Self-driven electrocaloric refrigeration film and device based on two-dimensional space confinement

Abstract

The invention discloses a self-driven electrocaloric refrigeration film and device based on a two-dimensional space confinement, belongs to the technical field of thermal management and solid-state refrigeration, and provides a film preparation method for improving electrocaloric effect cooling efficiency through a two-dimensional confinement template inducer and an action mechanism of the film preparation method. A two-dimensional confinement template inducer is adopted to guide an electrocaloric refrigeration polymer to adjust the molecular chain conformation on a two-dimensional plane under a spatial confinement condition; the discontinuous interaction formed by the porous structure of the two-dimensional confinement template inducer promotes the formation of a multi-site polar microstructure of the electrocaloric refrigeration polymer, increases the number of short-range polar domains of an electrocaloric refrigeration system and dipole entities responded by an electric field, and reduces the energy barrier in the phase change process under the driving of the electric field. The method is simple in preparation process, mild in reaction condition and low in cost, and the electrocaloric refrigeration device can achieve the refrigeration temperature of 5.4 K and electrodeformation of 2 mm in the vertical direction under the electric field of 70 MV / m. The invention provides a breakthrough innovative solution for the development of a new generation of efficient self-driven electric refrigeration devices.

Description

Technical Field

[0001] The present invention relates to the field of thermal management and solid-state refrigeration technology, and in particular to a preparation method and an action mechanism thereof for enhancing electrocaloric refrigeration effect by utilizing a two-dimensional confined template inducer. Background Art

[0002] With the rapid development of mobile devices and integrated circuit technology, the heat generated by high-integration, high-frequency 5G chips during operation has increased dramatically. If these instantaneous heat cannot be transferred and controlled in a timely and effective manner, microelectronic devices will fail due to overheating. Therefore, controlling the chip temperature within a safe operating range has become a key factor in ensuring the efficient operation of smart electronic devices. Traditional vapor compression cycle refrigeration technology faces the challenge of miniaturization difficulties, and the refrigerants such as hydrofluorocarbons it uses can cause environmental problems such as ozone layer depletion and greenhouse effect. In contrast, electric card refrigeration, as a new type of solid-state refrigeration technology, achieves cooling through the temperature change effect of ferroelectric materials under the action of an external electric field. This technology has significant advantages such as good flexibility, environmental protection, and easy miniaturization, providing an ideal solution to solving key technical problems such as current chip heat dissipation.

[0003] At present, the technical routes to improve the performance of electrocaloric materials mainly include: improving the degree of freedom of the system through the high entropy polarization conformation of electrocaloric materials; using doping to induce interface charge accumulation, energy traps, stress strain, optimize the phase change process and enhance dielectric properties (CN 105571196B, CN118638374A). However, in practical applications, the promotion of electrocaloric refrigeration technology is limited by thermal management capabilities, especially in terms of low thermal conductivity of materials and insufficient heat exchange efficiency. To solve this problem, researchers use thermally conductive fillers for passive heat dissipation to improve the stability of electrocaloric refrigeration materials during temperature changes, thereby achieving more efficient heat exchange and refrigeration effects.

[0004] Taking inorganic hexagonal boron nitride (BNNS) as an example, this typical two-dimensional thermal conductive material can significantly improve the heat transfer performance (CN 117164744A), but its highly ordered structure will clamp the electrocaloric effect of the composite material. In addition, the organic-inorganic heterogeneous phase interface is prone to performance mismatch, which further increases the challenges in material design. Therefore, compatibility must be improved in material optimization design (CN 117647027 A).

[0005] In response to the above challenges, the present invention proposes an innovative two-dimensional spatial confinement interface engineering method, which aims to improve the performance of electrocaloric cooling. Through the spatial confinement and porous structure of the two-dimensional confined template inducer, its interaction with the electrocaloric cooling polymer molecules is regulated to achieve effective regulation of the molecular chain conformation of the electrocaloric cooling polymer. This method not only significantly reduces the phase transition energy barrier during the electrocaloric cooling process, but also effectively enhances the performance of the electrocaloric effect. Unlike traditional methods, the two-dimensional confined template inducer forms a discontinuous interaction with the electrocaloric cooling polymer, promotes the formation of multi-site polar microstructures of the electrocaloric cooling polymer, increases the short-range polar domains of the system and the number of dipole entities that respond to the electric field, reduces the energy barrier of the electroinduced phase change process, and greatly reduces the energy required for electrocaloric cooling. Summary of the invention

[0006] The present invention provides a self-driven electrocaloric refrigeration film based on a two-dimensional confined template inducer and a preparation method thereof. The two-dimensional confined template inducer is innovatively used as a structural template inducer to regulate the molecular chain conformation of the electrocaloric cooling polymer on the two-dimensional plane through the two-dimensional spatial confinement effect. The two-dimensional porous confined template inducer induces the electrocaloric cooling polymer to form a multi-site polar microstructure, which significantly improves the short-range order and the number of dipole entities of the system, and effectively reduces the energy barrier of the electric field-driven phase transition process. At the same time, the vertical electrodeformation generated by the material during the electrocaloric effect has laid a key foundation for the development of energy-saving and environmentally friendly self-driven cooling technology.

[0007] In order to achieve the above-mentioned purpose, the technical solution of the present invention is as follows: a self-driven electrocaloric refrigeration film and device based on two-dimensional spatial confinement, by introducing a two-dimensional confined template inducer into an electrocaloric cooling polymer, a thin film material integrating electrocaloric refrigeration and electroinduced deformation is designed, and the film includes a two-dimensional confined template inducer and an electrocaloric cooling polymer.

[0008] A self-driven electric card refrigeration film based on two-dimensional space confinement, the method comprising the following steps:

[0009] Step 1: Synthesis of two-dimensional confined template inducer, i.e., synthesis of two-dimensional polyamide (2DPA)

[0010] 126 mg of melamine (1 equivalent) was dissolved in 9 mL of dimethylpyrrolidone, and 265 mg of trimesic acid trichloride (1 equivalent) and 1 mL of pyridine catalyst were added after ultrasonic dispersion for 10 minutes, and stirred at room temperature for 16 hours. The mixture was ultrasonicated in 80 mL of ethanol for 30 minutes, filtered, and washed with 80 mL of deionized water and 80 mL of acetone in sequence. Finally, it was vacuum dried at 100 ° C for 16 hours to obtain a light yellow two-dimensional polyamide powder with a molecular weight of about 37,000 and an average molecular size of about 15 nm.

[0011] Step 2: Preparation of two-dimensional space confined electrocaloric cooling film

[0012] 1-10wt% 2DPA was added to a 6%wt P(VDF-TrFE-CFE) organic solution and stirred for 12 hours until it was completely dissolved to form a clear and transparent solution. The resulting solution was subjected to 40kHz ultrasonic treatment for 30 minutes to 1 hour to ensure that the two-dimensional polyamide was evenly distributed in the electrocaloric cooling polymer matrix and to remove bubbles. The solution was drop-coated on a glass substrate and heat-treated at 50°C to 70°C for 12 hours to completely remove the residual solvent. The film was placed in ethanol for demolding and drying to obtain a uniform film with a thickness of about 30 microns.

[0013] Step 3: Construction of self-driven electro-cooling thin film device

[0014] Rectangular gold electrodes are deposited on both sides of the film by magnetron sputtering or vacuum electron deposition technology through a mask plate with a size of 8mm×36mm. The electrodes are connected by silver wires for applying an electric field, and the two ends are fixed with polyimide tape to achieve vertical electro-drive performance.

[0015] The two-dimensionally confined self-driven electrocaloric cooling film significantly improves the electric cooling capacity under low electric field under the action of template inducers.

[0016] As an improvement of the present invention, the physical characteristic of the two-dimensional confined template inducer is a two-dimensional structure containing macropores, and the pores of the two-dimensional structure can be regulated by the design and modification of the material. The material includes but is not limited to the following types: two-dimensional organic framework materials (COFs), two-dimensional metal organic frameworks (2D-MOFs), two-dimensional transition metal sulfides (TMDs), two-dimensional carbon materials (such as graphene derivatives), two-dimensional nitrides (such as modified boron nitride), and two-dimensional silicon-based materials.

[0017] As an improvement of the present invention, the chemical structure of the two-dimensional confined template inducer contains polar functional groups, and the polar functional groups include but are not limited to the combination of the following groups:

[0018] (1) Hydrogen bond donor groups: hydroxyl, carboxyl, amino, sulfhydryl, sulfonic acid, phosphate and phosphite;

[0019] (2) Hydrogen bond acceptor groups: aldehyde group, ketone group, ester group, ether group, amide group, imino group, and nitrile group;

[0020] (3) π-electron-rich groups: benzene ring, pyridine ring, furan ring, thiophene ring, pyrrole ring;

[0021] (4) Electron-withdrawing groups: nitro, carboxyl, and ester groups;

[0022] (5) Halogen groups: chlorine, bromine, fluorine, iodine.

[0023] As an improvement of the present invention, the two-dimensional confined template inducer forms a non-covalent interaction with the carbon-fluorine bond of the PVDF-based polymer, and the interaction does not affect the free movement ability of the carbon-fluorine bond under an electric field.

[0024] As an improvement of the present invention, the two-dimensional confined template inducer has a porous structure, which induces the PVDF-based polymer to form a dispersed, discontinuous polar conformation and micro-region.

[0025] As an improvement of the present invention, the two-dimensional confined template inducing agent has good compatibility with the PVDF-based polymer, which is manifested by one of the following characteristics: melting point, glass transition temperature, solubility parameter, surface energy or polarity, so that the membrane exhibits good structural uniformity at the microscopic and macroscopic scales.

[0026] As an improvement of the present invention, in the process of preparing the film, the co-solvent is selected from one of the polar organic solvents N,N-dimethylformamide and dimethyl sulfoxide, preferably N,N-dimethylformamide with a lower boiling point.

[0027] As an improvement of the present invention, the two-dimensional lamellar structure of the two-dimensional confined template inducer is obtained by one of the following preparation methods: vapor deposition, solution method, mechanical exfoliation, liquid exfoliation, atomic layer deposition, self-assembly method, in-situ polymerization method and supramolecular assembly, etc. In the present application, 2DPA is obtained by solution polymerization followed by self-assembly method.

[0028] As an improvement of the present invention, the interaction between the two-dimensional confined template inducer and the electrocaloric cooling polymer is achieved by the following methods: (1) Blending method: solution blending (similar solubility), melt blending (similar melting point), mechanical blending (similar polarity). (2) Layer-by-layer stacking method: LB film method, layer-by-layer spin coating method. In the present application, the interaction between the two is achieved by solution blending.

[0029] As an improvement of the present invention, the doping amount of the two-dimensional polyamide is 1-10wt%, preferably 1wt%. The film does not require a post-treatment process of high-temperature annealing.

[0030] The technical solution of the present invention:

[0031] 1. Material composition

[0032] (1) Electrocaloric cooling polymers, using materials with relaxor ferroelectric properties, such as vinylidene fluoride-trifluoroethylene-chlorovinylidene fluoride terpolymer P(VDF 64.6 -TrFE 26.2 -CFE 9.2 );

[0033] (2) A two-dimensional confined template inducing agent, which is a two-dimensional polyamide (2DPA) containing groups that can produce weak interactions with carbon-fluorine bonds, characterized by having multiple reactive groups such as benzene rings, C=O and NH;

[0034] (3) Doping ratio: the doping amount of the two-dimensional nanofiller is 1 to 10 wt %, preferably 1 wt %.

[0035] 2. Preparation method

[0036] Prepared by conventional solution casting method.

[0037] The polar organic solvent N,N-dimethylformamide (DMF) is preferably used as a co-solvent of the composite solution.

[0038] The preparation process can obtain a clear and transparent solution, and the film formation has no phase separation characteristics.

[0039] No high temperature annealing is required to regulate the crystal phase and crystallinity.

[0040] 3. Mechanism of action

[0041] By combining theoretical simulation with experiments, the regulation of molecular chain conformation by two-dimensional spatial confinement and weak intermolecular interactions was verified, and the energy barrier required for crystal phase transition was reduced. The electrostrictive effect of electrocaloric cooling polymers lays the foundation for the development of self-driven electric cooling devices.

[0042] Technical effects of the present invention:

[0043] The self-driven electric card refrigeration film developed by the present invention has the following significant advantages:

[0044] 1. Performance Improvement

[0045] The intrinsic polar molecular chain conformation of the electrocaloric polymer is improved by 30%, and the electrocaloric refrigeration performance is improved by 200%. Under a low electric field of 40MV / m, the cooling efficiency is doubled. At 60MV / m, the entropy change ΔS of the 10% 2DPA composite material is 24.2J / (kg·K), its electrocaloric strength (ΔS / ΔE) is 0.4(J·m) / (MV·kg·K), and the temperature change ΔT is 4.8K. Nearly 2mm of electroinduced deformation is achieved in the vertical direction.

[0046] 2. Structural characteristics

[0047] There are multiple short-range ordered polar conformations coexisting in the 2DPA composite film, and the proportion of polar conformations has increased by nearly one-third. Under the same electric field, the proportion of polar crystal phase of the electrocaloric cooling polymer P (VDF-TrFE-CFE) in the 10% 2DPA composite film is about 1.5 times that of the pure electrocaloric cooling polymer. In addition, at 60MV / m, the proportion of polar crystal phase in the electrocaloric cooling polymer is nearly 60%, which significantly reduces the driving energy barrier of the electrocaloric effect crystal phase transition.

[0048] In the above scheme, the two-dimensional confined template inducer introduces a new mechanism to improve the performance of electric refrigeration through spatial confinement, and the film exhibits an electro-induced deformation effect in the vertical direction, realizing synergistic drive in the electric refrigeration process. The two-dimensional material is used as a structural induction template, which is suitable for any material with a two-dimensional planar structure, not limited to two-dimensional polyamide, and induces the electrocaloric cooling polymer to regulate the molecular chain conformation on the two-dimensional plane through the two-dimensional confinement effect. The porous structure of the two-dimensional material is used to control the formation of short-range ordered rather than long-range ordered structures, thereby increasing the number of dipole entities under the electric field response and effectively improving the electrocaloric effect. The film also exhibits good compatibility, further enhancing the synergy and overall performance of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 Schematic diagram of the molecular interactions between two-dimensional polyamide and electrocaloric cooling polymer based on molecular dynamics simulation results.

[0050] Figure 2 Infrared spectroscopic characterization and semi-quantitative analysis of the conformational transition induced by two-dimensional polyamide.

[0051] Figure 3 Temperature-dependent dielectric frequency spectrum of a two-dimensional polyamide induced multiphase structure.

[0052] Figure 4 In situ wide-angle X-ray diffraction (WAXD) spectrum of electrocaloric cooling film under an applied electric field.

[0053] Figure 5 Electrocaloric properties of electrocaloric refrigeration films: isothermal entropy change (ΔS) and adiabatic temperature change (ΔT) characteristic curves.

[0054] Figure 6 Visual diagram of the self-driven electrocaloric effect synergistic integrated device. DETAILED DESCRIPTION

[0055] In order to deepen the understanding of the present invention, the present embodiment is described in detail below with reference to the accompanying drawings.

[0056] like Figure 1As shown, 2DPA effectively induces the electrocaloric cooling polymer to transform into a polar conformation through the structural template effect, thereby realizing the synergistic integration of electric refrigeration and electric drive, providing an important foundation for the development of energy-saving and environmentally friendly self-driven cooling technology.

[0057] Embodiment 1:

[0058] Theoretical simulation analysis of the interaction between electrocaloric cooling polymer and two-dimensional confined template inducer ( Figure 1 ):

[0059] In order to reveal the mechanism of 2DPA's influence on the molecular conformation of electrocaloric cooling polymers, density functional theory (DFT) simulation was used. In the process of geometry optimization, 2DPA was used as an environmental factor affecting the conformational change of electrocaloric cooling polymers. Findings:

[0060] 1. Under the action of two-dimensional spatial confinement and hydrogen bonding, 2DPA promotes the transformation of P(VDF-TrFE-CFE) to a polar conformation, and the terpolymer molecular chain extends along the two-dimensional framework.

[0061] 2. The porous structure causes the system to form a coexistence state of various polar microstructures, and the polar conformation sites formed are randomly distributed.

[0062] 3. As the polarity of the P(VDF-TrFE-CFE) molecular chain increases, the interaction between its polar conformation (TTTT or T3GT3G') and 2DPA becomes more stable.

[0063] Embodiment 2:

[0064] The preparation method of the two-dimensional space confined electric card refrigeration film has the following specific steps:

[0065] 1.2DPA was obtained by self-assembly after solution polycondensation: 126 mg of melamine (1 equivalent) was dissolved in 9 mL of dimethylpyrrolidone, and 265 mg of trimesic acid trichloride (1 equivalent) and 1 mL of pyridine catalyst were added after ultrasonic dispersion for 10 minutes, and stirred at room temperature for 16 hours. The mixture was ultrasonicated in 80 mL of ethanol for 30 minutes, filtered, and washed with 80 mL of deionized water and 80 mL of acetone in turn. Finally, it was vacuum dried at 100 ° C for 16 hours to obtain a light yellow two-dimensional polyamide powder with a molecular weight of about 37,000 and an average molecular size of about 15 nm.

[0066] 2. Solution preparation of two-dimensional confined electrocaloric film: The electrocaloric cooling polymer P (VDF-TrFE-CFE) powder was dissolved in N,N-dimethylformamide at a concentration of 6 wt%, and a certain amount of 2DPA was added to form 1%, 5%, and 10% complex solutions. The solution was stirred for 12 hours to obtain a clear and transparent complex solution, and then ultrasonically removed microbubbles.

[0067] 3. Film-forming process: The solution is filtered through a glass fiber syringe with a pore size of 0.7 μm, and the composite solution is slowly poured onto a 11 mm × 7 mm glass plate, and placed in an oven at 60°C for 12 hours until the solvent is completely evaporated. The film is obtained by ultrasonic peeling in anhydrous ethanol and dried for later use.

[0068] Embodiment 3:

[0069] Design and construction of self-driven electrocardial thin film devices: Using a designed mask (8mm×36mm), gold electrodes are deposited on the front and back of the film through the template by magnetron sputtering or electron beam evaporation. The electrodes are led out through silver wires for applying a field. When electrodriven in the vertical direction, the two ends of the film are fixed with polyimide tape.

[0070] Embodiment 4:

[0071] Performance characterization and mechanism analysis of self-driven electro-caloric refrigeration film based on two-dimensional space confinement:

[0072] 1. Molecular chain conformation change ( Figure 2 )

[0073] To reveal the effect of 2DPA on the conformational transition system, we compared the infrared spectra of P(VDF-TrFE-CFE) film and electrocaloric composite film containing 2DPA, and observed that the intensity of the non-polar TGTG' conformation-related peak was weakened, while the intensity of the polar T3GT3G' conformation peak was enhanced. The proportion of T3GT3G' conformation increased by 32.5% after the introduction of 2DPA.

[0074] 2. Dielectric properties ( Figure 3 )

[0075] Four different temperature peaks appear in the variable temperature dielectric spectra of P(VDF-TrFE-CFE) film and 2DPA composite film. These peaks do not change with frequency and exist simultaneously in the dielectric constant and loss spectra. The emergence of these microstructures is the result of 2DPA regulating the microenvironment in the P(VDF-TrFE-CFE) matrix. The increase in 2DPA content leads to the formation of many nanoscale polar phases, highlighting the multi-site polarity induction effect of two-dimensional polyamide and electrocaloric cooling polymer.

[0076] 3. Phase transition behavior ( Figure 4 )

[0077] In situ wide-angle X-ray diffraction (WAXD) tests show that the 2DPA electrocalin film induces an obvious polar phase peak (19.2°) at 40MV / m, which represents the electric field-induced polar phase (TTTT) conformation. Under the same electric field, the polar phase ratio of the 2DPA composite film is about 1.5 times that of P(VDF-TrFE-CFE). At 60MV / m, the polar phase accounts for nearly 60% and remains stable with the increase of the electric field. The easy transformation of the polar phase under low electric field originates from the induction of multi-site polar conformation, which acts as a polar crystal nucleus, reduces the energy required for the nucleation and growth of the polar phase under the electric field, and reduces the energy barrier required for phase transformation.

[0078] 4. Electrocaloric effect Figure 5 )

[0079] The electrocaloric effect (ECE) of the samples was characterized using an in-situ calibrated calorimetry system. The composite material containing 2DPA achieved a ΔS of 24.2 J / (kg·K) at 60 MV / m and a ΔT of 4.8 K, which is a 200% improvement over P(VDF-TrFE-CFE). The enhanced ECE at low electric fields is particularly beneficial, as it greatly alleviates the common electronic crosstalk problem in high electric field applications.

[0080] 5. Electrodeformable devices ( Figure 6 )

[0081] A deformation area with an effective active size of 8mm×36mm was designed. Under an electric field of 70MV / m, a vertical deformation of nearly 2mm was observed in the composite system, realizing self-driven electric refrigeration.

[0082] The present invention reveals the key mechanism of action of two-dimensional confined template inducers in self-driven electrocaloric refrigeration films. Two-dimensional confined template inducers can not only effectively induce electrocaloric cooling polymers to form multi-site polar microstructures and significantly reduce the phase change energy barrier, but also achieve excellent electrocaloric performance under low electric fields. Under the action of an electric field of 60MV / m, the electrocaloric refrigeration film showed significant performance improvement, with an entropy change ΔS of 24.2J / (kgK) and a temperature drop ΔT of 4.8K, while generating nearly 2mm of vertical electrodeformation. The present invention provides a breakthrough innovative solution for the development of a new generation of high-efficiency self-driven electric refrigeration devices.

[0083] It should be noted that the above specific implementation is only a preferred embodiment of the present invention and does not limit the scope of protection of the present invention. Any modification, supplement and substitution made by those skilled in the art without departing from the technical solution of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A self-driven electric card refrigeration film and device based on two-dimensional space confinement, characterized in that: The film introduces a two-dimensional confined template inducer into the electrocaloric cooling polymer to construct an integrated electrocaloric cooling system, which can simultaneously improve the performance of the electrocaloric cooling device and the electrodeformation performance.

2. The self-driven electric card refrigeration film based on two-dimensional space confinement according to claim 1 is characterized in that: The two-dimensional confined template inducer contains a macroporous two-dimensional structure, and the pores of the two-dimensional structure are regulated by the design and modification of the material. The material includes the following types: two-dimensional polyamide, two-dimensional organic framework material, two-dimensional metal organic framework, two-dimensional transition metal sulfide, two-dimensional carbon material, two-dimensional nitride, and two-dimensional silicon-based material.

3. The self-driven electric card refrigeration film based on two-dimensional space confinement according to claim 2 is characterized in that: The chemical structure of the two-dimensional confined template inducing agent contains polar functional groups, and the polar functional groups include one or more combinations of the following: (1) Hydrogen bond donor groups: hydroxyl, carboxyl, amino, sulfhydryl, sulfonic acid, phosphate and phosphite; (2) Hydrogen bond acceptor groups: aldehyde group, ketone group, ester group, ether group, amide group, imino group, and nitrile group; (3) π-electron-rich groups: benzene ring, pyridine ring, furan ring, thiophene ring, pyrrole ring; (4) Electron-withdrawing groups: nitro, carboxyl, and ester groups; (5) Halogen groups: chlorine, bromine, fluorine, iodine.

4. The self-driven electric card refrigeration film based on two-dimensional space confinement according to claim 2 is characterized in that: The two-dimensional confined template inducer forms a non-covalent interaction with the electrocaloric cooling polymer, and guides the electrocaloric cooling polymer to adjust the molecular chain conformation on a two-dimensional plane under spatial confinement conditions.

5. The self-driven electric card refrigeration film based on two-dimensional space confinement according to claim 2 is characterized in that: The porous structure of the two-dimensional confined template inducer forms a discontinuous interaction with the electrocaloric cooling polymer, promotes the formation of a multi-site polar microstructure of the electrocaloric cooling polymer, increases the number of short-range polar domains and electric field-responsive dipole entities in the system, reduces the energy barrier of the electrochemical phase change process, and greatly reduces the energy required for electrocaloric cooling.

6. The self-driven electric card refrigeration film based on two-dimensional space confinement according to claim 2 is characterized in that: The two-dimensional lamellar structure of the two-dimensional confined template inducer is obtained by one of the following preparation methods: in-situ polymerization self-assembly, vapor phase deposition, mechanical exfoliation, liquid phase exfoliation, atomic layer deposition and supramolecular assembly.

7. The self-driven electric card refrigeration film based on two-dimensional space confinement according to claim 6 is characterized in that: The two-dimensional confined template inducer was obtained by solution polymerization self-assembly method, and the specific implementation process was as follows: 126 mg of melamine (1 equivalent) was dissolved in 9 mL of dimethylpyrrolidone, and 265 mg of trimesic acid trichloride (1 equivalent) and 1 mL of pyridine catalyst were added after ultrasonic dispersion for 10 minutes, and stirred at room temperature for 16 hours. The resulting mixture was ultrasonicated in 80 mL of ethanol for 30 minutes, filtered, and washed with 80 mL of deionized water and 80 mL of acetone in turn, and finally vacuum dried at 100°C for 16 hours to obtain a light yellow two-dimensional polyamide powder with a molecular weight of about 37,000 and an average molecular size of about 15 nm.

8. The self-driven electric card refrigeration film based on two-dimensional space confinement according to claim 1 is characterized in that: The electrocaloric cooling polymer is a PVDF-based polymer, including P (VDF-TrFE-CFE) or its modified products, including polymer derivatives with electrocaloric cooling effect obtained by introducing or replacing other monomers or by chemical (grafting modification or surface modification) / physical methods (stretching orientation or annealing treatment).

9. The self-driven electric card refrigeration film based on two-dimensional space confinement according to claim 1 is characterized in that: The effect of the two-dimensional confined template inducer and the electrocaloric cooling polymer is achieved by the following method: (1) Blending method: solution blending (similar solubility), melt blending (similar melting point), mechanical blending (similar polarity); (2) Layer-by-layer stacking method: LB film method, layer-by-layer spin coating method. The preparation of the two-dimensional space confined electrocaloric refrigeration film is carried out by solution blending, and the specific implementation process is as follows: 1-10wt% of a two-dimensional confined template inducer is added to a 6%wt electrocaloric refrigeration polymer solution, and stirred for 12 hours until it is completely dissolved to form a clear and transparent solution. The resulting solution is subjected to 40kHz ultrasonic treatment for 30 minutes to 1 hour to ensure that the two-dimensional confined template inducer is evenly distributed in the electrocaloric refrigeration polymer matrix and to remove bubbles. The treated solution is drop-coated on a glass substrate, and heat-treated at 50°C to 70°C for 12 hours to completely remove the residual solvent. The film is placed in ethanol for demolding and drying without the need for high-temperature annealing process to obtain a uniform film with a thickness of about 30 microns.

10. The self-driven electric card refrigeration film based on two-dimensional space confinement according to claim 9, characterized in that: The two-dimensional confined template inducer and the electrocaloric polymer can be dissolved in the same organic solvent, wherein the polar solvent is one of N,N-dimethylformamide and dimethyl sulfoxide.

11. The self-driven electric card refrigeration film based on two-dimensional space confinement according to claim 1 is characterized in that: The construction of the self-driven electro-cooling device is specifically implemented as follows: rectangular gold electrodes are evaporated on both sides of the electro-cooling film through a mask plate using magnetron sputtering or vacuum evaporation methods. The mask plate size is 8mm×36mm. The electrodes are connected by silver wires for applying an external electric field, and the two ends are fixed with polyimide tape to achieve vertical electro-driven performance.

12. The self-driven electric card refrigeration film based on two-dimensional space confinement according to claim 11, characterized in that: The self-driven electro-caloric cooling device can achieve a cooling temperature of 5.4K and an electro-induced deformation of 2mm in the vertical direction under an electric field of 70MV / m.

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