Preparation method and application of quasi-solid thermoelectric material capable of realizing humidity stability by means of phase separation regulation and control

Abstract

The invention belongs to the technical field of thermoelectricity, and relates to a preparation method and application of a quasi-solid thermoelectric material capable of realizing humidity stability by means of phase separation regulation, the preparation method comprises the following steps: dissolving a negatively charged hydrophilic monomer, an electrically neutral monomer, a cross-linking agent and a photoinitiator in a solvent to obtain a precursor solution, and carrying out an ultraviolet polymerization reaction to form polyelectrolyte gel; mixing the eutectic solvent with an electrolyte aqueous solution containing redox ion pairs and lithium chloride to obtain a quaternary electrolyte system; and immersing the gel into a quaternary electrolyte system, and fully replacing the internal solution through a diffusion effect to obtain the quasi-solid thermoelectric material with stable humidity. The thermoelectric material has the advantages of excellent Seebeck coefficient, good stability, high mechanical strength, large power density and the like, can supply power to wearable electronic products in an actual humidity fluctuation environment, breaks through the main bottleneck of actual application of quasi-solid ionic thermoelectric materials based on ionized water gel, and is wide in application prospect.

Description

Technical Field

[0001] This invention belongs to the field of thermoelectric technology, and particularly relates to wearable quasi-solid flexible thermoelectric materials. Specifically, it relates to a method for preparing wearable quasi-solid thermoelectric materials that achieve humidity stability by relying on phase separation regulation, and its application. Background Technology

[0002] Wearable quasi-solid-state ionic thermoelectric materials based on ion hydrogels combine the superior Seebeck coefficient and strong structural stability of liquid-phase ionic thermal batteries, and effectively alleviate electrolyte leakage problems, making quasi-solid-state ionic thermoelectric materials a promising sustainable energy source for future wearable electronic devices and IoT devices. However, traditional quasi-solid-state ionic thermoelectric materials based on ion hydrogels have significant limitations in their ability to regulate moisture in the environment. In low-humidity environments, dehydration leads to a significant degradation in properties such as flexibility, ionic conductivity, and power output; in high-humidity environments, excessive swelling causes severe deterioration in mechanical and thermoelectric properties. Currently, encapsulation methods can effectively stabilize the water content in quasi-solid-state thermoelectric materials, but this leads to problems such as decreased heat transfer efficiency, increased encapsulation process complexity, and poor compatibility at the electrode / encapsulation material interface.

[0003] To address these issues, researchers have primarily focused on enhancing water absorption by introducing hygroscopic salts and non-volatile hydrophilic additives to mitigate dehydration in ion-hydrogel quasi-solid-state thermoelectric materials under low humidity conditions. However, these modified hydrogels still exhibit significant fluctuations in water content due to changes in ambient humidity. In low-humidity environments, the increased physical cross-linking density within the gel network due to enhanced chain entanglement and supramolecular interactions accelerates the dehydration process. Conversely, in high-humidity environments, the density of inter-chain physical cross-linking decreases, leading to excessive swelling. The difficulty in maintaining a suitable and stable water content under varying ambient humidity levels is a major obstacle to achieving efficient thermoelectric conversion in real-world fluctuating humidity environments using ion-hydrogel-based quasi-solid-state ion-hydrogel thermoelectric materials. Summary of the Invention

[0004] To overcome the problems existing in the prior art, this invention provides a method for preparing a quasi-solid-state thermoelectric material with humidity stability achieved by phase separation regulation, and the resulting humidity-stable quasi-solid-state thermoelectric material. By preparing a humidity-induced phase separation hydrogel matrix, the degree of phase separation is synergistically regulated by the components within the gel under different humidity environments. This avoids the problem of significant changes in water content in quasi-solid-state thermoelectric materials caused by the introduction of hygroscopic salts and non-volatile hydrophilic additives in current methods for developing quasi-solid-state thermoelectric materials. Furthermore, this invention endows the quasi-solid-state thermoelectric material with excellent Seebeck coefficient, good stability, high mechanical strength, and high power density, enabling it to power wearable electronic products in environments with fluctuating humidity. This breakthrough overcomes the main bottleneck in the practical application of quasi-solid-state ionic thermoelectric materials based on ionic hydrogels, and has broad application prospects.

[0005] To achieve the above objectives, this invention provides a method for preparing a quasi-solid thermoelectric material that achieves humidity stability through phase separation control, the specific steps of which include:

[0006] (1) Dissolve negatively charged hydrophilic monomers, electrically neutral monomers, crosslinking agents and photoinitiators in a solvent to obtain precursor solution A, and then carry out ultraviolet light polymerization reaction to form polyelectrolyte gel;

[0007] (2) A quaternary electrolyte system is obtained by mixing a eutectic solvent and an aqueous electrolyte containing redox ion pairs and lithium chloride.

[0008] (3) The gel obtained in step (1) is immersed in the quaternary electrolyte system in step (2) and the internal solution is fully replaced by diffusion to obtain a quasi-solid thermoelectric material with stable humidity.

[0009] In a further preferred embodiment, the negatively charged hydrophilic monomer is selected from monomers containing sulfonate ions, preferably acrylic acid and its derivatives containing sulfonate ions, preferably 2-acrylamido-2-methylpropanesulfonic acid (AMPS), and more preferably potassium 3-sulfopropylacrylate (SPAK).

[0010] In a preferred embodiment, the electrically neutral monomer in step (1) is acrylamide or an electrically neutral monomer containing a benzene ring hydrophobic group.

[0011] In a further preferred embodiment, the electrically neutral monomer containing a benzene ring hydrophobic group is selected from phenyl acrylates, preferably 2-phenoxyethyl acrylate.

[0012] In a further preferred embodiment, the solvent in step (1) is an organic solvent or deionized water, preferably dimethyl sulfoxide; the crosslinking agent is N',N'-methylenebisacrylamide; and the photoinitiator is α-ketoglutaric acid.

[0013] In a preferred embodiment, in step (1), the total concentration of negatively charged hydrophilic monomers and electrically neutral monomers in precursor solution A is 20-50 wt%, preferably 25-35 wt%, for example 25 wt%, 30 wt% or 35 wt%.

[0014] In a preferred embodiment, in step (1), the molar ratio of negatively charged hydrophilic monomers and electrically neutral monomers in precursor solution A is 3:1 to 1:3, preferably 2:1 to 1:2, for example 2:1, 1:1 or 1:2.

[0015] In a preferred embodiment, in step (1), the amount of crosslinking agent added is 0.5 to 1 wt% of the total amount of negatively charged hydrophilic monomers and electrically neutral monomers, preferably 0.7 to 0.8 wt%, for example 0.7 wt%, 0.75 wt% or 0.8 wt%.

[0016] In a preferred embodiment, in step (1), the amount of photoinitiator added is 0.1 to 0.5 wt% of the total amount of negatively charged hydrophilic monomers and electrically neutral monomers, preferably 0.2 to 0.3 wt%, for example 0.2 wt%, 0.25 wt% or 0.3 wt%.

[0017] In a preferred embodiment, in step (1), the specific preparation process of the precursor solution A is as follows: a negatively charged hydrophilic monomer, an electrically neutral monomer, a crosslinking agent and a photoinitiator are added to a solvent, first magnetically stirred and dispersed for 5 minutes, and then ultrasonically treated for 10 minutes to ensure that the monomers are completely dissolved; then magnetically stirred for another 5 minutes to obtain a uniform mixed solution; the solution is allowed to stand for 5 minutes to degas at room temperature to obtain the precursor solution A.

[0018] In a preferred embodiment, in step (1), the precursor solution A is injected into a mold and then subjected to ultraviolet light polymerization reaction. The mold consists of two soda-lime glass slides and a hollow silicone gasket. The thickness of the hollow silicone gasket is 0.5~4mm, preferably 1.5~2.5mm, for example, 1.5mm, 2mm or 2.5mm.

[0019] In a preferred embodiment, in step (1), the ultraviolet light wavelength is 365 nm; the polymerization time is 2-6 h. Preferably, the polymerization time is 4-6 h. For example, the polymerization time is 4 h, 4.5 h, 5 h, 5.5 h, or 6 h.

[0020] In a preferred embodiment, in step (2), the eutectic solvent is preferably a choline chloride-glycerol mixture, with a molar ratio of choline chloride to glycerol of 1:1 to 1:3, more preferably 1:1 to 1:2. Regarding hygroscopicity, both choline chloride and glycerol are hygroscopic salts / organic compounds, which can provide water retention properties for the quasi-solid thermoelectric material in low-humidity environments. Furthermore, the addition of glycerol further enhances the stability of the quasi-solid thermoelectric material, ensuring its long-term use.

[0021] In a preferred embodiment, in step (2), the redox ion pair is preferably potassium ferricyanide and potassium ferrocyanide.

[0022] Specifically, the redox ion pair needs to be stable in the solution system, not undergo disproportionation reactions, not precipitate during the redox reaction, and not interact strongly with the gel matrix to restrict ion movement within the network. Furthermore, as a wearable flexible thermoelectric material, it cannot have high biotoxicity. Therefore, potassium ferrocyanide / potassium ferrocyanide ion pairs that simultaneously meet the above conditions and exhibit a large entropy change during redox reactions are preferred.

[0023] In a preferred embodiment, in step (2), the concentration of redox ion pairs in the electrolyte aqueous solution is 0.2M~0.4M, and the LiCl mass concentration is 10wt%~30wt%; preferably, the concentration of redox ion pairs is 0.3M~0.4M, and the LiCl mass concentration is 20wt%~30wt%.

[0024] In a preferred embodiment, in step (2), the content of the eutectic solvent is 50-95 wt% based on 100 wt% of the weight of the quaternary electrolyte system, and the content of the electrolyte aqueous solution is 5-50 wt%.

[0025] For example, in step (2), based on 100 wt% of the weight of the quaternary electrolyte system, the eutectic solvent system accounts for 50 wt%, 75 wt%, 90 wt%, 95 wt%, and the electrolyte aqueous solution system accounts for 5 wt%, 10 wt%, 25 wt%, or 50 wt%.

[0026] In a preferred embodiment, the replacement process in step (3) takes 48 hours.

[0027] This invention achieves humidity stability in thermoelectric materials by introducing a quaternary electrolyte through diffusion within a polyelectrolyte gel. The humidity stability is further enhanced when a neutral monomer containing a benzene ring hydrophobic group is used. This is because: the use of a negatively charged hydrophilic monomer during polyelectrolyte gel preparation creates negatively charged ion channels within the gel, which helps increase the entropy difference in the diffusion of redox ion pairs (preferably potassium ferrocyanide / potassium ferrocyanide ion pairs) within the material, thereby improving thermoelectric output; and the amphiphilic polyelectrolyte gel prepared using a negatively charged hydrophilic monomer and a neutral monomer containing a benzene ring hydrophobic group allows the hydrophobic phenyl groups to diffuse through the gel as the internal water content increases. - Interactions induce microphase separation, thereby enhancing the physical crosslinking density, effectively hindering excessive moisture absorption under high humidity conditions, and suppressing the degradation of mechanical and thermoelectric conversion performance of quasi-solid thermoelectric materials under high humidity. Furthermore, the redox ion pairs interact with the ions between the benzene rings... The interaction also helps to increase the entropy difference in the diffusion of redox ion pairs in the material, thereby improving thermoelectric output.

[0028] In this invention, after extensive experimental research, the inventors discovered that by constructing a charged gel matrix using negatively charged hydrophilic monomers and electrically neutral monomers, and introducing a water-absorbing quaternary electrolyte system through diffusion, stable power generation of the quasi-solid thermoelectric material in different environments can be achieved through the synergistic regulation of the internal components of the material in environments with varying humidity. The reason is that in low humidity environments, the reduction in water content within the material reduces internal microphase separation and decreases the density of physical crosslinking, thereby reducing the hydrochemical potential within the material and effectively promoting the absorption of moisture by the internal hygroscopic components in low humidity environments, ultimately avoiding the degradation of the quasi-solid thermoelectric material in terms of flexibility and thermoelectric conversion performance. When the electrically neutral monomer is a monomer containing a benzene ring hydrophobic group, the prepared thermoelectric material has stronger humidity stability because (1) when the humidity increases, the hydrophobic phenyl group passes through the benzene ring hydrophobic group. - The interaction induces microphase separation and enhances the physical crosslinking density, thereby increasing the hydrochemical potential within the material, effectively hindering the excessive absorption of water under high humidity conditions, and ultimately suppressing the degradation of the quasi-solid thermoelectric material in terms of mechanical properties and thermoelectric conversion performance; (2) During the diffusion process of potassium ferrocyanide / potassium ferrocyanide ion pairs under the action of temperature gradient on both sides of the material, they are subjected to electrostatic interaction of sulfonate ions and ion- of benzene rings. The dual effects of the interaction further increase the entropy difference between redox ion pairs, which helps to achieve high-level thermoelectric output.

[0029] The present invention also provides thermoelectric materials obtained by the preparation method described above.

[0030] The present invention also provides the application of the thermoelectric material in wearable materials.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] (1) The thermoelectric material obtained by the preparation method described in this invention has stronger environmental adaptability and can maintain a continuous and stable high level of output in the unencapsulated state;

[0033] (2) The preparation method described in this invention is simple, green and environmentally friendly, and low in cost. The preparation process is simple and easy to carry out industrial production.

[0034] In summary, the quasi-solid thermoelectric material prepared by this invention is humidity-stable and can maintain a suitable and stable water content in varying environmental humidity. It can achieve efficient thermoelectric conversion in actual fluctuating humidity environments and has advantages such as excellent Seebeck coefficient, good stability, high mechanical strength, and high power density. It can power wearable electronic products in actual humidity fluctuating environments and has broad application prospects. Attached Figure Description

[0035] Figure 1 The diagram illustrates the changes in water content under different humidity levels for traditional AM / AMPS ion hydrogel thermoelectric materials and the SPAK / PEA humidity-stable quasi-solid thermoelectric material of this invention.

[0036] Figure 2 The output power density curves of SPAK / PEA humidity-stable thermoelectric material under different humidity environments with an external resistor connected at a temperature difference of 10°C.

[0037] Figure 3 The output power density curves of the AMPS / AM humidity-stable thermoelectric material under different humidity environments with an external resistor connected at a temperature difference of 10°C are shown.

[0038] Figure 4 The output power density curves of the SPAK / PEA conventional thermoelectric material under different humidity environments with an external resistor connected at a temperature difference of 10°C.

[0039] Figure 5 The output power density curves of the AMPS / AM conventional thermoelectric material under different humidity environments with an external resistor connected at a temperature difference of 10°C.

[0040] Figure 6 The variation of internal water content in humidity-stable thermoelectric materials prepared for different gel monomers (AMPS / AM or SPAK / PEA) under different humidity environments.

[0041] Figure 7 The Seebeck coefficient of humidity-stable thermoelectric materials prepared for different gel monomers (AMPS / AM or SPAK / PEA) varies under different humidity environments.

[0042] Figure 8 The variation of water content in conventional hydrogel thermoelectric materials prepared for different gel monomers (AMPS / AM or SPAK / PEA) under different humidity environments.

[0043] Figure 9 The Seebeck coefficient of conventional hydrogel thermoelectric materials prepared for different gel monomers (AMPS / AM or SPAK / PEA) varies under different humidity environments.

[0044] Figure 10 The effect of different eutectic solvent concentrations on the Seebeck coefficient of the humidity-stable SPAK / PEA thermoelectric material in a quaternary electrolyte system.

[0045] Figure 11 The effect of different monomer ratios on the Seebeck coefficient of the humidity-stable thermoelectric material SPAK / PEA.

[0046] Figure 12 The effect of different redox ion pair concentrations in a quaternary electrolyte system on the Seebeck coefficient of the humidity-stable thermoelectric material SPAK / PEA. Detailed Implementation

[0047] The present invention will now be described in detail with reference to specific embodiments and accompanying drawings. It should be noted that the following embodiments are only for further illustration of the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.

[0048] Unless otherwise specified, the raw materials used in the examples and comparative examples are all disclosed in the prior art, such as those that can be directly purchased or prepared according to the preparation methods disclosed in the prior art.

[0049] Example 1

[0050] This embodiment relates to a method for preparing a quasi-solid thermoelectric material that achieves humidity stability through phase separation control. The specific steps are as follows:

[0051] (1) Preparation of amphiphilic polyelectrolyte gel

[0052] (1.1) The negatively charged hydrophilic monomer 3-sulfopropyl acrylate potassium (SPAK), the electrically neutral hydrophobic monomer 2-phenoxyethyl acrylate (PEA), N',N'-methylenebisacrylamide crosslinking agent, and α-ketoglutaric acid photoinitiator were added to dimethyl sulfoxide and magnetically stirred for 5 minutes. The mixture was then sonicated for 10 minutes to ensure complete dissolution of the monomers. Magnetic stirring was then continued for 5 minutes to obtain a homogeneous mixture. The mixture was allowed to stand at room temperature for 5 minutes to degas, yielding precursor solution A. The total amount of hydrophilic and hydrophobic monomers in precursor solution A was 30 wt%, the amount of N',N'-methylenebisacrylamide added was 0.75 wt% of the total amount of hydrophilic and hydrophobic monomers, and the amount of α-ketoglutaric acid added was 0.25 wt% of the total amount of hydrophilic and hydrophobic monomers. The molar ratio of the hydrophilic and hydrophobic monomers was 1:2.

[0053] (1.2) The prepared precursor solution A was injected into a mold consisting of two soda-lime glass slides (separated by a 2 mm thick hollow silicone gasket) to obtain sample B;

[0054] (1.3) Sample B was placed in an ultraviolet box and polymerized under 365nm ultraviolet light for 4h to obtain an amphiphilic polyelectrolyte gel;

[0055] (2) Preparation of quaternary electrolyte system

[0056] (2.1) A eutectic solvent was prepared by mixing choline chloride and glycerol in a molar ratio of 1:2 and heating and stirring at 60°C for 1 h.

[0057] (2.2) Add redox ion pairs and LiCl to deionized water and stir to dissolve to prepare an electrolyte aqueous solution, wherein the concentration of redox ion pairs in the electrolyte aqueous solution is 0.4M and the mass concentration of LiCl is 2.5wt%; the redox ion pairs are potassium ferricyanide and potassium ferrocyanide, and the molar ratio of the two is 1:1;

[0058] (2.3) Mix the eutectic solvent and the electrolyte aqueous solution at a weight ratio of 90:10 (100wt% by weight), stir to dissolve, and obtain a quaternary electrolyte system;

[0059] (3) Preparation of humidity-stable quasi-solid thermoelectric materials

[0060] Immersing amphiphilic polyelectrolyte gel in a quaternary electrolyte system for 48 hours yields a moisture-stable quasi-solid thermoelectric material (also known as SPAK / PEA moisture-stable thermoelectric material).

[0061] The obtained humidity-stable quasi-solid thermoelectric material was tested for its electrical properties and humidity stability under a 10℃ temperature difference. The results are as follows: Figure 2 , Figure 6 and Figure 7As shown. From Figure 2 , Figure 6 and Figure 7 It can be seen that at 30% humidity, its output power density can reach a maximum of 18.54 mW / m³. 2 The Seebeck coefficient is 2.17 mV / K, and the internal moisture content is stable at 33.6 wt%. At 99% humidity, the highest output power density can reach 54.81 mW / m³. 2 The Seebeck coefficient is 1.63 mV / K, and the internal moisture content remains stable at 60.3 wt%. This indicates that the internal moisture content of the material does not change significantly within a humidity range of 30%-99%.

[0062] Example 2

[0063] This embodiment relates to a method for preparing a quasi-solid thermoelectric material with humidity stability achieved by phase separation control. The difference from Example 1 is that the monomers used to prepare the humidity-stable quasi-solid thermoelectric material are the negatively charged monomer 2-acrylamido-2-methylpropanesulfonic acid (AMPS) and the electrically neutral monomer acrylamide (AM), and deionized water is used as the solvent. The humidity-stable quasi-solid thermoelectric material (also called AMPS / AM humidity-stable thermoelectric material) is prepared according to the preparation method of Example 1 with other conditions unchanged.

[0064] The obtained humidity-stable wearable quasi-solid thermoelectric material was tested for its electrical properties and humidity stability under a 10℃ temperature difference. The results are as follows: Figure 3 , Figure 6 and Figure 7 As shown. From Figure 3 , Figure 6 and Figure 7 It can be seen that at 30% humidity, its output power density can reach a maximum of 4.84 mW / m. 2 The Seebeck coefficient is 1.66 mV / K, and the internal moisture content is stable at 13.86 wt%. At 99% humidity, the maximum output power density can reach 23.14 mW / m³. 2 The Seebeck coefficient is 0.986 mV / K, and the internal water content is stable at 75.3 wt%.

[0065] Example 3

[0066] This example demonstrates the effect of different eutectic solvent concentrations on the Seebeck coefficient of a humidity-stable SPAK / PEA thermoelectric material. Following the preparation method of Example 1, the mixing ratio of the eutectic solvent and electrolyte water was varied, resulting in eutectic solvent concentrations of 50 wt%, 75 wt%, 90 wt%, and 95 wt% in the quaternary electrolyte system, thus preparing different humidity-stable quasi-solid-state SPAK / PEA thermoelectric materials.

[0067] The Seebeck coefficient of the obtained humidity-stable quasi-solid thermoelectric material was measured under a temperature difference of 10 °C, and the results are as follows: Figure 10 As shown. From Figure 10 It can be seen that the Seebeck coefficient is 1.93 when the concentration of the eutectic solvent in the quaternary electrolyte system is 50 wt%, 2.07 when the concentration of the eutectic solvent in the quaternary electrolyte system is 75 wt%, 2.17 when the concentration of the eutectic solvent in the quaternary electrolyte system is 90 wt%, and 1.97 when the concentration of the eutectic solvent in the quaternary electrolyte system is 95 wt%.

[0068] Example 4

[0069] This embodiment involves an experiment on the effect of different monomer ratios on the Seebeck coefficient of the SPAK / PEA humidity-stable thermoelectric material.

[0070] Following the method of Example 1, the molar ratios of the negatively charged hydrophilic monomer potassium 3-sulfopropyl acrylate (SPAK) and the benzene ring-containing hydrophobic monomer 2-phenoxyethyl acrylate (PEA) in step (1.1) were changed to 1:1, 2:3, 1:2, 2:5 and 1:3, respectively, while other conditions remained unchanged, to prepare different SPAK / PEA humidity-stable thermoelectric materials.

[0071] The Seebeck coefficient of the obtained humidity-stable quasi-solid thermoelectric material was measured under a temperature difference of 10 °C, and the results are as follows: Figure 11 As shown. From Figure 11 It can be seen that when the SPAK / PEA ratio is 1:1, the Seebeck coefficient is 1.67; when the SPAK / PEA ratio is 2:3, the Seebeck coefficient is 1.81; when the SPAK / PEA ratio is 1:2, the Seebeck coefficient is 2.17; when the SPAK / PEA ratio is 2:5, the Seebeck coefficient is 1.96; and when the SPAK / PEA ratio is 1:3, the Seebeck coefficient is 1.63.

[0072] Example 5

[0073] This embodiment relates to an experiment on the effect of different redox ion concentrations in a quaternary electrolyte system on the Seebeck coefficient of a humidity-stable quasi-solid thermoelectric material.

[0074] Following the preparation method of Example 1, the amount of redox ion pairs used in step (2.2) was changed so that the concentrations of redox ion pairs in the electrolyte aqueous solution were 0.2M, 0.3M, 0.4M and 0.5M, respectively, while other conditions remained unchanged.

[0075] The Seebeck coefficient of the obtained SPAK / PEA humidity-stable wearable quasi-solid thermoelectric material was measured under a 10°C temperature difference, and the results are as follows: Figure 12 As shown. From Figure 12 It can be seen that when the concentration of redox ion pairs is 0.2M, the Seebeck coefficient is 1.81; when the concentration of redox ion pairs is 0.3M, the Seebeck coefficient is 1.92; when the concentration of redox ion pairs is 0.4M, the Seebeck coefficient is 2.17; and when the concentration of redox ion pairs is 0.5M, the Seebeck coefficient is 1.65.

[0076] Comparative Example 1

[0077] This comparative example involves the preparation of a traditional SPAK / PEA hydrogel thermoelectric material, and the specific steps are as follows:

[0078] (1) Preparation of amphiphilic polyelectrolyte gel: The hydrophilic monomer 3-sulfopropyl acrylate and the hydrophobic monomer 2-phenoxyethyl acrylate, along with N',N'-methylenebisacrylamide crosslinking agent and α-ketoglutaric acid photoinitiator, were added to dimethyl sulfoxide organic solvent and magnetically stirred for 5 minutes. The mixture was then sonicated for 10 minutes to ensure complete dissolution of the monomers. Magnetic stirring was continued for another 5 minutes to obtain a homogeneous mixture. The mixture was allowed to stand at room temperature for 5 minutes to degas, yielding precursor solution A. The total amount of hydrophilic and hydrophobic monomers in precursor solution A was 30 wt%, the amount of N',N'-methylenebisacrylamide was 0.75 wt% of the total amount of hydrophilic and hydrophobic monomers, and the amount of α-ketoglutaric acid was 0.25 wt% of the total amount of hydrophilic and hydrophobic monomers. The molar ratio of hydrophilic to hydrophobic monomers was 1:2.

[0079] The prepared precursor solution A was injected into a mold consisting of two soda-lime glass slides (separated by a 2 mm thick hollow silicone gasket) to obtain sample B. Sample B was placed in an ultraviolet box and polymerized under 365 nm ultraviolet light for 4 h to obtain amphiphilic polyelectrolyte gel.

[0080] (2) Preparation of electrolyte solution: Add redox ion pair and LiCl to deionized water, stir to dissolve and prepare electrolyte aqueous solution, wherein the concentration of redox ion pair is 0.4M and the mass concentration of LiCl is 2.5wt% to obtain electrolyte solution; the redox ion pair is potassium ferricyanide and potassium ferrocyanide;

[0081] (3) Immerse the amphiphilic polyelectrolyte gel in an electrolyte solution for 48 hours to obtain the SPAK / PEA conventional hydrogel thermoelectric material.

[0082] The electrical properties and humidity stability of the obtained SPAK / PEA conventional hydrogel thermoelectric material were tested under a 10 °C temperature difference. The results are as follows: Figure 4 , Figure 8 , Figure 9 As shown. From Figure 4 , Figure 8 , Figure 9 It can be seen that its output power density can reach up to 2.07 mW / m³ at 30% humidity. 2 The Seebeck coefficient is 0.3 mV / K, and the internal moisture content is stable at 2.13 wt%; the maximum output power density can reach 18.48 mW / m³ at 99% humidity. 2 The Seebeck coefficient is 1.53 mV / K, and the internal water content remains stable at 60.16 wt%. It can be seen that under humidity variations of 30%-90%, the internal water content of the conventional SPAK / PEA hydrogel thermoelectric material changes from 2.13 wt% to 60.16 wt%, a much larger change than that of the thermoelectric material in Example 1.

[0083] Comparative Example 2

[0084] This comparative example demonstrates the preparation of a conventional hydrogel thermoelectric material using 2-acrylamido-2-methylpropanesulfonic acid and acrylamide as monomers. The specific steps are as follows:

[0085] (1) Preparation of polyelectrolyte gel: The negatively charged monomer 2-acrylamido-2-methylpropanesulfonic acid and the neutral monomer acrylamide, along with N',N'-methylenebisacrylamide crosslinking agent and α-ketoglutaric acid photoinitiator, were added to deionized water and magnetically stirred for 5 minutes. The mixture was then sonicated for 10 minutes to ensure complete dissolution of the monomers. Magnetic stirring was then continued for 5 minutes to obtain a homogeneous mixture. The mixture was allowed to stand at room temperature for 5 minutes to degas, yielding precursor solution A. The total amount of 2-acrylamido-2-methylpropanesulfonic acid and acrylamide in precursor solution A was 30 wt%, the amount of N',N'-methylenebisacrylamide added was 0.75 wt% of the total amount of 2-acrylamido-2-methylpropanesulfonic acid and acrylamide, and the amount of α-ketoglutaric acid added was 0.25 wt% of the total amount of 2-acrylamido-2-methylpropanesulfonic acid and acrylamide. The molar ratio of 2-acrylamido-2-methylpropanesulfonic acid to acrylamide was 1:3.

[0086] The prepared precursor solution A was injected into a mold consisting of two soda-lime glass slides (separated by a 2 mm thick hollow silicone gasket) to obtain sample B. Sample B was then placed in an ultraviolet chamber and polymerized under 365 nm ultraviolet light for 4 h to obtain a polyelectrolyte gel.

[0087] (2) Preparation of electrolyte solution: Dissolve redox ion pair and LiCl in deionized water by stirring to prepare an electrolyte aqueous solution, wherein the concentration of redox ion pair is 0.4 M and the mass concentration of LiCl is 2.5 wt%, and the electrolyte solution is obtained.

[0088] (3) The polyelectrolyte gel was immersed in an electrolyte solution for 48 hours to obtain the AMPS / AM conventional hydrogel thermoelectric material.

[0089] The electrical properties and humidity stability of the obtained AMPS / AM conventional hydrogel thermoelectric material were tested under a 10 °C temperature difference. The results are as follows: Figure 5 , Figure 8 and Figure 9 As shown. From Figure 5 , Figure 8 and Figure 9 It can be seen that its output power density can reach up to 0.24 mW / m at 30% humidity. 2 The Seebeck coefficient is 0.01 mV / K, and the internal water content is stable at 0.37 wt%; the maximum output power density can reach 12.58 mW / m³ at 90% humidity. 2 The Seebeck coefficient is 1.39 mV / K, and the internal water content remains stable at 83.77 wt%. It can be seen that under humidity variations of 30%-90%, the internal water content of the conventional AMPS / AM hydrogel thermoelectric material changes from 0.37 wt% to 83.77 wt%, a much larger change than that of the thermoelectric material in Example 2.

Claims

1. A method for preparing a quasi-solid thermoelectric material that achieves humidity stability through phase separation control, characterized in that, The specific steps include: (1) Dissolve negatively charged hydrophilic monomers, electrically neutral monomers, crosslinking agents and photoinitiators in a solvent to obtain precursor solution A, and then carry out ultraviolet light polymerization reaction to form polyelectrolyte gel; (2) A quaternary electrolyte system is obtained by mixing a eutectic solvent and an aqueous electrolyte containing redox ion pairs and lithium chloride. (3) The gel obtained in step (1) is immersed in the quaternary electrolyte system in step (2) and the internal solution is fully replaced by diffusion to obtain a quasi-solid thermoelectric material with stable humidity.

2. The method for preparing a quasi-solid-state thermoelectric material with humidity stability achieved by phase separation control according to claim 1, characterized in that, The negatively charged hydrophilic monomer is selected from monomers containing sulfonate ions; the electrically neutral monomer is acrylamide or an electrically neutral monomer containing a benzene ring hydrophobic group.

3. The method for preparing a quasi-solid-state thermoelectric material with humidity stability achieved by phase separation control according to claim 2, characterized in that, The negatively charged hydrophilic monomer is 2-acrylamido-2-methylpropanesulfonic acid or potassium 3-sulfopropylacrylate; the electrically neutral monomer containing a benzene ring hydrophobic group is 2-phenoxyethyl acrylate; the solvent is an organic solvent or deionized water.

4. The method for preparing a quasi-solid-state thermoelectric material with humidity stability achieved by phase separation control according to claim 1, characterized in that, The total concentration of negatively charged hydrophilic monomers and electrically neutral monomers in precursor solution A is 20-50 wt%, and the molar ratio of negatively charged hydrophilic monomers to electrically neutral monomers is 3:1 to 1:3; the amount of photoinitiator added is 0.1-0.5 wt% of the total amount of negatively charged hydrophilic monomers and electrically neutral monomers, and the amount of crosslinking agent added is 0.5-1 wt% of the total amount of negatively charged hydrophilic monomers and electrically neutral monomers; the crosslinking agent is N',N'-methylenebisacrylamide; the photoinitiator is α-ketoglutaric acid.

5. The method for preparing a quasi-solid-state thermoelectric material with humidity stability achieved by phase separation control according to claim 1, characterized in that, In step (1), the ultraviolet light wavelength is 365nm; the polymerization time is 2~6h.

6. The method for preparing a quasi-solid-state thermoelectric material with humidity stability achieved by phase separation control according to claim 1, characterized in that, In step (2), the eutectic solvent is a mixture of choline chloride and glycerol, with a molar ratio of choline chloride to glycerol of 1:1 to 1:

3.

7. The method for preparing a quasi-solid-state thermoelectric material with humidity stability achieved by phase separation control according to claim 1, characterized in that, In step (2), the concentration of redox ion pairs in the electrolyte aqueous solution is 0.2M~0.4M, and the mass concentration of LiCl is 10wt%~30wt%; the redox ion pairs are potassium ferricyanide and potassium ferrocyanide.

8. The method for preparing a quasi-solid-state thermoelectric material with humidity stability achieved by phase separation control according to claim 1, characterized in that, In step (2), the content of the eutectic solvent in the quaternary electrolyte system is 50~95wt%, and the content of the electrolyte aqueous solution is 5~50wt%; in step (3), the replacement treatment time is 48 hours.

9. A quasi-solid thermoelectric material that achieves humidity stability by phase separation, prepared by the preparation method according to any one of claims 1-8.

10. The application of the quasi-solid thermoelectric material with humidity stability achieved by phase separation as described in claim 9 in wearable materials.

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