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 that Korean patent application are incorporated herein by reference.

[0002] The present invention relates to a heat absorption 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 and having improved stability against temperature changes inside the module. [Background technology]

[0003] 2. Description of the Related 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-sized devices such as battery packs for hybrid and electric vehicles and power storage devices.

[0004] The secondary battery includes an electrode assembly including a positive electrode, a negative electrode, and a separator, an electrolyte, and a multi-layered exterior material that protects them as a main body. Such a secondary battery may be used in the form of a battery module in which a plurality of cells are mounted.

[0005] However, such secondary batteries are sensitive to changes in the surrounding temperature, and their electrical performance and safety can be significantly affected.

[0006] For example, an electrode assembly included in a secondary battery generates heat during charging and discharging. Such heat not only reduces the performance of the secondary battery cell, but also increases the temperature of the secondary battery cell itself, which may lead to the explosion of the cell. The explosion of a cell may provide high temperatures and pressure to other surrounding secondary battery cells, causing problems such as a chain reaction of explosions of secondary battery cells.

[0007] In order to suppress the heat conduction to adjacent cells in the thermal runaway state of the secondary battery, conventional thermal runaway prevention sheet technologies have been developed. For example, a technology has been developed that improves the heat transfer efficiency by providing a cartridge containing a thermally conductive additive in a battery module. However, since such conventional technology is intended to cool the heat generated during battery operation, there is a problem that it does not function in the thermal runaway state such as cell explosion. As another example, a technology including a cooling member that absorbs the heat generated inside the secondary battery module and lowers the surrounding temperature has been developed. However, actual thermal runaway often occurs due to the heat generated by a specific cell mounted in the module. In this case, the cooling member has difficulty in uniformly absorbing the heat generated in the cell, and thus the cooling member is damaged during the heat absorption process, which has the limitation of not being able to sufficiently absorb the 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 surrounding temperature and prevent the temperature inside the module from rising rapidly. [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 technique capable of suppressing 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 dispersing substrate disposed on at least one surface of the highly absorbent matrix; a pouch into which the highly absorbent matrix having the heat dispersing substrate disposed thereon is inserted; The highly absorbent matrix is ​​in a state of being immersed in water, The heat dissipating substrate provides a heat absorbing pack for a secondary battery module, the heat dissipating substrate having a plurality of pinholes on one side edge.

[0012] In this case, the pouch may include a venting inducing portion at one side edge, and the heat dispersion substrate may be inserted such that the pinhole is disposed on the same side as the venting inducing portion.

[0013] The heat dissipation 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] Additionally, the highly absorbent matrix may optionally further contain a thermally conductive filler therein along with the resin.

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

[0018] Further, in one embodiment, the present invention provides A housing member; A plurality of battery cells inserted into the housing member; and a heat absorption 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 is greater than or equal to 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] In addition, the heat absorbing pack may be inserted such that a surface of the heat absorbing pack is vertical with respect to a bottom surface of the secondary battery module, and the venting induction portion of the heat absorbing pack may be positioned at an upper portion. Effect 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 highly absorbent matrix is ​​included in a pouch, and a heat-dispersing substrate with a pinhole is inserted between the highly absorbent matrix and the pouch, so that the heat-absorbing pack can absorb a large amount of heat in the vicinity when heat is generated inside the module, and when the heat-absorbing pack is provided in a secondary battery module, it can prevent a sudden change in the temperature around the secondary battery.

[0022] In addition, the heat absorption pack includes a heat dissipation substrate having pinholes, which can realize a filtering effect on water vapor when the heat absorption pack is vented, and can increase the latent heat of water vapor in the module, thereby providing the advantage of good heat absorption efficiency.

[0023] Furthermore, the heat dissipation substrate allows the highly water-absorbent matrix to be uniformly exposed to the surrounding thermal energy, which can prevent damage to the heat absorption pack caused by heat generation inside the module, and 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 description of the drawings]

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

[0025] Since the present invention can be modified in various ways 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 it should be understood to include all modifications, equivalents, or alternatives falling within the spirit and scope of the invention.

[0027] In the present invention, terms such as "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 additional possibility of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

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

[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 dispersing 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 that are 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] At this time, the highly absorbent matrix is ​​impregnated with water, and thus can absorb a large amount of thermal energy according to the temperature conditions around the heat absorption pack, i.e., the internal temperature conditions of the secondary battery module to which the heat absorption pack is attached. Specifically, the water is impregnated inside the highly absorbent matrix, and when the external temperature of the pouch rises, it vaporizes and is separated from the highly absorbent matrix. At this time, the water requires a large amount of heat to vaporize, and in order to meet this requirement, the water absorbs the heat around the pouch, thereby preventing a sudden rise in the internal temperature when heat is generated inside the module.

[0033] Here, in the heat absorption 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 the highly absorbent matrix.

[0034] As an example, the heat dispersing substrate 320 may have the form of a pouch or bag so as to surround the entire surface of the highly absorbent matrix 330 as shown in Figures 2 and 3. In this case, the heat dispersing substrate 320 may be inserted into the pouch 310, which is the outer casing of the heat absorbing pack 30, with the highly absorbent matrix 330 stored therein. In this case, the heat dispersing substrate 320 not only has a filtering effect on the vaporized water vapor when the heat absorbing pack 30 is vented, but also has the advantage of being highly efficient at absorbing heat since it can increase the latent heat of the vapor in the module.

[0035] The heat dispersion substrate 320 may include a plurality of pinholes 325 on one side edge of the substrate. The pinholes 325 provide a path through which vaporized water passes when the external temperature of the endothermic pack 30 rises, and also function as a filter to prevent components other than water vapor, such as the highly water-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 being released out when the endothermic pack 30 is vented, thereby increasing the amount of latent heat due to water vapor, and thus further improving the heat absorbing performance of the endothermic pack.

[0036] At this time, the pinholes 325 may be provided in a line at a predetermined interval on one side edge of the heat dispersing substrate 320 as shown in Fig. 4. Specifically, the number of lines of the pinholes 325 may be one or more, for example, 1 to 5 lines or 2 to 4 lines. By introducing the pinholes 325 in the heat dispersing substrate 320 in a plurality of lines as described above, the present invention can increase the discharge of water vapor and the filter efficiency during ventilation of the heat absorption pack 30.

[0037] As an example, when the heat dispersing substrate 320 has a pouch shape, the pinholes 325 may be provided in the insertion portion 323 into which the highly absorbent matrix 330 is inserted, and may be provided adjacent to the sealing portion 324 that is joined to the edge of the heat dispersing 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 dispersing substrate 320, and may be located on both sides of the sealing portion 324 after the heat dispersing substrate 320 is sealed.

[0038] 2, the pinhole 325 may be disposed on the same side as the venting induction portion 313 of the pouch 310 in which the heat dispersion substrate 320 is housed. In this case, after the water impregnated in the highly water-absorbent matrix is ​​evaporated, a high venting pressure may be applied to the venting induction portion 313 provided in the pouch 310 during venting of the endothermic pack 30, so that the endothermic performance of the endothermic pack 30 may be further improved.

[0039] Also, the pinhole 325 may be formed by punching one side edge of the heat dispersing substrate. The punching may be applied in a manner commonly applied in the art. Specifically, the pinhole 325 may be formed by punching a circular hole using a molding die without forming a separate unevenness on the pinhole forming surface. Also, in some cases, the pinhole 325 may be formed by piercing one side edge of the heat dispersing substrate 320 using a piercing means such as a heated needle to induce a fluid flow from the inside to the outside of the heat dispersing substrate 320. As a result, the periphery of the pinhole 325 may have a shape in which the outer surface of the heat dispersing substrate 320 partially protrudes in the penetrating direction. Also, in this case, the heat dispersing substrate 320 may be arranged such that the protruding portion of the pinhole 325 is located along a path along which water impregnated in the highly absorbent matrix 330 vaporizes and moves to the venting induction portion 313 of the pouch 310.

[0040] In addition, the heat dispersion substrate 320 can uniformly transfer heat 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 having 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, etc., either alone or in combination.

[0043] In addition, the heat dissipating substrate 320 includes a metal sheet having high thermal conductivity, but the heat transferred to the highly absorbent matrix 330 through the actual metal sheet must be distributed 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 the heat around the pouch 310 (i.e., outside the pouch) to the highly absorbent matrix 330 with high efficiency and to distribute and transfer the heat more uniformly, and may satisfy a certain thickness condition with the heat absorption pack 30 when considering the reduction in the 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 may satisfy the following formula 1, which indicates a thickness ratio with respect to the average thickness of the heat absorbing pack 30 including the heat dispersing substrate 320, in a range of 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 of the average thickness of the heat absorption pack 30 to the average thickness of the heat dispersing substrate 320, and by making the ratio satisfy a predetermined range, it is possible to prevent a reduction in the energy density of the secondary battery module 1, and to 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 dispersing substrate 320 of the present invention may satisfy the above formula 1 at 10 to 500, specifically at 10 to 400, 10 to 300, 10 to 200, 10 to 100, 10 to 50, 100 to 300, or 100 to 200. By satisfying formula 1 with 10 or more, the heat dissipating substrate can prevent the content of highly absorbent matrix 330 from being reduced, thereby preventing a reduction in heat absorption efficiency. Meanwhile, by satisfying formula 1 with 500 or less, the thin thickness of heat dissipating substrate 320 can prevent the heat around pouch 310 from being uniformly dispersed in highly absorbent matrix 330, which would result in damage to heat absorption pack 30.

[0048] Moreover, the heat dispersing substrate 320 may have an average thickness of 5 μm to 100 μm, and more specifically, may have an average thickness of 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 dispersing substrate 320 to the above range, the present invention can prevent the heat absorbing pack 30 from being damaged during heat absorption due to a thin thickness of less than 5 μm that does not uniformly transfer heat around the pouch 310 to the highly absorbent matrix 330, while preventing a reduction in the thermal conductivity of the heat dispersing substrate 320 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 highly absorbent matrix 330 may have a heat dispersing substrate 320 disposed on the surface that is in direct contact with the pouch 310 so as to satisfy a predetermined area ratio.

[0051] Specifically, the heat dispersing substrate 320 may be arranged to cover 70% or more of the entire surface of the superabsorbent matrix 330, and more specifically, may be arranged 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 dispersing substrate 320 may be arranged on 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, the area ratio of the heat dispersing substrate 320 covering the surface of the superabsorbent matrix 330 may be adjusted to the above range, so that the heat around the pouch 310 may be more uniformly distributed to the superabsorbent matrix 330.

[0052] Meanwhile, as described above, the superabsorbent matrix 330 may have a fiber form such as a cube or a nonwoven fabric before being soaked in water, and may have a form such as a slurry or a suspension depending on the amount of water soaked in. When the heat-absorbing pack 30 is exposed to high temperature conditions, the superabsorbent matrix 330 soaked in water may have a form in which the water soaked therein is vaporized and separated, and thus the pouch into which the superabsorbent matrix 330 is inserted may have an expanded form.

[0053] Here, the super absorbent matrix 330 may include a super absorbent polymer (SAP) or a super absorbent fiber (SAF) to absorb water efficiently. Here, the super absorbent polymer (SAP) and the super absorbent fiber (SAF) may be classified according to their shapes. For example, the super absorbent polymer (SAP) may have a powder shape, and the super absorbent fiber (SAF) may have a linear shape.

[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 sulfuric acid, 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 highly absorbent matrix 330 may be one or more selected from the group consisting of cross-linked polyacrylates, cross-linked polyacrylic acids, and cross-linked acrylic acid copolymers, 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 may be 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 components are materials having a network structure with hydrophilic functional groups and can absorb water with high efficiency, so that the heat absorbing pack can uniformly absorb or generate heat.

[0058] In addition, the high-absorbency matrix 330 may have a certain range of water absorption. Specifically, the high-absorbency matrix may have a water absorption of 10 g / g to 500 g / g, specifically 50 g / g to 200 g / g, but is not limited thereto. This means that the high-absorbency matrix 330 can absorb 10 g to 500 g of water, preferably 50 g to 200 g of water per 1 g of the high-absorbency matrix. The higher the water absorption of the high-absorbency matrix 330, the longer the cooling effect can be. However, if the water absorption exceeds 500 g / g, the fluidity of the high-absorbency matrix 330 increases, making it difficult to maintain its shape and unable to provide effective cooling. In addition, if the water absorption of the high-absorbency matrix 330 is less than 10 g / g, the amount of heat absorbed according to the pouch exterior temperature is significantly reduced, and the effect of suppressing a sudden change in the module interior temperature may be low and inefficient.

[0059] Additionally, the highly absorbent matrix 330 may further include thermally conductive fillers 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. 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] In addition, 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 so as 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 transmit external heat to the highly absorbent matrix 330 inserted therein. For example, the pouch 310 may be composed 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 degree of strength, and is resistant to external forces.

[0065] In addition, the internal resin layer is located on the inner surface of the metal layer and can function to prevent the water impregnated in the highly absorbent matrix 330 from reacting with the metal layer of the pouch. For this purpose, the internal resin layer can include a crosslinked polyolefin resin. The crosslinked polyolefin resin has low hygroscopicity and can suppress the intrusion of the water impregnated in the highly absorbent matrix, so that the expansion or erosion of the internal resin layer due to this may not occur. Here, the polyolefin resin may have a crosslinking degree of 10 to 70%, specifically, a crosslinking degree of 30 to 50%. In addition, the polyolefin resin may be any one or more selected from the group consisting of polypropylene (PP) and polyethylene (PE), and the crosslinked polyolefin resin may specifically include crosslinked polyethylene, crosslinked polypropylene, or a mixture thereof, more specifically, crosslinked polypropylene.

[0066] In addition, since the outer resin layer needs to have excellent resistance against the external environment to protect the heat absorbing pack 30 from the outside, it is required to have excellent tensile strength and weather resistance relative to the thickness, and 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 of two or more, and ONy (oriented nylon film) may be used in addition.

[0067] In addition, when water impregnated in the highly absorbent matrix 330 is vaporized by external heat, a difference in gas pressure occurs between the inside and outside of the pouch, and the pouch 310 includes a venting inducing part 313 that discharges water vapor vaporized by the difference in pressure to the outside. To this end, the venting inducing part 313 may be provided on one side edge of the pouch 310 to facilitate the discharge of 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 between the pressure inside and outside the endothermic pack 30, the venting inducing unit 313 does not exhaust gas (i.e., exhaust water vapor) and blocks the inflow of external substances into the endothermic pack 30, but when the pressure difference between the inside and outside of the endothermic pack 30 is 0.1 atm or more, water vapor is exhausted through the venting inducing unit 313 due to the air pressure difference. After that, when the pressure difference between the inside and outside of the endothermic pack 30 is 0.1 atm or less or disappears due to a certain amount of exhaust, the process of blocking the exhaust of water vapor again can be performed reversibly.

[0069] Also, the venting induction part 313 may have a structure in which a first layer having pores and a second layer having no pores are laminated, and the first layer and the second layer may be made of the same material containing polytetrafluoroethylene (PTFE). Polytetrafluoroethylene (PTFE) has excellent heat resistance and hydrophobic properties, and therefore has the advantage of being suitable as a material for the venting induction part.

[0070] In addition, the first layer may have a structure in which pores are formed, whereas the second layer may have a structure in which pores are not formed, in the venting induction portion 313. Specifically, the first layer may have a structure in which open pores are formed so that the inside and outside are connected, and the second layer may have a shape in which bends are formed on the surface but pores are not formed, and since the second layer is made of a PTFE material, gas can be discharged through fine gaps formed between the polymers.

[0071] In addition, the outer resin layer, the metal layer and the inner resin layer of the pouch 310 have a state in which a portion where the venting induction part 313 is disposed is perforated, and the venting induction part 313 is disposed at this portion and the edge of the venting induction part is pressurized at high temperature, so that the venting induction part 313 can be stably attached to the inner side surface of the pouch 310. More specifically, when the venting induction part 313 is disposed at the perforation part of the pouch 310 and the edge of the venting induction part 313 is pressurized at high temperature, the inner resin layer of the pouch 310 melts into the inside of the pores of the first layer of the venting induction part, so that the venting induction part 313 can be stably attached to the inner side surface of the pouch. As a result, gas (e.g., water vapor) formed inside the pouch 310 can be discharged to the outside through the first and second layers of the venting induction part 313. For this reason, the perforation part of the pouch 310 may have an area smaller than the area of ​​the venting induction part 313.

[0072] Meanwhile, polytetrafluoroethylene (PTFE) has a melting point of 327°C, which is significantly different from the melting point of polypropylene (PP), which is mainly used as the inner resin layer of the pouch, which is about 160°C. Therefore, when heating and pressurizing the venting induction part 313 made of polytetrafluoroethylene (PTFE) material to attach it to the inner resin layer made of polypropylene (PP), if the heating temperature is at a temperature at which polytetrafluoroethylene (PTFE) melts, the polypropylene (PP) may be damaged. On the other hand, if the polypropylene (PP) is heated to a temperature at which it melts but not damaged, polytetrafluoroethylene (PTFE) does not melt, so they are difficult to bond to each other.

[0073] Therefore, in the present invention, a structure is used in which venting inducing portion 313 is attached to the pouch so that the first layer having pores contacts the internal resin layer of the pouch. When the overlapping portion of pouch 310 and venting inducing portion 313 is heated and pressurized to a high temperature in order to attach venting inducing portion 313 to the pouch, a portion of the internal resin layer hardens in a state where it is melted 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 meet 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 within 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, whereas if the thickness exceeds 50 mm, the thickness of the battery module increases and the energy density may be significantly reduced.

[0076] The heat absorption pack 30 according to the present invention, having the above-mentioned configuration, can not only absorb a large amount of heat in the vicinity when heat is generated inside the module, but also uniformly supply the heat to the highly absorbent matrix 330, thereby preventing damage to the heat absorption pack 30 caused by heat generated inside the module. Therefore, when the heat absorption pack 30 is provided in a secondary battery module, it can prevent the ambient temperature of the secondary battery from changing suddenly, thereby improving the performance and stability of the secondary battery according to the ambient temperature.

[0077] <Secondary battery module> Further, in one embodiment, the present invention provides There is provided a secondary battery module including 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 of the present invention includes a plurality of battery cells 20 and is equipped with the heat absorption pack 30 of the present invention described above together with these battery cells, and has the advantage of being excellent in stability against the temperature of the battery cells 20, since it can prevent a sudden increase in temperature inside the module.

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

[0082] For this, the housing member 10 may be composed of a bottom member 11, a side wall member 12, etc. 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 an upper end of the side wall member 12 to protect an upper end of the battery cell 20. In addition, a gas venting member 17 may be included 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 be configured in such a way that it 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 applicable to a lithium secondary battery, and specifically, the battery cell 20 may have a shape such as a square type, a pouch type, a cylindrical type, etc. As one example, the battery cell 20 may be a square or pouch type 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 member 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 member 12.

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

[0090] As another example, a heat absorption pack 30b may be inserted between the battery cells 20. Specifically, the heat absorption pack 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 aligned 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 disposed so that the venting inducing portion is exposed to the upper portion 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 the surface is vertical with respect to the bottom surface of the module, i.e., the bottom member 11, and at this time, the venting inducing portion provided on one side edge of the endothermic pack may be disposed adjacent to the upper portion of the module, for example, the cover member 13 and / or the gas venting member 17 of the module.

[0093] The present invention will now be described in more detail 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 heat-absorbing pack

[0096] A rectangular aluminum (Al) sheet was prepared as a heat dispersion substrate. The aluminum sheet was folded in half at a point that was half the length of the long axis of the aluminum sheet, and the two sides adjacent to the folded side among the three open sides of the folded aluminum sheet were sealed. Then, two pinhole lines were formed on the remaining side that was not sealed, so that 10 pinholes were formed in one line along the edge. Then, a superabsorbent fiber was inserted inside the sealed aluminum (Al) sheet, and water was injected to impregnate the superabsorbent fiber with water. At this time, the water was impregnated at 10 g per 1 g of superabsorbent fiber (component: acrylic acid copolymer). Then, the inside was evacuated, and the open side of the aluminum (Al) sheet was sealed so that the pinhole was located inside the sealed part (e.g., the unsealed area), and an aluminum bag (Al bag) in the form of a bag formed of an aluminum sheet containing superabsorbent fiber impregnated with water was manufactured.

[0097] Separately, an aluminum pouch was prepared, 9 cm wide and 12 cm long, including an aluminum layer, a polypropylene (PP) layer located on the outside of the aluminum layer, and a polyethylene (PE) layer with a cross-linking degree of 40±2% located on the inside of the aluminum layer. The aluminum bag prepared above was inserted into the prepared aluminum pouch, and the inside of the pouch was made into a vacuum state, and the pouch's insertion port was sealed to prepare a heat-absorbing pack.

[0098] In this case, the pouch is provided with a venting induction portion on one side edge, and the venting induction 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 it is arranged to face the inside of the pouch.

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

[0100] Example 2: Manufacture of heat-absorbing 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 dispersion substrates and inserted inside the prepared pouch. Next, highly absorbent fibers were inserted between the two inserted aluminum (Al) sheets, and water was injected to impregnate the highly absorbent fibers. At this time, the water was impregnated at 10 g per 1 g of highly absorbent fibers (component: acrylic acid copolymer). After that, the inside of the pouch was evacuated and the pouch's inlet was sealed to produce a heat absorbing pack.

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

[0103] <Comparative Example 1. Manufacture of heat-absorbing pack>

[0104] A heat absorbing pack was manufactured in the same manner as in Example 1, except that a rectangular aluminum (Al) sheet as a heat dissipating substrate was not used and heat absorbing fibers were directly inserted inside the pouch.

[0105] <Comparative Example 2. Manufacture of heat-absorbing pack>

[0106] A heat absorbing pack was manufactured in the same manner as in Example 1, except that the aluminum bag (Al bag) made of a rectangular aluminum (Al) sheet as a heat dissipation 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 a source of heat, and the temperatures of the side heated by the torch (i.e., the heated side) and the rear side were measured during heating.

[0111] After the heating with the torch was completed, the endothermic pack was cooled, disassembled, and visually evaluated for damage to the highly absorbent fiber inserted in the pouch inside the endothermic pack.

[0112] The results are shown in Table 1 below and in Figs. 5 to 9. Damage to the superabsorbent fiber is indicated by ◯ if it was damaged, and × if it was not damaged.

[0113] [Table 1]

[0114] As shown in Table 1 and FIGS. 5 to 9, it is clear that the heat-absorbing packs according to the examples of 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 heat absorption pack of the embodiment has the highest temperature in the center, which is directly heated by the torch, in the case of the heating surface, followed by the top and bottom, while in the case of the rear surface, the temperature is highest in the order of top > center > bottom. This means that the water contained inside the heat absorption 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 heat absorption pack.

[0116] In addition, it was confirmed that the temperatures of the heating surface and the rear surface of the heat absorption pack of the embodiment are generally lower than those of the heat absorption pack of the comparative example. This means that when a heat dispersion substrate is introduced into the pouch, the heat from the outside can be dispersed more effectively to the highly absorbent fiber, and when pinholes are introduced into the heat dispersion substrate, the evaporated water vapor is selectively released to the outside, thereby increasing the latent heat of water.

[0117] Furthermore, as shown in Fig. 7, it was confirmed that in the heat absorption pack of the embodiment, the superabsorbent fiber inserted inside the pouch uniformly absorbs the heat around the pouch, and no internal damage occurs to the superabsorbent fiber. In contrast, referring to Figs. 8 and 9, the heat absorption pack of Comparative Example 1 does not have a heat dispersion base material, i.e., an aluminum (Al) sheet, between the pouch and the superabsorbent fiber, or does not meet the thickness conditions of the present invention, and not only is it unable to fully absorb the thermal energy inside the module, but internal damage occurs to both the superabsorbent fiber and the pouch when absorbing heat, showing that the heat absorption of the heat absorption pack is not stable.

[0118] From these results, it can be seen that the endothermic pack of 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 to prevent damage to the endothermic pack during the heat absorption process, thereby making it possible to more stably control 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 may make various modifications and changes to the present invention without departing from the spirit and technical scope of the present invention as described in the claims below.

[0120] Therefore, the technical scope of the present invention is not limited to the contents 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 component 15: Rear member 16: Partition wall material 17: Gas venting parts 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 disposed on the outer surface of the battery cell 30b: A heat absorbing pack disposed between a plurality of rows of aligned battery cells. 40: Heat sink

Claims

1. A highly absorbent matrix; a heat dispersing substrate disposed on at least one surface of the highly absorbent matrix; a pouch into which the highly absorbent matrix having the heat dispersing substrate disposed thereon is inserted; The highly absorbent matrix is ​​immersed in water. The heat dissipating substrate includes a plurality of pinholes on one side edge of the heat dissipating substrate.

2. The pouch includes a venting guide 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 disposed on the same side as the venting induction portion.

3. 2. The heat absorption 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 absorption 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 absorption 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 highly absorbent matrix comprises at least one 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 sulfuric acid, 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 a heat absorption pack is 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 heat absorption pack is inserted such that a surface of the heat absorption pack is vertical with respect to a bottom surface of the secondary battery module, and the venting induction portion of the heat absorption pack is positioned at an upper portion.

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