Battery module

Abstract

Provided is a battery module provided with a case, a plurality of unit cells disposed in the case, and a heat absorbing member, the energy density of the unit cells being 200 Wh / L or more, the heat absorbing member being provided between the case and the unit cells and / or between the plurality of unit cells, the heat absorbing amount Q of the heat absorbing member from 150 DEG C to 350 DEG C being 500 J / cm < 3 > or more, and the heat absorbing amount Q of the heat absorbing member from 150 DEG C to 350 DEG C being 500 J / cm < 3 > or more. And the thermal conductivity lambda of the heat absorbing member is 0.8 W / mK or more. According to the present invention, it is possible to provide a battery module in which the temperature does not readily rise at the initial stage of an abnormality of a single battery or during a certain period after the occurrence of the abnormality.

Description

[0001] This application is a divisional application of the Chinese patent application with application date of June 5, 2020, application number 202080040386.2, and invention name “Battery Module”. Technical Field

[0002] The present invention relates to a battery module including a specific heat absorbing member. Background Art

[0003] In recent years, electric vehicles have become popular from the perspective of environmental issues. Electric vehicles are equipped with batteries such as lithium-ion secondary batteries. Batteries used in electric vehicles need to have high output and large capacity. Single batteries are not enough, and battery modules composed of multiple single batteries and battery packs composed of multiple battery modules are used.

[0004] When a single cell suffers an abnormal situation such as an internal short circuit or external damage, it will generate heat, which will be transmitted to its adjacent single cells, causing the temperature to rise and there is a problem of thermal runaway of the entire battery.

[0005] From the perspective of improving this problem, Patent Document 1 records a thermal runaway prevention sheet, which contains at least one of a mineral powder and a flame retardant, starts an endothermic reaction at 100 to 1000°C, undergoes a specific structural change through the endothermic reaction, and records that the thermal runaway prevention sheet can exhibit insulation properties to prevent continuous thermal runaway of adjacent batteries.

[0006] Prior Art Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2018-206605 Summary of the invention

[0008] Problems to be solved by the invention

[0009] However, although the above-mentioned thermal runaway prevention sheet can suppress heat transfer to adjacent batteries to a certain extent through its insulation performance, there is still room for improvement from the perspective of sufficiently cooling the rapid heat generation at the initial stage of abnormality. In addition, when the sheet has insulation performance, it may cause a significant temperature rise after the heat absorbent is consumed.

[0010] Therefore, an object of the present invention is to provide a battery module that can effectively suppress a temperature rise in the early stage of the abnormality and in a certain period after the occurrence of the abnormality even when an abnormality occurs in a single cell.

[0011] Means for solving problems

[0012] The present inventors have conducted intensive studies and have found that the above-mentioned problems can be solved by a battery module including a heat absorbing member having a heat absorption amount and a thermal conductivity within a specific range, thereby completing the present invention.

[0013] The present invention provides the following [1] to [8].

[0014] [1] A battery module comprising a housing, a plurality of cells arranged in the housing, and a heat absorbing member, wherein the energy density of the cells is 200 Wh / L or more, the heat absorbing member is arranged between the housing and the cells and / or between the cells, and the heat absorbing member has a heat absorption amount Q of 500 J / cm from 150° C. to 350° C. 3 The heat absorbing member has a thermal conductivity λ of 0.8 W / mK or more.

[0015] [2] The battery module according to [1] above, wherein the heat absorbing member is arranged so that the heat absorption amount Qs per unit area relative to the surface of the single battery is 50 J / cm 2 above.

[0016] [3] The battery module according to [1] or [2], wherein the product of the thermal conductivity λ and the heat absorption Q (λ×Q) is 1000 W·J / mK·cm 3 above.

[0017] [4] The battery module according to any one of [1] to [3] above, wherein the heat absorbing member contains a resin and a filler.

[0018] [5] The battery module according to [4] above, wherein the resin is silicone rubber.

[0019] [6] The battery module according to [4] or [5] above, wherein the filler contains at least aluminum hydroxide.

[0020] [7] The battery module according to [6] above, wherein the aluminum hydroxide contains small-particle aluminum hydroxide having an average particle size of 2 μm or less and large-particle aluminum hydroxide having an average particle size of more than 2 μm.

[0021] [8] The battery module according to [6] or [7] above, wherein the heat absorbing member contains 100 parts by mass or more of aluminum hydroxide per 100 parts by mass of the resin.

[0022] Effects of the Invention

[0023] According to the present invention, it is possible to provide a battery module capable of effectively suppressing a temperature increase at the initial stage of an abnormality and within a certain period after the occurrence of the abnormality. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1It is a cross-sectional view schematically showing an example of arrangement of heat absorbing members in a battery module.

[0025] Figure 2 It is a perspective view of one embodiment of a single cell.

[0026] Figure 3 It is a cross-sectional view schematically showing another example of the arrangement of the heat absorbing member of the battery module.

[0027] Figure 4 It is a cross-sectional view schematically showing another example of the arrangement of the heat absorbing member of the battery module.

[0028] Figure 5 It is a cross-sectional view schematically showing another example of the arrangement of the heat absorbing member of the battery module.

[0029] Figure 6 It is an explanatory diagram showing an example of a state in which a battery module is assembled.

[0030] Figure 7 It is an explanatory diagram showing another example of a state in which a battery module is assembled.

[0031] Figure 8 It is an explanatory diagram showing an example of a state in which a battery pack is assembled. DETAILED DESCRIPTION

[0032] The present invention is a battery module, which comprises a housing, a plurality of cells with an energy density of 200Wh / L or more arranged in the housing, and a specific heat absorbing component arranged between the housing and the cells and / or between the plurality of cells. The heat absorbing component has a heat absorption Q of 500 J / cm from 150°C to 350°C. 3 The heat absorbing member has a thermal conductivity λ of 0.8 W / mK or more.

[0033] The embodiments of the present invention are described with reference to the accompanying drawings. The present invention is not limited to the contents of the following drawings.

[0034] Figure 1 The battery module 10 includes a case 11 , a plurality of cells 12 arranged in the case 11 , and a heat absorbing member 13 provided between the case 11 and the cells 12 .

[0035] The single cell 12 is a constituent unit of a lithium-ion secondary battery or the like, and is generally composed of an outer film and a battery element (not shown) sealed in the outer film. Examples of the battery element include a positive electrode, a negative electrode, a separator, an electrolyte, and the like. Figure 2As shown, the cell 12 is a flat body whose thickness is thinner than its width, the positive electrode 12a and the negative electrode 12b are exposed to the outside, and the flat surface 12c is formed to be thicker than the end portion 12d to be crimped.

[0036] The energy density of the cell 12 is 200Wh / L or more. Thus, the cell 12 can be miniaturized by having a high energy density. On the other hand, when an abnormality such as a short circuit occurs due to the high energy density, there is a concern that the temperature may easily rise, but as described later, the heat absorbing member 13 has a certain value or more of the amount of heat absorbed Q and the thermal conductivity λ, so it is easy to suppress the temperature rise of the cell 12. The higher the energy density of the cell 12, the better, but it is usually 700WL / L or less.

[0037] In the housing 11, a plurality of cells 12 are stacked with their flat surfaces in contact with each other, and each cell 12 is arranged so that its length direction is in the up-down direction of the housing 11. The housing 11 is a member that covers the cells 12 together. The housing 11 is made of a material that has a strength that can support a plurality of cells 12 and does not deform due to the heat generated by the cells 12, and aluminum is preferably used in consideration of the balance between strength, weight, heat resistance, etc.

[0038] The heat absorbing member 13 is provided between the lower surface 11a of the case and the lower end surface 12a of the single cell 12. The heat absorbing member 13 can effectively suppress the temperature rise of the battery module at the initial stage of the abnormality and for a certain period from the occurrence of the abnormality when an abnormality such as an internal short circuit or damage from the outside occurs in the single cell 12. It is presumed that this is because the amount of heat absorbed Q when the heat absorbing member 13 is heated from 150°C to 350°C is greater than a certain value, thereby suppressing the temperature rise of the single cell 12, and because the thermal conductivity λ is greater than a certain value, it is easy to effectively transfer the heat generated by the single cell 12 to the case 11. It is presumed that the thermal conductivity λ being greater than a certain value suppresses the temperature rise in the initial stage of the abnormality, and the amount of heat absorbed Q being greater than a certain value suppresses the continuous temperature rise in the initial stage of the abnormality and for a certain period from the occurrence of the abnormality.

[0039] Figure 1 , the heat absorbing member 13 is provided between the lower surface 11a of the housing 11 and the lower end surface 12a of the cell 12, but the arrangement of the heat absorbing member 13 is not limited to this, and the heat absorbing member 13 may be provided in at least one space between any surface of the housing 11 and the surface of the cell 12 close to the surface. Specifically, the heat absorbing member 13 may be provided between the side surface 11c of the housing and the flat surface 12c of the cell 12, between the upper surface 11b of the housing and the upper end surface 12b of the cell 12, and the like.

[0040] Alternatively, the heat absorbing member 13 may be disposed in the entire space between all surfaces of the housing 11 and the surfaces of the single cells 12 close to the surfaces (ie, the entire space inside the housing 11). Figure 3 As shown, the heat absorbing member 13 may be arranged so as to surround the entirety of the plurality of cells 12. In this case, the heat generated from the cells 12 can be reduced more effectively.

[0041] Above Figure 1 and 3 FIG. 1 shows a method in which the heat absorbing component 13 is disposed between the housing 11 and the battery cell 12, but the heat absorbing component 13 may also be disposed between the housing 11 and the battery cell 12. Figure 4 As shown, the heat absorbing member 13 is provided between the plurality of cells 12 (cell spaces 14). In this case, the heat absorbing member 13 can suppress the temperature rise of the cell 12 in which the abnormality occurs, and it is difficult for the high-temperature heat to be transferred to the adjacent cells 12, so that the expansion of the abnormality can be suppressed. Thus, the temperature rise can be effectively suppressed at the initial stage of the abnormality and for a certain period of time after the abnormality occurs.

[0042] In addition, the heat absorbing member 13 may be provided between the housing 11 and the battery cell 12 and between the plurality of battery cells 12 . Figure 5 In the embodiment, a heat absorbing component 13 is provided in the entire space between multiple single cells 12 and between all surfaces of the shell 11 and the surface of the single cell 12 close to the surface (in other words, a heat absorbing component 13 is provided in all spaces inside the shell 11), which can effectively suppress the temperature rise of the single cell 12.

[0043] exist Figure 1 It is described in the literature that the cell 12 is a laminated cell using an exterior film, but in addition to the laminated cell, a square cell or a cylindrical cell may be used.

[0044] In addition, Figure 1 The embodiment in which a plurality of cells 12 are stacked in contact with each other is shown in FIG. 1 , but functional components such as an absorbent material and a cooling fin may be provided between the cells 12 .

[0045] For example, Figure 6 As shown, a sheet-shaped absorbent material may be provided between the single cells 12 and the single cells 12. By providing the absorbent material 15, the impact absorption can be improved, and the abnormality of the single cell 12 caused by external impact, etc. can be reduced. In addition, although not shown, a submodule formed by stacking a plurality of single cells 12, preferably a submodule formed by stacking two single cells 12, can also be produced, and the absorbent material 15 can be provided between the submodules.

[0046] Specific examples of the absorbent material 15 include foam, low-hardness rubber, etc. Only one absorbent material 15 may be provided, or two or more absorbent materials may be provided.

[0047] In addition, it is preferable to arrange the absorbent material 15 and the heat absorbing member 13 in parallel between the cells 12, or to arrange the heat absorbing member 13 between the absorbent material 15 and the cells 12. In this way, the occurrence of abnormality of the cells 12 can be reduced, and even when an abnormality occurs, the temperature rise of the cells 12 can be suppressed, thereby improving the stability of the battery module.

[0048] When arranging the absorbing material 15 and the heat absorbing member 13 in parallel between the cells 12, it is preferable to arrange the heat absorbing member 13 at a location where damage is more likely, and arrange the absorbing material 15 at other locations. For example, an embodiment is one in which the absorbing material 15 is arranged near the center of the cell 12, and the heat absorbing member 13 is arranged near the outer edge or corner of the cell 12.

[0049] In addition, if Figure 7 As shown, cooling fins 16 may be provided between the single cells 12 and the single cells 12. The cooling fins 16 are components including a sheet and a snap-fit ​​portion provided along the length direction at both ends of the sheet, and the cross section is an H-shape. In addition, although not shown, a submodule formed by stacking a plurality of single cells 12, preferably a submodule formed by stacking two single cells 12, may be manufactured, and cooling fins 16 may be provided between the submodules.

[0050] The cooling fins 16 are preferably made of metal, more preferably aluminum. The cooling fins 16 can easily suppress a rise in the temperature of the battery cells 12 .

[0051] Only one cooling fin 16 may be provided, or two or more cooling fins 16 may be provided.

[0052] A heat dissipating adhesive or a heat dissipating sheet may be provided between the cooling fins 16 and the single cells 12. Among them, it is preferable to arrange the heat absorbing member 13 between the cooling fins 16 and the single cells 12. Thus, the heat generated in the single cells 12 is effectively cooled by the heat absorbing member 13 and the cooling fins 16. In addition, the heat generated in the single cells 12 is transferred to the surface of the housing through the engaging portion between the heat absorbing member 13 and the cooling fins 16, and the heat is dissipated and cooled more effectively. In addition, the structure of the cooling fins 16 is not limited to the above-mentioned form.

[0053] (Heat absorbing components)

[0054] The heat absorbing component of the present invention has a heat absorption capacity Q of 500 J / cm from 150°C to 350°C. 3 The heat absorption Q is the amount of heat absorbed from 150°C to 350°C when the heat absorbing component is heated at a certain temperature increase rate. If the heat absorption Q is less than 500 J / cm 3 , it is difficult to suppress the temperature rise of the battery module. The heat absorption Q is preferably 1000 J / cm3 More preferably 1500 J / cm 3 More preferably, 2000 J / cm 3 The higher the heat absorption Q, the better, but it is usually 4000J / cm 3 the following.

[0055] The amount of heat absorbed Q by the heat absorbing member can be calculated from the amount of heat absorbed Qf (J / cm 3 ) and the volume ratio of the filler in the heat absorbing component. The heat absorption amount Qf of the filler is the heat absorption amount of the filler from 150°C to 350°C. When the volume ratio of the filler to the entire heat absorbing component is X volume %, it can be calculated by the formula: the heat absorption amount Q of the heat absorbing component = the heat absorption amount Qf of the filler × X / 100. The heat absorption amount Qf of the filler is determined by TG-DTA measurement.

[0056] The endothermic amount Qf can be measured by a TG-DTA apparatus using a φ5 mm aluminum pan in a nitrogen atmosphere (flow rate of 50 ml / min) at a temperature increase rate of 5°C / min from 25°C.

[0057] In addition, when it is difficult to measure the endothermic quantity Qf of the filler, the endothermic quantity Q of the heat absorbing member may be directly measured by TG-DTA. In this case, a test piece of the heat absorbing member having a disk shape of 5 mm in diameter and a thickness of 2 mm is prepared, and the test piece is arranged so as to be in close contact with the bottom surface of a 5 mm in diameter aluminum pan, and the temperature is measured at a temperature increase rate of 5°C / min from 25°C in a nitrogen atmosphere (flow rate of 50 ml / min).

[0058] The thermal conductivity λ of the heat absorbing member is 0.8 W / mK or more. If the thermal conductivity is less than 0.8 W / mK, heat transfer from the heat absorbing member to the housing or the like is difficult to occur, and therefore the temperature rise of the abnormal battery module is likely to increase. The thermal conductivity λ of the heat absorbing member is preferably 1.0 W / mK or more, and more preferably 1.5 W / mK or more. In addition, the upper limit of the thermal conductivity is preferably 4.0 W / mK or less, more preferably 3.4 W / mK or less, and further preferably 2.8 W / mK or less.

[0059] The thermal conductivity λ can be measured by a method in accordance with ASTM D5470-06.

[0060] Specifically, for the heat absorbing member, samples with a thickness in the range of 0.5 mm to 5.0 mm (preferably 1.0 mm to 3.0 mm) are prepared, and thermal resistance is measured at three different thicknesses to calculate thermal conductivity. For samples of different thicknesses, samples of different thicknesses may be prepared, or a single sample may be measured with varying compression rates.

[0061] The product of thermal conductivity λ and heat absorption Q (λ×Q) is preferably 1000 W·J / mK·cm 3 More preferably, 2000 W·J / mK·cm 3 More preferably, 3000 W·J / mK·cm 3 Above, and preferably 16000 W·J / mK·cm 3 the following.

[0062] When both the amount of heat absorbed Q and the thermal conductivity λ of the heat absorbing member are large, the temperature rise of the battery module can be more effectively suppressed. The large amount of heat absorbed Q reduces the temperature of the single cell, and the large thermal conductivity λ facilitates the transfer of heat generated from the single cell to the housing, etc. Therefore, it is believed that the synergistic effect of these various effects can effectively suppress the temperature rise of the battery module.

[0063] The heat absorbing component can be arranged such that the heat absorption per unit area Qs is preferably 50 J / cm 2 More preferably 100 J / cm 2 More preferably, 200 J / cm 2 In this way, if the amount of heat absorbed Qs is above a certain value, it is easy to suppress the temperature rise of the single cell. There is no particular upper limit on the amount of heat absorbed Qs, for example, 1000 J / cm 2 When the maximum thickness of the heat absorbing member disposed on the surface of the single cell is set to Y (cm), the heat absorption amount per unit area Qs is calculated by Qs = Q × Y. Furthermore, when the heat absorbing member is provided with a uniform thickness relative to the surface of the single cell, the average thickness and the arbitrary thickness of the heat absorbing member are equal to the maximum thickness Y.

[0064] (Heat absorbing components)

[0065] The heat absorbing member of the present invention contains a resin and a filler. Hereinafter, each component of the heat absorbing member will be described.

[0066] <Resin>

[0067] The resin contained in the heat absorbing member is not particularly limited, and examples thereof include rubber and elastomer.

[0068] Examples of the rubber include silicone rubber, acrylic rubber, nitrile rubber, isoprene rubber, polyurethane rubber, ethylene-propylene rubber, styrene-butadiene rubber, butadiene rubber, fluororubber, butyl rubber, etc. When these rubbers are used, they may be crosslinked or may remain uncrosslinked (i.e., uncured).

[0069] In addition, as the elastomer, thermoplastic elastomers such as polyester thermoplastic elastomers and polyurethane thermoplastic elastomers, and thermosetting elastomers formed by curing a mixed liquid polymer composition composed of a main agent and a curing agent can also be used. For example, a polyurethane elastomer formed by curing a polymer composition containing a polymer having a hydroxyl group and an isocyanate can be exemplified.

[0070] The resin contained in the heat absorbing member is preferably silicone rubber among the above resins. By using silicone rubber, it is easy to fill the filler with a high amount, and it is easy to adjust the thermal conductivity and the amount of heat absorption to desired values. The silicone rubber is preferably formed of liquid silicon, and specifically, the heat absorbing member is preferably formed of a heat absorbing composition containing liquid silicon and a filler.

[0071] Liquid silicon may be non-curable silicon or reaction-curable silicon, but reaction-curable silicon is preferably used. Here, liquid means being in a liquid state at room temperature (25° C.).

[0072] As reaction-curable silicone, for example, there can be mentioned addition reaction-curable silicone, free radical reaction-curable silicone, condensation reaction-curable silicone, ultraviolet or electron beam-curable silicone, and moisture-curable silicone. Among the above, the reaction-curable silicone is preferably an addition reaction-curable silicone. As the addition reaction-curable silicone, an addition reaction-curable silicone comprising an alkenyl-containing organopolysiloxane (main agent) and a hydrogen organopolysiloxane (curing agent) is more preferably used.

[0073] The content of the silicone rubber based on the entire resin contained in the heat absorbing member is preferably 80% by mass or more, more preferably 95% by mass or more, and even more preferably 100% by mass.

[0074] <Filling agent>

[0075] The heat absorbing member in the present invention contains a filler. The filler is not particularly limited as long as it allows the heat absorption amount Q and thermal conductivity λ of the heat absorbing member to fall within the above-mentioned predetermined ranges.

[0076] Although it depends on the type of filler described below, the content of the filler is preferably 50 to 1500 parts by mass, more preferably 100 to 1000 parts by mass, based on 100 parts by mass of the resin.

[0077] Examples of the filler include alumina, boron nitride, aluminum nitride, silicon carbide, aluminum hydroxide, and magnesium hydroxide. Among these, the filler preferably contains at least aluminum hydroxide from the viewpoint of easily adjusting the heat absorption amount Q and thermal conductivity λ of the heat absorbing member to a desired range.

[0078] Aluminum hydroxide may be used alone, but in order to increase the amount of heat absorption Q and thermal conductivity λ by increasing the filling amount in the heat absorbing member, it is preferred to use two or more aluminum hydroxides having different average particle sizes. From this viewpoint, as aluminum hydroxide, it is preferred to contain small-particle aluminum hydroxide having an average particle size of 2 μm or less and large-particle aluminum hydroxide having an average particle size of more than 2 μm. As the above-mentioned small-particle aluminum hydroxide, it is preferred that the average particle size is 1 μm or less. In addition, the average particle size can be measured by an electron microscope or the like.

[0079] From the viewpoint of increasing the filling amount in the heat absorbing member, the amount of small-particle aluminum hydroxide relative to large-particle aluminum hydroxide (small-particle aluminum hydroxide / large-particle aluminum hydroxide) is preferably 0.1 to 2, more preferably 0.1 to 0.8, and even more preferably 0.2 to 0.5.

[0080] In addition, from the viewpoint of increasing the filling amount in the heat absorbing member, the large-particle-size aluminum hydroxide preferably includes a first large-particle-size aluminum hydroxide having an average particle size of greater than 2 μm and less than 20 μm and a second large-particle-size aluminum hydroxide having an average particle size of greater than 20 μm and less than 100 μm. Here, the amount of the first large-particle-size aluminum hydroxide relative to the second large-particle-size aluminum hydroxide (first large-particle-size aluminum hydroxide / second large-particle-size aluminum hydroxide) is preferably 0.1 to 2, more preferably 0.2 to 1.5, and even more preferably 0.3 to 1.

[0081] From the viewpoint of increasing the heat absorption amount Q and thermal conductivity λ of the heat absorbing member, the amount of aluminum hydroxide is preferably 50 parts by mass or more, more preferably 100 parts by mass or more, further preferably 300 parts by mass or more, further preferably 500 parts by mass or more, and preferably 1500 parts by mass or less, relative to 100 parts by mass of the resin.

[0082] From the viewpoint of increasing the amount of heat absorbed Q and the thermal conductivity λ, the content of aluminum hydroxide based on the total amount of filler is preferably 10% by mass or more, more preferably 70% by mass or more, and further preferably 100% by mass. In addition, when aluminum hydroxide and fillers other than aluminum hydroxide are used as fillers, from the viewpoint of adjusting the thermal conductivity λ to a higher value, the filler preferably contains aluminum hydroxide and aluminum oxide, and preferably consists only of aluminum hydroxide and aluminum oxide. In this case, the amount of aluminum hydroxide relative to aluminum oxide (aluminum hydroxide / aluminum oxide) is preferably in the range of 0.05 to 7, more preferably 0.1 to 5.

[0083] The average particle size of aluminum oxide is not particularly limited, but is preferably 0.5 to 150 μm, more preferably 1 to 100 μm.

[0084] The filler may be surface treated with a silane coupling agent or the like. By using a surface treated filler, the filling rate of the heat absorbing component can be increased. As the silane coupling agent, a known silane coupling agent may be used without particular limitation, and examples thereof include dimethyldimethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, vinyltrimethoxysilane, n-decyltrimethoxysilane, 3-isocyanatepropyltriethoxysilane, 3-(2-aminoethyl)aminopropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, glycidoxypropyltrimethoxysilane, and 3-phenylaminopropyltrimethoxysilane.

[0085] The heat absorbing member is formed of a heat absorbing composition containing a resin and a filler, preferably formed of a heat absorbing composition containing liquid silicon and a filler as described above. Here, the amount of the filler relative to the liquid silicon is the same as the amount of the filler relative to the resin as described above.

[0086] Furthermore, the endothermic composition may contain the above-mentioned silane coupling agent, and may also contain additives such as a dispersant, a flame retardant, a plasticizer, a curing retarder, an antioxidant, a colorant, and a catalyst.

[0087] (Battery Pack)

[0088] A battery pack may be formed using a plurality of battery modules provided with the above-described heat absorbing member.

[0089] Figure 8 The battery pack 20 includes a plurality of battery modules 10, a battery pack case 19 that accommodates the battery modules 10, and a heat dissipating material 18 disposed between the battery modules 10 and the battery pack case 19. The battery modules 10 are fixed to the battery pack case 19 via the heat dissipating material 18.

[0090] The battery pack case 19 can be formed of the same material as the case 11. In the battery pack 20, the heat generated from the battery module 10 can be released to the battery pack case 19 via the heat dissipation material 18. In this way, the heat generated in the single cell 12 is transferred to the heat absorbing member 13, the case 11, the heat dissipation material 18, and the battery pack case 19, and the heat is effectively dissipated to the outside. As the heat dissipation material 18, a known material such as silicone rubber containing a thermally conductive filler such as alumina, aluminum nitride, and boron nitride can be used, and the heat absorbing member of the present invention can also be used. If the heat absorbing member is used, the heat absorption amount Q and the thermal conductivity λ become above a certain value, thereby effectively reducing the temperature.

[0091] Example

[0092] Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

[0093] In this example, the evaluation was performed using the following method.

[0094] [Thermal conductivity]

[0095] The thermal conductivity of the heat absorbing member was determined by a method of measuring thermal resistance using a measuring device in accordance with ASTM D5470-06.

[0096] A heat absorbing member with a thickness of 1.0 mm was compressed at compression rates of 10% (thickness 0.9 mm), 20% (thickness 0.8 mm), and 30% (thickness 0.7 mm), and the thermal resistance at each compression rate (10 to 30%) was measured. A graph with the thickness on the horizontal axis and the thermal resistance on the vertical axis was prepared for these three thermal resistance values, and an approximate straight line at the three points was obtained by the least squares method. The slope of the approximate straight line became the thermal conductivity.

[0097] The thermal resistance was measured at 80° C. using LW-9389 manufactured by Long Win Science and Technology Corporation.

[0098] [Heat absorption Q]

[0099] The heat absorption amount Q of the heat absorption member is calculated based on the value of Qf after obtaining the heat absorption amount Qf of the filler contained in the heat absorption member from 150° C. to 350° C. as described in the specification.

[0100] The endothermic heat Qf was measured by a TG-DTA apparatus (Shimadzu Corporation, differential thermal and thermogravimetric simultaneous measuring apparatus "DTG-60"). In a nitrogen atmosphere, the sample was heated from 25°C to 600°C at a heating rate of 5°C / min, and the endothermic heat from 150 to 350°C was obtained.

[0101] [Example 1]

[0102] (1) Preparation of endothermic composition

[0103] An endothermic composition is prepared, which consists of the following components: 100 parts by mass of addition reaction curing type silicon composed of a main agent and a curing agent, 150 parts by mass of aluminum hydroxide with an average particle size of 1 μm, 150 parts by mass of aluminum hydroxide with an average particle size of 10 μm, 300 parts by mass of aluminum hydroxide with an average particle size of 54 μm, and 1 part by mass of a silane coupling agent.

[0104] (2) Nail penetration test

[0105] (Details of the battery used)

[0106] Type: 94Ah lithium-ion secondary battery

[0107] Shape: Square single cell, 125mm long, 173mm wide, 70mm thick

[0108] Weight: 2kg

[0109] Output voltage: 4V

[0110] Energy density: 355Wh / L

[0111] (test)

[0112] The surface of the square cell was coated with an endothermic composition so that after curing, it became an endothermic component having an average thickness (Y) as shown in Table 2. At this time, the endothermic composition was coated on all surfaces of the cell except one side (top surface (70 mm × 173 mm)). After coating, the endothermic composition was cured at 25°C for 24 hours to form an endothermic component. The two sides of the cell having the endothermic component thus prepared (the two largest surfaces on the surface of the cell) were clamped with two aluminum plates (125 mm × 210 mm × 10 mm) corresponding to adjacent cells, and the ends were fixed with bolts to prepare a sample for the nail penetration test. The temperature change of the sample during the nail penetration test was measured. Regarding the temperature change, in order to measure the temperature of the cell in which an abnormality occurred, a thermocouple was arranged "between the cell and the endothermic component" and the "maximum cell temperature until 50 seconds had passed" was measured. Furthermore, another thermocouple was placed “between the aluminum plate and the heat absorbing member” corresponding to the surface of the cell in contact with the adjacent cell, and the external temperature was measured after 300 seconds.

[0113] The reason why the "maximum cell temperature until 50 seconds have passed" is measured by using a thermocouple disposed between the cell and the heat absorbing component is as follows. In this fire test, the temperature of the cell rises sharply immediately after the nail is inserted, and then the temperature tends to gradually drop. Since the initial temperature rise is extremely rapid, the temperature outside the heat absorbing component is affected by the amount of heat absorbed and the thermal conductivity of the heat absorbing component in addition to the time difference of heat transfer, so a temperature lower than the actual maximum temperature is detected, and the temperature of the abnormal cell cannot be accurately grasped. Therefore, it is necessary to measure the temperature inside the heat absorbing component. If the initial temperature rise of the abnormal cell can be suppressed to a low level, it can be expected that the influence of heat conduction on the surroundings through the path where it is difficult to sandwich a heat absorbing component such as a bus bar can be reduced.

[0114] On the other hand, the reason why the "external temperature after 300 seconds" is measured by the thermocouple disposed between the aluminum plate and the heat absorbing member is that after about 300 seconds, a thermally stable state is reached, and the temperature difference between the inside and outside of the heat absorbing member becomes a predetermined temperature that is affected by thermal conductivity, the amount of heat absorbed, etc. At this time, from the viewpoint of suppressing runaway of adjacent cells, it is useful to evaluate the temperature (external temperature) of the outside of the heat absorbing member, which corresponds to the surface in contact with the temperature of the adjacent cells.

[0115] The nail penetration test was conducted by piercing a nail (φ6 mm, tip angle 30°) from the side surface (surface area 70 mm×125 mm) of the cell to the center of the cell at a speed of 20 mm / sec.

[0116] The maximum cell temperature after 50 seconds from the time the nail penetrated the cell and the external temperature after 300 seconds were measured by a thermocouple and evaluated according to the following criteria.

[0117] 《Effect of suppressing initial temperature rise》

[0118] A··The maximum cell temperature after 50 seconds is 200°C or less

[0119] B··The maximum cell temperature after 50 seconds is greater than 200°C and less than 300°C

[0120] C··The maximum cell temperature after 50 seconds is greater than 300°C and less than 350°C

[0121] D··The maximum cell temperature after 50 seconds is greater than 350°C

[0122] 《Effect of suppressing temperature rise during the whole period》

[0123] A··After 300 seconds, the external temperature is 270°C or less

[0124] B. The external temperature after 300 seconds is greater than 270°C and less than 300°C

[0125] D··After 300 seconds, the external temperature is greater than 300°C

[0126] Comprehensive Evaluation

[0127] A··The initial and full-term results are both A

[0128] B··One of the initial and full-term results is B, and the other is A or B

[0129] C··At least one of the initial and full-term results is C, and the other is any one of A, B, and C

[0130] D··At least one of the initial and full-term results is D

[0131] [Examples 2 to 5, Comparative Example 3]

[0132] The endothermic composition was prepared in the same manner as in Example 1 except that the composition of the endothermic composition was changed as shown in Table 1, and the nail penetration test was performed.

[0133] [Comparative Example 1]

[0134] The nail penetration test was conducted in the same manner as in Example 1, except that aerogel (thickness 10 mm, thermal conductivity 0.017 W / mK) was used instead of the endothermic composition used in Example 1. The results are shown in Table 2.

[0135] [Comparative Example 2]

[0136] The nail penetration test was conducted in the same manner as in Example 1 except that the endothermic composition was not used.

[0137] Table 1

[0138]

[0139] Table 2

[0140]

[0141] *The heat absorption (J / cm2) in the table is the heat absorption when heated from 150°C to 350°C

[0142] From the results of the above examples, it can be seen that if a heat absorbing component having a heat absorption amount Q and a thermal conductivity λ of a certain value or more is used, even when an abnormality occurs in a single cell, the temperature rise can be suppressed at the initial stage of the abnormality and for a certain period from the occurrence of the abnormality. On the other hand, from the results of the comparative examples, it can be seen that it is difficult to suppress the temperature rise of the single cell when the heat absorption amount Q and the thermal conductivity λ of the heat absorption component are not above a certain value. Specifically, in Comparative Example 3, although the heat absorption amount Q is above a predetermined value specified in the present invention, the thermal conductivity λ is low, and the comprehensive evaluation is "D", which is a poor result. Therefore, it is necessary that both the heat absorption amount Q and the thermal conductivity λ are above a predetermined value.

[0143] In Examples 1 to 5, the endothermic amount Q was 1000 J / cm 3 The comprehensive evaluation of Examples 1, 3 to 5 with the above high values ​​is "B" or higher, and the heat absorption is 500 or more and less than 1000 J / cm 3 The comprehensive evaluation of Example 2 is "C", which shows that the temperature rise of the single cell can be further suppressed by adjusting the endothermic amount Q to the preferred range.

[0144] The heat absorbing members of Example 1 and Example 3 have the same composition, but different heat absorption amounts per unit area Qs. That is, the Qs of Example 1 is a relatively high value and is within the preferred range, which indicates that the overall evaluation is high and the temperature rise of the single cell is easily suppressed.

[0145] Description of Reference Numerals

[0146] 10 Battery Module

[0147] 11 Housing

[0148] 11a Lower surface

[0149] 11b Upper surface

[0150] 12 single battery

[0151] 12a Positive electrode

[0152] 12b Negative electrode

[0153] 12c Flat surface

[0154] 12d End

[0155] 13 Heat absorbing components

[0156] 14 Single battery room

[0157] 15 Absorbent Materials

[0158] 16 Cooling fins

[0159] 18 Heat dissipation materials

[0160] 19 Battery pack housing

[0161] 20 Battery Pack

Claims

1. A battery module comprising a housing, a plurality of flat cells arranged in the housing, and a heat absorbing member, The energy density of the single cell is above 200Wh / L. The heat absorbing component is disposed between the housing and the single cell and / or between a plurality of single cells. The heat absorbing component contains resin and filler, The resin is rubber or elastomer, The filler contains at least aluminum hydroxide, The heat absorption capacity Q of the heat absorption component from 150°C to 350°C is 500 J / cm 3 and the thermal conductivity λ of the heat absorbing component is greater than 0.8 W / mK. The product of the thermal conductivity λ and the heat absorption Q, λ×Q, is 1000W·J / mK·cm 3 above, The aluminum hydroxide contains small-particle aluminum hydroxide with an average particle size of less than 2 μm and large-particle aluminum hydroxide with an average particle size of more than 2 μm. The amount of the small-particle aluminum hydroxide relative to the large-particle aluminum hydroxide, that is, the small-particle aluminum hydroxide / large-particle aluminum hydroxide is 0.1 to 2, The heat absorbing member includes 300 parts by mass or more of the aluminum hydroxide based on 100 parts by mass of the resin.

2. The battery module according to claim 1, The heat absorbing member is arranged so that the heat absorption amount Qs per unit area relative to the surface of the single cell is 50 J / cm 2 above.

3. The battery module according to claim 1 or 2, The resin is silicone rubber.

4. A heat absorbing member used between a housing and a single cell and / or between a plurality of single cells, comprising a resin and a filler, The resin is rubber or elastomer, The filler contains at least aluminum hydroxide, The heat absorption capacity Q of the heat absorption component from 150°C to 350°C is 500 J / cm 3 and the thermal conductivity λ of the heat absorbing component is greater than 0.8 W / mK. The product of the thermal conductivity λ and the heat absorption Q, λ×Q, is 1000W·J / mK·cm 3 above, The aluminum hydroxide contains small-particle aluminum hydroxide with an average particle size of less than 2 μm and large-particle aluminum hydroxide with an average particle size of more than 2 μm. The amount of the small-particle aluminum hydroxide relative to the large-particle aluminum hydroxide, that is, the small-particle aluminum hydroxide / large-particle aluminum hydroxide is 0.1 to 2, The heat absorbing member includes 300 parts by mass or more of the aluminum hydroxide based on 100 parts by mass of the resin.

5. An endothermic composition for forming the endothermic component according to claim 4, comprising: A mixed liquid polymer composition consisting of a main agent and a curing agent; and A filler comprising at least aluminum hydroxide.

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