A sintering-resistant medium-high temperature thermochemical heat storage material based on sandwich particle structure, and a preparation method and application thereof

Abstract

The present application relates to a kind of anti-sintering high temperature thermochemical heat storage material based on sandwich particle structure and its preparation method and application, belong to heat storage material technical field.To solve the problem that existing thermochemical heat storage material is easy to sinter, poor in heat conduction and performance is easily destroyed at medium-high temperature, the present application provides a kind of anti-sintering high temperature thermochemical heat storage material based on sandwich particle structure, including granular heat storage functional matrix material and sheet inert doping material, sheet inert doping material is dispersed in granular heat storage functional matrix material layer by layer, granular heat storage functional matrix material is spaced layer by layer, and the anti-sintering high temperature thermochemical heat storage material of multilayer sandwich particle structure is formed.The sintering condition of thermochemical heat storage material is improved by optimizing the structure of thermochemical heat storage material, and its heat conduction and heat transfer performance are also enhanced synchronously, indirectly increase the heat storage amount / heat release amount of medium-high temperature thermochemical heat storage material when storing heat / heat releasing.

Description

Technical Field

[0001] This invention belongs to the field of thermal energy storage materials technology, and particularly relates to a high-temperature thermochemical thermal energy storage material based on a sandwich particle structure that prevents sintering, as well as its preparation method and application. Background Technology

[0002] Thermochemical thermal energy storage technology utilizes reversible vapor-solid reactions to convert conventional thermal energy into chemical energy for storage, enabling seasonal thermal energy storage and long-distance heat transfer under ambient temperature conditions. It is a reliable high-density energy storage method that can store thermal energy in the range of 150–1000℃, including solar energy, industrial waste heat, and high-temperature flue gas heat.

[0003] Medium- and high-temperature vapor-solid thermochemical thermal storage materials mainly include carbonates, hydroxides, metal oxides, and multioxides. Different storage materials have different storage densities and storage temperatures, thus they can be applied to different fields. With continuous technological exploration, various thermal storage materials have received widespread attention. Different thermochemical thermal storage materials and systems are currently undergoing small-scale to pilot-scale testing in the laboratory. For example, CaO / Ca(OH)2, MgO / Mg(OH)2, and PbO / PbCO3 are all promising candidate materials.

[0004] The study of heat storage and release through the reaction of oxides and water vapor is a typical thermochemical heat storage reaction, covering a temperature range from low to medium temperatures to high temperatures, mainly involving the hydration and decomposition processes of metal oxides. MgO / Mg(OH)₂ at low to medium temperatures and CaO / Ca(OH)₂ at medium to high temperatures are currently the two most studied heat storage materials, showing great promise due to their low cost and large reserves. However, both materials have extremely low thermal conductivity, approximately 0.1-0.2 W / (m·K), resulting in very poor heat transfer between the sample's interior and exterior. The reaction cannot proceed smoothly from the surface to the particle center, and hydration / decomposition is largely limited by heat transfer issues.

[0005] More importantly, during the heat storage / exothermic reaction process, medium- and high-temperature thermochemical heat storage materials are prone to agglomeration / caking due to the presence of water vapor and the adhesion of hydrophilic water molecules. This agglomeration leads to physical sintering in the high-temperature atmosphere, affecting the heat storage and exothermic processes, damaging the material's inherent thermal properties, and causing performance degradation or even failure. These problems severely limit the widespread adoption of existing medium- and high-temperature thermochemical heat storage materials in large-scale commercial applications. Summary of the Invention

[0006] To address the problems of existing thermochemical thermal storage materials being prone to sintering, having poor thermal conductivity, and having their performance easily damaged at medium and high temperatures, this invention provides a sintering-resistant medium- and high-temperature thermochemical thermal storage material based on a sandwich particle structure, along with its preparation method and application.

[0007] The technical solution of the present invention:

[0008] A high-temperature thermochemical thermal storage material with anti-sintering based on a sandwich particle structure includes a granular thermal storage functional matrix material and a sheet-like inert dopant material. The sheet-like inert dopant material is dispersed layer by layer in the granular thermal storage functional matrix material, and the granular thermal storage functional matrix material is spaced layer by layer to form a multi-layer sandwich particle structure anti-sintering high-temperature thermochemical thermal storage material.

[0009] Furthermore, the doping amount of the sheet-like inert doped material is 1 to 10 wt%.

[0010] Furthermore, the granular thermal storage matrix material includes one or a combination of several of the following: metal oxide / hydroxide particles, metal oxide / carbonate particles, multi-component oxide particles, or metal hydride particles; the metal oxide / hydroxide particles include CaO / Ca(OH)2 particles, MgO / Mg(OH)2 particles, or Al2O3 / Al(OH)3 particles; the metal oxide / carbonate particles include CaO / CaCO3 particles, MgO / MgCO3 particles, PbO / PbCO3 particles, or SrO / SrCO3 particles; the multi-component oxide particles include FeO / Fe2O3 particles, BaO / BaO2 particles, CoO / Co3O4 particles, or Mn3O4 / Mn2O3 particles; and the metal hydride particles include MgH / Mg particles or AlH / Al particles.

[0011] Furthermore, the sheet-like inert doped material includes coated sheet-like materials, powdered sheet-like materials, nanosheet-like materials, metal sheet-like materials, or ceramic sheet-like materials; the coated sheet-like materials include ZnO or zinc-based chromium salts; the powdered sheet-like materials include CaTiO3 or MgCl2; the nanosheet-like materials include graphene or nano LiCoO2; the metal sheet-like materials include sheet-like nickel powder or zinc-aluminum alloys; and the ceramic sheet-like materials include Al2O3 or AlN.

[0012] Furthermore, the particle size of the granular thermal storage functional matrix material is 100-200 nm; the particle size of the sheet-like inert doped material is 500-1000 nm and the thickness is 10-20 nm.

[0013] A method for preparing a high-temperature thermochemical thermal storage material with anti-sintering properties based on a sandwiched particle structure includes the following steps:

[0014] Step 1: Determine the amount of lamellar inert dopant to be added based on the degree of sintering of the granular thermal storage functional matrix material during conventional thermal storage / release.

[0015] Step 2: Add sheet-like inert dopant to the granular thermal storage matrix material and fully mix it by low-frequency ultrasonic dispersion to form a uniform multilayer sandwich particle structure.

[0016] Furthermore, the sintering degree of the particulate thermal storage matrix material is defined by its porosity state. When sintering causes the porosity to be below 50%, it is defined as an over-burned state, in which the doping amount of the lamellar inert doped material is 8-10 wt%. When sintering causes the porosity to be 50-70%, it is defined as an under-burned state, in which the doping amount of the lamellar inert doped material is 4-6 wt%. When the porosity is 70%-90%, it is defined as a normal state, in which the doping amount of the lamellar inert doped material is 1-2 wt%.

[0017] Furthermore, the ultrasonic frequency of the low-frequency ultrasonic dispersion is 10-20 kHz, and the ultrasonic dispersion time is 5-10 min.

[0018] Application of a high-temperature thermochemical thermal storage material based on sandwich particle structure for sintering prevention in seasonal thermal storage and long-distance heat transfer.

[0019] Furthermore, the heat storage / heat release temperature range of the medium-high temperature thermochemical heat storage material is 150–700℃, of which the medium temperature range is 150–350℃ and the high temperature range is 350–700℃.

[0020] The beneficial effects of this invention are:

[0021] This invention relates to a high-temperature thermochemical thermal storage material with a sandwiched particle structure that prevents sintering. By doping the granular thermal storage functional matrix material with lamellar inert dopants, the granular thermal storage functional matrix material is uniformly separated, forming a multi-layered sandwiched particle structure at the microscopic level. This avoids particle stacking and alleviates the adsorption and agglomeration between particles caused by hydrophilic groups during water vapor permeation. As a result, the thermochemical thermal storage material will not sinter or fail due to excessively high temperatures, whether in a high-temperature thermal storage state or a high-temperature exothermic state.

[0022] Due to the optimization of the material structure, the high-temperature thermochemical thermal energy storage material based on sandwich particle structure provided by this invention achieves the optimization of the heat transfer path, thereby simultaneously enhancing the thermal conductivity and heat transfer performance of the material. The heat in the decomposition / hydration reaction process can be smoothly introduced and exported. Since the heat can be smoothly released and absorbed, the heat is applied in a timely manner during the heat exchange process. Characterization tests show that, compared with the pure material, the material's energy storage density is increased.

[0023] The present invention has a simple preparation process, low cost, and the sheet-like inert doping material does not affect the performance of the granular thermal storage matrix material. It can effectively prevent sintering, improve thermal conductivity and heat transfer, and indirectly increase thermal storage density. It is beneficial to theoretical research at the microscale and can solve practical problems in engineering, which has important dual significance. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the microscopic mechanism of the anti-sintering high-temperature thermochemical thermal storage material based on sandwich particle structure of the present invention; in the figure, 101 is a sheet-like inert doped material, 102 is a granular thermal storage functional matrix material, and 103 is a multilayer sandwich particle structure.

[0025] Figure 2 The images shown are high-vacuum scanning electron microscope (SEM) images and microscopic diagrams of the anti-sintering high-temperature thermochemical thermal energy storage material based on sandwich particle structure provided in Example 2; in the figures, 401 is CaTiO3 powder flake material, 402 is magnesium hydroxide particles, and 403 is the sandwich structure observed under the electron microscope.

[0026] Figure 3 This is a SEM image of magnesium hydroxide particles before thermal storage.

[0027] Figure 4 This is a SEM image of magnesium hydroxide particles after thermal storage.

[0028] Figure 5 SEM micrograph of the anti-sintering high-temperature thermochemical thermal storage material prepared in Example 2 before thermal storage;

[0029] Figure 6 This is a SEM image of the anti-sintering high-temperature thermochemical thermal storage material prepared in Example 2 after thermal storage.

[0030] Figure 7 A comparison of the residual mass ratio and heat flow curves of magnesium hydroxide particles and the anti-sintering high-temperature thermochemical thermal storage material prepared in Example 2, as measured by a comprehensive calorimeter.

[0031] Figure 8 A comparison of the enthalpy of magnesium hydroxide particles and the anti-sintering high-temperature thermochemical heat storage material prepared in Example 2, and a comparison of the residual mass ratio after heat storage is completed.

[0032] Figure 9 This is a schematic diagram illustrating the principle of magnesium hydroxide particles sintering in a water vapor atmosphere, where 301 represents magnesium atoms, 302 represents oxygen atoms, 303 represents hydrogen atoms, 304 represents water molecules, and 305 represents the agglomerated material block formed by sintering. Detailed Implementation

[0033] The technical solution of the present invention will be further described below with reference to embodiments, but it is not limited thereto. Any modifications or equivalent substitutions to the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention should be covered within the protection scope of the present invention. In the following embodiments, the process equipment or apparatus not specifically specified are all conventional equipment or apparatus in the art. Unless otherwise specified, the raw materials used in the embodiments of the present invention are all commercially available; unless otherwise specified, the technical means used in the embodiments of the present invention are all conventional means well known to those skilled in the art.

[0034] Example 1

[0035] This embodiment provides a high-temperature thermochemical thermal storage material based on a sandwich particle structure that prevents sintering and its preparation method.

[0036] In this embodiment, the granular thermal storage matrix material is magnesium hydroxide particles with a particle size of 100–200 nm. The thermal storage and release processes are achieved through the transformation between magnesium oxide and magnesium hydroxide, exhibiting a relatively stable pressure and temperature change process. The sheet-like inert dopant material is CaTiO3 powder sheet material with a particle size of 500–1000 nm and a thickness of 10–20 nm. The equivalent size of the CaTiO3 powder sheet material is significantly larger than the particle diameter, and its thickness is relatively thin, which can actively separate the particles into interlayers. It exhibits inertness before and after doping, meaning it does not react with the thermal storage matrix material and does not affect its active thermal storage / release process.

[0037] This embodiment describes a method for preparing a high-temperature thermochemical thermal storage material with anti-sintering properties based on a sandwiched particle structure, including the following steps:

[0038] Step 1: Determine the amount of lamellar inert dopant to be added based on the degree of sintering of the granular thermal storage functional matrix material during conventional thermal storage / release.

[0039] The porosity of the material formed by the magnesium hydroxide particles used in this embodiment during the conventional 120-450℃ heat storage process was detected by the BET method. Specifically, the magnesium hydroxide particles were placed in a reactor and heated to 400℃ at a rate of 10℃ / min. After holding at this temperature for 30 min, the material was removed and its porosity was measured. The degree of sintering of the particulate heat storage functional matrix material was defined by the porosity state.

[0040] When sintering causes the porosity to be below 50%, it is defined as an over-burned state, in which the doping amount of the lamellar inert doped material is 8-10 wt%. When sintering causes the porosity to be 50-70%, it is defined as an under-burned state, in which the doping amount of the lamellar inert doped material is 4-6 wt%. When the porosity is 70%-90%, it is defined as a normal state, in which the doping amount of the lamellar inert doped material is 1-2 wt%.

[0041] In this embodiment, the doping amount of the CaTiO3 powder sheet material is determined to be 2 wt%.

[0042] Step 2: Add flaky inert dopant to the granular thermal storage matrix material at a doping amount of 2wt%. Add CaTiO3 powder flaky material to the magnesium hydroxide particles. Perform low-frequency ultrasonic dispersion treatment on the mixture at an ultrasonic frequency of 15KHz and mix thoroughly for 10min. This allows the flaky inert dopant to be dispersed layer by layer in the granular thermal storage matrix material. The granular thermal storage matrix material is then spaced layer by layer to form a multi-layer sandwich granular structure anti-sintering high-temperature thermochemical thermal storage material.

[0043] In this embodiment, magnesium hydroxide particles no longer exhibit the traditional particle stacking pattern. After doping with CaTiO3 powder flakes, the magnesium hydroxide particles are uniformly separated by low-frequency ultrasound, forming random interlayers with various thin-film structures. The CaTiO3 powder flakes are inert materials, and because they do not react with the matrix, they do not affect the forward or reverse process of thermochemical heat storage, thus maintaining the original equilibrium state.

[0044] Example 2

[0045] This embodiment provides a high-temperature thermochemical thermal storage material based on a sandwich particle structure that prevents sintering and its preparation method.

[0046] In this embodiment, the granular thermal storage matrix material is magnesium hydroxide particles with a particle size of 100–200 nm. The thermal storage and release processes are achieved through the transformation between magnesium oxide and magnesium hydroxide, exhibiting a relatively stable pressure and temperature change process. The sheet-like inert dopant material is CaTiO3 powder sheet material with a particle size of 500–1000 nm and a thickness of 10–20 nm. The equivalent size of the CaTiO3 powder sheet material is significantly larger than the particle diameter, and its thickness is relatively thin, which can actively separate the particles into interlayers. It exhibits inertness before and after doping, meaning it does not react with the thermal storage matrix material and does not affect its active thermal storage / release process.

[0047] This embodiment describes a method for preparing a high-temperature thermochemical thermal storage material with anti-sintering properties based on a sandwiched particle structure, including the following steps:

[0048] Step 1: Determine the amount of lamellar inert dopant to be added based on the degree of sintering of the granular thermal storage functional matrix material during conventional thermal storage / release.

[0049] The porosity of the material formed by the magnesium hydroxide particles used in this embodiment during the conventional 120-450℃ heat storage process was detected by the BET method. Specifically, the magnesium hydroxide particles were placed in a reactor and heated to 400℃ at a rate of 10℃ / min. After holding at this temperature for 30 min, the material was removed and its porosity was measured. The degree of sintering of the granular heat storage functional matrix material was defined by the porosity state.

[0050] When sintering causes the porosity to be below 50%, it is defined as an over-burned state, in which the doping amount of the lamellar inert doped material is 8-10 wt%. When sintering causes the porosity to be 50-70%, it is defined as an under-burned state, in which the doping amount of the lamellar inert doped material is 4-6 wt%. When the porosity is 70%-90%, it is defined as a normal state, in which the doping amount of the lamellar inert doped material is 1-2 wt%.

[0051] In this embodiment, the doping amount of CaTiO3 powder flake material is determined to be 6 wt%.

[0052] Step 2: Add sheet-like inert dopant to the granular thermal storage matrix material at a doping amount of 6wt%. Add CaTiO3 powder sheet-like material to the magnesium hydroxide particles. Perform low-frequency ultrasonic dispersion treatment on the mixture at an ultrasonic frequency of 15KHz and mix thoroughly for 10min. This allows the sheet-like inert dopant to be dispersed layer by layer in the granular thermal storage matrix material. The granular thermal storage matrix material is then spaced layer by layer to form a multi-layer sandwich particle structure of anti-sintering high-temperature thermochemical thermal storage material.

[0053] The thermochemical thermal storage material prepared in this embodiment can be encapsulated in a container to carry out a complete thermal storage / release process, or it can be presented in bulk for structural characterization or thermal performance testing in a trace state.

[0054] Example 3

[0055] This embodiment provides a high-temperature thermochemical thermal storage material based on a sandwich particle structure that prevents sintering and its preparation method.

[0056] In this embodiment, the granular thermal storage matrix material is magnesium hydroxide particles with a particle size of 100–200 nm. The thermal storage and release processes are achieved through the transformation between magnesium oxide and magnesium hydroxide, exhibiting a relatively stable pressure and temperature change process. The sheet-like inert dopant material is CaTiO3 powder sheet material with a particle size of 500–1000 nm and a thickness of 10–20 nm. The equivalent size of the CaTiO3 powder sheet material is significantly larger than the particle diameter, and its thickness is relatively thin, which can actively separate the particles into interlayers. It exhibits inertness before and after doping, meaning it does not react with the thermal storage matrix material and does not affect its active thermal storage / release process.

[0057] This embodiment describes a method for preparing a high-temperature thermochemical thermal storage material with anti-sintering properties based on a sandwiched particle structure, including the following steps:

[0058] Step 1: Determine the amount of lamellar inert dopant to be added based on the degree of sintering of the granular thermal storage functional matrix material during conventional thermal storage / release.

[0059] The magnesium hydroxide particles used in this embodiment were tested using the BET method at a standard temperature of 120- ～ The porosity of the material formed during the 450℃ heat storage process; specifically, magnesium hydroxide particles are placed in a reactor and heated to 400℃ at a rate of 10℃ / min, held for 30min, and then the material is taken out and its porosity is measured; the degree of sintering of the granular heat storage functional matrix material is defined by the porosity state.

[0060] When sintering causes the porosity to be below 50%, it is defined as an over-burned state, in which the doping amount of the lamellar inert doped material is 8-10 wt%. When sintering causes the porosity to be 50-70%, it is defined as an under-burned state, in which the doping amount of the lamellar inert doped material is 4-6 wt%. When the porosity is 70%-90%, it is defined as a normal state, in which the doping amount of the lamellar inert doped material is 1-2 wt%.

[0061] In this embodiment, the doping amount of the CaTiO3 powder sheet material is determined to be 10 wt%.

[0062] Step 2: Add sheet-like inert dopant to the granular thermal storage matrix material at a doping amount of 10wt%. Add CaTiO3 powder sheet-like material to the magnesium hydroxide particles. Perform low-frequency ultrasonic dispersion treatment on the mixture at an ultrasonic frequency of 15KHz and mix thoroughly for 10min. This allows the sheet-like inert dopant to be dispersed layer by layer in the granular thermal storage matrix material. The granular thermal storage matrix material is then spaced layer by layer to form a multi-layer sandwich granular structure anti-sintering high-temperature thermochemical thermal storage material.

[0063] Comparative Example 1

[0064] This comparative example provides a thermochemical thermal storage material based on a sandwich particle structure and its preparation method.

[0065] In this comparative example, the particulate thermal storage functional matrix material is magnesium hydroxide particles with a particle size of 100-200 nm, and the sheet-like inert dopant material is CaTiO3 powder sheet material with a particle size of 500-1000 nm and a thickness of 10-20 nm.

[0066] The preparation method of the anti-sintering high-temperature thermochemical thermal storage material based on the sandwich particle structure in this comparative example is as follows: CaTiO3 powder flake material is added to magnesium hydroxide particles at a doping amount of 20wt%, and the mixture is subjected to low-frequency ultrasonic dispersion treatment at an ultrasonic frequency of 15KHz. After being fully mixed for 10min, the thermochemical thermal storage material based on the sandwich particle structure is obtained.

[0067] Comparative Example 2

[0068] This comparative example provides a thermochemical thermal storage material based on a sandwich particle structure and its preparation method.

[0069] In this comparative example, the particulate thermal storage functional matrix material is magnesium hydroxide particles with a particle size of 100-200 nm, and the sheet-like inert dopant material is CaTiO3 powder sheet material with a particle size of 500-1000 nm and a thickness of 10-20 nm.

[0070] The preparation method of the anti-sintering high-temperature thermochemical thermal storage material based on the sandwich particle structure in this comparative example is as follows: CaTiO3 powder flake material is added to magnesium hydroxide particles at a doping amount of 30wt%, and the mixture is subjected to low-frequency ultrasonic dispersion treatment at an ultrasonic frequency of 15KHz. After being fully mixed for 10min, the thermochemical thermal storage material based on the sandwich particle structure is obtained.

[0071] I. Structural characterization of the anti-sintering high-temperature thermochemical heat storage material and magnesium hydroxide particles prepared in Example 2.

[0072] The dispersion state of the anti-sintering high-temperature thermochemical heat storage material prepared in Example 2 was observed using a high-vacuum scanning electron microscope. The obtained scanning state is as follows: Figure 2 As shown in the figure, 401 is CaTiO3 powder flake material, 402 is magnesium hydroxide particles, and 403 is the sandwich particle structure observed under an electron microscope.

[0073] microstructure Figure 3 and 4 The distribution of pure magnesium hydroxide particles before and after high-temperature decomposition is shown. As can be seen from the figure, magnesium hydroxide calcined at high temperature in a steam atmosphere forms aggregates from individual particles, increasing particle size. These aggregated particles, due to deteriorated thermal conductivity, hinder the heat absorption and release processes of the material, thus affecting heat storage and release. Figure 5 and 6In this study, calcium titanate is a type of sheet-like particle with a certain thickness, and its particle size is significantly larger than that of magnesium hydroxide. After doping and dispersion, the magnesium hydroxide material, used for heat storage, adheres to the surface of the calcium titanate, uniformly isolating the stacked material particles within a spatial range. This is beneficial for the absorption and release of heat during the heat storage and release processes. Comparatively, 6% calcium titanate can serve as an ideal target sample, preventing material agglomeration and even improving the material's thermal conductivity and thermal properties.

[0074] Figure 9 This diagram illustrates the sintering process of magnesium hydroxide particles in a steam atmosphere. 301 represents magnesium atoms, 302 oxygen atoms, 303 hydrogen atoms, 304 water molecules, and 305 the sintered agglomerate. The surface of Mg(OH)₂ contains numerous acidic hydrophilic hydroxyl groups, and the surface hydrogen atoms are in an electron-deficient state, which readily forms hydrogen bonds to increase the stability of the molecular system. After the Mg(OH)₂ powder particles are stacked in the reactor, the outer surface of the particles exhibits an electron-positive state. This attracts a large number of water molecules in the steam atmosphere, manifesting microscopically as the overlapping of Mg(OH)₂ molecules and macroscopically as particle agglomeration, as shown in 305. At high temperatures, macroscopic sintering quickly occurs, destroying the material's superior properties.

[0075] II. Thermal performance tests were conducted on the thermochemical thermal storage materials prepared in Examples 1-3 and Comparative Examples 1-2.

[0076] The thermochemical thermal storage materials prepared in Examples 1-3 and Comparative Examples 1-2 were subjected to DSC tests using a comprehensive calorimeter to obtain decomposition curves and heat flow data. Decomposition state and enthalpy analysis were performed, and the results are shown in Table 1.

[0077] Table 1

[0078]

[0079] As shown in Table 1, the samples with different proportions of calcium titanate exhibit varying characteristics. Adding 2 wt% and 6 wt% of thermochemical thermal storage material resulted in an increase in enthalpy, reaching 978.5 J / g and 971.4 J / g, respectively. Adding 10 wt%, 20 wt%, and 30 wt% of the thermochemical thermal storage material reduced the enthalpy by 9.03%, 13.96%, and 30.5%, respectively.

[0080] When considering the doping amount of lamellar inert dopant, the proportion of additives can be appropriately increased based on the severity of sintering in granular thermal storage matrix materials. However, based on current test results using magnesium hydroxide as the experimental material, adding 6 wt% CaTiO3 powder lamellar material has a good mitigation effect when the porosity decreases to 50%. In extreme cases, to reduce the degree of sintering, increasing the doping amount of lamellar inert dopant and appropriately weakening the thermal storage capacity is within acceptable limits; a decrease in enthalpy of the thermal storage material of less than 10% is also acceptable.

[0081] Figure 7 The graphs show a comparison of the residual mass ratio and heat flow curves of magnesium hydroxide particles and the anti-sintering high-temperature thermochemical thermal storage material prepared in Example 2, as measured by a comprehensive calorimeter. These represent the heat absorption conditions during the thermal storage process. Overall, the anti-sintering high-temperature thermochemical thermal storage material prepared in Example 2 completed its thermal storage at 420℃, with the maximum heat flow occurring between 370 and 380℃, indicating the fastest heat absorption. The sample with added CaTiO3 powder flake material showed a significantly earlier thermal storage start and end point. This is because the granular thermal storage matrix material no longer accumulates, resulting in a smoother heat transfer process and optimized overall heat transfer.

[0082] Figure 8 The graph compares the enthalpy of magnesium hydroxide particles and the anti-sintering high-temperature thermochemical thermal storage material prepared in Example 2, as well as the residual mass ratio after thermal storage. It can be seen that, because the doped CaTiO3 powder flakes are inert and do not participate in thermal storage, the final residual mass of the anti-sintering high-temperature thermochemical thermal storage material prepared in Example 2 (72.96%) is higher than that of pure magnesium hydroxide (69.05%). However, the addition of CaTiO3 powder flakes optimizes the heat transfer path, significantly improving the thermal conductivity of the thermal storage material. This allows for the smooth introduction and removal of heat during the thermal storage / exothermic reaction process, enabling timely application of heat during the heat exchange process. This is reflected in the characterization test, where the energy storage density of the anti-sintering high-temperature thermochemical thermal storage material prepared in Example 2 reaches 971.4 J / g, compared to the energy storage density of 904 J / g for pure magnesium hydroxide particles.

[0083] The above demonstrates that the anti-sintering high-temperature thermochemical thermal storage material based on a sandwiched particle structure provided by this invention can achieve the purpose of anti-sintering through a simple preparation process. Furthermore, due to the sandwiched design of the particle structure, the particle packing form is optimized, improving both thermal conductivity and heat transfer. In particular, characterization shows a significant increase in the material's test enthalpy, enhancing the high-density thermal storage potential and applicability of the thermochemical thermal storage material, demonstrating high innovation and breakthrough. Thermochemical thermal storage technology is one of the important energy storage technologies, playing a crucial role in achieving energy conservation, emission reduction, and green carbon reduction policies in multiple fields, and has high promotional value.

Claims

1. A high-temperature thermochemical thermal storage material based on a sandwiched particle structure to prevent sintering, characterized in that, The material comprises a granular thermal storage functional matrix material and a sheet-like inert doped material. The sheet-like inert doped material is dispersed layer by layer in the granular thermal storage functional matrix material, and the granular thermal storage functional matrix material is spaced apart layer by layer to form a multi-layer sandwich particle structure to prevent sintering of the high-temperature thermochemical thermal storage material. The doping amount of the sheet-like inert doped material is 1 to 10 wt%, the particle size of the granular thermal storage functional matrix material is 100 to 200 nm, and the particle size of the sheet-like inert doped material is 500 to 1000 nm and the thickness is 10 to 20 nm.

2. The anti-sintering high-temperature thermochemical thermal storage material based on a sandwiched particle structure according to claim 1, characterized in that, The granular thermal storage matrix material includes one or a combination of several of the following: metal oxide / hydroxide particles, metal oxide / carbonate particles, multi-component oxide particles, or metal hydride particles; the metal oxide / hydroxide particles include CaO / Ca(OH)2 particles, MgO / Mg(OH)2 particles, or Al2O3 / Al(OH)3 particles; the metal oxide / carbonate particles include CaO / CaCO3 particles, MgO / MgCO3 particles, PbO / PbCO3 particles, or SrO / SrCO3 particles; the multi-component oxide particles include FeO / Fe2O3 particles, BaO / BaO2 particles, CoO / Co3O4 particles, or Mn3O4 / Mn2O3 particles; and the metal hydride particles include MgH / Mg particles or AlH / Al particles.

3. The anti-sintering high-temperature thermochemical thermal storage material based on a sandwiched particle structure according to claim 1, characterized in that, The sheet-like inert doped material includes coated sheet material, powdered sheet material, nanosheet material, metal sheet material, or ceramic sheet material; the coated sheet material includes ZnO or zinc-based chromium salt; the powdered sheet material includes CaTiO3 or MgCl2; the nanosheet material includes graphene or nano LiCoO2; the metal sheet material includes sheet-like nickel powder or zinc-aluminum alloy; and the ceramic sheet material includes Al2O3 or AlN.

4. A method for preparing a high-temperature thermochemical thermal storage material based on a sandwiched particle structure to prevent sintering, as described in any one of claims 1-3, characterized in that, Includes the following steps: Step 1: Determine the amount of lamellar inert dopant to be added based on the degree of sintering of the granular thermal storage functional matrix material during conventional thermal storage / release. Step 2: Add sheet-like inert dopant to the granular thermal storage matrix material and fully mix it by low-frequency ultrasonic dispersion to form a uniform multilayer sandwich particle structure.

5. The preparation method of a high-temperature thermochemical thermal storage material based on a sandwiched particle structure for preventing sintering according to claim 4, characterized in that, The degree of sintering of granular thermal storage matrix materials is defined by their porosity. When sintering causes the porosity to be below 50%, it is defined as an over-sintered state, in which the doping amount of the lamellar inert doped material is 8-10 wt%. When sintering causes the porosity to be 50-70%, it is defined as an under-sintered state, in which the doping amount of the lamellar inert doped material is 4-6 wt%. When the porosity is 70%-90%, it is defined as a normal state, in which the doping amount of the lamellar inert doped material is 1-2 wt%.

6. The method for preparing a high-temperature thermochemical thermal storage material based on a sandwiched particle structure to prevent sintering, as described in claim 4 or 5, is characterized in that... The low-frequency ultrasonic dispersion has an ultrasonic frequency of 10–20 kHz and an ultrasonic dispersion time of 5–10 min.

7. The application of a high-temperature thermochemical thermal storage material based on a sandwich particle structure as described in any one of claims 1-3 in seasonal thermal storage and long-distance heat transfer.

8. The application of the anti-sintering high-temperature thermochemical thermal storage material based on sandwich particle structure according to claim 7 in seasonal thermal storage and long-distance heat transfer, characterized in that, The heat storage / heat release temperature range of the medium-high temperature thermochemical heat storage material is 150–700℃, of which the medium temperature range is 150–350℃ and the high temperature range is 350–700℃.

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