An ionothermal electrocaloric gel material, a preparation method thereof and an electrocaloric device

Abstract

The application discloses an ionic thermoelectric gel material, a preparation method thereof and a thermoelectric device, and the preparation method comprises the following steps: adding a polysaccharide compound and a surfactant into water, stirring to obtain a mixed solution; heating and stirring the mixed solution for a preset time to obtain a sol; and cooling and shaping the sol to obtain the ionic thermoelectric gel material. The surfactant with an amphiphilic structure is used as a thermal diffusion subunit, and the hydrophobic ion in the surfactant is blocked in the gel matrix due to the strong hydrophobicity and the large ion size, so that the non-compensated diffusion of the anion and the cation is achieved, so that the ionic thermoelectric gel material has a high thermoelectric potential, and a giant thermoelectric potential effect of up to 43.1 mV·K ‑1 can be achieved. Compared with the electronic thermoelectric material, the ionic thermoelectric gel material with a high thermoelectric potential prepared by the application can obtain a high potential difference in a small temperature difference range, and is very suitable for room temperature application.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of thermoelectric materials, in particular to an ionic thermoelectric gel material, a preparation method thereof and a thermoelectric device. BACKGROUND

[0002] Internet of Things technology is the basis of smart life, and is widely used in animal tracking, process control, environmental protection, medical wearable devices and other scenes. At present, the power supply device of the sensor used in the Internet of Things technology still relies on the traditional battery, and the traditional battery has the problems of limited service life and complicated recycling steps. Thermoelectric materials and related devices can convert heat energy into electrical energy, and are expected to realize the collection and reuse of low-grade waste heat, so it is of great significance to develop thermoelectric materials with excellent performance.

[0003] Thermoelectric materials are divided into traditional electronic semiconductor thermoelectric materials and ionic thermoelectric materials. Electronic semiconductor thermoelectric materials have made remarkable development in the past few decades, and have obtained high thermoelectric figure of merit (ZT value) and thermoelectric conversion efficiency. However, limited by the theory of semiconductor thermoelectric transport, the Seebeck coefficient of electronic thermoelectric materials is maintained at about 200 μV·K -1 In order to obtain 1-5V voltage for the work of Internet of Things sensor, thousands or even tens of thousands of N-type and P-type thermoelectric pairs are needed under the condition of small temperature difference in room temperature environment, which greatly increases the integration difficulty and complexity of thermoelectric devices; or an external DC boost module is needed to further improve the voltage, but it will increase the power consumption and improve the use cost.

[0004] Therefore, the prior art still needs to be improved and developed. SUMMARY

[0005] In view of the above problems of the prior art, the purpose of the present application is to provide an ionic thermoelectric gel material, a preparation method thereof and a thermoelectric device, which aims to solve the problem that the Seebeck coefficient of the existing electronic thermoelectric material is small and the use is limited at room temperature.

[0006] The technical scheme of the present application is as follows:

[0007] In a first aspect of the present application, a preparation method of an ionic thermoelectric gel material is provided, which comprises the following steps:

[0008] A polysaccharide compound and a surfactant are added to water, and after stirring, a mixed solution is obtained;

[0009] The mixed solution is heated and stirred for a predetermined time to obtain a sol;

[0010] After the sol is cooled and shaped, the ionic thermoelectric gel material is obtained.

[0011] Optionally, the polysaccharide compound in the mixed solution has a mass percentage of 1-10%.

[0012] Optionally, the concentration of the surfactant in the mixed solution is 0.05–0.8 M.

[0013] Optionally, the polysaccharide compound is selected from at least one of agarose, chitosan, and carrageenan.

[0014] Optionally, the heating temperature is 85–100°C, and the preset time is 20–60 min.

[0015] Optionally, the surfactant is selected from anionic surfactants and cationic surfactants.

[0016] Optionally,

[0017] The anionic surfactant is selected from at least one of sulfonate anionic surfactants and sulfate anionic surfactants;

[0018] And / or, the cationic surfactant is selected from quaternary ammonium salt cationic surfactants.

[0019] Optionally, the sulfonate-type anionic surfactant is selected from at least one of sodium dodecylbenzenesulfonate, potassium trifluoromethylsulfonate, and potassium methanesulfonate;

[0020] And / or, the sulfate-type anionic surfactant is selected from sodium dodecyl sulfate;

[0021] And / or, the quaternary ammonium salt cationic surfactant is selected from dodecyltrimethylammonium bromide.

[0022] In a second aspect, the present invention provides an ion thermoelectric gel material, wherein the material is prepared by the preparation method described above.

[0023] In a third aspect, the present invention provides a thermoelectric device, wherein at least a portion of the thermoelectric device is prepared from the ion thermoelectric gel material of the present invention as described above.

[0024] Beneficial effects: This invention uses a surfactant (with an amphiphilic structure, containing both hydrophilic and hydrophobic ions) as a thermal diffusing agent. The surfactant acts as a thermal diffusion carrier in the ionothermal gel material. Due to their strong hydrophobicity and large ion size, the hydrophobic ions experience hindered diffusion within the gel matrix, leading to uncompensated diffusion of cations and anions. This results in a high thermoelectric potential and excellent thermoelectric performance in the ionothermal gel material, achieving a potential as high as 43.1 mV·K. -1The giant thermoelectric potential effect. Compared with electronic thermoelectric materials, the ionic thermoelectric gel material with high thermoelectric potential prepared by this invention can obtain a high potential difference within a small temperature range, making it very suitable for room temperature applications. Attached Figure Description

[0025] Figure 1 This is a flowchart illustrating the preparation process of the ion thermoelectric gel material in an embodiment of the present invention.

[0026] Figure 2 This is a schematic diagram of the thermoelectric device in an embodiment of the present invention.

[0027] Figure 3 This is a morphological diagram of the ion thermoelectric gel material in Example 1 of the present invention.

[0028] Figure 4 Images (a)-(d) are SEM images of the ion thermoelectric gel material in Example 1 of this invention at different magnifications.

[0029] Figure 5 The graph shows the thermoelectric potential test results of the ion thermoelectric gel material in Example 1 of the present invention.

[0030] Figure 6 The image shows the discharge test results of the ion thermoelectric gel material in Example 1 of this invention.

[0031] Figure 7 The graph shows the discharge power test results of the ion thermoelectric gel material under different resistance values ​​in Embodiment 1 of the present invention.

[0032] Figure 8 The graph shows the energy density test results of the ion thermoelectric gel material in Example 1 of this invention. Detailed Implementation

[0033] This invention provides an ion thermoelectric gel material and its preparation method. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below. It should be understood that the specific embodiments described herein are only for explaining this invention and are not intended to limit this invention.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0035] This invention provides a method for preparing an ion thermoelectric gel material, such as... Figure 1 As shown, the steps include:

[0036] S1. Add polysaccharide compounds and surfactants to water, stir, and obtain a mixed solution;

[0037] S2. The mixed solution is heated and stirred for a preset time to obtain a sol;

[0038] S3. After cooling and solidifying the sol, the ion thermoelectric gel material is obtained.

[0039] This invention employs a novel strategy to construct high-thermoelectric-potential ionic thermoelectric gel materials by inducing microporous morphology in polysaccharide gels using surfactants. Specifically, surfactants (with amphiphilic structures, containing both hydrophilic and hydrophobic ions) are used as thermal diffractors to enhance the thermoelectric potential and control the p- and n-type of the material. In other words, the surfactant acts as a thermal diffusion carrier in the ionic thermoelectric gel material. The strong hydrophobicity and large ion size of the hydrophobic ions hinder their diffusion within the gel matrix, leading to uncompensated diffusion of cations and anions. This results in ionic thermoelectric gel materials with high thermoelectric potential and high thermoelectric performance, achieving up to 43.1 mV·K. -1 The giant thermoelectric potential effect. Compared with electronic thermoelectric materials, the ionic thermoelectric gel material with high thermoelectric potential prepared in the embodiments of the present invention can obtain a high potential difference within a small temperature range, which is very suitable for room temperature applications.

[0040] Furthermore, in the preparation of ionothermal gel materials, surfactants act as structure-directing agents, inducing the formation of porous microstructures in the polysaccharide gel matrix. These porous microstructures restrict the diffusion of hydrophobic ions, decouple co-diffusion, and lead to a greater difference in the diffusion behavior of anions and cations, thus achieving non-compensated diffusion. Specifically, a sol is formed by heating a mixed solution. The sol has a certain viscosity, and during stirring, a large number of bubbles are generated. The hydrophobic ions of the surfactant aggregate around the bubbles, forming a micelle-like structure centered on the bubbles. After cooling to form a gel, the hydrophobic ions are confined within the porous morphology of the gel matrix, while the hydrophilic ions are unrestricted and uniformly distributed throughout the gel matrix.

[0041] In step S1, when the polysaccharide compound and surfactant are added to water and stirred to obtain a mixed solution, the mass percentage of the polysaccharide compound in the mixed solution is 1-10%.

[0042] In one embodiment, the concentration of the surfactant in the mixed solution is 0.05–0.8 M.

[0043] In one embodiment, the polysaccharide compound is selected from at least one of agarose, chitosan, and carrageenan, but is not limited thereto.

[0044] In one embodiment, the surfactant is selected from anionic surfactants and cationic surfactants. In this embodiment, different types of surfactants can be used to prepare different P-type and N-type ionic thermoelectric gel materials. Anionic surfactants can be used to prepare P-type ionic thermoelectric gel materials, and cationic surfactants can be used to prepare N-type ionic thermoelectric gel materials.

[0045] In one embodiment, the anionic surfactant is selected from at least one of sulfonate anionic surfactants and sulfate anionic surfactants, but is not limited thereto.

[0046] In one embodiment, the sulfonate-type anionic surfactant is selected from at least one of sodium dodecylbenzenesulfonate, potassium trifluoromethylsulfonate, and potassium methanesulfonate, but is not limited thereto.

[0047] In one embodiment, the sulfate-type anionic surfactant is selected from sodium dodecyl sulfate, but is not limited thereto.

[0048] In one embodiment, the cationic surfactant is selected from quaternary ammonium salt cationic surfactants, but is not limited thereto.

[0049] In one embodiment, the quaternary ammonium salt cationic surfactant is selected from, but is not limited to, dodecyltrimethylammonium bromide.

[0050] In step S2, in one embodiment, the heating temperature is 85–100°C, and the preset time is 20–60 minutes. For example, the heating temperature can be 85°C, 90°C, 95°C, or 100°C, and the preset time can be 20 minutes, 30 minutes, 40 minutes, 50 minutes, or 60 minutes.

[0051] In one embodiment, water bath heating can be used. Specifically, the mixed solution is heated in a water bath at 85–100°C and stirred for 20–60 minutes to obtain a sol;

[0052] In step S2, a sol is formed by heating the mixed solution. The sol has a certain viscosity. During stirring, the sol generates a large number of bubbles. The hydrophobic ions of the surfactant aggregate around the bubbles and form a micelle-like structure with the bubbles as the center. After subsequent cooling to form a gel, the hydrophobic ions are confined to the porous morphology region of the gel matrix, while the hydrophilic ions are unrestricted and uniformly distributed in the gel matrix. Therefore, the surfactant can act as a structure-directing agent to induce the formation of a porous microstructure in the polysaccharide gel matrix. The presence of these porous microstructures restricts the diffusion of hydrophobic ions, decouples co-directional diffusion, and leads to a greater difference in the diffusion behavior of anions and cations, achieving uncompensated diffusion and thus achieving a higher thermoelectric potential.

[0053] In step S3, the sol can be placed in a mold with a preset shape and cooled to form the ionothermal gel material. That is, the shape of the mold determines the shape of the ionothermal gel material. For example, the mold with the preset shape is a cubic polydimethylsiloxane mold.

[0054] This invention also provides an ionic thermoelectric gel material, which is prepared using the preparation method described above. The ionic thermoelectric gel material provided by this invention exhibits high thermoelectric potential and good thermoelectric performance. Compared to electronic thermoelectric materials, the ionic thermoelectric gel material prepared by this invention, with its high thermoelectric potential, can achieve a high potential difference within a small temperature range, making it highly suitable for room temperature applications. Furthermore, the ionic gel thermoelectric material prepared by this invention possesses excellent mechanical properties, allowing for appropriate design based on the application scenario, and holds great potential for powering hardware and wearable devices.

[0055] This invention also provides a thermoelectric device, wherein at least a portion of the thermoelectric device is prepared from the ion gel thermoelectric material described above in this invention. Specifically, as an example, such as... Figure 2 As shown, electrodes 2 are disposed at opposite ends of a cubic ion-gel thermoelectric material 1, constituting a simple thermoelectric device. Furthermore, the electrodes can be selected from metal foil or carbon electrodes, wherein the metal foil can be selected from gold foil, silver foil, or copper foil, etc.

[0056] The following detailed description uses specific examples.

[0057] Example 1

[0058] Add 0.7g sodium dodecylbenzenesulfonate and 1.4g agarose to 20mL of deionized water, and disperse evenly by ultrasonication to obtain a mixed solution;

[0059] The mixed solution was transferred into a water bath and stirred at 85°C for 45 minutes to obtain a sol.

[0060] The sol was transferred into a cubic polydimethylsiloxane mold and cooled to obtain an ionothermal gel material. Its morphology is shown in the figure below. Figure 3 As shown, it is a porous, opaque solid, and its scanning electron microscope image is as follows. Figure 4 As shown in (a)-(d), it can be seen that the ion thermoelectric gel material is a porous nanostructure formed by stacking layers.

[0061] Example 2

[0062] Add 0.28g sodium dodecylbenzenesulfonate and 0.7g agarose to 10mL of deionized water, and disperse evenly by ultrasonication to obtain a mixed solution;

[0063] The mixed solution was transferred into a water bath and stirred at 90°C for 30 minutes to obtain a sol.

[0064] The sol was transferred into a cubic polydimethylsiloxane mold and cooled to obtain an ion thermoelectric gel material.

[0065] Example 3

[0066] Add 0.6 g of dodecyltrimethylammonium bromide and 0.8 g of agarose to 10 mL of deionized water, and disperse evenly by ultrasonication to obtain a mixed solution;

[0067] The mixed solution was transferred into a water bath and stirred at 95°C for 50 minutes to obtain a sol.

[0068] The sol was transferred into a cubic polydimethylsiloxane mold and cooled to obtain an ion thermoelectric gel material.

[0069] Example 4

[0070] Add 0.2g of potassium trifluoromethanesulfonate and 0.8g of agarose to 10mL of deionized water, and disperse evenly by ultrasonication to obtain a mixed solution;

[0071] The mixed solution was transferred into a water bath and stirred at 90°C for 30 minutes to obtain a sol.

[0072] The sol was transferred into a cubic polydimethylsiloxane mold and cooled to obtain an ion thermoelectric gel material.

[0073] test:

[0074] (1) The thermoelectric potential of the ion thermoelectric gel material in Example 1 was tested, and the results are as follows: Figure 5 As shown, the three measurements were 43.1 mV·K. -1 41.8mV·K -1 and 39.2 mV·K -1 .

[0075] (2) Copper foil paper was placed at opposite ends as electrodes in a cubic polydimethylsiloxane mold. Then, the sol from Example 1 was added, cooled, and removed. The block-shaped ion thermoelectric gel material was sealed and compacted with plastic wrap to prepare a test device, such as... Figure 2 As shown, the battery reached saturation after 6 hours of charging, and was then discharged for 50 minutes. The discharge graph is shown below. Figure 6 As shown.

[0076] (3) Discharge the test device in (2) by loading it with resistors of 100KΩ, 200KΩ, 300KΩ, 400KΩ, and 500KΩ respectively. The discharge power diagram is shown below.Figure 7 As shown, the results indicate that the discharge power is highest when a 400KΩ resistor is applied.

[0077] (4) The energy density of the ion thermoelectric gel material prepared in Example 1 was tested, and the energy density graph is shown below. Figure 8 As shown, the highest energy density is 0.089 J·m. -2

[0078] (5) The thermoelectric potential of the ion thermoelectric gel materials in Examples 2, 3, and 4 was tested. The thermoelectric potential of the ion thermoelectric gel material in Example 2 reached 8 mV·K. -1 The thermoelectric potential of the ion thermoelectric gel material in Example 3 reaches -0.2 mV·K. -1 The thermoelectric potential of the ion thermoelectric gel material in Example 4 reaches 15 mV·K. -1 .

[0079] The test results above show that the thermoelectric potential of the ion thermoelectric gel material provided by this invention is as high as 43.1 mV·K. -1 It is an electronic thermoelectric material (Seebeck coefficient maintained at 200 μV·K). -1 It is more than 200 times larger than that of the left and right sides, and also has excellent thermoelectric properties.

[0080] In summary, this invention provides an ion thermoelectric gel material, its preparation method, and a thermoelectric device. This invention utilizes a surfactant (with an amphiphilic structure, containing both hydrophilic and hydrophobic ions) as a thermal diffusing agent. Specifically, the surfactant acts as a thermal diffusion carrier in the ion thermoelectric gel material. The hydrophobic ions, due to their strong hydrophobicity and large ion size, experience impeded diffusion within the gel matrix, leading to uncompensated diffusion of cations and anions. This results in a high thermoelectric potential and excellent thermoelectric performance in the ion thermoelectric gel material, achieving a potential as high as 43.1 mV·K. -1 The giant thermoelectric potential effect. Compared with electronic thermoelectric materials, the ionic thermoelectric gel material with high thermoelectric potential prepared by this invention can obtain a high potential difference within a small temperature range, making it very suitable for room temperature applications.

[0081] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A method for preparing an ionic pyroelectric gel material, characterized by, The preparation method comprises the steps of: adding a polysaccharide compound and a surfactant into water, stirring to obtain a mixed solution; heating and stirring the mixed solution for a preset time to obtain a sol; cooling and shaping the sol to obtain the ionic thermoelectric gel material; in the mixed solution, the mass percentage of the polysaccharide compound is 1-10%, and the concentration of the surfactant is 0.05-0.8M; the heating temperature is 85-100 DEG C, and the preset time is 20-60 min; the surfactant is sodium dodecyl benzene sulfonate; the polysaccharide compound is agarose.

2. An ionic pyroelectric gel material, characterized by, The ionic thermoelectric gel material is prepared by the preparation method in claim 1.

3. A thermoelectric device, characterized by, At least a part of the thermoelectric device is prepared from the ionic thermoelectric gel material in claim 2.

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