Ionic thermoelectric gel material, preparation method and application thereof

Abstract

The application discloses an ionic thermoelectric gel material and a preparation method and application thereof. Components of the ionic thermoelectric gel material include a hydrophilic polymer, a bio-based polymer, an electronic thermoelectric material, a water-soluble electrolyte and water. The preparation method comprises the following steps: dissolving the bio-based polymer in water, adding a hydrophilic monomer containing a carbon-carbon double bond, the electronic thermoelectric material, the water-soluble electrolyte, an initiator and a crosslinking agent, mixing uniformly, and then performing a free radical polymerization reaction through a method of ultraviolet light initiation or thermal initiation. The ionic thermoelectric gel material has the advantages of excellent thermoelectric conversion performance, excellent flame retardant performance, good flexibility and the like, can directly and sustainably supply power to external circuit electronic elements, and is suitable for use in the fields of intelligent fire fighting, energy storage devices, low-grade waste heat collection and conversion and the like.

Description

TECHNICAL FIELD

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

[0002] Thermoelectric conversion materials can realize the conversion of heat energy to electric energy through the migration of carriers (such as electrons, holes, ions, etc.) inside the material, and have a very broad application prospect in intelligent fire fighting, energy storage devices, energy enrichment and conversion, etc. Thermoelectric conversion materials can be divided into electronic thermoelectric materials (electrons / holes as carriers) and ionic thermoelectric materials (anions / cations as carriers) according to the types of migrating carriers. Although the existing electronic thermoelectric materials have excellent electrical conductivity, their Seebeck coefficients are generally only several tens to several hundred μV·K -1 (the thermoelectric potential generated by individual is generally lower than 200 μV·K -1 ), so it is usually necessary to collect hundreds or thousands of thermoelectric material components to realize normal power supply, which greatly increases the complexity and integration of the fire alarm response path. Although the existing ionic thermoelectric materials can generate a thermoelectric potential as high as mV·K -1 , the thermoelectric potential formed by ions under a temperature gradient can only be applied through an intermittent sensing capacitor, and cannot directly power electronic components. In summary, the existing electronic thermoelectric materials and ionic thermoelectric materials are difficult to fully meet the requirements of practical applications, and their applications are greatly limited.

[0003] Therefore, it is of great significance to develop a thermoelectric conversion material that can provide sustainable power supply, has high thermoelectric efficiency and excellent flame retardant performance. SUMMARY

[0004] The purpose of the present application is to provide an ionic thermoelectric gel material and a preparation method and application thereof.

[0005] The technical scheme adopted by the present application is as follows:

[0006] An ionic thermoelectric gel material, comprising the following components by mass percentage:

[0007] Hydrophilic polymer: 6.6% to 16.1%;

[0008] Biobased polymer: 1.2% to 6.7%;

[0009] Electronic thermoelectric material: 0.05% to 0.18%;

[0010] Water-soluble electrolyte: 3.0% to 3.3%;

[0011] Water: 74.6% to 87.5%.

[0012] Preferably, the hydrophilic polymer is polymerized from a hydrophilic monomer containing carbon-carbon double bond.

[0013] Preferably, the hydrophilic monomer containing carbon-carbon double bond is at least one of acrylamide, acrylic acid, 2-acrylamido-2-methylpropane sulfonic acid.

[0014] Preferably, the bio-based polymer is at least one of sodium alginate, carboxymethyl chitosan, sodium carboxymethyl cellulose.

[0015] Preferably, the electronic thermoelectric material is at least one of poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid, polypyrrole, polyaniline.

[0016] Preferably, the water-soluble electrolyte is at least one of sodium chloride, potassium chloride, sodium sulfate, potassium sulfate.

[0017] A method for preparing the ionic thermoelectric gel material as described above comprises the following steps: dissolving a bio-based polymer in water, then adding a hydrophilic monomer containing carbon-carbon double bond, an electronic thermoelectric material, a water-soluble electrolyte, an initiator and a crosslinking agent and mixing uniformly, and then performing a free radical polymerization reaction by ultraviolet light initiation or thermal initiation to obtain the ionic thermoelectric gel material.

[0018] Preferably, the dissolving method is magnetic stirring at room temperature, the stirring rate is 500 rpm to 800 rpm, and the stirring time is 14 h to 24 h.

[0019] Preferably, the initiator is at least one of ammonium persulfate, 2-hydroxy-2-methylpropiophenone.

[0020] Preferably, the amount of the initiator is 2.0% to 5.0% of the weight of the hydrophilic monomer containing carbon-carbon double bond.

[0021] Preferably, the crosslinking agent is at least one of N,N'-methylenebisacrylamide, ethylene glycol dimethacrylate.

[0022] Preferably, the amount of the crosslinking agent is 0.4% to 1.0% of the weight of the hydrophilic monomer containing carbon-carbon double bond.

[0023] Preferably, the mixing method is magnetic stirring at room temperature, the stirring rate is 500 rpm to 800 rpm, and the stirring time is 10 min to 30 min.

[0024] Preferably, the ultraviolet light initiation is performed at an ultraviolet light intensity of 100 mW·cm -2 ~ 150 mW·cm -2Preferably, the thermal initiation is carried out at a temperature of 55-65 DEG C, and the polymerization reaction time is 1-3 hours.

[0025] Preferably, the thermal initiation is carried out at a temperature of 55-65 DEG C, and the polymerization reaction time is 1-3 hours.

[0026] A fire warning device comprising the ion-type thermoelectric gel material.

[0027] The principle of the present application: the ion-type thermoelectric gel material of the present application comprises a skeleton formed by a hydrophilic polymer and a gel network formed by a bio-based polymer, and the thermoelectric conversion performance and the fire warning function are mainly realized by the internal electron Seebeck effect and the ion thermal diffusion effect of the gel material under temperature difference. When a certain temperature gradient exists in the gel material, the holes / electrons in the electron-type thermoelectric material dispersed in the gel material migrate directionally and accumulate at the cold end, and the free electrolyte anions and cations can migrate from the hot end to the cold end under the action of the temperature gradient and accumulate at the cold end. Due to the strong static interaction groups such as sulfonate and carboxylate on the gel network, the gel system shows strong cation selectivity, and the strong static interaction between the gel network and the electron-type thermoelectric material further increases the migration difference of the free anions and cations. The migration speed of the electrolyte cations is faster, while the migration of the anions is blocked, and the positive charge accumulated at the cold end is more, so that the internal electric potential of the gel material is inconsistent, resulting in a thermoelectric potential difference, finally giving the gel material system high thermoelectric efficiency. In addition, the electrons / holes can further drift under the induced electric field generated by the thermal diffusion of anions and cations, further increasing the ionic thermoelectric current of the gel material. Through the synergistic effect of the two thermoelectric conversion mechanisms of electrons and ions in the gel material under temperature difference, the gel material has high thermoelectric conversion performance and can generate electron flow directly supplied to the external circuit, which makes up for the defects of the traditional electron-type or ion-type thermoelectric material in the external power supply mode, and greatly expands the application scenarios of thermoelectric conversion materials.

[0028] The ion-type thermoelectric gel material of the present application has the advantages of excellent thermoelectric conversion performance, excellent flame retardant performance, good flexibility, etc., and can directly and sustainably supply power to external circuit electronic elements, and is suitable for use in intelligent fire fighting, energy storage devices, low-grade waste heat collection and conversion, etc.

[0029] Specifically:

[0030] 1) The ion-type thermoelectric gel material of the present application has high efficient flame retardant performance and sensitive fire warning function, and can continuously and repeatedly trigger the warning under abnormally high temperature, timely reminding people of the abnormally high temperature and fire risk, so as to kill the fire in the bud, and the ion-type thermoelectric gel material can also resist the flame burning for a long time in a high-oxygen environment, showing high fire safety;

[0031] 2) The ion-type thermoelectric gel material of the present application realizes excellent thermoelectric conversion performance through the electron-ion coupling thermoelectric conversion mechanism, and can directly and sustainably supply power to external circuit electronic elements through thermoelectric conversion, and is suitable for use in the fields of intelligent fire fighting, energy storage devices, low-grade waste heat collection and conversion, etc.

[0032] 3) The ion-type thermoelectric gel material of the present application benefits from the unique cation selectivity of the system, the difference in the migration of free anions and cations inside the gel is increased, further increasing its ion thermoelectric conversion performance and enhancing its thermoelectric efficiency.

[0033] 4) The ion-type thermoelectric gel material of the present application has a simple preparation method, the raw materials are cheap and easy to obtain, and is easy to apply, suitable for large-scale industrial production and application. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 It is the flexibility test result graph of the ion-type thermoelectric gel material in Example 1.

[0035] Figure 2 It is the Seebeck coefficient column chart of the gel materials in Examples 1-9 and Comparative Examples 1-2.

[0036] Figure 3 It is the fire warning test video screenshot of the gel materials in Example 1 and Comparative Example 1.

[0037] Figure 4 It is the external power supply test real-time voltage curve of the gel materials in Example 1 and Comparative Example 2. DETAILED DESCRIPTION

[0038] The present application will be further explained and described below in conjunction with specific embodiments.

[0039] The electronic-type thermoelectric materials poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid (product model number: P191136), polyaniline (product model number: P169039) and polypyrrole (product model number: P476184) in Examples 1-9 and Comparative Examples 1-2 are all purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., and the above-mentioned electronic-type thermoelectric materials need to be dispersed with deionized water to prepare a water dispersion liquid with a mass fraction of 1.5% for use.

[0040] Example 1:

[0041] An ion-type thermoelectric gel material, the preparation method thereof is as follows:

[0042] 0.2g of sodium alginate was dissolved in 11.8g of water to prepare a sodium alginate solution (transparent and uniform). The stirring speed was 500rpm and the stirring time was 14h. Then, 2g of acrylamide, 2g of 1.5% poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid aqueous dispersion, 0.5g of sodium chloride, 50mg of ammonium persulfate and 10mg of N,N'-methylenebisacrylamide were added and stirred evenly to prepare a precursor solution. The stirring speed was 600rpm and the stirring time was 30min. Then, the solution was placed in a forced-air oven at 65℃ for 1h to obtain the ionic thermoelectric gel material.

[0043] The flexibility test results of the ionic thermogel material in this embodiment are as follows: Figure 1 As shown.

[0044] Depend on Figure 1 It can be seen that ionic thermogel materials exhibit excellent flexibility and can withstand external force deformations such as bending 180°, twisting, and knotting, thus meeting the flexibility requirements as a solid flexible electrolyte.

[0045] Example 2:

[0046] An ionic thermoelectric gel material is prepared by the following method:

[0047] 0.5 g of sodium carboxymethyl cellulose was dissolved in 11.5 g of water to prepare a sodium carboxymethyl cellulose solution (clear and homogeneous). The stirring speed was 700 rpm for 20 h. Then, 1 g of acrylic acid, 1.5 g of acrylamide, 0.5 g of 1.5% polyaniline aqueous dispersion, 0.5 g of potassium chloride, 50 mg of 2-hydroxy-2-methylphenylacetone, and 10 mg of ethylene glycol dimethacrylate were added and stirred until homogeneous to prepare a precursor solution. The stirring speed was 500 rpm for 10 min. Finally, the solution was placed in a UV curing chamber at a UV light intensity of 100 mW·cm². -2 Irradiation for 10 minutes under the specified conditions yields an ionic thermoelectric gel material.

[0048] Example 3:

[0049] An ionic thermoelectric gel material is prepared by the following method:

[0050] A sodium carboxymethyl cellulose solution (transparent and uniform) was prepared by stirring and dissolving 1 g of sodium carboxymethyl cellulose in 11 g of water at a stirring rate of 800 rpm for 24 h. Then, 1.5 g of 2-acrylamido-2-methylpropanesulfonic acid, 1 g of a polypyrrole aqueous dispersion with a mass fraction of 1.5%, 0.5 g of sodium sulfate, 50 mg of ammonium persulfate, and 10 mg of N,N'-methylenebisacrylamide were uniformly stirred to prepare a precursor solution at a stirring rate of 800 rpm for 30 min. The precursor solution was then placed in a blast oven and reacted at 55°C for 3 h to obtain the ionic thermoelectric gel material.

[0051] Example 4:

[0052] An ionic thermoelectric gel material was prepared by the following method:

[0053] A sodium carboxymethyl cellulose solution (transparent and uniform) was prepared by stirring and dissolving 0.3 g of sodium carboxymethyl cellulose in 11.7 g of water at a stirring rate of 800 rpm for 14 h. Then, 1 g of acrylic acid, 1.5 g of a poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid aqueous dispersion with a mass fraction of 1.5%, 0.5 g of potassium sulfate, 25 mg of ammonium persulfate, 25 mg of 2-hydroxy-2-methylpropiophenone, and 10 mg of N,N'-methylenebisacrylamide were uniformly stirred to prepare a precursor solution at a stirring rate of 500 rpm for 20 min. The precursor solution was then irradiated in an ultraviolet light curing box at an ultraviolet light intensity of 150 mW·cm -2 for 15 min to obtain the ionic thermoelectric gel material.

[0054] Example 5:

[0055] An ionic thermoelectric gel material was prepared by the following method:

[0056] A sodium alginate solution (transparent and uniform) was prepared by stirring and dissolving 1 g of sodium alginate in 11 g of water at a stirring rate of 500 rpm for 14 h. Then, 2 g of acrylamide, 1.5 g of a polypyrrole aqueous dispersion with a mass fraction of 1.5%, 0.5 g of sodium chloride, 50 mg of ammonium persulfate, and 10 mg of N,N'-methylenebisacrylamide were uniformly stirred to prepare a precursor solution at a stirring rate of 800 rpm for 20 min. The precursor solution was then placed in a blast oven and reacted at 60°C for 2 h to obtain the ionic thermoelectric gel material.

[0057] Example 6:

[0058] An ionic thermoelectric gel material was prepared by the following method:

[0059] A sodium carboxymethyl cellulose solution (transparent and uniform) was prepared by stirring and dissolving 0.5 g of sodium carboxymethyl cellulose in 11.5 g of water at a stirring rate of 600 rpm for 20 h. Then, 1.5 g of acrylic acid, 0.5 g of 2-acrylamide-2-methylpropanesulfonic acid, 1 g of a polyaniline aqueous dispersion solution with a mass fraction of 1.5%, 0.5 g of potassium chloride, 50 mg of 2-hydroxy-2-methylpropiophenone, and 10 mg of ethylene glycol dimethacrylate were uniformly stirred to prepare a precursor solution at a stirring rate of 500 rpm for 10 min. The precursor solution was irradiated in an ultraviolet light curing box for 10 min under the condition of an ultraviolet light intensity of 100 mW·cm -2 , and an ionic thermoelectric gel material was obtained.

[0060] Example 7

[0061] An ionic thermoelectric gel material was prepared by the following method:

[0062] A sodium alginate solution (transparent and uniform) was prepared by stirring and dissolving 1 g of sodium alginate in 11 g of water at a stirring rate of 800 rpm for 24 h. Then, 1.5 g of acrylamide, 0.5 g of acrylic acid, 2 g of a polyaniline aqueous dispersion solution with a mass fraction of 1.5%, 0.5 g of sodium sulfate, 50 mg of ammonium persulfate, and 10 mg of N,N'-methylenebisacrylamide were uniformly stirred to prepare a precursor solution at a stirring rate of 700 rpm for 20 min. The precursor solution was reacted in a blast drying oven at 55°C for 3 h, and an ionic thermoelectric gel material was obtained.

[0063] Example 8

[0064] An ionic thermoelectric gel material was prepared by the following method:

[0065] A sodium carboxymethyl cellulose solution (transparent and uniform) was prepared by stirring and dissolving 0.5 g of sodium carboxymethyl cellulose in 11.5 g of water at a stirring rate of 600 rpm for 20 h. Then, 1 g of acrylic acid, 1.5 g of 2-acrylamide-2-methylpropanesulfonic acid, 1 g of a poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid aqueous dispersion solution with a mass fraction of 1.5%, 0.5 g of potassium sulfate, 25 mg of ammonium persulfate, 25 mg of 2-hydroxy-2-methylpropiophenone, and 10 mg of N,N'-methylenebisacrylamide were uniformly stirred to prepare a precursor solution at a stirring rate of 500 rpm for 20 min. The precursor solution was irradiated in an ultraviolet light curing box for 15 min under the condition of an ultraviolet light intensity of 150 mW·cm -2 , and an ionic thermoelectric gel material was obtained.

[0066] Example 9

[0067] An ionic thermoelectric gel material is prepared by the following method:

[0068] Dissolve 1 g of sodium alginate in 11 g of water to form a sodium alginate solution (transparent and uniform), at a stirring rate of 800 rpm for 20 h. Then, add 1 g of acrylamide, 1.5 g of 2-acrylamido-2-methylpropanesulfonic acid, 1 g of a polypyrrole water dispersion with a mass fraction of 1.5%, 0.5 g of sodium chloride, 25 mg of ammonium persulfate, 25 mg of 2-hydroxy-2-methylpropionphenone, and 10 mg of N,N'-methylenebisacrylamide to form a precursor solution, at a stirring rate of 500 rpm for 20 min. Then, place the precursor solution in a blast oven and react at 60°C for 2 h to obtain the ionic thermoelectric gel material.

[0069] Comparative Example 1:

[0070] An electronic thermoelectric gel material is prepared by the following method:

[0071] Dissolve 0.2 g of sodium alginate in 11.8 g of water to form a sodium alginate solution (transparent and uniform), at a stirring rate of 500 rpm for 14 h. Then, add 2 g of acrylamide, 2 g of a poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid water dispersion with a mass fraction of 1.5%, 30 mg of ammonium persulfate, and 10 mg of N,N'-methylenebisacrylamide to form a precursor solution, at a stirring rate of 600 rpm for 30 min. Then, place the precursor solution in a blast oven and react at 65°C for 1 h to obtain the electronic thermoelectric gel material.

[0072] Comparative Example 2:

[0073] An ionic thermoelectric gel material is prepared by the following method:

[0074] Dissolve 0.2 g of sodium alginate in 11.8 g of water to form a sodium alginate solution (transparent and uniform), at a stirring rate of 500 rpm for 14 h. Then, add 2 g of acrylamide, 0.5 g of sodium chloride, 30 mg of ammonium persulfate, and 10 mg of N,N'-methylenebisacrylamide to form a precursor solution, at a stirring rate of 600 rpm for 30 min. Then, place the precursor solution in a blast oven and react at 65°C for 1 h to obtain the ionic thermoelectric gel material.

[0075] Performance test:

[0076] Test method:

[0077] Tensile test: The mechanical tensile machine (Mark-10, ESM303) was used to test the gel material samples at room temperature with a tensile rate of 40 mm / min -1 , and the corresponding tensile strength-elongation at break curve was recorded. The size of the gel material sample was 50 mm x 10 mm x 1 mm.

[0078] Vertical combustion test: Based on the ANSI / UL 94-2010 test standard, the gel material sample was placed 20 mm above the propane Bunsen burner, the bottom of the gel material sample contacted the Bunsen burner flame, the flame length was 40 mm, and after burning for 20 s twice, the Bunsen burner was removed, and the combustion phenomenon and data were recorded. The size of the gel material sample was 80 mm x 10 mm x 1 mm.

[0079] Limiting oxygen index test: Based on the ASTM D2863-09 test standard, the oxygen index tester (JF-3, Nanjing Jiangning Analysis Instrument Co., Ltd.) was used to test the gel material sample. When the gel material sample burned to 50 mm from the top of the flame source at 3 min, the oxygen index at this time was recorded as the limiting oxygen index. The size of the gel material sample was 100 mm x 10 mm x 1 mm.

[0080] Seebeck coefficient test: The test platform was composed of two Peltiers, a direct current power supply, a thermocouple, a copper foil electrode, and a digital multimeter (Keithley, DMM6500 6 1 / 2). The distance between the two Peltiers was 30 mm. One of the Peltiers was powered by a direct current power supply to generate a temperature difference between the two ends of the sample. The temperature of the two Peltiers was recorded by a thermocouple. The gel material sample was placed evenly on the two Peltiers, and the copper foil electrode was connected to the digital multimeter by a wire. The size of the gel material sample was 40 mm x 10 mm x 1 mm.

[0081] Fire warning test: The gel material sample was connected to the digital multimeter (Keithley, DMM6500 6 1 / 2) and the millivolt voltage alarm by a wire, and the alarm voltage was set to 50 mV. The gel material sample was placed 20 mm above the alcohol lamp, and the sample contacted the outer flame of the alcohol lamp with a flame height of 40 mm. The fire warning time and voltage curve were recorded. The size of the gel material sample was 40 mm x 10 mm x 1 mm.

[0082] External power supply test: the test circuit was constructed by a Peltier, a voltage amplifier, a protective resistor, a load bulb (rated voltage 2.5 V), a thermocouple, a copper foil electrode, a digital multimeter (Keithley, USA, model: DMM65006 1 / 2) and a glass slide. The gel material test sample was placed in the middle of the Peltier, and the copper foil electrode, the thermocouple, the voltage amplifier, the protective resistor and the load bulb were connected by wires. The voltage across the bulb was recorded by the digital multimeter. The size of the gel material test sample was 10 mm x 10 mm x 1 mm.

[0083] Specific tests:

[0084] 1) The gel material test samples in Examples 1-9 and Comparative Examples 1-2 were cut to the appropriate size, and then subjected to mechanical tensile test, vertical burning test, limiting oxygen index test, Seebeck coefficient test and fire warning test. The test results are as follows:

[0085] a) The Seebeck coefficient column chart of the gel materials in Examples 1-9 and Comparative Examples 1-2 is shown in Figure 2

[0086] b) The fire warning test video screenshots of the gel materials in Example 1 and Comparative Example 1 are shown in Figure 3 (a is the fire warning test video screenshot of the gel material in Comparative Example 1, and b is the fire warning test video screenshot of the gel material in Example 1);

[0087] c) The tensile strength, elongation at break, Seebeck coefficient and electrical conductivity of the gel materials in Examples 1-9 and Comparative Examples 1-2 are shown in the following table:

[0088] Table 1 Tensile strength, elongation at break, Seebeck coefficient and electrical conductivity test results of gel materials

[0089]

[0090] d) The limiting oxygen index, vertical burning self-extinguishing time and repeated fire warning test results of the gel materials in Examples 1-9 and Comparative Examples 1-2 are shown in the following table:

[0091] Table 2 Limiting oxygen index, vertical burning self-extinguishing time and repeated fire warning test results of gel materials

[0092]

[0093]

[0094] From Table 1, it can be seen that the gel materials in Examples 1-9 exhibit high mechanical strength and excellent mechanical tensile properties, meeting the mechanical strength requirements as solid-state flexible electrolytes.​

[0095] From Table 1 and Table 2, it can be seen that the gel materials in Examples 1-9 all have excellent ion thermoelectric conversion performance and flame retardant performance, and also exhibit good electrical conductivity and fire warning capability, and have very broad application prospects in energy storage devices and intelligent fire fighting fields, etc.

[0096] From Table 1 and Figure 2 it can be seen that the gel materials in Examples 1-9 have a relatively high Seebeck coefficient, rely on the coupling and synergistic effect of the ion thermal diffusion effect of the free anion and cation of the electrolytic salt and the electronic Seebeck effect of the electronic thermoelectric material, and the holes and electrons of the electronic thermoelectric material undergo directional migration under a certain temperature difference, while the anions and cations inside the gel material undergo directional migration, generating a larger thermoelectric voltage, so that the gel material has excellent thermoelectric conversion capability. In addition, the electrons / holes can further drift under the induced electric field generated by the ion thermal diffusion, thereby increasing the ion thermoelectric current. The Seebeck coefficient of the gel material in Comparative Example 1 (containing only electronic thermoelectric material) is only 0.18 mV·K -1 The Seebeck coefficient of the gel material in Comparative Example 2 (containing only water-soluble electrolytic salt) is only 6.45 mV·K -1 While the Seebeck coefficient of the gel material in Example 1 is as high as 8.25 mV·K -1 , indicating that the ion thermal diffusion effect plays a dominant role in the thermoelectric conversion performance of the system, and endows it with excellent thermoelectric conversion performance. With the introduction of the electronic thermoelectric material, an electronic skeleton is constructed inside the gel, so that ion thermal diffusion and electronic Seebeck effect are realized under a temperature difference. The two effects are coupled and synergistically act, further increasing the thermoelectric efficiency of the gel, and solving the problem of low thermoelectric voltage generated by traditional electronic thermoelectric conversion materials.

[0097] From Table 2 and Figure 3 it can be seen that the gel materials in Examples 1-9 and Comparative Examples 1-2 all can exhibit high flame retardant performance of UL-94 V-0 level. After being burned by the flame for 10 s twice, the gel materials can still retain most of the gel structure, because in a high temperature environment or when encountering a flame, the water in the gel material evaporates quickly, and produces difficult-to-burn gases such as ammonia, achieving oxygen and heat insulation. In addition, the gel skeleton carbonizes at high temperature, forming a dense carbon layer, thereby exhibiting high flame retardant effect. After encountering a flame, compared with the electronic thermoelectric gel material in Comparative Example 1, the gel material in Example 1 rapidly generates a thermoelectric voltage, and the voltage value can exceed 50 mV in about 2 s, successfully triggering the fire warning device, which is mainly because the free anions and cations inside the gel material undergo directional migration and accumulate at the low temperature end. Due to the different migration rates and migration quantities of the anions and cations, a voltage of mV·K -1a thermal potential difference of 50 mV, and the electronic thermoelectric material skeleton in the gel material generates an electronic Seebeck effect under a temperature gradient to realize electronic-ion coupling thermoelectric conversion, thereby realizing fire warning. The electronic thermoelectric gel material in Comparative Example 1 can only generate electron / hole migration to produce a thermal potential difference of μV·K -1 a thermal potential difference of 50 mV, and the electronic thermoelectric material skeleton in the gel material generates an electronic Seebeck effect under a temperature gradient to realize electronic-ion coupling thermoelectric conversion, thereby realizing fire warning. The electronic thermoelectric gel material in Comparative Example 1 can only generate electron / hole migration to produce a thermal potential difference of μV·K -1 a thermal potential difference of 50 mV, and the electronic thermoelectric material skeleton in the gel material generates an electronic Seebeck effect under a temperature gradient to realize electronic-ion coupling thermoelectric conversion, thereby realizing fire warning. The electronic thermoelectric gel material in Comparative Example 1 can only generate electron / hole migration to produce a thermal potential difference of μV·K

[0098] 2) The real-time voltage curve of the gel material in Example 1 and Comparative Example 2 in the external power supply test is shown in FIG. 2. Figure 4 (An ion thermoelectric test platform is used as the basis in the present application, supplemented by a voltage amplifier and a load bulb, to construct an external power supply test circuit; a is a physical diagram of the test circuit, b is the real-time voltage curve of the gel material in Example 1 before and after the action of the voltage amplifier, and c is the real-time voltage curve of the gel material in Comparative Example 2 before and after the action of the voltage amplifier) as shown.

[0099] It can be seen that: Figure 4

[0100] a) The gel material in Comparative Example 2 can generate a thermal voltage of about 129.0 mV through internal anion and cation migration under a temperature difference, and after the voltage is amplified 19 times by the voltage amplifier, the rated voltage (about 2.5 V) of the bulb is reached, at which time the external circuit bulb is connected. Due to the double-layer effect, the electrons on the hot end plate will migrate to the cold end plate through the load, so that the plates and ionic gel electrolyte at the cold and hot ends achieve electrostatic balance, the potential difference is reduced to about 0 mV, and the external circuit outputs electrical energy. However, relying only on ionic thermal diffusion cannot achieve continuous power supply, and the external circuit bulb needs to be disconnected and the temperature difference needs to be removed, so that the internal ions of the gel gradually diffuse and return to the original disordered state. Repeating the above operation can again supply power externally;

[0101] ​b) The gel material in Example 1 can also realize the conversion of thermal energy to electrical energy in the presence of temperature difference, and can continuously output thermal voltage and current to the outside, relying on the electronic-ion coupling thermoelectric output circuit in the gel network, when the temperature difference between the two ends of the high thermoelectric performance flame-retardant ionic gel can be continuously powered reaches 20K, it can continuously generate a thermoelectric voltage of 165.0mV, at this time the connected external circuit bulb can be powered externally, the voltage generated by the thermoelectric voltage is amplified 15 times by the voltage amplifier, and the rated voltage of the bulb is 2.5V. The bulb is successfully lit, through the electronic-ion coupling thermoelectric conversion mechanism, the gel can continuously output voltage and current for more than 10min, showing good continuous power supply capacity, which is essentially different from the intermittent capacitor power supply mode of the gel material in Comparative Example 2 (traditional ionic thermoelectric conversion material), and makes up for the application defects of the traditional ionic thermoelectric conversion material;

[0102] In conclusion, the ionic thermoelectric gel material of the present application has excellent flame retardant performance and thermoelectric conversion performance. In addition, based on the electronic-ion coupling thermoelectric conversion mechanism, the ionic thermoelectric gel material of the present application has a sensitive fire warning function and a high-efficiency continuous thermoelectric conversion capability, can convert a certain temperature gradient into electrical energy, and directly and continuously supply power to electronic components, providing a new way for developing new ionic thermoelectric conversion materials.

[0103] The above examples are the preferred embodiments of the present application, but the embodiments of the present application are not limited by the above examples, any changes, modifications, substitutions, combinations, simplifications made without departing from the spirit and principles of the present application are equivalent replacement methods, and are all included in the protection scope of the present application.

Claims

1. A method for preparing an ionic thermoelectric gel material, characterized by, The method comprises the following steps: dissolving a bio-based polymer in water, adding a hydrophilic monomer containing carbon-carbon double bond, an electronic thermoelectric material, a water-soluble electrolyte, an initiator and a crosslinking agent, mixing uniformly, and then performing a free radical polymerization reaction by ultraviolet light initiation or thermal initiation, to obtain an ionic thermoelectric gel material; the ionic thermoelectric gel material comprises the following components in mass percentage: a hydrophilic polymer: 6.6%-16.1%; a bio-based polymer: 1.2%-6.7%; an electronic thermoelectric material: 0.05%-0.18%; a water-soluble electrolyte: 3.0%-3.3%; and water: 74.6%-87.5%; the hydrophilic polymer is polymerized from a hydrophilic monomer containing carbon-carbon double bond; the hydrophilic monomer containing carbon-carbon double bond is at least one of acrylamide, acrylic acid and 2-acrylamide-2-methylpropane sulfonic acid; the bio-based polymer is at least one of sodium alginate, carboxymethyl chitosan and sodium carboxymethyl cellulose; the electronic thermoelectric material is at least one of poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid, polypyrrole and polyaniline; and the water-soluble electrolyte is at least one of sodium chloride, potassium chloride, sodium sulfate and potassium sulfate. The amount of the initiator is 2.0%-5.0% of the weight of the hydrophilic monomer containing carbon-carbon double bond; and the amount of the crosslinking agent is 0.4%-1.0% of the weight of the hydrophilic monomer containing carbon-carbon double bond. The ionic thermoelectric gel material prepared by the preparation method of any one of claims 1-4 is provided.

2. The method of claim 1, wherein: The initiator is at least one of ammonium persulfate, 2-hydroxy-2-methylpropiophenone; the crosslinking agent is at least one of N,N'-methylenebisacrylamide, ethylene glycol dimethacrylate. ammonium persulfate, 2-hydroxy-2-methylpropiophenone; the crosslinking agent is at least one of N,N'-methylenebisacrylamide, ethylene glycol dimethacrylate.

3. The production method according to claim 1 or 2, characterized by: The ionic thermoelectric gel material prepared by the preparation method of any one of claims 1-4 is provided.

4. The production method according to claim 1 or 2, characterized by: The UV light initiation is performed under the condition that the UV light intensity is 100 mW·cm -2 ~ 150 mW·cm -2 , the polymerization reaction time is 10 min ~ 15 min; the thermal initiation is performed under the condition that the temperature is 55 ℃ ~ 65 ℃, the polymerization reaction time is 1 h ~ 3 h.

5. A fire warning device, characterized in that ​

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