Secondary battery module with improved temperature stability inside the module

Abstract

The present invention relates to a heat absorption pack for a secondary battery module and a secondary battery module including the same. The heat absorption pack includes a highly absorbent matrix impregnated with water inside a pouch, and a heat dispersion substrate is inserted between the highly absorbent matrix and the pouch. As a result, the heat absorption pack can absorb a large amount of heat in the vicinity when heat is generated inside the module, and when the heat absorption pack is provided in a secondary battery module, the surrounding temperature of the secondary battery can be prevented from changing suddenly. In addition, the highly absorbent matrix of the heat absorption pack is uniformly exposed to the surrounding thermal energy, and damage to the heat absorption pack due to heat generation inside the module can be prevented. Therefore, the heat absorption pack can perform more stable temperature control inside the module, thereby improving the performance and stability of the secondary battery according to the surrounding temperature.

Description

[Technical Field]

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0154484, dated November 17, 2022, and all contents disclosed in the documents of this Korean patent application are incorporated herein by reference.

[0002] The present invention relates to a heat-absorbing pack for a secondary battery module that can uniformly absorb thermal energy when the temperature inside the secondary battery module rises, thereby preventing large changes in the internal temperature, and a secondary battery module including the same that has improved stability against temperature changes inside the module. [Background technology]

[0003] BACKGROUND ART In recent years, secondary batteries have been widely used not only in small devices such as portable electronic devices but also in medium to large devices such as battery packs for hybrid cars and electric cars or power storage devices.

[0004] A secondary battery includes an electrode assembly including a positive electrode, a negative electrode, and a separator, an electrolyte, and a multilayer exterior material that protects them. Such a secondary battery can be used in the form of a battery module in which multiple cells are mounted.

[0005] However, such secondary batteries are sensitive to changes in ambient temperature, which can significantly affect their electrical performance and safety.

[0006] For example, an electrode assembly included in a secondary battery generates heat during charging and discharging. This heat not only reduces the performance of the secondary battery cell but also increases the temperature of the secondary battery cell itself, which can lead to cell explosion. The cell explosion can cause high temperatures and pressures in other surrounding secondary battery cells, leading to chain reactions that can lead to secondary battery cell explosions.

[0007] Conventional thermal runaway prevention sheet technologies have been developed to suppress heat transfer to adjacent cells during thermal runaway in secondary batteries. For example, a technology has been developed that improves heat transfer efficiency by installing a cartridge containing a thermally conductive additive inside a battery module. However, because this conventional technology is designed to cool the heat generated during battery operation, it has a problem of not functioning properly in thermal runaway situations such as cell explosion. Another example has been developed, which includes a cooling member that absorbs heat generated inside a secondary battery module to lower the ambient temperature. However, actual thermal runaway is often caused by heat generated by a specific cell installed in the module. In this case, the cooling member has difficulty uniformly absorbing the heat generated in the cells, which can lead to damage to the cooling member during the heat absorption process, resulting in limitations in the cooling member's ability to sufficiently absorb internal heat.

[0008] Therefore, in a secondary battery module including a secondary battery, when the temperature inside the module, i.e., the temperature around the secondary battery, is in a high temperature / heat generating condition that induces thermal runaway of the battery, there is a need to develop a technology that can effectively and uniformly absorb the ambient temperature and prevent the temperature inside the module from rising suddenly. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Korean Patent Publication No. 10-2015-0000725 Summary of the Invention [Problem to be solved by the invention]

[0010] Therefore, an object of the present invention is to provide a technology that can suppress abrupt temperature changes inside a secondary battery module by uniformly absorbing the heat generated when heat is generated inside the module. [Means for solving the problem]

[0011] To solve the above-mentioned problems, In one embodiment, the present invention comprises: a highly absorbent matrix; a heat dissipation substrate disposed on at least one surface of the highly absorbent matrix; a pouch into which the high-absorbency matrix having the heat-dispersing substrate disposed thereon is inserted; The highly absorbent matrix is ​​impregnated with water, The heat dissipating substrate provides a heat absorbing pack for a secondary battery module, which has a plurality of pinholes on one side edge.

[0012] In this case, the pouch may include a venting guide on one side edge, and the heat dissipation substrate may be inserted such that the pinhole is located on the same side as the venting guide.

[0013] The heat dissipating substrate may have an average thickness of 5 μm to 100 μm and may contain a metal having a thermal conductivity of 50 kcal / ° C. or more.

[0014] The superabsorbent matrix may also be in the form of a superabsorbent polymer (SAP) or a superabsorbent fiber (SAF).

[0015] The superabsorbent matrix may also comprise one or more of the following resins: polyacrylic acid, polyacrylates, polyacrylate graft polymers, starch, crosslinked carboxymethyl cellulose, acrylic acid copolymers, hydrolyzed starch-acrylonitrile graft copolymers, starch-acrylic acid graft copolymers, saponified vinyl acetate-acrylic acid ester copolymers, hydrolyzed acrylonitrile copolymers, hydrolyzed acrylamide copolymers, ethylene-maleic anhydride copolymers, isobutylene-maleic anhydride copolymers, polyvinyl sulfonic acid, polyvinyl phosphonic acid, polyvinyl phosphoric acid, polyvinyl sulfate, sulfonated polystyrene, polyvinylamine, polydialkylaminoalkyl(meth)acrylamide, polyethyleneimine, polyallylamine, polyallylguanidine, polydimethyldiallylammonium hydroxide, quaternized polystyrene derivatives, guanidine-modified polystyrene, quaternized poly(meth)acrylamide, and polyvinyl guanidine.

[0016] In addition, the superabsorbent matrix may optionally further contain a thermally conductive filler therein along with the resin.

[0017] Such highly absorbent matrices can contain between 10 g / g and 500 g / g of water.

[0018] Furthermore, in one embodiment, the present invention provides a housing member; a plurality of battery cells inserted into the housing member; and a heat-absorbing pack according to the present invention that absorbs heat generated in the plurality of battery cells.

[0019] Here, the plurality of battery cells may be aligned in n rows (where n≧2), and in this case, the heat absorption pack may be disposed between the rows of the arranged battery cells, and / or may be disposed in the space between the outer surface of the row of the arranged battery cells and the housing member.

[0020] The heat-absorbing pack may be inserted such that the surface of the heat-absorbing pack is perpendicular to the bottom surface of the secondary battery module, and the venting guide of the heat-absorbing pack may be positioned at the top. [Effects of the Invention]

[0021] The heat-absorbing pack for a secondary battery module according to the present invention has a structure in which a water-impregnated high-absorbency matrix is ​​contained within a pouch, and a heat-dispersing substrate with a pinhole is inserted between the high-absorbency matrix and the pouch. This allows the heat-absorbing pack to absorb a large amount of heat from the surrounding area when heat is generated within the module, thereby preventing a sudden change in the temperature around the secondary battery when the pack is installed in a secondary battery module.

[0022] In addition, the heat absorption pack includes a heat dissipation substrate with pinholes, which can filter water vapor when the heat absorption pack is vented and increase the latent heat of water vapor within the module, thereby providing the advantage of good heat absorption efficiency.

[0023] Furthermore, the heat dissipation substrate allows the highly absorbent matrix of the heat absorption pack to be uniformly exposed to the surrounding heat energy, which can prevent damage to the heat absorption pack due to heat generated inside the module. Therefore, the heat absorption pack can more stably control the temperature inside the module, thereby improving the performance and stability of the secondary battery according to the surrounding temperature. [Brief explanation of the drawings]

[0024] [Figure 1] 1 is a perspective view showing a structure of a secondary battery module according to the present invention; [Figure 2] 1 is a perspective view showing the structure of a heat absorption pack according to the present invention. [Figure 3] FIG. 2 is a perspective view showing the configuration of a heat dissipating substrate and a highly absorbent matrix incorporated in a heat absorption pack. [Figure 4] FIG. 2 is a perspective view showing the configuration of a heat dissipating substrate and a highly absorbent matrix incorporated in a heat absorption pack. [Figure 5] 1 is a graph showing the temperature change over time at different positions on the heating surface and rear surface of the endothermic packs of Example 1 and Comparative Example 2 when one surface of each pack is heated with a torch. [Figure 6] 1 is a graph showing the temperature change over time at different positions on the rear surface of the endothermic packs of Example 1 and Comparative Example 2 when one surface of each pack is heated with a torch. [Figure 7] 1 is an image of the inside of the endothermic pack of Example 1 that has been disassembled after being heated on one side with a torch. [Figure 8] 1 is an image of the inside of the heat absorption pack of Comparative Example 1 that was decomposed after one side was heated with a torch. [Figure 9] 1 is an image of the inside of the heat absorption pack of Comparative Example 2 that was decomposed after one side was heated with a torch. DETAILED DESCRIPTION OF THE INVENTION

[0025] Because the present invention is susceptible to various modifications and can have various embodiments, specific embodiments are described in detail in the detailed description.

[0026] However, this is not intended to limit the invention to any particular embodiment, but rather to be understood as including all modifications, equivalents, or alternatives falling within the spirit and scope of the invention.

[0027] In the present invention, the terms "comprise" and "have" are intended to specify the presence of features, numbers, steps, operations, components, parts or combinations thereof described in the specification, and may be understood as not precluding the presence or possibility of addition of one or more other features, numbers, steps, operations, components, parts or combinations thereof.

[0028] Furthermore, in the present invention, when a layer, film, region, plate, or other portion is described as being "on" another portion, this includes not only the case where it is "directly on" the other portion, but also the case where there is another portion in between. Conversely, when a layer, film, region, plate, or other portion is described as being "under" the other portion, this includes not only the case where it is "directly under" the other portion, but also the case where there is another portion in between. Furthermore, in this application, being "located on" can include not only the case where it is located on top, but also the case where it is located below.

[0029] The present invention will now be described in more detail.

[0030] <Heat absorption pack for secondary batteries> In one embodiment, the present invention comprises: a highly absorbent matrix; a heat dissipation substrate disposed on at least one surface of the highly absorbent matrix; and a pouch into which the highly absorbent matrix having the heat dissipating substrate disposed thereon is inserted.

[0031] The heat-absorbing packs 30, 30a, and 30b according to the present invention are components inserted into the secondary battery module 1 as shown in FIG. 1, and have a structure in which a highly absorbent matrix impregnated with water is inserted into a pouch.

[0032] The high-absorbency matrix is ​​impregnated with water, allowing it to absorb a large amount of thermal energy depending on the temperature conditions around the endothermic pack, i.e., the internal temperature conditions of the secondary battery module to which the endothermic pack is attached. Specifically, the water is impregnated within the high-absorbency matrix, and when the temperature outside the pouch rises, it vaporizes and separates from the high-absorbency matrix. The water requires a large amount of heat to vaporize, and absorbs the heat around the pouch to meet this requirement. This prevents a sudden rise in the internal temperature when heat is generated inside the module.

[0033] In the heat-absorbing pack 30 according to the present invention, a heat-dispersing substrate may be disposed on at least one surface of the highly absorbent matrix so that the water impregnated in the highly absorbent matrix can uniformly absorb heat. Specifically, the heat-dispersing substrate may be in the form of a sheet and disposed on each surface of the highly absorbent matrix so as to cover the surface, or may be in the form of a rectangular sheet and disposed so as to wrap around the highly absorbent matrix.

[0034] 2 and 3, the heat dissipating substrate 320 may have the form of a pouch or bag so as to surround the entire surface of the high-absorbency matrix 330. In this case, the heat dissipating substrate 320 may be inserted into the pouch 310, which is the outer casing of the heat absorption pack 30, with the high-absorbency matrix 330 housed inside. In this case, the heat dissipating substrate 320 not only has a filtering effect on water vapor evaporated when the heat absorption pack 30 is vented, but also increases the latent heat of the water vapor within the module, thereby providing the advantage of good heat absorption efficiency.

[0035] The heat dissipating substrate 320 may include a plurality of pinholes 325 on one side edge of the substrate. The pinholes 325 provide a path for water vapor to pass through when the external temperature of the endothermic pack 30 increases, and also function as a filter to prevent components other than water vapor, such as the highly absorbent matrix 330 components partially dissolved in water, from leaking out when the endothermic pack 30 is vented. The pinholes 325 function as a filter to prevent components other than water from escaping to the outside when the endothermic pack 30 is vented, thereby increasing the amount of latent heat generated by water vapor and further improving the heat absorption performance of the endothermic pack.

[0036] 4, a plurality of pinholes 325 may be provided in a line at predetermined intervals on one side edge of the heat dissipating substrate 320. Specifically, one or more lines of such pinholes 325 may be introduced, for example, 1 to 5 lines or 2 to 4 lines. By introducing the pinholes 325 into the heat dissipating substrate 320 in a plurality of lines as described above, the present invention can improve the discharge and filtering efficiency of water vapor during venting of the heat absorption pack 30.

[0037] For example, when the heat dissipation substrate 320 has a pouch shape, the pinholes 325 may be provided in the insertion portion 323 into which the superabsorbent matrix 330 is inserted, and may be provided adjacent to the sealing portion 324 that is joined at the edge of the heat dissipation substrate 320 to provide the interior. In this case, the pinholes 325 may be provided in a row on each side edge of the first substrate surface 321 and the second substrate surface 322 of the pouch-shaped heat dissipation substrate 320, and may be located on both sides of the sealing portion 324 after the heat dissipation substrate 320 is sealed.

[0038] 2, the pinhole 325 may be arranged to be located on the same side as the venting guide 313 of the pouch 310 in which the heat dissipation substrate 320 is housed. In this case, after the water impregnated in the highly water-absorbent matrix evaporates, a high venting pressure can be applied to the venting guide 313 provided on the pouch 310 when the endothermic pack 30 is vented, thereby further improving the endothermic performance of the endothermic pack 30.

[0039] The pinholes 325 may be formed by punching one side edge of the heat dissipating substrate. Punching may be performed using a method commonly used in the art. Specifically, the pinholes 325 may be formed by using a forming die for forming circular holes without forming any additional irregularities on the pinhole-forming surface. Alternatively, the pinholes 325 may be formed by piercing one side edge of the heat dissipating substrate 320 using a perforating means such as a heated needle to guide fluid flow from the inside to the outside of the heat dissipating substrate 320. As a result, the outer surface of the heat dissipating substrate 320 may protrude in the direction of the pinhole 325. In this case, the heat dissipating substrate 320 may be positioned such that the protruding portion of the pinhole 325 is located along a path along which water impregnated in the high-absorbency matrix 330 evaporates and moves to the venting guide 313 of the pouch 310.

[0040] In addition, the heat dissipation substrate 320 can uniformly transfer heat from outside the endothermic pack 30 to the highly absorbent matrix 330, thereby preventing the generated heat from concentrating on one part of the endothermic pack 30 and damaging the endothermic pack.

[0041] For this purpose, the heat dissipating substrate 320 may include a metal sheet with high thermal conductivity, and the metal sheet may include a metal having a thermal conductivity of 50 kcal / °C or more. More specifically, the metal sheet may include a metal having a thermal conductivity of 70 kcal / °C or more, 80 kcal / °C or more, 90 kcal / °C or more, 100 kcal / °C or more, 50 kcal / °C to 400 kcal / °C, 70 kcal / °C to 370 kcal / °C, 70 kcal / °C to 150 kcal / °C, 100 kcal / °C to 370 kcal / °C, 150 kcal / °C to 200 kcal / °C, or 250 kcal / °C to 350 kcal / °C.

[0042] As an example, the metal sheet may include aluminum having a thermal conductivity of 196±3 kcal / °C, tungsten having a thermal conductivity of 170±3 kcal / °C, copper having a thermal conductivity of 320±3 kcal / °C, nickel having a thermal conductivity of 77±3 kcal / °C, or the like, either alone or in combination.

[0043] Furthermore, the heat dissipating substrate 320 includes a metal sheet with high thermal conductivity, but the heat transferred to the highly absorbent matrix 330 through the metal sheet must be dispersed over the entire surface of the highly absorbent matrix 330, and therefore may be highly dependent on the thickness of the metal sheet. Therefore, the heat dissipating substrate 320 may have a predetermined thickness to transfer heat from the periphery of the pouch 310 (i.e., outside the pouch) to the highly absorbent matrix 330 with high efficiency and in a more uniformly dispersed manner, and may satisfy a certain thickness requirement with the heat absorption pack 30 when considering the reduction in energy density of the secondary battery module 1 due to the heat absorption pack 30 and the thermal conduction efficiency of the metal sheet itself included in the heat dissipating substrate.

[0044] For example, the heat dispersing substrate 320 may have an average thickness of 5 μm to 100 μm, and the thickness ratio of the heat dispersing substrate 320 to the average thickness of the heat absorption pack 30 may satisfy the following formula 1, which is 10 to 500:

[0045] [Formula 1] T pack / T sheet

[0046] In the above formula 1, T pack represents the average thickness of the endothermic pack (unit: μm), T sheet represents the average thickness of the metal sheet (unit: μm).

[0047] Specifically, the above formula 1 is the ratio between the average thickness of the heat absorption pack 30 and the average thickness of the heat dissipating substrate 320, and by ensuring that this ratio satisfies a predetermined range, it is possible to prevent a reduction in the energy density of the secondary battery module 1 and efficiently disperse and absorb thermal energy to the heat absorption pack 30 without damaging the heat absorption pack 30 when high temperatures are generated inside. For this reason, the heat dissipating substrate 320 of the present invention may satisfy the above formula 1 at a value of 10 to 500, specifically 10 to 400, 10 to 300, 10 to 200, 10 to 100, 10 to 50, 100 to 300, or 100 to 200. By satisfying Equation 1 with a value of 10 or more, the heat dissipating substrate can prevent a reduction in the content of superabsorbent matrix 330 and a decrease in heat absorption efficiency. On the other hand, by satisfying Equation 1 with a value of 500 or less, the thin thickness of heat dissipating substrate 320 can prevent the heat around pouch 310 from being uniformly dispersed to superabsorbent matrix 330, which could result in damage to endothermic pack 30.

[0048] The heat dissipating substrate 320 may have an average thickness of 5 μm to 100 μm, more specifically, 5 μm to 75 μm, 5 μm to 50 μm, 5 μm to 30 μm, 10 μm to 30 μm, or 15 μm to 25 μm.

[0049] By adjusting the average thickness of the heat dissipating substrate 320 to the above range, the present invention can prevent the endothermic pack 30 from being damaged during heat absorption due to a thickness of less than 5 μm, which would prevent the heat around the pouch 310 from being uniformly transferred to the highly absorbent matrix 330, while preventing the thermal conductivity of the heat dissipating substrate 320 from being reduced due to an excessive thickness of more than 100 μm.

[0050] In addition, in order to more uniformly absorb heat around the pouch 310, the high-absorbency matrix 330 may have the heat dissipation substrate 320 disposed on the surface that directly contacts the pouch 310 so as to have a predetermined area ratio.

[0051] Specifically, the heat dissipating substrate 320 may be disposed so as to cover 70% or more of the entire surface of the superabsorbent matrix 330, and more specifically, so as to cover 75% or more, 80% or more, 85% or more, or 90% or more of the entire surface of the superabsorbent matrix 330. In some cases, the heat dissipating substrate 320 may be disposed over the entire surface of the superabsorbent matrix 330, and the area where the superabsorbent matrix 330 is in direct contact with the pouch may be 0%. In the present invention, by adjusting the area ratio of the heat dissipating substrate 320 covering the surface of the superabsorbent matrix 330 within the above range, the heat around the pouch 310 may be more uniformly dispersed to the superabsorbent matrix 330.

[0052] Meanwhile, as described above, the superabsorbent matrix 330 may have a fibrous form such as cubes or nonwoven fabric before being soaked in water, and after soaking in water, it may have a form such as a slurry or suspension depending on the amount of water soaked in. When the endothermic pack 30 is exposed to high temperatures, the water soaked in the superabsorbent matrix 330 may evaporate and separate, and the pouch containing the superabsorbent matrix 330 may then have an expanded form.

[0053] The superabsorbent matrix 330 may include a superabsorbent polymer (SAP) or a superabsorbent fiber (SAF) to efficiently absorb water. The SAP and SAF may be differentiated by their shapes. For example, the SAP may be powder-shaped, while the SAF may be linear.

[0054] The superabsorbent resin (SAP) and the superabsorbent fiber (SAF) may be composed of the same or different components. Specifically, the superabsorbent matrix may be one or more selected from the group consisting of polyacrylic acid, polyacrylates, polyacrylate graft polymers, starch, crosslinked carboxymethyl cellulose, acrylic acid copolymers, hydrolyzed starch-acrylonitrile graft copolymers, starch-acrylic acid graft copolymers, saponified vinyl acetate-acrylic acid ester copolymers, hydrolyzed acrylonitrile copolymers, hydrolyzed acrylamide copolymers, ethylene-maleic anhydride copolymers, isobutylene-maleic anhydride copolymers, polyvinyl sulfonic acid, polyvinyl phosphonic acid, polyvinyl phosphoric acid, polyvinyl sulfate, sulfonated polystyrene, polyvinylamine, polydialkylaminoalkyl(meth)acrylamide, polyethyleneimine, polyallylamine, polyallylguanidine, polydimethyldiallylammonium hydroxide, quaternized polystyrene derivatives, guanidine-modified polystyrene, quaternized poly(meth)acrylamide, polyvinyl guanidine, and mixtures thereof.

[0055] As an example, the superabsorbent matrix 330 may be one or more selected from the group consisting of cross-linked polyacrylate, cross-linked polyacrylic acid, and cross-linked acrylic acid copolymer, but is not limited thereto.

[0056] In the present invention, the type of acrylic acid copolymer used as the superabsorbent matrix 330 is not particularly limited, but it is preferably a copolymer containing an acrylic acid monomer and one or more comonomers selected from the group consisting of maleic acid, itaconic acid, acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, 2-(meth)acryloylethanesulfonic acid, 2-hydroxyethyl (meth)acrylate, and styrenesulfonic acid.

[0057] The above component is a material having a network structure with hydrophilic functional groups and can absorb water with high efficiency, so that the heat absorption or heat generation effect of the heat absorption pack can be realized uniformly.

[0058] The high-absorbency matrix 330 may also have a water absorption capacity within a certain range. Specifically, the high-absorbency matrix may have a water absorption capacity of 10 g / g to 500 g / g, more specifically, 50 g / g to 200 g / g, but is not limited thereto. This means that 1 g of the high-absorbency matrix can absorb 10 g to 500 g of water, preferably 50 g to 200 g of water. The higher the water absorption capacity of the high-absorbency matrix 330, the longer the cooling effect can last. However, if the water absorption capacity exceeds 500 g / g, the fluidity of the high-absorbency matrix 330 increases, making it difficult to maintain its shape and resulting in ineffective cooling. Furthermore, if the water absorption capacity of the high-absorbency matrix 330 is less than 10 g / g, the amount of heat absorbed in response to the temperature outside the pouch will be significantly reduced, resulting in a low effect of suppressing sudden changes in the temperature inside the module and thus inefficient.

[0059] Additionally, the highly absorbent matrix 330 may further include a thermally conductive filler therein to better transfer heat to the water impregnated within the matrix.

[0060] The thermally conductive filler may be used without limitation as long as it has excellent heat transfer properties, and specifically, one or more fillers selected from the group consisting of inorganic oxide fillers, metal hydroxide fillers, inorganic carbide fillers, nitride fillers, metal fillers, and carbon fillers may be used.

[0061] Examples of the inorganic oxide filler include aluminum oxide, magnesium oxide, zinc oxide, and silicon oxide. Examples of the metal hydroxide filler include aluminum hydroxide and magnesium hydroxide. Examples of the inorganic carbide filler include silicon carbide. Examples of the nitride filler include aluminum nitride, boron nitride, and silicon nitride. Examples of the metal filler include silver, copper, zinc, iron, aluminum, nickel, tin, and alloys thereof. Examples of the carbon filler include carbon and graphite.

[0062] Furthermore, the shape of the thermally conductive filler is not particularly limited, but it may have a spherical shape with a high specific surface area to effectively transfer heat inside the highly absorbent matrix, or it may have a needle-like or fibrous shape to form a thermal network with adjacent thermally conductive fillers.

[0063] Furthermore, the pouch 310 may be applied without any particular limitation as long as it can effectively transfer external heat to the superabsorbent matrix 330 inserted therein. For example, the pouch 310 may be made of a metal layer, an inner resin layer containing a cross-linked polyolefin resin may be provided on the inner surface of the metal layer, and an outer resin layer for protecting the heat-absorbing pack 30 may be provided on the outer surface of the metal layer.

[0064] The metal layer may include an aluminum layer that can effectively transfer heat from the outside of the heat absorption pack 30 to the inside, has a certain level of strength, and is resistant to external forces.

[0065] The inner resin layer is located on the inner surface of the metal layer and may function to prevent the water impregnated in the superabsorbent matrix 330 from reacting with the metal layer of the pouch. To this end, the inner resin layer may include a crosslinked polyolefin-based resin. Crosslinked polyolefin-based resins have low hygroscopicity and can inhibit the penetration of water impregnated in the superabsorbent matrix, thereby preventing the inner resin layer from swelling or erosion. The polyolefin-based resin may have a crosslinking degree of 10 to 70%, specifically 30 to 50%. The polyolefin-based resin may be at least one selected from the group consisting of polypropylene (PP) and polyethylene (PE). The crosslinked polyolefin-based resin may specifically include crosslinked polyethylene, crosslinked polypropylene, or a mixture thereof, more specifically crosslinked polypropylene.

[0066] Furthermore, since the outer resin layer must have excellent resistance to the external environment to protect the endothermic pack 30 from the outside, it is required to have excellent tensile strength and weather resistance relative to its thickness, and may be made of, for example, polyester-based resins such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), etc., polyolefin-based resins such as polyethylene (PE) and polypropylene (PP), polystyrene-based resins such as polystyrene, polyvinyl chloride-based resins, polyvinylidene chloride-based resins, etc. These materials may be used alone or in combination, and ONy (oriented nylon film) may also be used.

[0067] In addition, when water impregnated in the superabsorbent matrix 330 evaporates due to external heat, a difference in gas pressure occurs between the inside and outside of the pouch, and the pouch 310 includes a venting induction part 313 that discharges the vaporized water vapor due to the difference in pressure to the outside. To this end, the venting induction part 313 may be provided on one side edge of the pouch 310 to facilitate the discharge of the water vapor, and more specifically, may be provided adjacent to the pouch sealing part 314.

[0068] In addition, when there is no or little difference in pressure between the inside and outside of the endothermic pack 30, the venting induction unit 313 does not discharge gas (i.e., discharge water vapor) and is in a state of blocking the inflow of external substances into the endothermic pack 30. However, when the pressure difference between the inside and outside of the endothermic pack 30 becomes 0.1 atm or more, water vapor is discharged through the venting induction unit 313 due to the air pressure difference. After that, when the pressure difference between the inside and outside of the endothermic pack 30 becomes 0.1 atm or less or disappears due to a certain amount of discharge, the process of blocking water vapor discharge again can be performed reversibly.

[0069] The venting guide 313 may have a laminated structure of a first layer having pores and a second layer without pores, and the first and second layers may be made of the same material containing polytetrafluoroethylene (PTFE). Polytetrafluoroethylene (PTFE) has excellent heat resistance and hydrophobic properties, making it an ideal material for the venting guide.

[0070] In addition, the first layer may have a structure in which pores are formed, while the second layer may have a structure in which pores are not formed, in the venting guide 313. Specifically, the first layer may have a structure in which open pores are formed, connecting the inside and outside, and the second layer may have a shape in which flexures are formed on the surface but no pores are formed. In the case of the second layer, since it is made of a PTFE material, gas can be discharged through minute gaps formed between the polymers.

[0071] Furthermore, the outer resin layer, metal layer, and inner resin layer of the pouch 310 have a perforated portion where the venting induction portion 313 is to be disposed. By disposing the venting induction portion 313 in this portion and then applying high-temperature pressure to the edge of the venting induction portion, the venting induction portion 313 can be stably attached to the inner surface of the pouch 310. More specifically, by disposing the venting induction portion 313 in the perforated portion of the pouch 310 and applying high-temperature pressure to the edge of the venting induction portion 313, the inner resin layer of the pouch 310 melts into the pores of the first layer of the venting induction portion, thereby stably attaching the venting induction portion 313 to the inner surface of the pouch. As a result, gas (e.g., water vapor) formed inside the pouch 310 can pass through the first and second layers of the venting induction portion 313 and be discharged to the outside. For this reason, the perforated portion of the pouch 310 may have an area smaller than the area of ​​the venting induction portion 313.

[0072] Meanwhile, polytetrafluoroethylene (PTFE) has a melting point of 327°C, which is significantly different from the melting point of approximately 160°C of polypropylene (PP), which is the main resin layer used in pouches. Therefore, when applying heat and pressure to attach the venting guide 313 made of polytetrafluoroethylene (PTFE) to the polypropylene (PP) inner resin layer, if the heating temperature is high enough to melt the polytetrafluoroethylene (PTFE), the polypropylene (PP) may be damaged. On the other hand, if the heating temperature is high enough to melt the polypropylene (PP) but not to damage it, the polytetrafluoroethylene (PTFE) does not melt, making it difficult for the two to bond to each other.

[0073] Therefore, in the present invention, a structure is used in which the venting induction part 313 is attached to the pouch so that the first layer having pores contacts the internal resin layer of the pouch. When the overlapping part of the pouch 310 and the venting induction part 313 is heated and pressurized to a high temperature to attach the venting induction part 313 to the pouch, a part of the internal resin layer hardens while melting into the pores of the first layer, and the internal resin layer is anchored to the first layer.

[0074] Furthermore, the endothermic pack 30 may satisfy a certain thickness requirement to effectively control the change in the internal temperature of the module 1. Specifically, the endothermic pack 30 may have a thickness of 0.1 mm to 50 mm, more specifically, 0.1 mm to 30 mm, 0.1 mm to 15 mm, 0.1 mm to 10 mm, 1 mm to 20 mm, 5 mm to 10 mm, 10 mm to 20 mm, or 1 mm to 5 mm.

[0075] In the present invention, by adjusting the thickness of the endothermic pack 30 to the above range, if the thickness is less than 0.1 mm, the thickness of the endothermic pack 30 is too thin, which may result in insufficient flow of thermal energy around the endothermic pack, resulting in a sudden change in the temperature inside the module, and if the thickness exceeds 50 mm, the thickness of the battery module increases, which may significantly reduce the energy density.

[0076] The heat absorption pack 30 according to the present invention, having the above-described configuration, can not only absorb a large amount of heat from the surrounding area when heat is generated inside the module, but also uniformly supply the heat to the high-absorbency matrix 330, thereby preventing damage to the heat absorption pack 30 due to heat generated inside the module. Therefore, when the heat absorption pack 30 is installed in a secondary battery module, it can prevent abrupt changes in the ambient temperature of the secondary battery, thereby improving the performance and stability of the secondary battery according to the ambient temperature.

[0077] <Secondary battery module> Furthermore, in one embodiment, the present invention provides A secondary battery module is provided, which includes a secondary battery and the above-described heat-absorbing pack for a secondary battery according to the present invention.

[0078] FIG. 1 is a perspective view showing the structure of a secondary battery module 1 according to the present invention, which will be described in more detail with reference to FIG.

[0079] A secondary battery module 1 according to the present invention includes a housing member 10, a plurality of battery cells 20 inserted into the housing member, and a heat absorption pack 30 that absorbs heat generated by the plurality of battery cells.

[0080] The secondary battery module 1 according to the present invention includes a plurality of battery cells 20 and is equipped with the heat absorption pack 30 according to the present invention described above, which can prevent the temperature inside the module from rising suddenly, and therefore has the advantage of excellent stability against the temperature of the battery cells 20.

[0081] Here, the housing member 10 serves as a body of the battery module that accommodates the plurality of secondary battery cells 20. The housing member 10 is a member that accommodates the plurality of battery cells 20, and protects the battery cells 20 while transmitting electrical energy generated by the battery cells 20 to the outside.

[0082] For this purpose, the housing member 10 may be composed of a bottom member 11 and side wall members 12. The bottom member 11 seats the plurality of battery cells 20 and supports the seated plurality of battery cells 20. In addition, a heat sink 40 may be disposed between the bottom member 11 and the battery cells 20, and the heat sink 40 may be configured to transfer heat generated in the battery cells 20 to the bottom member 11, and the bottom member 11 may be configured to transfer the heat transferred from the heat sink 40 to the outside for cooling.

[0083] Furthermore, the side wall member 12 forms the side of the housing member 10 and can also discharge heat generated in the battery cells 20 to the outside.

[0084] The housing member 10 may further include a cover member 13 provided on the upper end of the side wall member 12 to protect the upper end of the battery cell 20. In addition, a gas venting member 17 may be provided between the cover member 13 and the upper end of the battery cell 20 to discharge gas generated in the battery cell 20 to the outside during charging and discharging.

[0085] The housing member 10 may also include a front member 14 and a rear member 15 adjacent to the side wall member 12, and may thereby be configured in a form that surrounds the sides of the plurality of battery cells 20.

[0086] Furthermore, the housing member 10 may include additional components such as bus bar members (not shown) that electrically connect the battery cells 20 to the outside.

[0087] Meanwhile, the type of the battery cell 20 is not particularly limited as long as it has a shape that can be applied as a lithium secondary battery, and specifically, the battery cell 20 may have a shape such as a prismatic shape, a pouch shape, a cylindrical shape, etc. As one example, the battery cell 20 may be a prismatic or pouch-shaped lithium secondary battery.

[0088] The battery cells 20 may be inserted into the housing member 10 and aligned in n rows (where n≧2) so as to face the sidewall members 12 of the housing member 10. Specifically, the battery cells 20 may be aligned in two or more rows, three or more rows, or two to four rows so as to face the sidewall members 12.

[0089] The heat absorption packs 30 may be disposed adjacent to the aligned battery cells 20. As one example, the heat absorption packs 30a may be disposed on the outer surfaces of the aligned battery cells 20, i.e., in the spaces between the housing member 10 and the battery cells 20.

[0090] As another example, heat absorption packs 30b may be inserted between the battery cells 20. Specifically, the heat absorption packs 30b may be disposed between the individual battery cells 20 constituting one row, and in some cases, may be disposed between the first row 21a and the second row 21b composed of the batteries arranged as shown in FIG.

[0091] In this way, by arranging the heat absorption pack 30 adjacent to the battery cell 20, if heat is generated in the battery cell 20, the heat can be absorbed immediately, thereby preventing sudden temperature changes inside the module.

[0092] In addition, the endothermic pack 30 may be arranged so that the venting guide is exposed to the top of the module so that water vapor vaporized inside when exposed to high temperatures can be easily vented. Specifically, the endothermic pack 30 may be inserted into the module so that its surface is perpendicular to the bottom surface of the module, i.e., the bottom member 11. In this case, the venting guide provided on one side edge of the endothermic pack may be arranged adjacent to the top of the module, for example, the cover member 13 and / or the gas venting member 17 of the module.

[0093] The present invention will be described in more detail below with reference to examples and experimental examples.

[0094] However, the following examples and experimental examples are merely illustrative of the present invention, and the content of the present invention is not limited to the following examples and experimental examples.

[0095] Example 1: Manufacture of endothermic pack

[0096] A rectangular aluminum (Al) sheet was prepared as a heat dissipation substrate. The aluminum sheet was folded in half along its longitudinal axis, and the two adjacent sides of the folded aluminum sheet were sealed. Next, two pinhole lines were formed along the edge of the remaining unsealed side, with 10 pinholes in each line. A superabsorbent fiber was then inserted inside the sealed aluminum (Al) sheet, and water was injected to impregnate the superabsorbent fiber. The water was impregnated at a rate of 10 g per 1 g of superabsorbent fiber (component: acrylic acid copolymer). A vacuum was then created inside the aluminum (Al) sheet, and the open side was sealed so that the pinholes were positioned inside the sealed area (e.g., the unsealed area), producing an aluminum bag containing water-impregnated superabsorbent fiber inside the aluminum sheet.

[0097] Separately, an aluminum pouch measuring 9 cm wide and 12 cm long was prepared, which included an aluminum layer, a polypropylene (PP) layer on the outside of the aluminum layer, and a polyethylene (PE) layer with a cross-linking degree of 40±2% on the inside of the aluminum layer. The aluminum bag prepared earlier was inserted into the prepared aluminum pouch, and the inside of the pouch was evacuated. The pouch's opening was then sealed to prepare an endothermic pack.

[0098] In this case, the pouch has a venting guide portion on one side edge, and the venting guide portion has a two-layer structure made of polytetrafluoroethylene (PTFE), and the first layer has an open structure in which pores are formed to connect the inside and outside, and the second layer has a structure in which pores are not formed, and the second layer has a structure in which the second layer is arranged to face the inside of the pouch.

[0099] In addition, when inserting an aluminum bag into the pouch, the pinhole of the aluminum bag and the venting guide of the pouch were positioned adjacent to each other on the same side.

[0100] Example 2: Manufacture of endothermic pack

[0101] A pouch identical to that used in Example 1 was prepared. Separately, two aluminum (Al) sheets measuring 8.5 cm wide and 11.5 cm long were prepared as heat-dissipating substrates and inserted into the prepared pouch. Next, a superabsorbent fiber was inserted between the two inserted aluminum (Al) sheets, and water was injected to impregnate the superabsorbent fiber. At this time, 10 g of water was impregnated per 1 g of superabsorbent fiber (component: acrylic acid copolymer). The inside of the pouch was then evacuated, and the pouch's opening was sealed to produce a heat-absorbing pack.

[0102] At this time, two pinhole lines were formed on one side edge of the aluminum (Al) sheet, each line consisting of 10 pinholes, and the pinhole lines were arranged adjacent to each other by being located on the same side as the venting guide portion of the pouch.

[0103] <Comparative Example 1. Manufacture of Endothermic Pack>

[0104] The heat-absorbing pack was manufactured in the same manner as in Example 1, except that the rectangular aluminum (Al) sheet serving as the heat-dissipating substrate was not used and the heat-absorbing fiber was directly inserted into the pouch.

[0105] <Comparative Example 2. Production of Endothermic Pack>

[0106] The heat-dissipating pack was manufactured in the same manner as in Example 1, except that the aluminum bag (Al bag) made using a rectangular aluminum (Al) sheet as the heat-dissipating substrate had no pinholes.

[0107] <Experimental Example>

[0108] The heat absorbing effect of the heat absorbing pack according to the present invention was evaluated.

[0109] Specifically, each endothermic pack manufactured in the examples and comparative examples was fixed vertically, and three temperature sensors were attached to each side of the fixed endothermic pack, with the three temperature sensors attached to each side being located at the top, center, and bottom of the surface of the vertically fixed endothermic pack.

[0110] Next, the center of one side of the endothermic pack was heated for 10 minutes using a torch using butane gas as the raw material, and the temperatures of the surface heated by the torch (i.e., the heated surface) and the rear surface were measured during heating.

[0111] After the heating using the torch was completed, the endothermic pack was cooled, disassembled, and the presence or absence of damage to the highly absorbent fiber inserted in the pouch inside the endothermic pack was visually evaluated.

[0112] The results are shown in Table 1 below and in Figures 5 to 9, and the presence or absence of damage to the superabsorbent fiber is indicated by ◯ if there was damage, and × if there was no damage.

[0113] [Table 1]

[0114] As shown in Table 1 above and FIGS. 5 to 9, it can be seen that the heat-absorbing packs of the examples according to the present invention stably suppress a sudden temperature rise inside the battery module.

[0115] Specifically, looking at Table 1 and Figures 5 and 6, it was confirmed that the center of the endothermic pack of the example, which is directly heated by the torch, has the highest temperature in the case of the heated surface, followed by the top and bottom, while the rear surface has the highest temperature in the order of top > center > bottom. This means that the water contained inside the endothermic pack absorbs the energy required to vaporize and separate from the highly absorbent fiber, thereby reducing the heat transferred to the rear surface of the endothermic pack.

[0116] It was also confirmed that the temperatures of the heating surface and rear surface of the heat absorption packs of the Examples were generally lower than those of the heat absorption packs of the Comparative Examples. This means that when a heat dispersion substrate is introduced into the pouch, it is possible to more effectively disperse external heat to the highly absorbent fibers, and when pinholes are introduced into such a heat dispersion substrate, it is possible to selectively release evaporated water vapor to the outside, thereby further increasing the latent heat of water.

[0117] Furthermore, as shown in Figure 7, it was confirmed that in the endothermic pack of the Example, the superabsorbent fiber inserted inside the pouch uniformly absorbed the heat around the pouch, and no internal damage to the superabsorbent fiber occurred. In contrast, referring to Figures 8 and 9, the endothermic pack of Comparative Example 1 did not have a heat dissipation substrate, i.e., an aluminum (Al) sheet, between the pouch and the superabsorbent fiber, or did not meet the thickness requirements of the present invention, and not only was it unable to sufficiently absorb the thermal energy inside the module, but internal damage occurred to both the superabsorbent fiber and the pouch when absorbing heat, indicating that the endothermic pack did not absorb heat stably.

[0118] From these results, it can be seen that the endothermic pack according to the present invention can absorb a large amount of heat inside the module under high temperature conditions, prevent the temperature inside the module from changing suddenly, and absorb the heat evenly inside the endothermic pack, preventing damage to the endothermic pack during the heat absorption process, thereby enabling more stable control of the temperature inside the module.

[0119] Although the present invention has been described above with reference to preferred embodiments, it will be understood that a person skilled in the art or having ordinary knowledge in the art can make various modifications and changes to the present invention without departing from the spirit and technical scope of the present invention as set forth in the claims below.

[0120] Therefore, the technical scope of the present invention is not limited to the content described in the Summary of the Invention of the specification, but can be defined by the claims. [Explanation of symbols]

[0121] 1: Secondary battery module 10: Housing material 11:Bottom member 12: Side wall member 13: Cover material 14: Front member 15: Rear member 16: Partition wall material 17: Gas venting components 20: Battery cell 21: A row of aligned battery cells 21a: First row of aligned battery cells 21b: Second row of aligned battery cells 30: Heat absorption pack 30a: Heat-absorbing pack placed on the outer surface of the battery cell 30b: Heat-absorbing packs arranged between multiple rows of aligned battery cells 40: Heat sink

Claims

1. a highly absorbent matrix; a heat dissipation substrate disposed on at least one surface of the highly absorbent matrix; a pouch into which the high-absorbency matrix having the heat-dispersing substrate disposed thereon is inserted; the highly absorbent matrix is ​​impregnated with water; The heat dissipating substrate has a plurality of pinholes on one side edge thereof.

2. The pouch includes a venting guide portion on one side edge, The heat-absorbing pack for a secondary battery module according to claim 1 , wherein the heat-dissipating substrate is inserted such that the pinhole is located on the same side as the venting guide.

3. 2. The heat-absorbing pack for a secondary battery module according to claim 1, wherein the heat-dissipating substrate has an average thickness of 5 μm to 100 μm.

4. 2. The heat-absorbing pack for a secondary battery module according to claim 1, wherein the heat-dissipating substrate contains a metal having a thermal conductivity of 50 kcal / [deg.] C. or more.

5. 2. The heat-absorbing pack for a secondary battery module according to claim 1, wherein the highly absorbent matrix is ​​a highly absorbent polymer (SAP) or a highly absorbent fiber (SAF).

6. 2. The heat-absorbing pack for a secondary battery module according to claim 1, wherein the superabsorbent matrix comprises one or more of polyacrylic acid, polyacrylates, polyacrylate graft polymers, starch, crosslinked carboxymethyl cellulose, acrylic acid copolymers, hydrolyzed starch-acrylonitrile graft copolymers, starch-acrylic acid graft copolymers, saponified vinyl acetate-acrylic acid ester copolymers, hydrolyzed acrylonitrile copolymers, hydrolyzed acrylamide copolymers, ethylene-maleic anhydride copolymers, isobutylene-maleic anhydride copolymers, polyvinyl sulfonic acid, polyvinyl phosphonic acid, polyvinyl phosphoric acid, polyvinyl sulfate, sulfonated polystyrene, polyvinylamine, polydialkylaminoalkyl(meth)acrylamide, polyethyleneimine, polyallylamine, polyallylguanidine, polydimethyldiallylammonium hydroxide, quaternized polystyrene derivatives, guanidine-modified polystyrene, quaternized poly(meth)acrylamide, and polyvinyl guanidine.

7. The heat-absorbing pack for a secondary battery module according to claim 1 , wherein the highly absorbent matrix further comprises a thermally conductive filler therein.

8. 2. The heat-absorbing pack for a secondary battery module according to claim 1, wherein the highly absorbent matrix contains 10 g / g to 500 g / g of water.

9. a housing member; a plurality of battery cells inserted into the housing member; and the heat absorption pack according to claim 1 that absorbs heat generated in the plurality of battery cells.

10. 10. The secondary battery module according to claim 9, wherein the plurality of battery cells are aligned in n rows (n≧2), and heat absorption packs are disposed between the rows of the arranged battery cells.

11. 10. The secondary battery module according to claim 9, wherein the plurality of battery cells are aligned in n rows (n≧2), and a heat absorption pack is disposed in a space between an outer surface of the row of arranged battery cells and the housing member.

12. 10. The secondary battery module of claim 9, wherein the endothermic pack is inserted such that a surface of the endothermic pack is perpendicular to a bottom surface of the secondary battery module and a venting guide portion of the endothermic pack is positioned at an upper portion.

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