A low-melting-point molten salt energy storage material and its preparation method
By modifying silicon carbide nanowires and sheet-like zinc-aluminum flakes, a low-melting-point molten salt energy storage material was prepared. This solved the problems of easy solidification and limited operating temperature range of molten salt thermal storage and heat transfer materials, achieving higher stability and a wider temperature application range, reducing system costs and improving power generation efficiency.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SHANXI WOJIN NEW MATERIAL CO LTD
- Filing Date
- 2026-03-03
- Publication Date
- 2026-05-26
Smart Images
Figure SMS_1
Abstract
Description
Technical Field
[0001] This invention belongs to the field of physical heat transfer energy storage materials technology, specifically a low melting point molten salt energy storage material and its preparation method. Background Technology
[0002] Solar energy is one of the most economical and environmentally friendly renewable energy sources.
[0003] Currently, large-scale centralized utilization of solar energy mainly relies on solar power generation technology. There are two main types of solar power generation: photovoltaic (PV) power generation and concentrated solar power (CSP) power generation. PV power generation uses solar panels to directly convert sunlight into voltage and current, but it is greatly affected by sunlight conditions, especially cloudy days, nighttime, and rainy or snowy weather. CSP power generation, on the other hand, uses large solar panels to concentrate sunlight into heat energy at a single point, generating a very high temperature and a large amount of heat. This heat is then conducted away using heat transfer materials and passed through a steam generator to produce high-temperature, high-pressure steam. This steam then drives a turbine to generate electricity.
[0004] Solar thermal power generation equipment is designed with thermal storage units, filled with thermal storage materials to store the abundant solar energy during the day and continue generating electricity at night, on cloudy days, and during rainy or snowy periods. Therefore, solar thermal power generation technology is the mainstream for large-scale solar power generation applications in the future. After decades of technological research and accumulation, the cost of solar thermal power generation has been significantly reduced in recent years. To reduce costs, the thermal storage and heat transfer materials used in solar thermal power plants are generally the same material. Thermal storage and heat transfer technology is one of the three core technologies of solar thermal power plants, and its cost generally accounts for one-third of the total investment. Solar thermal power plants store thermal energy using sensible heat, that is, by cooling and raising the thermal storage material. Given a fixed specific heat capacity and mass of the thermal storage material, the greater the temperature range of the material, the more thermal energy it can store. This requires the thermal decomposition temperature of the thermal storage material to be as high as possible. The higher the thermal decomposition temperature of the material, the wider its applicable temperature range. Especially for solar thermal power plants, the thermal decomposition temperature of the thermal storage material determines the temperature of the generated steam, which directly affects the power generation efficiency of the steam turbine.
[0005] Thermal energy engineering, especially solar thermal power plants, requires heat storage and transfer fluids with a wide operating temperature range. Currently, the most common commercially available molten salt heat storage and transfer material is the solar salt mixed molten salt system, with an operating temperature range of 220-600℃. Its disadvantage is its relatively high melting point, which makes it prone to solidification during use, potentially clogging pipes and posing a safety hazard. Preventing this solidification hazard requires the installation of numerous additional temperature sensors and electric heating auxiliary equipment, significantly increasing project costs and subsequent maintenance and operating expenses. Summary of the Invention
[0006] The purpose of this invention is to provide a low-melting-point molten salt energy storage material and its preparation method. This method involves introducing modified silicon carbide nanowires and modified sheet-like zinc-aluminum flakes as functional fillers generated through a mercapto-olefin click reaction to composite modify a ternary nitrate molten salt. Compared with the unmodified basic molten salt system, the prepared low-melting-point molten salt energy storage material achieves comprehensive improvements in thermal performance, corrosion resistance, cycle stability, and physical structural stability. Its melting point is around 81-93℃, which is lower than that of SolarSalt. Compared with existing mixed molten salts, its melting point is reduced to varying degrees, greatly reducing the overall system cost, improving system safety and stability, obtaining a wider operating temperature range, and improving power generation efficiency.
[0007] The objective of this invention can be achieved through the following technical solutions:
[0008] A method for preparing a low-melting-point molten salt energy storage material includes the following steps:
[0009] Step 1: Using 3-mercaptopropyltrimethoxysilane as a modifier, the silanol groups generated by hydrolysis undergo a dehydration condensation reaction with the hydroxyl groups on the surface of silicon carbide nanowires to obtain modified silicon carbide nanowires.
[0010] Step 2: The flaky zinc-aluminum flakes are treated with γ-methacryloxypropyltrimethoxysilane to obtain modified flaky zinc-aluminum flakes.
[0011] Step 3: The modified silicon carbide nanowires and modified sheet-like zinc-aluminum flakes undergo a mercapto-olefin click reaction under the action of the photoinitiator 2,2-dimethylolpropionic acid to obtain the functional filler.
[0012] Step 4: Mix and grind potassium nitrate, sodium nitrate, calcium nitrate and functional filler, and stir evenly to obtain solid mixed molten salt.
[0013] Step 5: Dry the solid mixed molten salt and then calcine it to melt it, obtaining molten salt; cool the molten salt, crush it, and dry it again to obtain low melting point molten salt energy storage material.
[0014] Furthermore, the ratio of potassium nitrate, sodium nitrate, calcium nitrate, and functional filler is 500-520g: 150-155g: 350-357g: 7-9g.
[0015] Furthermore, the specific preparation steps for the modified silicon carbide nanowires are as follows:
[0016] Silicon carbide nanowires, 3-mercaptopropyltrimethoxysilane, anhydrous ethanol, and deionized water were added to a reaction vessel. The pH was adjusted to 3-4 with hydrochloric acid solution. The mixture was stirred for 22-24 hours at 20-25℃ and 500-600 r / min. After filtration, the precipitate was washed 3-4 times with deionized water and anhydrous ethanol and dried under vacuum at 60-80℃ for 1.6-1.8 hours to obtain modified silicon carbide nanowires.
[0017] Furthermore, the ratio of silicon carbide nanowires, 3-mercaptopropyltrimethoxysilane, anhydrous ethanol, and deionized water is 120-135g: 93-103mL: 300-333mL: 929-1028mL.
[0018] Furthermore, the specific preparation steps for the modified flaky zinc-aluminum flakes are as follows:
[0019] Add flaky zinc-aluminum flakes, γ-methacryloxypropyltrimethoxysilane, anhydrous ethanol, and deionized water to a reaction vessel, adjust the pH to 3.9-4.1 with hydrochloric acid solution, stir for 22-24 h at 20-25℃ and 500-600 r / min, filter, wash the precipitate 3-4 times with deionized water and anhydrous ethanol, and vacuum dry at 60-80℃ for 1.6-1.8 h to obtain modified flaky zinc-aluminum flakes.
[0020] Furthermore, the ratio of the amount of flaky zinc-aluminum flakes, γ-methacryloyloxypropyltrimethoxysilane, anhydrous ethanol, and deionized water is 115-135g: 85.1-96.3mL: 230-253mL: 825-978mL.
[0021] Furthermore, the specific preparation steps of the functional filler are as follows:
[0022] Modified silicon carbide nanowires, modified zinc-aluminum flakes, 2,2-dimethylolpropionic acid and tetrahydrofuran were added to a reaction vessel and stirred for 10-12 min at 20-25℃ and 500-600 r / min. Then, the mixture was reacted for 6-7 h at a wavelength of 365 nm and a light intensity of 6 mW / cm. After filtration, the precipitate was washed 2-4 times with deionized water and anhydrous ethanol, respectively, and then dried under vacuum at 60-70℃ for 1-2 h to obtain the functional filler.
[0023] Furthermore, the ratio of modified silicon carbide nanowires, modified sheet-like zinc-aluminum flakes, 2,2-dimethylolpropionic acid and tetrahydrofuran is 20-25g: 15-20g: 0.8-1g: 800-900mL.
[0024] Furthermore, the specific preparation steps for low-melting-point molten salt energy storage materials are as follows:
[0025] Solid mixed molten salt is placed in a constant temperature drying oven at 90-100℃ for 36-38 hours. The dried solid mixed molten salt is then placed in a muffle furnace and heated to 450-500℃ at a heating rate of 8-10K / min to melt the mixed molten salt. After standing for 18-20 hours, molten salt is obtained. The molten salt is then removed and placed in a drying oven at 85℃ for natural cooling. The cooled molten salt is then placed in a pulverizer for pulverization to obtain 150-mesh mixed molten salt powder. The mixed molten salt powder is then placed in a drying oven at 90-95℃ for 36-38 hours to obtain a low-melting-point molten salt energy storage material.
[0026] The beneficial effects of this invention are:
[0027] 1. The low-melting-point molten salt energy storage material prepared by this invention involves the introduction of functional fillers generated by the thiol-alkene click reaction of modified silicon carbide nanowires and modified sheet-like zinc-aluminum flakes to composite modify ternary nitrate molten salt. Compared with the unmodified basic molten salt system, the prepared low-melting-point molten salt energy storage material achieves comprehensive improvements in thermal performance, corrosion resistance, cycle stability, and physical structural stability. Its melting point is around 81-93℃, which is lower than that of SolarSalt. Compared with existing mixed molten salts, its melting point is reduced to varying degrees, greatly reducing the overall system cost, improving system safety and stability, obtaining a wider operating temperature range, and improving power generation efficiency.
[0028] 2. The functional filler prepared by this invention has an ultra-high thermal conductivity. After modification with a silane coupling agent, the hydrophobic groups introduced on the surface enable it to disperse uniformly in molten salt without agglomeration or sedimentation, forming a three-dimensional thermally conductive network. The structure of the functional filler is a modified sheet-like structure of zinc-aluminum flakes, which fills the gaps in the network of modified silicon carbide nanowires, further reducing the internal thermal resistance of the molten salt. Compared with the basic ternary molten salt, the thermal conductivity is improved, significantly accelerating the heat transfer rate of the molten salt and reducing the heat loss of the energy storage system. Furthermore, the functional filler can destroy the regular crystalline structure of nitrate through the lattice distortion effect, further lowering the eutectic melting point of the molten salt compared to the unmodified system, thus broadening the low-temperature application range.
[0029] 3. The silicon carbide nanowires in the functional filler prepared by this invention have extremely strong high-temperature chemical inertness. They do not react with nitrates at a melting temperature of 450-500℃, and can also inhibit the generation of oxidizing gas NO2, thereby enhancing corrosion resistance and reducing equipment operation and maintenance costs. Detailed Implementation
[0030] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.
[0031] Example 1: A method for preparing a low-melting-point molten salt energy storage material, comprising the following steps:
[0032] S1: 120g of silicon carbide nanowires, 93mL of 3-mercaptopropyltrimethoxysilane, 300mL of anhydrous ethanol and 929mL of deionized water were added to a reaction vessel. The pH value was adjusted to 3 with hydrochloric acid solution. The mixture was stirred at 20℃ and 500r / min for 22h. After filtration, the precipitate was washed three times with deionized water and anhydrous ethanol and dried under vacuum at 60℃ for 1.6h to obtain modified silicon carbide nanowires.
[0033] S2: 41.0g of zinc powder flakes and 71.1g of aluminum powder flakes were mixed to obtain flaky zinc-aluminum flakes with a thickness of 0.16μm and a diameter of 12.2μm. 115g of flaky zinc-aluminum flakes, 85.1mL of γ-methacryloyloxypropyltrimethoxysilane, 230mL of anhydrous ethanol and 825mL of deionized water were added to a reaction vessel. The pH value was adjusted to 3.9 with hydrochloric acid solution. The mixture was stirred for 22h at 20℃ and 500r / min. After filtration, the precipitate was washed three times with deionized water and anhydrous ethanol and dried under vacuum at 60℃ for 1.6h to obtain modified flaky zinc-aluminum flakes.
[0034] S3: 20g of modified silicon carbide nanowires, 15g of modified sheet-like zinc-aluminum flakes, 0.8g of photoinitiator 2,2-dimethylolpropionic acid and 800mL of tetrahydrofuran were added to a reaction vessel and stirred for 10min at 20℃ and 500r / min. Then, the mixture was reacted for 6h at a wavelength of 365nm and a light intensity of 6mW / cm. After filtration, the precipitate was washed twice with deionized water and anhydrous ethanol, respectively, and dried under vacuum at 60℃ for 1h to obtain the functional filler.
[0035] S4: Mix and grind 500g potassium nitrate, 150g sodium nitrate, 350g calcium nitrate and 7g functional filler, and stir evenly to obtain solid mixed molten salt.
[0036] S5: The solid mixed molten salt is placed in a constant temperature drying oven at 90℃ and dried at a constant temperature for 36 hours. The dried solid mixed molten salt is then placed in a muffle furnace and heated to 450℃ at a heating rate of 8K / min to melt the mixed molten salt. After standing for 18 hours, molten salt is obtained. The molten salt is then removed and placed in a drying oven at 85℃ to cool naturally. The cooled molten salt is then placed in a pulverizer to pulverize it to obtain 150-mesh mixed molten salt powder. The mixed molten salt powder is then placed in a drying oven at 90℃ and dried for 36 hours to obtain a low melting point molten salt energy storage material.
[0037] Example 2: A method for preparing a low-melting-point molten salt energy storage material, comprising the following steps:
[0038] S1: 127.5 g of silicon carbide nanowires, 98 mL of 3-mercaptopropyltrimethoxysilane, 316.5 mL of anhydrous ethanol and 978.5 mL of deionized water were added to a reaction vessel. The pH value was adjusted to 3.5 with hydrochloric acid solution. The mixture was stirred at 22.5 °C and 550 r / min for 23 h. After filtration, the precipitate was washed three times with deionized water and anhydrous ethanol and dried under vacuum at 70 °C for 1.7 h to obtain modified silicon carbide nanowires.
[0039] S2: 43.15g of zinc powder flakes and 74.8g of aluminum powder flakes were mixed to obtain flaky zinc-aluminum flakes with a thickness of 0.17μm and a diameter of 12.85μm. 125g of flaky zinc-aluminum flakes, 90.7mL of γ-methacryloyloxypropyltrimethoxysilane, 241.5mL of anhydrous ethanol and 901.5mL of deionized water were added to a reaction vessel. The pH value was adjusted to 4.0 with hydrochloric acid solution. The mixture was stirred at 22.5℃ and 550r / min for 23h. After filtration, the precipitate was washed three times with deionized water and anhydrous ethanol and dried under vacuum at 70℃ for 1.7h to obtain modified flaky zinc-aluminum flakes.
[0040] S3: 22.5g of modified silicon carbide nanowires, 17.5g of modified sheet-like zinc-aluminum flakes, 0.9g of photoinitiator 2,2-dimethylolpropionic acid and 850mL of tetrahydrofuran were added to a reaction vessel and stirred for 11min at 22.5℃ and 550r / min. Then, the mixture was reacted for 6.5h at a wavelength of 365nm and a light intensity of 6mW / cm. After filtration, the precipitate was washed three times with deionized water and three times with anhydrous ethanol, and then dried under vacuum at 65℃ for 1.5h to obtain the functional filler.
[0041] S4: Mix and grind 510g potassium nitrate, 152.5g sodium nitrate, 353.5g calcium nitrate and 8g functional filler, and stir evenly to obtain solid mixed molten salt.
[0042] S5: The solid mixed molten salt is placed in a constant temperature drying oven at 95℃ and dried for 37 hours. The dried solid mixed molten salt is then placed in a muffle furnace and heated to 475℃ at a heating rate of 9K / min to melt the mixed molten salt. After standing for 19 hours, molten salt is obtained. The molten salt is then removed and placed in a drying oven at 85℃ for natural cooling. The cooled molten salt is then placed in a pulverizer for pulverization to obtain 150-mesh mixed molten salt powder. The mixed molten salt powder is then placed in a drying oven at 92.5℃ for drying for 37 hours to obtain a low-melting-point molten salt energy storage material.
[0043] Example 3: A method for preparing a low-melting-point molten salt energy storage material, comprising the following steps:
[0044] S1: 135g of silicon carbide nanowires, 103mL of 3-mercaptopropyltrimethoxysilane, 333mL of anhydrous ethanol and 1028mL of deionized water were added to a reaction vessel. The pH value was adjusted to 4 with hydrochloric acid solution. The mixture was stirred at 25℃ and 600r / min for 24h. After filtration, the precipitate was washed four times with deionized water and anhydrous ethanol and dried under vacuum at 80℃ for 1.8h to obtain modified silicon carbide nanowires.
[0045] S2: 45.3g of zinc powder flakes and 78.5g of aluminum powder flakes were mixed to obtain flaky zinc-aluminum flakes with a thickness of 0.18μm and a diameter of 13.5μm. 135g of flaky zinc-aluminum flakes, 96.3mL of γ-methacryloyloxypropyltrimethoxysilane, 253mL of anhydrous ethanol and 978mL of deionized water were added to a reaction vessel. The pH was adjusted to 4.1 with hydrochloric acid solution. The mixture was stirred at 25℃ and 600r / min for 24h. After filtration, the precipitate was washed four times with deionized water and anhydrous ethanol and dried under vacuum at 80℃ for 1.8h to obtain modified flaky zinc-aluminum flakes.
[0046] S3: 25g of modified silicon carbide nanowires, 20g of modified sheet-like zinc-aluminum flakes, 1g of photoinitiator 2,2-dimethylolpropionic acid and 900mL of tetrahydrofuran were added to a reaction vessel and stirred for 12min at 25℃ and 600r / min. Then, the mixture was reacted for 7h at a wavelength of 365nm and a light intensity of 6mW / cm. After filtration, the precipitate was washed four times with deionized water and anhydrous ethanol, and then dried under vacuum at 70℃ for 2h to obtain the functional filler.
[0047] S4: Mix and grind 520g potassium nitrate, 155g sodium nitrate, 357g calcium nitrate and 9g functional filler, and stir evenly to obtain solid mixed molten salt.
[0048] S5: The solid mixed molten salt is placed in a constant temperature drying oven at 100℃ and dried for 38 hours. The dried solid mixed molten salt is then placed in a muffle furnace and heated to 500℃ at a heating rate of 10K / min to melt the mixed molten salt. After standing for 20 hours, molten salt is obtained. The molten salt is then removed and placed in a drying oven at 85℃ to cool naturally. The cooled molten salt is then placed in a pulverizer to pulverize it to obtain 150-mesh mixed molten salt powder. The mixed molten salt powder is then placed in a drying oven at 95℃ and dried for 38 hours to obtain a low-melting-point molten salt energy storage material.
[0049] Comparative Example 1: Based on Example 3, the functional filler in step S4 was replaced with the modified silicon carbide nanowires prepared in step S1.
[0050] Comparative Example 2: Based on Example 3, the functional filler in step S4 was replaced with the modified flaky zinc-aluminum flakes prepared in step S2.
[0051] The performance of the low-melting-point molten salt energy storage materials prepared in Examples 1-3 and Comparative Examples 1-2 was tested, and the results are shown in Table 1:
[0052] Table 1
[0053]
[0054] As shown in Table 1, the thermally conductive network in Comparative Example 1 is incomplete, resulting in a significant decrease in thermal performance. Modified silicon carbide nanowires alone cannot form a dense three-dimensional thermally conductive network. The gaps between nanowires are not filled by sheet-like fillers, leading to a substantial increase in the internal thermal resistance of the molten salt, a slowdown in the heat transfer rate, and an increase in heat loss in the energy storage system. The latent heat of phase change decreases, reducing energy storage efficiency. The lack of synergistic effect of lattice distortion from sheet-like zinc-aluminum flakes prevents sufficient disruption of the regular crystalline structure of nitrates, resulting in an increase in the melting point, a simultaneous increase in the primary crystallization point and the melting termination point, and an increase in the minimum lower limit temperature, narrowing the low-temperature application range. This fails to achieve the core objective of a wide operating temperature range of this invention. The structural stability of a single nanowire network is insufficient, and nanowire aggregation is prone to occur after long-term cycling. Although the high-temperature inertia of silicon carbide nanowires is retained, the lack of sheet-like fillers to physically block the molten salt system weakens the effect of suppressing nitrogen dioxide oxidizing gas, increases the corrosion rate, and increases equipment operation and maintenance costs.
[0055] In Comparative Example 2, a stable three-dimensional heat-conducting network cannot be formed, resulting in extremely poor dispersion. The sheet-like zinc-aluminum flakes lack the support of nanowire frameworks. Even after silane modification to introduce hydrophobic groups, they are still prone to interlayer stacking and agglomeration, making it impossible to disperse uniformly in molten salt. This leads to a decrease in thermal conductivity and a significant reduction in heat transfer efficiency, failing to meet the heat transfer requirements of the energy storage system. Furthermore, the lack of lattice distortion synergistic effect from nanowires means that the agglomerated sheet-like filler cannot effectively disrupt the nitrate crystal structure, causing the melting point to rise to near the level of unmodified ternary molten salt. The absence of high-temperature chemical inert protection from silicon carbide nanowires prevents the suppression of nitrogen dioxide oxidizing gas generation. The agglomerated sheet-like filler is prone to structural breakage during the cyclic melting-solidification process, making it impossible to guarantee the long-term operational stability of the system.
[0056] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the invention.
Claims
1. A method for preparing a low-melting-point molten salt energy storage material, characterized in that, Includes the following steps: Step 1: Using 3-mercaptopropyltrimethoxysilane as a modifier, the silanol groups generated by hydrolysis undergo a dehydration condensation reaction with the hydroxyl groups on the surface of silicon carbide nanowires to obtain modified silicon carbide nanowires. Step 2: The flaky zinc-aluminum flakes are treated with γ-methacryloxypropyltrimethoxysilane to obtain modified flaky zinc-aluminum flakes; Step 3: Modified silicon carbide nanowires and modified sheet-like zinc-aluminum flakes undergo a mercapto-olefin click reaction under the action of photoinitiator 2,2-dimethylolpropionic acid to obtain functional fillers; Step 4: Mix and grind potassium nitrate, sodium nitrate, calcium nitrate and functional filler, and stir evenly to obtain solid mixed molten salt; Step 5: Dry the solid mixed molten salt and then calcine it to melt it, obtaining molten salt; cool the molten salt, crush it, and dry it again to obtain low melting point molten salt energy storage material.
2. The method for preparing a low-melting-point molten salt energy storage material according to claim 1, characterized in that, The ratio of potassium nitrate, sodium nitrate, calcium nitrate, and functional filler is 500-520g: 150-155g: 350-357g: 7-9g.
3. The method for preparing a low-melting-point molten salt energy storage material according to claim 1, characterized in that, The specific preparation steps for the modified silicon carbide nanowires are as follows: Silicon carbide nanowires, 3-mercaptopropyltrimethoxysilane, anhydrous ethanol, and deionized water were added to a reaction vessel. The pH was adjusted to 3-4 with hydrochloric acid solution. The mixture was stirred for 22-24 hours at 20-25℃ and 500-600 r / min. After filtration, the precipitate was washed 3-4 times with deionized water and anhydrous ethanol and dried under vacuum at 60-80℃ for 1.6-1.8 hours to obtain modified silicon carbide nanowires.
4. The method for preparing a low-melting-point molten salt energy storage material according to claim 3, characterized in that, The ratio of silicon carbide nanowires, 3-mercaptopropyltrimethoxysilane, anhydrous ethanol, and deionized water is 120-135g: 93-103mL: 300-333mL: 929-1028mL.
5. The method for preparing a low-melting-point molten salt energy storage material according to claim 1, characterized in that, The specific preparation steps for the modified flaky zinc-aluminum flakes are as follows: Add flaky zinc-aluminum flakes, γ-methacryloxypropyltrimethoxysilane, anhydrous ethanol, and deionized water to a reaction vessel, adjust the pH to 3.9-4.1 with hydrochloric acid solution, stir for 22-24 h at 20-25℃ and 500-600 r / min, filter, wash the precipitate 3-4 times with deionized water and anhydrous ethanol, and vacuum dry at 60-80℃ for 1.6-1.8 h to obtain modified flaky zinc-aluminum flakes.
6. The method for preparing a low-melting-point molten salt energy storage material according to claim 5, characterized in that, The ratio of the amount of the zinc-aluminum flakes, γ-methacryloyloxypropyltrimethoxysilane, anhydrous ethanol and deionized water is 115-135g: 85.1-96.3mL: 230-253mL: 825-978mL.
7. The method for preparing a low-melting-point molten salt energy storage material according to claim 1, characterized in that, The specific preparation steps for the functional filler are as follows: Modified silicon carbide nanowires, modified zinc-aluminum flakes, 2,2-dimethylolpropionic acid and tetrahydrofuran were added to a reaction vessel and stirred for 10-12 min at 20-25℃ and 500-600 r / min. Then, the mixture was reacted for 6-7 h at a wavelength of 365 nm and a light intensity of 6 mW / cm. After filtration, the precipitate was washed 2-4 times with deionized water and anhydrous ethanol, respectively, and then dried under vacuum at 60-70℃ for 1-2 h to obtain the functional filler.
8. The method for preparing a low-melting-point molten salt energy storage material according to claim 7, characterized in that, The ratio of the modified silicon carbide nanowires, modified zinc-aluminum flakes, 2,2-dimethylolpropionic acid and tetrahydrofuran is 20-25g: 15-20g: 0.8-1g: 800-900mL.
9. The method for preparing a low-melting-point molten salt energy storage material according to claim 1, characterized in that, The specific preparation steps for the low-melting-point molten salt energy storage material are as follows: Solid mixed molten salt is placed in a constant temperature drying oven at 90-100℃ for 36-38 hours. The dried solid mixed molten salt is then placed in a muffle furnace and heated to 450-500℃ at a heating rate of 8-10K / min to melt the mixed molten salt. After standing for 18-20 hours, molten salt is obtained. The molten salt is then removed and placed in a drying oven at 85℃ for natural cooling. The cooled molten salt is then placed in a pulverizer for pulverization to obtain 150-mesh mixed molten salt powder. The mixed molten salt powder is then placed in a drying oven at 90-95℃ for 36-38 hours to obtain a low-melting-point molten salt energy storage material.
10. A low-melting-point molten salt energy storage material, characterized in that, It is prepared by the preparation method described in any one of claims 1-9.