Composite material, battery assembly, electric device and energy storage system

Abstract

The embodiments of the present disclosure provide a composite material, a battery assembly, an electric device and an energy storage system. The composite material has both heat absorption and heat insulation functions, and can effectively improve the thermal safety performance of a battery assembly.

Description

Composite materials, battery components, electrical equipment and energy storage systems

[0001] This disclosure claims priority to the Chinese patent application filed with the Patent Office of China on December 29, 2023, with application number 202311871040.9 and application name “Composite materials, battery components, electrical equipment and energy storage systems,” the entire contents of which are incorporated by reference into this disclosure. Technical Field

[0002] The present disclosure relates to the technical field of composite materials, and in particular to composite materials, battery components, electrical equipment and energy storage systems. Background Art

[0003] With the advancement of science and technology, the application of secondary batteries is becoming increasingly widespread, especially in electrical equipment and energy storage systems with high energy consumption requirements. These electrical equipment and energy storage systems are generally equipped with battery modules composed of multiple single cells. However, under extreme operating conditions, if a single cell experiences thermal runaway, the heat can easily spread throughout the battery module, causing thermal runaway of the entire battery module, resulting in safety accidents such as fire and explosion.

[0004] To suppress the spread of heat generated by individual cells in battery modules, the industry has attempted to place organic porous materials around the cells, using their superior thermal insulation properties to slow the spread of heat. However, organic porous materials have no cooling effect and offer limited benefits in improving the thermal safety of battery modules.

[0005] Summary of the Invention

[0006] In view of this, embodiments of the present disclosure provide a composite material, a battery assembly, an electrical device, and an energy storage system. The composite material has both heat absorption and heat insulation functions, which can effectively improve the thermal safety performance of the battery assembly.

[0007] A first aspect of an embodiment of the present disclosure provides a composite material, comprising a thermal insulation matrix and a functional material and a plurality of heat-absorbing particles dispersed in the thermal insulation matrix; the heat-absorbing particles are selected from at least one of sodium pyrophosphate decahydrate, potassium aluminum sulfate dodecahydrate, ammonium aluminum sulfate dodecahydrate, barium hydroxide octahydrate, magnesium chloride hexahydrate, and aluminum sulfate 18hydrate; the functional material comprises at least one of silicon carbide, carbon black, and aluminum oxide.

[0008] When the ambient temperature rises, the heat-absorbing particles dispersed within the insulating matrix undergo a phase change, absorbing heat from the environment and reducing the hotspot and surrounding ambient temperature. Simultaneously, the functional material accelerates heat conduction within the composite material within this temperature range, allowing the heat-absorbing material elsewhere in the composite material (besides the hotspot and its vicinity) to also rapidly absorb heat. The insulating matrix, on the other hand, can exert its inherent insulating properties. Therefore, through the synergistic effect of these three substances, the composite material achieves both excellent heat absorption and insulation. As the ambient temperature rises further, the heat-absorbing particles partially or completely decompose into gas due to the absorption of heat, increasing the porosity of the insulating matrix and thus its insulating effect. Furthermore, the functional material now prioritizes its infrared shading properties, effectively reducing radiant heat transfer, allowing the composite material to focus on its insulating properties.

[0009] Optionally, the D90 of the heat-absorbing particles is 10 μm-50 μm.

[0010] Optionally, the total mass proportion of the plurality of heat-absorbing particles in the composite material is 50%-95%. Further, the total mass proportion of the plurality of heat-absorbing particles in the composite material is 70%-95%.

[0011] Optionally, the heat insulating matrix accounts for 5% to 45% by mass of the composite material. Further, the heat insulating matrix accounts for 10% to 20% by mass of the composite material.

[0012] Optionally, the material of the heat-insulating matrix includes at least one of epoxy resin, polyurethane, acrylate, polyimide, silicone rubber and EPDM rubber.

[0013] Optionally, the total mass proportion of the functional materials in the composite material is 0.5%-20%. Further, the total mass proportion of the functional materials in the composite material is 1%-10%.

[0014] Optionally, the size of the functional material is 1 μm-20 μm; further, the size of the functional material is 2 μm-8 μm.

[0015] Optionally, the composite material has an endothermic peak temperature of 70°C-160°C.

[0016] Optionally, when the ambient temperature is greater than or equal to 25° C. and less than the phase change starting temperature of the composite material, the thermal conductivity of the composite material is 0.1 W / (m·K)-2 W / (m·K).

[0017] When the ambient temperature is in the range of greater than or equal to the phase change starting temperature of the composite material to less than 160° C., the thermal conductivity of the composite material is 0.02 W / (m·K)-2 W / (m·K).

[0018] When the ambient temperature is ≥160° C., the thermal conductivity of the composite material is 0.02 W / (m·K)-0.08 W / (m·K).

[0019] Optionally, when the ambient temperature is in the range of greater than or equal to the phase transition starting temperature of the composite material to less than 160° C., the composite material has an endothermic enthalpy of 500 kJ / kg to 2000 kJ / kg. When the ambient temperature is 160° C. to 500° C., the composite material has an endothermic enthalpy of 100 kJ / kg to 500 kJ / kg.

[0020] Optionally, when the ambient temperature is ≥160° C., at least 60 wt. % of the heat-absorbing particles in the composite material are decomposed by heat.

[0021] Optionally, when the ambient temperature is greater than or equal to the phase change starting temperature of the composite material, holes are formed in the thermal insulation matrix.

[0022] Optionally, the density of the composite material is 1000 kg / m 3 -2500kg / m 3 .

[0023] Optionally, the composite material has a thickness of 0.1 mm to 10 mm.

[0024] A second aspect of the embodiments of the present disclosure provides a battery assembly, comprising a plurality of single cells and the composite material provided by the first aspect of the embodiments of the present disclosure, wherein the composite material is arranged between adjacent single cells.

[0025] Since the composite material is arranged between adjacent single cells, when thermal runaway occurs in one or several single cells in the above-mentioned battery assembly, the composite material can effectively absorb and block the heat generated by the single cells, thereby effectively inhibiting the spread of heat in the battery assembly, thereby reducing the risk of thermal runaway of the battery assembly and improving the thermal safety performance of the battery assembly.

[0026] The third aspect of the embodiment of the present disclosure provides an electric device, comprising the battery assembly provided by the second aspect of the embodiment of the present disclosure. Due to the battery assembly provided by the embodiment of the present disclosure, the electric device has a good market prospect.

[0027] A fourth aspect of the present disclosure provides an energy storage system, including the battery assembly provided by the second aspect of the present disclosure. Due to the battery assembly provided by the present disclosure, the energy storage system has high thermal safety performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] FIG1 is a simplified structural diagram of a battery assembly provided in one embodiment of the present disclosure. DETAILED DESCRIPTION

[0029] Battery packs, battery modules and other battery components contain a large number of single cells, which are often installed in new energy vehicles, energy storage devices and other equipment. As the number of single cells increases, the probability and severity of thermal runaway of battery components under abuse conditions (mechanical abuse, electrical abuse) also increase. Therefore, the market attaches great importance to the thermal safety performance of battery components. Providing thermal insulation materials around single cells is a common method used by the industry to improve the thermal safety performance of battery components. The thermal insulation materials in the existing technology are generally organic porous materials. Although such materials have a high thermal insulation coefficient, they cannot effectively absorb heat, resulting in limited heat dissipation effect of the battery components. The risk of heat spread and thermal runaway is still high.

[0030] To solve the above technical problems, the present disclosure provides a composite material comprising an insulating matrix and a functional material and a plurality of heat-absorbing particles dispersed in the insulating matrix; the heat-absorbing particles are selected from at least one of sodium pyrophosphate decahydrate, potassium aluminum sulfate dodecahydrate, ammonium aluminum sulfate dodecahydrate, magnesium chloride hexahydrate, barium hydroxide octahydrate, and aluminum sulfate 18hydrate. The heat-absorbing particles of each of the above materials have stable properties, and the heat-absorbing particles are dispersed in the insulating matrix and encapsulated by it. Therefore, the composite material can be stably stored at the operating temperature of the battery (generally below 70°C) without undergoing phase change. Therefore, during the long cycle or long storage of the battery, the composite material will not leak heat-absorbing particles or phase separation of the composite material, and the structure is stable. When the temperature rises, the heat-absorbing particles will decompose and produce gas after absorbing heat, escaping from the composite material and forming open pores in the insulating matrix, and / or remaining in the composite material to form bubbles (i.e., forming closed pores in the insulating matrix). The above is equivalent to creating pores in the insulating matrix, which can further improve the thermal insulation performance of the insulating matrix. In some embodiments of the present disclosure, the heat-absorbing particles are selected from at least one of potassium aluminum sulfate dodecahydrate, ammonium aluminum sulfate dodecahydrate, barium hydroxide octahydrate, and aluminum sulfate 18hydrate. Thus, at the same mass, the composite material has a suitable heat-absorbing temperature range and a higher heat-absorbing capacity.

[0031] The functional material includes at least one of silicon carbide, carbon black, and aluminum oxide. The embodiment of the present disclosure does not limit the form of the functional material, which can be in a granular or fibrous form.

[0032] The composite material has both heat absorption and heat insulation effects, and the thermal conductivity coefficient is different in different temperature ranges. The composite material has different heat insulation and heat absorption performance in different temperature ranges. Specifically: when the ambient temperature rises but is still lower than the phase change starting temperature of the composite material, the composite material can use its own specific heat capacity to absorb heat. It can be understood that the battery generates less heat at this time, and the composite material can play a certain heat insulation and heat absorption effect. When the ambient temperature rises (for the convenience of description, this temperature range is referred to as the "heat absorption temperature range" below), the heat absorption particles dispersed in the thermal insulation matrix can undergo a phase change and absorb heat from the environment, reducing the hot spot and the surrounding ambient temperature. The greater the thermal enthalpy value of the composite material in the heat absorption temperature range, the more conducive it is to heat absorption; at the same time, based on the physical properties of silicon carbide, carbon black and aluminum oxide, the functional material has a high thermal conductivity in the heat absorption temperature range, which can quickly transfer heat from the hot spot to other locations in the composite material, so that the heat can be quickly absorbed by the heat absorption particles at other locations, promoting cooling. It is understandable that in the endothermic temperature range, when the thermal conductivity of the composite material is large, it is beneficial to the heat conduction inside the composite material, and based on the material properties, in the endothermic temperature range, the thermal conductivity of the composite material will continue to decrease with the increase of temperature; and the thermal insulation matrix can play its inherent thermal insulation properties. Therefore, the synergistic effect of the above three substances can give the composite material better heat absorption and thermal insulation effects in the endothermic temperature range. When the ambient temperature is further increased (for the convenience of description, this temperature range is referred to as the "insulation temperature range" below), the above-mentioned endothermic particles partially or completely decompose into gas due to heat absorption, which can increase the porosity of the insulation matrix (including open and closed pores), thereby improving the thermal insulation effect of the insulation matrix; and the functional material at this time also changes to focus on playing the role of infrared sunscreen, effectively reducing the radiation heat transfer in the composite material, thereby further improving the thermal insulation effect of the composite material; it is understandable that in the insulation temperature range, the smaller the thermal conductivity of the composite material, the more conducive to thermal insulation. Therefore, when the above-mentioned composite material is applied to the battery assembly, the thermal safety performance of the battery assembly can be effectively improved.

[0033] Furthermore, the insulating matrix also supports the heat-absorbing particles and functional materials, effectively improving the composite material's formability. Consequently, the composite material can be processed into any desired shape, such as sheets, cylinders, and prisms, with highly controllable thickness, embracing a wide range of applications.

[0034] In the embodiments of the present disclosure, the ambient temperature refers to the temperature of the environment in which the composite material is located. For example, when the composite material is used in a battery assembly, the ambient temperature refers to the temperature at the location in the battery assembly where the composite material is located.

[0035] In some embodiments of the present disclosure, the D90 of the heat-absorbing particles is 10μm-50μm. In some specific embodiments, the D90 of the heat-absorbing particles is 20μm-40μm. Controlling the particle size of the heat-absorbing particles within the above range is not only beneficial to the dispersion of the heat-absorbing particles in the composite material and improving the uniformity of the composite material; it is also beneficial to the coordination of the heat-absorbing particles and the functional materials, and constructing a more complete network structure in the thermal insulation matrix, so that the composite material has a more complete heat-conducting-heat-absorbing network within the heat-absorbing temperature range, and can improve the thermal insulation effect of the composite material within the heat-insulating temperature range. For example, the D90 of the heat-absorbing particles can be, but is not limited to, 10μm, 15μm, 20μm, 22μm, 25μm, 28μm, 30μm, 32μm, 35μm, 38μm, 40μm, 45μm, 50μm, etc.

[0036] In the embodiments of the present disclosure, the D90 of the endothermic particles was measured using a scanning electron microscope (SEM). Specifically, a cross-section of the composite material was observed under the SEM, and the particle size corresponding to the cumulative volume distribution percentage of the endothermic particles in the composite material reaching 90% was calculated as the D90 of the endothermic particles.

[0037] In some embodiments of the present disclosure, the total mass percentage of the multiple heat-absorbing particles in the composite material is 50%-95%. In some specific embodiments, the total mass percentage of the multiple heat-absorbing particles in the composite material is 70%-95%. Controlling the mass percentage of the heat-absorbing particles in the composite material within the above range can enable the composite material to achieve a higher thermal enthalpy value within the heat-absorbing temperature range and achieve a better heat absorption effect. When the heat-absorbing particles undergo an endothermic phase change and decompose to produce gas, the porosity or bubble content of the insulating matrix can be significantly increased, thereby effectively improving the thermal insulation performance of the composite material within the heat-insulating temperature range. For example, the mass percentage of the multiple heat-absorbing particles in the composite material can be, but is not limited to, 50.0%, 55.0%, 60.0%, 65.0%, 70.0%, 72.5%, 75.0%, 77.5%, 80.0%, 82.5%, 85.0%, 87.5%, 90.0%, 92.5%, 95.0%, etc.

[0038] In some embodiments of the present disclosure, the endothermic temperature range is from an ambient temperature greater than or equal to the phase transition starting temperature of the composite material to less than 160°C, and the endothermic enthalpy of the composite material in the endothermic temperature range is 500kJ / kg-2000kJ / kg; the adiabatic temperature range is from an ambient temperature greater than or equal to 160°C, and the endothermic enthalpy of the composite material in the adiabatic temperature range is 100kJ / kg-500kJ / kg. For example, the endothermic enthalpy of the composite material in the endothermic temperature range may be, but is not limited to, 500kJ / kg, 800kJ / kg, 1000kJ / kg, 1100kJ / kg, 1200kJ / kg, 1300kJ / kg, 1500kJ / kg, 1600kJ / kg, 1800kJ / kg, 2000kJ / kg, etc. For example, the composite material's endothermic enthalpy within the heat-insulating temperature range may be, but is not limited to, 100 kJ / kg, 200 kJ / kg, 300 kJ / kg, 400 kJ / kg, 500 kJ / kg, etc. In some specific embodiments, the composite material's endothermic enthalpy within the heat-absorbing temperature range is 1000 kJ / kg-1500 kJ / kg. Thus, when the composite material is applied to a battery module, it can effectively absorb the heat generated by the individual cells when abnormal heat generation occurs. Furthermore, the composite material is easier to manufacture.

[0039] It should be noted that in the embodiments of the present disclosure, the phase change starting temperature of the composite material is measured using a differential scanning calorimeter (DSC). Specifically, the sample to be tested is placed in an alumina crucible, the equipment heating rate is 10°C / min, the temperature rise range is 25°C-500°C, the atmosphere is nitrogen, and the temperature corresponding to the starting point of the endothermic peak of the measured DSC curve is the above-mentioned "phase change starting temperature of the composite material". Exemplarily, the phase change starting temperature of the composite material can be 70°C, 72°C, 75°C, 78°C, 80°C, 82°C, 85°C, etc.

[0040] In some embodiments of the present disclosure, the sum of the mass proportions of functional materials in the composite material is 0.5%-20%. In some specific embodiments, the sum of the mass proportions of functional materials in the composite material is 1%-10%. In this way, it is beneficial to take into account the thermal conductivity and endothermic enthalpy of the composite material in the endothermic temperature range, thereby accelerating the heat exchange of the composite material in the endothermic temperature range and promoting the endothermic particles at different positions of the composite material to exert their effectiveness; in addition, it can reduce the radiative heat transfer of the composite material in the insulation temperature range, thereby ensuring that the composite material has a better insulation effect in the insulation temperature range. For example, the sum of the mass proportions of functional materials in the composite material can be, but is not limited to, 0.5%, 1.0%, 2.0%, 4.0%, 5.0%, 6.0%, 7.0%, 8.0%, 9.0%, 10.0%, 12.0%, 14.0%, 16.0%, 18.0%, and 20.0%.

[0041] In some embodiments of the present disclosure, when the ambient temperature is greater than or equal to 25°C and less than the phase transition starting temperature of the composite material (when the composite material is greater than or equal to 25°C and less than the endothermic temperature), the thermal conductivity of the composite material is 0.1W / (m·K)-2W / (m·K). For example, when the ambient temperature is greater than or equal to 25°C and less than the phase transition starting temperature of the composite material, the thermal conductivity of the composite material may be, but is not limited to, 0.1W / (m·K), 0.2W / (m·K), 0.5W / (m·K), 0.8W / (m·K), 1.0W / (m·K), 1.2W / (m·K), 1.5W / (m·K), 1.8W / (m·K), or 2.0W / (m·K).

[0042] When the ambient temperature is within the range of greater than or equal to the composite material's phase transition starting temperature to less than 160°C (the composite material's endothermic temperature range), the composite material's thermal conductivity is 0.02W / (m·K)-2.0W / (m·K). When the ambient temperature is greater than or equal to 160°C (the composite material's insulation range), the composite material's thermal conductivity is 0.02W / (m·K)-0.08W / (m·K). It should also be noted that the composite material's thermal conductivity decreases as the temperature rises within the endothermic temperature range until the temperature rises further to the insulation temperature range. Exemplarily, the thermal conductivity of the composite material in the endothermic temperature range may be, but is not limited to, 0.02 W / (m·K), 0.05 W / (m·K), 0.08 W / (m·K), 0.10 W / (m·K), 0.20 W / (m·K), 0.50 W / (m·K), 0.80 W / (m·K), 1.00 W / (m·K), 1.20 W / (m·K), 1.40 W / (m·K), 1.60 W / (m·K), 1.80 W / (m·K), 2.0 W / (m·K), etc. For example, the thermal conductivity of the composite material within the insulation temperature range may be, but is not limited to, 0.02 W / (m·K), 0.03 W / (m·K), 0.04 W / (m·K), 0.05 W / (m·K), 0.06 W / (m·K), 0.08 W / (m·K), etc. In the embodiments of the present disclosure, with reference to ASTM C518, a thermal conductivity meter for thermal insulation materials is used to characterize the thermal conductivity of the composite material.

[0043] In some embodiments of the present disclosure, the size of the functional material is 1μm-20μm. When the functional material is granular, the above size refers to the D90 of the functional material particles; when the functional material is fibrous, the above size refers to the diameter of the functional fiber material. For example, the size of the functional material can be 1μm, 2μm, 5μm, 8μm, 10μm, 12μm, 15μm, 18μm, 20μm, etc. In some specific embodiments, the size of the functional material is 2μm-8μm. In this way, it is beneficial to disperse the functional material in the thermal insulation matrix, improve the uniformity of the thermal conductivity coefficient inside the composite material, and also facilitate the construction of a thermal conductive network inside the composite material, thereby further improving the thermal protection performance of the composite material. In addition, the functional material under this size has good anti-infrared radiation effect in the high temperature section, thereby improving the thermal insulation ability of the material at high temperature. The size of the functional material can be measured using a scanning electron microscope.

[0044] In some embodiments of the present disclosure, the mass proportion of the thermal insulation matrix in the composite material is 5%-45%. In some specific embodiments, the mass proportion of the thermal insulation matrix in the composite material is 10%-20%. The appropriate mass proportion of the thermal insulation matrix is ​​conducive to the molding of the composite material, and gives the composite material certain mechanical properties. It can also better wrap the heat-absorbing particles, preventing the leakage of heat-absorbing particles or the phase separation of the composite material, which affects the performance of the composite material. At the same time, it can enable the composite material to play a good heat-insulating role in both the heat-absorbing temperature range and the heat-insulating temperature range, and will not squeeze out the proportion of other components, which is conducive to improving the overall performance of the composite material. For example, the mass proportion of the thermal insulation matrix in the composite material can be, but is not limited to, 5%, 8%, 10%, 12%, 15%, 18%, 20%, 22%, 25%, 28%, 30%, 32%, 35%, 38%, 40%, 42%, 45%, etc.

[0045] In some embodiments of the present disclosure, the material of the above-mentioned thermal insulation substrate includes but is not limited to at least one of epoxy resin, polyurethane, acrylate, polyimide, silicone rubber and EPDM rubber. The thermal conductivity of the above-mentioned materials is low, that is, they have good thermal insulation performance, and have certain toughness and strength, which is beneficial to the mechanical properties of the composite material. In some specific embodiments, the material of the thermal insulation matrix is ​​selected from at least one of epoxy resin, polyurethane and silicone rubber. In this way, the thermal insulation matrix has better temperature resistance and mechanical properties, which can ensure that the thermal insulation matrix has good structural retention in the thermal insulation temperature range, thereby ensuring the realization of thermal insulation performance.

[0046] In some embodiments of the present disclosure, the composite material includes the following components in parts by weight: 5-45 parts of a thermally insulating matrix, 0.5-20 parts of a functional material, and 50-95 parts of endothermic particles. With the above components combined, the composite material exhibits a peak endothermic temperature of 70°C-160°C; that is, the peak temperature of the endothermic peak exhibited by the composite material in DSC is 70°C-160°C. For example, the composite material's peak endothermic temperature can be 70°C, 72°C, 75°C, 78°C, 80°C, 82°C, 85°C, etc. It is understood that, when other parameters are similar, the closer the composite material's peak endothermic temperature is to 70°C, the better it is at controlling heat spread (for example, controlling heat spread within the battery assembly), thereby providing better protection. It should be noted that due to different material choices for the endothermic particles and differences in the composite material's ratio, the composite material's peak endothermic temperature may be close to or nearly coincide with the phase transition onset temperature; this does not affect the composite material's effectiveness.

[0047] In some specific embodiments, the composite material includes the following components in the following weight proportions: 10-20 parts of a thermally insulating matrix, 1-10 parts of a functional material, and 70-90 parts of heat-absorbing particles. This composite material exhibits both good formability and mechanical properties, exhibits good heat absorption and cooling effects in the endothermic temperature range, and exhibits good thermal insulation properties in the heat-insulating temperature range. At this time, when the ambient temperature is greater than or equal to 25°C and less than the phase change starting temperature of the composite material, the thermal conductivity of the composite material is 0.1W / (m·K)-2W / (m·K); when the ambient temperature is greater than or equal to the phase change starting temperature of the composite material and less than 160°C, the thermal conductivity of the composite material is 0.02W / (m·K)-2.0W / (m·K); when the ambient temperature is ≥160°C, the thermal conductivity of the composite material is 0.02W / (m·K)-0.08W / (m·K); when the ambient temperature is greater than or equal to the phase change starting temperature of the composite material and less than 160°C, the endothermic enthalpy of the composite material is 500kJ / kg-2000kJ / kg; when the ambient temperature is 160°C-500°C, the endothermic enthalpy of the composite material is 100kJ / kg-500kJ / kg.

[0048] In the present disclosure, when measuring the weight ratio of each component in the composite material, the composite material can be weighed first, then the material is crushed, dissolved in deionized water, filtered, the crystallized hydrated salt material is soluble in water, the weight of the insoluble matter is weighed, and the weight of the crystallized hydrated salt is subtracted from the total weight of the composite material to obtain the weight of the crystallized hydrated salt, thereby obtaining the mass of the crystallized hydrated salt and the weight ratio in the composite material. The above-mentioned insoluble matter is further subjected to thermogravimetric analysis (TGA) analysis to obtain the weight ratio of the thermal insulation matrix and the reinforcing material.

[0049] It can be understood that based on the material of the endothermic particles defined in the present disclosure, the endothermic particles absorb heat and undergo phase change and decompose into gas. In some embodiments of the present disclosure, at least 60 wt.% of the endothermic particles are thermally decomposed within the insulating temperature range. DSC can be used to characterize the mass percentage of the endothermic particles that are thermally decomposed. For example, 65 wt.%-80 wt.% of the endothermic particles are thermally decomposed, and the unreacted decomposed part can continue to endothermically decompose within the insulating temperature range, which is beneficial to heat exchange inside the composite material. In some specific embodiments, the insulating temperature range is ≥160°C, that is, when the ambient temperature is ≥160°C, at least 60 wt.% of the endothermic particles in the composite material are thermally decomposed. In some embodiments of the present disclosure, when the ambient temperature is ≥160°C, at least 60 wt.% of any endothermic particle is thermally decomposed.

[0050] It can be understood that, as mentioned above, the heat-absorbing particles will generate gas after thermal decomposition to form open and / or closed pores in the thermal insulation matrix. In some embodiments of the present disclosure, when the ambient temperature is greater than or equal to the phase change starting temperature of the composite material, pores are formed in the thermal insulation matrix; when the ambient temperature is ≥160°C, the porosity of the thermal insulation matrix is ​​further improved, reaching 80% or more. Of course, in some specific embodiments, the thermal insulation matrix itself has a porous structure (the pore structure exists before the heat-absorbing particles are thermally decomposed), that is, the thermal insulation matrix is ​​a porous material.

[0051] In some embodiments of the present disclosure, the density of the composite material is 1000 kg / m 3 -2500kg / m 3 In some embodiments, the density of the composite material is 1300 kg / m 3 -2000kg / m 3 It should be noted that the above density refers to the density of the heat-absorbing particles in the composite material when they are not thermally decomposed. Controlling the density of the composite material within the above range can make the composite material have better heat insulation, heat absorption and compression resistance. When it is applied to the battery assembly, it can ensure that the energy density of the battery assembly is high. For example, the density of the composite material can be 1000kg / m 3 , 1200kg / m 3 、1500kg / m 3 、1800kg / m 3 , 2000kg / m 3 , 2200kg / m 3 , 2400kg / m 3 , 2500kg / m 3 wait.

[0052] In some embodiments of the present disclosure, the thickness of the composite material is within the range of 0.1 mm to 10 mm. Controlling the thickness of the composite material within this range not only provides good heat absorption and insulation effects, but also helps improve space utilization within the battery assembly. For example, the thickness of the composite material can be 0.1 mm, 0.5 mm, 1.0 mm, 2.0 mm, 5.0 mm, 8.0 mm, 10.0 mm, etc.

[0053] The present disclosure also provides a battery assembly comprising a plurality of single cells and the aforementioned composite material provided in the present disclosure, wherein the composite material is disposed between adjacent single cells. Since the composite material is disposed between adjacent single cells, when thermal runaway occurs in one or more single cells in the battery assembly, the composite material can effectively absorb and block the heat generated by the single cells, thereby effectively inhibiting the spread of heat in the battery assembly, thereby reducing the risk of thermal runaway in the battery assembly and improving the thermal safety performance of the battery assembly. For a schematic structural diagram of the battery assembly provided in one embodiment of the present disclosure, please refer to FIG1 . The number, relative position, size, and shape of the single cells and composite material in FIG1 are all illustrative.

[0054] In the embodiments of the present disclosure, the battery assembly includes, but is not limited to, a battery pack or a battery module. The single battery cell may be, but is not limited to, a lithium-ion battery, a sodium-ion battery, an aluminum-ion battery, or the like. The single battery cell may be of any shape, such as cylindrical, square, irregular, or prismatic.

[0055] In some embodiments of the present disclosure, the composite material is disposed between any two adjacent single batteries.

[0056] The present disclosure also provides an electric device including the battery assembly provided in the present disclosure. Due to the battery assembly provided in the present disclosure, the electric device has a good market prospect.

[0057] In some embodiments of the present disclosure, the above-mentioned electrical equipment includes but is not limited to automobiles, consumer electronic products, electric bicycles, etc.

[0058] The present disclosure also provides an energy storage system including the battery assembly provided in the present disclosure. Due to the use of the battery assembly provided in the present disclosure, the energy storage system has high thermal safety performance.

[0059] The technical solution of the present disclosure is further illustrated below with multiple embodiments.

[0060] Example 1

[0061] A composite material includes heat-absorbing particles (specifically, a eutectic of ammonium aluminum sulfate dodecahydrate and sodium sulfate decahydrate with a D90 of 30 μm) in a mass ratio of 80:15:5, a heat-insulating matrix (specifically, silicone rubber), and a functional material (specifically, silicon carbide fiber with a diameter of 3-6 μm).

[0062] Example 2

[0063] A composite material comprises heat-absorbing particles (specifically barium hydroxide octahydrate with a D90 particle size of 30 μm) in a mass ratio of 85:10:5, a heat-insulating matrix (specifically epoxy resin), and a functional material (specifically silicon carbide particles with a particle size of 3-6 μm).

[0064] Example 3-16

[0065] For ease of reading, various parameters of the composite materials of Examples 3 to 16 and Examples 1 and 2 are summarized in Table 1.

[0066] Table 1

[0067] In order to highlight the beneficial effects of the embodiments of the present disclosure, the following comparative examples are provided.

[0068] Comparative Example 1

[0069] A composite material comprises crystalline hydrated salt particles, an epoxy resin matrix, and alumina powder (D90 particle size: 5 μm). The crystalline hydrated salt is disodium hydrogen phosphate dodecahydrate (D90 particle size: 30 μm), and the epoxy resin matrix has a non-porous structure. In the composite material, the mass ratio of the crystalline hydrated salt particles, epoxy resin matrix, and alumina powder is 70:20:10.

[0070] Performance Testing

[0071] (1) Thermal conductivity of materials: The thermal conductivity of composite materials was tested with reference to ASTM C518 Standard test method ofr steady-state thermal transmission properties by means of the heat flow meter apparatus.

[0072] (2) The thermal enthalpy of the composite material was tested using a differential scanning calorimeter (DSC). The sample to be tested was placed in an alumina crucible, the equipment heating rate was 10°C / min, the temperature rise range was 25°C to 500°C, and the atmosphere was nitrogen.

[0073] (3) The density of the composite material shall be measured by the hydrostatic weighing method in accordance with GB / T 4472-2011 Chemical products - Determination of density and relative density.

[0074] (4) Referring to GB / T 2423.102 Environmental testing for electrical and electronic products Part 2: Test methods: Temperature (low temperature, high temperature) / low pressure / vibration (sinusoidal) combined, the samples were placed in an alternating temperature environment of -40°C to 70°C. The transition time between the two extreme temperatures was within 3 minutes. The tested samples were kept in each extreme temperature environment for 30 minutes, with one cycle lasting 1 hour, 1000 cycles, and a total of 1000 hours. After the cycles, the composite material samples were observed for leakage and phase separation.

[0075] (5) Assemble the composite material and battery cells into a battery pack for testing. Refer to the wet heat cycle requirements in GB 38031-2020 Safety Requirements for Power Batteries for Electric Vehicles. The battery pack is subjected to a maximum temperature of 70°C and cycles five times. After the test is complete, disassemble and observe the leakage of the composite material.

[0076] Table 2

[0077] From the data in Tables 1 and 2, it can be seen that the composite material provided by the embodiments of the present disclosure exhibits good heat absorption and thermal insulation performance in the heat absorption temperature range, and still has good thermal insulation performance in the thermal insulation temperature range. In addition, the performance of the composite material is stable, and leakage of the heat absorption material and phase separation of the composite material will not occur.

[0078] Comparing the data between the examples, it can be found (Examples 1, 3, and 4) that when the material of the heat-absorbing particles is the material further suggested by the present disclosure (Example 1), the composite material has a relatively high endothermic enthalpy value in the endothermic temperature range, better heat absorption capacity, lower phase change starting temperature and endothermic peak temperature of the composite material, and better comprehensive protective performance. Comparing the data of Example 2 and Example 6, it can be found that when the particle size of the heat-absorbing particles is within the range suggested by the present disclosure (Example 2), the composite material has a better endothermic effect in the endothermic temperature range. Comparing the data of Examples 8-12, it can be found that when the mass proportion of each material is within the range suggested by the present disclosure, the composite material has better endothermic performance in the endothermic temperature range and better thermal insulation effect in the thermal insulation temperature range. Comparing the data of Example 2 and Example 15, it can be found that when the particle size of the functional material is within the range suggested by the present disclosure (Examples 8-9 and 11), when the ambient temperature is ≥160°C, the thermal conductivity of the composite material is relatively low, the thermal insulation performance is better, and it is more conducive to the performance of the protective performance of the composite material.

[0079] The above is an exemplary embodiment of the present disclosure. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made thereto without departing from the principles of the present disclosure. These improvements and modifications are also considered to be within the scope of protection of the present disclosure.

Claims

1. A composite material, characterized in that, It includes a heat-insulating matrix, functional materials dispersed in the heat-insulating matrix, and a plurality of heat-absorbing particles; The heat-absorbing particles are selected from at least one of sodium pyrophosphate decahydrate, potassium alum dodecahydrate, ammonium alum dodecahydrate, magnesium chloride hexahydrate, barium hydroxide octahydrate, and aluminum sulfate octadecahydrate; The functional materials include at least one of silicon carbide, carbon black, and aluminum oxide.

2. The composite material according to claim 1, wherein The D90 of the heat-absorbing particles is 10 μm - 50 μm.

3. The composite material according to claim 1 or 2, characterized in that, The sum of the mass ratios of the plurality of heat-absorbing particles in the composite material is 50% - 95%.

4. The composite material according to claim 2, wherein The sum of the mass ratios of the plurality of heat-absorbing particles in the composite material is 70% - 95%.

5. The composite material according to any one of claims 1-4, characterized in that, The mass ratio of the heat-insulating matrix in the composite material is 5% - 45%.

6. The composite material according to claim 5, wherein, The mass ratio of the heat-insulating matrix in the composite material is 10% - 20%.

7. The composite material according to any one of claims 1-6, characterized in that, The material of the heat-insulating matrix includes at least one of epoxy resin, polyurethane, acrylate, polyimide, silicone rubber, and ethylene propylene diene monomer rubber.

8. The composite material according to any one of claims 1-7, characterized in that, The sum of the mass ratios of the functional materials in the composite material is 0.5% - 20%.

9. The composite material according to claim 8, characterized in that, The sum of the mass ratios of the functional materials in the composite material is 1% - 10%.

10. The composite material according to any one of claims 1-9, characterized in that, The size of the functional materials is 1 μm - 20 μm; optionally, the size of the functional materials is 2 μm - 8 μm.

11. The composite material according to any one of claims 1-10, characterized in that, The peak temperature of the heat absorption peak of the composite material is 70°C - 160°C.

12. The composite material according to any one of claims 1 - 11, wherein When the ambient temperature is in the range of greater than or equal to 25°C to less than the phase change start temperature of the composite material, the thermal conductivity of the composite material is 0.1 W / (m·K) - 2 W / (m·K); When the ambient temperature is in the range of greater than or equal to the phase change start temperature of the composite material to less than 160°C, the thermal conductivity of the composite material is 0.02 W / (m·K) - 2 W / (m·K); When the ambient temperature is greater than or equal to 160°C, the thermal conductivity of the composite material is 0.02 W / (m·K) - 0.08 W / (m·K).

13. The composite material according to any one of claims 1-12, characterized in that, When the ambient temperature is in the range of greater than or equal to the phase change start temperature of the composite material to less than 160°C, the heat absorption enthalpy value of the composite material is 500 kJ / kg - 2000 kJ / kg; when the ambient temperature is 160°C - 500°C, the heat absorption enthalpy value of the composite material is 100 kJ / kg - 500 kJ / kg; optionally, when the ambient temperature is in the range of greater than or equal to the phase change start temperature of the composite material to less than 160°C, the heat absorption enthalpy value of the composite material is 1000 KJ / Kg - 1500 KJ / Kg.

14. The composite material according to any one of claims 1-13, characterized in that, When the ambient temperature ≥ 160°C, at least 60 wt.% of the heat-absorbing particles in the composite material are thermally decomposed.

15. The composite material according to any one of claims 1-14, characterized in that, When the ambient temperature is greater than or equal to the phase change start temperature of the composite material, holes are formed in the heat-insulating matrix.

16. The composite material according to any one of claims 1 to 15, characterized in that, The density of the composite material is 1000 kg / m 3 - 2500 kg / m 3 ; Optionally, the density of the composite material is 1300 kg / m 3 - 2000 kg / m 3 .

17. The composite material according to any one of claims 1-16, characterized in that, The thickness of the composite material is 0.1 mm - 10 mm.

18. A battery assembly, characterized in that, The battery module includes a plurality of single cells and the composite material according to any one of claims 1 - 16, and the composite material is disposed between adjacent single cells.

19. An electrical device, characterized in that, The electrical device includes the battery assembly as described in claim 18.

20. A energy storage system, characterized in that, The energy storage system includes the battery assembly as described in claim 18.

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