A eutectic solvent-based metal-carbon composite phase change material and a preparation method thereof

Abstract

The application provides a low-eutectic solvent metal-carbon composite phase change material and a preparation method thereof. The preparation method comprises the following steps: mixing and reacting a hydrogen bond donor and a hydrogen bond acceptor to obtain a low-eutectic solvent; mixing and reacting the low-eutectic solvent, a metal oxide and phosphoric acid to obtain a metal-carbon precursor; sequentially calcining the metal-carbon precursor to obtain a low-eutectic solvent metal-carbon matrix; and mixing the low-eutectic solvent metal-carbon matrix and a liquid phase change material and performing vacuum impregnation to obtain the low-eutectic solvent metal-carbon composite phase change material. The preparation method provided by the application is simple in process, low in cost and has an atomic utilization rate of 100%. The matrix of the obtained composite phase change material maintains high porosity, the thermal conductivity is adjusted through metal elements, the composite phase change material has high heat storage density and photo-thermal conversion efficiency, the latent heat storage density reaches 200 kJ / kg, and the photo-thermal conversion efficiency reaches 83%.

Description

Technical Field

[0001] The present invention belongs to the technical field of phase change materials and relates to a composite phase change material, in particular to a deep eutectic solvent-based metal-carbon composite phase change material and a preparation method thereof. Background Art

[0002] Phase change thermal storage technology utilizes phase change materials to store and release heat during phase changes, with the majority of this heat being latent heat. Due to its high heat storage density and relatively constant phase change temperature, this technology is beneficial for reducing the size of heat storage equipment and facilitating installation and application. It has been widely researched in areas such as building energy conservation, power battery temperature control, and electronic component heat dissipation. However, the common limitations of phase change materials, such as low thermal conductivity and poor heat transfer performance, have severely limited their practical application.

[0003] Prior art improves the performance of phase change materials by combining a high thermal conductivity material with a phase change material to form a composite phase change material. Commonly used matrices include porous nanoparticles, carbon fibers, expanded graphite, and metal foam. For example, CN117821024A discloses a method for preparing a MXene / sorghum straw biomass aerogel-based composite phase change material, using the MXene / sorghum straw biomass aerogel as the phase change material carrier.

[0004] However, although the existing carriers have significantly improved the effective thermal conductivity of the material, it is difficult to ensure the photothermal conversion efficiency and heat storage density. They still face problems such as poor overall performance of composite phase change materials, complex preparation process, high cost of supporting materials, and difficulty in achieving scaled-up preparation.

[0005] Therefore, it is necessary to provide a low eutectic solvent-based metal-carbon composite phase change material and a preparation method thereof. Summary of the Invention

[0006] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a low eutectic solvent-based metal-carbon composite phase change material and a preparation method thereof, which ensures the high heat storage density and thermal conductivity of the material through the low eutectic solvent-based porous carbon carrier and metal components in the material.

[0007] To achieve this object, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a method for preparing a deep eutectic solvent-based metal-carbon composite phase change material, the preparation method comprising the following steps:

[0009] (1) mixing a hydrogen bond donor and a hydrogen bond acceptor to react to obtain a deep eutectic solvent;

[0010] (2) mixing the deep eutectic solvent obtained in step (1), the metal oxide and phosphoric acid to react to obtain a metal-carbon precursor;

[0011] (3) calcining the metal-carbon precursor obtained in step (2) to obtain a low eutectic solvent-based metal-carbon matrix;

[0012] (4) Mixing the low eutectic solvent-based metal-carbon matrix obtained in step (3) with the liquid phase change material and performing vacuum impregnation to obtain a low eutectic solvent-based metal-carbon composite phase change material.

[0013] The preparation method provided by the present invention is based on a template-free process, using a deep eutectic solvent as a carbon source material. Metal oxides are complexed on the deep eutectic solvent. The synthesized metal-carbon matrix is ​​based on the precursor and the material self-decomposes to form a porous structure after the gas volatilization. The matrix maintains a high porosity, and the thermal conductivity is adjusted by the metal in the matrix. The composite phase-change material after impregnation with the phase-change material has both high heat storage density and photothermal conversion efficiency. The preparation process of the present invention can achieve controllable adjustment of the thermal conductivity, heat storage, and photothermal conversion properties of the composite phase-change material, and synthesize composite phase-change energy storage materials with different thermal conductivities, melting points, and photothermal conversion efficiencies, thereby enhancing the application prospects of heat storage technology in different heat sources, different temperature zones, and different scenarios.

[0014] The method provided by the present invention has a simple process flow and low preparation cost. Compared with traditional metal porous media and carbon porous media, it has obvious material cost advantages, and the atomic utilization rate is 100%. The preparation process does not require a large amount of strong acid or strong base, and is easy to scale up.

[0015] Preferably, the hydrogen bond donor in step (1) comprises an organic acid.

[0016] Preferably, the organic acid comprises any one of oxalic acid, lactic acid, citric acid and malic acid, or a combination of at least two thereof. Typical but non-limiting combinations include a combination of oxalic acid and lactic acid, a combination of lactic acid and citric acid, a combination of citric acid and malic acid, a combination of oxalic acid, lactic acid and citric acid, a combination of lactic acid, citric acid and malic acid, or a combination of oxalic acid, lactic acid, citric acid and malic acid.

[0017] Preferably, the hydrogen bond acceptor in step (1) comprises choline chloride.

[0018] Preferably, the molar ratio of the hydrogen bond donor to the hydrogen bond acceptor in step (1) is (1-2):1, for example, 1:1, 1.2:1, 1.5:1, 1.8:1 or 2:1, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0019] Preferably, the mixing method in step (1) includes stirring.

[0020] Preferably, the reaction temperature in step (1) is 70-90°C, for example, 70°C, 75°C, 80°C, 85°C or 90°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0021] Preferably, the reaction time of step (1) is 1.5-2.5 h, for example, 1.5 h, 1.8 h, 2 h, 2.3 h or 2.5 h, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0022] Preferably, the metal element of the metal oxide in step (2) includes any one or a combination of at least two of Al, Fe, Ni, Cu or Bi. Typical but non-limiting combinations include a combination of Al and Fe, a combination of Ni and Cu, a combination of Cu and Bi, a combination of Al, Fe and Ni, a combination of Ni, Cu and Bi, or a combination of Al, Fe, Ni, Cu and Bi.

[0023] Preferably, the mass ratio of the deep eutectic solvent to the metal oxide in step (2) is (100-600):1, for example, it can be 100:1, 200:1, 300:1, 400:1, 500:1 or 600:1, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0024] Preferably, the molar ratio of the metal oxide to phosphoric acid in step (2) is 1:1, ensuring that the molar ratio of phosphorus atoms to metal atoms is 1:1.

[0025] Preferably, the mixing method in step (2) includes stirring.

[0026] Preferably, the reaction temperature in step (2) is 120-140°C, for example, 120°C, 125°C, 130°C, 135°C or 140°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0027] Preferably, the reaction time of step (2) is 5-7 h, for example, 5 h, 5.5 h, 6 h, 6.5 h or 7 h, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0028] Preferably, the heating rate of the calcination in step (3) is 2-3°C / min, for example, it can be 2°C / min, 2.2°C / min, 2.5°C / min, 2.8°C / min or 3°C / min, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0029] Preferably, the calcination process in step (3) comprises: heating to 90-110°C, 140-160°C, 190-210°C, 240-260°C, 290-310°C, 340-360°C and 390-410°C in sequence, and independently keeping the temperature in each temperature range for 1.4-1.6 hours.

[0030] The temperature is raised to 90-110° C., for example, 90° C., 95° C., 100° C., 105° C. or 110° C., but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0031] The temperature is raised to 140-160° C., for example, 140° C., 145° C., 150° C., 155° C. or 160° C., but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0032] The temperature is raised to 190-210° C., for example, 190° C., 195° C., 200° C., 205° C. or 210° C., but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0033] The temperature is raised to 240-260°C, for example, 240°C, 245°C, 250°C, 255°C or 260°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0034] The temperature is raised to 290-310°C, for example, 290°C, 295°C, 300°C, 305°C or 310°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0035] The temperature is raised to 340-360°C, for example, 340°C, 345°C, 350°C, 355°C or 360°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0036] The temperature is raised to 390-410°C, for example, 390°C, 395°C, 400°C, 405°C or 410°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0037] The holding time is 1.4-1.6 hours, for example, 1.4 hours, 1.45 hours, 1.5 hours, 1.55 hours or 1.6 hours, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0038] Preferably, in step (4), the liquid phase change material is in excess compared to the deep eutectic solvent-based metal-carbon matrix.

[0039] Preferably, the temperature of the vacuum impregnation in step (4) is 120-140°C, for example, 120°C, 125°C, 130°C, 135°C or 140°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0040] Preferably, the vacuum impregnation time in step (4) is 10-14 hours, for example, 10 hours, 11 hours, 12 hours, 13 hours or 14 hours, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0041] As a preferred technical solution of the preparation method provided by the present invention, the preparation method comprises the following steps:

[0042] (1) A hydrogen bond donor and a hydrogen bond acceptor are stirred and mixed at a molar ratio of (1-2):1, and a eutectic reaction is carried out at 70-90°C for 1.5-2.5 hours to obtain a deep eutectic solvent;

[0043] (2) mixing the deep eutectic solvent obtained in step (1), the metal oxide and phosphoric acid, wherein the mass ratio of the deep eutectic solvent to the metal oxide is (100-600):1, and the molar ratio of the metal oxide to the phosphoric acid is 1:(0.9-1.1), and performing a complexation reaction at 120-140° C. for 5-7 hours to obtain a metal-carbon precursor;

[0044] (3) calcining the metal-carbon precursor obtained in step (2), heating the mixture to 90-110°C at a heating rate of 2-3°C / min and keeping the mixture for 1.4-1.6 h, 140-160°C at a heating rate of 1.4-1.6 h, 190-210°C at a heating rate of 1.4-1.6 h, 240-260°C at a heating rate of 1.4-1.6 h, 290-310°C at a heating rate of 1.4-1.6 h, 340-360°C at a heating rate of 1.4-1.6 h, and 400-500°C at a heating rate of 1.4-1.6 h, cooling the mixture and collecting the mixture to obtain a low eutectic solvent-based metal-carbon matrix;

[0045] (4) Mixing the low eutectic solvent-based metal-carbon matrix obtained in step (3) with the liquid phase change material, and performing vacuum impregnation at 120-140° C. for 10-14 hours to obtain the low eutectic solvent-based metal-carbon composite phase change material.

[0046] In a second aspect, the present invention provides a deep eutectic solvent-based metal-carbon composite phase change material, wherein the deep eutectic solvent-based metal-carbon composite phase change material is prepared by the preparation method described in the first aspect.

[0047] The composite phase change material matrix provided by the present invention maintains high porosity, achieves thermal conductivity adjustment through metal elements, and has both high heat storage density and light-to-heat conversion efficiency.

[0048] Compared with the prior art, the present invention has the following beneficial effects:

[0049] The preparation method provided by the present invention has a simple process, low cost, and an atomic utilization rate of 100%. The matrix of the obtained composite phase change material maintains a high porosity, and the thermal conductivity is adjusted by metal elements. It has both high heat storage density and photothermal conversion efficiency. The latent heat storage density reaches 200kJ / kg, and the photothermal conversion efficiency reaches 83%. DETAILED DESCRIPTION

[0050] The technical solution of the present invention is further illustrated below through specific implementation methods.

[0051] Example 1

[0052] This embodiment provides a method for preparing a deep eutectic solvent-based metal-carbon composite phase change material, the preparation method comprising the following steps:

[0053] (1) 23.02 g of oxalic acid and 35 g of choline chloride were mixed evenly, i.e., the molar ratio of oxalic acid to choline chloride was 1:1, and the mixture was fully stirred in a magnetic stirrer to form a solution. The solution was heated to 80° C. and maintained for 2 hours to perform a eutectic reaction to obtain a deep eutectic solvent;

[0054] (2) adding 0.29 g of anhydrous copper oxide to a deep eutectic solvent and adding 0.41 g of phosphoric acid solution, wherein the mass ratio of the deep eutectic solvent to copper oxide is 200:1, and the molar ratio of copper oxide to phosphoric acid is 1:1, and fully stirring and dissolving at 130° C. for 6 hours to obtain a metal-carbon precursor through a complex reaction;

[0055] (3) The obtained metal-carbon precursor was placed in a box-type resistance furnace and heated to 100°C at a heating rate of 2.5°C / min, kept warm for 1.5h, then heated to 150°C, kept warm for 1.5h, then heated to 200°C, kept warm for 1.5h, then heated to 250°C, kept warm for 1.5h, then heated to 300°C, kept warm for 1.5h, then heated to 350°C, kept warm for 1.5h, then heated to 400°C, kept warm for 1.5h. After the product was cooled to room temperature, it was collected to obtain a porous metal-carbon matrix;

[0056] (4) 2 g of the porous metal-carbon matrix and an excess of liquid erythritol were placed in a vacuum impregnation apparatus and stirred and adsorbed thoroughly. After being kept at a constant temperature of 130° C. for 12 hours, the precipitate was taken out to obtain a low eutectic solvent-based metal-carbon composite phase change material.

[0057] Example 2

[0058] This embodiment provides a method for preparing a deep eutectic solvent-based metal-carbon composite phase change material, the preparation method comprising the following steps:

[0059] (1) 23.02 g of oxalic acid and 35 g of choline chloride were mixed evenly, i.e., the molar ratio of oxalic acid to choline chloride was 1:1, and the mixture was fully stirred in a magnetic stirrer to form a solution. The solution was heated to 70° C. and maintained for 2.5 hours to perform a eutectic reaction to obtain a deep eutectic solvent;

[0060] (2) adding 0.29 g of anhydrous copper oxide to a deep eutectic solvent and adding 0.41 g of phosphoric acid solution, wherein the mass ratio of the deep eutectic solvent to copper oxide is 200:1, and the molar ratio of copper oxide to phosphoric acid is 1:1, and fully stirring and dissolving at 120° C. for 7 hours to obtain a metal-carbon precursor through a complex reaction;

[0061] (3) The obtained metal-carbon precursor was placed in a box-type resistance furnace and heated to 100°C at a heating rate of 2°C / min, kept warm for 1.5h, then heated to 150°C, kept warm for 1.5h, then heated to 200°C, kept warm for 1.5h, then heated to 250°C, kept warm for 1.5h, then heated to 300°C, kept warm for 1.5h, then heated to 350°C, kept warm for 1.5h, then heated to 400°C, kept warm for 1.5h. After the product was cooled to room temperature, it was collected to obtain a porous metal-carbon matrix;

[0062] (4) 2 g of the porous metal-carbon matrix and an excess of liquid erythritol were placed in a vacuum impregnation apparatus and stirred and adsorbed thoroughly. After being kept at a constant temperature of 140° C. for 14 hours, the precipitate was taken out to obtain a low eutectic solvent-based metal-carbon composite phase change material.

[0063] Example 3

[0064] This embodiment provides a method for preparing a deep eutectic solvent-based metal-carbon composite phase change material, the preparation method comprising the following steps:

[0065] (1) 23.02 g of oxalic acid and 35 g of choline chloride were mixed evenly, i.e., the molar ratio of oxalic acid to choline chloride was 1:1, and the mixture was fully stirred in a magnetic stirrer to form a solution. The solution was heated to 90° C. and maintained for 1.5 hours to perform a eutectic reaction to obtain a deep eutectic solvent;

[0066] (2) adding 0.29 g of anhydrous copper oxide to a deep eutectic solvent and adding 0.41 g of phosphoric acid solution, wherein the mass ratio of the deep eutectic solvent to copper oxide is 200:1, and the molar ratio of copper oxide to phosphoric acid is 1:1, and fully stirring and dissolving at 140° C. for 5 hours to obtain a metal-carbon precursor through a complex reaction;

[0067] (3) The obtained metal-carbon precursor is placed in a box-type resistance furnace, and is heated at a heating rate of 3℃ / min to 100℃ first, 150℃ second, 200℃ third, 250℃ fourth, 300℃ fifth, 350℃ sixth, 400℃ seventh, and is kept for 1.5h after each temperature, and after the product is cooled to room temperature, a porous metal-carbon matrix is collected;

[0068] (4) 2g of the porous metal-carbon matrix is placed in a vacuum impregnator with excess liquid erythritol, and is stirred and adsorbed, and after being kept at 120℃ for 10h, the precipitate is taken out to obtain a metal-carbon composite phase change material of a eutectic solvent.

[0069] Example 4

[0070] The present example provides a preparation method of a metal-carbon composite phase change material of a eutectic solvent, wherein the hydrogen bond donor in step (1) is replaced by 22.58g of lactic acid instead of oxalic acid, i.e. the molar ratio of the hydrogen bond donor to the hydrogen bond acceptor is 1:1, and the rest is the same as in Example 1.

[0071] Example 5

[0072] The present example provides a preparation method of a metal-carbon composite phase change material of a eutectic solvent, wherein the hydrogen bond donor in step (1) is replaced by 48.16g of citric acid instead of oxalic acid, i.e. the molar ratio of the hydrogen bond donor to the hydrogen bond acceptor is 1:1, and the rest is the same as in Example 1.

[0073] Example 6

[0074] The present example provides a preparation method of a metal-carbon composite phase change material of a eutectic solvent, wherein the hydrogen bond donor in step (1) is replaced by 33.61g of malic acid instead of oxalic acid, i.e. the molar ratio of the hydrogen bond donor to the hydrogen bond acceptor is 1:1, and the rest is the same as in Example 1.

[0075] Example 7

[0076] The present example provides a preparation method of a metal-carbon composite phase change material of a eutectic solvent, wherein the hydrogen bond donor in step (1) is replaced by 50.42g of malic acid instead of oxalic acid, i.e. the molar ratio of the hydrogen bond donor to the hydrogen bond acceptor is 1.5:1, and the rest is the same as in Example 1.

[0077] Example 8

[0078] This embodiment provides a method for preparing a low eutectic solvent-based metal-carbon composite phase change material. Compared with Example 1, the hydrogen bond donor in step (1) is replaced by oxalic acid with 67.22 g of malic acid, that is, the molar ratio of the hydrogen bond donor to the hydrogen bond acceptor is 2:1. The rest is the same as Example 1.

[0079] Example 9

[0080] This embodiment provides a method for preparing a low eutectic solvent-based metal-carbon composite phase change material. Compared with Example 1, the metal oxide in step (2) is replaced by aluminum oxide by an equal mass of copper oxide, and the rest is the same as Example 1.

[0081] Example 10

[0082] This embodiment provides a method for preparing a low eutectic solvent-based metal-carbon composite phase change material. Compared with Example 1, the metal oxide in step (2) is replaced by iron oxide by an equal mass of copper oxide, and the rest is the same as Example 1.

[0083] Example 11

[0084] This embodiment provides a method for preparing a low eutectic solvent-based metal-carbon composite phase change material. Compared with Example 1, the metal oxide in step (2) is replaced by bismuth oxide by an equal mass of copper oxide, and the rest is the same as Example 1.

[0085] Example 12

[0086] This embodiment provides a method for preparing a low eutectic solvent-based metal-carbon composite phase change material. Compared with Example 1, the metal oxide in step (2) uses 0.15 g of copper oxide, that is, the mass ratio of the low eutectic solvent to the metal oxide is 400:1, and the rest is the same as Example 1.

[0087] Example 14

[0088] This embodiment provides a method for preparing a low eutectic solvent-based metal-carbon composite phase change material. Compared with Example 1, the metal oxide in step (2) uses 0.1 g of copper oxide, that is, the mass ratio of the low eutectic solvent to the metal oxide is 600:1, and the rest is the same as Example 1.

[0089] Example 15

[0090] This embodiment provides a method for preparing a low eutectic solvent-based metal-carbon composite phase change material. Compared with Example 1, the maximum temperature in step (3) is controlled to be raised to 500° C., and the rest is the same as Example 1.

[0091] Example 16

[0092] This embodiment provides a method for preparing a low eutectic solvent-based metal-carbon composite phase change material. Compared with Example 1, the calcination process in step (3) is to directly increase the temperature to 400°C at 2.5°C / min and keep the temperature for 10.5h. The rest is the same as Example 1.

[0093] Example 17

[0094] This embodiment provides a method for preparing a low eutectic solvent-based metal-carbon composite phase change material. Compared with Example 1, the liquid phase change material in step (4) is replaced by an equal amount of liquid erythritol with paraffin, and the rest is the same as Example 1.

[0095] Example 18

[0096] This embodiment provides a method for preparing a low eutectic solvent-based metal-carbon composite phase change material. Compared with Example 1, the liquid phase change material in step (4) is replaced by an equal amount of liquid erythritol with NaCH3COO·3H2O, and the rest is the same as Example 1.

[0097] Example 19

[0098] This embodiment provides a method for preparing a deep eutectic solvent-based metal-carbon composite phase change material. Compared with Example 1, the choline chloride in step (1) is replaced by betaine in equal amounts, and the rest is the same as Example 1.

[0099] Example 20

[0100] This embodiment provides a method for preparing a low eutectic solvent-based metal-carbon composite phase change material. Compared with Example 1, an equal amount of oxalic acid in step (1) is replaced by succinic acid, and the rest is the same as Example 1.

[0101] Comparative Example 1

[0102] This comparative example provides a method for preparing a low eutectic solvent-based carbon composite phase change material. Compared with Example 1, no metal oxide is added in step (2), and the rest is the same as Example 1.

[0103] Comparative Example 2

[0104] This comparative example provides a method for preparing a composite phase change material. Compared with Example 1, the low eutectic solvent in step (1) is replaced by expanded graphite in equal amounts, and the rest is the same as Example 1.

[0105] The porosity of the matrix prepared in step (3) in the examples and comparative examples was determined by mercury intrusion method, and the thermal conductivity, heat storage density and photo-thermal conversion efficiency of the prepared composite phase change materials were determined, the test method of thermal conductivity was laser thermal conductivity method, the test method of heat storage density was differential scanning calorimetry, and the test method of photo-thermal conversion efficiency was the ratio of the sum of sensible heat and latent heat of the eutectic solvent-based carbon composite phase change material in a certain time and temperature range to the light radiation energy received in the time, and the obtained results are listed in Table 1.

[0106] Table 1

[0107]

[0108]

[0109] As can be seen from Table 1, the greater the porosity, the stronger the adsorption capacity of the metal-carbon matrix to the phase change material, and the greater the latent heat storage density; the porosity of the metal-carbon matrix obtained by step-by-step heating calcination is greater than that obtained by direct heating calcination; the slower the heating rate, the greater the porosity; the porosity and thermal conductivity of the metal-carbon matrix obtained by different types of hydrogen bond donors and acceptors are different; the metal oxide significantly improves the thermal conductivity of the composite material; the higher the content of the metal oxide, the greater the thermal conductivity of the composite material; the higher the thermal conductivity of the composite material, the higher the photo-thermal conversion efficiency; the stronger the absorption capacity of the metal in the metal oxide to different wavebands of light, the higher the photo-thermal conversion efficiency; and the type of phase change material directly affects the latent heat storage density of the composite material.

[0110] The above specific examples further illustrate the purpose, technical solutions and beneficial effects of the present application, and it should be understood that the above description is only a specific embodiment of the present application and is not intended to limit the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A method for preparing a deep eutectic solvent-based metal-carbon composite phase change material, characterized in that: The preparation method comprises the following steps: (1) mixing a hydrogen bond donor and a hydrogen bond acceptor to react to obtain a deep eutectic solvent; wherein the hydrogen bond donor comprises an organic acid, the organic acid comprises any one or a combination of at least two of oxalic acid, lactic acid, citric acid and malic acid, the hydrogen bond acceptor comprises choline chloride, and the molar ratio of the hydrogen bond donor to the hydrogen bond acceptor is (1-2):1; (2) mixing the low eutectic solvent obtained in step (1), the metal oxide and phosphoric acid to obtain a metal-carbon precursor; wherein the metal element of the metal oxide includes any one of Al, Fe, Ni, Cu or Bi or a combination of at least two thereof; (3) calcining the metal-carbon precursor obtained in step (2) to obtain a low eutectic solvent-based metal-carbon matrix; (4) The low eutectic solvent-based metal-carbon matrix obtained in step (3) is mixed with a liquid phase change material and vacuum impregnated to obtain a low eutectic solvent-based metal-carbon composite phase change material.

2. The preparation method according to claim 1, characterized in that The reaction temperature in step (1) is 70-90°C.

3. The preparation method according to claim 1, characterized in that The reaction time of step (1) is 1.5-2.5h.

4. The preparation method according to claim 1, characterized in that The mass ratio of the low eutectic solvent to the metal oxide in step (2) is (100-600):

1.

5. The preparation method according to claim 1, characterized in that The molar ratio of the metal oxide to phosphoric acid in step (2) is 1:

1.

6. The preparation method according to claim 1, characterized in that The reaction temperature in step (2) is 120-140°C.

7. The preparation method according to claim 1, characterized in that The reaction time of step (2) is 5-7 hours.

8. The preparation method according to claim 1, characterized in that The heating rate of the calcination in step (3) is 2-3°C / min.

9. The preparation method according to claim 1, characterized in that The calcination process in step (3) includes: heating to 90-110°C, 140-160°C, 190-210°C, 240-260°C, 290-310°C, 340-360°C and 390-410°C in sequence, and keeping each temperature range independently for 1.4-1.6 hours.

10. The preparation method according to claim 1, characterized in that The temperature of the vacuum impregnation in step (4) is 120-140°C.

11. The preparation method according to claim 1, characterized in that The vacuum impregnation time in step (4) is 10-14 hours.

12. The preparation method according to claim 1, characterized in that The preparation method comprises the following steps: (1) A hydrogen bond donor and a hydrogen bond acceptor are stirred and mixed at a molar ratio of (1-2):1, and a eutectic reaction is carried out at 70-90°C for 1.5-2.5 hours to obtain a deep eutectic solvent; (2) mixing the deep eutectic solvent obtained in step (1), the metal oxide and phosphoric acid, wherein the mass ratio of the deep eutectic solvent to the metal oxide is (100-600):1, and the molar ratio of the metal oxide to the phosphoric acid is 1:(0.9-1.1), and conducting a complexation reaction at 120-140° C. for 5-7 h to obtain a metal-carbon precursor; (3) calcining the metal-carbon precursor obtained in step (2), heating the temperature to 90-110°C at a heating rate of 2-3°C / min, and keeping the temperature therefor for 1.4-1.6 h, 140-160°C, 190-210°C, 240-260°C, 290-310°C, 340-360°C, and 390-410°C for 1.4-1.6 h, and cooling the product to obtain a low eutectic solvent-based metal-carbon matrix; (4) The low eutectic solvent-based metal-carbon matrix obtained in step (3) is mixed with a liquid phase change material, and vacuum impregnation is performed at 120-140° C. for 10-14 hours to obtain the low eutectic solvent-based metal-carbon composite phase change material.

13. A deep eutectic solvent-based metal-carbon composite phase change material, characterized in that: The deep eutectic solvent-based metal-carbon composite phase change material is prepared by the preparation method according to any one of claims 1 to 12.

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