Thermoelectric ionic gel as well as preparation method and application thereof
By optimizing the composition and preparation method of thermoelectric ion gel, a high-performance pn ion thermocouple and an electron-ion coupled thermoelectric conversion mechanism were constructed, improving the Seebeck coefficient and enhancing flame retardant properties. This solved the problem of insufficient thermoelectric and flame retardant properties, and realized a thermoelectric gel material with efficient energy storage and fire early warning capabilities.
Patent Information
- Application Number
- CN202510915433.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-03
- Publication Date
- 2025-11-28
AI Technical Summary
Existing thermoelectric ionogels have low Seebeck coefficients, poor thermoelectric properties, and flame retardant properties that are difficult to meet the requirements of practical applications.
By optimizing the composition and preparation method of the hydrophilic polymer backbone, anion and cation donors, and redox ion pairs, a high-performance pn ion thermocouple and an electron-ion coupled thermoelectric conversion mechanism were constructed to improve the Seebeck coefficient and enhance flame retardant properties.
A thermoelectric ionogel with a high Seebeck coefficient has been developed, possessing excellent ion thermoelectric properties and flame retardancy. It is suitable for thermoelectric supercapacitors, fire warning devices, and flame-retardant materials, and has sensitive overheat warning capabilities and high fire safety.
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Figure CN121022009A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of thermoelectric materials technology, specifically to a thermoelectric ion gel, its preparation method, and its application. Background Technology
[0002] Thermoelectric materials are functional materials capable of converting heat energy into electrical energy, and they have wide applications in energy conversion, temperature sensing, and fire early warning. Thermoelectric ionogels are thermoelectric materials that rely on ion conduction mechanisms. Compared to traditional thermoelectric materials that rely on electron / hole conduction, they exhibit better flexibility and demonstrate unique application potential. However, existing thermoelectric ionogels generally have low Seebeck coefficients (typically on the order of tens of microvolts per Kelvin, far lower than traditional electron / hole conduction thermoelectric materials), resulting in poor thermoelectric performance and severely limiting their application in high-efficiency thermoelectric power generation and high-sensitivity temperature sensing. Furthermore, the flame-retardant properties of existing thermoelectric ionogels are still insufficient to fully meet the growing demands of practical applications, and their flame-retardant properties need further improvement.
[0003] Therefore, developing a thermoelectric ionogel with excellent thermoelectric and flame-retardant properties is of great significance. Summary of the Invention
[0004] The purpose of this invention is to provide a thermoelectric ion gel, its preparation method, and its application.
[0005] The technical solution adopted in this invention is:
[0006] A thermoelectric ionogel comprising the following components by weight percentage:
[0007] Hydrophilic polymer backbone: 34.5%–39.6%;
[0008] Anion and cation donors: 5.0%–14.5%;
[0009] Redox ion pairs: 0.1%–1.0%;
[0010] Water: 45.0%–58.0%;
[0011] The hydrophilic polymer backbone is formed by reacting a hydrophilic linear polymer with a hydrophilic monomer containing a carbon-carbon double bond.
[0012] Preferably, the hydrophilic linear polymer is at least one of sodium carboxymethyl cellulose, polyacrylamide, polyethylene oxide, and polyvinyl alcohol.
[0013] Preferably, the number-average molecular weight of the sodium carboxymethyl cellulose is 90,000 g / mol to 250,000 g / mol.
[0014] Preferably, the number-average molecular weight of the polyacrylamide is 1,000,000 g / mol to 3,000,000 g / mol.
[0015] Preferably, the number average molecular weight of the polyethylene oxide is 50,000 g / mol to 200,000 g / mol.
[0016] Preferably, the number-average molecular weight of the polyvinyl alcohol is 80,000 g / mol to 150,000 g / mol.
[0017] Preferably, the hydrophilic monomer containing carbon-carbon double bonds is at least one of acrylic acid, acrylamide, and 2-acrylamide-2-methylpropanesulfonic acid.
[0018] Preferably, the weight ratio of the hydrophilic linear polymer to the hydrophilic monomer containing carbon-carbon double bonds is 1:1.0 to 1.7.
[0019] Preferably, the anion and cation donors are at least one of 1-butyl-3-methylimidazolium dihydrogen phosphate, choline dihydrogen phosphate, and trihexyl(tetradecyl)phosphine bis(2,4,4-trimethylpentyl)phosphonate.
[0020] Preferably, the redox ion pair is at least one of ferric chloride-ferrous chloride complex, p-benzoquinone-hydroquinone complex, and potassium ferricyanide-potassium ferrocyanide complex.
[0021] Preferably, the molar ratio of the oxidized form to the reduced form in the redox ion pair is 1:1.
[0022] A method for preparing a thermoelectric ionogel as described above includes the following steps:
[0023] 1) A mixed solution is prepared by dispersing a hydrophilic linear polymer, a hydrophilic monomer containing carbon-carbon double bonds, anionic and cationic donors, an initiator and a crosslinking agent in water, and then performing ultraviolet light-initiated polymerization or thermal initiation polymerization to obtain an ionic hydrogel;
[0024] 2) Immerse the ion hydrogel in an aqueous solution of redox ion pairs for ion exchange and age it to obtain a thermoelectric ion gel.
[0025] Preferably, a method for preparing a thermoelectric ionogel as described above includes the following steps:
[0026] 1) A hydrophilic linear polymer, a hydrophilic monomer containing carbon-carbon double bonds, anionic and cationic donors, an initiator and a crosslinking agent are stirred and dispersed in water to prepare a mixed solution. The solution is then degassed by ultrasonication and injected into a mold for UV-initiated polymerization or thermal-initiated polymerization to obtain an ionic hydrogel.
[0027] 2) Immerse the ion hydrogel in an aqueous solution of redox ion pairs for ion exchange and age it to obtain a thermoelectric ion gel.
[0028] Preferably, the initiator in step 1) is at least one of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone (UV2959) and ammonium persulfate.
[0029] Preferably, the amount of initiator used in step 1) is 0.05% to 0.25% of the weight of the hydrophilic monomer containing carbon-carbon double bonds.
[0030] Preferably, the crosslinking agent in step 1) is at least one of N,N'-methylenebisacrylamide, N,N'-bisacryloylcysteine, and polyethylene glycol bisacrylamide.
[0031] Preferably, the amount of crosslinking agent used in step 1) is 0.03% to 0.17% of the weight of the hydrophilic monomer containing carbon-carbon double bonds.
[0032] Preferably, the stirring and dispersion in step 1) is carried out at room temperature (25℃±5℃), the stirring rate is 500rpm~800rpm, and the stirring time is 1h~2h.
[0033] Preferably, the ultrasonic debubbling time in step 1) is 5 min to 15 min.
[0034] Preferably, the ultraviolet light-initiated polymerization in step 1) is carried out under ultraviolet light with an intensity of 100 mW·cm. -2 ~150mW·cm -2 The polymerization was carried out under the following conditions, with a polymerization time of 20 to 40 minutes.
[0035] Preferably, the thermally initiated polymerization in step 1) is carried out at a temperature of 55℃ to 65℃ for a polymerization time of 1h to 3h.
[0036] Preferably, the concentration of the redox ion pair in the aqueous solution of the redox ion pair in step 2) is 0.005 mol / L to 0.020 mol / L.
[0037] Preferably, the ion exchange time in step 2) is 10 min to 20 min.
[0038] Preferably, the aging process in step 2) is carried out at a temperature of 20℃~30℃ and a relative humidity of 40%~60%, and the aging time is 12h~24h.
[0039] Application of a thermoelectric ionogel as described above in the preparation of thermoelectric supercapacitors, fire warning devices, flame retardant materials or thermoelectric conversion materials.
[0040] A thermoelectric supercapacitor comprising the aforementioned thermoelectric ion gel.
[0041] A fire warning device comprising the aforementioned thermoelectric ion gel.
[0042] A flame-retardant material comprising the above-mentioned thermoelectric ionogel.
[0043] A thermoelectric conversion material comprising the above-mentioned thermoelectric ion gel.
[0044] The principle of this invention: The thermoelectric conversion performance and fire early warning function of the thermoelectric ion gel of this invention are mainly achieved through a three-pronged strategy: optimizing polymer-ion interactions, constructing high-performance pn ion thermocouples, and establishing an electron-ion coupling thermoelectric conversion mechanism. When a temperature gradient exists, holes / electrons on the hydrophilic polymer backbone undergo directional migration and accumulate at the cold end. Simultaneously, free anions and cations also migrate towards the cold end. Due to the influence of radius and electrostatic interactions, the migration rates of anions and cations differ significantly, allowing the thermoelectric ion gel to exhibit a strong ion thermoelectric effect. Furthermore, redox ion pairs at the hot and cold ends of the thermoelectric ion gel also undergo directional redox reactions. These two effects generate a potential difference in the same direction, synergistically producing a larger thermoelectric potential. Additionally, holes and electrons on the hydrophilic polymer backbone further drift under the induced electric field generated by ion thermal diffusion, increasing the ion thermocurrent of the thermoelectric ion gel. Finally, by constructing high-performance pn ion thermocouples, a thermoelectric ion gel with a high Seebeck coefficient is achieved, greatly improving the ion thermoelectric performance of the thermoelectric ion gel.
[0045] The beneficial effects of the present invention are: the thermoelectric ion gel of the present invention has both excellent ion thermoelectric properties and excellent flame retardancy, and it can achieve efficient energy storage under temperature difference, making it suitable for use in the preparation of thermoelectric supercapacitors, fire early warning devices, flame retardant materials or thermoelectric conversion materials.
[0046] Specifically:
[0047] 1) The thermoelectric ion gel of the present invention has both sensitive overheat warning capability and excellent flame retardant performance. It can issue an early warning when abnormal temperature rise is detected during the fire incubation period, which can prevent fire before it starts. Moreover, the thermoelectric ion gel can resist flame burning for a long time in a high oxygen environment, showing high fire safety.
[0048] 2) The thermoelectric ion gel of the present invention simultaneously possesses polymer-ion interaction, high-performance pn ion thermocouple and electron-ion coupling thermoelectric conversion mechanism, which significantly enhances the ion thermoelectric performance of the gel material;
[0049] 3) The thermoelectric ion gel of the present invention has good adhesion, dispersion ability and light transmittance, high versatility and wide range of applicable substrates;
[0050] 4) The preparation method of the thermoelectric ion gel of the present invention is simple, the raw materials are widely available and inexpensive, and it is suitable for large-scale industrial production and application. Attached Figure Description
[0051] Figure 1 This is a photograph of the thermoelectric ionogel from Example 1.
[0052] Figure 2 The Seebeck coefficient histograms are for the thermoelectric ionogels of Examples 1-9 and Comparative Examples 1-2.
[0053] Figure 3 The image shows the fire warning test results of the thermoelectric ionogels in Example 1 and Comparative Example 1. Detailed Implementation
[0054] The present invention will be further explained and described below with reference to specific embodiments.
[0055] Example 1:
[0056] A thermoelectric ionogel is prepared by the following method:
[0057] 1) A mixed solution was prepared by dispersing 3.2 g of polyethylene oxide (number average molecular weight 100,000 g / mol), 5 g of acrylic acid, 3 g of 1-butyl-3-methylimidazolium phosphate, 10 mg of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone, and 5 mg of N,N'-methylenebisacrylamide in 9.5 g of water at room temperature. The stirring speed was 500 rpm for 1.5 h. After ultrasonic degassing for 10 min, the solution was injected into a mold and placed in a UV curing chamber for photoinitiated polymerization for 30 min at an UV light intensity of 100 mW·cm. -2 An ionic hydrogel was obtained.
[0058] 2) The ion hydrogel was immersed in a 0.01 mol / L ferric chloride-ferrous chloride composite aqueous solution for 15 min of ion exchange. The molar ratio of ferric chloride to ferrous chloride was 1:1. Then it was aged for 24 h at a temperature of 25℃ and a relative humidity of 50% to obtain a thermoelectric ion gel.
[0059] A physical image of the thermoelectric ion gel in this embodiment is shown below. Figure 1 (The test samples are marked with a red box.)
[0060] Depend on Figure 1 It can be seen that the thermoelectric ionogel is colorless and transparent, indicating that it has excellent light transmittance.
[0061] Example 2:
[0062] A thermoelectric ionogel is prepared by the following method:
[0063] 1) 4.1 g of polyvinyl alcohol (number average molecular weight of 100,000 g / mol), 5 g of acrylic acid, 3 g of 1-butyl-3-methylimidazolium dihydrogen phosphate, 8 mg of ammonium persulfate and 5 mg of N,N'-methylenebisacrylamide were stirred and dispersed in 9.5 g of water at room temperature to prepare a mixed solution. The stirring speed was 500 rpm and the stirring time was 1.5 h. After ultrasonic degassing for 10 min, the solution was injected into a mold and then placed in a forced-air drying oven at 65 °C for thermal initiation polymerization for 2 h to obtain an ionic hydrogel.
[0064] 2) The ion hydrogel was immersed in a 0.01 mol / L ferric chloride-ferrous chloride composite aqueous solution for 15 min of ion exchange. The molar ratio of ferric chloride to ferrous chloride was 1:1. Then it was aged for 24 h at a temperature of 25℃ and a relative humidity of 50% to obtain a thermoelectric ion gel.
[0065] Example 3:
[0066] A thermoelectric ionogel is prepared by the following method:
[0067] 1) A mixed solution was prepared by dispersing 3.2 g of polyethylene oxide (number average molecular weight 100,000 g / mol), 5 g of acrylic acid, 3 g of 1-butyl-3-methylimidazolium phosphate dihydrogen phosphate, 10 mg of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone, and 5 mg of N,N'-methylenebisacrylamide in 9.5 g of water at room temperature. The stirring speed was 500 rpm for 1.5 h. After ultrasonic degassing for 10 min, the solution was injected into a mold and placed in a UV curing chamber for photoinitiated polymerization for 20 min at an UV light intensity of 150 mW·cm. -2 An ionic hydrogel was obtained.
[0068] 2) The ionized hydrogel was immersed in a 0.01 mol / L p-benzoquinone-hydroquinone composite aqueous solution for 15 min of ion exchange. The molar ratio of p-benzoquinone to hydroquinone was 1:1. Then it was aged for 24 h at a temperature of 25℃ and a relative humidity of 50% to obtain a thermoelectric ionized hydrogel.
[0069] Example 4:
[0070] A thermoelectric ionogel is prepared by the following method:
[0071] 1) 4.1 g of polyvinyl alcohol (number average molecular weight of 100,000 g / mol), 5 g of acrylic acid, 2.4 g of choline dihydrophosphate, 8 mg of ammonium persulfate and 5 mg of N,N'-methylenebisacrylamide were stirred and dispersed in 10.1 g of water at room temperature to prepare a mixed solution. The stirring speed was 600 rpm and the stirring time was 2 h. After ultrasonic degassing for 15 min, the solution was injected into a mold and placed in a forced-air drying oven at 65 °C for thermal initiation polymerization for 1.5 h to obtain ionic hydrogel.
[0072] 2) The ion hydrogel was immersed in a 0.01 mol / L ferric chloride-ferrous chloride composite aqueous solution for 15 min of ion exchange. The molar ratio of ferric chloride to ferrous chloride was 1:1. Then it was aged for 24 h at a temperature of 25℃ and a relative humidity of 50% to obtain a thermoelectric ion gel.
[0073] Example 5:
[0074] A thermoelectric ionogel is prepared by the following method:
[0075] 1) A mixed solution was prepared by dispersing 3.2 g of polyethylene oxide (number average molecular weight 100,000 g / mol), 5 g of acrylic acid, 2 g of 1-butyl-3-methylimidazolium phosphate, 10 mg of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone, and 6 mg of N,N'-bisacryloylcysteine in 10.5 g of water at room temperature. The stirring speed was 500 rpm for 2 h. After ultrasonic degassing for 10 min, the solution was injected into a mold and placed in a UV curing chamber for photoinitiated polymerization for 30 min at an UV light intensity of 100 mW·cm. -2 An ionic hydrogel was obtained.
[0076] 2) The ionized hydrogel was immersed in a 0.01 mol / L potassium ferricyanide-potassium ferrocyanide composite aqueous solution for 15 min of ion exchange. The molar ratio of potassium ferricyanide to potassium ferrocyanide was 1:1. Then it was aged for 24 h at a temperature of 25℃ and a relative humidity of 50% to obtain a thermoelectric ionized hydrogel.
[0077] Example 6:
[0078] A thermoelectric ionogel is prepared by the following method:
[0079] 1) 3.2 g of polyethylene oxide (number average molecular weight of 100,000 g / mol), 4.9 g of acrylic acid, 3 g of 1-butyl-3-methylimidazolium dihydrogen phosphate, 8 mg of ammonium persulfate and 7 mg of polyethylene glycol bisacrylamide were stirred and dispersed in 10.1 g of water at room temperature to prepare a mixed solution. The stirring speed was 700 rpm and the stirring time was 2 h. After ultrasonic degassing for 10 min, the solution was injected into a mold and then placed in a forced-air drying oven at 65 °C for thermal initiation polymerization for 1 h to obtain an ionic hydrogel.
[0080] 2) The ionized hydrogel was immersed in a 0.005 mol / L potassium ferricyanide-potassium ferrocyanide composite aqueous solution for 20 min of ion exchange. The molar ratio of potassium ferricyanide to potassium ferrocyanide was 1:1. Then it was aged for 24 h at a temperature of 25℃ and a relative humidity of 50% to obtain a thermoelectric ionized hydrogel.
[0081] Example 7:
[0082] A thermoelectric ionogel is prepared by the following method:
[0083] 1) 4.4 g of sodium carboxymethyl cellulose (number average molecular weight 150,000 g / mol), 5 g of acrylamide, 2.4 g of choline dihydrogen phosphate, 10 mg of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone, and 7 mg of polyethylene glycol bisacrylamide were dispersed in 10.1 g of water at room temperature to prepare a mixed solution. The stirring speed was 700 rpm for 1.5 h. After ultrasonic degassing for 10 min, the solution was injected into a mold and placed in a UV curing chamber for photoinitiated polymerization for 30 min at an UV light intensity of 100 mW·cm. -2 An ionic hydrogel was obtained.
[0084] 2) The ionized hydrogel was immersed in a 0.005 mol / L potassium ferricyanide-potassium ferrocyanide composite aqueous solution for 20 min of ion exchange. The molar ratio of potassium ferricyanide to potassium ferrocyanide was 1:1. Then it was aged for 24 h at a temperature of 25℃ and a relative humidity of 50% to obtain a thermoelectric ionized hydrogel.
[0085] Example 8:
[0086] A thermoelectric ionogel is prepared by the following method:
[0087] 1) 4.4 g of sodium carboxymethyl cellulose (number average molecular weight of 150,000 g / mol), 4.9 g of acrylic acid, 3 g of 1-butyl-3-methylimidazolium dihydrogen phosphate, 7.6 mg of ammonium persulfate and 7 mg of polyethylene glycol bisacrylamide were stirred and dispersed in 10.1 g of water at room temperature to prepare a mixed solution. The stirring speed was 600 rpm and the stirring time was 2 h. After ultrasonic degassing for 10 min, the solution was injected into a mold and then placed in a forced-air drying oven at 65 °C for thermal initiation polymerization for 1 h to obtain an ionic hydrogel.
[0088] 2) The ion hydrogel was immersed in a 0.01 mol / L ferric chloride-ferrous chloride composite aqueous solution for 20 min of ion exchange. The molar ratio of ferric chloride to ferrous chloride was 1:1. Then it was aged for 24 h at a temperature of 25℃ and a relative humidity of 50% to obtain a thermoelectric ion gel.
[0089] Example 9:
[0090] A thermoelectric ionogel is prepared by the following method:
[0091] 1) A mixed solution was prepared by dispersing 3.7 g of sodium carboxymethyl cellulose (number average molecular weight 150,000 g / mol), 4.6 g of acrylamide, 3.2 g of 1-butyl-3-methylimidazolium phosphate dihydrogen salt, 10 mg of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone, and 7 mg of polyethylene glycol bisacrylamide in 10.1 g of water at room temperature. The stirring speed was 800 rpm for 1.5 h. After ultrasonic degassing for 10 min, the solution was injected into a mold and placed in a UV curing chamber for photoinitiated polymerization for 30 min at an UV light intensity of 100 mW·cm. -2 An ionic hydrogel was obtained.
[0092] 2) The ionized hydrogel was immersed in a 0.005 mol / L p-benzoquinone-hydroquinone composite aqueous solution for 20 min of ion exchange. The molar ratio of p-benzoquinone to hydroquinone was 1:1. Then it was aged for 24 h at a temperature of 25℃ and a relative humidity of 50% to obtain a thermoelectric ionized hydrogel.
[0093] Comparative Example 1:
[0094] A thermoelectric ionogel (without anion or cation donors) is prepared as follows:
[0095] 1) A mixed solution was prepared by dispersing 3.2 g of polyethylene oxide (number average molecular weight 100,000 g / mol), 5 g of acrylic acid, 10 mg of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone, and 5 mg of N,N'-methylenebisacrylamide in 12.5 g of water at room temperature. The stirring speed was 500 rpm for 1.5 h. After ultrasonic degassing for 10 min, the solution was injected into a mold and placed in a UV curing chamber for photoinitiated polymerization for 30 min at an UV light intensity of 100 mW·cm. -2 An ionic hydrogel was obtained.
[0096] 2) The ion hydrogel was immersed in a 0.01 mol / L ferric chloride-ferrous chloride composite aqueous solution for 15 min of ion exchange. The molar ratio of ferric chloride to ferrous chloride was 1:1. Then it was aged for 24 h at a temperature of 25℃ and a relative humidity of 50% to obtain a thermoelectric ion gel.
[0097] Comparative Example 2:
[0098] A thermoelectric ionogel (containing no redox ion pairs) is prepared as follows:
[0099] A mixed solution was prepared by dispersing 3.2 g of polyethylene oxide (number average molecular weight 100,000 g / mol), 5 g of acrylic acid, 1 g of 1-butyl-3-methylimidazolium phosphate, 10 mg of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone, and 5 mg of N,N'-methylenebisacrylamide in 11.5 g of water at room temperature. The stirring speed was 500 rpm for 1.5 h. After ultrasonic degassing for 10 min, the solution was injected into a mold and placed in a UV curing chamber for photo-initiated polymerization for 30 min at an UV light intensity of 100 mW·cm. -2 Thermoelectric ionogel was obtained.
[0100] Performance testing:
[0101] Test method:
[0102] Tensile testing: The test samples were subjected to room temperature tensile testing using a mechanical tensile testing machine (Mark-10, USA, model: ESM303) at a tensile rate of 40 mm / min. -1 Plot the relationship curve between mechanical tensile strength and elongation at break. The size of the test sample is 50mm×10mm×1mm.
[0103] Vertical burning test: Based on the ANSI / UL 94-2010 test standard, the test sample is placed 20mm above a propane Bunsen burner, with the bottom of the test sample in contact with the Bunsen burner flame. The flame length is 40mm. The sample is burned twice for 20 seconds each time. The Bunsen burner is then removed, and the burning phenomenon and data are recorded. The dimensions of the test sample are 80mm×10mm×1mm.
[0104] Limiting oxygen index test: Based on the ASTM D2863-09 test standard, the oxygen index meter (Nanjing Jiangning Analytical Instrument Co., Ltd., model: JF-3) was used to test the test sample. When the test sample burned to 50 mm from the top of the flame source after 3 minutes, the oxygen index at this point was recorded as the limiting oxygen index. The size of the test sample was 100 mm × 10 mm × 1 mm.
[0105] Seebeck coefficient test: The test platform consists of two Peltiers, a DC power supply, thermocouples, copper foil electrodes, and a digital multimeter (Keithley, USA, model: DMM6500 6 1 / 2). The distance between the two Peltiers is 30mm. A DC power supply is used to power one of the Peltiers to generate a temperature difference between the two ends of the sample. The temperature of the two Peltiers is recorded by the thermocouple. The test sample is evenly placed on the two Peltiers, and the copper foil electrodes and the digital multimeter are connected by wires. The size of the test sample is 40mm × 10mm × 1mm.
[0106] Fire warning test: The test sample was connected to a digital multimeter (Keithley, USA, model: DMM65006 1 / 2) and a millivolt voltage alarm using wires. The alarm voltage was set to 50mV. The test sample was placed 20mm above the alcohol lamp, with the sample in contact with the outer flame of the alcohol lamp. The flame height was 40mm. The fire warning time and voltage curve were recorded. The dimensions of the test sample were 40mm×10mm×1mm.
[0107] External power supply test: The test circuit consists of a Peltier, a voltage amplifier, a protective resistor, a load bulb (rated voltage of 2.5V), a thermocouple, copper foil electrodes, a digital multimeter (Keithley, USA, model: DMM65006 1 / 2), and a glass slide. The test sample is placed in the center of the Peltier, and the copper foil electrodes, thermocouple, voltage amplifier, protective resistor, and load bulb are connected by wires. The voltage across the bulb is recorded using the digital multimeter. The dimensions of the test sample are 10mm × 10mm × 1mm.
[0108] Specific tests:
[0109] The thermoelectric ionogels of Examples 1-9 and Comparative Examples 1-2 were cut into suitable sizes as test samples, and then subjected to tensile tests, vertical burning tests, limiting oxygen index tests, Seebeck coefficient tests, fire warning tests, and external power supply tests. The test results are as follows:
[0110] a) Seebeck coefficient histograms of the thermoelectric ionogels of Examples 1-9 and Comparative Examples 1-2 are shown below. Figure 2 As shown;
[0111] b) Fire warning test results of thermoelectric ionogels in Example 1 and Comparative Example 1 (screenshot from video) Figure 3 As shown;
[0112] c) The tensile strength, elongation at break, Seebeck coefficient, and electrical conductivity of the thermoelectric ionogel are shown in the table below:
[0113] Table 1. Test results of tensile strength, elongation at break, Seebeck coefficient, and electrical conductivity.
[0114]
[0115] d) The limiting oxygen index, UL-94 rating, vertical combustion self-extinguishing time, and repeated fire warning test results of the thermoelectric ionogel are shown in the table below:
[0116] Table 2. Results of Limiting Oxygen Index, UL-94 Rating, Vertical Combustion Self-Extinguishing Time, and Repeat Fire Warning Tests
[0117]
[0118] As shown in Table 1, the thermoelectric ionogels of Examples 1 to 9 all exhibit excellent mechanical properties, with elongation at break exceeding 1100% (the highest approaching 1800%). They can also quickly recover their original shape after being subjected to tensile strain exceeding 600%, have strong vertical load-bearing capacity, and excellent tensile resilience. Their mechanical properties far exceed the basic requirements for solid flexible electrolytes.
[0119] As shown in Tables 1 and 2, the thermoelectric ionogels of Examples 1 to 9 all have excellent flame retardant properties and excellent ion thermoelectric properties. Furthermore, the capacitor devices made from the thermoelectric ionogels have sensitive fire early warning capabilities and have a very broad application prospect in the fields of energy recovery and fire safety.
[0120] From Table 1 and Figure 2 It can be known that:
[0121] i) Examples 1-9 demonstrate excellent ionic thermoelectric properties of thermoelectric ion gels prepared through a three-pronged strategy: optimizing polymer-ion interactions, constructing high-performance pn ion thermocouples, and establishing an electron-ion coupling thermoelectric conversion mechanism. In the presence of a temperature gradient, holes / electrons on the hydrophilic polymer backbone undergo directional migration and accumulate at the cold end. Simultaneously, free anions and cations also migrate towards the cold end. Due to the influence of radius and electrostatic interactions, the migration rates of anions and cations differ significantly, resulting in a strong ionic thermoelectric effect in the thermoelectric ion gel. Furthermore, redox ion pairs at the hot and cold ends of the thermoelectric ion gel also undergo directional redox reactions. These two effects generate a potential difference in the same direction, synergistically producing a larger thermoelectric potential. Additionally, holes and electrons on the hydrophilic polymer backbone further drift under the induced electric field generated by ionic thermal diffusion, increasing the ionic thermocurrent of the thermoelectric ion gel. Finally, the construction of high Seebeck coefficient thermoelectric ion gels through the construction of high-performance pn ion thermocouples significantly improves the ionic thermoelectric performance of the thermoelectric ion gel.
[0122] ii) The Seebeck coefficients of the thermoelectric ionogel of Comparative Example 1 (without anion or cation donors) and the thermoelectric ionogel of Comparative Example 2 (without redox ion pairs) are only -0.17 mV·K. -1 and -6.15mV·K -1 This is far lower than the Seebeck coefficient of the thermoelectric ionogel in Example 1, which is -12.25 mV·K. -1 This indicates that the ion thermal diffusion effect plays a dominant role in the thermoelectric conversion performance of this system, which endows the thermoelectric ion gel with excellent thermoelectric conversion performance. With the introduction of redox ion pairs, they carry out directional redox reactions at the hot and cold ends of the material and generate a potential difference between the hot and cold ends. Higher ion thermoelectric performance can be achieved through the thermocurrent effect combined with the ion thermal diffusion effect.
[0123] From Table 2 and Figure 3 It can be seen that the thermoelectric ionogels of Examples 1-9 and Comparative Examples 1-2 all achieved a UL-94 flame retardancy rating of V-0, exhibiting high flame retardant performance. Furthermore, the thermoelectric ionogels of Examples 1-9 maintained a largely intact structure after being subjected to two 10-second flame burns, with charring only occurring at the flame source. This is because when exposed to flame, the evaporation of moisture in the gel carries away a significant amount of heat. As combustion progresses, the gel generates flammable gases such as NH3 and decomposes to produce free radicals that quench highly reactive free radicals such as H· and HO· in the gas phase, effectively slowing down the combustion reaction in the gas phase. In addition, the anions and cations also participate in the char formation reaction, forming a dense char layer with higher thermal stability and more conjugated structures. This effectively blocks the transfer of heat and oxygen within the gel, inhibiting further degradation of the gel network and improving the flame retardant performance of the gel.
[0124] In summary, the thermoelectric ion gel prepared by this invention through a three-pronged strategy of optimizing polymer-ion interactions, constructing high-performance pn ion thermocouples, and establishing an electron-ion coupling thermoelectric conversion mechanism possesses both excellent flame retardant properties and excellent thermoelectric conversion performance. Furthermore, the thermoelectric ion gel also has a sensitive fire early warning function and a highly efficient and continuous thermoelectric conversion capability, thus expanding the application range of ion thermoelectric conversion materials.
[0125] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.
Claims
1. A thermoelectric ionogel, characterized in that, Includes the following components by weight percentage: Hydrophilic polymer backbone: 34.5%–39.6%; Anion and cation donors: 5.0%–14.5%; Redox ion pairs: 0.1%–1.0%; Water: 45.0%–58.0%; The hydrophilic polymer backbone is formed by reacting a hydrophilic linear polymer with a hydrophilic monomer containing a carbon-carbon double bond.
2. The thermoelectric ionogel according to claim 1, characterized in that: The hydrophilic linear polymer is at least one of sodium carboxymethyl cellulose, polyacrylamide, polyethylene oxide, and polyvinyl alcohol; the hydrophilic monomer containing carbon-carbon double bonds is at least one of acrylic acid, acrylamide, and 2-acrylamido-2-methylpropanesulfonic acid.
3. The thermoelectric ionogel according to claim 1 or 2, characterized in that: The weight ratio of the hydrophilic linear polymer to the hydrophilic monomer containing carbon-carbon double bonds is 1:1.0 to 1.
7.
4. The thermoelectric ionogel according to claim 1 or 2, characterized in that: The anion and cation donors are at least one of 1-butyl-3-methylimidazolium dihydrogen phosphate, choline dihydrogen phosphate, and trihexyl(tetradecyl)phosphine bis(2,4,4-trimethylpentyl)phosphonate.
5. The thermoelectric ionogel according to claim 1 or 2, characterized in that: The redox ion pair is at least one of ferric chloride-ferrous chloride complex, p-benzoquinone-hydroquinone complex, and potassium ferricyanide-potassium ferrocyanide complex.
6. A method for preparing a thermoelectric ionogel as described in any one of claims 1 to 5, characterized in that, Includes the following steps: 1) A mixed solution is prepared by dispersing a hydrophilic linear polymer, a hydrophilic monomer containing carbon-carbon double bonds, anionic and cationic donors, an initiator and a crosslinking agent in water, and then performing ultraviolet light-initiated polymerization or thermal initiation polymerization to obtain an ionic hydrogel; 2) Immerse the ion hydrogel in an aqueous solution of redox ion pairs for ion exchange and age it to obtain a thermoelectric ion gel.
7. The preparation method according to claim 6, characterized in that: The initiator in step 1) is at least one of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone and ammonium persulfate; the amount of the initiator in step 1) is 0.05% to 0.25% of the weight of the hydrophilic monomer containing carbon-carbon double bonds; the crosslinking agent in step 1) is at least one of N,N'-methylenebisacrylamide, N,N'-bisacryloylcysteine, and polyethylene glycol bisacrylamide; the amount of the crosslinking agent in step 1) is 0.03% to 0.17% of the weight of the hydrophilic monomer containing carbon-carbon double bonds.
8. The preparation method according to claim 6 or 7, characterized in that: Step 1) The ultraviolet light-initiated polymerization is carried out under ultraviolet light intensity of 100 mW·cm. -2 ~150mW·cm -2 The polymerization is carried out under the following conditions, with a polymerization time of 20 min to 40 min; the thermally initiated polymerization in step 1) is carried out at a temperature of 55℃ to 65℃ for a polymerization time of 1 h to 3 h.
9. The preparation method according to claim 6 or 7, characterized in that: The ion exchange time in step 2) is 10 min to 20 min; the aging in step 2) is carried out at a temperature of 20℃ to 30℃ and a relative humidity of 40% to 60%, and the aging time is 12 h to 24 h.
10. The application of a thermoelectric ionogel as described in any one of claims 1 to 5 in the preparation of thermoelectric supercapacitors, fire early warning devices, flame retardant materials or thermoelectric conversion materials.