Mixed nanometer ternary carbonate molten salt material for high-temperature heat storage and preparation method thereof

Abstract

The invention belongs to the technical field of heat storage materials, and particularly relates to a mixed nano fused salt material suitable for a high-temperature working condition as well as a preparation method and application of the mixed nano fused salt material. The mixed nano molten salt material is prepared by taking ternary carbonate composed of lithium carbonate, sodium carbonate and potassium carbonate as a matrix and introducing at least one kind of nano particles or a composite system of multiple kinds of nano particles, and the nano particles are selected from metal oxides, metal carbides, metal nitrides or carbon-based nano materials. The microstructure and interface characteristics of the ternary carbonate fused salt are regulated and controlled through the high specific surface area and the interface synergistic effect of the nano-particles, so that the specific heat capacity, the heat-conducting property and the photo-thermal conversion capacity of the ternary carbonate fused salt are remarkably improved, and the high-temperature cycling stability of the ternary carbonate fused salt is improved. According to the mixed nano fused salt material, on the premise that the original working temperature interval is basically unchanged, synergistic enhancement of multiple thermophysical properties is achieved, and the mixed nano fused salt material has excellent heat absorption and storage performance and long-term operation stability. The preparation method is simple in process and high in repeatability, and the obtained mixed nano fused salt material is suitable for integrated application of high-temperature heat storage and heat absorption in a concentrating solar power generation system and has a good engineering application prospect.

Description

Technical Field

[0001] This invention belongs to the field of thermal storage materials technology, and relates to a mixed nano-ternary carbonate molten salt material for high-temperature thermal storage and its preparation method. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] Molten salt, due to its excellent thermal stability, high specific heat capacity, and wide liquidus temperature range, has become the most promising thermal storage medium for concentrated solar power (CSP) systems. The operating temperature of the thermal storage medium directly affects the thermal cycle efficiency of the CSP power plant. Therefore, developing high-temperature molten salt thermal storage technology is an important direction for promoting CSP technology towards the fourth generation.

[0004] Currently, carbonates possess higher specific heat capacity and excellent high-temperature stability, performing better in applications above 600 °C, and are considered potential candidates for next-generation high-temperature CSP (Continuous Storage Power Supply) materials. However, single carbonates (such as Na₂CO₃, K₂CO₃, and Li₂CO₃) generally suffer from high melting points, leading to increased system start-up and shutdown temperatures and greater insulation losses, thus limiting their practical engineering applications. To overcome the drawback of excessively high melting points of single carbonates, academia and industry generally adopt eutectic design strategies, lowering the melting temperature by adjusting the ratio between different carbonates. In this direction, ternary carbonate systems (such as Li₂CO₃-Na₂CO₃-K₂CO₃) have gradually become a research focus due to their combination of lower eutectic points, wider operating temperature windows, and good thermal stability, demonstrating significant advantages in high-temperature thermal storage applications.

[0005] Although ternary carbonate systems demonstrate outstanding performance in high-temperature thermal storage, they still face challenges such as low thermal conductivity, limited potential for increasing specific heat capacity, and low photothermal conversion efficiency. Insufficient thermal conductivity limits the system's heat charge and release rates, while low specific heat capacity necessitates larger storage tank volumes to meet energy storage requirements, thus impacting overall efficiency and economics. Furthermore, low photothermal conversion efficiency leads to insufficient solar energy absorption, preventing the molten salt from acquiring enough heat per unit time. This not only reduces heat collection efficiency but also increases system energy loss, affecting thermal storage performance and power generation efficiency under high-temperature operation.

[0006] To address this, some studies have introduced high thermal conductivity SiC nanoparticles into the Li2CO3-Na2CO3-K2CO3 ternary system to create high-temperature thermal storage materials, but their specific heat capacity and thermal conductivity still need to be improved. Summary of the Invention

[0007] To address the aforementioned problems, this invention provides a hybrid nano-molten salt material for high-temperature thermal storage, its preparation method, and its application, aiming to solve the problems commonly found in existing ternary carbonate molten salt systems, such as low thermal conductivity, limited specific heat capacity improvement, and insufficient photothermal conversion rate.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a mixed nano-ternary carbonate molten salt material for high-temperature heat storage, which is composed of ternary carbonate and nanoparticles; The ternary carbonate is composed of Li2CO3, Na2CO3 and K2CO3; The nanoparticles are TiN or TiN-SiC mixed nanoparticles, and the amount used is 1wt%-3wt% of ternary carbonate.

[0009] A second aspect of the present invention provides a method for preparing a mixed nano-ternary carbonate molten salt material for high-temperature thermal storage, comprising: Li2CO3, Na2CO3, and K2CO3 are mixed evenly in a solution to obtain a ternary carbonate solution; Nanoparticles were added to the ternary carbonate solution and dispersed under heating and ultrasonic conditions to obtain a nanoparticle-molten salt suspension. The nanoparticle-molten salt suspension was dried to obtain a solid precursor. The solid precursor is ground until homogeneous to obtain the final product.

[0010] A third aspect of the present invention provides the application of the above-mentioned mixed nano-ternary carbonate molten salt material or the mixed nano-ternary carbonate molten salt material prepared by the above-mentioned method in high-temperature thermal storage systems, especially in concentrated solar power (CSP) systems, as a direct heat absorption and thermal storage integrated medium to improve the specific heat capacity, thermal conductivity, light absorption capacity, photothermal conversion efficiency and high-temperature cycling stability of the thermal storage medium.

[0011] Beneficial effects of the present invention (1) The melting point is lowered and the decomposition temperature is increased, which significantly enhances the safety and stability of the system operation.

[0012] The high-temperature ternary mixed carbonate-based nano-molten salt material prepared by this invention has a low melting point (388–399 °C) and a high decomposition temperature (837–842 °C). Compared with traditional high-melting-point carbonate-based thermal storage materials, this material can effectively reduce the start-up temperature and insulation requirements of solar thermal power generation systems, reduce the risk of pipeline blockage caused by molten salt crystallization, and reduce dependence on external auxiliary heating systems, thereby significantly improving the safety, reliability, and economy of heat transfer and thermal storage systems.

[0013] (2) The specific heat capacity and thermal conductivity are significantly improved, and the heat transfer and heat storage capacity are significantly enhanced.

[0014] Through the interfacial structure regulation and synergistic enhancement of nanoparticles, the specific heat capacity and thermal conductivity of the high-temperature ternary mixed carbonate-based nanomolten salt material prepared in this invention are simultaneously improved. Compared with undoped ternary carbonate molten salt, the specific heat capacity is increased by approximately 10.8%-40.9%, and the thermal conductivity is increased by approximately 24.6%-106.1%, significantly enhancing the material's energy storage density and thermal response speed, making it more suitable for rapid charge-discharge heat dissipation applications under high-temperature conditions.

[0015] (3) The photothermal conversion performance is greatly improved and the solar energy absorption capacity is significantly enhanced.

[0016] The high-temperature ternary mixed carbonate-based nano-molten salt material prepared by this invention exhibits higher optical absorption capacity within the solar spectrum, with an absorbance of up to 79.21%, which is 39.83% higher than that of the base salt. This enhanced photothermal conversion capability enables the material to convert solar radiation energy into heat energy more efficiently, thus combining heat absorption and heat storage functions in concentrated solar power generation systems, significantly improving the overall photothermal utilization efficiency of the system.

[0017] (4) It achieves synergistic improvement of multiple thermophysical properties within the high-temperature working window, and has excellent cycle stability and engineering application potential.

[0018] The high-temperature ternary mixed carbonate-based nano-molten salt material prepared by this invention, while maintaining the original ternary carbonate molten salt's operating temperature range essentially unchanged, achieves a specific heat capacity of up to approximately 2.36 J / (g·K), a thermal conductivity of up to approximately 1.34 W / (m·K), and a light absorption rate increase of up to 79.83% in the preferred embodiment through nanoparticle reinforcement and interfacial synergy. Furthermore, after 50 high-temperature cycle tests at temperatures ranging from room temperature to 750 °C, the material exhibits a mass loss of less than 0.5% and a specific heat capacity decrease of only about 5.6%, demonstrating excellent high-temperature cycling stability and long-term operational reliability.

[0019] Therefore, the high-temperature ternary mixed carbonate-based nanomolten salt material prepared by this invention achieves a synergistic improvement in key properties such as specific heat capacity, thermal conductivity and photothermal conversion capability without reducing high-temperature stability, and has significant engineering adaptability and practical application value. Attached Figure Description

[0020] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. Exemplary embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0021] Figure 1(a) Spectral absorption curves and (b) average light absorption rates of ternary carbonate molten salts doped with TiN, SiC, and TiN-SiC mixed nanoparticles. Figure 2 This is a schematic diagram of a centralized solar simulator system; Figure 3 The following are the (a) real-time photothermal temperature change curves of ternary carbonate molten salts doped with TiN, SiC, and TiN-SiC mixed nanoparticles under xenon lamp irradiation; and (b) stable heat storage temperature and average heating rate. Figure 4 The mass change curves of ternary carbonate molten salts doped with TiN, SiC, and TiN–SiC mixed nanoparticles during high-temperature cycling are shown. Figure 5 The curves show the specific heat capacity of ternary carbonate molten salts doped with TiN, SiC, and TiN–SiC mixed nanoparticles as a function of the number of cycles during high-temperature cycling. Detailed Implementation

[0022] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of skill in the art. The reagents and raw materials used in this invention are readily available through conventional means, and unless otherwise specified, they are used in accordance with conventional methods in the art or product instructions. Similarly, unless otherwise specified, the test methods of this invention are performed in accordance with conventional methods in the art or industry-standard methods or practices. Furthermore, any methods and materials similar to or equivalent to those described herein may be applied to the methods of this invention. The preferred embodiments and materials described herein are for illustrative purposes only.

[0024] As described in the background section, in order to address the problems commonly found in existing ternary carbonate molten salt systems, such as low thermal conductivity, limited specific heat capacity improvement, and insufficient photothermal conversion efficiency, this invention provides a hybrid nano-ternary carbonate molten salt material for high-temperature thermal storage, composed of ternary carbonates and nanoparticles; The ternary carbonate is composed of Li2CO3, Na2CO3 and K2CO3; The nanoparticles are TiN or TiN-SiC mixed nanoparticles, and the amount used is 1wt%-3wt% of ternary carbonate.

[0025] This invention introduces at least one nanoparticle or a composite system of multiple nanoparticles into a Li2CO3–Na2CO3–K2CO3 ternary carbonate matrix. By utilizing the extremely high surface activity and interfacial effect of the nanoparticles, the microstructure and interfacial properties of the molten salt are controlled, thereby achieving a synergistic improvement in the specific heat capacity, thermal conductivity and photothermal conversion performance of the ternary carbonate molten salt.

[0026] The nanoparticles of the present invention are selected from one or more of metal nitrides or carbon-based nanomaterials. Preferably, the nanoparticles have a particle size of 10–60 nm and are incorporated into a ternary carbonate matrix in an effective amount that can enhance thermal properties.

[0027] The ratio of Li2CO3, Na2CO3 and K2CO3 affects the thermal properties of molten salt. Therefore, this invention studies the mass ratio of Li2CO3, Na2CO3 and K2CO3. Preferably, they are prepared in a near-eutectic ratio, with the mass ratio of Li2CO3, Na2CO3 and K2CO3 being 4:4:2-2.5. More preferably, it is 4:4:2 to obtain better thermal properties.

[0028] Compared with the addition of TiN and SiC nanoparticles alone, TiN-SiC has a synergistic effect in enhancing the specific heat capacity of molten salt, thermal conductivity, light absorption capacity, photothermal conversion efficiency and high-temperature cycling stability. Preferably, the mass ratio of TiN to SiC in the TiN-SiC mixed nanoparticles is 1:1-1.5, and more preferably, it is 1:1, so as to obtain a better enhancement effect.

[0029] This invention provides a method for preparing a mixed nano-ternary carbonate molten salt material for high-temperature thermal storage, comprising: Li2CO3, Na2CO3, and K2CO3 are mixed evenly in a solution to obtain a ternary carbonate solution; Nanoparticles were added to the ternary carbonate solution and dispersed under heating and ultrasonic conditions to obtain a nanoparticle-molten salt suspension. The nanoparticle-molten salt suspension was dried to obtain a solid precursor. The solid precursor is ground until homogeneous to obtain the final product.

[0030] This invention combines liquid-phase dispersion with physical field-assisted methods to achieve uniform distribution and stable anchoring of nanoparticles in a ternary carbonate matrix, thereby forming a nanocomposite molten salt material with good structural stability and interfacial synergistic effects. The preferred preparation method includes steps such as carbonate dissolution, nanoparticle dispersion, drying and crystallization, and grinding.

[0031] To ensure uniform mixing of the solutions in the solvent, the present invention investigated the mixing temperature and time. Preferably, the mixing conditions are stirring at 20-25 °C for 1-1.5 h to ensure that each molten salt is effectively dissolved in the water.

[0032] To achieve uniform distribution and stable anchoring of nanoparticles in a ternary carbonate matrix, this invention employs auxiliary treatments of heating and ultrasonic dispersion. Preferably, the ultrasonic power is 45-50 kHz, and the heating is carried out at 50-60 ℃, to form a nanocomposite molten salt material with good structural stability and interfacial synergistic effect.

[0033] This invention does not impose any special limitation on the drying temperature, as long as all moisture is removed. To ensure the drying effect, it is preferable to dry at 80-120 ℃ for 12-14 h to improve the drying efficiency.

[0034] The present invention will be further described in detail below with reference to specific embodiments. It should be noted that the specific embodiments are explanations of the present invention and not limitations thereof.

[0035] This invention provides a series of mixed nano-molten salt formulations for high-temperature thermal storage in CSP (Continuous Storage Power) systems. These formulations are primarily composed of ternary carbonate molten salt and nanoparticles. The ternary carbonate molten salt consists of potassium carbonate, lithium carbonate, and sodium carbonate, with the following mass percentages: 40 wt% potassium carbonate, 40 wt% lithium carbonate, and 20 wt% sodium carbonate. The nanoparticles are one or more of TiN, SiC, SiO2, Al2O3, CuO, C, and Fe2O3, with an average particle size of 10-60 nm. To ensure the comparability of the reinforcing effects of different nanoparticles, in the performance screening examples, the addition ratio of the nanoparticles is uniformly set to 1 wt% of the total mass of the mixed nano-molten salt.

[0036] I. A method for preparing novel mixed nano-ternary carbonate molten salt materials, comprising the following steps: (1) Preparation of ternary carbonate base salts Weigh out the three carbonates according to the mass ratio of Li2CO3:Na2CO3:K2CO3 = 4:4:2, add them to 300 mL of deionized water, and stir at 25 ℃ for 1 h to form a uniform and transparent ternary carbonate solution.

[0037] (2) Addition and dispersion of nanoparticles A set proportion of nanoparticles was added to the above solution, and the solution was treated under ultrasonic conditions of 60 °C and 45 kHz for 2 h to obtain a stable nanoparticle-molten salt suspension.

[0038] (3) Drying step The suspension was placed in an oven and dried at 120 °C for 14 h to remove all moisture and obtain a dry solid precursor.

[0039] (4) Grinding step The dried solid material is placed in a mortar and ground thoroughly until it becomes a uniform fine powder, thus obtaining a ternary carbonate composite molten salt material reinforced with mixed nanoparticles.

[0040] II. Performance Testing Methods The performance of the obtained samples was tested using the following method: 1. Melting point and decomposition temperature: DSC / TGA tests were used, with a mass loss exceeding 5% as the criterion for decomposition.

[0041] 2. Specific heat capacity: The average value of the liquid specific heat capacity within the temperature range of 450–550 ℃ was measured using DSC.

[0042] 3. Thermal conductivity: The thermal conductivity under liquid conditions at 500 °C was measured using a laser thermal conductivity meter.

[0043] 4. Spectral absorption performance: The test wavelength range is 300–2500 nm.

[0044] 5. Photothermal conversion test: A xenon lamp with an irradiance of 240 kW / m2 was used to simulate solar irradiation.

[0045] 6. High-temperature cycling stability: 50 heating-cooling cycles were performed in a muffle furnace at 25–750 °C.

[0046] Example 1: Screening of thermophysical properties of different nanoparticle types in 1 wt% ternary carbonate molten salt Using the above preparation method, various nanocomposite molten salt samples doped with TiN, SiC, SiO2, Al2O3, CuO, C, and Fe2O3 were prepared, with undoped ternary carbonate molten salt as a comparative example.

[0047] The test results of specific heat capacity, thermal conductivity, melting point and decomposition temperature of each sample are shown in Table 1.

[0048] Table 1. Effects of different nanoparticles at 1 wt% doping on the thermophysical properties of ternary carbonate molten salt

[0049] Analysis of the screening results, as shown in Table 1, reveals that compared to the undoped ternary carbonate-based salt (No. 9), the melting points of the high-temperature ternary mixed carbonate-based nanomolten salt materials No. 1-No. 8 prepared in this invention are slightly lower, the decomposition temperature is slightly higher, and the overall operating temperature window is wider.

[0050] Within the temperature range of 450–550 ℃, the average specific heat capacity of the ternary carbonate base salt is 1.66 J / (g·K), while the specific heat capacity of the nanocomposite molten salt samples is significantly improved, with an increase of approximately 10.8%–40.9%; at the same time, its thermal conductivity is improved by approximately 24.6%–106.1% compared to the base salt.

[0051] Among them, composite molten salts doped with TiN, SiC, and SiC–TiN nanoparticles exhibited the most significant synergistic enhancement effects in terms of specific heat capacity and thermal conductivity. Therefore, the above nanoparticle systems were selected as preferred enhancement systems for further research on viscosity, photothermal conversion performance, and high-temperature cycling stability.

[0052] Example 2: Test on the photothermal conversion performance and high-temperature cycling stability of ternary carbonate molten salt enhanced by preferred nanoparticles Based on the screening results of Example 1, SiC, TiN and SiC–TiN mixed nanoparticle-doped ternary carbonate molten salts (corresponding to samples No.2–No.4) that exhibited excellent performance in terms of specific heat capacity and thermal conductivity were selected as research objects, and their photothermal conversion performance and high-temperature cycling stability were further tested and analyzed.

[0053] 1. Spectral absorption performance test The optical absorption properties of the samples were measured using a Cary 5000 UV-Vis-NIR spectrophotometer (Agilent Technologies, USA), with a wavelength range of 300–2500 nm. The obtained spectral absorbance data were used to calculate the average light absorbance of the samples, as shown in the following formula:

[0054] in: A abs The average light absorbance of the sample is (%). λ ￠ For spectral wavelength (nm); A( λ ￠ ) is the sample at wavelength λ ￠ Spectral absorbance (%) at the following levels; I ( λ ￠ The value is the standard AM1.5G solar spectral irradiance, expressed in W / (m²·nm). The overall absorption capacity of the sample to the solar spectrum was obtained through the above tests.

[0055] like Figure 1As shown, compared with the undoped ternary carbonate molten salt base (No. 9), the novel nanocomposite molten salts No. 2–No. 4 prepared in this invention exhibit significantly enhanced light absorption capacity, with average absorbance increases of approximately 25.9%, 36.8%, and 39.8%, respectively. The results indicate that the introduction of TiN and SiC nanoparticles can effectively improve the absorption capacity of ternary carbonate molten salts for solar radiation, with the mixed nanoparticle system exhibiting a more significant synergistic enhancement effect.

[0056] 2. Photothermal conversion performance test: The actual photothermal conversion capability of the sample was tested using a xenon lamp solar irradiation simulation heating system, such as... Figure 2 As shown in the diagram, the testing system uses a xenon lamp (Shanghai Fude Lighting Equipment Co., Ltd.) to simulate solar irradiation. Before the test, the distance between the xenon lamp and the heat-insulating test platform was adjusted by adjusting the fixed pulleys on the support to stabilize the light irradiance received by the sample surface at 240 kW / m². During the test, approximately 10 g of sample was placed in the heat-insulating platform, and a thermocouple was inserted 3 cm below the sample surface to measure the internal temperature change. The temperature acquisition system recorded the photothermal heating process of the sample in real time.

[0057] The photothermal heating rate of the sample ( TR Calculate using the following formula:

[0058] in: T p The real-time temperature (°C) of the sample during the photothermal test; t p For the corresponding time (s).

[0059] In addition, the stable photothermal temperature reached by the sample under xenon lamp irradiation was recorded. Ts (), used to evaluate the final heat storage capacity of materials under continuous light and heat input.

[0060] like Figure 3 As shown, the undoped ternary carbonate molten salt base (No. 9) exhibits a photothermal heating rate of approximately 9.15 °C / s and a stable photothermal temperature of approximately 650 °C. In contrast, the photothermal heating rates of the nanocomposite molten salts No. 2–No. 4 prepared in this invention are significantly improved, increasing by approximately 66.8%, 79.1%, and 102.3%, respectively, and their stable photothermal temperatures are also significantly higher. These results indicate that doping with TiN, SiC, and SiC–TiN composite nanoparticles can significantly improve the photothermal conversion efficiency and high-temperature heat storage capacity of ternary carbonate molten salts.

[0061] 3. High-temperature cycling stability test: The high-temperature cycling stability of the samples was tested using a gravimetric method. The molten salt samples were placed in nickel crucibles and then placed in a muffle furnace. The temperature was raised from room temperature to 750 °C and held for 2 hours, followed by natural cooling to room temperature. The samples were then weighed using an analytical balance. This heating-cooling process constituted one complete thermal cycle, and the rate of mass change after each cycle was recorded, along with the change in specific heat capacity.

[0062] Ternary carbonate molten salt samples doped with TiN, SiC, and SiC–TiN mixed nanoparticles were subjected to 50 high-temperature cycles, and the test results are shown in Figures 3 and 4.

[0063] Depend on Figure 3 It can be seen that after 50 high-temperature cycles, the mass loss of the ternary carbonate molten salt base salt is about 0.48%, while the mass loss of the nanocomposite molten salts No.2–No.4 prepared in this invention is lower than that of the base salt, indicating that they have better high-temperature thermal stability and can achieve stable operation at 750 ℃.

[0064] Depend on Figure 4 It is known that the specific heat capacity of the ternary carbonate molten salt base salt decreases by about 4.8% after 50 thermal cycles. Although the specific heat capacity of the nanocomposite molten salts No.2–No.4 prepared in this invention also decreases to some extent during the cycling process, their specific heat capacity after cycling is still significantly higher than that of the ternary carbonate molten salt base salt. This indicates that the nanocomposite molten salt material still maintains a high heat storage capacity under high-temperature cycling conditions and has good potential for engineering applications.

[0065] In summary, the hybrid nano-ternary carbonate molten salt material prepared by this invention significantly improves the material's light absorption capacity, photothermal conversion efficiency, and high-temperature cycling stability by enhancing and synergistically enhancing it through TiN, SiC, and SiC–TiN composite nanoparticles while maintaining the original operating temperature window. This material has a simple preparation method, a wide applicable temperature range, and excellent heat transfer, heat storage, and photothermal properties, making it suitable for integrated high-temperature heat storage and absorption applications in concentrated solar power generation systems.

[0066] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A mixed nano-ternary carbonate molten salt material for high-temperature heat storage, characterized in that, Composed of ternary carbonates and nanoparticles; The ternary carbonate is composed of Li2CO3, Na2CO3 and K2CO3; The nanoparticles are TiN or TiN-SiC mixed nanoparticles, and the amount used is 1wt%-3wt% of ternary carbonate.

2. The mixed nano-ternary carbonate molten salt material for high-temperature heat storage as described in claim 1, characterized in that, The nanoparticles have a particle size of 10–60 nm.

3. The mixed nano-ternary carbonate molten salt material for high-temperature thermal storage as described in claim 1, characterized in that, The mass ratio of Li2CO3, Na2CO3 and K2CO3 is 4:4:2-2.

5.

4. The mixed nano-ternary carbonate molten salt material for high-temperature thermal storage as described in claim 1, characterized in that, In the TiN-SiC mixed nanoparticles, the mass ratio of TiN-SiC is 1:1-1.

5.

5. A method for preparing a mixed nano-ternary carbonate molten salt material for high-temperature heat storage, characterized in that, include: Li2CO3, Na2CO3, and K2CO3 are mixed evenly in a solution to obtain a ternary carbonate solution; Nanoparticles were added to the ternary carbonate solution and dispersed under heating and ultrasonic conditions to obtain a nanoparticle-molten salt suspension. The nanoparticle-molten salt suspension was dried to obtain a solid precursor. The solid precursor is ground until homogeneous to obtain the final product.

6. The method for preparing the mixed nano-ternary carbonate molten salt material for high-temperature thermal storage as described in claim 5, characterized in that, The mixing conditions are stirring at 20-25℃ for 1-1.5 h.

7. The method for preparing the mixed nano-ternary carbonate molten salt material for high-temperature thermal storage as described in claim 5, characterized in that, The power of the ultrasound is 45-50 kHz.

8. The method for preparing the mixed nano-ternary carbonate molten salt material for high-temperature thermal storage as described in claim 5, characterized in that, Heat to 50-60 ℃.

9. The method for preparing the mixed nano-ternary carbonate molten salt material for high-temperature thermal storage as described in claim 5, characterized in that, Dry at 80-120 ℃ for 12-14 h.

10. The application of the mixed nano-ternary carbonate molten salt material according to any one of claims 1-4 or the mixed nano-ternary carbonate molten salt material prepared by the method according to any one of claims 5-9 in a high-temperature thermal storage system, characterized in that, The high-temperature thermal storage system includes a concentrated solar power generation system.

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