A low-temperature cross-season chemical heat storage composite material and its preparation method and application

Abstract

The present invention provides a low-temperature, trans-seasonal chemical heat storage composite material, its preparation method, and its application. The composite material comprises a porous carbon support matrix derived from a metal-organic framework and a compound represented by formula (I): MA(I), wherein M is selected from at least one of lithium, magnesium, and aluminum; and A is selected from at least one of hydroxide, sulfate, and bromide anions. The low-temperature, trans-seasonal chemical heat storage composite material of the present invention has at least the properties of efficiently storing and utilizing low-temperature thermal energy and storing thermal energy for long periods across seasons. It also has excellent heat storage density, enabling full utilization of low-temperature thermal energy such as solar energy and industrial waste heat.

Description

Technical Field

[0001] The present invention belongs to the field of heat storage functional materials and relates to a low-temperature cross-seasonal chemical heat storage composite material and a preparation method and application thereof. Background Art

[0002] With the depletion of traditional fossil energy and the increasing severity of environmental degradation, there is an urgent need to develop renewable and clean energy to alleviate the crises of global warming and energy shortages. Therefore, the development of renewable energy sources such as wind, hydro, and solar energy, as well as the recycling and utilization of industrial waste heat resources, have received extensive attention and research. However, these renewable energy sources and industrial waste heat resources are intermittent and unstable, resulting in a mismatch in time, space, and intensity between energy recycling and utilization. Therefore, it is necessary to utilize thermal storage systems to store this unstable thermal energy and, when needed, to achieve continuous and stable energy supply through these systems, thereby improving energy utilization efficiency while mitigating environmental impact. In this context, thermal energy storage systems that can effectively resolve the mismatch in the timing of energy supply and demand have shown great practical application value in the field of renewable energy.

[0003] Thermal energy storage systems are primarily categorized as sensible heat storage, latent heat storage, and chemical heat storage. Compared to the first two methods, chemical heat storage systems offer not only seasonal or long-term storage capabilities, storing summer solar energy for winter use, but also boast large heat storage capacity and negligible heat loss, making them a key focus of thermal energy storage.

[0004] Metal-organic frameworks (MOFs), a class of materials formed by linking metal ions with organic ligands, have attracted widespread attention in energy storage technology due to their open, tunable crystal structures, exceptional surface area, and porosity. However, MOFs suffer from poor tolerance to heat and humidity, significantly limiting their practical application. Recently, porous carbon materials prepared using MOFs as precursors have become increasingly popular in the energy, environmental, and catalytic fields due to their superior performance. MOF-derived porous carbon materials inherit the MOFs' advantages of large surface area, high porosity, and excellent customizability, while also possessing the excellent stability and thermal conductivity of carbon materials. These materials hold great potential for application as supporting matrices compared to traditional carbon materials. However, compared to their extensive research in other fields, MOF-derived porous carbon materials have been relatively understudied for thermal energy storage, particularly chemical heat storage.

[0005] Among various chemical thermal storage systems, chemical thermal storage materials based on hydrated salts and their derivatives have attracted extensive research and attention due to the readily available and inexpensive raw water, the high safety of the system, and the simple hydration-dehydration reaction mechanism. However, the application temperature of most thermal storage materials is relatively high, making the effective utilization of abundant low-temperature thermal energy (such as industrial waste heat resources and solar thermal energy) a shortcoming in the large-scale practical application of chemical thermal storage technology. Therefore, hydrated salt chemical thermal storage composites with the advantages of low reaction temperature, excellent storage performance, and no side reaction effects have become alternative materials for fully utilizing the field of low-temperature thermal energy. Despite this, there is still much room for improvement in the thermal storage performance and storage cycle of pure hydrated salt chemical thermal storage materials for low-temperature thermal energy, which greatly increases the gap between their practical application as chemical thermal storage materials. Therefore, how to develop a hydrated salt chemical thermal storage composite material that can fully utilize and store low-temperature thermal energy for a long time and has good storage performance remains an extremely difficult task. Summary of the Invention

[0006] In order to improve the above technical problems, the present invention provides a composite material, which includes a porous carbon support matrix derived from a metal organic framework and a compound represented by formula (I) compounded with the matrix:

[0007] MA (I)

[0008] Wherein, M is selected from at least one of lithium, magnesium and aluminum;

[0009] A is selected from at least one of hydroxide, sulfate, and bromide anions.

[0010] According to an embodiment of the present invention, the compound represented by formula (I) is selected from at least one of lithium hydroxide, magnesium sulfate, lithium bromide, and aluminum sulfate.

[0011] According to an embodiment of the present invention, the metal-organic framework-derived porous carbon support matrix refers to a porous carbon material prepared by carbonizing a metal-organic framework through heat treatment and removing the metal components therein.

[0012] Preferably, the heat treatment refers to treatment under heating conditions, such as calcination treatment, and the heating temperature may be 600-900°C.

[0013] According to an embodiment of the present invention, the metal-organic framework comprises a metal element and an organic ligand. The metal element is at least one selected from zinc and cobalt, preferably zinc; and the organic ligand is at least one selected from 2-methylimidazole, terephthalic acid, benzimidazole, and 2-nitroimidazole, preferably 2-methylimidazole.

[0014] According to an embodiment of the present invention, the mass content of the compound represented by formula (I) in the composite material is 5-90%, for example, 10-80%, more preferably 30-60%, and exemplified by 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, and 90%.

[0015] According to an embodiment of the present invention, the composite material is a low-temperature chemical heat storage composite material.

[0016] According to an embodiment of the present invention, the composite material is capable of storing thermal energy for a long period of time.

[0017] In the present invention, the composite material can store heat at higher temperatures and release heat at lower temperatures. For example, the composite material can store heat in the summer when temperatures are higher and release heat in the winter when temperatures are lower, thus enabling cross-seasonal heat storage.

[0018] According to an embodiment of the present invention, the energy density of the composite material is not less than 1000 kJ kg -1 , for example, energy density is 1000-1600 kJ kg -1 , exemplified by 1000 kJ kg -1 、1183.4kJ kg -1 、1225.8kJ kg -1 、1241.9kJkg -1 、1330kJ kg -1 、1423.7kJ kg -1 、1570.2kJ kg -1 、1600kJ kg -1 .

[0019] According to an embodiment of the present invention, the peak exotherm temperature of the composite material is 100-110°C, for example 102-108°C, exemplified by 100°C, 102°C, 103.7°C, 104.4°C, 105.2°C, 106.5°C, 107.3°C, 108°C, 110°C.

[0020] The present invention also provides a method for preparing the composite material, which comprises the following steps:

[0021] (1) reacting a metal salt and an organic ligand in a solvent to prepare a metal-organic framework;

[0022] (2) heating the metal organic framework in step (1) under an inert atmosphere, and then removing the metal salt in an acidic solution to prepare a metal organic framework-derived porous carbon support matrix;

[0023] (3) Mixing the porous carbon support matrix derived from the metal organic framework in step (2) with the compound represented by formula (I) or a hydrate of the compound represented by formula (I) in water to prepare the composite material.

[0024] According to an embodiment of the present invention, in step (1), the molar ratio of the metal salt to the organic ligand is 1:(4-6), exemplified by 1:4, 1:4.5, 1:5, 1:5.5, and 1:6.

[0025] According to an embodiment of the present invention, the metal salt is selected from at least one of Zn(NO3)2·6H2O and Co(NO3)2·6H2O, preferably Zn(NO3)2·6H2O.

[0026] According to an embodiment of the present invention, step (1) specifically comprises: uniformly dispersing the metal salt and the organic ligand in a solvent, and then reacting them to prepare a metal organic framework.

[0027] According to an embodiment of the present invention, in step (1), the amount of the metal salt is 2-10 parts by mole, such as 3-8 parts by mole, exemplified by 2 parts by mole, 3 parts by mole, 4 parts by mole, 5 parts by mole, 8 parts by mole, and 10 parts by mole.

[0028] According to an embodiment of the present invention, in step (1), the reaction time is 0.5-2 hours, for example, 0.5 hours, 1.0 hours, 1.5 hours, or 2 hours.

[0029] According to an embodiment of the present invention, in step (1), the reaction temperature is 15-50°C, for example, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C.

[0030] According to an embodiment of the present invention, the solvent is selected from at least one of methanol, water, ethanol, n-propanol, n-butanol, and 2-butanol.

[0031] According to an embodiment of the present invention, in step (1), the metal salt may be first dissolved in a solvent and then added dropwise to the organic ligand solution, wherein the organic ligand solution is an organic ligand dissolved in a solvent.

[0032] According to an embodiment of the present invention, ultrasonic dispersion or stirring can be used for uniform dispersion.

[0033] According to an embodiment of the present invention, in step (1), after the reaction is completed, the reaction product is centrifuged, and the precipitate is washed and vacuum-dried to prepare a metal organic framework.

[0034] According to an embodiment of the present invention, in step (1), the precipitate is washed with methanol at least 4 times; and the vacuum drying temperature is 40-60°C, such as 40°C, 50°C, or 60°C.

[0035] According to an embodiment of the present invention, in step (2), the inert atmosphere can be provided by any one or more of nitrogen, argon, helium, etc., preferably nitrogen or argon.

[0036] According to an embodiment of the present invention, in step (2), the heating temperature is 600-900°C, for example, 600°C, 700°C, 800°C, 900°C.

[0037] According to an embodiment of the present invention, in step (2), the heating rate during heating is 3-10°C / min, for example, 3°C / min, 5°C / min, 7°C / min, 9°C / min, 10°C / min.

[0038] According to an embodiment of the present invention, in step (2), the heating time is 3-5 hours, for example, 3 hours, 4 hours, or 5 hours.

[0039] According to an embodiment of the present invention, in step (2), after heating is completed, the product is cooled to room temperature at a cooling rate of 3-10°C / min, for example, 3°C / min, 5°C / min, 7°C / min, 9°C / min, 10°C / min.

[0040] According to an embodiment of the present invention, in step (2), the acidic solution is an acidic aqueous solution, wherein the concentration of the acidic solution is 1-4 mol / L, for example, 1 mol / L, 2 mol / L, 3 mol / L, or 4 mol / L. Furthermore, the acidic solution is selected from any one of nitric acid solution, sulfuric acid solution, and hydrochloric acid, preferably hydrochloric acid.

[0041] According to an embodiment of the present invention, in step (2), after removing the metal salt, the product is washed to neutrality and then vacuum dried; for example, the vacuum drying temperature is 60-80° C., such as 60° C., 70° C., or 80° C. For example, deionized water can be used for washing.

[0042] According to an embodiment of the present invention, in step (3), the hydrate of the compound represented by formula (I) is selected from at least one of lithium hydroxide monohydrate, magnesium sulfate heptahydrate, lithium bromide monohydrate, and aluminum sulfate 18hydrate.

[0043] According to an embodiment of the present invention, step (3) is specifically: the porous carbon support matrix derived from the metal organic framework in step (2) is mixed evenly with the compound represented by formula (I) or the hydrate of the compound represented by formula (I) in water, and heated to react to prepare the composite material.

[0044] According to an embodiment of the present invention, in step (3), the mass ratio of the metal organic framework derived porous carbon support matrix to the compound represented by formula (I) is 1: (0.3-2.4), preferably 1: (0.4-1.6), for example 1: (0.4-1.5), and exemplified by 1: 0.3, 1: 0.4, 1: 0.43, 1: 0.5, 1: 0.67, 1: 1.0, 1: 1.50, 1: 1.6, 1: 1.8, 1: 2, and 1: 2.4. For example, the amount of the metal organic framework derived porous carbon support matrix is ​​50-100 mg, preferably 50 mg.

[0045] According to an embodiment of the present invention, in step (3), the metal organic framework-derived porous carbon support matrix in step (3) and the compound represented by formula (I) or the hydrate of the compound represented by formula (I) are stirred and mixed uniformly in water at room temperature, and the stirring time is 1-5 hours, preferably 3 hours.

[0046] According to an embodiment of the present invention, in step (3), the reaction temperature is 120-180°C, preferably 160°C. For example, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C.

[0047] According to an embodiment of the present invention, in step (3), the reaction time is 10-20 hours, such as 12-18 hours, exemplified by 10 hours, 12 hours, 15 hours, 16 hours, 18 hours, and 20 hours.

[0048] According to an embodiment of the present invention, in step (3), after the reaction is completed, the reaction product is dried to obtain a composite material. For example, the drying temperature is 90 to 100° C., preferably 100° C., and the drying time is 3 to 7 hours, preferably 5 hours.

[0049] According to a preferred embodiment of the present invention, the method for preparing the composite material specifically comprises the following steps:

[0050] (1) gradually adding dropwise 60 mL of a methanol solution containing Zn(NO3)2·6H2O to a vigorously stirred 60 mL of a methanol solution containing 2-methylimidazole, and continuing to stir after the addition is completed, to prepare a mixture; aging the mixture for 4 hours and then centrifuging it; washing the precipitate with methanol at least 4 times and vacuum drying it overnight to prepare a metal-organic framework;

[0051] (2) heating the metal organic framework powder in step (1) under an argon atmosphere; after heating, cooling to room temperature, immersing the obtained black powder in an HCl solution and stirring to remove Zn(NO3)2·6H2O; finally, filtering the crude product, washing it with deionized water until it is neutral, and then vacuum drying it overnight to prepare a metal organic framework-derived porous carbon support matrix;

[0052] (3) The metal organic framework-derived porous carbon support matrix described in step (2) and the hydrate of the compound represented by formula (I) are added to 50 mL of deionized water and stirred at room temperature. The mixture is then transferred to a steel autoclave lined with a 100 mL polytetrafluoroethylene liner and heated in an oven. After the autoclave is cooled to room temperature, the resulting black solution is dried at 100° C. for 5 hours to prepare the low-temperature cross-seasonal chemical heat storage composite material.

[0053] The present invention also provides a heat storage device comprising the composite material.

[0054] The present invention also provides the use of the composite material in low-temperature thermal energy storage devices, preferably the use of the composite material in the fields of solar energy, industrial waste heat treatment, etc.

[0055] Beneficial effects of the present invention:

[0056] (1) The low-temperature inter-seasonal chemical heat storage composite material of the present invention utilizes porous carbon derived from a metal organic framework as a supporting matrix and is compounded with the compound represented by formula (I). Scanning electron microscopy observation shows that the inorganic hydrated salt is successfully compounded with the porous carbon supporting matrix derived from the metal organic framework to prepare a low-temperature inter-seasonal chemical heat storage composite material.

[0057] (2) The low-temperature, cross-season chemical heat storage composite material of the present invention has at least the performance of efficiently storing and utilizing low-temperature thermal energy and storing thermal energy for a long time across seasons, and further has excellent heat storage density. It can fully utilize low-temperature thermal energy such as solar energy and industrial waste heat. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 This is a scanning electron microscope image of the metal organic framework-derived porous carbon support matrix prepared in Example 3 of the present invention.

[0059] Figure 2 This is a scanning electron microscope image of the low-temperature cross-seasonal chemical heat storage composite material prepared in Example 3 of the present invention.

[0060] Figure 3 X-ray diffraction characterization patterns of the metal-organic framework-derived porous carbon support matrix, low-temperature trans-seasonal chemical heat storage composite material, and pure lithium hydroxide prepared in Example 3 of the present invention.

[0061] Figure 4 This is a differential scanning calorimetry spectrum of the low-temperature cross-seasonal chemical heat storage composite material prepared in Example 3 of the present invention. DETAILED DESCRIPTION

[0062] The technical solutions of the present invention will be described in further detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanations of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are encompassed within the scope of protection that the present invention is intended to protect.

[0063] Unless otherwise specified, the raw materials and reagents used in the following examples are commercially available or can be prepared by known methods.

[0064] The energy density test method of each composite material in the following Examples 1-4 is as follows:

[0065] First, the low-temperature, trans-seasonal chemical heat storage composite materials prepared in Examples 1-4 were fully hydrated and then subjected to energy storage for 60 minutes. After completion of energy storage, they were tested by DSC. The initial DSC temperature was set to 30°C and stabilized for 15 minutes. Then, the temperature was increased to 200°C at a rate of 5°C / min to test its energy storage.

[0066] Example 1

[0067] 1) Preparation of a Metal-Organic Framework-Derived Porous Carbon Support Matrix: A 60 mL methanol solution containing 3 mmol Zn(NO₃)₂·6H₂O was gradually added dropwise to a vigorously stirred 60 mL methanol solution containing 18 mmol 2-methylimidazole. Stirring was continued at room temperature for 60 minutes. The mixture was then aged for 4 hours and centrifuged. The precipitate was washed at least four times with methanol. After vacuum drying at 50°C overnight, a Metal-Organic Framework (MOF) powder was obtained. The MOF powder was heated to 600°C under an argon atmosphere at a heating rate of 5°C / min and held for 3 hours. After cooling to room temperature at a cooling rate of 5°C / min, the resulting black powder was immersed in a 2 mol / L HCl solution with stirring to remove the zinc component. The crude product was filtered, washed with deionized water until neutral, and then vacuum dried at 80°C overnight to obtain a Metal-Organic Framework-Derived Porous Carbon Support Matrix.

[0068] 2) Preparation of low-temperature interseasonal chemical heat storage composite material: 50 mg of the prepared metal organic framework-derived porous carbon support matrix and 21.4 mg of lithium hydroxide monohydrate were added to 50 mL of deionized water and stirred at room temperature for 3 hours. The mixture was then transferred to a steel autoclave lined with a 100 mL polytetrafluoroethylene liner and kept in an oven at 160°C for 12 hours. After the autoclave was cooled to room temperature, the resulting black solution was dried at 100°C for 5 hours to obtain the low-temperature interseasonal chemical heat storage composite material. The mass content of lithium hydroxide in the composite material is 30%, and the heat storage density reaches 1241.9 kJ·kg -1 .

[0069] Example 2

[0070] 1) Preparation of a Metal-Organic Framework-Derived Porous Carbon Support Matrix: A 60 mL methanol solution containing 4 mmol Zn(NO₃)₂·6H₂O was gradually added dropwise to a vigorously stirred 60 mL methanol solution containing 20 mmol 2-methylimidazole. Stirring was continued at room temperature for 60 minutes. The mixture was then aged for 4 hours and centrifuged. The precipitate was washed at least four times with methanol. After vacuum drying at 50°C overnight, a Metal-Organic Framework (MOF) powder was obtained. The MOF powder was heated to 700°C under an argon atmosphere at a heating rate of 5°C / min and held for 4 hours. After cooling to room temperature at a cooling rate of 5°C / min, the resulting black powder was immersed in a 2 mol / L HCl solution with stirring to remove the zinc component. The crude product was filtered, washed with deionized water until neutral, and then vacuum dried at 80°C overnight to obtain a Metal-Organic Framework-Derived Porous Carbon Support Matrix.

[0071] 2) Preparation of low-temperature interseasonal chemical heat storage composite material: 50 mg of the prepared metal organic framework-derived porous carbon support matrix and 33.3 mg of lithium hydroxide monohydrate were added to 50 mL of deionized water and stirred at room temperature for 3 hours. The mixture was then transferred to a steel autoclave lined with a 100 mL polytetrafluoroethylene liner and kept in an oven at 160°C for 15 hours. After the autoclave was cooled to room temperature, the resulting black solution was dried at 100°C for 5 hours to obtain the low-temperature interseasonal chemical heat storage composite material. The mass content of lithium hydroxide in the composite material is 40%, and the heat storage density reaches 1330 kJ·kg -1 .

[0072] Example 3

[0073] 1) Preparation of a Metal-Organic Framework-Derived Porous Carbon Support Matrix: A 60 mL methanol solution containing 5 mmol Zn(NO₃)₂·6H₂O was gradually added dropwise to a vigorously stirred 60 mL methanol solution containing 20 mmol 2-methylimidazole. Stirring was continued at room temperature for 60 minutes. The mixture was then aged for 4 hours and centrifuged. The precipitate was washed at least four times with methanol. After vacuum drying at 60°C overnight, a Metal-Organic Framework (MOF) powder was obtained. The MOF powder was heated to 800°C under an argon atmosphere at a heating rate of 5°C / min and held for 5 hours. After cooling to room temperature at a cooling rate of 5°C / min, the resulting black powder was immersed in a 2 mol / L HCl solution with stirring to remove the zinc component. The crude product was filtered, washed with deionized water until neutral, and then vacuum dried at 80°C overnight to obtain a Metal-Organic Framework-Derived Porous Carbon Support Matrix.

[0074] 2) Preparation of low-temperature interseasonal chemical heat storage composite material: 50 mg of the prepared metal organic framework-derived porous carbon support matrix and 50 mg of lithium hydroxide monohydrate were added to 50 mL of deionized water and stirred at room temperature for 3 hours. The mixture was then transferred to a steel autoclave lined with a 100 mL polytetrafluoroethylene liner and kept in an oven at 160°C for 16 hours. After the autoclave was cooled to room temperature, the resulting black solution was dried at 100°C for 5 hours to obtain the low-temperature interseasonal chemical heat storage composite material. The mass content of lithium hydroxide in the composite material is 50%, and the heat storage density reaches 1570.2 kJ·kg -1 .

[0075] Example 4

[0076] 1) Preparation of a Metal-Organic Framework-Derived Porous Carbon Support Matrix: A 60 mL methanol solution containing 8 mmol Zn(NO₃)₂·6H₂O was gradually added dropwise to a vigorously stirred 60 mL methanol solution containing 32 mmol 2-methylimidazole. Stirring was continued at room temperature for 60 minutes. The mixture was then aged for 4 hours and centrifuged. The precipitate was washed at least four times with methanol. After vacuum drying at 60°C overnight, a Metal-Organic Framework (MOF) powder was obtained. The MOF powder was heated to 800°C under an argon atmosphere at a heating rate of 5°C / min and held for 5 hours. After cooling to room temperature at a cooling rate of 5°C / min, the resulting black powder was immersed in a 2 mol / L HCl solution with stirring to remove the zinc component. The crude product was filtered, washed with deionized water until neutral, and then vacuum dried at 80°C overnight to obtain a Metal-Organic Framework-Derived Porous Carbon Support Matrix.

[0077] 2) Preparation of low-temperature interseasonal chemical heat storage composite material: 50 mg of the prepared metal organic framework-derived porous carbon support matrix and 75 mg of lithium hydroxide monohydrate were added to 50 mL of deionized water and stirred at room temperature for 3 hours. The mixture was then transferred to a steel autoclave lined with a 100 mL polytetrafluoroethylene liner and kept in an oven at 160°C for 18 hours. After the autoclave was cooled to room temperature, the resulting black solution was dried at 100°C for 5 hours to obtain the low-temperature interseasonal chemical heat storage composite material. The mass content of lithium hydroxide in the composite material is 60%, and the heat storage density reaches 1423.7 kJ·kg -1 .

[0078] Figure 1 and Figure 2 They are scanning electron micrographs of the metal organic framework-derived porous carbon support matrix prepared in Example 3 and scanning electron micrographs of the low-temperature cross-seasonal chemical heat storage composite material, as shown in FIG. Figure 2 As shown, it can be clearly seen that the lithium hydroxide particles are composited on the surface of the low-temperature cross-seasonal chemical heat storage composite material; Figure 1 No other particles were observed on the surface of the metal-organic framework-derived porous carbon support matrix, indicating the successful composite of lithium hydroxide and the metal-organic framework-derived porous carbon support matrix.

[0079] Figure 3 X-ray diffraction characterization patterns of the metal-organic framework-derived porous carbon support matrix (i.e., porous carbon support matrix), the low-temperature transseasonal chemical heat storage composite material, and pure lithium hydroxide prepared in Example 3. It can be clearly seen from the figure that the low-temperature transseasonal chemical heat storage composite material exhibits characteristic diffraction peaks consistent with lithium hydroxide, and the amorphous carbon diffraction peaks attributed to the metal-organic framework-derived porous carbon support matrix can also be clearly observed at 25°C, which further proves the successful preparation of the low-temperature transseasonal chemical heat storage composite material.

[0080] Figure 4 The differential scanning calorimetry spectrum of the low-temperature cross-seasonal chemical heat storage composite material of Example 3 shows that the peak exothermic temperature of the material is 105.2°C, and the obtained heat storage density reaches 1570.2 kJ kg -1 These results indicate that the low-temperature, cross-seasonal chemical heat storage composite material of the present invention has excellent performance in terms of efficient storage and utilization of low-temperature thermal energy and heat storage density, which is conducive to further fully utilizing low-temperature thermal energy such as solar energy and industrial waste heat for thermal energy storage.

[0081] In the present invention, the molar ratio of the metal salt and the organic ligand, for example, the molar ratio of the Zn(NO3)2·6H2O and 2-methylimidazole, or the heating temperature, or the heating rate, or the heating time, or the concentration of the acidic solution, or the mass ratio of the metal organic framework-derived porous carbon support matrix and the compound represented by formula (I), or the reaction temperature of each step, etc., are adjusted within the scope of this application to achieve the preparation of a low-temperature trans-seasonal chemical heat storage composite material, and exhibit heat storage density and heat release performance basically consistent with Example 3.

[0082] The above is an exemplary description of the embodiments of the present invention. However, the scope of protection of the present invention is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc. made by those skilled in the art within the spirit and principles of the present invention shall be included in the scope of protection of the present invention.

Claims

1. A composite material, characterized in that: The composite material includes a porous carbon support matrix derived from a metal organic framework and a compound represented by formula (I) composited with the matrix: MA (I) wherein M is selected from lithium; A is selected from hydroxide; The compound represented by formula (I) is selected from lithium hydroxide; The mass content of the compound represented by formula (I) is 50%; The metal organic framework comprises a metal element and an organic ligand; wherein the metal element is selected from zinc; the organic ligand is selected from 2-methylimidazole; The metal organic framework-derived porous carbon support matrix refers to a porous carbon material prepared by carbonizing a metal organic framework through heat treatment and removing the metal components therein; The preparation method of the composite material is as follows: 1) Preparation of a metal-organic framework-derived porous carbon support matrix: 60 mL of a methanol solution containing 5 mmol Zn(NO3)2·6H2O was gradually added dropwise to a vigorously stirred 60 mL methanol solution containing 20 mmol 2-methylimidazole. After the addition was completed, stirring was continued at room temperature for 60 minutes. The mixture was then aged for 4 hours and then centrifuged. The precipitate was washed with methanol at least four times. After vacuum drying at 60°C overnight, a metal-organic framework powder was prepared. The obtained metal-organic framework powder was heated to 800°C at a heating rate of 5°C / min under an argon atmosphere and maintained for 5 hours. After cooling to room temperature at a cooling rate of 5°C / min, the obtained black powder was immersed in HCl solution (2 mol / L) and stirred to remove the zinc component in the sample. Finally, the crude product was filtered, washed with deionized water until neutral, and then vacuum dried at 80°C overnight to obtain a metal-organic framework-derived porous carbon support matrix. 2) Preparation of low-temperature interseasonal chemical heat storage composite material: 50 mg of the prepared metal-organic framework-derived porous carbon support matrix and 50 mg of lithium hydroxide monohydrate were added to 50 mL of deionized water and stirred at room temperature for 3 hours; the mixture was then transferred to a steel autoclave lined with a 100 mL polytetrafluoroethylene liner and kept in an oven at 160 °C for 16 hours; after the autoclave was cooled to room temperature, the resulting black solution was dried at 100 °C for 5 hours to obtain a low-temperature interseasonal chemical heat storage composite material.

2. The composite material according to claim 1, characterized in that The composite material is a low-temperature chemical heat storage composite material.

3. A heat storage device, characterized in that: The composite material comprises the composite material according to any one of claims 1 to 2.

4. Use of the composite material according to any one of claims 1 to 2 in a low-temperature thermal energy storage device.

5. The use according to claim 4, characterized in that Application in the fields of solar energy and industrial waste heat treatment.

Images