Patent Application
20240413426
The present invention relates to an endothermic pouch assembly capable of suppressing a heat propagation phenomenon that causes other nearby secondary cells to continuously overheat in the event of a thermal runaway.
This application claims the benefit of priority based on Korean Patent Applications No. 10-2022-0071856, filed Jun. 14, 2022, the disclosure of which is incorporated herein by reference in its entirety.
Unlike primary batteries, secondary batteries can be recharged, and they have been heavily researched and developed in recent years due to their potential for miniaturization and large capacity. The demand for secondary batteries as an energy source is increasing rapidly due to the technological development and increasing demand for mobile devices, electric vehicles, and energy storage systems, which are emerging in response to the need for environmental protection.
Secondary batteries are categorized into coin-type cells, cylindrical cells, prismatic cells, and pouch-type cells based on the shape of the cell case. In a secondary battery, an electrode assembly mounted inside the battery case is a charge and dischargeable power generator consisting of a laminated structure of electrodes and separators.
Since secondary batteries are required to be used continuously for a long period of time, it is necessary to effectively control the heat generated during the charging and discharging process. If the secondary battery is not properly cooled, the increase in temperature will cause an increase in current, and the increase in current will cause another increase in temperature, resulting in a feedback chain reaction that will eventually lead to the catastrophic condition of thermal runaway.
In addition, if the secondary batteries are grouped together in the form of modules or packs, a thermal propagation phenomenon occurs in which the thermal runaway of one secondary battery continuously overheats the other secondary batteries in the vicinity. Furthermore, there is a high risk of fire due to flammable gases emitted from overheated secondary batteries and ignition sources such as heated electrodes, so it is necessary to suppress this ignition risk.
The present invention aims to provide an endothermic pouch assembly that can effectively suppress and prevent the phenomenon of heat propagation due to thermal runaway generated in a secondary battery.
In addition, the present invention aims to enable endothermic pouches, which are difficult to maintain their shape, to be placed in the correct position and size between the secondary batteries.
However, the technical problems that the present invention seeks to solve are not limited to those described above, and other problems not mentioned will be apparent to one of ordinary skill in the art from the following description of the invention.
The present invention relates to an endothermic pouch assembly, which in one example includes an endothermic pouch with liquid-impregnated absorbent material sealed inside and a heat-fusion sealing portion formed along a rim of the endothermic pouch, and a pouch cartridge including a pair of rim frames that bind the heat-fusion sealing portion of the endothermic pouch at opposite sides of the endothermic pouch.
In one exemplary embodiment of the present invention, the heat-fusion sealing portion is provided with a first vulnerable portion having a lower bursting strength than a remainder of the heat-fusion sealing portion, and the rim frame is provided with a venting induction hole aligned with the first vulnerable portion.
In addition, the pouch cartridge may expose a surface of the endothermic pouch in an interior region of the rim frame.
In addition, the endothermic pouch may be provided with a second vulnerable portion having a lower bursting strength than a remainder of the heat-fusion sealing portion, the second vulnerable portion on a surface of the endothermic pouch not covered by the pouch cartridge.
For example, the second vulnerable portion may be located directly inside the pouch cartridge at a location of the venting induction hole.
In one exemplary embodiment of the present invention, the absorbent material may be a superabsorbent matrix including a superabsorbent polymer (SAP) or superabsorbent fiber (SAF).
In addition, the liquid is water mixed with additives, and the additive may be a substance that lowers the surface tension of water, or is a fire extinguishing agent.
In addition, the liquid impregnated in the superabsorbent matrix absorbs heat, causing a phase change to gas, and when the pressure of the gas exceeds the bursting strength of the first vulnerable portion, the first vulnerable portion fractures, allowing gas inside the endothermic pouch to be inductively ejected through the venting induction hole.
In an example, the bursting strength of the second vulnerable portion may be higher than the bursting strength of the first vulnerable portion.
Meanwhile, in another exemplary embodiment of the present invention, the heat-fusion sealing portion of the endothermic pouch is provided with at least one guide hole, and at least one of the pair of rim frames may be provided with a projection that inserts into the at least one guide hole.
Here, the endothermic pouch and the rim frame may be mutually aligned by an insertion of the projection of the rim frame into the at least one guide hole of the endothermic pouch.
In addition, the pair of rim frames are each equipped with a pair of hooks, respectively, and the pair of rim frames may be bound together by the engagement of the pair of hooks.
In addition, the heat-fusion sealing portion of the endothermic pouch may have an incision formed in a position corresponding to the pair of hooks.
According to the endothermic pouch assembly of the present invention with the above configuration, the endothermic pouch can quickly absorb and dissipate heat in environments with high temperature rise, such as rapid charging, to suppress the occurrence of thermal runaway, and maintain performance and life without high temperature rise.
In addition, when a thermal runaway phenomenon occurs in a secondary battery, the liquid impregnated with the absorbent material in the endothermic pouch absorbs heat and vaporizes, and when the vaporized gas rises above a certain pressure, it breaks the endothermic pouch and erupts, thereby greatly reducing the risk of fire by cooling the combustible gas emitted from the overheated battery cell and the ignition source such as heated electrodes and suppressing the flame.
Further, the endothermic pouch assembly of the present invention includes a pouch cartridge that binds against the heat-fusion sealing portion of the endothermic pouch to maintain a specific shape, thereby enabling the endothermic pouch to be positioned between the secondary cells in a precise location and size.
In addition, the venting induction holes provided in the pouch cartridge can accurately induce the emitting direction of the gas generated inside the endothermic pouch, thereby more effectively suppressing the risk of fire.
However, the technical effects of the present invention are not limited to those described above, and other effects not mentioned will be apparent to one of ordinary skill in the art from the following description of the invention.
The following drawings accompanying this specification illustrate preferred exemplary embodiments of the present invention and are intended to serve as a further understanding of the technical ideas of the present invention in conjunction with the detailed description of the invention that follows, so the present invention is not to be construed as limited to what is shown in such drawings.
The present invention is subject to various modifications and can have many embodiments, certain of which are described in detail below.
However, this is not intended to limit the invention to any particular embodiment and is to be understood to include all modifications, equivalents, or substitutions that fall within the scope of the thought and skill of the present invention.
In the present invention, the terms “include” or “have” and the like are intended to designate the presence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification and are not to be understood as precluding the possibility of the presence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.
Also, in the present invention, when a layer, membrane, region, plate, etc. is described as being “on top of” another, this includes not only when it is “directly above” another, but also when there is another part in between. Conversely, when a layer, membrane, area, plate, etc. is described as being “under” another part, this includes not only when it is “directly under” another part, but also when there is another part in between. Also, in the present application, references to being disposed “on top of” may include not only being disposed on top, but also being disposed on the bottom.
The present invention relates to an endothermic pouch assembly, which in one example includes an endothermic pouch and a pouch cartridge that binds to the endothermic pouch.
The endothermic pouch is a sealed container of liquid-impregnated absorbent material that is placed in contact with the surface of a secondary battery so that the liquid inside absorbs heat from the secondary battery.
The pouch cartridge includes a pair of rim frames that bind at both sides a heat-fusion sealing portion formed along the rim of the endothermic pouch. While the nature of the pouch, which is typically made of laminated sheet material, makes it difficult to maintain a specific shape, the pouch cartridge, which is made of metal or synthetic resin material, wraps around the rim of the endothermic pouch, thereby stabilizing the shape of the entire endothermic pouch assembly. Thus, the endothermic pouch assembly of the present invention ensures that the endothermic pouch is disposed between the secondary batteries in the precise position and size.
Further, the endothermic pouch assembly of the present invention is provided with a first vulnerable portion having a relatively low bursting strength on a heat-fusion sealing portion of the endothermic pouch, and a rim frame of the pouch cartridge is provided with a venting induction hole in a region corresponding to the first vulnerable portion.
Therefore, the venting induction holes provided in the pouch cartridge can accurately guide the emitting direction of the gas generated inside the endothermic pouch, thereby avoiding high-heat gases or parts that are vulnerable to flame, and more effectively suppressing the risk of fire.
Hereinafter, specific embodiments of the present invention will be described in detail with reference to the accompanying drawings. For reference, the directions of front, back, up, down, left, and right used in the following description to designate relative positions are intended to aid in the understanding of the invention, and refer to the directions shown in the drawings unless otherwise specified.
The endothermic pouch assembly 10 of the present invention refers to an assembly where an endothermic pouch 100 and a pouch cartridge 200 are coupled. The endothermic pouch 100 may be manufactured using a flexible laminated sheet, within which a liquid-impregnated absorbent material 110 is sealedly stored.
The pouch cartridge 200 includes a pair of rim frames 210 that bind the heat-fusion sealing portion 120 formed along the rim of the endothermic pouch 100 on both sides. The rim frames 210 may be made of a metal, such as aluminum, or a synthetic resin, such as polycarbonate.
While it is difficult for the endothermic pouch 100 to remain exactly the same shape due to the flexibility of the packaging material, the laminated sheet, the overall shape and size of the endothermic pouch assembly 10 is fairly uniform and structured as the structural element, the rim frame 210, secures the rim of the endothermic pouch 100.
Thus, the endothermic pouch assembly 10 of the present invention ensures that the endothermic pouch 100 is positioned in the precise location and size between the secondary batteries 1000, which in turn facilitates the management of manufacturing tolerances or deviations when configuring a battery module or pack incorporating a plurality of secondary batteries 1000 and the endothermic pouch 100.
In addition, the pouch cartridge 200 exposes a surface of the endothermic pouch 100 at an inner region of the rim frame 210 that binds the endothermic pouch 100 against the heat-fusion sealing portion 120 of the endothermic pouch 100. In other words, the inner region of the rim frame 210 comprises an incised space. This is to maximize the amount of endothermic contact surface that is in direct contact with the surface of the secondary battery 1000 by exposing most of the surface of the endothermic pouch 100, as shown in
The liquid impregnated in large quantities in the absorbent material 110 housed in the endothermic pouch 100 absorbs the heat generated by the secondary battery 1000 and vaporizes when its temperature exceeds its boiling point. Due to the volume increase by the phase change from liquid to gas, the endothermic pouch 100 sealing the absorbent material 110 is subjected to pressure. And, the endothermic pouch 100 has a first vulnerable portion 122 that preferentially fractures when the liquid impregnated in the absorbent material 110 vaporizes, which in turn increases the internal pressure.
The body of the endothermic pouch 100 may be manufactured using a flexible laminated sheet, and the laminated sheet may be a three or more layers structure including an aluminum thin film layer, an inner resin layer formed on an inner side of the aluminum thin film layer, and an outer resin layer formed on an outer side of the aluminum thin film layer. For example, the inner resin layer may be casted polypropylene (CPP) or polypropylene (PP), and the outer resin layer may be polyethylene terephthalate (PET) or nylon.
The first vulnerable portion 122 of the endothermic pouch 100 is configured to preferentially fracture by an increase in internal pressure due to vaporization of the liquid by locally reducing the sealing strength of the heat-fusion sealing portion 120. That is, the first vulnerable portion 122 can be formed in a manner that makes the heat/fusion strength of the heat-fusion sealing portion 120 lower than the surrounding. For example, the first vulnerable portion 122 may be formed by making it less thick than the surrounding area, by forming a notch to reduce the strength, or by locally removing an aluminum thin film layer that maintains durability.
As such, by providing the first vulnerable portion 122 in the endothermic pouch 100, when the secondary battery 1000 overheats due to a thermal runaway phenomenon, the liquid impregnated with the absorbent material 110 in the endothermic pouch 100 absorbs heat and vaporizes, and when the internal pressure of the vaporized gas exceeds a certain pressure, that is, the bursting strength of the first vulnerable portion 122, the first vulnerable portion 122 fractures and ejects gas. The gas ejected from the endothermic pouch 100 greatly reduces the risk of fire by cooling the flammable gas emitted from the overheated secondary battery 1000 and the ignition source such as the heated electrodes, and by suppressing the flame.
And, as shown in
This induction venting is very useful and important for the safety of the battery module or pack. The battery module or pack, as well as the secondary battery 1000 itself, contains electrical components that are vulnerable to heat, flame, moisture, etc. In addition, in vehicles, devices, equipment, etc. in which the battery module/pack is mounted, it is necessary to specify the venting direction to minimize safety accidents such as personal injury. Therefore, the endothermic pouch assembly 10 of the present invention can realize optimal induction venting by appropriately designing the location of the first vulnerable portion 122 and the venting induction hole 220, thereby improving the safety of the secondary battery 1000 and the battery module/pack.
Additionally, the endothermic pouch 100 may be further provided with a second vulnerable portion 130 having a relatively low bursting strength on a surface that is not obscured by the pouch cartridge 200. For example, the second vulnerable portion 130 may be located directly downstream of the venting induction hole 220 and arranged to eject gas proximate to the direction of the induced venting.
The second vulnerable portion 130 may be provided to provide an additional gas outlet, for example, in the event that the ejection of gas through the first vulnerable portion 122 and the venting induction hole 220 is insufficient, or as a safety outlet in the event that the internal pressure of the endothermic pouch 100 rises above a predetermined level. In this regard, the bursting strength of the second vulnerable portion 130 may be set higher than the bursting strength of the first vulnerable portion 122 such that the second vulnerable portion 130 bursts after the first vulnerable portion 122.
Meanwhile, in the first embodiment of the present invention, the absorbent material 110 may be an absorbent material 110 including a superabsorbent matrix, such as a superabsorbent polymer (SAP) or a superabsorbent fiber (SAF). Superabsorbent matrices can be porous or fibrous, capable of absorbing large amounts of liquid by exhibiting capillarity, while superabsorbent fibers can be manufactured in the form of fibers, such as nonwovens, by processing superabsorbent resins.
The specific types of superabsorbent resins and superabsorbent fibers made therefrom are not particularly limited in the present invention, but can be used without restriction as long as they have a high absorption capacity for fluids, in particular water. Examples of superabsorbent resins used in the present invention include one or more selected from the group consisting of polyacrylic acid, polyacrylate, polyacrylate graft polymers, starch, cross-linked carboxymethylated cellulose, acrylic acid copolymers, hydrolyzed starch-acrylonitrile graft copolymers, and starch-acrylic acid graft copolymers, saponified vinyl acetate-acrylic acid ester copolymer, hydrolyzed acrylonitrile copolymer, hydrolyzed acrylamide copolymer, ethylene-maleic anhydride copolymer, isobutylene-maleic anhydride copolymer, polyvinyl sulfonic acid, polyvinyl phosphonic acid, polyvinyl phosphate, polyvinyl sulfuric acid, sulfonated polystyrene, polyvinylamine, polydialkylaminoalkyl (meth)acrylamide, polyethyleneimine, polyallylamine, polyallylguanidine, polydimethyldialylammonium hydroxide, quaternized polystyrene derivatives, guanidine-modified polystyrene, quaternized poly(meth)acrylamide, polyvinylguanidine, and mixtures thereof, and preferably one or more selected from the group consisting of crosslinked polyacrylic acid salts, crosslinked polyacrylic acid, and crosslinked acrylic acid copolymers, but are not limited thereto.
The type of acrylic acid copolymer used as a superabsorbent resin in the present invention is not particularly limited, but may preferably be a copolymer including one or more co-monomers selected from the group consisting of acrylic acid monomer and maleic acid, itaconic acid, acrylamide, 2-acrylamide-2-methylpropanesulfonic acid, 2-(meth)acryloylethanesulfonic acid, 2-hydroxyethyl (meth)acrylate, and styrenesulfonic acid.
In the present invention, the superabsorbent resin may have an absorption capacity for water of 10 g/g to 500 g/g, preferably 50 g/g to 200 g/g, but is not limited thereto. That is, it may absorb 10 g to 500 g, preferably 50 g to 200 g, of water per 1 g of the superabsorbent resin.
In the present invention, a higher amount of absorption of water by the superabsorbent resin can improve the duration of the cooling effect, but when the amount exceeds 500 g/g, the fluidity of the superabsorbent resin increases and it is difficult to maintain its shape, so that effective cooling cannot be exerted, and when the amount is less than 10 g/g, the duration of the cooling effect may be too short to be effective.
In addition, in the first embodiment of the present invention, the liquid impregnating the absorbent material 110 may be water. Water has the largest specific and latent heat among any readily available liquid. Therefore, water impregnated in the absorbent material 110 is suitable for application in the endothermic pouch 100 of the present invention because of the large amount of heat it absorbs during its phase change to gas, beginning even before it is vaporized.
Additionally, the water impregnated in the absorbent material 110 may be mixed with additives that may enhance fire extinguishing capabilities. For example, the additive mixed into the water may be a substance that reduces the surface tension of the water, or may be an extinguishing agent. Substances that reduce the surface tension of water include wetting agents and surfactants, and when the surface tension of water is reduced, the penetration effect of water increases, which enhances the extinguishing effect on ignition sources such as heated electrodes and ignition particles.
Extinguishing agents are agents that extinguish fire by themselves and can include a variety of commercially available powders and liquid extinguishing liquids. For example, an extinguishing agent with the trade name F-500 EA (manufacturer HAZARD CONTROL TECHNOLOGIES, INC.) may be added to water.
Referring to
Accordingly, when the endothermic pouch 100 and the rim frame 210 are mutually coupled, the projection 230 of the rim frame 210 may be inserted into the guide holes 124 of the endothermic pouch 100 so that the endothermic pouch 100 and the rim frame 210 are accurately aligned with each other.
Furthermore, in the first embodiment, the heat-fusion sealing portion 120 of the endothermic pouch 100 is compressed and fixed by a pair of mutually bonded rim frames 210, but in the second embodiment, the projection 230 of the rim frames 210 penetrate the guide holes 124 of the endothermic pouch 100, thereby improving the fixing power of the endothermic pouch 100. In other words, even when an external force is applied directly to the endothermic pouch 100 through the exposed surface of the rim frame 210, the projection 230 penetrates and supports the heat-fusion sealing portion 120, so that the endothermic pouch 100 does not detach from the rim frame 210 in response to an external force within the bursting strength of the heat-fusion sealing portion 120.
In addition, turning to
Thus, in the second embodiment, the pouch cartridge 200 can be manufactured in a one-step manner through hook joining without the use of heat-fusion or bonding to join the pair of rim frames 210. However, even when applying the hook structure, it is of course possible to use a combination of heat-fusion or bonding to provide a more robust bonding of the rim frames 210.
Furthermore, an incision 126 is formed on the heat-fusion sealing portion 120 of the endothermic pouch 100 at a location corresponding to the hooks 240 of the rim frame 210. The incisions 126 are to provide a space for the pair of hooks 240 to approach and engage each other, and the formation of the incisions 126 facilitates the engagement of the hooks 240.
The present invention has been described above in more detail through the drawings and embodiments. However, the configurations described in the drawings or the embodiments in the specification are merely embodiments of the present invention and do not represent all the technical ideas of the present invention. Thus, it is to be understood that there may be various equivalents and variations in place of them at the time of filing the present application.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2022-0071856 | Jun 2022 | KR | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/KR2023/007993 | 6/12/2023 | WO |
