Wide-temperature-range ionic thermal battery electrolyte, preparation method thereof and ionic thermal battery

Abstract

The application discloses a wide-temperature-range ionic thermal battery electrolyte, a preparation method thereof and an ionic thermal battery. ‑ and I3 ‑ constitute; an organic sulfoxide salt is added into the aqueous solution containing the iodine-based redox couple, and stirring is performed until flocculent precipitates are generated in situ, so that the wide-temperature-range ionic thermal battery electrolyte is obtained. ‑ The application introduces the organic sulfoxide salt into the electrolyte, the organic sulfoxide salt and I3 ‑ undergo an ionic association reaction, and flocculent precipitates of an organic complex having a heat-sensitive characteristic are formed in situ, based on a heat-sensitive precipitate phase change regulation mechanism, the flocculent precipitates inhibit heat convection while improving the ion concentration gradient at a high temperature, so that stable output of the thermoelectric conversion performance in a wide temperature range is realized, and the problems of a narrow working temperature range, attenuation of a thermoelectric voltage at a high temperature and limited Seebeck coefficient of an existing iodine-based ionic thermal battery are effectively solved.

Description

Technical Field

[0001] This invention relates to the field of ion thermal battery technology, and in particular to a wide-temperature-range ion thermal battery electrolyte, its preparation method, and the ion thermal battery itself. Background Technology

[0002] Ion thermal batteries, as an emerging thermoelectric conversion technology, utilize the migration and redox reactions of ions in an electrolyte driven by temperature differences to directly convert thermal energy into electrical energy. They offer advantages such as simple structure, low cost, and no moving parts. Among the many electrolyte systems for ion thermal batteries, those based on iodine anions (I₂) are particularly promising. - ) and iodine tri-antion (I3) - Iodine-based aqueous electrolytes for iodine-based redox couples are considered one of the most promising candidate systems due to their high conductivity, good reversibility, and environmental friendliness. However, the practical application of ion-thermal batteries is limited by the operating temperature range and thermal stability of iodine-based aqueous electrolytes. An ideal ion-thermal battery needs to maintain a stable Seebeck coefficient and output voltage over a wide temperature range. But in actual operating conditions, when the hot-end temperature exceeds 60°C, due to the intense thermal motion of ions, solvent evaporation, and side reactions at the electrode interface, the chemical potential difference across the battery is often difficult to maintain, leading to a rapid decay of the output voltage. This severely restricts its application in medium- and high-temperature scenarios such as industrial waste heat and geothermal energy.

[0003] In existing technologies, to address the issues of thermal voltage decay and limited operating temperature range in iodine-based ion thermal batteries at high temperatures, a common strategy is to introduce pure iodine crystals, iodide powders, or solid inorganic salts as hot-end buffers. The aim is to maintain the ion concentration gradient at both ends by utilizing the endothermic dissolution or phase transition process of the solid material during heating. However, these conventional thermosensitive crystalline materials suffer from a fundamental kinetic defect: they often undergo explosive and uncontrollable rapid dissolution upon heating, leading to an instantaneous supersaturation of the hot-end ion concentration. This not only fails to establish a sustained ion concentration gradient but also causes a surge in internal resistance and a sharp drop in voltage due to the intense concentration polarization effect. Consequently, battery performance reaches a bottleneck and rapidly fails around 60°C. It is completely impossible to continuously lock the chemical potential through dynamic equilibrium at the solid-liquid interface in the high-temperature range of 80°C and above. Therefore, existing electrolyte systems have consistently failed to achieve a synergistic improvement in both high Seebeck coefficient and stable voltage output across a wide temperature range.

[0004] Therefore, existing technologies still need to be improved and developed. Summary of the Invention

[0005] Based on the shortcomings of the prior art, the purpose of this invention is to provide a wide-temperature-range ion thermal battery electrolyte, its preparation method, and the ion thermal battery itself, aiming to solve the problems of narrow operating temperature range, thermal voltage decay at high temperatures, and limited Seebeck coefficient of existing iodine-based ion thermal batteries.

[0006] The technical solution of the present invention is as follows: A first aspect of the present invention provides a method for preparing a wide-temperature-range ion thermal battery electrolyte, comprising the following steps: Provide an aqueous solution containing an iodine-based redox couple; the iodine-based redox couple is composed of I - and I3 - constitute; Organic sulfoxide salts are added to the aqueous solution of the iodine-containing redox couple, and stirred until flocculent precipitate forms in situ, thus obtaining the wide-temperature-range ion thermal battery electrolyte.

[0007] Optionally, 0.05 to 0.5 mol of an organic sulfoxide salt is added to each liter of aqueous solution containing an iodine-based redox couple.

[0008] Optionally, 0.2 mol of an organic sulfoxide salt is added to each liter of aqueous solution containing an iodine-based redox couple. Optionally, the organic sulfoxide salt includes at least one selected from trimethyl sulfoxide, trimethyl sulfoxide bromide, and trimethyl sulfoxide iodide.

[0009] Optionally, the method for preparing the aqueous solution of the iodine-containing redox couple includes the following steps: A soluble alkali metal iodide and elemental iodine are added to water and dissolved to obtain an aqueous solution of the iodine-containing redox couple.

[0010] Optionally, the soluble alkali metal iodide includes at least one of potassium iodide and sodium iodide.

[0011] Optionally, in the aqueous solution of the iodine-containing redox couple, the I... - The concentration of I3 is 10 mmol / L to 500 mmol / L. - The concentration ranges from 10 mmol / L to 500 mmol / L.

[0012] In a second aspect, the present invention provides a wide-temperature-range ion thermal battery electrolyte, wherein the electrolyte is prepared by the preparation method described above.

[0013] A third aspect of the present invention provides an ion thermal battery, the ion thermal battery comprising a cold end electrode and a hot end electrode, and an electrolyte located between the cold end electrode and the hot end electrode, wherein the electrolyte comprises the wide temperature range ion thermal battery electrolyte of the present invention as described above.

[0014] Optionally, the cold end electrode and the hot end electrode are made of the same material.

[0015] Beneficial effects: This invention introduces an organic sulfoxide salt into the electrolyte, and the organic sulfoxide salt reacts with I3 - Through ion association reaction, an organic complex flocculent precipitate with thermosensitive properties (thermally controlled dissolution characteristics) is formed in situ. Based on the thermosensitive precipitation phase change regulation mechanism, the flocculent precipitate can suppress thermal convection while increasing the ion concentration gradient and chemical potential gradient at high temperature, thereby achieving stable output of thermoelectric conversion performance over a wide temperature range. This effectively solves the problems of narrow operating temperature range, thermal voltage decay at high temperature, and limited Seebeck coefficient of existing iodine-based ion thermal batteries.

[0016] Specifically, this flocculent precipitate exhibits significantly differentiated thermodynamic behavior: unlike the explosive dissolution of conventional crystals below 60°C, the flocculent precipitate of this invention maintains a slow and controllable decomposition and release kinetics (i.e., a kinetic mechanism of partially undissolved and slow, gradual decomposition) even at hot-end temperatures as high as 85°C. This unique and controllable dissolution kinetic behavior allows the flocculent precipitate to continuously release I3 into the hot-end liquid phase, much like an ion-releasing capsule. - The ions dynamically maintain the reactant concentration gradient and chemical potential gradient at the hot and cold ends at the microscopic level, suppressing the voltage decay caused by the thermal motion of ions at the hot end and solving the fundamental problem of chemical potential decay at high temperatures. Simultaneously, the physical network structure of the flocculent precipitate (i.e., a three-dimensional network structure) allows the flocculent precipitate to act as a pinning agent in the liquid phase, effectively suppressing natural thermal convection and concentration polarization under a strong temperature difference field (85℃ hot end vs. 10℃ cold end), ensuring the stability of the temperature interface and improving the Seebeck coefficient. This invention breaks through the bottleneck of high-temperature chemical potential decay in traditional iodine-based systems at the microscopic level, providing a thermodynamic driving force for a significant increase in the Seebeck coefficient.

[0017] The ion thermal battery assembled with the wide-temperature-range ion thermal battery electrolyte prepared by the method provided in this invention did not exhibit voltage saturation or degradation under extreme temperature difference conditions of 10°C at the cold end and as high as 85°C at the hot end. Instead, it showed a continuous performance growth trend, with a Seebeck coefficient reaching 1.50 mV K. -1 . Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the preparation process of the wide-temperature-range ion thermal battery electrolyte in an embodiment of the present invention.

[0019] Figure 2 The graph shows the temperature response of the ion thermal battery assembled using the wide-temperature-range ion thermal battery electrolyte in Example 1 at different temperatures.

[0020] Figure 3 The figure shows the temperature response of the ion thermal battery assembled using the electrolyte of Comparative Example 1 at different temperatures.

[0021] Figure 4 The graph shows the temperature response and calculated Seebeck coefficient of ion thermal batteries assembled using the wide-temperature-range ion thermal battery electrolyte in Example 1 and the ion thermal battery electrolyte in Comparative Example 1 at different temperatures.

[0022] Figure 5 The graph shows the temperature response and calculated Seebeck coefficient of the ion thermal battery assembled using the wide-temperature-range ion thermal battery electrolyte in Example 2 at different temperatures.

[0023] Figure 6 The graph shows the temperature response and calculated Seebeck coefficient of the ion thermal battery assembled using the wide-temperature-range ion thermal battery electrolyte in Example 3 at different temperatures.

[0024] Figure 7 The graph shows the temperature response and calculated Seebeck coefficient of the ion thermal battery assembled using the wide-temperature-range ion thermal battery electrolyte in Example 4 at different temperatures.

[0025] Figure 8 The graph shows the temperature response and calculated Seebeck coefficient of the ion thermal battery assembled using the wide-temperature-range ion thermal battery electrolyte in Example 5 at different temperatures. Detailed Implementation

[0026] This invention provides a wide-temperature-range ion thermal battery electrolyte, its preparation method, and the ion thermal battery itself. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0028] If the embodiments of this invention involve descriptions such as "first," "second," etc., these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. The embodiments of this invention provide a method for preparing a wide-temperature-range ion-thermal battery electrolyte, wherein, as... Figure 1 As shown, it includes the following steps: S1. Provide an aqueous solution containing an iodine-based redox couple; the iodine-based redox couple is composed of I... - and I3 - constitute; S2. Add the organic sulfoxide salt to the aqueous solution of the iodine-containing redox couple, and stir until a flocculent precipitate forms in situ (specifically, a uniform flocculent precipitate composed of the organic sulfoxide salt and I3). - The wide-temperature-range ion thermal battery electrolyte is obtained by generating the electrolyte through ion association reaction.

[0029] This invention introduces an organic sulfoxide salt into the electrolyte, and the organic sulfoxide salt reacts with I3 - Through ion association reaction, an organic complex flocculent precipitate with thermosensitive properties (thermally controlled dissolution characteristics) is formed in situ. Based on the thermosensitive precipitation phase change regulation mechanism, the flocculent precipitate can suppress thermal convection while increasing the ion concentration gradient and chemical potential gradient at high temperature, thereby achieving stable output of thermoelectric conversion performance over a wide temperature range. This effectively solves the problems of narrow operating temperature range, thermal voltage decay at high temperature, and limited Seebeck coefficient of existing iodine-based ion thermal batteries.

[0030] Specifically, this flocculent precipitate exhibits significantly differentiated thermodynamic behavior: unlike the explosive dissolution of conventional crystals below 60°C, the flocculent precipitate of this invention maintains a slow and controllable decomposition and release kinetics (i.e., a kinetic mechanism of partially undissolved and slow, gradual decomposition) even at hot-end temperatures as high as 85°C. This unique and controllable dissolution kinetic behavior allows the flocculent precipitate to continuously release I3 into the hot-end liquid phase, much like an ion-releasing capsule. - The ions dynamically maintain the reactant concentration gradient and chemical potential gradient at the hot and cold ends at the microscopic level, suppressing the voltage decay caused by the thermal motion of ions at the hot end and solving the fundamental problem of chemical potential decay at high temperatures. Simultaneously, the physical network structure of the flocculent precipitate (i.e., a three-dimensional network structure) allows the flocculent precipitate to act as a pinning agent in the liquid phase, effectively suppressing natural thermal convection and concentration polarization under a strong temperature difference field (85℃ hot end vs. 10℃ cold end), ensuring the stability of the temperature interface and improving the Seebeck coefficient. This invention breaks through the bottleneck of high-temperature chemical potential decay in traditional iodine-based systems at the microscopic level, providing a thermodynamic driving force for a significant increase in the Seebeck coefficient.

[0031] The ion thermal battery assembled with the wide-temperature-range ion thermal battery electrolyte prepared by the method provided in this invention did not exhibit voltage saturation or degradation under extreme temperature difference conditions of 10°C at the cold end and as high as 85°C at the hot end. Instead, it showed a continuous performance growth trend, with a Seebeck coefficient reaching 1.50 mV K. -1 .

[0032] In step S1, in some embodiments, the I in the aqueous solution of the iodine-containing redox couple... -The concentration is 10 mmol / L to 500 mmol / L (e.g., 10 mmol / L, 20 mmol / L, 50 mmol / L, 80 mmol / L, 100 mmol / L, 200 mmol / L, 300 mmol / L, 400 mmol / L, or 500 mmol / L), the I3 - The concentration is 10 mmol / L to 500 mmol / L (for example, it can be 10 mmol / L, 20 mmol / L, 50 mmol / L, 80 mmol / L, 100 mmol / L, 200 mmol / L, 300 mmol / L, 400 mmol / L or 500 mmol / L).

[0033] In step S1, in some embodiments, the method for preparing the aqueous solution of the iodine-containing redox couple includes the following steps: A soluble alkali metal iodide and elemental iodine are added to water and dissolved to obtain the iodine-containing redox couple (I0.05). - and I3 - ( ) in aqueous solution.

[0034] In this embodiment, a soluble alkali metal iodide and elemental iodine are added to water to react and produce I3. - (i.e. I - + I2= I 3- ), thus forming a structure containing I - and I3 - An aqueous solution.

[0035] In some embodiments, the molar ratio of the soluble alkali metal iodide to elemental iodine is 2:1. When the molar ratio of the soluble alkali metal iodide to elemental iodine is 2:1, the reaction can produce I3. - Meanwhile, there is still unreacted I - Thus forming a structure containing I - and I3 - An aqueous solution.

[0036] In some embodiments, the ratio of iodine to water is (10~500) mmol : 1 L, for example, it can be 10 mmol : 1 L, 20 mmol : 1 L, 50 mmol : 1 L, 80 mmol : 1 L, 100 mmol : 1 L, 200 mmol : 1 L, 300 mmol : 1 L, 400 mmol : 1 L, or 500 mmol : 1 L, etc.

[0037] In some embodiments, the soluble alkali metal iodide includes at least one of potassium iodide and sodium iodide, but is not limited thereto.

[0038] In step S2, in some embodiments, 0.05 to 0.5 mol of an organic sulfoxide salt is added to each liter of the aqueous solution containing the iodine-based redox couple. For example, 0.05 mol, 0.06 mol, 0.07 mol, 0.08 mol, 0.09 mol, 0.1 mol, 0.15 mol, 0.2 mol, 0.25 mol, 0.3 mol, 0.35 mol, 0.4 mol, 0.45 mol, or 0.5 mol of the organic sulfoxide salt can be added to each liter of the aqueous solution containing the iodine-based redox couple. This range of molar amounts allows the added organic sulfoxide salt to react with I3... - Through ion association reactions, a large amount of flocculent precipitate is generated in situ. This flocculent precipitate exhibits unique thermosensitive properties: during heating, the flocculent precipitate undergoes controllable dissolution with the temperature gradient, forming a dynamic solid-liquid interface at the heating end. This thermoinduced dissolution behavior effectively maintains the ion concentration gradient and chemical potential gradient at high temperatures, suppressing voltage decay caused by the thermal motion of ions at the hot end. Experiments show that even at a high temperature of 85℃, the system can still maintain a significant voltage response and greatly improve the Seebeck coefficient, solving the problem of high-temperature failure in traditional iodine-based ion thermal batteries.

[0039] In some embodiments, 0.2 mol of an organic sulfoxide salt is added to each liter of aqueous solution containing an iodine-based redox couple.

[0040] In some embodiments, the organic sulfoxide salt includes at least one of trimethyl sulfoxide, trimethyl sulfoxide bromide, and trimethyl sulfoxide iodide, but is not limited thereto.

[0041] This invention also provides a wide-temperature-range ion thermal battery electrolyte, which is prepared using the preparation method described above.

[0042] This invention also provides an ion thermal battery, comprising a cold-end electrode and a hot-end electrode, and an electrolyte located between the cold-end electrode and the hot-end electrode. The electrolyte comprises the wide-temperature-range ion thermal battery electrolyte described above. Ion thermal batteries assembled using the wide-temperature-range ion thermal battery electrolyte prepared according to this invention do not exhibit voltage saturation or degradation under extreme temperature difference conditions of 10°C at the cold end and as high as 85°C at the hot end; instead, they show a continuous performance increase, with a Seebeck coefficient reaching 1.50 mV·K. -1 This effectively solves the problems of narrow operating temperature range, thermal voltage decay at high temperatures, and limited Seebeck coefficient in existing iodine-based ion thermal batteries.

[0043] In some embodiments, the cold end electrode and the hot end electrode are made of the same material.

[0044] In some embodiments, both the cold-end electrode and the hot-end electrode are platinum electrodes or carbon paper electrodes.

[0045] The present invention will be further described below through specific embodiments.

[0046] In the following embodiments, unless otherwise specified, the raw materials and equipment used are all commercially available products.

[0047] Example 1 This embodiment provides a method for preparing a wide-temperature-range ion thermal battery electrolyte, including the following steps: (1) Add 4.15 g of potassium iodide and 3.17 g of elemental iodine to 250 mL of deionized water and stir continuously until the solution is clear and free of precipitate, to obtain a solution containing I. - and I3 - Aqueous solution (wherein I) - and I3 - The concentrations were all 50 mmol / L.

[0048] (2) To each liter containing I - and I3 - In an aqueous solution, 0.2 mol of trimethyl sulfoxide powder (i.e., the concentration of added trimethyl sulfoxide is 0.2 mol / L) is added, and the mixture is stirred rapidly until a uniform flocculent precipitate is formed in situ, thus obtaining a stable wide-temperature-range ion thermal battery electrolyte.

[0049] Example 2 This embodiment provides a method for preparing a wide-temperature-range ion thermal battery electrolyte, including the following steps: (1) Add 4.15 g of potassium iodide and 3.17 g of elemental iodine to 250 mL of deionized water and stir continuously until the solution is clear and free of precipitate, to obtain a solution containing I. - and I3 - Aqueous solution (wherein I) - and I3 - The concentrations were all 50 mmol / L.

[0050] (2) To each liter containing I - and I3 - Add 0.5 mol of trimethyl sulfoxide powder to the aqueous solution, and stir rapidly until a uniform flocculent precipitate is formed in situ to obtain a stable wide-temperature-range ion thermal battery electrolyte.

[0051] Example 3 This embodiment provides a method for preparing a wide-temperature-range ion thermal battery electrolyte, including the following steps: (1) Add 4.15 g of potassium iodide and 3.17 g of elemental iodine to 250 mL of deionized water and stir continuously until the solution is clear and free of precipitate, to obtain a solution containing I. - and I3 - Aqueous solution (wherein I) - and I3 - The concentrations were all 50 mmol / L.

[0052] (2) To each liter containing I - and I3 - In an aqueous solution, 0.1 mol of trimethyl sulfoxide powder was added and stirred rapidly until a uniform flocculent precipitate was formed in situ, thus obtaining a stable wide-temperature-range ion thermal battery electrolyte.

[0053] Example 4 This embodiment provides a method for preparing a wide-temperature-range ion thermal battery electrolyte, including the following steps: (1) Add 4.15 g of potassium iodide and 3.17 g of elemental iodine to 250 mL of deionized water and stir continuously until the solution is clear and free of precipitate, to obtain a solution containing I. - and I3 - Aqueous solution (wherein I) - and I3 - The concentrations were all 50 mmol / L.

[0054] (2) To each liter containing I - and I3 - Add 0.05 mol of trimethyl sulfoxide powder to the aqueous solution, and stir rapidly until a uniform flocculent precipitate is formed in situ, thus obtaining a stable wide-temperature-range ion thermal battery electrolyte.

[0055] Example 5 This embodiment provides a method for preparing a wide-temperature-range ion thermal battery electrolyte, including the following steps: (1) Add 41.5 g of potassium iodide and 31.7 g of elemental iodine to 250 mL of deionized water and stir continuously until the solution is clear and free of precipitate, to obtain a solution containing I - and I3 - Aqueous solution (wherein I) - and I3 - The concentrations were all 500 mmol / L.

[0056] (2) To the above containing I - and I3 -In an aqueous solution, 0.2 mol of trimethyl sulfoxide powder was added and stirred rapidly until a uniform flocculent precipitate was formed in situ, thus obtaining a stable wide-temperature-range ion thermal battery electrolyte.

[0057] Comparative Example 1 This comparative example provides a method for preparing an electrolyte for an ion-thermal battery, comprising the following steps: Add 4.15 g of potassium iodide and 3.17 g of elemental iodine to 250 mL of deionized water, and stir continuously until the solution is clear and free of precipitate, to obtain a solution containing I. - and I3 - Aqueous solution (wherein I) - and I3 - The concentration of each electrolyte is 50 mmol / L, which is the electrolyte for the ion thermal battery.

[0058] test: (1) The wide-temperature-range ion thermal battery electrolyte in Example 1 and the ion thermal battery electrolyte in Comparative Example 1 (i.e. containing 50 mM I) - / I3 - The test was conducted using an aqueous solution of the solution. Two platinum plates were used as the cold-end electrode and the hot-end electrode, respectively. The hot-end electrode was heated to different temperatures on a heating plate, while the cold-end electrode was maintained at room temperature. The wide-temperature-range ion thermal battery electrolyte prepared in Example 1 and the ion thermal battery electrolyte prepared in Comparative Example 1 (containing 50 mM I) were used, respectively. - / I3 - An aqueous solution was assembled into an ion-thermal battery for electrochemical performance testing. The temperature response results at different temperatures are as follows: Figure 2 and Figure 3 As shown. By Figure 2 It can be seen that the ion thermal battery assembled using the wide-temperature-range ion thermal battery electrolyte in Example 1, under the temperature difference condition of 10°C at the cold end and the hot end temperature slowly increasing from 10°C to 85°C, did not exhibit voltage saturation or degradation, showing a continuous performance growth trend; while the ion thermal battery electrolyte in Comparative Example 1 (containing 50 mM I) - / I3 - An ion thermal battery assembled with an aqueous solution, when the hot end temperature exceeds 60°C, such as Figure 3 As shown, due to natural thermal convection and concentration polarization under a strong temperature difference field, the voltage exhibits significant fluctuations and decreases. The temperature response at different temperatures and the calculated Seebeck coefficients are shown below. Figure 4 As shown, the Seebeck coefficient (Si) of the ion thermal battery assembled using the wide-temperature-range ion thermal battery electrolyte in Example 1 is [missing information]. e It can reach 1.50 mVK -1The electrolyte used in Comparative Example 1 (containing 50 mM I) was used instead. - / I3 - The Seebeck coefficient of the ion thermal battery assembled in an aqueous solution is only 0.56 mV K. -1 .

[0059] (2) The wide-temperature-range ion thermal battery electrolyte in Example 2 was tested: Two platinum plates were used as the cold-end electrode and the hot-end electrode, respectively. The hot-end electrode was heated to different temperatures on a heating plate, while the cold-end electrode was maintained at room temperature. Using the wide-temperature-range ion thermal battery electrolyte prepared in Example 2, an ion thermal battery was assembled for electrochemical performance testing. The temperature response at different temperatures and the calculated Seebeck coefficient results are as follows: Figure 5 As shown, under the same test conditions, the Seebeck coefficient of a wide-temperature-range ion thermal battery can reach 1.10 mV K. -1 Similar to the results in Example 1, it still significantly outperforms the ion thermal battery electrolyte (containing 50 mM I) in Comparative Example 1. - / I3 - Excellent electrochemical performance (in aqueous solution).

[0060] (3) The wide-temperature-range ion thermal battery electrolyte in Example 2 was tested: Two platinum plates were used as the cold-end electrode and the hot-end electrode, respectively. The hot-end electrode was heated to different temperatures on a heating plate, while the cold-end electrode was maintained at room temperature. Using the wide-temperature-range ion thermal battery electrolyte prepared in Example 3, an ion thermal battery was assembled and its electrochemical performance was tested. The temperature response at different temperatures and the calculated Seebeck coefficients are shown in the figure below. Figure 6 As shown, under the same test conditions, the Seebeck coefficient of the wide-temperature-range ion thermal battery can reach 1.37 mV K. -1 Similar to the results in Example 1, it still significantly outperforms the ion thermal battery electrolyte (containing 50 mM I) in Comparative Example 1. - / I3 - Excellent electrochemical performance (in aqueous solution).

[0061] (4) The wide-temperature-range ion thermal battery electrolyte in Example 4 was tested: Two platinum sheets were used as the cold-end electrode and the hot-end electrode, respectively. The hot-end electrode was heated to different temperatures on a heating plate, while the cold-end electrode was maintained at room temperature. Using the platinum sheets as electrodes, and the wide-temperature-range ion-thermal battery electrolyte prepared in Example 4, an ion-thermal battery was assembled for electrochemical performance testing. The results are as follows: Figure 7 As shown, under the same test conditions, the Seebeck coefficient of the ion thermal battery is 0.74 mV K. -1It has a superior electrolyte for ion-thermal batteries compared to that in Comparative Example 1 (containing 50 mM I - / I3 - The electrochemical performance of the aqueous solution was compared. However, the Seebeck coefficient decreased significantly compared to Examples 1 to 3. This is because when the concentration of trimethyl sulfoxide added was only 0.05 M (in an aqueous solution containing I), the Seebeck coefficient was significantly lower. - and I3 - When added to an aqueous solution (at a concentration of 1,000 mg / mL), it is related to I3. - The amount of thermosensitive flocculent precipitate generated by the reaction is too small to form an effective three-dimensional network structure in the electrolyte. This leads to the rapid depletion of the precipitate during heating, which is insufficient to suppress the thermal motion of hot-end ions and concentration polarization. At the same time, the low solid content fails to provide enough I3. - The slow-release kinetics maintain the concentration gradient at high temperatures, causing the hot-end chemical potential to decay prematurely. As a result, the Seebeck coefficient increases only slightly. This also underscores the necessity of setting the concentration of the organic sulfoxide salt in the range of 0.05 M to 0.5 M, and preferably 0.2 M, to construct a sufficient and controllable thermosensitive precipitate phase.

[0062] (5) The wide-temperature-range ion thermal battery electrolyte in Example 5 was tested: Two platinum sheets were used as the cold-end electrode and the hot-end electrode, respectively. The hot-end electrode was heated to different temperatures on a heating plate, while the cold-end electrode was maintained at room temperature. Using the platinum sheets as electrodes, and the wide-temperature-range iodine-based ion thermal battery electrolyte prepared in Example 5, an ion thermal battery was assembled and its electrochemical performance was tested. The results are as follows: Figure 8 As shown, under the same test conditions, the Seebeck coefficient of the ion thermal battery can reach 1.10 mV K. -1 Similar to the results in Example 1, it still significantly outperforms the ion thermal battery electrolyte (containing 50 mM I) in Comparative Example 1. - / I3 - Excellent electrochemical performance (in aqueous solution).

[0063] In summary, this invention provides a wide-temperature-range ion thermal battery electrolyte, its preparation method, and the ion thermal battery itself.

[0064] This invention introduces an organic sulfoxide salt into the electrolyte, and the organic sulfoxide salt reacts with I3 - Through ion association reaction, an organic complex flocculent precipitate with thermosensitive properties (thermally controlled dissolution characteristics) is formed in situ. Based on the thermosensitive precipitation phase change regulation mechanism, the flocculent precipitate can suppress thermal convection while increasing the ion concentration gradient and chemical potential gradient at high temperature, thereby achieving stable output of thermoelectric conversion performance over a wide temperature range. This effectively solves the problems of narrow operating temperature range, thermal voltage decay at high temperature, and limited Seebeck coefficient of existing iodine-based ion thermal batteries.

[0065] Specifically, this flocculent precipitate exhibits significantly differentiated thermodynamic behavior: unlike the explosive dissolution of conventional crystals below 60°C, the flocculent precipitate of this invention maintains a slow and controllable decomposition and release kinetics (i.e., a kinetic mechanism of partially undissolved and slow, gradual decomposition) even at hot-end temperatures as high as 85°C. This unique and controllable dissolution kinetic behavior allows the flocculent precipitate to continuously release I3 into the hot-end liquid phase, much like an ion-releasing capsule. - The ions dynamically maintain the reactant concentration gradient and chemical potential gradient at the hot and cold ends at the microscopic level, suppressing the voltage decay caused by the thermal motion of ions at the hot end and solving the fundamental problem of chemical potential decay at high temperatures. Simultaneously, the physical network structure of the flocculent precipitate (i.e., a three-dimensional network structure) allows the flocculent precipitate to act as a pinning agent in the liquid phase, effectively suppressing natural thermal convection and concentration polarization under a strong temperature difference field (85℃ hot end vs. 10℃ cold end), ensuring the stability of the temperature interface and improving the Seebeck coefficient. This invention breaks through the bottleneck of high-temperature chemical potential decay in traditional iodine-based systems at the microscopic level, providing a thermodynamic driving force for a significant increase in the Seebeck coefficient.

[0066] The ion thermal battery assembled with the wide-temperature-range ion thermal battery electrolyte prepared by the method provided in this invention did not exhibit voltage saturation or degradation under extreme temperature difference conditions of 10°C at the cold end and as high as 85°C at the hot end. Instead, it showed a continuous performance growth trend, with a Seebeck coefficient reaching 1.50 mV K. -1 .

[0067] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A method for preparing a wide-temperature-range ion-thermal battery electrolyte, characterized in that, Includes the following steps: Provide an aqueous solution containing an iodine-based redox couple; the iodine-based redox couple is composed of I - and I3 - constitute; Organic sulfoxide salts are added to the aqueous solution of the iodine-containing redox couple, and stirred until flocculent precipitate forms in situ, thus obtaining the wide-temperature-range ion thermal battery electrolyte.

2. The method for preparing the wide-temperature-range ion thermal battery electrolyte according to claim 1, characterized in that, Add 0.05–0.5 mol of an organic sulfoxide salt to each liter of aqueous solution containing an iodine-based redox couple.

3. The method for preparing the wide-temperature-range ion thermal battery electrolyte according to claim 1, characterized in that, Add 0.2 mol of organic sulfoxide salt to each liter of aqueous solution containing an iodine-based redox couple.

4. The method for preparing the wide-temperature-range ion thermal battery electrolyte according to claim 1, characterized in that, The organic sulfoxide salt includes at least one of trimethyl sulfoxide, trimethyl sulfoxide bromide, and trimethyl sulfoxide iodide.

5. The method for preparing the wide-temperature-range ion thermal battery electrolyte according to claim 1, characterized in that, The method for preparing the aqueous solution containing the iodine-containing redox couple includes the following steps: A soluble alkali metal iodide and elemental iodine are added to water and dissolved to obtain an aqueous solution of the iodine-containing redox couple.

6. The method for preparing the wide-temperature-range ion thermal battery electrolyte according to claim 5, characterized in that, The soluble alkali metal iodides include at least one of potassium iodide and sodium iodide.

7. The method for preparing the wide-temperature-range ion thermal battery electrolyte according to claim 1, characterized in that, In the aqueous solution of the iodine-containing redox couple, the I - The concentration of I3 is 10 mmol / L to 500 mmol / L. - The concentration ranges from 10 mmol / L to 500 mmol / L.

8. A wide-temperature-range ion-thermal battery electrolyte, characterized in that, It is prepared by the preparation method according to any one of claims 1-7.

9. An ion thermal battery, the ion thermal battery comprising a cold-end electrode and a hot-end electrode, and an electrolyte located between the cold-end electrode and the hot-end electrode, characterized in that, The electrolyte includes the wide-temperature-range ion thermal battery electrolyte as described in claim 8.

10. The ion thermal battery according to claim 9, characterized in that, The cold end electrode and the hot end electrode are made of the same material.

Images