Flexible ionic thermal battery and preparation method thereof

Abstract

The invention discloses a flexible ionic thermal battery and a preparation method thereof, the flexible ionic thermal battery comprises an ionic gel electrolyte and asymmetric electrodes, and the asymmetric electrodes are an activated carbon fiber cloth cathode and a polyaniline anode; the activated carbon fiber cloth cathode is obtained by activating carbon fiber cloth with a mixed solution of concentrated nitric acid and concentrated sulfuric acid; the ionic gel electrolyte is obtained by soaking acrylamide and acryloyloxyethyl trimethyl ammonium chloride dual-network gel in an electrolyte solution of FeCl3 / HCl. According to the flexible ionic thermal battery disclosed by the invention, a built-in potential field is constructed under a near-isothermal condition through electrode-electrolyte interface reaction characteristic difference, and decoupling of dependency of the potential field and a temperature field in a traditional quasi-solid-state ionic thermal battery is realized, so that the ionic thermal battery can finish thermal charging through near-isothermal temperature rise in an ultrathin form within 1mm, and the flexible ionic thermal battery has a wide application prospect. And stable discharge output is realized in a constant-temperature stage.

Description

Technical Field

[0001] This invention relates to the field of flexible thermoelectric conversion technology, specifically to an ultrathin flexible quasi-solid-state ion thermoelectric material, a thermal battery, and its preparation method that utilizes near-room temperature low-grade thermal energy for thermoelectric conversion based on asymmetric electrodes. Background Technology

[0002] Low-grade thermal energy (<100℃) is widely present in the natural environment, industrial production, and living organisms. Developing efficient thermoelectric conversion technologies for harvesting low-grade thermal energy to power flexible wearable electronic devices holds great potential. Compared to traditional solid-state thermoelectric conversion technologies that rely on electron-hole interactions, ion-thermal batteries based on ion thermal diffusion and thermoelectric chemical effects exhibit higher thermoelectric conversion capabilities (thermoelectric potential coefficient). S i >1 mV K -1 In particular, quasi-solid-state ion thermal batteries based on gel electrolytes have attracted widespread attention in wearable systems because they offer mechanical flexibility and integration while maintaining excellent thermoelectric performance and reducing the risk of electrolyte leakage.

[0003] In quasi-solid-state ion thermal batteries, the difference in mobility between cations and anions under a temperature gradient in the ion thermal diffusion effect imparts a high thermoelectric potential coefficient, but its capacitive operating mode limits its continuous output capability; the thermoelectrochemical effect involves ion pairs (e.g., FeCN) 3- / 4- Fe 3+ / 2+ The continuous redox reactions occurring under a temperature gradient endow quasi-solid-state ion thermal batteries with the potential for continuous power generation, but their thermoelectric potential coefficient is limited to a low value due to the finite entropy difference between ion pairs. Although strategies based on electrolyte composition design, redox ion pair concentration gradient regulation, solvation structural rearrangement, and synergistic effects have been proposed to improve the thermoelectric performance of quasi-solid-state ion thermal batteries to some extent, S i Approximately 15 mV K -1 2h continuous output energy density E 2h Approximately 500 J m -2However, existing quasi-solid-state ion thermal batteries rely on a temperature field to construct the potential field, which leads to a "thermal short circuit" that limits performance output when constructing ultra-thin devices. Specifically, traditional quasi-solid-state ion thermal batteries require the creation of a temperature gradient within the gel, utilizing the temperature difference between hot and cold electrodes to drive opposite oxidation / reduction reactions and construct the potential field between the electrodes. However, establishing an effective temperature gradient requires sufficient thermal resistance (i.e., corresponding to a large gel thickness > 5 mm), resulting in a decreased average temperature and an extended ion migration path, which inhibits the output of electrical performance. To meet the miniaturization requirements of practical wearable devices, quasi-solid-state ion thermal battery devices often need to be thin and lightweight (thickness ≤ 1 mm). This thin and lightweight design further suppresses the small temperature gradient (ΔT < 3 K) established between the skin surface and the ambient temperature, thus preventing the achievement of high-performance output in an ultra-thin form factor.

[0004] Chinese patent CN120015864A discloses an ion thermoelectric gel battery, its preparation method, and its application. The ion thermoelectric gel battery includes a metal electrode, an ion gel, and a carbon electrode; the ion gel comprises a gel matrix and a redox couple. This invention uses a metal||carbon asymmetric electrode, introducing an in-situ micro-galvanic cell effect, coupling enhanced thermoelectric chemical effects, and improving the output voltage, current density, and output power density of the ion thermoelectric battery. However, the coupling effect of its redox inert asymmetric electrode also depends on the temperature gradient constructed within the gel, and cannot solve the limitation of thermal short circuits on thermoelectric performance when the gel thickness decreases under ultra-thin dimensions; simultaneously, the irreversible erosion of its metal electrode during operation limits the stability and flexibility of its long-term output performance. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a flexible ion thermal battery with high output performance that is not limited by thickness and a method for its preparation.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A flexible ion thermal battery includes an ion gel electrolyte and an asymmetric electrode, wherein the asymmetric electrode is an activated carbon fiber cloth cathode and a polyaniline anode; The activated carbon fiber cloth cathode is obtained by activating the carbon fiber cloth with a mixed solution of concentrated nitric acid and concentrated sulfuric acid. The ion gel electrolyte is obtained by soaking an acrylamide and acryloyloxyethyltrimethylammonium chloride dual-network gel in a FeCl3 / HCl electrolyte.

[0007] The flexible ion thermal battery based on asymmetric electrodes provided by this invention utilizes pseudocapacitive electrodes and redox-active electrodes to construct a spatially biased redox reaction to generate an electric potential field. Through the adsorption of protons by oxygen-containing functional groups on the surface of the pseudocapacitive carbon fiber cloth electrode under thermal induction and the redox reaction between the redox-active polyaniline electrode and ions in the electrolyte, efficient and stable thermoelectric performance output is achieved under near-isothermal conditions inside the battery.

[0008] The preparation method of the ion gel electrolyte of the present invention is as follows: acrylamide and acryloyloxyethyltrimethylammonium chloride double network gel are placed in FeCl3 / HCl electrolyte and fully immersed to obtain quasi-solid-state ion gel electrolyte.

[0009] In the above-mentioned method for preparing ionogel electrolytes, the method for preparing the dual-network gel is as follows: 2-hydroxy-2-methylphenylacetone and polyethylene glycol diacrylate are added to a mixed solution of acrylamide and acryloyloxyethyltrimethylammonium chloride and mixed evenly to obtain a mixed solution; the mixed solution is irradiated under ultraviolet light to allow it to react fully and obtain a dual-network gel.

[0010] Furthermore, the molar concentration of acrylamide is 2~8 mol / L.

[0011] Furthermore, the mass ratio of acryloyloxyethyltrimethylammonium chloride to acrylamide is 0 to 1.

[0012] Furthermore, the molar ratio of 2-hydroxy-2-methylphenylacetone to acrylamide is 0.1 mol% to 1 mol%.

[0013] Furthermore, the molar ratio of polyethylene glycol diacrylate to acrylamide is 0.05 mol% ~ 1 mol%. Furthermore, the ultraviolet light wavelength is 365 nm or 395 nm, and the ultraviolet light irradiation time is 5 min to 60 min.

[0014] In the above-mentioned method for preparing ion gel electrolyte, the electrolyte is prepared by mixing FeCl3 and water, and then adding HCl solution to obtain the electrolyte.

[0015] Furthermore, the concentration of FeCl3 in the electrolyte is 0.05 ~ 2.0 mol / L; Furthermore, the concentration of HCl in the electrolyte is 0.01 ~ 1.0 mol / L; In the above-mentioned method for preparing ion gel electrolytes, the soaking time is greater than 12 hours.

[0016] The method for preparing the asymmetric electrode of the present invention is as follows: commercial carbon fiber cloth is activated to obtain activated carbon fiber cloth cathode, and polyaniline is loaded on activated carbon fiber cloth to obtain polyaniline anode. Activated carbon fiber cloth and polyaniline together constitute the asymmetric electrode.

[0017] In the above-mentioned method for preparing asymmetric electrodes, the method for preparing activated carbon fiber cloth is as follows: commercial carbon fiber cloth is washed sequentially with acetone, ultrapure water and ethanol, then placed in a mixed solution of concentrated nitric acid and concentrated sulfuric acid and heated to fully react, and then washed sequentially with ultrapure water and ethanol to obtain activated carbon fiber cloth.

[0018] Furthermore, the concentrated nitric acid has a mass fraction of 65% to 70%. Furthermore, the concentrated sulfuric acid has a mass fraction of 95% to 98%. Furthermore, the volume ratio of concentrated nitric acid to concentrated sulfuric acid is 1:1 to 1:4; Furthermore, the heating temperature is 70 ~ 95 ℃, and the heating time is 3 h ~ 12 h; In the above-mentioned method for preparing asymmetric electrodes, the method for preparing polyaniline electrodes is as follows: the activated carbon fiber cloth is used as the working electrode, the mercury-mercurous sulfate electrode is used as the reference electrode, and the platinum sheet electrode is used as the counter electrode. Electrochemical loading deposition is carried out in the deposition solution at a constant current density. After deposition, the electrode is thoroughly washed with ultrapure water and ethanol in sequence and then placed in a vacuum constant temperature drying oven for drying to obtain polyaniline electrodes.

[0019] Furthermore, the constant current density is 0.5 ~ 1.5 mA / cm². 2 ; Furthermore, the electrochemical loading deposition time is 10 ~ 300 min; Furthermore, the drying temperature is 20 ~ 50 ℃; Furthermore, the drying time is greater than 6 hours; In the above-mentioned method for preparing asymmetric electrodes, the deposition solution is prepared by adding aniline solution to hydrochloric acid solution and stirring thoroughly to obtain the deposition solution.

[0020] Furthermore, the molar concentration of the hydrochloric acid solution is 1 mol / L; Furthermore, the molar concentration of the aniline solution is 0.1 ~ 1.0 mol / L; Furthermore, the stirring time is greater than 10 minutes; The present invention provides a flexible thermal battery based on asymmetric electrodes, wherein the asymmetric electrodes are integrated on the same side of the gel electrolyte and in contact with the heat source, thereby obtaining a quasi-solid-state ion thermal battery.

[0021] Furthermore, the thickness of the gel electrolyte is 0.5 ~ 2 mm; Furthermore, the electrode spacing between asymmetric electrodes is 5 to 10 mm; This invention relates to a flexible ion-thermal battery that employs an activated carbon fiber cloth cathode with pseudocapacitive properties and a polyaniline anode with redox activity to form an asymmetric electrode system. Combined with an ion-gel electrolyte containing FeCl3 and HCl, an internal potential field is constructed under near-isothermal conditions through the difference in interfacial reaction characteristics between the electrode and electrolyte. By creating differences in interfacial reaction characteristics between the asymmetric electrodes, the potential field is spontaneously established during isothermal heating, solving the technical problem of traditional quasi-solid-state ion-thermal batteries struggling to form an effective temperature gradient under conditions of device thinning, thus limiting output performance.

[0022] Compared with the prior art, the present invention has the following beneficial effects: 1. Traditional quasi-solid-state ion thermal batteries rely on the internal temperature gradient of the gel to trigger a reverse redox reaction at the hot / cold ends for energy conversion. This invention proposes a near-isothermal electrochemical potential construction mechanism based on the entropy difference of the interfacial reaction. It utilizes the difference in thermo-electrochemical reaction characteristics between the asymmetric electrodes (composed of pseudocapacitive and redox-active electrodes) and the electrolyte at the same temperature during near-isothermal heating to construct a potential field. This allows a stable potential field to spontaneously form even between electrodes without an internal temperature gradient. This mechanism overcomes the dependence of traditional quasi-solid-state ion thermal batteries on constructing the potential field through the internal temperature field of the gel, achieving decoupling of heat harvesting and electrical energy release.

[0023] 2. The ion thermal battery of the present invention can achieve effective potential field construction with a thickness of no more than 1 mm, avoiding the problem that traditional ion thermal batteries must increase thickness to maintain temperature difference, so that the device still has high output performance in an ultra-thin and flexible form, significantly improving its integration adaptability in wearable systems.

[0024] 3. The ion-thermal battery utilizes the electrochemical energy generated by the built-in voltage formed through asymmetric electrodes, synergistically coupled with the thermally induced ion thermoelectric energy during the heating process. Simultaneously, it combines electrode materials with high charge storage capacity with reversible redox reactions between the electrolyte to achieve enhanced performance output. It can achieve a high voltage output of 0.1 V and 1.6 W / m² at near-human body temperature (36 ℃). 2 Maximum output power density and 1500 J / m 2 2h continuous output energy density.

[0025] 4. This invention overcomes the design bottleneck of quasi-solid-state ion thermal batteries, which involves a trade-off between lightweight design and high-performance output, through an interface control strategy of asymmetric electrodes and ion gel electrolytes. Its high-performance output at near-human body temperature and ultra-thin design provide a novel and effective flexible power supply solution for wearable flexible electronic devices, promoting the practical application of low-grade thermal energy harvesting and conversion technology. Attached Figure Description

[0026] Figure 1 This invention presents a schematic diagram of an ultrathin flexible ion thermal battery based on asymmetric electrodes. (a) is a structural schematic diagram, and (b) is a schematic diagram illustrating the working principle during heating.

[0027] 1 is an ion gel electrolyte, 2 is an activated carbon fiber cloth cathode, 3 is a polyaniline electrode anode, and 4 is a flexible encapsulation material. Figure 2 A schematic diagram of the single working cycle principle of the ultrathin flexible ion thermal battery based on asymmetric electrodes of this invention; Figure 3 The thermoelectric potential, current density, and power density of the ion thermal battery prepared in Example 1 and Comparative Example 1 of this invention are shown to change with temperature. Specifically, (a) the thermoelectric potential of the ion thermal battery prepared in Example 1 changes with temperature; (b) the current density and power density of the ion thermal battery prepared in Example 1; and (c) the thermoelectric potential of the ion thermal battery prepared in Comparative Example 1 changes with temperature.

[0028] Figure 4 Example 2 of this invention provides the thermoelectric potential, current density, and power density of an ion thermal battery as a function of temperature. (a) shows the thermoelectric potential as a function of temperature, and (b) shows the current density and power density.

[0029] Figure 5 In Example 2 of this invention, the voltage, current, output power, and energy density of an ion-ion thermal battery continuously output for 2 hours under different external resistances were obtained. Among them, (a) the output voltage and output current under an external resistance of 500Ω, (b) the output power under different external resistances, and (c) the energy density under different external resistances.

[0030] Figure 6 The present invention, in Example 2, describes a flexible wearable integrated device constructed by connecting 20 ion thermal batteries in series. (a) is a schematic diagram of the series connection, (b) is a physical image of the flexible wearable integrated device, and (c) shows the flexible wearable integrated device collecting heat from the human body to power an electronic watch.

[0031] Figure 7The performance output of the flexible wearable integrated device constructed by connecting 20 ion thermal batteries in series in Example 2 of this invention. Among them, (a) the voltage change from 5°C to 36°C, and (b) the current density and power density of the flexible wearable integrated device at 36°C. Detailed Implementation

[0032] To make the technical problem to be solved, the technical solution, and the beneficial effects of the present invention clearer, the following embodiments further illustrate the ultrathin flexible ion thermal battery based on asymmetric electrodes. Unless otherwise defined, all technical terms used herein have the same meaning as understood by one of ordinary skill in the art. These embodiments are merely illustrative and not intended to limit the scope of the invention.

[0033] This invention provides an ultrathin flexible ion thermal battery based on asymmetric electrodes, comprising an ion gel electrolyte, an activated carbon fiber cloth cathode, a polyaniline anode, and a flexible encapsulation material, the specific structure of which is as follows: Figure 1 As shown in (a). The ionogel electrolyte can be designed as a multi-faceted prism, preferably a cuboid with a thickness of 0.5 to 2 mm, according to actual needs. The activated carbon fiber cloth and polyaniline electrode are in contact with the cuboid ionogel electrolyte on the same plane and in contact with the heat source. The flexible encapsulation material is any one of waterborne polyurethane, polyimide, polydimethylsiloxane, and polyester. The ionogel electrolyte is obtained by fully immersing a double-network gel in an electrolyte containing FeCl3 and HCl for more than 12 hours.

[0034] Preferably, the dual-network gel is prepared by uniformly mixing acrylamide, acryloyloxyethyltrimethylammonium chloride, 2-hydroxy-2-methylphenylacetone, and polyethylene glycol diacrylate, followed by irradiation under 365 nm ultraviolet light for 5–60 min. The acrylamide molar concentration is 2–8 mol / L, the mass ratio of acryloyloxyethyltrimethylammonium chloride to acrylamide is 0–1, the molar ratio of 2-hydroxy-2-methylphenylacetone to acrylamide is 0.1 mol%–1 mol%, and the molar ratio of polyethylene glycol diacrylate to acrylamide is 0.05 mol%–1 mol%. Preferably, the electrolyte is obtained by mixing FeCl3 and water, and then adding HCl solution, wherein the concentration of FeCl3 is 0.05 ~ 2.0 mol / L and the concentration of HCl is 0.01 ~ 1.0 mol / L; Preferably, the activated carbon fiber cloth is obtained by sequentially washing commercial carbon fiber cloth with acetone, ultrapure water, and ethanol, then immersing it in a mixed solution of concentrated nitric acid and concentrated sulfuric acid and heating it at 70-95°C for 3-12 hours, followed by thorough washing with ultrapure water and ethanol. The concentrated nitric acid has a mass fraction of 65%-70%, the concentrated sulfuric acid has a mass fraction of 95%-98%, and the volume ratio of concentrated nitric acid to concentrated sulfuric acid is 1:~1:3. Preferably, the polyaniline electrode uses the activated carbon fiber cloth as the working electrode, a mercury-mercurous sulfate electrode as the reference electrode, and a platinum sheet electrode as the counter electrode, in the deposition solution at a current of 0.5 ~ 1.5 mA / cm². 2 Electrochemical loading deposition was performed at a constant current density for 10 to 300 minutes. After deposition, the sample was thoroughly washed with ultrapure water and ethanol in sequence, and then dried in a vacuum constant temperature drying oven at 20 to 50 °C for more than 6 hours.

[0035] Preferably, the deposition solution is obtained by adding aniline solution to hydrochloric acid solution and stirring thoroughly. The molar concentration of the hydrochloric acid solution is 1 mol / L, the molar concentration of the aniline solution is 0.1 ~ 1.0 mol / L, and the stirring time is greater than 10 min.

[0036] The working principle of the ultrathin flexible ion thermal battery based on asymmetric electrodes described in this invention is based on the differential thermoelectrochemical effect at the contact interface between the asymmetric electrodes and the ion gel electrolyte. The ion gel electrolyte consists of a three-dimensional network structure composed of a double-network hydrogel, internally loaded with an electrolyte containing FeCl3 and HCl. The asymmetric electrodes, a capacitive activated carbon fiber cloth cathode and a battery-type polyaniline anode, are assembled on the same side of the ultrathin flexible ion gel sheet, ensuring sufficient contact with the ion electrolyte while eliminating any potential temperature difference between the asymmetric electrodes. Thus, the asymmetric electrodes assembled on the same side, coupled with the sheet-like ion gel electrolyte, constitute the ultrathin flexible ion thermal battery. The complete working principle diagram is shown below. Figure 1 As shown in (b). When the ion thermal battery is at an initially low temperature T c At stage I, the Fermi level difference between the asymmetric electrodes creates an electrochemical potential difference within the battery, thus allowing the observation of an internal open-circuit voltage. V EC During the open-circuit hot charging phase (Phase II), as the ion thermal battery... T c Heat up to T h The thermal response voltage is mainly determined by the pseudocapacitive effect of the activated carbon fiber cloth, as well as the polyaniline electrode and Fe. 3 +The reaction consists of two parts: a redox reaction and a voltage. On one hand, increased temperature enhances the chemical adsorption / desorption of electrolyte ions on the surface of oxygen-containing functional groups in the activated carbon fiber cloth, inducing a pseudocapacitive reaction at the electrode-electrolyte interface. This rapid, highly reversible Faraday reaction leads to a decrease in the electrochemical potential of the activated carbon fiber cloth electrode. The decrease in voltage leads to an increase in open-circuit voltage. V oc On the other hand, the intrinsic positive temperature coefficient of the polyaniline electrode causes a slight decrease in its electrode potential upon heating; simultaneously, thermodynamically favorable Fe2+ reactions occur near the polyaniline electrode. 3+ The reduction reaction (Fe) 3+ + e - =Fe 2+ This is accompanied by the transformation of the polyaniline active material from a reduced state to an oxidized state (oxidation of the conjugated double bonds in the polymer chain), and the polyaniline electrode provides Fe. 3+ Electrons required for reduction reaction, electrode potential ( The open-circuit voltage also shows a downward trend, but it is still somewhat stronger than the initial state. After the external resistor forms a circuit (Stage III), the polyaniline electrode is further oxidized and electrons are transferred to the activated carbon fiber cloth electrode through the external circuit to form a current, thus achieving... T h The continuous power supply under these conditions. The continuous discharge capability of the ion thermal battery is mainly due to the valence state transition of the polyaniline electrode and the Fe... 3+ The combined contribution of redox reactions. The potential increases after the activated carbon fiber cloth electrode gains electrons, thus increasing the discharge voltage. V Dis As electrons accumulate, the concentration gradually decreases; simultaneously, Fe adsorbed on the surface of the oxygen-containing functional groups of the activated carbon fiber cloth... 3+ Fe is produced by consuming the accumulated electrons of CC. 2+ To some extent, it has reduced V Dis This reduces the decay rate and enhances the current output. After the discharge is complete, the external resistor is disconnected and the current is reduced to [value missing]. T c After temperature (stage IV), Fe produced in the electrolyte 2+ A thermodynamically favorable oxidation reaction (Fe) occurs. 2+ - e - = Fe 3+ The oxidized polyaniline active material is regenerated under acidic conditions, and the polyaniline electrode potential returns to its initial state. Simultaneously, ions chemically adsorbed by oxygen-containing functional groups on the activated carbon fiber cloth surface gradually desorb as the temperature decreases, and the open-circuit voltage gradually returns to its initial state, thus achieving the cyclicability of the ion thermal battery.

[0037] Example 1: Fabrication and Performance Testing of an Ultrathin Flexible Ion Thermal Battery 2.98 g of acrylamide monomer and 0.894 g of acryloyloxyethyltrimethylammonium chloride were dissolved in 7 ml of deionized water. Then, 38 µL of 2-hydroxy-2-methylphenylacetone and 15 µL of polyethylene glycol diacrylate were added, and the mixture was stirred thoroughly with a magnetic stirrer for 10 min to obtain a mixed solution. The mixed solution was transferred to a glass mold and irradiated under 365 nm ultraviolet light for 30 min to obtain a double-network gel. 0.2 ml of 3 mol / L HCl solution was added to 20 ml of 0.5 mol / L FeCl3 solution to obtain an electrolyte. The double-network gel was immersed in the electrolyte for more than 12 h to obtain an ion-gel electrolyte.

[0038] Commercial carbon fiber cloth was washed sequentially with acetone, ultrapure water, and ethanol, then placed in a mixed solution of 20 mL concentrated nitric acid (67%) and 60 mL concentrated sulfuric acid (98%), heated at 80 °C for 12 h, and then thoroughly washed with ultrapure water and ethanol to obtain activated carbon fiber cloth.

[0039] 1.46 ml of aniline solution was added to 80 ml of 1 mol / L hydrochloric acid solution, and the mixture was stirred with a magnetic stirrer for 10 min to obtain a deposition solution. The activated carbon fiber cloth was used as the working electrode, a mercury-mercurous sulfate electrode as the reference electrode, and a platinum sheet electrode as the counter electrode. The solution was then stirred at a flow rate of 1.0 mA / cm². 2 Electrochemical loading deposition was performed at a constant current density for 120 min. After deposition, the electrode was thoroughly washed with ultrapure water and ethanol, and then placed in a vacuum constant temperature drying oven and dried at 40 °C for 6 h to obtain a polyaniline electrode.

[0040] according to Figure 1 The ultrathin flexible ion thermal battery structure shown is assembled. The ultrathin flexible ion thermal battery includes the ion gel electrolyte prepared above, activated carbon fiber cloth electrodes, polyaniline electrodes, and an aqueous polyurethane flexible encapsulation material. The ion gel electrolyte has a shape of 5×20×1 mm. 3 The rectangular block shape. The activated carbon fiber cloth electrode has a shape of 5×15×0.35 mm. 3 A rectangular block. The polyaniline electrode is approximately 5 × 15 × 0.35 mm in shape. 3 The rectangular block shape. The contact area between the polyaniline electrode, the activated carbon fiber cloth electrode, and the ion gel electrolyte is 5 × 5 mm. 2 The electrode spacing is 10 mm.

[0041] The thermoelectric performance of the ultrathin flexible ion thermal battery was tested, and its thermoelectric potential changed with temperature as follows: Figure 3 As shown, by Figure 3It can be seen that the ultrathin flexible ion thermal battery has an initial potential of approximately 56 mV, and its thermoelectric potential increases with increasing heat source temperature, while the open-circuit voltage increases linearly with temperature. At a heat source temperature of 36℃, the open-circuit voltage reaches 70 mV, and the short-circuit current reaches 24 A / m. 2 The maximum output power density reaches 0.43 W / m³. 2 .

[0042] Comparative Example 1: Preparation and Performance Testing of Polyacrylamide Single-Network Gel Ion Thermal Cell A single-network gel ion thermal battery was prepared according to the method described in Example 1. The difference from Example 1 is that 0.894 g of acryloyloxyethyltrimethylammonium chloride was not added when preparing the gel, i.e., a polyacrylamide single-network gel was prepared. The other process parameters were the same as in Example 1.

[0043] The thermoelectric performance of the single-network gel ion thermal battery was tested and compared with that of Example 1 as follows: Figure 3 As shown, by Figure 3 It can be seen that both Example 1 and Comparative Example 1 have an initial potential of approximately 56 mV, and their thermoelectric potential increases with the increase of the heat source temperature, while the open-circuit voltage increases linearly with temperature. At a heat source temperature of 36°C, the open-circuit voltage reaches 70 mV. However, the short-circuit current of Comparative Example 1 is only 20 A / m. 2 The maximum output power density reaches 0.35 W / m³. 2 This indicates that the addition of acryloyloxyethyltrimethylammonium chloride enhances the conductivity of the ion gel electrolyte and strengthens the output performance of the ultrathin flexible ion thermal battery.

[0044] Example 2: Performance Optimization of Ultrathin Flexible Ion Thermal Battery 2.98 g of acrylamide monomer and 0.894 g of acryloyloxyethyltrimethylammonium chloride were dissolved in 7 ml of deionized water. Then, 38 µL of 2-hydroxy-2-methylphenylacetone and 15 µL of polyethylene glycol diacrylate were added, and the mixture was stirred thoroughly with a magnetic stirrer for 10 min to obtain a mixed solution. The mixed solution was transferred to a glass mold and irradiated under 365 nm ultraviolet light for 30 min to obtain a double-network gel. 0.2 ml of 3 mol / L HCl solution was added to 20 ml of 0.5 mol / L FeCl3 solution to obtain an electrolyte. The double-network gel was immersed in the electrolyte for more than 12 h to obtain an ion-gel electrolyte.

[0045] Commercial carbon fiber cloth was washed sequentially with acetone, ultrapure water, and ethanol, then placed in a mixed solution of 20 mL concentrated nitric acid (67%) and 60 mL concentrated sulfuric acid (98%), heated at 80 °C for 12 h, and then thoroughly washed with ultrapure water and ethanol to obtain activated carbon fiber cloth.

[0046] 1.46 ml of aniline solution was added to 80 ml of 1 mol / L hydrochloric acid solution, and the mixture was stirred with a magnetic stirrer for 10 min to obtain a deposition solution. The activated carbon fiber cloth was used as the working electrode, a mercury-mercurous sulfate electrode as the reference electrode, and a platinum sheet electrode as the counter electrode. The solution was then stirred at a flow rate of 1.0 mA / cm². 2 Electrochemical loading deposition was performed at a constant current density for 240 min. After deposition, the electrode was thoroughly washed with ultrapure water and ethanol, and then dried in a vacuum constant temperature drying oven at 40 °C for 6 h to obtain a polyaniline electrode.

[0047] according to Figure 1 The ultrathin flexible ion thermal battery structure shown is assembled. The ultrathin flexible ion thermal battery includes the ion gel electrolyte prepared above, activated carbon fiber cloth electrodes, polyaniline electrodes, and an aqueous polyurethane flexible encapsulation material. The ion gel electrolyte has a shape of 5×15×1 mm. 3 The rectangular block shape. The activated carbon fiber cloth electrode has a shape of 5×15×0.35 mm. 3 A rectangular block. The polyaniline electrode is approximately 5 × 15 × 0.35 mm in shape. 3 The rectangular block shape. The contact area between the polyaniline electrode, the activated carbon fiber cloth electrode, and the ion gel electrolyte is 5 × 5 mm. 2 The electrode spacing is 5 mm.

[0048] The thermoelectric performance of the ultrathin flexible ion thermal battery was tested, including its thermoelectric potential as a function of temperature, polarization curve, and power density. Figure 4 As shown, by Figure 4 It can be seen that, under the optimized polyaniline deposition time and electrode spacing, the ultrathin flexible ion thermal battery can achieve an open-circuit voltage of 0.1 V and a short-circuit current of 60 A / m at a heat source temperature of 36℃. 2 The maximum output power density reaches 1.6 W / m³. 2 .

[0049] Using the ultrathin flexible ion thermal battery prepared in Example 2, a circuit was formed by connecting external resistors of different resistance values. The voltage across the resistors and the current flowing through them were measured simultaneously for 2 consecutive hours. The output power and energy density were then calculated, and the results are as follows: Figure 5 As shown, by Figure 5 It can be seen that the ultrathin flexible ion thermal battery provided by the present invention has the ability to provide continuous power, and its continuous output energy density for 2 hours can reach 1500 kJ / m² when the external resistance is 500Ω. 2As can be seen, this invention utilizes the interface design and control strategy between the asymmetric electrode and the ion gel electrolyte to construct an electric potential field by leveraging the difference in thermoelectrochemical reaction characteristics at the same temperature during the heating process. This decouples the temperature field and electric potential field dependence of traditional quasi-solid-state ion thermal batteries, breaking through the design bottlenecks of thinning, effectively constructing temperature gradients, and achieving high-performance output in traditional quasi-solid-state ion thermal batteries. It provides an ultra-thin, high-performance quasi-solid-state flexible power supply solution for flexible wearable electronic devices that collects human body heat energy for thermoelectric conversion.

[0050] Furthermore, the ultrathin flexible ion thermal batteries prepared in Example 2 are connected in series to construct a flexible wearable integrated device. Twenty ultrathin flexible ion thermal batteries prepared in Example 2 are arranged according to... Figure 6 (a) As shown in the schematic diagram, the activated carbon fiber cloth electrode and the polyaniline electrode of the adjacent ultrathin flexible ion thermal battery are connected in series using conductive silver paste. Thus, they are arranged in series in the order of "carbon fiber cloth electrode—ion gel—polyaniline electrode—ion gel—carbon fiber cloth electrode" to form a structure as shown in the schematic diagram. Figure 6 (b) shows the flexible wearable integrated device. This flexible wearable integrated device can be flexibly bent to fit snugly against a person's arm, thereby absorbing low-grade heat energy from the body to supply power without relying on unstable temperature differences between the body and the environment. The flexible wearable integrated device can directly power an electronic watch by absorbing low-grade heat energy emitted from the surface of the arm. Figure 6 (c)), and it can stably output an open-circuit voltage of 1.9 V and 23 W / m at 36℃. 2 Maximum output power density ( Figure 7 ).

Claims

1. A flexible ionic thermal battery comprising an ionic gel electrolyte and asymmetric electrodes, characterized in that, The asymmetric electrode is an activated carbon fiber cloth cathode and a polyaniline anode; The activated carbon fiber cloth cathode is obtained by activating carbon fiber cloth with a mixed solution of concentrated nitric acid and concentrated sulfuric acid; The ion gel electrolyte is a double network gel of acrylamide and acryloyloxyethyl trimethyl ammonium chloride, which is obtained by soaking in an electrolyte of FeCl3 / HCl.

2. The flexible ionic thermal battery of claim 1, wherein, The method for obtaining the activated carbon fiber cloth cathode by activating carbon fiber cloth with a mixed solution of concentrated nitric acid and concentrated sulfuric acid is as follows: after the carbon fiber cloth is sequentially cleaned with acetone, ultrapure water and ethanol, the carbon fiber cloth is heated in the mixed solution of concentrated nitric acid and concentrated sulfuric acid, and then washed with ultrapure water and ethanol to obtain the activated carbon fiber cloth.

3. The flexible ionic thermal battery of claim 2, wherein, The mass fraction of concentrated nitric acid is 65% to 70%, the mass fraction of concentrated sulfuric acid is 95% to 98%, the volume ratio of concentrated nitric acid to concentrated sulfuric acid is 1:1 to 1:4, the heating temperature is 70 to 95°C, and the heating time is 3 to 12 hours.

4. The flexible ionic thermal battery of claim 1, wherein, The preparation method of the polyaniline electrode is: taking the activated carbon fiber cloth as a working electrode, taking a mercury-mercurous sulfate electrode as a reference electrode, taking a platinum sheet electrode as a counter electrode, and performing electrochemical loading deposition in a deposition solution at a constant current density to obtain; the constant current density is 0.5-1.5 mA / cm 2 , and the electrochemical loading deposition time is 10-300 min.

5. The flexible ionic thermal battery of claim 4, wherein, After deposition, the polyaniline electrode is obtained by sequentially washing with ultrapure water and ethanol and then drying in a vacuum constant-temperature drying box; the drying temperature is 20 to 50°C, and the drying time is greater than 6 hours.

6. The flexible ionic thermal battery of claim 4, wherein, Aniline solution is added to the hydrochloric acid solution, and the deposition solution is obtained after sufficient stirring; the molar concentration of the hydrochloric acid solution is 0.1 to 2 mol / L; and the molar concentration of the aniline solution is 0.1 to 1.0 mol / L.

7. The flexible ionic thermal battery of claim 1, wherein, The preparation method of the double network gel of acrylamide and acryloyloxyethyl trimethyl ammonium chloride is as follows: 2-hydroxy-2-methylpropiophenone and polyethylene glycol diacrylate are added to a mixed solution of acrylamide and acryloyloxyethyl trimethyl ammonium chloride, and the mixed solution is irradiated under ultraviolet light to obtain the double network gel.

8. The flexible ionic thermal battery of claim 7, wherein, The molar concentration of acrylamide is 2 to 8 mol / L, the mass ratio of acryloyloxyethyl trimethyl ammonium chloride to acrylamide is 0 to 1, the molar ratio of 2-hydroxy-2-methylpropiophenone to acrylamide is 0.1 mol% to 1 mol%, the molar ratio of polyethylene glycol diacrylate to acrylamide is 0.05 mol% to 1 mol%, the wavelength of the ultraviolet light is 365 nm or 395 nm, and the ultraviolet light irradiation time is 5 minutes to 60 minutes. The electrolyte is prepared by mixing FeCl3 and water and adding an HCl solution to obtain the electrolyte. The concentration of FeCl3 in the electrolyte is 0.05 to 2.0 mol / L, the concentration of HCl in the electrolyte is 0.01 to 1.0 mol / L, and the soaking time is greater than 12 hours.

9. The flexible ionic thermal battery of any one of claims 1-8, wherein, The activated carbon fiber cloth and the polyaniline electrode are assembled on the same side of the ion gel electrolyte.

10. The method of making a flexible ionic thermal battery of any of claims 1-9, characterized by: The asymmetric electrode is constructed by using the activated carbon fiber cloth and the polyaniline electrode, the ion gel electrolyte is obtained by soaking the double network gel in an electrolyte containing FeCl3 and HCl, and the ultra-thin flexible ion thermal battery is obtained by using a flexible packaging material for packaging.

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