CN218939938U

CN218939938U - Explosion-proof valve structure

Info

Publication number: CN218939938U
Application number: CN202223170157.8U
Authority: CN
Inventors: 王从周
Original assignee: Hefei Guoxuan High Tech Power Energy Co Ltd
Current assignee: Hefei Gotion High Tech Power Energy Co Ltd
Priority date: 2022-11-28
Filing date: 2022-11-28
Publication date: 2023-04-28
Anticipated expiration: 2032-11-28

Abstract

The utility model discloses an explosion-proof valve structure, and belongs to the field of lithium ion battery manufacturing. The utility model comprises a cover plate and a liquid injection hole, wherein: the cover plate is used for sealing the opening of the lithium ion battery shell; the cover plate is provided with a liquid injection hole penetrating through the cover plate; in order to seal the liquid injection hole and prevent electrolyte in the battery from leaking out, a plurality of nail holes penetrating through the cover plate are formed in the cover plate, and the nail holes are uniformly distributed around the liquid injection hole; the support piece is positioned on the outer side of the cover plate and is connected with the soft envelope; a step structure is arranged on one side surface of the support piece, which is far away from the cover plate, the step structure is positioned on one side, which is close to the liquid injection hole, and a through hole penetrating through the support piece is arranged on the step surface; the through holes are in one-to-one correspondence with the nail holes so as to penetrate through the connecting piece; and the connecting piece penetrates through the nail holes and the through holes and connects the supporting piece with the cover plate. The utility model is mainly used for avoiding explosion caused by thermal runaway of the lithium ion battery.

Description

Explosion-proof valve structure

Technical Field

The utility model relates to the field of lithium ion battery manufacturing, in particular to an explosion-proof valve structure.

Background

Lithium ion batteries are known as a green chemical energy source in the 21 st century, and are widely applied to various fields such as 3C consumer electronics, power batteries, energy storage and the like. With the development of battery technology, the energy density of lithium ion batteries is higher and higher, and the safety problem of lithium ion batteries is also more and more prominent. Once thermal runaway occurs in the square lithium ion battery, the internal temperature of the square lithium ion battery is rapidly increased, the internal pressure of the square lithium ion battery is rapidly increased, explosion is very easy to occur, and great potential safety hazards are caused.

Compared with square lithium ion batteries such as traditional steel shells and aluminum shells, the battery core shape can be any shape, when the battery core is expanded, the soft lithium ion battery generally expands and cracks, explosion is not easy to occur, the square lithium ion battery such as the traditional steel shells and aluminum shells is easier to explode, but the soft lithium ion battery is irregular in shape and is unfavorable for combined use among batteries. If the square battery adopts a soft package similar mode to release pressure, the explosion risk can be reduced to a certain extent. In addition, the traditional square battery liquid injection is generally carried out through reserved liquid injection Kong Zhuye, and the liquid injection hole is sealed through laser welding after liquid injection is completed. In the production process, the liquid injection hole is easy to be polluted by electrolyte, the polluted liquid injection hole is not easy to clean, the polluted liquid injection hole is easy to generate a frying point during laser welding, poor welding is caused, and then the cell is scrapped, so that the production cost is greatly increased.

The search finds that a Chinese patent with the name of 'large-capacity lithium ion battery aluminum membrane type explosion-proof valve' applied in 2011, 09 and 29 days is disclosed as follows: CN 202308122U. The patent discloses an aluminum film type explosion-proof valve of a high-capacity lithium ion battery, which comprises an explosion-proof valve base, an explosion-proof valve nut, an explosion-proof valve film, an upper anti-corrosion rubber ring and a lower anti-corrosion rubber ring; the inner cavity of the explosion-proof valve base is provided with a step table, the step table is sequentially provided with the lower anti-corrosion rubber ring, the explosion-proof valve membrane and the upper anti-corrosion rubber ring, and the explosion-proof valve nut and the explosion-proof valve base are connected into a whole in a threaded manner. The scheme is provided with the explosion-proof base and the explosion-proof nut, but the whole structure is of a rigid structure, and explosion can still occur when the internal air pressure of the lithium ion battery is too high.

Disclosure of Invention

1. Technical problem to be solved by the utility model

In view of the problems that the shells of the conventional square lithium battery are mostly of rigid structures such as steel shells or aluminum shells, the internal pressure is increased after thermal runaway occurs in the lithium ion battery, and explosion of the lithium ion battery is easy to occur, the soft-package battery sealing cover structure is added to the rigid lithium ion battery shell, and the problem of explosion of the lithium ion battery is avoided.

2. Technical proposal

In order to achieve the above purpose, the technical scheme provided by the utility model is as follows: an explosion-proof valve structure is provided, including apron and notes liquid hole, wherein: the cover plate is used for sealing the opening of the lithium ion battery shell and is communicated through the liquid injection hole; the liquid injection hole can be used for conducting pressure and can also be used for injecting liquid:

in order to seal the liquid injection hole and prevent electrolyte in the battery from leaking out, a plurality of nail holes penetrating through the cover plate are formed in the cover plate, and the nail holes are uniformly distributed around the liquid injection hole; the support piece is positioned on the outer side of the cover plate and is connected with the soft envelope; an annular step structure is arranged on one side surface of the support piece, which is far away from the cover plate, the step structure is positioned on the annular surface on one side, which is close to the liquid injection hole, and a through hole penetrating the support piece is formed in the step surface; the through holes are in one-to-one correspondence with the nail holes so as to allow the connecting piece to pass through; the connecting piece penetrates through the nail hole and the through hole, the supporting piece is tightly connected with the cover plate, the supporting piece and the cover plate are fixedly connected through the connecting piece, and the stability of the whole structure is guaranteed.

In order to realize complete coverage of the soft coating, the support piece is of an annular structure surrounding the liquid injection hole, and the soft coating is fixed on the upper surface of the step of the highest layer of the support piece through heat sealing, so that electrolyte is prevented from leaking out.

In order to further fix the support piece on the cover plate, the connecting piece is an annular sealing nail, and one end of the connecting piece penetrating through the support piece and the cover plate is an expansion plate. The expansion plate expands along the surface of the support piece or the cover plate, so that the support piece is prevented from loosening or falling off.

In order to prevent electrolyte from overflowing outwards from between the cover plate and the supporting piece, a sealing ring is arranged between the cover plate and the supporting piece and is positioned on one side of the connecting piece away from the liquid injection hole.

In order to enable the soft film to have certain impact resistance and facilitate heat sealing, the soft film is an aluminum plastic film, and the aluminum plastic film comprises a three-layer structure, and is sequentially provided with a protective layer, an aluminum layer and a heat sealing layer from outside to inside.

In order to reduce the total weight of the lithium ion battery and facilitate heat sealing, the support piece is made of polyethylene or polypropylene.

3. Advantageous effects

Compared with the prior art, the technical scheme provided by the utility model has the following beneficial effects:

(1) Once thermal runaway occurs in the square lithium ion battery such as the existing steel shell, aluminum shell and the like, the internal temperature rises rapidly, the internal pressure of the battery increases rapidly, and when the internal pressure increases to a limit, the lithium ion battery can explode, so that great potential safety hazards are caused. The utility model provides an explosion-proof valve structure on the basis of keeping square structures of the conventional square lithium ion batteries such as a steel shell, an aluminum shell and the like, and when the internal pressure of the lithium ion battery is increased, the explosion-proof valve structure provided by the utility model can expand and crack, so that the internal pressure of the lithium ion battery is released, and the explosion of the lithium ion battery caused by thermal runaway is avoided.

(2) The existing square battery liquid injection is generally carried out through reserved liquid injection Kong Zhuye, and a liquid injection hole is sealed through laser welding after liquid injection is completed. In the actual liquid injection process, the liquid injection hole is easy to be polluted by electrolyte, the polluted liquid injection hole is difficult to clean, the polluted liquid injection hole is easy to generate a frying point during laser welding, poor welding is caused, the cell is scrapped, and the production cost is increased. The explosion-proof valve structure provided by the utility model can be used as a liquid injection hole in the liquid injection process, laser welding is not needed to be sealed after liquid injection is completed, the liquid injection hole can be sealed only by heat sealing, the yield of products can be improved, and the production cost is saved.

Drawings

FIG. 1 is a schematic side view of the present utility model;

fig. 2 is a top view of the present utility model.

Description of the reference numerals: 1. a cover plate; 2. a support; 3. a connecting piece; 4. a seal ring; 5. a liquid injection hole; 6. soft coating; 7. and a sealing part.

Detailed Description

For a further understanding of the present utility model, the present utility model will be described in detail with reference to the drawings and examples.

Examples

Once thermal runaway occurs in the square lithium ion battery, the internal temperature of the square lithium ion battery can be rapidly increased, the internal pressure of the square lithium ion battery can be rapidly increased, explosion is very easy to occur, and great potential safety hazards are caused. The soft-package lithium ion battery generally expands and cracks when the inside of the battery core expands, so that the internal pressure is released, and explosion is not easy to occur. However, the soft package lithium ion battery has irregular appearance, which is unfavorable for the combination use among batteries. If the square battery adopts a soft package similar mode to release pressure, the explosion risk can be reduced to a certain extent and the square battery is convenient to use. Therefore, as shown in fig. 1 and 2, the present embodiment provides an explosion-proof valve structure, which includes a cover plate 1 and a liquid injection hole 5, wherein the cover plate 1 is used for sealing an opening of a lithium ion battery shell, protecting the lithium ion battery from damage caused by external impact to an internal battery core.

In this embodiment, the side of the cover plate 1 contacting the electrolyte is the inner side, and the side contacting the support 2 is the outer side. In order to allow the internal gas pressure of the lithium ion battery to diffuse outward when the lithium ion battery thermally expands, the liquid injection hole 5 of the present embodiment penetrates the cover plate 1. Because the surface of the cover plate 1 is inconvenient to directly encapsulate the liquid injection hole 5, as shown in fig. 1, the support member 2 is disposed on the outer side of the cover plate 1 in this embodiment, and is used for supporting the soft capsule 6 sealed to the liquid injection hole 5.

The utility model seals the liquid injection hole 5 by adopting the soft coating 6, but can still protect the internal structure of the battery. The soft coating 6 provided by the utility model is an aluminum plastic film, and the aluminum plastic film comprises a three-layer structure, and is sequentially provided with a protective layer, an aluminum layer and a heat sealing layer from outside to inside. The inner layer is a heat sealing layer, and is made of polypropylene material, so that the sealing and bonding effects are achieved; the middle layer is aluminum foil, so that the infiltration of water vapor outside the battery can be prevented, and meanwhile, the seepage of an internal electrolyte is prevented; the outer layer is a protective layer, adopts a nylon material with high melting point, has strong mechanical property, prevents the damage of external force to the battery, and plays a role in protecting the battery.

The aluminum plastic film provided by the utility model has good isolation effect, and the common electrolyte for the lithium ion battery is a plurality of carbonate organic solvents and lithium hexafluorophosphate, wherein the lithium hexafluorophosphate is sensitive to moisture, and can react once contacting with the moisture, so that the battery produces gas, swells, has serious cycle attenuation and the like. The aluminum plastic film provided by the utility model has good barrier property, can realize sealing on electrolyte under the condition of perfect heat sealing, and can isolate the entry of moisture and oxygen in air, and the good barrier effect of the aluminum plastic film can keep the long-term stability of the lithium battery without being influenced by the water and oxygen in air.

The aluminum plastic film provided by the utility model can also resist corrosion of electrolyte, and various organic solvents in the electrolyte can generally swell and dissolve the flexible packaging material, so that the bonding effect between the composite layers is destroyed, the concentration ratio of components in the electrolyte is changed, and the electrical performance of a battery is further influenced. Wherein hydrofluoric acid generated by electrolyte decomposition will severely corrode the aluminum foil, thereby damaging the entire battery pack. The polypropylene of the inner layer of the aluminum plastic film provided by the utility model has excellent chemical stability, can be contacted with the electrolyte with strong corrosiveness for a long time without chemical reaction, and ensures the long-term stability of chemical components of the electrolyte. Therefore, the aluminum plastic film provided by the utility model improves the stability of the battery and prolongs the service life of the battery.

In this embodiment, in order to seal the liquid injection hole 5 and reduce the overall weight of the lithium ion battery, the support member 2 is made of polyethylene or polypropylene. The soft envelope 6 is fixed to the upper surface of the step of the uppermost layer of the support 2 by heat sealing. The heat-sealing method used in this example is: the surface of the heat sealing layer of the aluminum plastic film is hot-pressed for a certain time by using a heated metal block, so that the surface is melted, and then the surface is pressed on the support piece 2, so that the aluminum plastic film and the support piece 2 are fused together to form a sealing part 7, and the leakage of electrolyte is avoided.

In this embodiment, the liquid injection hole 5 is cylindrical, so as to seal the liquid injection hole 5, as shown in fig. 2, the support 2 provided by the present utility model is an annular structure surrounding the liquid injection hole 5.

In order to facilitate the fixing of the support member 2 and support the soft capsule 6, a step structure is formed on a side surface of the support member 2 away from the cover plate 1 in this embodiment, and in order to avoid the leakage of the liquid outward from the through hole, the step structure is located on a side close to the liquid injection hole 5 in this embodiment. In order to fix the support 2 on the cover plate 1, a through hole penetrating through the support 2 is arranged on the step surface, a plurality of nail holes penetrating through the cover plate 1 are arranged on the cover plate 1, and the through holes are in one-to-one correspondence with the nail holes and are used for penetrating through the connecting piece 3. In order to make the stress of the fixing connector 3 uniform, the nail holes in this embodiment are uniformly distributed around the liquid injection hole 5.

The connecting piece 3 provided by the utility model penetrates through the nail holes and the through holes to connect the supporting piece 2 with the cover plate 1. Wherein, connecting piece 3 is annular sealing nail, and connecting piece 3 passes support piece 2 and apron 1's one end and is the expansion board, and the structure of expansion board can firmly fix support piece 2 and apron 1, can not take place the relative slip.

In order to avoid the leakage of the annular sealing nails to the outside at the joint of the cover plate 1, a sealing ring 4 is arranged between the cover plate 1 and the support piece 2, the sealing ring 4 is positioned at one side of the connecting piece 3 far away from the liquid injection hole 5, and even if electrolyte flows to the joint of the support piece 2 and the cover plate 1 through the nail holes on the cover plate 1, the electrolyte cannot overflow to the outside, so that the electrolyte is reduced.

The utility model and its embodiments have been described above by way of illustration and not limitation, and the utility model is illustrated in the accompanying drawings and described in the drawings in which the actual structure is not limited thereto. Therefore, if one of ordinary skill in the art is informed by this disclosure, the structural mode and the embodiments similar to the technical scheme are not creatively designed without departing from the gist of the present utility model.

Claims

1. The utility model provides an explosion-proof valve structure, includes apron (1) and annotates liquid hole (5), its characterized in that:

the cover plate (1) is used for sealing the opening of the lithium ion battery shell, and the cover plate (1) is communicated through the liquid injection hole (5);

the cover plate (1) is provided with a plurality of nail holes penetrating through the cover plate (1), and the nail holes are uniformly distributed around the liquid injection holes (5);

the support piece (2) is positioned at the outer side of the cover plate (1) and is connected with the soft coating film (6); an annular step structure is arranged on one side surface of the support piece (2) far away from the cover plate (1), the step structure is positioned on an annular surface on one side close to the liquid injection hole (5), and a through hole penetrating through the support piece (2) is formed in the step surface; the through holes are in one-to-one correspondence with the nail holes so as to allow the connecting piece (3) to pass through;

and the connecting piece (3) penetrates through the nail holes and the through holes and tightly connects the supporting piece (2) with the cover plate (1).

2. An explosion-proof valve structure according to claim 1, wherein: the support (2) is of an annular structure surrounding the liquid injection hole (5).

3. An explosion-proof valve structure according to claim 1 or 2, characterized in that: the connecting piece (3) is an annular sealing nail, and one end of the connecting piece (3) penetrating through the supporting piece (2) and the cover plate (1) is an expansion plate.

4. An explosion-proof valve structure according to claim 1, wherein: the soft coating film (6) is fixed on the upper surface of the step of the highest layer of the supporting piece (2) through heat sealing, so that electrolyte leakage is avoided.

5. An explosion-proof valve structure according to claim 1 or 2, characterized in that: a sealing ring (4) is arranged between the cover plate (1) and the supporting piece (2), and the sealing ring (4) is positioned on one side, far away from the liquid injection hole (5), of the connecting piece (3).

6. An explosion-proof valve structure according to claim 1 or 4, characterized in that: the soft coating (6) is an aluminum plastic film, and the aluminum plastic film comprises a three-layer structure, and is sequentially provided with a protective layer, an aluminum layer and a heat sealing layer from outside to inside.

7. An explosion-proof valve structure according to claim 1 or 2, characterized in that: the supporting piece (2) is made of polyethylene or polypropylene.