KR101056956B1 - Safety vent and lithium secondary battery comprising same - Google Patents

Abstract

The present invention relates to a safety vent of a battery and a lithium secondary battery including the same, and a safety van capable of efficiently stabilizing by blocking the flow of current and discharging the gas to the outside when an abnormal pressure rises inside the battery, and including the same. It relates to a lithium secondary battery. According to the present invention, a notch is formed in a plate to block the current flow of the battery under the breaking pressure, and the notch ruptures under the breaking pressure to release the gas inside the cell to the outside, wherein the notch is spiraled from the center of the plate. Characterized in that formed. The safety vent and the lithium secondary battery including the same according to the present invention have the effect of releasing the pressurized gas to the outside of the battery when the pressure inside the battery rises and blocking the current to seek stability of the battery, and the structure is simple. There is an effect of increasing the space utilization between the and the safety vent.

Safety Vent, Top Cap, Cap Assembly, Spiral Notch, Battery

Description

Safety vent and lithium secondary battery comprising same {SAFETY-VENT, AND LITHIUM SECONDARY BATTERY COMPRISING THE SAME}

The present invention relates to a safety vent of a battery and a lithium secondary battery including the same, and more particularly, safety that can efficiently stabilize the flow by blocking current flow and discharging gas to the outside when abnormal pressure rises inside the battery. It relates to a vent and a lithium secondary battery comprising the same.

As the development and demand for mobile devices increases, the demand for secondary batteries as energy sources is increasing rapidly. Among them, many studies have been conducted, commercialized and widely used for lithium secondary batteries with high energy density and high discharge voltage. have.

However, since lithium secondary batteries have high operating potentials, high energy can flow instantaneously, and a dendrite phase of lithium metal is formed on the surface of the negative electrode, thereby degrading the safety of the battery. In addition, since the positive electrode materials used in the battery greatly increase the chemical activity during overcharging, there is a possibility that the internal pressure of the battery is rapidly increased by generating a large amount of gas by reacting with the electrolyte, and in some cases, the battery itself may explode. Therefore, many studies on the safety of the battery are in progress, and various safety devices have been developed and installed in the battery.

A representative of these safety devices is the safety-vent of the battery. The safety vane is mainly installed in the cap assembly that is coupled to the top opening of the can, and when the internal pressure of the battery is kept below a certain level, the safety vane only serves to seal the inside of the battery, but the internal pressure of the battery is higher than a certain level. When raised, gas is discharged to the outside of the can, thereby preventing the internal pressure of the battery from rising above a threshold at which stability is a problem.

Representative examples of such safety devices are disclosed in US Pat. No. 5,853,912.

The safety device having the structure of the prior art such as the US patent has a problem in that the structure is generally complicated compared to its function, and the volume occupied by the battery is a burden for the optimal design of the battery.

Accordingly, the present invention is to provide a safety van and a battery having the same, the structure is simple, which can give a high space utilization between the top gap and the safety van.

The present invention has been made to solve the above problems of the prior art,

A notch is formed in the plate to block the current flow of the cell under the breaking pressure, and the notch forming portion is ruptured under the breaking pressure to release the gas inside the cell to the outside, wherein the notch spirals from the center of the plate. It provides a safety van characterized in that formed.

In addition, in the present invention, the notch provides a safety van, characterized in that deeply dug toward the center.

In addition, in the present invention, the plate thickness of the notched portion is provided, the safety band, characterized in that it has a thickness range of 0.1 to 0.5 compared to the plate thickness of the portion is notched.

In addition, in the present invention, the plate provides a safety van, characterized in that the aluminum metal plate of 0.15 ~ 0.3 mm thick.

In addition, in the present invention, the plate of the notched portion is provided with a safety van, characterized in that having a thickness range of 0.04 ~ 0.07 mm.

In addition, in the present invention, the blocking pressure provides a safety van, characterized in that 5 to 15 Kgf / ㎠.

In addition, in the present invention, the burst pressure provides a safety van, characterized in that 17 ~ 25 Kgf / ㎠.

Also,

A generator having an anode, a cathode, and a separator;

A can surrounding the generator; And

A battery having a top cap and a safety vent having one or more gas outlets formed thereon, the battery comprising a cap assembly located at an upper opening of the can,

The safety van provides a battery which is characterized in that the safety van of the present invention.

In the battery of the present invention, there is provided a battery having a positive temperature coefficient element between the top cap and the safety vent, the PTC element (positive temperature coefficient element) for blocking current by increasing the battery resistance significantly when the temperature inside the battery increases. to provide.

The safety vent according to the present invention and the lithium secondary battery including the same have an effect of releasing the pressurized gas to the outside of the battery when the pressure rises inside the battery and blocking current to seek stability of the battery. In addition, since the structure is simple, there is an effect of increasing the space utilization between the top cap and the safety vent.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

The present invention,

A notch is formed in the plate to block the current flow of the cell under the breaking pressure, and the notch forming portion is ruptured under the breaking pressure to release the gas inside the cell to the outside, wherein the notch spirals from the center of the plate. Characterized as formed.

The notch refers to a cutout formed in a plate or the like, and is a term well known to those skilled in the art.

The plate thickness (a) of the portion where the notch is formed is preferably in the range of 0.1 to 0.5 thickness relative to the plate thickness (b) of the portion where the notch is not formed (see FIG. 3B). The plate part in which the notch was formed in the said range can play a desired action under a breaking pressure or a bursting pressure, and can aim at safety of a battery.

The plate used for the safety van is preferably an aluminum metal plate of 0.15 ~ 0.3 mm thick. An aluminum metal plate is a preferable material for manufacturing a safety band because of its good electrical conductivity and light weight.

If the plate used in the safety van is an aluminum metal plate as described above, the plate of the notched portion is appropriately to have a thickness range of 0.04 ~ 0.07 mm.

In particular, the safety vane of the present invention is a metal flat plate is not a large space occupied by the vant has an effect that can greatly increase the space utilization of the battery.

The breaking pressure or bursting pressure may be arbitrarily set by those skilled in the art according to the purpose and size of the battery, but in the cylindrical battery, the breaking pressure is 5 to 15 kgf / cm 2 and the bursting pressure is 17 to 25 Kgf / It is appropriate that it is cm 2.

In addition, the present invention,

A generator having an anode, a cathode, and a separator;

A can surrounding the generator; And

The present invention relates to a battery including a top cap which serves as a positive electrode terminal and has one or more gas outlets formed therein, and the cap assembly positioned at the top opening of the can, having the safety vent of the present invention.

In the battery of the present invention, a PTC element (Positive Temperature Coefficient element) may be further provided between the top cap and the safety vent to block a current by greatly increasing battery resistance when the temperature inside the battery increases.

Hereinafter, with reference to the drawings according to an embodiment of the present invention will be described in more detail, but is not intended to limit the scope of the invention thereby.

1 is a partial cross-sectional view of a lithium secondary battery according to an embodiment of the present invention.

Referring to FIG. 1, a battery 100 according to the present invention inserts a power generator 300 into a can 200 and injects an electrolyte therein, and a cap assembly 400 in an upper opening of the can 200. It is manufactured by mounting.

The cap assembly 400 is a PTC element 420 for blocking the top cap 410 and overcurrent in the airtight gasket 500 installed in the upper beading portion 210 of the can 200 and for reducing the internal pressure. Safety vent 430 is installed in close contact. The top cap 410 is protruded upward and serves as a positive electrode terminal by connection with an external circuit. The safety vane 430 has a lower end thereof connected to the anode of the power generator 300 through the current blocking member 440 and the anode lead 310.

As shown in Figure 2, the safety vent 430 is a conductive thin plate, the notch 434 is formed spirally from the center thereof. It is preferable that the spiral notch is dug deeper toward the center (that is, it is preferable that the plate thickness of the portion is made thinner by the depth of the incision groove because the incision groove is deep wave toward the center). In this case, the notch at the center is formed with a deeper incision groove than the notch at the outer side, so that when the pressure is applied, the center portion can protrude upward more easily than at the outer side.

When the pressurized gas presses the safety vent 430, when the pressure reaches the cutoff pressure, the notched plate is lifted upwards, and the protrusion 442 fixed to the center portion 432 falls off. The current flow of the battery is interrupted. The blocking pressure can be arbitrarily set by those skilled in the art according to the use and size of the battery, but in the case of a cylindrical battery that is commonly used, it is appropriate that it is about 5 to 15 kgf / cm 2, and more preferably 10 to 12 kgf / cm 2.

When the pressurized gas reaches the burst pressure beyond the blocking pressure, the notch is ruptured and the sealed plate is opened, thereby allowing the pressurized gas inside the battery to be discharged toward the top cap. Since the top cap has one or more outlets, pressurized gas may be discharged through them to prevent explosion of the battery.

The bursting pressure may be arbitrarily set by those skilled in the art according to the use and size of the battery, but in the case of a cylindrical battery that is commonly used, it is appropriate that it is about 17 to 25 kgf / cm 2, and more preferably 19 to 21 kgf / cm 2.

The current blocking member 440 blocking the current of the battery is installed under the safety vent 430.

The current blocking member 440 is provided in the auxiliary gasket 510 as a conductive plate. Preferably, the material of the current blocking member 440 is made of the same material as the safety vent 430, and the auxiliary gasket 510 can prevent the current blocking member 440 and the safety vent 430 from being energized. It is made of polypropylene material.

3A shows an example of the current blocking member 440 according to the present invention. Referring to this, the current blocking member 440 has a plurality of through holes 441 through which gas is discharged along a side surface thereof. A protrusion 442 protruding upward is formed at the center thereof, and a through hole 443 and a bridge 444 connecting the through hole 443 are formed symmetrically with respect to the protrusion 442. . The protrusion 442 is welded to the lower end of the center portion 432 of the safety vent 430. As shown in FIG. 3B, the notch 445 is formed in the bridge 444, and when the pressurized gas fills the inside of the battery to be above the cutoff pressure, the center 432 is lifted up and welded to the center 432. The protrusion 442 is separated from the main body of the current blocking member 440 as the notch 445 is cut out.

The number of through holes 443 formed in the current blocking member 440 is generally about 3 to 5, and the notches 445 are formed in the bridge 444 connecting the through holes 443 with a radially symmetrical structure. Is formed.

As an example, the current blocking members 440 are made of aluminum having a thickness of 0.4 to 0.5 mm with respect to an outer diameter of 8 to 11 mm, and six through holes 441 have a diameter of 1.0 to 1.5 mm. The protrusion 442 is formed with a diameter of 1.4 to 1.6 mm and a protrusion height of 0.15 to 0.3 mm, and the through hole 443 has a width of 0.4 to 0.7 mm and a circumferential length of 1.5 to 3.5 mm as its center radius. The distance (distant from the center of the projection) is 1.0 to 2 mm, and the notch 445 of the bridge 444 is composed of a cutout groove of about 40 to 100 탆 deep.

4a to 4c illustrate the principle of operation of the structure.

Referring to FIG. 4A, when the internal pressure of the battery rises due to the gas generated by abnormal operation of the battery, the pressurized gas is formed in the through hole 441 and the through hole 443 formed in the current blocking member 440. Exit through the pressure is applied to the safety vent 430.

When the pressure of the gas is greater than the blocking pressure, the central portion 432 of the safety van 430 is lifted upward by the pressure of the gas pressurizing the safety vane 430. At this time, the protrusion 442 of the current blocking member 440 that is welded to the bottom of the central portion 432 is separated from the current blocking member 440 as shown in FIG. 4B while its notch 445 is cut away. ) Will be lifted and disconnection will be applied.

As such, the central portion 432 of the safety vane 430 may be lifted up due to the notch formed in the safety vane 430, and the notch portion may be flexibly bent by the gas pressure from the central portion 432. The plate will be lifted up. Accordingly, the current blocking member 440, the safety vent 430, the PTC element 420, and the top cap 410 are connected to the safety vent 430 by the protrusion 442 having the current that is energized. The current is blocked while falling off from the 440.

In the case where there is additional gas generation even after the current is first cut off, the safety vane 430 is continuously energized by the increased gas pressure, and when the gas pressure is greater than the burst pressure, as shown in FIG. As the notch 434 of 430 breaks, the gas inside the battery is discharged to the outside. That is, as the notch 434 formed in the safety vent 430 breaks without being able to withstand the gas pressure inside the battery, the center portion 432 of the safety vent 430 is cut off from the safety vent 430 and lifted up. Gas leaked through the breakage gap is discharged to the outside through the hole 412 formed in the top cap 410 to lower the internal pressure of the battery. At this time, since the notch 434 is a spiral open curve, and a part of the notch is not formed, the part of which the notch is not formed is not broken, and only the part of which the notch is formed is broken, and the center part 432 is a safety band ( 430 is not completely separated from the attached state.

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.

1 is a schematic cross-sectional view showing the structure of a lithium secondary battery according to one embodiment of the present invention.

2 is a perspective view of the safety van of the present invention.

FIG. 3A is a perspective view of a current blocking member used in the battery of FIG. 1, and FIG. 3B is a cross-sectional view showing a side cut through the center of FIG. 3A.

4A to 4C are cross-sectional schematic diagrams illustrating an operation process when a pressurized gas is generated in the battery of FIG. 1.

Brief description of the reference numbers

100: battery

200: can 210: bead

300: generator 310: positive lead

400: assembly 410: top cap

412 hole 420 PTC element

430: safety band 432: the center

434: notch 440: current blocking member

441 through hole 442 projection

443: through hole 444: bridge

445 notch

500: gasket 510: auxiliary gasket

Claims (10)

In the safety vane is formed in the plate to cut off the current flow of the battery under the breaking pressure, the notch forming portion is ruptured under the breaking pressure to release the gas inside the battery to the outside, The notch is helically formed from the center of the plate, the plate thickness of the notched portion is a safety band, characterized in that it has a thickness range of 0.1 ~ 0.5 compared to the plate thickness of the portion not. The safety vane of claim 1, wherein the notch is deeply dug toward the center. delete The safety vane of claim 1, wherein the plate is an aluminum metal plate having a thickness of 0.15 to 0.3 mm. 2. The safety vane of claim 1, wherein the notched plate has a thickness in the range of 0.04 to 0.07 mm. The safety vane of claim 1, wherein the blocking pressure is 5 to 15 Kgf / cm 2. According to claim 1, wherein the bursting pressure is a safety vent, characterized in that 17 ~ 25 Kgf / ㎠. In the safety vane is formed in the plate to cut off the current flow of the battery under the breaking pressure, the notch forming portion is ruptured under the breaking pressure to release the gas inside the battery to the outside, The notch is a safety band, characterized in that formed in a spiral from the center of the plate made of aluminum metal plate of 0.15 ~ 0.3mm thick. A generator having an anode, a cathode, and a separator; A can surrounding the generator; And A battery having a top cap and a safety vent having one or more gas outlets formed thereon, the battery comprising a cap assembly located at an upper opening of the can, The battery is characterized in that the safety vent according to any one of claims 1, 2, 4 to 8. 10. The battery according to claim 9, wherein a PTC element (positive temperature coefficient element) is provided between the top cap and the safety vent to block a current by a large increase in battery resistance when the temperature inside the battery increases.

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