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

Abstract

The embodiment of the invention provides a composite material, a battery assembly, electric equipment and an energy storage system. The composite material has the functions of heat absorption and heat insulation at the same time, and can effectively improve the thermal safety performance of the battery assembly.

Description

Technical Field

[0001] The present application relates to the technical field of composite materials, and particularly to composite materials, battery modules, electrical equipment, and energy storage systems. Background Art

[0002] With the development of science and technology, secondary batteries are applied in more and more fields, especially in electrical equipment and energy storage systems with high energy consumption requirements. The above-mentioned electrical equipment / energy storage systems generally carry a battery module composed of multiple single cells. However, under extreme working conditions, if a single cell undergoes thermal runaway, heat is very likely to spread in the battery module, resulting in thermal runaway of the entire battery module and causing safety accidents such as fire and explosion.

[0003] In order to suppress the heat spread caused by single cells in the battery module, the industry has tried to set organic porous materials around the single cells to delay heat diffusion with their good heat insulation performance. However, the organic porous materials have no cooling effect, and the improvement of the thermal safety performance of the battery module is limited. Summary of the Invention

[0004] In view of this, the embodiments of the present application provide composite materials, battery modules, electrical equipment, and energy storage systems. The composite materials have both heat absorption and heat insulation functions, and can effectively improve the thermal safety performance of the battery module.

[0005] A first aspect of the embodiments of the present application provides a composite material, including a heat insulation matrix, functional materials, and a plurality of heat absorption particles dispersed in the heat insulation matrix; the heat absorption particles are selected from at least one of sodium pyrophosphate decahydrate, potassium alum dodecahydrate, ammonium alum dodecahydrate, barium hydroxide octahydrate magnesium chloride hexahydrate, and aluminum sulfate octadecahydrate;

[0006] The functional materials include at least one of silicon carbide, carbon black, and alumina.

[0007] When the ambient temperature rises, the above-mentioned heat absorption particles dispersed in the heat insulation matrix can undergo a phase change to absorb the heat in the environment, reduce the heat generation point and the ambient temperature around it; at the same time, the functional materials can accelerate the heat conduction inside the composite material within this temperature range, so that the heat absorption materials at other positions (except the heat generation point and its vicinity) in the composite material can also absorb heat quickly; and the heat insulation matrix can exert its inherent heat insulation property. Therefore, under the synergistic effect of the above three substances, the composite material can achieve good heat absorption and heat insulation effects at the same time. When the ambient temperature rises further, the above-mentioned heat absorption particles are partially or completely decomposed into gases due to heat absorption, which can increase the porosity of the heat insulation matrix, thereby improving the heat insulation effect of the heat insulation matrix; and at this time, the functional materials also focus on exerting their properties as infrared light blockers to effectively reduce radiative heat transfer, so the composite material focuses on exerting its heat insulation effect.

[0008] Optionally, the D90 of the endothermic particles is 10 μm - 50 μm.

[0009] Optionally, the sum of the mass percentages of the multiple endothermic particles in the composite material is 50% - 95%. Further, the sum of the mass percentages of the multiple endothermic particles in the composite material is 70% - 95%.

[0010] Optionally, the mass percentage of the heat-insulating matrix in the composite material is 5% - 45%. Further, the mass percentage of the heat-insulating matrix in the composite material is 10% - 20%.

[0011] Optionally, 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.

[0012] Optionally, the sum of the mass percentages of the functional materials in the composite material is 0.5% - 20%. Further, the sum of the mass percentages of the functional materials in the composite material is 1% - 10%.

[0013] Optionally, the size of the functional materials is 1 μm - 20 μm; further, the size of the functional materials is 2 μm - 8 μm.

[0014] Optionally, the endothermic peak temperature of the composite material is 70°C - 160°C.

[0015] Optionally, when the environmental temperature is greater than or equal to 25°C and 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);

[0016] When the environmental temperature is in the range of greater than or equal to the phase change start temperature of the composite material and less than 160°C, the thermal conductivity of the composite material is 0.02 W / (m·K) - 2 W / (m·K);

[0017] When the environmental temperature ≥ 160°C, the thermal conductivity of the composite material is 0.02 W / (m·K) - 0.08 W / (m·K).

[0018] Optionally, when the environmental temperature is in the range of greater than or equal to the phase change start temperature of the composite material and less than 160°C, the endothermic enthalpy value of the composite material is 500 kJ / kg - 2000 kJ / kg; when the environmental temperature is 160°C - 500°C, the endothermic enthalpy value of the composite material is 100 kJ / kg - 500 kJ / kg.

[0019] Optionally, when the environmental temperature ≥ 160°C, at least 60 wt.% of the endothermic particles in the composite material are thermally decomposed.

[0020] Optionally, 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 insulation matrix.

[0021] Optionally, the density of the composite material is 1000 kg / m 3 -2500 kg / m 3 .

[0022] Optionally, the thickness of the composite material is 0.1 mm - 10 mm.

[0023] A second aspect of the embodiments of the present application provides a battery assembly, including a plurality of single cells and the composite material provided in the first aspect of the embodiments of the present application, and the composite material is disposed between adjacent single cells.

[0024] Since the composite material is disposed between adjacent single cells, when one or several single cells in the above battery assembly undergo thermal runaway, the above 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, and further reducing the risk of thermal runaway of the battery assembly and improving the thermal safety performance of the battery assembly.

[0025] A third aspect of the embodiments of the present application provides an electrical device, including the battery assembly provided in the second aspect of the embodiments of the present application. Due to the battery assembly provided in the embodiments of the present application, the electrical device has a good market prospect.

[0026] A fourth aspect of the embodiments of the present application provides an energy storage system, including the battery assembly provided in the second aspect of the embodiments of the present application. Due to the battery assembly provided in the embodiments of the present application, the energy storage system has high thermal safety performance. Description of the Drawings

[0027] Figure 1 is a schematic structural diagram of a battery assembly provided in an embodiment of the present application. Detailed Embodiments

[0028] Battery assemblies such as battery packs and battery modules contain a large number of single cells, and these battery assemblies are often carried on devices such as new energy vehicles and energy storage devices. With the increase in the number of single cells, the probability and severity of thermal runaway of the battery assembly under abusive conditions (mechanical abuse, electrical abuse) also increase. Therefore, the market attaches great importance to the thermal safety performance of the battery assembly. Setting heat insulation materials around the single cells is a commonly used means in the industry to improve the thermal safety performance of the battery assembly. The heat insulation materials in the prior art are generally organic porous materials. Although such materials have a high heat insulation coefficient, they cannot effectively absorb heat, resulting in limited heat dissipation effect of the battery assembly, and the risk of heat spread and thermal runaway is still relatively high.

[0029] To solve the above technical problems, an embodiment of the present application provides a composite material, which includes a heat-insulating matrix, and functional materials and a plurality of heat-absorbing particles dispersed in the heat-insulating matrix; the heat-absorbing particles are selected from at least one of sodium pyrophosphate decahydrate, potassium alum, ammonium alum, magnesium chloride hexahydrate, barium hydroxide octahydrate, and aluminum sulfate octadecahydrate. The heat-absorbing particles of the above-mentioned various materials have stable properties, and the heat-absorbing particles are dispersed in the heat-insulating matrix and wrapped by it. Therefore, the composite material can be stably stored at the working temperature of the battery (generally below 70 °C) without undergoing a phase change. Therefore, during the long-term cycling or long-term storage of the battery, the composite material will not experience heat-absorbing particle leakage or phase separation of the composite material, and the structure is stable. When the temperature rises, the heat-absorbing particles will decompose and generate gas after absorbing heat, escape from the composite material, and form open pores in the heat-insulating matrix, and / or remain in the composite material to form bubbles (that is, closed pores are formed in the heat-insulating matrix). Above, it is equivalent to creating pores in the heat-insulating matrix, which can further improve the heat-insulating performance of the heat-insulating matrix. In some embodiments of the present application, the heat-absorbing particles are selected from at least one of potassium alum, ammonium alum, barium hydroxide octahydrate, and aluminum sulfate octadecahydrate. In this way, under the same mass, the composite material has a suitable heat-absorbing temperature range and higher heat-absorbing capacity.

[0030] The functional material includes at least one of silicon carbide, carbon black, and alumina. The embodiment of the present application does not limit the form of the functional material, which can be in the form of particles or in the form of fibers.

[0031] The above composite material has both heat absorption and heat insulation effects, and its thermal conductivity coefficient is different in different temperature ranges. The heat insulation and heat absorption performances of the composite material are different in different temperature ranges. Specifically, when the ambient temperature rises but remains lower than the phase change starting temperature of the composite material, the composite material can utilize its own specific heat capacity to absorb heat. Understandably, at this time, the heat generated by the battery is also less, 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 will be referred to as the "heat absorption temperature range" in the following text), the above-mentioned heat absorption particles dispersed in the heat insulation matrix can undergo a phase change to absorb the heat in the environment, reduce the heat generation point and the ambient temperature around it. The larger the 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 alumina, the functional material has a high thermal conductivity in the heat absorption temperature range, and can conduct the heat quickly from the heat generation point to other positions in the composite material, so that the heat can be quickly absorbed by the heat absorption particles at other positions, promoting cooling; Understandably, in the heat absorption temperature range, when the thermal conductivity coefficient of the composite material is larger, it is conducive to the heat conduction inside the composite material, and based on the material characteristics, in the heat absorption temperature range, the thermal conductivity coefficient of the composite material will continuously decrease with the increase of temperature; and the heat insulation matrix can play its inherent heat insulation property. Therefore, the synergistic effect of the above three substances can endow the composite material with better heat absorption and heat insulation effects in the heat absorption temperature range. When the ambient temperature further rises (for the convenience of description, this temperature range will be referred to as the "heat insulation temperature range" in the following text), the above-mentioned heat absorption particles are partially or completely decomposed into gases due to heat absorption, which can increase the porosity of the heat insulation matrix (including open pores and closed pores), thereby improving the heat insulation effect of the heat insulation matrix; and at this time, the functional material also changes to focus on playing the role of an infrared light-shielding agent, effectively reducing the radiative heat transfer in the composite material, thereby further improving the heat insulation effect of the composite material; Understandably, in the heat insulation temperature range, the smaller the thermal conductivity coefficient of the composite material, the more conducive it is to heat insulation. Therefore, when the above composite material is applied to the battery assembly, the thermal safety performance of the battery assembly can be effectively improved.

[0032] In addition, the heat insulation matrix also plays a role in carrying the heat absorption particles and the functional material, and can effectively improve the formability of the composite material. Therefore, the above composite material can be processed into any shape with strong thickness controllability according to the use requirements. For example, it can be in the shape of a sheet, a cylinder, or a prism, and has a wide range of application scenarios.

[0033] In the embodiments of the present application, the above ambient temperature refers to the temperature in the environment where the composite material is located. For example, when the composite material is applied in the battery assembly, the above ambient temperature refers to the temperature at the position where the composite material is provided in the battery assembly.

[0034] In some embodiments of the present application, the D90 of the endothermic particles is 10 μm - 50 μm. In some specific embodiments, the D90 of the endothermic particles is 20 μm - 40 μm. Controlling the particle size of the endothermic particles within the above range is not only conducive to the dispersion of the endothermic particles in the composite material and improving the uniformity of the composite material, but also conducive to the cooperation between the endothermic particles and the functional materials, constructing a relatively perfect network structure in the heat-insulating matrix, enabling the composite material to have a relatively perfect heat conduction - endothermic network within the endothermic temperature range, and can improve the heat insulation effect of the composite material within the heat insulation temperature range. Exemplarily, the D90 of the endothermic particles can be, but is not limited to, 10 μm, 15 μm, 20 μm, 22 μm, 25 μm, 28 μm, 30 μm, 32 μm, 35 μm, 38 μm, 40 μm, 45 μm, 50 μm, etc.

[0035] In the embodiments of the present application, a Scanning Electron Microscope (SEM) is used to measure the D90 of the endothermic particles. Specifically, the cross-section of the composite material is observed under the SEM, and the particle size value corresponding to the cumulative volume distribution percentage of the endothermic particles in the composite material reaching 90% is counted as the D90 of the endothermic particles.

[0036] In some embodiments of the present application, the sum of the mass ratios of multiple endothermic particles in the composite material is 50% - 95%. In some specific embodiments, the sum of the mass ratios of multiple endothermic particles in the composite material is 70% - 95%. Controlling the mass ratio of the endothermic particles in the composite material within the above range can enable the composite material to achieve a relatively high enthalpy value within the endothermic temperature range, with a good endothermic effect. When the endothermic particles absorb heat and undergo phase change decomposition to generate gas, the porosity or bubble content of the heat-insulating matrix can be significantly increased, thereby effectively improving the heat insulation performance of the composite material within the heat insulation temperature range. Exemplarily, the sum of the mass ratios of multiple endothermic 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.

[0037] In some embodiments of the present application, the endothermic temperature range is from the ambient temperature being greater than or equal to the phase change start temperature of the composite material to less than 160 °C. The endothermic enthalpy value of the composite material within the endothermic temperature range is 500 kJ / kg - 2000 kJ / kg; the heat insulation temperature range is when the ambient temperature is greater than or equal to 160 °C, and the endothermic enthalpy value of the composite material within the heat insulation temperature range is 100 kJ / kg - 500 kJ / kg. Exemplarily, the endothermic enthalpy value of the composite material within the endothermic temperature range can be, but is not limited to, 500 kJ / kg, 800 kJ / kg, 1000 kJ / kg, 1100 kJ / kg, 1200 kJ / kg, 1300 kJ / kg, 1500 kJ / kg, 1600 kJ / kg, 1800 kJ / kg, 2000 kJ / kg, etc. Exemplarily, the endothermic enthalpy value of the composite material within the heat insulation temperature range can 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 endothermic enthalpy value of the composite material within the endothermic temperature range is 1000 kJ / kg - 1500 kJ / kg; thus, when the composite material is applied to a battery module, when an abnormal heat generation of a single battery is relatively severe, it can better absorb the heat generated by the single battery, and at this time, the composite material is easier to obtain.

[0038] It should be noted that in the embodiments of the present application, the phase change start temperature of the composite material is measured using a Differential Scanning Calorimeter (DSC). Specifically, the sample to be measured is placed in an alumina crucible, the heating rate of the equipment 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 start temperature of the composite material". Exemplarily, the phase change start temperature of the composite material can be 70 °C, 72 °C, 75 °C, 78 °C, 80 °C, 82 °C, 85 °C, etc.

[0039] In some embodiments of the present application, the sum of the mass percentages of the functional materials in the composite material is 0.5%-20%. In some specific embodiments, the sum of the mass percentages of the functional materials in the composite material is 1%-10%. In this way, it is beneficial to balance the thermal conductivity and the endothermic enthalpy value of the composite material in the endothermic temperature range, thereby facilitating the acceleration of heat exchange of the composite material in the endothermic temperature range and promoting the functional effects of the endothermic particles at different positions of the composite material; moreover, it can reduce the radiative heat transfer of the composite material in the heat insulation temperature range, thereby facilitating the better heat insulation effect of the composite material in the heat insulation temperature range. Exemplarily, the sum of the mass percentages of the 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%, 20.0%.

[0040] In some embodiments of the present application, when the ambient temperature is greater than or equal to 25°C and less than the phase change start temperature of the composite material (when the composite material is at a temperature greater than or equal to 25°C and lower than the endothermic temperature), the thermal conductivity of the composite material is 0.1 W / (m·K)-2 W / (m·K). Exemplarily, when the ambient temperature is greater than or equal to 25°C and less than the phase change start temperature of the composite material, the thermal conductivity of the composite material can be but is not limited to 0.1 W / (m·K), 0.2 W / (m·K), 0.5 W / (m·K), 0.8 W / (m·K), 1.0 W / (m·K), 1.2 W / (m·K), 1.5 W / (m·K), 1.8 W / (m·K), 2.0 W / (m·K).

[0041] 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 endothermic temperature range of the composite material), the thermal conductivity of the composite material is 0.02 W / (m·K) - 2.0 W / (m·K). When the ambient temperature is greater than or equal to 160 °C (the heat insulation range of the composite material), the thermal conductivity of the composite material is 0.02 W / (m·K) - 0.08 W / (m·K). It should also be noted that the composite material continuously decreases with the increase of temperature within the endothermic temperature range until the temperature further rises to the heat insulation temperature range. Exemplarily, the thermal conductivity of the composite material within the endothermic temperature range can 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. Exemplarily, the thermal conductivity of the composite material within the heat insulation temperature range can 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 application, referring to ASTM C518, a thermal conductivity meter for thermal insulation materials is used to characterize the thermal conductivity of the composite material.

[0042] In some embodiments of the present application, the size of the functional material is 1 μm - 20 μm. 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. Exemplarily, the size of the functional material can be 1 μm, 2 μm, 5 μm, 8 μm, 10 μm, 12 μm, 15 μm, 18 μm, 20 μm, etc. In some specific embodiments, the size of the functional material is 2 μm - 8 μm. In this way, it is beneficial to the dispersion of the functional material in the heat insulation matrix, improving the uniformity of the internal thermal conductivity of the composite material, and also beneficial to constructing the internal thermal conductivity network of the composite material, thereby further improving the thermal protection performance of the composite material. In addition, the functional material with this size has a good anti-infrared radiation effect in the high-temperature section, and thus can improve the heat insulation ability of the material at high temperatures. The size of the functional material can be measured by a scanning electron microscope.

[0043] In some embodiments of the present application, the mass percentage of the heat-insulating matrix in the composite material is 5%-45%. In some specific embodiments, the mass percentage of the heat-insulating matrix in the composite material is 10%-20%. Having an appropriate mass percentage of the heat-insulating matrix is beneficial to the molding of the composite material, endows the composite material with certain mechanical properties, and can better wrap the heat-absorbing particles, avoiding the leakage of the heat-absorbing particles or the phase separation of the composite material, which may affect the performance of the composite material. At the same time, it can enable the composite material to play a better heat-insulating role in both the heat-absorbing temperature range and the heat-insulating temperature range, and will not occupy the proportion of other components, which is beneficial to improving the comprehensive performance of the composite material. Exemplarily, the mass percentage of the heat-insulating 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.

[0044] In some embodiments of the present application, the materials of the above-mentioned heat-insulating base material include, but are not limited to, at least one of epoxy resin, polyurethane, acrylate, polyimide, silicone rubber, and ethylene propylene diene monomer rubber. The above materials have a low thermal conductivity, that is, they have good heat-insulating properties, 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 heat-insulating matrix is selected from at least one of epoxy resin, polyurethane, and silicone rubber. In this way, the heat-insulating matrix has better heat resistance and mechanical properties, which can ensure good structural retention of the heat-insulating matrix in the heat-insulating temperature range, and thus ensure the realization of the heat-insulating performance.

[0045] In some embodiments of the present application, the composite material includes the following components in parts by weight: 5-45 parts of a heat-insulating matrix, 0.5-20 parts of a functional material, and 50-95 parts of heat-absorbing particles. With the cooperation of the above components, the heat absorption peak temperature of the composite material is 70°C-160°C; that is, the peak temperature of the endothermic peak shown by the composite material in DSC is 70°C-160°C. Exemplarily, the heat absorption peak temperature of the composite material can be 70°C, 72°C, 75°C, 78°C, 80°C, 82°C, 85°C, etc. It can be understood that when other parameters are similar, the closer the heat absorption peak temperature of the composite material is to 70°C, the more beneficial it is to control the heat spread (for example, the more beneficial it is to control the spread of heat in the battery module), so as to achieve a better protection effect. It should be noted that due to the different material selections of the heat-absorbing particles and the ratio differences of the composite materials, the heat absorption peak temperature of the composite material may be close to or approximately coincide with the phase change starting temperature, which does not affect the composite material from exerting its due effects.

[0046] In some specific embodiments, the composite material comprises the following components in parts by weight: 10 - 20 parts of a heat-insulating matrix, 1 - 10 parts of a functional material, and 70 - 90 parts of heat-absorbing particles. Thus, the composite material has both good molding properties and mechanical properties, has a good heat-absorbing and cooling effect in the heat-absorbing temperature range, and can exhibit good heat-insulating performance 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 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 greater than or equal to the phase change start temperature of the composite material and less than 160°C, the thermal conductivity of the composite material is 0.02 W / (m·K) - 2.0 W / (m·K); when the ambient temperature ≥ 160°C, the thermal conductivity of the composite material is 0.02 W / (m·K) - 0.08 W / (m·K); when the ambient temperature is greater than or equal to the phase change start temperature of the composite material and 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.

[0047] In this application, when measuring the weight ratio of each component in the composite material, the composite material can be weighed first, then the material is crushed and dissolved in deionized water, filtered. The crystalline hydrated salt material is soluble in water. Weigh the weight of the insoluble matter. Subtracting the weight of the insoluble matter from the total weight of the composite material gives the weight of the crystalline hydrated salt, and thus the mass of the crystalline hydrated salt and its weight percentage in the composite material can be obtained. Further performing thermogravimetric analysis (TGA) on the above insoluble matter can obtain the weight percentages of the heat-insulating matrix and the reinforcing material.

[0048] It can be understood that based on the material of the heat-absorbing particles defined in this application, the heat-absorbing particles absorb heat and undergo phase change decomposition into gases. In some embodiments of this application, in the heat-insulating temperature range, at least 60 wt.% of the heat-absorbing particles are thermally decomposed. DSC can be used to characterize the mass percentage of the heat-absorbing particles undergoing thermal decomposition. For example, 65 wt.% - 80 wt.% of the heat-absorbing particles are thermally decomposed, and the non-reacted and non-decomposed part can continue to absorb heat and decompose in the heat-insulating temperature range, which is beneficial to the heat exchange inside the composite material. In some specific embodiments, the heat-insulating temperature range ≥ 160°C, that is, when the ambient temperature ≥ 160°C, at least 60 wt.% of the heat-absorbing particles in the composite material are thermally decomposed. In some embodiments of this application, when the ambient temperature ≥ 160°C, at least 60 wt.% of any heat-absorbing particle is thermally decomposed.

[0049] Understandably, as described above, after the endothermic particles are thermally decomposed, gases are generated to form open pores and / or closed pores in the heat-insulating matrix. In some embodiments of the present application, when the ambient temperature is greater than or equal to the phase change starting temperature of the composite material, pores are formed in the heat-insulating matrix; when the ambient temperature ≥ 160 °C, the porosity of the heat-insulating matrix is further increased, reaching 80% or more. Of course, in some specific embodiments, the heat-insulating matrix itself has a pore structure (there is a pore structure before the endothermic particles are thermally decomposed), that is, the heat-insulating matrix is a porous material.

[0050] In some embodiments of the present application, the density of the composite material is 1000 kg / m 3 - 2500 kg / m 3 . In some specific embodiments, the density of the composite material is 1300 kg / m 3 - 2000 kg / m 3 . It should be noted that the above density refers to the density of the composite material when the endothermic particles are not thermally decomposed. Controlling the density of the composite material within the above range can enable the composite material to have good heat insulation, heat absorption performance and compression resistance, and when it is applied to the battery assembly, it can ensure that the energy density of the battery assembly is relatively high. Exemplarily, the density of the composite material can be 1000 kg / m 3 , 1200 kg / m 3 , 1500 kg / m 3 , 1800 kg / m 3 , 2000 kg / m 3 , 2200 kg / m 3 , 2400 kg / m 3 , 2500 kg / m 3 and so on.

[0051] In some embodiments of the present application, the thickness of the composite material is in the range of 0.1 mm - 10 mm. Controlling the thickness of the composite material within the above range can not only have a good heat absorption - heat insulation effect, but also be beneficial to improving the space utilization rate inside the battery assembly. Exemplarily, 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.

[0052] The embodiments of the present application also provide a battery assembly, including a plurality of single cells and the aforementioned composite material provided by the embodiments of the present application, and the composite material is disposed between adjacent single cells. Since the composite material is disposed between adjacent single cells, when one or several single cells in the above battery assembly undergo thermal runaway, the above composite material can effectively absorb and block the heat generated by the single cells, thereby effectively suppressing the spread of heat in the battery assembly, and further reducing the risk of thermal runaway of the battery assembly and improving the thermal safety performance of the battery assembly. For the structural schematic diagram of the battery assembly provided by an embodiment of the present application, please refer to Figure 1 , Figure 1 The number, relative position, size, and shape of the single cells and the composite material in

[0053] In the embodiments of the present application, the above battery assembly includes but is not limited to a battery pack or a battery module. The above single cells may be but are not limited to lithium-ion batteries, sodium-ion batteries, aluminum-ion batteries, etc. The above single cells may have any shape, for example, cylindrical, square, irregular, prismatic, etc.

[0054] In some embodiments of the present application, the above composite material is disposed between any two adjacent single cells.

[0055] The embodiments of the present application also provide an electrical device, including the battery assembly provided by the embodiments of the present application. Due to the battery assembly provided by the embodiments of the present application, the electrical device has a good market prospect.

[0056] In some embodiments of the present application, the above electrical device includes but is not limited to automobiles, consumer electronic products, electric bicycles, etc.

[0057] The embodiments of the present application also provide an energy storage system, including the battery assembly provided by the embodiments of the present application. Due to the battery assembly provided by the embodiments of the present application, the energy storage system has a high thermal safety performance.

[0058] The technical solution of the present application will be further described below in multiple embodiments.

[0059] Embodiment 1

[0060] A composite material includes endothermic particles (specifically, a eutectic of ammonium aluminum sulfate dodecahydrate with a D90 of 30 μm and sodium sulfate decahydrate), a heat-insulating matrix (specifically, silicone rubber), and a functional material (specifically, silicon carbide fibers with a diameter of 3-6 μm) in a mass ratio of 80:15:5.

[0061] Embodiment 2

[0062] A composite material includes endothermic particles (specifically barium hydroxide octahydrate with a D90 particle size of 30 μm), a heat-insulating matrix (specifically epoxy resin), and a functional material (specifically silicon carbide particles with a particle size of 3 - 6 μm) in a mass ratio of 85:10:5.

[0063] Examples 3 - 16

[0064] For convenient reading, the parameters of the composite materials in Examples 3 - 16 and Examples 1 - 2 are summarized in Table 1.

[0065] Table 1

[0066]

[0067] To highlight the beneficial effects of the embodiments of the present application, the following comparative examples are set.

[0068] Comparative Example 1

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

[0070] Performance Test

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

[0072] (2) The heat enthalpy value of the composite material was tested using a differential scanning calorimeter (DSC). Among them, the sample to be tested was placed in an alumina crucible, the heating rate of the equipment 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 was measured by referring to GB / T 4472 - 2011 Determination of density and relative density of chemical products, using the hydrostatic weighing method.

[0074] (4) Refer to "GB / T 2423.102 Environmental testing for electric and electronic products - Part 2: Test methods - Test: Temperature (low temperature, high temperature) / low air pressure / vibration (sinusoidal) combined". The sample is placed in an alternating temperature environment of -40°C to 70°C. The conversion time between the two extreme temperatures is within 3 minutes. The sample under test is maintained at each extreme temperature environment for 30 minutes, with one cycle per hour and 1000 cycles in total, for a total of 1000 hours. After the cycle, observe the leakage and phase separation of the composite material sample.

[0075] (5) Assemble the composite material and the battery cell into a battery pack for testing. Refer to the damp heat cycle requirements in "GB 38031-2020 Safety requirements for power batteries for electric vehicles". After the battery pack undergoes 5 cycles at the highest temperature of 70°C. After the test is completed, disassemble and observe the leakage of the composite material.

[0076] Table 2

[0077]

[0078] Combining the data in Table 1 and Table 2, it can be seen that the composite material provided in the embodiments of the present application exhibits good heat absorption performance and heat insulation performance in the heat absorption temperature range, still has good heat insulation performance in the heat insulation temperature range, and moreover, the performance of the composite material is stable, and there will be no leakage of the heat absorption material and phase separation of the composite material.

[0079] By comparing the data between the embodiments (Embodiments 1, 3, 4), it can be found that when the material of the heat absorption particles is the material further recommended in the present application (Embodiment 1), the enthalpy of heat absorption of the composite material in the heat absorption temperature range is relatively high, the heat absorption ability is better, the phase change start temperature and the heat absorption peak temperature of the composite material are lower, and the comprehensive protection performance is better. By comparing the data of Embodiment 2 and Embodiment 6, it can be found that when the particle size of the heat absorption particles is within the range recommended in the present application (Embodiment 2), the heat absorption effect of the composite material in the heat absorption temperature range is better. By comparing the data of Embodiments 8-12, it can be found that when the mass ratio of each material is within the range further recommended in the present application, the heat absorption performance of the composite material in the heat absorption temperature range and the heat insulation effect in the heat insulation temperature range are both better. By comparing the data of Embodiment 2 and Embodiment 15, it can be found that when the particle size of the functional material is within the range further recommended in the present application (Embodiments 8-9, 11), when the ambient temperature ≥ 160°C, the thermal conductivity of the composite material is relatively low, the heat insulation performance is better, and it is more conducive to the exertion of the protection performance of the composite material.

[0080] The above is the exemplary implementation manner of the present application. It should be noted that for those of ordinary skill in the art in the technical field, without departing from the principle of the present application, several improvements and refinements can still be made to it, and these improvements and refinements are also regarded as the protection scope of the present application.

Claims

1. A composite material, characterized in that, It includes a heat-insulating matrix, as well as functional materials and a plurality of heat-absorbing particles dispersed in the heat-insulating matrix; 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 alumina.

2. The composite material according to claim 1, characterized in that 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 percentages of the plurality of heat-absorbing particles in the composite material is 50% - 95%; optionally, the sum of the mass percentages of the plurality of heat-absorbing particles in the composite material is 70% - 95%.

4. The composite material according to any one of claims 1 to 3, characterized in that, The mass percentage of the heat-insulating matrix in the composite material is 5% - 45%; optionally, the mass percentage of the heat-insulating matrix in the composite material is 10% - 20%.

5. The composite material according to any one of claims 1-4, 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.

6. The composite material according to any one of claims 1-5, characterized in that, The sum of the mass percentages of the functional materials in the composite material is 0.5% - 20%; optionally, the sum of the mass percentages of the functional materials in the composite material is 1% - 10%.

7. The composite material according to any one of claims 1-6, 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.

8. The composite material according to any one of claims 1 to 7, characterized in that, The peak temperature of the endothermic peak of the composite material is 70°C - 160°C.

9. The composite material according to any one of claims 1 - 8, characterized in that 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).

10. The composite material according to any one of claims 1-9, 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 endothermic enthalpy value of the composite material is 500 kJ / kg - 2000 kJ / kg; when the ambient temperature is 160°C - 500°C, the endothermic 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 endothermic enthalpy value of the composite material is 1000 KJ / Kg - 1500 KJ / Kg.

11. The composite material according to any one of claims 1-10, 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.

12. The composite material according to any one of claims 1-11, 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.

13. The composite material according to any one of claims 1-12, 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 .

14. The composite material according to any one of claims 1-13, characterized in that, The thickness of the composite material is 0.1 mm - 10 mm.

15. A battery assembly, characterized in that, The battery assembly includes a plurality of single cells and the composite material as described in any one of claims 1-14, and the composite material is disposed between adjacent ones of the single cells.

16. An electrical device, characterized in that, The electrical device includes the battery assembly as described in claim 15.

17. An energy storage system, characterized in that, The energy storage system includes the battery assembly as described in claim 15.

Images