High-safety lithium battery pack

Abstract

The invention provides a high-safety lithium battery pack. The high-safety lithium battery pack comprises a box body, a box cover, a waterproof ventilation valve and a plurality of battery packs, the box body is used for accommodating the battery pack, the box cover covers the opening side of the box body, a gap is formed between the battery pack and the box cover, and the waterproof ventilation valve is arranged on the box cover; the waterproof ventilation valve comprises a valve body, a valve element, a spring and a material box, the valve body is provided with a pressure relief cavity, an exhaust channel and a through hole, the through hole is used for communicating the exhaust channel with the pressure relief cavity, the valve element is located in the pressure relief cavity, a first sealing ring is arranged at the position where the valve element makes contact with the pressure relief cavity, and the spring is used for making the valve element abut against the first sealing ring; and the material box is filled with a flame retardant. According to the high-safety lithium battery pack, the flame retardant is arranged in the waterproof ventilation valve through the material box, when the waterproof ventilation valve leaks pressure outwards, sparks overflowing along with airflow are extinguished through the flame retardant, electronic accessories outside the battery pack are prevented from being ignited during thermal runaway, and therefore the safety performance of the battery pack is improved.

Description

Technical Field

[0001] The present invention relates to the field of lithium battery production, and in particular to a highly safe lithium battery pack. Background Art

[0002] In recent years, new energy vehicles have developed rapidly, and the production technology of battery packs, which are the core of new energy vehicles, has also received attention. The energy storage capacity of battery packs is one of the key factors in extending the driving range of new energy vehicles.

[0003] However, as the energy density of the battery pack increases, the probability of thermal runaway of the battery pack also increases. Thermal runaway of the battery pack can easily cause the vehicle to catch fire, and it is difficult to extinguish a fire after a high-energy-density battery pack catches fire. Therefore, reducing thermal runaway of the battery pack and avoiding fires caused by thermal runaway are the key to improving the safety of new energy vehicles.

[0004] In the prior art, a waterproof vent is installed on the battery pack to reduce the safety issues caused by thermal runaway of the battery pack. However, the internal structure of new energy vehicles is compact. When thermal runaway occurs, the pressure is released from the vent, and the internal flame overflows, which can easily ignite other electronic components around the battery pack.

[0005] Therefore, how to improve the safety performance of existing battery packs is a problem that needs to be solved. Summary of the invention

[0006] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a highly safe lithium battery pack to prevent the gas discharged during thermal runaway of the battery pack from carrying flames and igniting other electronic components around the battery pack, thereby improving the safety performance of the battery pack.

[0007] The objective of the present invention is achieved through the following technical solutions:

[0008] A highly safe lithium battery pack, comprising: a box body, a box cover, a waterproof and breathable valve and a plurality of battery packs;

[0009] The box body is used to accommodate the battery pack, the box cover is arranged on the opening side of the box body, a space is arranged between the battery pack and the box cover, and the waterproof and breathable valve is arranged on the box cover;

[0010] The waterproof breathable valve comprises a valve body, a valve core, a spring and a material box, the valve body is provided with a pressure relief chamber, an exhaust passage and a through hole, the through hole is used to connect the exhaust passage and the pressure relief chamber, the valve core is located in the pressure relief chamber, a first sealing ring is provided at a position where the valve core contacts the pressure relief chamber, the spring is used to make the valve core abut against the first sealing ring, and the material box is provided on the valve body;

[0011] The material box is filled with a flame retardant, and when high-pressure gas flows through the exhaust channel, the flame retardant in the material box is drawn into the exhaust channel.

[0012] In one of the embodiments, the waterproof breathable valve also includes a feeding sleeve, which is embedded in the inner wall of the exhaust channel, and a spiral pipe is provided at the contact point between the feeding sleeve and the inner wall of the exhaust channel, and the spiral pipe is connected to the material box, and the spiral pipe extends from the side close to the material box toward the position of the through hole; a convex ring is provided on the inner wall of the feeding sleeve, and the convex ring is located on the end of the feeding sleeve close to the through hole, and the convex ring narrows the exhaust channel, and a plurality of feeding holes are opened on the convex ring, and the feeding holes are used to connect the exhaust channel and the spiral pipe.

[0013] In one of the embodiments, the starting position and the ending position of the convex ring are both provided with chamfers, and the delivery hole is located on the chamfers.

[0014] In one of the embodiments, the valve core is provided with a ventilation hole and a ventilation chamber, the ventilation hole faces the through hole, a breathable membrane and a sealing cover are provided in the ventilation chamber, and a notch communicating with the pressure relief chamber is provided on the sealing cover.

[0015] In one embodiment, the waterproof breathable valve also includes a delayed sealing component, which includes an outer ring, a guide plate and a plurality of deformable buckles, wherein the guide plate is arranged on the cover, and a gap is provided between the outer wall of the guide plate and the inner wall of the pressure relief chamber, and the deformable buckle includes a memory metal sheet and a heat conductive block, wherein the heat conductive block is welded to the guide plate, and the memory metal sheet is vertical; the outer ring is arranged on the valve body, and a slot matching the memory metal sheet is provided on the surface of the outer ring.

[0016] In one embodiment, the deformation buckles are distributed in a circular array with the axis of the guide disk as the center.

[0017] In one of the embodiments, the heat conductive block separates the memory metal sheet and the guide plate.

[0018] In one embodiment, the waterproof breathable valve further includes a nut, and an outer wall of the valve body is provided with an external thread matching the nut.

[0019] In one embodiment, the valve body is provided with a sleeve, the spring is located in the sleeve, the valve core is provided with a center rod matching the sleeve, a stop ring is provided at the end of the center rod, the center rod passes through the sleeve, and the spring is abutted against the stop ring.

[0020] In one of the embodiments, a second sealing ring is provided on the valve body at a position in contact with the box cover.

[0021] The above-mentioned high-safety lithium battery pack has a flame retardant built into the waterproof and breathable valve through a material box. When the waterproof and breathable valve releases pressure outward, the flame retardant is used to extinguish sparks that overflow with the airflow, thereby avoiding ignition of electronic components outside the battery pack during thermal runaway, thereby improving the safety performance of the battery pack. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0023] Figure 1 A schematic diagram of the structure of a high-safety lithium battery pack;

[0024] Figure 2 This is the assembly state diagram of the waterproof breathable valve;

[0025] Figure 3 This is a schematic diagram of the disassembly of the waterproof breathable valve;

[0026] Figure 4 Schematic diagram of the valve body;

[0027] Figure 5 This is the internal structure diagram of the waterproof breathable valve under normal ventilation status;

[0028] Figure 6 This is a diagram of the internal structure of the waterproof breathable valve in the thermal runaway state. DETAILED DESCRIPTION

[0029] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thoroughly understood.

[0030] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only and do not represent the only implementation method.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0032] See also Figure 1 The present invention provides a highly safe lithium battery pack 10, which includes: a box body 100, a box cover 200, a waterproof and breathable valve 300 and a plurality of battery packs 400.

[0033] The box body 100 is used to accommodate the battery pack 400, the box cover 200 is arranged on the opening side of the box body 100, a gap is arranged between the battery pack 400 and the box cover 200, and the waterproof breathable valve 300 is arranged on the box cover 200;

[0034] See also Figure 3 , Figure 4 and Figure 5 , wherein the waterproof breathable valve 300 includes a valve body 310, a valve core 320, a spring 330 and a material box 340, the valve body 310 is provided with a pressure relief chamber 311, an exhaust channel 312 and a through hole 313, the through hole 313 is used to connect the exhaust channel 312 and the pressure relief chamber 311, the valve core 320 is located in the pressure relief chamber 311, a first sealing ring 510 is provided at a position where the valve core 320 contacts the pressure relief chamber 311, the spring 330 is used to make the valve core 320 abut against the first sealing ring 510, and the material box 340 is provided on the valve body 310;

[0035] The material box 340 is filled with a flame retardant, and when high-pressure gas flows through the exhaust passage 312 , the flame retardant in the material box 340 is drawn into the exhaust passage 312 .

[0036] See also Figure 5 The waterproof breathable valve 300 is located on the box cover 200. When the battery pack 400 in the box body 100 is charged and discharged normally, the valve core 320 is pressed on the first sealing ring 510 by the spring 330, and the exhaust channel 312 and the pressure relief chamber 311 are separated. In this state, the gas in the box body 100 needs to pass through the exhaust channel 312 and the through hole 313 to enter the valve core 320 and be discharged outward through the valve core 320. While meeting the balance of the air pressure inside and outside the box body 100, it prevents external dust and moisture from entering the box body 100, thereby providing protection for the battery pack 400.

[0037] See also Figure 6When the battery pack 400 in the box body 100 is abnormally charged and discharged, and the pressure in the box body 100 is too high, the spring 330 is compressed and contracted, and the valve core 320 rises under the action of air pressure. Since the valve core 320 is separated from the first sealing ring 510, the exhaust channel 312 is connected to the pressure relief chamber 311. In this state, the gas in the box body 100 directly passes through the through hole 313 into the pressure relief chamber 311 and is discharged outward, without the need for ventilation through the valve core 320, thereby achieving the purpose of rapid pressure relief.

[0038] Thermal runaway is likely to occur when the battery pack 400 is abnormally charged and discharged. When the battery pack 400 catches fire due to thermal runaway, the valve core 320 will also be lifted up by the air pressure to cause the waterproof breathable valve 300 to quickly release pressure. Since the gas in the box body 100 is directly ejected outward quickly in this state, the exhausted gas is likely to carry flames and ignite other electronic accessories outside the box body 100. Therefore, a material box 340 is also provided on the waterproof breathable valve 300. When the high-pressure gas is discharged, the gas flow rate at the exhaust channel 312 is fast to form a negative pressure, thereby bringing out the flame retardant particles in the material box 340, and using the flame retardant to extinguish the sparks entrained by the high-pressure gas, thereby avoiding direct ignition of electronic accessories outside the battery pack during pressure release.

[0039] It should be noted that, when the battery pack 400 has thermal runaway, the negative pressure generated when the high-pressure gas passes through the exhaust channel 312 can be used to remove the flame retardant in the material box 340, but the flame retardant needs to contact with the sparks in the gas to absorb heat and extinguish it. The flame retardant entering the exhaust channel 312 may not be able to just contact with the sparks. Therefore, there is still a probability that the sparks will be ejected outward with the gas during pressure relief. In order to solve the above problem, the waterproof breathable valve 300 is further improved as follows:

[0040] See also Figure 5 and Figure 6 The waterproof breathable valve 300 further includes a feeding sleeve 350, which is embedded in the inner wall of the exhaust channel 312. A spiral pipe 351 is provided at the contact point between the feeding sleeve 350 and the inner wall of the exhaust channel 312. The spiral pipe 351 is connected to the material box 340, and the spiral pipe 351 extends from a side close to the material box 340 toward the position of the through hole 313;

[0041] A convex ring 352 is provided on the inner wall of the feeding sleeve 350. The convex ring 352 is located at one end of the feeding sleeve 350 close to the through hole 313. The convex ring 352 narrows the exhaust channel 312. A plurality of delivery holes 353 are opened on the convex ring 352. The delivery holes 353 are used to connect the exhaust channel 312 and the spiral pipe 351.

[0042] The starting position and the ending position of the protruding ring 352 are both provided with chamfers 3521 , and the delivery hole 353 is located on the chamfers 3521 .

[0043] It should be emphasized that one end of the spiral pipe 351 is connected to the material box 340, and the other end is connected to the exhaust channel 312 through the delivery hole 353. Since the diameter of the exhaust channel 312 is much smaller than the cross-sectional area of ​​the box 100, when the high-pressure gas passes through the exhaust channel 312, the pressure in the exhaust channel 312 is lower than the pressure in the box 100, and a convex ring 352 is provided on the inner wall of the feeding sleeve 350, so that the exhaust channel 312 becomes narrower, and the flow rate of the gas will become faster when passing through the convex ring 352. Based on the Bernoulli principle, the pressure is small where the flow rate is fast, that is, the pressure at the position of the convex ring 352 in the exhaust channel 312 is relatively smaller than that in other areas, so that the pressure at this position is closer to the box 100. 0 forms a pressure difference, and the delivery holes 353 are distributed on the chamfers 3521 of the convex ring 352. The flame retardant is discharged from the delivery holes 353 under the action of the pressure difference. The flame retardant needs to pass through the spiral pipe 351 when being discharged. When the flame retardant enters the exhaust channel 312, it is obliquely injected into the exhaust channel 312 under the action of inertia. There are multiple delivery holes 353, and multiple delivery holes 353 simultaneously deliver flame retardants into the exhaust channel 312, thereby disrupting the airflow direction in the exhaust channel 312, so that the flame retardant can be more evenly distributed in the exhaust channel 312, thereby increasing the probability of the flame retardant contacting with sparks in the gas, thereby preventing sparks from being ejected outward with the gas.

[0044] Furthermore, the discharge of the flame retardant utilizes the pressure difference formed at the convex ring 352, and there is no need to configure an additional electronic control system, which simplifies the structure of the waterproof breathable valve 300. Compared with the electronic control system, the advantage of the flame retardant is that the release of the flame retardant does not require electricity. When thermal runaway causes the entire vehicle to lose power, the flame retardant can also be released smoothly.

[0045] It should be noted that the thermal runaway of the battery pack 400 is a continuous process. The existing waterproof and breathable valve will close again after the air pressure in the box 100 drops. At this time, the thermal runaway of the battery pack 400 has not stopped. The air pressure has dropped, but the heat has not fully returned to normal. Under the influence of high temperature, the originally out-of-control battery pack 400 continues to be in a thermal runaway state, and the air pressure in the box 100 will rise again. The other normal battery packs 400 in the box 100 are in a high temperature and high pressure environment for a long time, inducing thermal runaway of other battery packs 400.

[0046] See also Figure 2 , Figure 3 and Figure 5 To solve the above problem, the valve core 320 is provided with a ventilation hole 321 and a ventilation chamber 322. The ventilation hole 321 faces the through hole 313. A breathable membrane 323 and a cover 324 are provided in the ventilation chamber 322. A notch 3241 communicating with the pressure relief chamber 311 is provided on the cover 324.

[0047] The waterproof breathable valve 300 further includes a delayed sealing component 600, which includes an outer ring 610, a guide plate 620 and a plurality of deformable buckles 630. The guide plate 620 is disposed on the cover 324. A gap is provided between the outer wall of the guide plate 620 and the inner wall of the pressure relief chamber 311. The deformable buckle 630 includes a memory metal sheet 631 and a heat conducting block 632. The heat conducting block 632 is welded to the guide plate 620. The memory metal sheet 631 is vertical.

[0048] The outer ring 610 is disposed on the valve body 310 , and a slot 611 matching with the memory metal sheet 631 is formed on the surface of the outer ring 610 .

[0049] The deformation buckles 630 are distributed in a circular array with the axis of the guide plate 620 as the center.

[0050] The heat conductive block 632 separates the memory metal sheet 631 and the guide plate 620 .

[0051] It should be noted that the delayed closure assembly 600 only works when the battery pack 400 thermally runs away, specifically as follows: in the thermal runaway state, the high-temperature gas is directly discharged through the pressure relief chamber 311, and the guide plate 620 is located in the pressure relief chamber 311. When the gas is discharged, the heat will be transferred to the guide plate 620, and the heat accumulated on the guide plate 620 will be transferred to the memory metal sheet 631 through the heat conductive block 632. The heated memory metal sheet 631 bends, and the bent part of the memory metal sheet 631 is buckled into the slot 611. Multiple memory metal sheets 631 cooperate to hook the outer ring 610 to overcome the elastic force of the spring 330, so that the valve core 320 cannot fall. Since the deformation of the memory metal sheet 631 is triggered by temperature, the memory metal sheet 631 will only change from a bent shape to a vertical shape again after the temperature drops. Therefore, even if the air pressure in the box 100 drops briefly, the valve core 320 will not return to its original position, thereby avoiding the sealed environment from further inducing thermal runaway of the battery pack 400.

[0052] See also Figure 3 and Figure 5 In one embodiment, the waterproof breathable valve 300 further includes a nut 360, and an external thread matching the nut 360 is provided on the outer wall of the valve body 310. A second sealing ring 520 is provided on the position of the valve body 310 in contact with the box cover 200. The nut 360 cooperates with the valve body 310 to clamp the box cover 200, and when the nut 360 is tightened, the second sealing ring 520 can be compacted to improve the air tightness of the battery pack.

[0053] See also Figure 5In one embodiment, the valve body 310 is provided with a sleeve 314, the spring 330 is located in the sleeve 314, the valve core 320 is provided with a center rod 325 matching the sleeve 314, the end of the center rod 325 is provided with a stop ring 326, the center rod 325 passes through the sleeve 314, and the spring 330 abuts against the stop ring 326. The stop ring 326 limits the rising height of the valve core 320 to prevent the valve core 320 from falling off, thereby improving the structural stability of the waterproof breathable valve 300.

[0054] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A highly safe lithium battery pack, characterized in that: include: Box body, box cover, waterproof and breathable valve and several battery packs; The box body is used to accommodate the battery pack, the box cover is arranged on the opening side of the box body, a space is arranged between the battery pack and the box cover, and the waterproof and breathable valve is arranged on the box cover; The waterproof breathable valve comprises a valve body, a valve core, a spring and a material box, the valve body is provided with a pressure relief chamber, an exhaust passage and a through hole, the through hole is used to connect the exhaust passage and the pressure relief chamber, the valve core is located in the pressure relief chamber, a first sealing ring is provided at a position where the valve core contacts the pressure relief chamber, the spring is used to make the valve core abut against the first sealing ring, and the material box is provided on the valve body; The material box is filled with a flame retardant, and when high-pressure gas flows through the exhaust channel, the flame retardant in the material box is drawn into the exhaust channel.

2. The high-safety lithium battery pack according to claim 1, characterized in that: The waterproof breathable valve further includes a feeding sleeve, the feeding sleeve is embedded on the inner wall of the exhaust channel, a spiral pipe is provided on the feeding sleeve at a position in contact with the inner wall of the exhaust channel, the spiral pipe is communicated with the material box, and the spiral pipe extends from a side close to the material box toward the position of the through hole; A convex ring is provided on the inner wall of the feeding sleeve, and the convex ring is located on one end of the feeding sleeve close to the through hole. The convex ring narrows the exhaust channel. A plurality of delivery holes are opened on the convex ring, and the delivery holes are used to connect the exhaust channel and the spiral pipe.

3. The high-safety lithium battery pack according to claim 2, characterized in that: The starting position and the ending position of the convex ring are both provided with chamfers, and the delivery hole is located on the chamfers.

4. The high-safety lithium battery pack according to claim 1, characterized in that: The valve core is provided with a ventilation hole and a ventilation chamber, wherein the ventilation hole faces the through hole, a breathable membrane and a sealing cover are provided in the ventilation chamber, and a notch communicating with the pressure relief chamber is provided on the sealing cover.

5. The high-safety lithium battery pack according to claim 4, characterized in that: The waterproof breathable valve further includes a delayed sealing component, which includes an outer ring, a guide plate and a plurality of deformation buckles, wherein the guide plate is arranged on the cover, and a gap is arranged between the outer wall of the guide plate and the inner wall of the pressure relief chamber, and the deformation buckle includes a memory metal sheet and a heat conductive block, wherein the heat conductive block is welded on the guide plate, and the memory metal sheet is vertical; The outer ring is arranged on the valve body, and a groove matching with the memory metal sheet is opened on the surface of the outer ring.

6. The high-safety lithium battery pack according to claim 5, characterized in that: The deformation buckles are distributed in a circular array with the axis of the guide disk as the center.

7. The high-safety lithium battery pack according to claim 5, characterized in that: The heat conductive block separates the memory metal sheet and the guide plate.

8. The high-safety lithium battery pack according to claim 1, characterized in that: The waterproof breathable valve also includes a nut, and the outer wall of the valve body is provided with an external thread matching the nut.

9. The high-safety lithium battery pack according to claim 1, characterized in that: The valve body is provided with a sleeve, the spring is located in the sleeve, the valve core is provided with a center rod matching the sleeve, a stop ring is provided at the end of the center rod, the center rod passes through the sleeve, and the spring is abutted against the stop ring.

10. The high-safety lithium battery pack according to claim 1, characterized in that: A second sealing ring is provided on the valve body at a position in contact with the box cover.

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