture groove which is connected to the bending groove; And a second fracture groove which is connected to the bending groove and faces the first fracture groove in a shape corresponding to the first fracture groove.

The cap assembly may further include a subassembly disposed under the safety vent, and the subassembly may include an insulation plate disposed under the safety vent; A main plate disposed under the insulating plate and having a central hole formed therein; And a sub plate disposed below the main plate to cover the central hole of the main plate and electrically connected to the safety vent through the central hole.

In this case, the safety vent is formed of a conductive metal material, it is possible to electrically connect the safety element and the sub-plate. In addition, the sub plate may be electrically connected to the electrode assembly.

The present invention has a gas discharge path of the safety vent that operates to prevent the explosion of the secondary battery is secured to facilitate the discharge of the gas to prevent the explosion of the secondary battery, there is an effect that the safety is improved.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings. In the following embodiments, the same reference numerals are used for the same components, and duplicate descriptions of the same components will not be given. In addition, in each embodiment, the same or similar effects and actions will not be redundantly described.

1A is an exploded perspective view of a rechargeable battery according to an exemplary embodiment of the present invention. 1B is a perspective view of a state in which the secondary battery illustrated in FIG. 1A is coupled. FIG. 1C is a partial cross-sectional view taken along line II of the rechargeable battery of FIG. 1B. FIG. FIG. 1D is a plan view of the secondary battery illustrated in FIG. 1B. FIG. 1E is a partial cross-sectional view of the safety vent according to the cutting line II-II of FIG. 1D.

As illustrated in FIGS. 1A to 1E, the secondary battery 100 according to an exemplary embodiment of the present invention includes an electrode assembly 110, a can 120, and a cap assembly 130. In addition, the secondary battery 100 may further include an upper insulating plate 140 and a lower insulating plate 150.

The electrode assembly 110 is formed to include a positive electrode plate 111, a negative electrode plate 112, and a separator 113. Here, the positive electrode plate 111 and the negative electrode plate 112 are stacked with the separator 113 interposed therebetween. In addition, the positive electrode plate 111, the separator 113, and the negative electrode plate 112 stacked on each other are wound in a jelly roll form to form the electrode assembly 110. In this case, a passage 110a is formed at the winding center of the electrode assembly 110. In addition, the electrode assembly 110 may further include a positive electrode tab 114 attached to the positive electrode plate 111 and a negative electrode tab 115 attached to the negative electrode plate 112.

The positive electrode plate 111 is composed of a positive electrode current collector and a positive electrode active material layer. The positive electrode active material layer may be formed of a layered compound containing lithium, a binder to improve bonding strength, and a conductive material to improve conductivity. As the cathode current collector, aluminum is generally used and serves to support the cathode active material layer.

The negative electrode plate 112 includes a negative electrode current collector and a negative electrode active material layer. The negative electrode active material layer may be formed of a binder which contains carbon and improves bonding strength between hard carbon, which is commonly used, or graphite and active material particles. As the negative electrode current collector, copper is generally used and serves to support the negative electrode active material layer.

The separator 113 is interposed between the positive electrode plate 111 and the negative electrode plate 112 to insulate the positive electrode plate 111 and the negative electrode plate 112 and allow ions to pass therethrough. Generally, the material of the separator 113 uses polyethylene (PE) or polypropylene (PP), but the material is not limited thereto.

The can 120 has an opening 121 formed at one end to accommodate the electrode assembly 110. The can 120 has a beading portion 122 formed at an outer circumference thereof. The beading part 122 is formed convex to enter between the lower end of the insulating gasket 134 and the upper surface of the electrode assembly 110. In addition, the can 120 has an opening 121 bent to form a bent portion 123. The bent portion 123 is in close contact with the upper surface of the outer circumference of the insulating gasket 134. Meanwhile, the can 120 is formed of a conductive metal material such as stainless and electrically connected to the negative electrode tab 115 of the electrode assembly 110. In addition, a lower insulating plate 150 may be inserted into the inner lower surface of the can 120 to insulate the lower surface of the electrode assembly 110 from the inner lower surface of the can 120. In addition, the lower insulating plate 150 may have a lower insulating plate center hole through which the negative electrode tab 115 passes, and the negative electrode tab 115 may pass through the lower insulating plate center hole to be electrically connected to the can 120.

The cap assembly 130 includes a cap up 131, a safety device 132, a safety vent 133, and an insulating gasket 134. In addition, the cap assembly 130 may further include a subassembly 135.

The cap up 131 is formed with a circular protrusion 131a protruding from the center. In addition, the cap up 131 is formed with a plurality of gas discharge holes 131b for discharging gas at the circular edge portion of the circular protrusion 131a. Here, the circular protrusion 131a protrudes to the upper portion of the cap up 131 so as to secure a discharge path of the gas generated inside the can 120. The cap up 131 may be formed of a metal material such as stainless steel and may be electrically connected to the safety element 132.

In the present exemplary embodiment, the gas discharge hole 131b formed in the cap up 131 includes a first gas discharge hole 131b1, a second gas discharge hole 131b2, and a third gas discharge hole 131b3.

The first gas discharge hole 131b1 is formed at a circular edge portion of the circular protrusion 131a. Here, the first gas discharge hole 131b1 is formed in a semicircle larger than the second gas discharge hole 131b2 and the third gas discharge hole 131b3. Preferably, the first gas discharge hole 131b1 is formed within a range of about 180 to 360 degrees based on the center of the cylindrical protrusion 131a.

The second gas discharge hole 131b2 is formed at a circular edge portion of the circular protrusion 131a and is spaced apart from the first gas discharge hole 131b1. in this case,

The third gas discharge hole 131b3 is formed at a circular edge portion of the circular protrusion 131a and is spaced apart from the first gas discharge hole 131b1 and the second gas discharge hole 131b2.

The safety device 132 is disposed between the cap up 131 and the safety vent 133. The safety device 132 is formed in a circular ring shape to electrically connect the cap up 131 and the safety vent 133. In the present embodiment, the safety device 132 may be formed of a PTC device. The safety element 132 blocks the current between the cap-up 131 and the safety vent 133 when the temperature of the secondary battery rises above the threshold to prevent overheating and explosion of the secondary battery 100.

The safety vent 133 is disposed below the safety element 132, and a protrusion 133a protruding downward is formed. In addition, the center groove 133b is formed at the center of the protrusion 133a of the safety vent 133. In addition, the safety vent 133 has a fracture groove 133d corresponding to the planar shape of the first gas discharge hole 131b1 of the cap up 131. In the present embodiment, the fracture groove 133d is formed in an arc shape, and the fracture groove 133d is formed in at least a portion in the longitudinal direction of the circumference of the arc-shaped first gas discharge hole 133b1. In addition, the safety vent 133 is formed a bending groove 133c across the center groove 133b, in which case the bending groove 133c is connected to the break groove 133d. In the present embodiment, the safety vent 133 is made of a conductive metal material to electrically connect the safety element 132 and the sub plate 135c.

Here, the fracture groove 133d formed in the safety vent 133 is formed to have a deeper depth than that of the bending groove 133c as shown in FIG. 1E. Therefore, when the safety vent 133 is expanded upward when the internal pressure of the can 120 rises, the semicircular break groove 133d is first cut out. Therefore, the safety vent 133 has a portion cut along the fracture groove 133d to form an open hole, and a portion cut along the fracture groove 133d is cut based on the bending groove 133c and can The gas generated in the interior of the 120 is discharged to the outside.

The insulating gasket 134 is bent a portion of the outer circumference to wrap the cap 131 and the outer circumference of the safety element and the safety vent 133. Here, the insulating gasket 134 is integrally coupled to the can by the beading part 122 and the bent part 123 formed in the can 120. In the present embodiment, the insulating gasket 134 is formed of a resin material such as polyethylene terephthalate (PET) or polyethylene (PE) to insulate the can 120 and the components of the cap assembly 130.

The subassembly 135 is disposed on the bottom surface of the safety vent 133.

In the present embodiment, the subassembly 135 includes an insulating plate 135a, a main plate 135b in close contact with the insulating plate 135a, and a subplate 135c connected to the main plate 135b. Can be.

The insulating plate 135a is disposed between the safety vent 133 and the main plate 135b to insulate the safety vent 133 and the main plate 135b. In this case, the insulating plate 135a is formed on a part of the upper surface of the main plate 135b so as not to interfere with the electrical connection between the safety vent 133 and the sub plate 1335c. 135b) can be insulated.

The main plate 135b has a lower protrusion smaller than the diameter of the main plate 135b, and a central hole 135b1 is formed at the center of the lower protrusion. In addition, gas passage holes 135b2 are formed around the central hole 135b1 formed in the main plate 135b to smoothly discharge the internal gas of the can 120.

The sub plate 135c is connected to the lower part of the main plate 135b to cover the central hole 135a1 of the main plate 135b and is electrically connected to the main plate 135b. In addition, the sub plate 135c may be electrically connected to the safety vent 133. In addition, the subplate 135c is electrically connected to the positive electrode tab 114.

Hereinafter, the operation of the secondary battery having the above configuration will be described in detail.

FIG. 1F is a partial cross-sectional view of a state in which a safety vent is broken due to an increased internal pressure of the rechargeable battery illustrated in FIG. 1C. FIG. 1G is a plan view of a state in which a safety vent is broken due to an increased internal pressure of the rechargeable battery illustrated in FIG. 1D.

1F and 1G, the secondary battery 100 according to an embodiment of the present invention operates by deforming the safety vent 133 to prevent explosion of the secondary battery when the internal pressure of the can 120 rises. Done. In detail, when the internal pressure of the can 120 is increased above the threshold, the safety vent 133 is deformed by protruding upward from the periphery of the central groove 133b of the safety vent 133. In this case, the safety vent 133 is electrically disconnected from the sub plate 135c by the deformation of the central groove 133b, thereby blocking the electrical connection between the positive electrode plate 111 and the safety element 132.

In addition, the safety vent 133 cuts the fracture groove 133d to form the first fracture surface 133e and the second fracture surface 133f, and the first fracture surface 133e and the second fracture surface 133f. ), Gas is discharged. In this case, since the first gas discharge hole 131b1 forms an area larger than the second gas discharge hole 131b2 and the second gas discharge hole 131b3, the first fracture surface 133e and the second fracture surface 133f are formed. The discharge path of the gas flowing between) is relatively large. Accordingly, the first gas discharge hole 131b1 discharges a larger amount of gas than the other gas discharge holes 131b2 and 131b3 to reduce the explosion risk of the secondary battery.

In addition, as illustrated in FIG. 1D, the fracture groove 133d disposed below the arc-shaped first gas discharge hole 131b1 is formed in the longitudinal direction of the circumference of the arc-shaped first gas discharge hole 131b1. The breaking groove 133d is cut in the longitudinal direction of the circumferential portion of the first gas discharge hole 131b1 when the internal pressure of the can 120 rises, so that the first breaking surface 133e and the second wave shown in FIG. An end surface 133f is formed. In this case, as shown in FIG. 1E, the gas discharge path generated inside the can 120 includes the first gas discharge hole 131b1 between the first fracture surface 133e and the second fracture surface 133f. Is formed with a very short path. That is, the gas discharge path flowing between the first breaking surface 133e and the second breaking surface 133f is linearly formed. The linear gas discharge path is in a state where there is no obstacle blocking the flow of gas, and the discharge rate of the gas generated inside the can 120 is significantly increased. As a result, a large amount of gas generated inside the can 120 is discharged at a very fast discharge rate. Therefore, the gas generated inside the can 120 and the particles remaining with the gas are smoothly discharged to the outside of the can 120. That is, the explosion risk of the secondary battery is lowered and the safety of the secondary battery is improved.

2A is a plan view of a secondary battery according to another embodiment of the present invention. FIG. 2B is a perspective view of the safety vent shown in FIG. 2A. FIG. 2C is a plan view of a state in which a safety vent is broken due to an increased internal pressure of the rechargeable battery illustrated in FIG. 2A.

Secondary battery according to another embodiment of the present invention may be formed including an electrode assembly (not shown), can 120, and a cap assembly (not shown). The electrode assembly (not shown) and the can (not shown) in this embodiment may be formed in the same configuration as the above-described embodiment. In addition, the safety device (not shown) and the insulating gasket 134 of the cap assembly (not shown) may also be formed in the same configuration as the above-described embodiment. That is, in the present embodiment, duplicate descriptions of the same components will not be described, and in the present embodiment, a modified example of the cap up 231 and the safety vent 233 of the cap assembly will be described.

First, the cap up 231 has a circular protrusion 231a, and a first gas discharge hole 231b1 and a second gas discharge hole 231b2 are formed around the circular protrusion 231a.

The first gas discharge hole 231b1 is formed in an arc shape at a circular edge portion of the circular protrusion 231a. In this case, the first gas discharge hole 231b may be formed within a range between 130 degrees and 180 degrees based on the center of the circular protrusion 231a.

The second gas discharge hole 231b2 is formed in an arc shape at a circular edge portion of the circular protrusion 231a and is formed symmetrically with the first gas discharge hole 231b1.

The safety vent 233 has a central groove 233b, a bending groove 233c, a first breaking groove 233d, and a first breaking groove 233e. The central groove 233b is formed to protrude downward from the center of the safety vent 233.

The bent groove 233c is formed across the center groove 233b.

The first fracture groove 233d is formed in an arc shape and is connected to the bending groove 233c. In addition, the first rupture groove 233d is located below the first gas discharge hole 231b1. In the present embodiment, the first rupture groove 233d is formed in the longitudinal direction of the circumference of the arc-shaped first gas discharge hole 231b1.

The second fracture groove 233e is formed in an arc shape and is connected to the bending groove 233c. In addition, the second fracture groove 233e is located below the second gas discharge hole 231b2. In the present embodiment, the second fracture groove 233e is formed in the longitudinal direction of the circumference of the arc-shaped second gas discharge hole 231b2.

Here, the first breaking groove 233d and the second breaking groove 233e are formed to have a depth deeper than that of the bending groove 233c. Therefore, when the safety vent 233 expands upward when the internal pressure of the can 120 rises, the semi-circular first breaking groove 233d and the second breaking groove 233e are first cut out. Therefore, a portion cut along the first breaking groove 233d and the second breaking groove 233e opens to form an opening, and is cut along the first breaking groove 233d and the second breaking groove 233e. The cut portion is cut based on the bending groove 233c to discharge the gas generated in the can 120 to the outside. In this case, the portion where the first breaking groove 233d and the second breaking groove 233d and the bending groove 233c form a slight separation distance from each other. Therefore, the cut portions along the first breaking grooves 233d and the second breaking grooves 233e are not separated from the safety vent 233 and are bent based on the bending grooves 233c.

In the secondary battery according to another exemplary embodiment of the present invention, each of the first fracture grooves 233d and the second fracture grooves 233e corresponds to the planar shape of the first gas discharge hole 231b1 and the second gas discharge hole 231b2. Is formed. Therefore, when the internal pressure of the can 120 rises and the safety vent breaks, the first breaking groove 233d is cut to form a first breaking surface 233g and a second breaking surface 233f, and a second The break groove 233e is cut to form a third break surface 233h and a fourth break surface 233i. In this case, gas is discharged between the first fracture surface 233g and the second fracture surface 233f to correspond to the arc shape of the first gas discharge hole 231b1. In addition, gas is discharged between the third fracture surface 233h and the fourth fracture surface 233i so as to correspond to the arc shape of the second gas discharge hole 231b2. That is, in the rechargeable battery according to another exemplary embodiment, the first gas discharge path, the third fracture surface 233h and the fourth fracture surface 233i flowing between the first fracture surface 233g and the second fracture surface 233f may be used. The second gas discharge path flowing between the) is formed. Therefore, the secondary battery which forms the first gas discharge path and the second gas discharge path can simultaneously discharge the internal gas from two places, and thus can discharge a larger amount of gas at once.

Moreover, the first gas discharge path and the second gas discharge path are formed linearly. Therefore, the gas generated inside the can 120 can be discharged at a very fast discharge rate. Therefore, the gas generated inside the can 120 and the particles remaining with the gas are smoothly discharged to the outside of the can 120 even if there is a slight obstacle.

That is, in the secondary battery according to another embodiment of the present invention, the break grooves 233d and 233e of the safety vent 233 operated to prevent explosion of the secondary battery when the internal pressure of the can 120 rises may include gas discharge holes ( 231b1 and 231b2 are formed in a shape corresponding to that of the gas, so that the gas discharge path is secured so that the gas is discharged smoothly, so that the safety of the secondary battery is improved.

3A is a plan view of a secondary battery according to still another embodiment of the present invention. 3B is a perspective view of the safety vent shown in FIG. 3A. FIG. 3C is a plan view of a state in which a safety vent is broken due to an increased internal pressure of the rechargeable battery illustrated in FIG. 3A.

Secondary battery according to another embodiment of the present invention may be formed including an electrode assembly (not shown), can 120, and a cap assembly (not shown). The electrode assembly (not shown) and the can (not shown) in this embodiment may be formed in the same configuration as the above-described embodiment, the safety device (not shown) and insulating gasket 134 of the cap assembly (not shown) Also may be formed in the same configuration as the above-described embodiment. That is, in the present embodiment, the description of the same components will not be duplicated, and in the present embodiment, a modified example of the cap up 331 and the safety vent 333 of the cap assembly will be described.

First, the cap up 331 is formed with a circular protrusion 331a, the circular edge of the circular protrusion 331a, the first gas discharge hole 331b1, the second gas discharge hole 331b2, and the third gas discharge The hole 331b3 is formed.

The first gas discharge hole 331b1 is formed in an arc shape at a circular edge portion of the circular protrusion 331a. Here, the first gas discharge hole 331b1 is formed as an area larger than the second gas discharge hole 331b and the third gas discharge hole 331b3.

The second gas discharge hole 331b2 is formed in an arc shape at a circular edge portion of the circular protrusion 331a and is spaced apart from the first gas discharge hole 331b1.

The third gas discharge hole 331b3 is formed in an arc shape at a circular edge portion of the circular protrusion 331a, and is spaced apart from the first gas discharge hole 331b1 and the second gas discharge hole 331b2.

The safety vent 333 has a center groove 333b, a bending groove 333c, a first break groove 333d, and a second break groove 333e. Here, the safety vent 333 may be formed of a conductive metal material.

The center groove 333b is formed at the center of the safety vent 333.

The bending groove 333c is formed across the central groove 333b.

The first breaking groove 333d is formed to be connected to the bending groove 333c.

The second breaking groove 333e is connected to the bent groove 333c, and the second breaking groove 333e is connected to the first breaking groove 333d.

Here, the bending groove 333c, the first fracture groove 333d and the second fracture groove 333e are connected to each other to form a triangular shape, and the first fracture groove 333d and the second fracture groove 333e are formed. Is formed in the lower portion of the longitudinal path of the arc-shaped first gas discharge hole 333b1.

In addition, the first breaking groove 333d and the second breaking groove 333e are formed to have a depth deeper than that of the bending groove 333c. Therefore, when the safety vent 233 is expanded upward when the internal pressure of the can 120 rises, the first breaking groove 333d and the second breaking groove 333e are first cut out. Therefore, the safety vent 333 has a portion cut along the first breaking groove 333d and the second breaking groove 333e to form an opening, and the first breaking groove 333d and the second breaking groove are formed. The cut portion along the 333e is cut based on the bending groove 333c to discharge the gas generated inside the can 120 to the outside. In this case, the portion where the first rupture groove 333d and the second rupture groove 333e are cut first. That is, the safety vent 333, the break response speed to the critical pressure is very fast, thereby improving the gas discharge rate. Therefore, the gas and particles inside the discharge rate is very fast, even if there is a slight obstacle is discharged without stopping the discharge flow. Therefore, the explosion risk of the secondary battery is lowered, so that the safety of the secondary battery is improved.

In addition, the first fracture groove 333d and the second fracture groove 333e are positioned under the first gas discharge hole 333b1 to form a linear gas discharge path, thereby improving the discharge rate of the gas.

In addition, since the first gas discharge hole 331b1 forms an area larger than the second gas discharge hole 331b2 and the second gas discharge hole 331b3, the first fracture surface 133f and the second fracture surface 133g are formed. The discharge path of the gas flowing in between is formed relatively large. Therefore, the first gas discharge hole 331b1 discharges a larger amount of gas than the other gas discharge holes 331b2 and 331b3 to lower the explosion risk of the secondary battery.

4A is a plan view of a secondary battery according to still another embodiment of the present invention. 4B is a perspective view of the safety vent shown in FIG. 4A. FIG. 4C is a plan view of a state in which a safety vent is broken due to an increased internal pressure of the rechargeable battery illustrated in FIG. 4A.

Secondary battery according to another embodiment of the present invention may be formed including an electrode assembly (not shown), can 120, and a cap assembly (not shown). The electrode assembly (not shown) and the can (not shown) in this embodiment may be formed in the same configuration as the above-described embodiment. In addition, the safety device (not shown) and the insulating gasket 134 of the cap assembly (not shown) may also be formed in the same configuration as the above-described embodiment. That is, in the present embodiment, duplicate descriptions of the same components will not be described, and in the present embodiment, modifications of the cap up 431 and the safety vent 433 of the cap assembly will be described.

First, the cap up 431 is formed with a circular protrusion 431a, the first gas discharge hole (431b1) and the second gas discharge hole (431b2) is formed in the circular edge portion of the circular protrusion 431a.

The first gas discharge hole 431b1 is formed in an arc shape at a circular edge portion of the circular protrusion 431a.

The second gas discharge hole 431b2 is formed in an arc shape at a circular edge portion of the circular protrusion 431a, and is spaced apart from the first gas discharge hole 431b1, and is symmetrical with the first gas discharge hole 431b1. Is formed.

The safety vent 433 includes a center groove 433b, a bending groove 433c, a first fracture groove 433d, a second fracture groove 433e, a third fracture groove 433f, and a fourth fracture groove 433g. ) Is formed.

The center groove 433b is formed at the center of the safety vent 433.

The bent groove 433c is formed across the center groove 433b.

The first fracture groove 433d is connected to the bending groove 433c.

The second fracture groove 433e is connected to the bending groove 433c and the first fracture groove 433d.

The third fracture groove 433f is connected to one point 433c1 of the bending groove 433c from which the first fracture groove 433d is connected, and is formed to face the first fracture groove 433d.

The fourth fracture groove 433g is connected to one point 433c2 of the bending groove 433c which is connected to the second fracture groove 433e, and is formed to face the second fracture groove 433e. In addition, the fourth fracture groove 433g is connected to the third fracture groove 433f.

In addition, the first fracture grooves 433d, the second fracture grooves 433e, the third fracture grooves 433f, and the fourth fracture grooves 433g are connected to each other to form a quadrangular shape, and the first gas discharge hole 433b1 is provided. ) And the second gas discharge hole 433b2.

In addition, the first fracture groove 433d, the second fracture groove 433e, the third fracture groove 433f, and the fourth fracture groove 433g are formed to have a deeper depth than that of the bending groove 433c. Therefore, the first fracture groove 433d, the second fracture groove 433e, the third fracture groove 433f, and the fourth fracture groove 433g are broken before the bending groove 433c, and thus the first fracture surface 433h. The second fractured surface 433i, the third fractured surface 433j, and the fourth fractured surface 433k are formed. In this case, the first fracture grooves 433d, the second fracture grooves 433e, the third fracture grooves 433f, and the fourth fracture grooves 433g are slightly divided with the incision grooves 433c and the portions 433c1 and 433c2. Form the separation distance. Accordingly, the first fracture groove 433d, the second fracture groove 433e, the third fracture groove 433f and the fourth fracture groove 433g are not separated from the safety vent 433 based on the bending groove 433c. Not bent.

According to another embodiment of the present invention, when the safety vent 433 is broken due to an increase in the internal pressure of the can, the first fracture groove 433d and the second fracture groove 433e are cut to form a first fracture surface. 433h and a second fracture surface 433i are formed. In this case, gas is discharged between the first fracture surface 433h and the second fracture surface 433i corresponding to the arc shape of the first gas discharge hole 431b1. That is, a linear first gas discharge path is formed between the first fracture surface 433h and the second fracture surface 433i to the first gas discharge hole 431b1.

In addition, when the safety vent 433 is broken due to an increase in the internal pressure of the can 120, the third breaking groove 433f and the fourth breaking groove 433g are cut to cut the third breaking surface 433j and the fourth wave. A cross section 433k is formed. In this case, gas is discharged between the third fracture surface 433j and the fourth fracture surface 433k to correspond to the arc shape of the second gas discharge hole 431b2. That is, a linear second gas discharge path is formed between the third fracture surface 433j and the fourth fracture surface 433k to the second gas discharge hole 431b2.

In this case, the portion where the first fracture groove 433d and the second fracture groove 433e extend, and the portion where the third fracture groove 433f and the second fracture groove 433g continue, are opened first. That is, the safety vent 433 has a very fast response time for breaking against the critical pressure, thereby improving the gas discharge rate. Therefore, the gas and particles inside the discharge rate is very fast, even if there is a slight obstacle is discharged without stopping the discharge flow. Therefore, the explosion risk of the secondary battery is lowered, so that the safety of the secondary battery is improved. Further, the safety vent 433 is secured to the first gas discharge hole (431b1) and the second gas discharge hole (431b2), so that the gas and particles can be easily discharged.

1A is an exploded perspective view of a rechargeable battery according to an exemplary embodiment of the present invention.

1B is a perspective view of a state in which the secondary battery illustrated in FIG. 1A is coupled.

FIG. 1C is a partial cross-sectional view taken along line II of the rechargeable battery of FIG. 1B. FIG.

FIG. 1D is a plan view of the secondary battery illustrated in FIG. 1B.

FIG. 1E is a partial cross-sectional view of the safety vent according to the cutting line II-II of FIG. 1D.

FIG. 1F is a partial cross-sectional view of a state in which a safety vent is broken due to an increased internal pressure of the rechargeable battery illustrated in FIG. 1C.

FIG. 1G is a plan view of a state in which a safety vent is broken due to an increased internal pressure of the rechargeable battery illustrated in FIG. 1D.

2A is a plan view of a secondary battery according to another embodiment of the present invention.

FIG. 2B is a perspective view of the safety vent shown in FIG. 2A.

FIG. 2C is a plan view of a state in which a safety vent is broken due to an increased internal pressure of the rechargeable battery illustrated in FIG. 2A.

3A is a plan view of a secondary battery according to still another embodiment of the present invention.

3B is a perspective view of the safety vent shown in FIG. 3A.

FIG. 3C is a plan view of a state in which a safety vent is broken due to an increased internal pressure of the rechargeable battery illustrated in FIG. 3A.

4A is a plan view of a secondary battery according to still another embodiment of the present invention.

4B is a perspective view of the safety vent shown in FIG. 4A.

FIG. 4C is a plan view of a state in which a safety vent is broken due to an increased internal pressure of the rechargeable battery illustrated in FIG. 4A.

<Explanation of symbols for the main parts of the drawings>

110; Electrode assembly 111; Positive plate

112; Negative electrode plate 113; Separator

114; Positive electrode tab 115; Negative electrode tab

120; Can 121; Opening

122; Beading portions 130, 230, 330, 430; Cap assembly

131, 231, 331, 431; Cap up 131a; Circular protrusions

131b; Gas discharge hole 132; Safety element

133; Safety vent 133a; protrusion

133b, 233b, 333b, 433b; Central groove 133c, 233c, 333c, 433c; Bending Home

133d; Breaking groove 134; Insulation Gasket

135; Subassembly 135a; Main plate

135a1; Lower protrusion 135a2; Concourse

135a3; Gas through hole 135b; Insulation Plate

135c; Subplate 140; Upper insulation plate

141; Upper insulating plate center hole 142; Electrolytic Solution Passing Hole

150; Lower insulation plate 151; Lower insulation plate center hole

Claims (12)

Electrode assembly; An opening formed at one end to accommodate the electrode assembly; And The can includes a cap up having a gas discharge hole, a safety device disposed below the cap up, a safety vent disposed below the safety device, an insulation gasket surrounding the cap up and the safety device, and an outer portion of the safety vent. A cap assembly coupled with; Including; The safety vent has a fracture groove which is broken when the internal pressure of the can becomes a critical pressure, the fracture groove forms fracture surfaces at the time of break, and a linear gas from the fracture surfaces to the gas discharge hole. A secondary battery, characterized in that the discharge path is formed. The method of claim 1, The break groove is a secondary battery, characterized in that formed to correspond to the planar shape of the gas discharge hole. The method of claim 1, The cap-up has a circular protrusion formed in the center, a plurality of the gas discharge hole is formed in the circular edge portion of the circular protrusion, the gas discharge hole is formed in an arc shape in the circular edge portion, the fracture groove is A secondary battery, characterized in that formed in the longitudinal direction of the circumference of the arc-shaped gas discharge hole. The method of claim 3, wherein The gas discharge hole includes a first gas discharge hole formed in a circular edge portion of the circular protrusion, and a second gas discharge hole formed in a circular edge portion of the circular protrusion and formed symmetrically with the first gas discharge hole. , The fracture groove may include a first fracture groove formed in a longitudinal direction of the arc-shaped circumferential portion of the first gas discharge hole, and a second fracture groove formed in a longitudinal direction of the arc-shaped circumferential portion of the second gas discharge hole. Secondary battery made with. The method of claim 3, wherein The gas discharge hole may include a first gas discharge hole formed in a circular edge portion of the circular protrusion, a second gas discharge hole formed in a circular edge portion of the circular protrusion and spaced apart from the first gas discharge hole; It is formed in the circular edge portion of the circular protrusion and consists of a third gas discharge hole spaced apart from the first gas discharge hole and the second gas discharge hole, The first gas discharge hole is formed in an arc shape larger than the second gas discharge hole and the third gas discharge hole, and the fracture groove is formed in the longitudinal direction of the circumference of the first gas discharge hole of the arc shape. Secondary battery made with. The method of claim 1, The safety vent is a secondary battery, characterized in that the center groove is formed in the center, the bent groove is further formed to cross the center groove and the fracture groove. The method of claim 6, The break groove is a secondary battery, characterized in that having a deeper depth than the depth of the bent groove. The method of claim 6, The shape of the fracture groove and the bent groove is formed by selecting any one of a semi-circular, triangular, and square shape. The method of claim 1, The safety vent has a central groove is further formed in the center, the bent groove is further formed to cross the central groove, The breaking groove An arc-shaped first fracture groove connected to the bending groove; And And a second fracture groove which is connected to the bending groove and faces the first fracture groove in a shape corresponding to the first fracture groove. The method of claim 1, The cap assembly further includes a sub-assembly disposed under the safety vent, The sub-assembly includes an insulating plate disposed under the safety vent; A main plate disposed under the insulating plate and having a central hole formed therein; And, And a sub plate disposed below the main plate to cover the central hole of the main plate and electrically connected to the safety vent through the central hole. The method of claim 10, The safety vent is formed of a conductive metal material, the secondary battery, characterized in that for electrically connecting the safety element and the sub-plate. The method of claim 10, The sub plate is secondary battery, characterized in that electrically connected with the electrode assembly.

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