Vertically-oriented high-thermal-conductivity hydrated salt composite phase change gel material as well as preparation method and application of vertically-oriented high-thermal-conductivity hydrated salt composite phase change gel material

Abstract

The invention belongs to the technical field of phase change materials, and provides a vertically-oriented high-thermal-conductivity hydrated salt composite phase change gel material as well as a preparation method and application thereof. According to the invention, the hydrated salt gel solution and the heat-conducting filler sheets are alternately stacked, and vertical cutting is carried out after illumination-initiated polymerization of each layer of gel, so that a composite structure with a directional heat-conducting channel is constructed. According to the material, the heat conductivity is remarkably improved while the extremely low content of the heat-conducting filler is kept, the material has a high phase change enthalpy value and structural stability, and the problems that in the prior art, the enthalpy value is reduced, and the filler is distributed disorderly due to the heat-conducting filler are solved. And the preparation process is simple, and is suitable for various application scenes requiring directional heat conduction and high energy storage density, such as battery heat management, flexible electronics and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of phase change materials, and in particular to a vertically oriented high thermal conductivity hydrated salt composite phase change gel material, a preparation method and application thereof. Background Art

[0002] As the power density of electronic devices and energy storage systems continues to increase, the heat generated during their operation increases significantly, leading to localized overheating, performance degradation, reduced reliability, and even safety hazards. In areas such as power batteries, 5G communications equipment, chips, and high-performance computing devices, thermal management has become a key factor limiting performance improvements and safe operation. Therefore, the development of efficient, fast-response, and high-heat-capacity thermal management materials and structures has become a research hotspot.

[0003] While traditional active cooling systems, such as air cooling and liquid cooling, offer strong heat dissipation capabilities, they often suffer from complex structures, high energy consumption, and high maintenance costs. In contrast, passive thermal management technologies, particularly those based on phase change materials (PCMs), have garnered widespread attention due to their high efficiency, compact structure, and fast response times, enabling temperature control without external energy input.

[0004] Among phase change materials, hydrated salts, a typical inorganic PCM, offer advantages such as high latent heat of change, a well-defined phase transition temperature, excellent thermal stability, and low cost. Therefore, they are widely considered one of the most promising thermal storage materials for large-scale thermal management systems. However, practical applications of hydrated salts present significant phase separation, high undercooling, and flow leakage, which severely limit their stability and cycle life.

[0005] To overcome these shortcomings, hydrated salt composite gel phase change materials, based on three-dimensional polymer hydrogel networks, have been developed in recent years. This system utilizes the physical confinement of the hydrated salt by the gel network to effectively inhibit its migration and stratification, enhancing the stability and formability of the thermal storage system. The hydrated salt-gel composite system forms a spatial network structure through cross-linking between polymer chains, which securely encapsulates the hydrated salt within the gel, significantly improving its mechanical conformability and anti-leakage properties. It exhibits excellent adaptability in flexible electronics, wearable devices, and battery thermal management.

[0006] In the prior art, for example, Chinese patent applications CN118271514A and CN116102744A respectively disclose methods of combining inorganic hydrated salts with hydrogels and introducing photothermal materials to enhance thermal response performance. The resulting materials perform well in terms of shape stability, energy storage density, and mechanical properties. However, this type of material still faces a significant trade-off between thermal properties and structural performance: on the one hand, the hydrogel system itself has a low thermal conductivity, making it difficult to meet the demand for rapid heat dissipation; on the other hand, high thermal conductivity fillers such as graphene and metal oxides are often introduced to improve thermal conductivity, but this often dilutes the hydrated salt content, resulting in a decrease in the phase change enthalpy value and may destroy the cross-linked network structure of the gel, thereby affecting the flexibility and stability of the material.

[0007] In addition, the uncontrollable distribution and disordered arrangement of thermal conductive fillers often lead to anisotropy of thermal conduction. Especially in application scenarios such as cylindrical batteries or chips that have a clear demand for radial heat dissipation, traditional filler strategies are difficult to achieve ideal directional thermal conductivity effects.

[0008] Therefore, one of the key challenges in current research on hydrated salt gel phase change materials is how to improve thermal conductivity while maintaining or even enhancing the material's phase change latent heat and gel structural integrity, particularly achieving efficient and uniform heat conduction in the radial direction. Developing a composite structure that can achieve directional heat conduction enhancement with a low thermally conductive filler content while retaining phase change properties and mechanical stability has become a pressing issue for researchers in this field. Summary of the Invention

[0009] The purpose of the present invention is to overcome the problems existing in the prior art and provide a vertically oriented high thermal conductivity hydrated salt composite phase change gel material and a preparation method and application thereof.

[0010] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions: The present invention provides a vertically oriented high thermal conductivity hydrated salt composite phase change gel material, comprising the following raw materials in parts by weight: 10-30 parts of gel monomer, 0.03-0.5 parts of cross-linking agent, 0.005-0.5 parts of initiator, 0-5 parts of nucleating agent, 50-90 parts of hydrated salt, 0-10 parts of temperature regulator, and 0-5 parts of thermal conductive filler.

[0011] Furthermore, the gel monomer includes one or more of acrylamide, acrylic acid and 2-acrylamido-2-methyl-1-propanesulfonic acid; and the cross-linking agent includes N,N′-methylenebisacrylamide.

[0012] Further, the initiator includes one or more of ammonium persulfate, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 1-hydroxy-cyclohexyl-phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, benzoin dimethyl ether, benzophenone, 2-isopropylthioxanthone, 4-isopropylthioxanthone, 2-methyl-1-(4-methylthiophenyl)-2-morpholinyl-1-propanone, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, 2-hydroxy-1-(4-(2-hydroxy-2-methylpropionylphenyl)benzyl)-2-methyl-1-propanone, 2,2-diethoxyacetylphenol, 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone and α-ketoglutaric acid.

[0013] Furthermore, the nucleating agent includes one or more of disodium hydrogen phosphate dodecahydrate, sodium carbonate decahydrate, strontium chloride hexahydrate, barium hydroxide octahydrate, sodium silicate nonahydrate, sodium tetraborate decahydrate, sodium hexametaphosphate, calcium chloride dihydrate, sodium borate decahydrate and sodium pyrophosphate decahydrate.

[0014] Furthermore, the hydrated salt includes one or more of sodium acetate trihydrate, sodium sulfate decahydrate, sodium thiosulfate pentahydrate, calcium chloride hexahydrate, disodium hydrogen phosphate dodecahydrate, magnesium chloride hexahydrate, sodium carbonate decahydrate, zinc chloride tetrahydrate, sodium tetraborate decahydrate, magnesium acetate tetrahydrate, magnesium nitrate hexahydrate, calcium nitrate tetrahydrate, aluminum nitrate nonahydrate, zinc nitrate hexahydrate and ammonium aluminum sulfate dodecahydrate.

[0015] Furthermore, the temperature regulator includes one or more of urea, sodium chloride and potassium nitrate; The thermally conductive filler includes one or more of a boron nitride sheet, a graphite film, a polyethylene film, an aluminum nitride film, a silicon carbide film, polyimide, and a graphene film.

[0016] The present invention provides a method for preparing the vertically oriented high thermal conductivity hydrated salt composite phase change gel material, comprising the following steps: S1, mixing a hydrated salt, a nucleating agent, a temperature regulator, a gel monomer, a crosslinking agent, and an initiator, and heating the mixture in a water bath to obtain a mixed solution; S2, alternately layering the mixed solution and thermally conductive filler sheets, initiating polymerization using ultraviolet light, and then demolding to obtain a pre-material; S3. After vertically cutting the pre-material, a vertically oriented high thermal conductivity hydrated salt composite phase change gel material is obtained.

[0017] Furthermore, in step S1, the temperature of the water bath heating is 30-90°C.

[0018] Furthermore, in step S2, the ultraviolet light irradiation time is 1 to 60 minutes.

[0019] The present invention also provides the application of the vertically oriented high thermal conductivity hydrated salt composite phase change gel material in the field of thermal management.

[0020] It can be seen from the above technical solution that compared with the prior art, the beneficial effects of the present invention are as follows: 1. Combining efficient thermal conductivity with structural directionality: By constructing a vertically oriented thermally conductive filler layer, a significant improvement in thermal conductivity is achieved with extremely low filler content. The orderly arrangement of the thermal conductive channels ensures rapid heat dissipation in one direction, making it particularly suitable for applications requiring directional thermal management, such as battery housings and chip cooling.

[0021] 2. Balancing high energy storage density and stability: The present invention avoids the problem of enthalpy drop caused by high-dose doping of traditional thermal conductive fillers. Through the layered structure and limited filler strategy, the high phase change enthalpy of the hydrated salt is significantly retained, and the hydrogel network structure is complete, which effectively prevents material leakage, stratification and other phenomena, and improves the cycle stability.

[0022] 3. The preparation process is simple and suitable for large-scale promotion: the method combines layered laying with ultraviolet light in-situ polymerization, which is gentle to operate and has controllable parameters. The overall preparation process is simple and suitable for continuous manufacturing and preparation of materials of different sizes / shapes, laying the foundation for subsequent industrial applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a process flow chart for preparing a vertically oriented high thermal conductivity hydrated salt composite phase change gel material according to the present invention; Figure 2 This is a physical picture of the boron nitride-doped hydrated salt gel composite phase change gel material obtained in Example 1; Figure 3 This is a physical picture of the graphite-doped hydrated salt gel composite phase change gel material obtained in Example 2; Figure 4 This is a physical picture of the hydrated salt gel composite phase change gel material obtained in Comparative Example 1; Figure 5 This is a physical picture of the hydrated salt gel composite phase change gel material obtained in Comparative Example 2; Figure 6 This is a comparison diagram of the DSC curves of the boron nitride-doped hydrated salt gel composite phase change gel material obtained in Example 1 and the materials obtained in Comparative Examples 1 and 2; Figure 7 3. This is a comparison chart of the phase transition temperature and phase transition enthalpy values ​​of the boron nitride-doped hydrated salt gel composite phase change gel material obtained in Example 1 and the materials obtained in Comparative Examples 1 and 2; Figure 8 This is a comparison chart of the thermal conductivity of the boron nitride-doped hydrated salt gel composite phase change gel material obtained in Example 1 and the materials obtained in Comparative Examples 1 and 2; Figure 9 This is a physical picture of the boron nitride powder-doped hydrated salt gel composite phase change gel material obtained in Comparative Example 3; Figure 10 This is a physical picture of the hydrated salt gel composite phase change gel material doped with graphite powder obtained in Comparative Example 4; Figure 11 This is a comparison diagram of the DSC curves of the graphite-doped hydrated salt gel composite phase change gel material obtained in Example 2 and the materials obtained in Comparative Examples 3 and 4; Figure 12 1 is a comparison chart of the phase change temperature and phase change enthalpy values ​​of the graphite-doped hydrated salt gel composite phase change gel material obtained in Example 2 and the materials obtained in Comparative Examples 3 and 4; Figure 13 This is a comparison chart of the thermal conductivity of the graphite-doped hydrated salt gel composite phase change gel material obtained in Example 2 and the materials obtained in Comparative Examples 3 and 4. DETAILED DESCRIPTION

[0024] The present invention provides a vertically oriented high thermal conductivity hydrated salt composite phase change gel material, comprising the following raw materials in parts by weight: 10-30 parts of gel monomer, 0.03-0.5 parts of cross-linking agent, 0.005-0.5 parts of initiator, 0-5 parts of nucleating agent, 50-90 parts of hydrated salt, 0-10 parts of temperature regulator, and 0-5 parts of thermal conductive filler.

[0025] In the present invention, the amount of the gel monomer is preferably 15 to 25 parts, more preferably 20 parts.

[0026] In the present invention, the amount of the cross-linking agent is preferably 0.1 to 0.4 parts, more preferably 0.2 to 0.3 parts.

[0027] In the present invention, the amount of the initiator is preferably 0.1 to 0.4 parts, more preferably 0.2 to 0.3 parts.

[0028] In the present invention, the amount of the nucleating agent is preferably 1 to 4 parts, more preferably 2 to 3 parts.

[0029] In the present invention, the amount of the hydrated salt is preferably 60 to 80 parts, more preferably 70 parts.

[0030] In the present invention, the amount of the temperature regulator is preferably 2 to 8 parts, more preferably 4 to 6 parts.

[0031] In the present invention, the amount of the thermally conductive filler sheet is preferably 1 to 4 parts, more preferably 2 to 3 parts.

[0032] In the present invention, the gel monomer includes one or more of acrylamide, acrylic acid and 2-acrylamido-2-methyl-1-propanesulfonic acid; and the cross-linking agent includes N,N′-methylenebisacrylamide.

[0033] In the present invention, the initiator includes one or more of ammonium persulfate, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 1-hydroxy-cyclohexyl-phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, benzoin dimethyl ether, benzophenone, 2-isopropylthioxanthone, 4-isopropylthioxanthone, 2-methyl-1-(4-methylthiophenyl)-2-morpholinyl-1-propanone, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, 2-hydroxy-1-(4-(2-hydroxy-2-methylpropionylphenyl)benzyl)-2-methyl-1-propanone, 2,2-diethoxyacetylphenol, 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone and α-ketoglutaric acid.

[0034] In the present invention, the nucleating agent includes one or more of disodium hydrogen phosphate dodecahydrate, sodium carbonate decahydrate, strontium chloride hexahydrate, barium hydroxide octahydrate, sodium silicate nonahydrate, sodium tetraborate decahydrate, sodium hexametaphosphate, calcium chloride dihydrate, sodium borate decahydrate and sodium pyrophosphate decahydrate.

[0035] In the present invention, the hydrated salt includes one or more of sodium acetate trihydrate, sodium sulfate decahydrate, sodium thiosulfate pentahydrate, calcium chloride hexahydrate, disodium hydrogen phosphate dodecahydrate, magnesium chloride hexahydrate, sodium carbonate decahydrate, zinc chloride tetrahydrate, sodium tetraborate decahydrate, magnesium acetate tetrahydrate, magnesium nitrate hexahydrate, calcium nitrate tetrahydrate, aluminum nitrate nonahydrate, zinc nitrate hexahydrate and ammonium aluminum sulfate dodecahydrate.

[0036] In the present invention, the temperature regulator includes one or more of urea, sodium chloride and potassium nitrate; The thermally conductive filler includes one or more of a boron nitride sheet, a graphite film, a polyethylene film, an aluminum nitride film, a silicon carbide film, polyimide, and a graphene film.

[0037] The present invention provides a method for preparing the vertically oriented high thermal conductivity hydrated salt composite phase change gel material, comprising the following steps: S1, mixing a hydrated salt, a nucleating agent, a temperature regulator, a gel monomer, a crosslinking agent, and an initiator, and heating the mixture in a water bath to obtain a mixed solution; S2, alternately layering the mixed solution and thermally conductive filler sheets, initiating polymerization using ultraviolet light, and then demolding to obtain a pre-material; S3. After vertically cutting the pre-material, a vertically oriented high thermal conductivity hydrated salt composite phase change gel material is obtained.

[0038] In the present invention, in step S1, the temperature of the water bath heating is 30-90°C, preferably 40-80°C, and more preferably 50-60°C.

[0039] In the present invention, in step S2, the ultraviolet light irradiation time is 1 to 60 minutes, preferably 10 to 50 minutes, and more preferably 20 to 40 minutes.

[0040] In the present invention, alternating layers of the mixed solution and thermally conductive filler sheets in step S2 facilitates precise control of the amount of hydrated salt gel added, ensuring uniform thickness between adjacent boron nitride sheets and avoiding delamination. By constructing a layered stacked structure, this material achieves directional thermal conductivity enhancement at a low thermally conductive filler content, while also combining high phase transition enthalpy and good mechanical stability, making it suitable for a variety of complex thermal management environments.

[0041] In the present invention, the alternating layers of the mixed solution and thermally conductive filler sheets in step S2 also partially trigger the curing of each layer of the hydrated salt gel under UV light, ensuring strong interlayer adhesion and uniform thickness. After stacking and curing, the sheets are cut perpendicularly along the arrangement direction of the thermally conductive filler sheets, ultimately forming a block structure material with directional heat conduction channels.

[0042] The present invention also provides the application of the vertically oriented high thermal conductivity hydrated salt composite phase change gel material in the field of thermal management.

[0043] The technical solutions provided by the present invention are described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0044] Example 1 (1) Weigh 81.5 parts of sodium acetate trihydrate, add it to a glass container, and heat and stir at 80°C until it becomes a solution; (2) Weigh 3.5 parts of urea, 14.0 parts of 2-acrylamido-2-methyl-1-propanesulfonic acid, and 0.5 parts of N,N′-methylenebisacrylamide into a glass container and stir in an 80°C water bath until the mixture becomes homogeneous and transparent. (3) Weigh 0.5 parts of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone, add it to a glass container, and stir in an 80°C water bath until the mixture becomes homogeneous and transparent; (4) In a mold measuring 5 cm × 5 cm × 1.2 cm, spread a layer of the above solution. Then, spread a layer of a 4.5 cm × 4.5 cm × 30 μm boron nitride sheet (each sheet weighs approximately 0.078 g). Then, spread another layer of the solution. Repeat this process until six boron nitride sheets have been added. Finally, spread another layer of the solution on top. Initiate polymerization using UV light for 1 min, and demold. (5) The pre-material obtained by demolding is weighed, and it is calculated that the boron nitride content in the block is 1 wt% at this time. After vertical cutting along the arrangement direction of the boron nitride sheets, the vertically oriented high thermal conductivity boron nitride doped hydrated salt composite phase change gel material is obtained.

[0045] Figure 2 This is a physical picture of the material obtained in this example.

[0046] Example 2 (1) Weigh 80.0 parts of ammonium aluminum sulfate dodecahydrate, add it to a glass container, and heat and stir at 90°C until it becomes a solution; (2) Weigh 2.4 parts of sodium chloride, 2.8 parts of disodium hydrogen phosphate dodecahydrate, 14.0 parts of acrylamide, and 0.4 parts of N,N′-methylenebisacrylamide, add them to a glass container, and stir in a 90°C water bath until the mixture is homogeneous and transparent; (3) Accurately weigh 0.4 parts of α-ketoglutaric acid, add it to a glass container, and stir in a 90°C water bath until it becomes homogeneous and transparent; (4) In a mold measuring 5 cm × 5 cm × 1.2 cm, spread a layer of the solution obtained above. Then, spread a layer of graphite film (single piece weighing approximately 0.281 g) measuring 4.5 cm × 4.5 cm × 0.07 mm. Then, spread another layer of the solution. Repeat this process until four graphite films have been added. Finally, spread another layer of the solution on top. Initiate polymerization using UV light for 1 min, and demold. (5) The demolded material (the graphite content in the material is 1 wt%) is cut vertically along the graphene arrangement direction to obtain the vertically oriented high thermal conductivity doped graphite hydrated salt composite phase change gel material.

[0047] Figure 3 This is a physical picture of the material obtained in this example.

[0048] Comparative Example 1 (1) Weigh 81.5 parts of sodium acetate trihydrate, add it to a glass container, and heat and stir at 80°C until it becomes a solution; (2) Weigh 3.5 parts of urea, 14.0 parts of 2-acrylamido-2-methyl-1-propanesulfonic acid, and 0.5 parts of N,N′-methylenebisacrylamide into a glass container and stir in an 80°C water bath until the mixture becomes homogeneous and transparent. (3) Weigh 0.5 parts of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone, add it to a glass container, and stir in an 80°C water bath until the mixture becomes homogeneous and transparent; (4) The above-obtained solution was poured into a mold of 5 cm × 5 cm × 1.2 cm in size, and polymerization was initiated by ultraviolet light irradiation for 1 min. The mold was then demolded to obtain the hydrated salt composite phase change gel material.

[0049] Figure 4 This is a physical picture of the material obtained in this comparative example.

[0050] Comparative Example 2 (1) Weigh 80.685 parts of sodium acetate trihydrate, add it to a glass container, and heat and stir at 80°C until it becomes a solution; (2) Weigh 3.465 parts of urea, 13.86 parts of 2-acrylamido-2-methyl-1-propanesulfonic acid, and 0.495 parts of N,N′-methylenebisacrylamide into a glass container and stir in an 80°C water bath until the mixture becomes homogeneous and transparent. (3) Weigh 0.495 parts of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone, add it to a glass container, and stir in an 80°C water bath until the mixture is homogeneous and transparent; (4) Accurately weigh 1 part of boron nitride powder, add it to a glass container, and stir in an 80°C water bath until uniform; (5) The above-obtained solution was poured into a mold of 5 cm×5 cm×0.2 cm in size, and polymerization was initiated by ultraviolet light irradiation for 10 min. The mold was then demolded to obtain the boron nitride powder-doped hydrated salt composite phase change gel material.

[0051] Figure 5 This is a physical picture of the material obtained in this comparative example.

[0052] Figure 6 This is a comparison diagram of the DSC curves of the boron nitride-doped hydrated salt gel composite phase change gel material obtained in Example 1 and the materials obtained in Comparative Examples 1 and 2; Figure 7 3. This is a comparison chart of the phase transition temperature and phase transition enthalpy values ​​of the boron nitride-doped hydrated salt gel composite phase change gel material obtained in Example 1 and the materials obtained in Comparative Examples 1 and 2; from Figure 6 and Figure 7 It can be seen that the boron nitride-doped method in Example 1 makes the phase change enthalpy of the material closer to that of the material in Comparative Example 1 without boron nitride doping, with a decrease of only 2.5%. In contrast, the phase change enthalpy of the material in Comparative Example 2, which adds boron nitride powder, differs significantly from that of the material in Comparative Example 1 without boron nitride doping, with a decrease of 11.8%. This is because adding boron nitride in a physical layered stacking method does not affect the phase change process of the phase change material hydrate salt in the material, while adding it in a powdered form may destroy the structure of the hydrated salt.

[0053] Figure 8 This is a comparison chart of the thermal conductivity of the boron nitride-doped hydrated salt gel composite phase change gel material obtained in Example 1 and the materials obtained in Comparative Examples 1 and 2.

[0054] from Figure 8 It can be seen that the radial thermal conductivity of the material doped with boron nitride in Example 1 is significantly improved by 118.5% compared to the material of Comparative Example 1 without boron nitride doping. In contrast, the radial thermal conductivity of the material of Comparative Example 2, which adds boron nitride powder, is similar to that of the material of Comparative Example 1 without boron nitride doping, with an increase of only 12.3%. This is because the addition of boron nitride in the material through physical layering and stacking allows the boron nitride in the material to be arranged in an efficient manner, forming a complete thermal conductivity path, while the addition of powder results in an incomplete thermal conductivity path between the boron nitrides, and also creates thermal resistance between fillers and between fillers and the matrix.

[0055] Comparative Example 3 (1) Weigh 80.0 parts of ammonium aluminum sulfate dodecahydrate, add it to a glass container, and heat and stir at 90°C until it becomes a solution; (2) Weigh 2.4 parts of sodium chloride, 2.8 parts of disodium hydrogen phosphate dodecahydrate, 14.0 parts of acrylamide, and 0.4 parts of N,N′-methylenebisacrylamide, add them to a glass container, and stir in a 90°C water bath until the mixture is homogeneous and transparent; (3) Weigh 0.4 parts of α-ketoglutaric acid, add it to a glass container, and stir in a 90°C water bath until it becomes homogeneous and transparent; (4) The above-obtained solution was poured into a mold of 5 cm × 5 cm × 0.8 cm in size, and polymerization was initiated by ultraviolet light irradiation for 1 min. The mold was then demolded to obtain the hydrated salt composite phase change gel material.

[0056] Figure 9 This is a physical picture of the material obtained in this comparative example.

[0057] Comparative Example 4 (1) Weigh 79.2 parts of ammonium aluminum sulfate dodecahydrate, add it to a glass container, and heat and stir at 90°C until it becomes a solution; (2) Weigh 2.376 parts of sodium chloride, 2.772 parts of disodium hydrogen phosphate dodecahydrate, 13.86 parts of acrylamide, and 0.396 parts of N,N′-methylenebisacrylamide, add them to a glass container, and stir in a 90°C water bath until the mixture is homogeneous and transparent; (3) Weigh 0.396 parts of α-ketoglutaric acid, add it to a glass container, and stir in a 90°C water bath until it becomes homogeneous and transparent; (4) Weigh 1 part of graphite powder, add it to a glass container, and stir in an 80°C water bath until it becomes uniform and transparent; (5) The above solution was poured into a mold of 5 cm × 5 cm × 1.2 cm in size, and polymerization was initiated by ultraviolet light irradiation for 10 min. The mold was then demolded to obtain the hydrated salt composite phase change gel material doped with graphite powder.

[0058] Figure 10 This is a physical picture of the material obtained in this comparative example.

[0059] Figure 11 This is a comparison diagram of the DSC curves of the graphite-doped hydrated salt gel composite phase change gel material obtained in Example 2 and the materials obtained in Comparative Examples 3 and 4; Figure 12 1 is a comparison chart of the phase change temperature and phase change enthalpy values ​​of the graphite-doped hydrated salt gel composite phase change gel material obtained in Example 2 and the materials obtained in Comparative Examples 3 and 4; from Figure 11 and Figure 12 It can be seen that the graphite doping method in Example 2 makes the phase change enthalpy of the material closer to that of the material in Comparative Example 3 without graphite doping, with a decrease of only 4.5%. In contrast, the phase change enthalpy of the material in Comparative Example 4, which adds graphite powder, differs significantly from that of the material in Comparative Example 3 without graphite doping, with a decrease of 30.1%. This is because adding graphite in a physical layered stacking method does not affect the phase change process of the phase change material hydrated salt in the material, while adding it in a powdered form may disrupt the structure of the hydrated salt.

[0060] Figure 13 This is a comparison chart of the thermal conductivity of the graphite-doped hydrated salt gel composite phase change gel material obtained in Example 2 and the materials obtained in Comparative Examples 3 and 4.

[0061] from Figure 13 It can be seen that the radial thermal conductivity of the material doped with graphite in Example 2 increased significantly by 431.6% compared to the material in Comparative Example 3, which did not have graphite doping. In contrast, the radial thermal conductivity of the material in Comparative Example 4, which added graphite powder, was comparable to that of the material in Comparative Example 3, which did not have graphite doping, only increasing by 52.6%. This is because the addition of graphite in a physical layered stacking method allows the graphite in the material to be efficiently arranged, forming a complete thermal conductivity path. Adding graphite in a powdered form results in an incomplete thermal conductivity path between the graphite particles, and also creates thermal resistance between the fillers and between the fillers and the matrix.

[0062] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A vertically oriented high thermal conductivity hydrated salt composite phase change gel material, characterized in that: The invention comprises the following raw materials in parts by weight: 10-30 parts of gel monomer, 0.03-0.5 parts of cross-linking agent, 0.005-0.5 parts of initiator, 0-5 parts of nucleating agent, 50-90 parts of hydrated salt, 0-10 parts of temperature regulator, and 0-5 parts of thermal conductive filler.

2. The vertically oriented high thermal conductivity hydrated salt composite phase change gel material according to claim 1, characterized in that: The gel monomer includes one or more of acrylamide, acrylic acid and 2-acrylamido-2-methyl-1-propanesulfonic acid; and the cross-linking agent includes N,N′-methylenebisacrylamide.

3. The vertically oriented high thermal conductivity hydrated salt composite phase change gel material according to claim 2, characterized in that: The initiator includes one or more of ammonium persulfate, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 1-hydroxy-cyclohexyl-phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, benzoin dimethyl ether, benzophenone, 2-isopropylthioxanthone, 4-isopropylthioxanthone, 2-methyl-1-(4-methylthiophenyl)-2-morpholinyl-1-propanone, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, 2-hydroxy-1-(4-(2-hydroxy-2-methylpropionylphenyl)benzyl)-2-methyl-1-propanone, 2,2-diethoxyacetylphenol, 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone and α-ketoglutaric acid.

4. The vertically oriented high thermal conductivity hydrated salt composite phase change gel material according to any one of claims 1 to 3, characterized in that: The nucleating agent includes one or more of disodium hydrogen phosphate dodecahydrate, sodium carbonate decahydrate, strontium chloride hexahydrate, barium hydroxide octahydrate, sodium silicate nonahydrate, sodium tetraborate decahydrate, sodium hexametaphosphate, calcium chloride dihydrate, sodium borate decahydrate and sodium pyrophosphate decahydrate.

5. The vertically oriented high thermal conductivity hydrated salt composite phase change gel material according to claim 4, characterized in that: The hydrated salt includes one or more of sodium acetate trihydrate, sodium sulfate decahydrate, sodium thiosulfate pentahydrate, calcium chloride hexahydrate, disodium hydrogen phosphate dodecahydrate, magnesium chloride hexahydrate, sodium carbonate decahydrate, zinc chloride tetrahydrate, sodium tetraborate decahydrate, magnesium acetate tetrahydrate, magnesium nitrate hexahydrate, calcium nitrate tetrahydrate, aluminum nitrate nonahydrate, zinc nitrate hexahydrate and ammonium aluminum sulfate dodecahydrate.

6. The vertically oriented high thermal conductivity hydrated salt composite phase change gel material according to claim 5, characterized in that: The temperature regulator includes one or more of urea, sodium chloride and potassium nitrate; The thermally conductive filler includes one or more of a boron nitride sheet, a graphite film, a polyethylene film, an aluminum nitride film, a silicon carbide film, polyimide, and a graphene film.

7. The method for preparing the vertically oriented high thermal conductivity hydrated salt composite phase change gel material according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1, mixing a hydrated salt, a nucleating agent, a temperature regulator, a gel monomer, a crosslinking agent, and an initiator, and heating the mixture in a water bath to obtain a mixed solution; S2, alternately layering the mixed solution and thermally conductive filler sheets, initiating polymerization using ultraviolet light, and then demolding to obtain a pre-material; S3. After vertically cutting the pre-material, a vertically oriented high thermal conductivity hydrated salt composite phase change gel material is obtained.

8. The preparation method according to claim 7, characterized in that In step S1, the water bath is heated at a temperature of 30-90°C.

9. The preparation method according to claim 8, characterized in that In step S2, the ultraviolet light irradiation time is 1 to 60 minutes.

10. Use of the vertically oriented high thermal conductivity hydrated salt composite phase change gel material according to any one of claims 1 to 6 in the field of thermal management.

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