A Ti3C2T x Method of application of hydrogels in ionic thermoelectric devices

Abstract

A Ti3C2T x The application method of hydrogel in ionic thermoelectric devices belongs to the technical field of thermoelectric materials. The prepared dispersion liquid is mixed with a gel solution, defoamed by ultrasonic, and then frozen to form physical crosslinking, thereby preparing Ti3C2T x Hydrogel, then according to the needs of the frozen state of hydrogel thawing, cutting, the obtained slice is soaked in a mixed solution of a redox couple and a water-soluble metal salt, and then the current collector is connected with the tab, and finally the ionic thermoelectric device is obtained. The application introduces Ti3C2T x , which enhances the difference in ion migration rate inside the gel, so that the thermoelectric performance can be affected by changing the type of water-soluble metal salt; the introduction of redox couple reaction promotes charge separation and drives current generation; and the thermoelectric potential generated by ionic thermal diffusion effect and the thermoelectric potential generated by redox reaction are superimposed, which further improves the overall thermoelectric performance.

Description

Technical Field

[0001] This invention belongs to the field of thermoelectric materials technology, and relates to a Ti3C2T x Application methods of hydrogels in ion thermoelectric devices. Background Technology

[0002] In modern society, energy is of paramount importance, especially sustainable and clean energy sources. Thermoelectric (TE) effect, a phenomenon that converts heat energy into electrical energy, provides a practical solution for utilizing low-grade heat energy. For decades, researchers have conducted extensive and in-depth research on thermoelectric materials. Traditional electronic thermoelectric materials (e-TEs) have seen rapid development in applications such as thermoelectric generators and thermal sensors, and have been implemented to varying degrees. However, most e-TEs materials are based on semiconductors or metal alloys (such as Bi₂Te₃), but the combination of rare elements is not only environmentally unfriendly but also scarce and expensive, with material costs accounting for more than half of the manufacturing cost of thermoelectric power generation modules. Furthermore, from a performance perspective, the thermoelectric performance of e-TEs materials is low at room temperature and is approaching its theoretical limit. This makes it difficult to scale up thermoelectric power generation for practical applications.

[0003] In recent years, the development of nanotechnology has brought a completely new research perspective to this field. Compared with e-TE systems, ion thermoelectric (i-TE) systems stand out due to their Seebeck coefficient being several orders of magnitude higher. The thermoelectric effect in ion systems originates from the Soret effect, where ions migrate from the hot end to the cold end through thermophoresis. An increase in the ion concentration at the cold end causes ions to diffuse back towards the hot end due to the concentration gradient. Since the ions carry a charge, the electric field interacts with the thermophoretic effect. Ultimately, under the combined action of these three thermodynamic forces, the system reaches an equilibrium state.

[0004] i-TEs materials have advantages such as environmental friendliness, low cost, and good performance. However, compared with electronic thermoelectric materials, ion thermoelectric systems still face a key challenge: the generation of their thermoelectric potential is affected by the difference in diffusion rates between anions and cations. How to increase the difference in diffusion rates between anions and cations within the same thermoelectric material is the key to achieving high-performance ion thermoelectricity. When there is a temperature difference between the two ends of the thermoelectric material, anions and cations diffuse towards the cold end or the hot end under thermal drive. If the difference in migration rates between the two is too small, an effective electrochemical potential difference cannot be established. Only when a certain ion has a significantly higher migration rate can an observable macroscopic thermoelectric potential be formed within the material, thereby realizing electrical energy output. Summary of the Invention

[0005] To address the shortcomings of the prior art described in the background section, this invention provides a Ti3C2T xHydrogels and methods for preparing ion thermoelectric devices to achieve controllable adjustment of ion thermoelectric performance.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] This invention provides a Ti3C2T x The application method of hydrogels in ion thermoelectric devices includes the following steps:

[0008] Ti3C2T was obtained by etching the MAX precursor and centrifuging. x Dispersion; the gel matrix powder was dissolved in deionized water and heated in a water bath to prepare a gel solution; the gel solution was subjected to ultrasonic defoaming treatment and then reacted with Ti3C2T x The dispersions are mixed and stirred until homogeneous, then placed in a vacuum environment for ultrasonic defoaming again; the resulting mixture is then poured into a mold and frozen to form physical cross-linking.

[0009] After thawing the frozen hydrogel at room temperature, Ti3C2T x The hydrogel was cut, and the resulting slices were immersed in a mixed solution of a redox couple and a water-soluble metal salt. Two current collectors were then attached to the immersed Ti3C2T. x The hydrogel is then applied to both sides; subsequently, the two tabs are connected to the current collector to obtain the ion thermoelectric device. Finally, the entire ion thermoelectric device is encapsulated to prevent moisture evaporation during the testing process.

[0010] The above application method, wherein:

[0011] In some embodiments of the present invention, the MAX precursor is either aluminum titanium carbide or silicon titanium carbide;

[0012] In some embodiments of the present invention, the Ti3C2T x The concentration of the dispersion is 5 mg / mL-15 mg / mL.

[0013] In some embodiments of the present invention, the gel matrix is ​​one or more of polyvinyl alcohol (PVA), gelatin, sodium alginate, and chitosan;

[0014] In some embodiments of the present invention, the redox couple is K3Fe(CN)6 / K4Fe(CN)6;

[0015] In some embodiments of the present invention, the water-soluble metal salt is one or more of alkali metal halides; more preferably, the water-soluble metal salt is one of KCl, NaCl, and LiCl.

[0016] In some embodiments of the present invention, the mass fraction of the gel in the solution is 5% to 15%, preferably 15%;

[0017] In some embodiments of the present invention, the concentration of the water-soluble metal salt is 0.1 mol / L to 2 mol / L;

[0018] In some embodiments of the present invention, the water bath heating temperature is 65°C to 95°C, preferably 90°C;

[0019] In some embodiments of the present invention, the two ultrasonic defoaming processes have the same power, which is 200W~300W;

[0020] In some embodiments of the present invention, the current collector is graphite foil, nickel foil, or nickel foam;

[0021] In some embodiments of the present invention, the electrode tab is a nickel electrode tab;

[0022] In some embodiments of the present invention, the ion thermogel device is encapsulated with an aluminum-plastic film or a polyethylene film.

[0023] The key points of this invention are:

[0024] 1. This invention utilizes Ti3C2T x The introduction of [a specific substance] enhances the difference in ion migration rates within the gel, thereby affecting thermoelectric properties by altering the type of water-soluble metal salt.

[0025] 2.Ti3C2T x Preparation methods of hydrogels and ion thermoelectric devices.

[0026] This invention introduces Ti3C2T into the gel matrix x This enhances the difference in ion migration rates within the gel. Under the influence of the temperature gradient, cations and anions migrate towards the cold end, generating thermoelectric potential through ion thermal diffusion. Specifically, Ti3C2T... x The synergistic effect process is as follows: the electrolyte in the gel dissociates into cations and anions, which migrate simultaneously from the hot end to the cold end under temperature gradient conditions. Based on Ti3C2T x The potential surface modulating effect and the abundant negatively charged groups on its surface establish an asymmetric ion transport barrier within the gel matrix. The diffusion coefficients of anions and cations in the gel differ significantly, and this difference promotes charge separation, thereby generating a higher thermoelectric potential. Meanwhile, Fe(CN)6 4- / Fe(CN)6 3-Redox couples promote charge separation through redox reactions, and the resulting electrons migrate from a high-temperature region to a low-temperature region via an external circuit, driving current generation. During this process, the increased charge gradient strengthens the driving force of the redox reaction, facilitating a more efficient electron transfer process. Furthermore, the thermoelectric potential generated by the ion thermal diffusion effect and the thermoelectric potential generated by the redox reaction are superimposed, further enhancing the overall thermoelectric performance. Based on these principles, the Ti3C2T prepared in this invention... x Hydrogels have a high Seebeck coefficient. Attached Figure Description

[0027] Figure 1 The Ti3C2T of Embodiment 1 of the present invention x Schematic diagram of hydrogel; where (a) is Ti3C2T x (b) is the thawed Ti3C2T gel solution. x Gel sheets;

[0028] Figure 2 The Ti3C2T of Embodiment 1 of the present invention x Structural characterization diagrams of hydrogels; where (a) is the infrared spectrum, (b) is the X-ray diffraction spectrum, and (c) is the photoelectron spectrum;

[0029] Figure 3 This is a migration path diagram of different ions calculated in this invention; where (a) is Li + , (b) is Na + (c) is K + (d) is Cl - ;

[0030] Figure 4 The ions of this invention and Cl - Ion migration barrier difference diagram;

[0031] Figure 5 The graphs show the linear relationship between voltage and temperature of the ion thermoelectric devices obtained in different embodiments and comparative examples, and their Seebeck coefficients; where (a) is the linear relationship between voltage and temperature, and (b) is the Seebeck coefficient. Detailed Implementation

[0032] This invention provides a Ti3C2T x The application method of hydrogels in ion thermoelectric devices includes the following steps:

[0033] Hydrogel preparation: Using aluminum titanium carbide or silicon titanium carbide as MAX precursors, the precursors were etched and then centrifuged to obtain Ti3C2T with concentrations of 5 mg / mL-20 mg / mL. xDispersion. The gel matrix powder was dissolved in deionized water and heated in a water bath at 65℃~95℃ to obtain a gel solution with a mass concentration of 5%-15%. The gel solution was then subjected to ultrasonic defoaming treatment at a power of 300W and then reacted with Ti3C2T. x The dispersion was mixed and stirred until homogeneous, then placed in a vacuum environment for further defoaming to obtain a final mixture. This mixture was then poured into a mold and frozen to form physical cross-links, yielding frozen Ti3C2T. x spare.

[0034] Fabrication of ion thermoelectric devices: Ion thermoelectric devices made from frozen Ti3C2T x The hydrogel was cut to specific dimensions to obtain Ti3C2T x Hydrogel slices were immersed in a mixed solution containing a K3Fe(CN)6 / K4Fe(CN)6 redox couple and 0.1 mol / L to 2 mol / L water-soluble metal salts. Two current collectors, using graphite foil, nickel foil, or nickel foam as current collectors, were attached to the immersed Ti3C2T hydrogel. x The hydrogel is sliced ​​on both sides, and then two nickel tabs or copper-plated nickel tabs are connected to the current collector as electrodes. The entire system is then encapsulated with an aluminum-plastic film or a polyethylene film to obtain the ion thermoelectric device.

[0035] The gel matrix in this invention is one or more of polyvinyl alcohol, gelatin, sodium alginate, and chitosan.

[0036] The water-soluble metal salt in this invention is one or more of alkali metal halides and transition metal halides; more preferably, the water-soluble metal salt is one or more of KCl, NaCl, and LiCl.

[0037] The following specific embodiments further illustrate the content of the present invention in detail. Unless otherwise specified, the raw materials used in the following embodiments were obtained through conventional commercial methods or simple synthesis. The Ti3C2T used in the following embodiments... x The dispersions were all obtained through conventional processes.

[0038] Example 1:

[0039] This embodiment provides a Ti3C2T x The application method of hydrogels in ion thermoelectric devices includes the following steps:

[0040] Hydrogel preparation: Using titanium aluminum carbide as the MAX precursor, it was etched and centrifuged to obtain Ti3C2T with a concentration of 15 mg / mL. xDispersion. Polyvinyl alcohol (PVA) powder was dissolved in deionized water and heated in a water bath at 90°C for 2 hours to prepare a PVA solution with a PVA mass fraction of 15%. The PVA solution was then subjected to ultrasonic defoaming at 300W. 10 mL of the PVA solution was then mixed with 600 μL of Ti3C2T... x The dispersion was mixed. After stirring until homogeneous, it was ultrasonically defoamed in a vacuum environment at the same power for 1 hour to obtain a hydrogel mixture (e.g., Figure 1 (a) The resulting mixture was poured into a rectangular mold and frozen at -25°C for 12 hours to allow physical cross-linking between the PVA chains, resulting in frozen Ti3C2T. x spare.

[0041] Fabrication of ion thermoelectric devices: Before fabricating the devices, Ti3C2T in a frozen state was... x The hydrogel was cut to a specific size and then thawed at room temperature for 3 hours to obtain PVA-Ti3C2T. x Hydrogels (such as) Figure 1 (b) As shown in the figure. Take a piece of PVA-Ti3C2T x The hydrogel was cut into square pieces measuring 4cm × 4cm × 0.3cm, and the pieces were then immersed in a solution containing 0.1mol / L Fe(CN)6. 4- 0.1 mol / L Fe(CN)6 3- The sample was immersed in a mixed solution of 2 mol / L KCl for 12 hours. Two pieces of nickel foam were attached to both sides of the immersed square plate, with each side having a contact area of ​​4 cm × 4 cm with the nickel foam electrode. Subsequently, the two nickel tabs were connected to the nickel foam using nickel-plated rivets, serving as electrodes. Finally, the entire device was encapsulated in an aluminum-plastic film to prevent moisture evaporation during the test.

[0042] The PVA-Ti3C2T prepared in this embodiment x The structural characterization results of the thermoelectric gel are as follows Figure 2 As shown. Figure 2 As shown in (a), the thermoelectric gel prepared according to this embodiment exhibits two characteristic peaks (3277 cm⁻¹) in the high wavenumber region, as can be seen from the infrared spectrum. -1 and 2914cm -1 These correspond to O-H stretching vibration and C-H stretching vibration, respectively. 1634 cm -1 The absorption peak at 1416 cm⁻¹ is attributed to the C═O stretching vibration, while the remaining characteristic peaks correspond to the following CO bond-related stretching vibrations: OH─C─OH (1416 cm⁻¹). -1 ), C─O─C (1326cm) -1 ) and C─O─C─OH (1088cm -1 This signifies that PVA-Ti3C2T xThe successful cross-linking. Figure 2 The XRD patterns of Ti3C2T located near 7.9° in (b) and (c) x The 002 characteristic peak and the Ti 2p characteristic peak in the XPS plot indicate the successful doping of MXene in the PVA gel. Figure 3 and 4 As shown, the LST / QST method was used to calculate the quantum mechanical computation of different ions in Ti3C2T using the CASTEP quantum mechanical computation tool. x The difference in the migration barrier on the surface, K in this embodiment + The migration barrier of the ion is 0.008 eV, compared to Cl. - The difference in the migration energy barrier of the ions is 0.248 eV. Figure 5 (a) indicates that the open-circuit voltage of the thermoelectric gel prepared according to this embodiment corresponds to the temperature difference, and the open-circuit voltage is 120.8mV at a temperature difference of 40°C. Figure 5 (b) The slope of the linear fit between the open-circuit voltage and the temperature difference is the corresponding Seebeck coefficient, which has a value of 2.8 mV·K. -1 .

[0043] Example 2:

[0044] This embodiment provides a Ti3C2T x The application method of hydrogels in ion thermoelectric devices includes the following steps:

[0045] Hydrogel preparation: Using titanium aluminum carbide as the MAX precursor, it was etched and centrifuged to obtain Ti3C2T with a concentration of 15 mg / mL. x Dispersion. Polyvinyl alcohol (PVA) powder was dissolved in deionized water and heated in a water bath at 90°C for 2 hours to prepare a PVA solution with a PVA mass fraction of 15%. After ultrasonic defoaming treatment of the PVA solution at 300W, 10 mL of the PVA solution was mixed with 600 μL of Ti3C2T... x The dispersions were mixed. After thorough stirring, the mixture was ultrasonically defoamed in a vacuum environment with the same power for 1 hour. The resulting mixture was poured into a cuboid mold and frozen at -25°C for 12 hours to allow physical cross-linking between the PVA chains, yielding frozen Ti3C2T. x spare.

[0046] Fabrication of ion thermoelectric devices: Before fabricating the devices, Ti3C2T in a frozen state was... x The hydrogel was cut to a specific size and then thawed at room temperature for 3 hours to obtain PVA-Ti3C2T. x Hydrogel. Take a piece of PVA-Ti3C2T xThe hydrogel was cut into square pieces measuring 4cm × 4cm × 0.3cm, and the pieces were then immersed in a solution containing 0.1mol / L Fe(CN)6. 4- 0.1 mol / L Fe(CN)6 3- The sample was immersed in a mixed solution of 2 mol / L NaCl for 12 hours. Two pieces of nickel foam were attached to both sides of the immersed square plate, with each side having a contact area of ​​4 cm × 4 cm with the nickel foam electrode. Subsequently, the two nickel tabs were connected to the nickel foam using nickel-plated rivets, serving as electrodes. Finally, the entire device was encapsulated in an aluminum-plastic film to prevent moisture evaporation during the test.

[0047] like Figure 3 and 4 As shown, the LST / QST method was used to calculate the quantum mechanical computation of different ions in Ti3C2T using the CASTEP quantum mechanical computation tool. x The difference in migration barriers on the surface, in this embodiment Na + The migration barrier of the ion is 0.03 eV, compared to Cl. - The difference in the migration energy barrier of the ions is 0.226 eV. Figure 5 (a) indicates that the open-circuit voltage of the thermoelectric gel prepared according to this embodiment corresponds to the temperature difference, and the open-circuit voltage is 75.1mV at a temperature difference of 40°C. Figure 5 (b) The slope of the linear fit between the open-circuit voltage and the temperature difference is the corresponding Seebeck coefficient, which has a value of 1.7 mV·K. -1 .

[0048] Example 3:

[0049] This embodiment provides a Ti3C2T x The application method of hydrogels in ion thermoelectric devices includes the following steps:

[0050] Hydrogel preparation: Using titanium aluminum carbide as the MAX precursor, it was etched and centrifuged to obtain Ti3C2T with a concentration of 15 mg / mL. x Dispersion. Polyvinyl alcohol (PVA) powder was dissolved in deionized water and heated in a water bath at 90°C for 2 hours to prepare a PVA solution with a PVA mass fraction of 15%. After ultrasonic defoaming treatment of the PVA solution at 300W, 10 mL of the PVA solution was mixed with 600 μL of Ti3C2T... x The dispersions were mixed. After thorough stirring, the mixture was ultrasonically defoamed in a vacuum environment with the same power for 1 hour. The resulting mixture was poured into a cuboid mold and frozen at -25°C for 12 hours to allow physical cross-linking between the PVA chains, yielding frozen Ti3C2T. x spare.

[0051] Fabrication of ion thermoelectric devices: Before fabricating the devices, Ti3C2T in a frozen state was... x The hydrogel was cut to a specific size and then thawed at room temperature for 3 hours to obtain PVA-Ti3C2T. x Hydrogel. Take a piece of PVA-Ti3C2T x The hydrogel was cut into square pieces measuring 4cm × 4cm × 0.3cm, and the pieces were then immersed in a solution containing 0.1mol / L Fe(CN)6. 4- 0.1 mol / L Fe(CN)6 3- The sample was immersed in a mixed solution of 2 mol / L LiCl for 12 hours. Two pieces of nickel foam were attached to both sides of the immersed square plate, with each side having a contact area of ​​4 cm × 4 cm with the nickel foam electrode. Subsequently, the two nickel tabs were connected to the nickel foam using nickel-plated rivets, serving as electrodes. Finally, the entire device was encapsulated in an aluminum-plastic film to prevent moisture evaporation during the test.

[0052] like Figure 3 and 4 As shown, the LST / QST method was used to calculate the quantum mechanical computation of different ions in Ti3C2T using the CASTEP quantum mechanical computation tool. x The difference in migration barriers on the surface, in this embodiment Li + The migration barrier of the ion is 0.078 eV, compared to Cl. - The difference in the migration energy barrier of the ions is 0.178 eV. Figure 5 (a) indicates that the open-circuit voltage of the thermoelectric gel prepared according to this embodiment corresponds to the temperature difference, and the open-circuit voltage is 38.8mV at a temperature difference of 40°C. Figure 5 (b) The slope of the linear fit between the open-circuit voltage and the temperature difference is the corresponding Seebeck coefficient, with a value of 0.83 mV·K. -1 .

[0053] Comparative Example 1:

[0054] This comparative example provides a Ti3C2T x The application method of hydrogels in ion thermoelectric devices includes the following steps:

[0055] Hydrogel preparation: Using titanium aluminum carbide as the MAX precursor, it was etched and centrifuged to obtain Ti3C2T with a concentration of 15 mg / mL. x Dispersion. Polyvinyl alcohol (PVA) powder was dissolved in deionized water and heated in a water bath at 90°C for 2 hours to prepare a PVA solution with a PVA mass fraction of 15%. After ultrasonic defoaming treatment of the PVA solution at 300W, 10 mL of the PVA solution was mixed with 600 μL of Ti3C2T... xThe dispersion was mixed. After stirring until homogeneous, the mixture was ultrasonically defoamed at the same power for 1 hour in a vacuum environment. The resulting mixture was poured into a cuboid mold and frozen at -25°C for 12 hours to allow physical cross-linking between the PVA chains, yielding frozen Ti3C2T. x spare.

[0056] Fabrication of ion thermoelectric devices: Before fabricating the devices, Ti3C2T in a frozen state was... x The hydrogel was cut to a specific size and then thawed at room temperature for 3 hours to obtain PVA-Ti3C2T. x Hydrogel. Take a piece of PVA-Ti3C2T x The hydrogel was cut into square pieces measuring 4cm × 4cm × 0.3cm, and the pieces were then immersed in a solution containing 0.1mol / L Fe(CN)6. 4- 0.1 mol / L Fe(CN)6 3- The sample was immersed in a mixed solution of 1 mol / L FeCl2 for 12 hours. Two pieces of nickel foam were attached to both sides of the immersed square plate, with each side having a contact area of ​​4 cm × 4 cm with the nickel foam electrode. Subsequently, the two nickel tabs were connected to the nickel foam using nickel-plated rivets to serve as electrodes. Finally, the entire device was encapsulated in an aluminum-plastic film to prevent moisture evaporation during the test.

[0057] Figure 5 (a) indicates that the open-circuit voltage of the thermoelectric gel prepared according to this embodiment corresponds to the temperature difference, and the open-circuit voltage is 26.9mV at a temperature difference of 40°C. Figure 5 (b) The slope of the linear fit between the open-circuit voltage and the temperature difference is the corresponding Seebeck coefficient, which has a value of 0.66 mV·K. -1 .

[0058] Comparative Example 2:

[0059] This comparative example provides a method for applying hydrogel in ion thermoelectric devices, including the following steps:

[0060] Hydrogel preparation: Polyvinyl alcohol (PVA) powder was dissolved in deionized water and heated in a water bath at 90°C for 2 hours to prepare a PVA solution with a PVA mass fraction of 15%. The PVA solution was defoamed in a vacuum environment at 200W, then poured into a cuboid mold and frozen at -25°C for 12 hours to allow physical cross-linking between the PVA chains, resulting in a frozen hydrogel for later use.

[0061] Thermoelectric device fabrication: Before fabricating the device, the frozen hydrogel was cut to specific dimensions and thawed at room temperature for 3 hours to obtain PVA hydrogel. A piece of PVA hydrogel was taken and cut into square pieces measuring 4cm × 4cm × 0.3cm. The square pieces were then immersed in a solution containing 0.1mol / L Fe(CN)6. 4- 0.1 mol / L Fe(CN)6 3- The sample was immersed in a mixed solution of 1 mol / L FeCl2 for 12 hours. Two pieces of nickel foam were attached to both sides of the immersed square plate, with each side having a contact area of ​​4 cm × 4 cm with the nickel foam electrode. Subsequently, the two nickel tabs were connected to the nickel foam using nickel-plated rivets to serve as electrodes. Finally, the entire device was encapsulated in an aluminum-plastic film to prevent moisture evaporation during the test.

[0062] Figure 5 (a) indicates that the open-circuit voltage of the thermoelectric gel prepared according to this embodiment corresponds to the temperature difference, and the open-circuit voltage is 6mV at a temperature difference of 40°C. Figure 5 (b) The slope of the linear fit between the open-circuit voltage and the temperature difference is the corresponding Seebeck coefficient, with a value of 0.09 mV·K. -1 .

[0063] Example 4:

[0064] This embodiment provides a Ti3C2T x The application method of hydrogels in ion thermoelectric devices includes the following steps:

[0065] Hydrogel preparation: Using silicon carbide titanium as the MAX precursor, it was etched and centrifuged to obtain Ti3C2T with a concentration of 15 mg / mL. x Dispersion. Polyvinyl alcohol (PVA) powder was dissolved in deionized water and heated in a water bath at 65°C for 2 hours to prepare a PVA solution with a PVA mass fraction of 5%. The PVA solution was then subjected to ultrasonic defoaming at 300W. 10 mL of the PVA solution was then mixed with 600 μL of Ti3C2T... x The dispersion was mixed. After thorough stirring, it was ultrasonically defoamed in a vacuum environment at the same power for 1 hour. The resulting mixture was poured into a cuboid mold and frozen at -25°C for 12 hours to allow physical cross-linking between the PVA chains, yielding frozen Ti3C2T. x spare.

[0066] Fabrication of ion thermoelectric devices: Before fabricating the devices, Ti3C2T in a frozen state was... x The hydrogel was cut to a specific size and then thawed at room temperature for 3 hours to obtain PVA-Ti3C2T. x Hydrogel. One sheet of PVA-Ti3C2T xThe hydrogel was cut into square pieces measuring 4cm × 4cm × 0.3cm, and the pieces were then immersed in a solution containing 0.1mol / L Fe(CN)6. 4- 0.1 mol / L Fe(CN)6 3- The sample was immersed in a mixed solution of 2 mol / L KCl for 12 hours. Two graphite foils were attached to both sides of the immersed square sheet, with each side having a contact area of ​​4 cm × 4 cm with the graphite foil electrode. Subsequently, two nickel tabs were connected to the graphite foils with nickel-plated rivets to serve as electrodes. Finally, the entire device was sealed in a polyethylene film to prevent moisture evaporation during the test.

[0067] In this embodiment, K + The migration barrier of the ion is 0.008 eV, compared to Cl. - The difference in the migration energy barrier of the ions is 0.248 eV. Figure 5 This indicates that the open-circuit voltage of the thermoelectric gel prepared according to this embodiment corresponds to the temperature difference, with an open-circuit voltage of 110.2 mV at a temperature difference of 40°C. The Seebeck coefficient is 2.5 mV·K. -1 .

[0068] Example 5:

[0069] This embodiment provides a Ti3C2T x The application method of hydrogels in ion thermoelectric devices includes the following steps:

[0070] Hydrogel preparation: Using silicon carbide titanium as the MAX precursor, it was etched and centrifuged to obtain Ti3C2T with a concentration of 15 mg / mL. x Dispersion. Polyvinyl alcohol (PVA) powder was dissolved in deionized water and heated in a water bath at 90°C for 2 hours to prepare a PVA solution with a PVA mass fraction of 15%. The PVA solution was then subjected to ultrasonic defoaming at 300W. 10 mL of the PVA solution was then mixed with 600 μL of Ti3C2T... x The dispersion was mixed. After thorough stirring, it was ultrasonically defoamed in a vacuum environment at the same power for 1 hour. The resulting mixture was poured into a cuboid mold and frozen at -25°C for 12 hours to allow physical cross-linking between the PVA chains, yielding frozen Ti3C2T. x spare.

[0071] Fabrication of ion thermoelectric devices: Before fabricating the devices, Ti3C2T in a frozen state was... x The hydrogel was cut to a specific size and then thawed at room temperature for 3 hours to obtain PVA-Ti3C2T. x Hydrogel. Take a piece of PVA-Ti3C2T xThe hydrogel was cut into square pieces measuring 4cm × 4cm × 0.3cm, and the pieces were then immersed in a solution containing 0.1mol / L Fe(CN)6. 4- 0.1 mol / L Fe(CN)6 3- The sample was immersed in a mixed solution of 2 mol / L KCl for 12 hours. Two graphite foils were attached to both sides of the immersed square sheet, with each side having a contact area of ​​4 cm × 4 cm with the graphite foil electrode. Subsequently, two nickel tabs were connected to the graphite foils with nickel-plated rivets to serve as electrodes. Finally, the entire device was sealed in a polyethylene film to prevent moisture evaporation during the test.

[0072] In this embodiment, K + The migration barrier of the ion is 0.008 eV, compared to Cl. - The difference in the migration energy barrier of the ions is 0.248 eV. Figure 5 This indicates that the open-circuit voltage of the thermoelectric gel prepared according to this embodiment corresponds to the temperature difference, with an open-circuit voltage of 69.3 mV at a temperature difference of 40°C. The Seebeck coefficient is 1.8 mV·K. -1 .

[0073] The open-circuit voltage of the ion thermoelectric gel capacitors prepared according to Examples 1-5 was between 38.8mV and 120.8mV under a temperature difference of 40°C, and the Seebeck coefficient was between 0.83mV / K and 2.8mV / K, which is consistent with the calculated results.

Claims

1. A Ti3C2T x The method for applying hydrogels in ion thermoelectric devices is characterized by, Includes the following steps: Hydrogel preparation: Ti3C2T was obtained by etching the MAX precursor and centrifuging. x Dispersion; the gel matrix powder was dissolved in deionized water and heated in a water bath to prepare a gel solution; the gel solution was subjected to ultrasonic defoaming treatment and then reacted with Ti3C2T x After the dispersion is mixed and stirred evenly, it is placed in a vacuum environment for ultrasonic defoaming again; then the resulting mixture is poured into a mold and frozen to form physical cross-linking, thus obtaining frozen Ti3C2T. x Hydrogel for later use; Fabrication of ion thermoelectric devices: After thawing the frozen hydrogel at room temperature, Ti3C2T... x The hydrogel was cut, and the resulting slices were immersed in a mixed solution of a redox couple and a water-soluble metal salt. Two current collectors were then attached to the immersed Ti3C2T. x The two sides of the hydrogel were then connected; subsequently, the two tabs were connected to the current collector to obtain an ion thermoelectric device.

2. A Ti3C2T according to claim 1 x The method for applying hydrogels in ion thermoelectric devices is characterized by, The MAX precursor is aluminum titanium carbide or silicon titanium carbide; the gel matrix is ​​one or more of polyvinyl alcohol, gelatin, sodium alginate, and chitosan.

3. A Ti3C2T according to claim 1 x The method for applying hydrogels in ion thermoelectric devices is characterized by, Ti3C2T x The concentration of the dispersion is 5 mg / mL-15 mg / mL.

4. A Ti3C2T according to claim 1 x The method for applying hydrogels in ion thermoelectric devices is characterized by, The water bath heating temperature is 65℃~95℃.

5. A Ti3C2T according to claim 1 x The method for applying hydrogels in ion thermoelectric devices is characterized by, The ultrasonic defoaming power was the same in both cases, ranging from 200W to 300W.

6. A Ti3C2T according to claim 1 x The method for applying hydrogels in ion thermoelectric devices is characterized by, The gel is in a gel solution, and the mass fraction of the gel is 5% to 15%.

7. A Ti3C2T according to claim 1 x The method for applying hydrogels in ion thermoelectric devices is characterized by, The redox couple is K3Fe(CN)6 / K4Fe(CN)6; Water-soluble metal salts are one or more alkali metal halides.

8. A Ti3C2T according to claim 7 x The method for applying hydrogels in ion thermoelectric devices is characterized by, The water-soluble metal salt is one of KCl, NaCl, and LiCl.

9. A Ti3C2T according to claim 1 x The method for applying hydrogels in ion thermoelectric devices is characterized by, The current collector is graphite foil, nickel foil, or nickel foam; the tab is a nickel-based tab.

10. A Ti3C2T according to claim 1 x The method for applying hydrogels in ion thermoelectric devices is characterized by, The method also includes encapsulating the obtained ion thermoelectric device with an aluminum-plastic film or a polyethylene film.

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