Ionic redox couple electric cement-based composite material and preparation method thereof

Abstract

The invention relates to an ionic redox couple thermoelectric cement-based composite material, the composite material comprises a cement matrix and redox couples, and the redox couples exist in pores of the cement matrix; wherein the redox pairs are K4 [Fe (CN) 6] and K3 [Fe (CN) 6], and the porosity of the cement matrix is 25%-50%. According to the invention, the migration of ions in a cement matrix is regulated and controlled by introducing the redox couple, so that a relatively high Seebeck coefficient, conductivity and power factor are achieved while good mechanical properties are maintained, and the thermoelectric conversion efficiency is remarkably improved. Besides, the composite material can drive electrode reaction through temperature difference to generate a closed current loop, stable current output is achieved, and the problem of current output of a traditional ionic thermoelectric material is solved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of cement-based thermoelectric composite materials, and relates to an ionic redox pair thermoelectric cement-based composite material and a preparation method thereof. BACKGROUND

[0002] In recent years, with the increasingly serious global energy crisis and climate change, the development of new building materials with high efficiency, energy saving and environmental protection has become a hot spot. Traditional cement concrete has a high thermal conductivity, which will cause a large amount of heat loss during use, thereby intensifying the urban heat island effect. Therefore, how to utilize the characteristics of cement-based materials to realize heat energy recovery and conversion has become an important measure to improve the energy utilization efficiency of buildings. Thermoelectric conversion technology is a reliable method for directly converting heat energy into electrical energy, and has been widely used in industrial waste heat recovery, automobile exhaust recovery and other fields. Introducing the thermoelectric conversion principle into cement-based composite materials can not only improve the energy utilization efficiency of buildings, but also promote the development of cement-based materials towards functionalization and intelligentization. Therefore, cement-based thermoelectric composite materials have become a hot spot of common concern in the academic and industrial circles at home and abroad.

[0003] CN119038947A discloses a sustainable discharging magnesium phosphate cement thermoelectric material and a preparation method and application thereof. The material is composed of magnesium oxide, phosphate, borax, superconducting carbon black and water, and is prepared by mixing, stirring, standing and demolding, and has excellent thermoelectric performance, which can realize continuous and uninterrupted external discharge. The material can improve the voltage by series connection or improve the discharge power by parallel connection.

[0004] CN116102310A discloses a cement-based thermoelectric material and a preparation method thereof. The preparation method is to mix cement, foam stabilizer, foaming agent and water to prepare a cement matrix, and the cement matrix has a high porosity, then the cement matrix is soaked in a sodium chloride solution for vacuum saturation, and the soaking is continued until the pH value of the solution in the pores is lower than 13. This process can increase the ion concentration in the pores of the cement matrix and reduce the OH - concentration, so that the thermoelectric material exhibits a metal cation dominated thermoelectric effect.

[0005] Currently available methods for modifying cement-based thermoelectric materials still have many limitations. On the one hand, commonly used electronic thermoelectric fillers, such as superconducting carbon black, carbon nanotubes, and graphene, while significantly improving the thermoelectric properties of the materials, affect the material strength, and their high preparation costs limit their application and promotion. Furthermore, the hydrophobic nature of superconducting carbon black may make it difficult for gel materials to bind effectively. On the other hand, for ionic thermoelectric materials, which utilize the ion conduction of the cement matrix itself to achieve the thermoelectric effect, the inability of charge carriers to enter the external circuit prevents the formation of a closed current loop, making it difficult to achieve stable current output and limiting their application prospects. In addition, chloride ions readily corrode steel bars, thus affecting the lifespan of reinforced concrete materials. Summary of the Invention

[0006] Problem to be solved by the invention

[0007] This invention aims to provide an ionic redox pair thermoelectric cement-based composite material and its preparation method. The cement-based composite material, by introducing redox pairs to regulate the migration of ions in the cement matrix, can form a closed current loop and achieve stable current output. While maintaining good mechanical properties, it can significantly improve the thermoelectric conversion efficiency.

[0008] Solution for solving the problem

[0009] [1] An ionic redox pair thermoelectric cement-based composite material, wherein the composite material comprises a cement matrix and a redox pair, the redox pair being present in the pores of the cement matrix;

[0010] The redox pair is K4[Fe(CN)6] and K3[Fe(CN)6], and the porosity of the cement matrix is ​​25%-50%.

[0011] [2] According to the ionic redox thermoelectric cement-based composite material described in [1], wherein the connectivity of the cement matrix is ​​20%-60%.

[0012] [3] The ionic redox thermoelectric cement-based composite material according to [1] or [2], wherein the composite material satisfies at least one of the following conditions:

[0013] The closed current loop formed by the composite material has a thermal current of -2 to -5 μA;

[0014] The Seebeck coefficient of the composite material is -0.3 to -0.8 mV / K;

[0015] The electrical conductivity of the composite material is 0.4 to 1.2 S / m;

[0016] The power factor of the composite material is 0.04 to 0.5 μW·m. -1 ·K -2 .

[0017] [4] The ionic redox thermoelectric cement-based composite material according to [1] or [2], wherein the molar ratio of K4[Fe(CN)6] and K3[Fe(CN)6] is 0.5:1-1.5:1.

[0018] [5] A method for preparing a composite material according to any one of [1]-[4], wherein the preparation method comprises the following steps:

[0019] 1) Mix cement, water, and foaming agent to form a cement matrix;

[0020] 2) The cement matrix is ​​immersed in a redox reaction solution and saturated under vacuum to obtain the composite material.

[0021] [6] According to the preparation method described in [5], the mass ratio of the cement, water and foaming agent is 100:(25-50):(2-4).

[0022] [7] The preparation method according to [5] or [6], wherein the foaming agent is a hydrogen peroxide aqueous solution with a mass concentration of 20%-35%.

[0023] [8] According to the preparation method described in [5] or [6], the vacuum saturation time is 3-6 h and the vacuum degree of the vacuum saturation is -0.05 to -0.2 MPa.

[0024] [9] According to the preparation method described in [5] or [6], wherein the concentration of K4[Fe(CN)6] in the redox pair solution is 0.2-0.6 mol / L and the concentration of K3[Fe(CN)6] is 0.2-0.6 mol / L.

[0025]

[10] The preparation method according to [5] or [6], wherein the water-cement ratio is 0.3-0.5.

[0026] Effects of the invention

[0027] The ionic redox-pair thermoelectric cement-based composite material of this invention regulates the migration of ions in the cement matrix by introducing redox pairs, achieving a significant improvement in thermoelectric conversion efficiency while maintaining good mechanical properties. The redox-pair filler of this invention is stable and has no significant corrosive effect on common building materials such as concrete and reinforcing steel.

[0028] The ionic redox-pair thermoelectric cement-based composite material of this invention optimizes the pore structure and improves ion migration efficiency. This ionic redox-pair thermoelectric cement-based composite material exhibits high Seebeck coefficient, electrical conductivity, and power factor. The redox-pair filler of this invention is low-cost, significantly reducing costs compared to carbon materials. This ionic redox-pair thermoelectric cement-based composite material can generate a closed current loop through temperature difference-driven electrode reaction, achieving stable current output and overcoming the current output challenge of traditional ionic thermoelectric materials.

[0029] The ionic redox pair filler of the present invention is beneficial to material forming. The redox pair solution is injected into the pores of cement-based materials under vacuum conditions without affecting the setting process of the cement matrix. Moreover, the filler is evenly distributed and has less loss. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the test device for Seebeck coefficient and thermocurrent in this invention. Detailed Implementation

[0031] Various exemplary embodiments, features, and aspects of the present invention will be described in detail below. The term "exemplary" as used herein means "serving as an example, embodiment, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as superior to or better than other embodiments.

[0032] Furthermore, to better illustrate the present invention, numerous specific details are set forth in the following detailed embodiments. Those skilled in the art should understand that the present invention can be practiced without certain specific details. In other instances, methods, means, apparatus, and steps well known to those skilled in the art have not been described in detail in order to highlight the spirit of the present invention.

[0033] Unless otherwise stated, all units used in this specification are international standard units, and all numerical values ​​and ranges appearing in this invention should be understood to include systematic errors that are unavoidable in industrial production.

[0034] In this specification, the word "may" has two meanings: to perform a certain process and not to perform a certain process.

[0035] In this specification, references to "some specific / preferred embodiments," "other specific / preferred embodiments," "implementation," etc., refer to specific elements (e.g., features, structures, properties, and / or characteristics) related to that embodiment, which are included in at least one of the embodiments described herein and may or may not be present in other embodiments. Furthermore, it should be understood that these elements may be combined in any suitable manner in various embodiments.

[0036] In this specification, the range of values ​​referred to as “value A - value B” or “value A to value B” refers to the range that includes the endpoints value A and value B.

[0037] In this instruction manual, when "room temperature" or "room temperature" is used, the temperature can be 15℃ to 30℃, or more specifically 15℃ to 25℃, such as 20℃.

[0038] In this invention, the hydrogen peroxide used is an aqueous solution of hydrogen peroxide, and the concentration of hydrogen peroxide mentioned refers to the mass concentration of hydrogen peroxide.

[0039] In this invention, the connectivity rate of the cement matrix refers to the proportion of interconnected holes in the cement matrix.

[0040] This invention proposes a novel thermoelectric conversion system for cement-based composite materials. By introducing redox pairs to regulate ion migration in the cement matrix, a significant improvement in thermoelectric conversion efficiency is achieved while maintaining good mechanical properties. This technology represents a systematic innovation in material design, preparation process, and performance testing, providing an effective technical path to address the bottlenecks in the application of cement-based materials in energy conservation and environmental protection. It has significant practical implications and broad application prospects for improving building energy conservation and emission reduction, and promoting sustainable urban development.

[0041] Ionic redox couples for thermoelectric cementitious composites

[0042] First, this invention provides an ionic redox-paired thermoelectric cement-based composite material. By regulating ion migration through redox pairs, the thermoelectric conversion efficiency is significantly improved. At the same time, a closed current loop is generated by driving electrode reactions through temperature difference, achieving stable current output and overcoming the current output problem of ionic materials.

[0043] Specifically, the ionic redox pair thermoelectric cement-based composite material provided by the present invention comprises a cement matrix and a redox pair, wherein the redox pair exists within the pores of the cement matrix;

[0044] The redox pair is K4[Fe(CN)6] and K3[Fe(CN)6], and the porosity of the cement matrix is ​​25%-50%.

[0045] In some embodiments, the redox pairs of the present invention need to be prepared as solutions for use. Therefore, the redox pairs of the present invention are soluble in water. For example, the redox pairs K4[Fe(CN)6] and K3[Fe(CN)6] can be prepared as solutions for use.

[0046] In some embodiments, the redox pairs in the composite material are present in solution form.

[0047] In some embodiments, the molar ratio of K4[Fe(CN)6] to K3[Fe(CN)6] is 0.5:1 to 1.5:1, for example, 0.6:1, 0.8:1, 1:1, 1.2:1, or 1.4:1. In some preferred embodiments, the molar ratio of K4[Fe(CN)6] to K3[Fe(CN)6] is 0.8:1 to 1.2:1.

[0048] In some embodiments, the cement in the cement matrix is ​​silicate cement.

[0049] In some embodiments, the cement in the cement matrix has a strength grade of 42.5 or 52.5.

[0050] In some embodiments, the porosity of the cement matrix is ​​27%-45%, for example 27%, 30%, 32%, 35%, 40% or 45%.

[0051] In some embodiments, the connectivity of the cementitious matrix is ​​20%-60%, for example 22%, 25%, 28%, 30%, 35%, 40%, 45%, 50%, or 58%.

[0052] In this invention, the porosity and connectivity of the cement matrix are optimized, which significantly improves the ion migration efficiency of the final ionic redox thermoelectric cement-based composite material, thereby improving the thermoelectric conversion efficiency of the thermoelectric cement-based composite material.

[0053] In this invention, by preparing cement mortar / concrete specimens filled with the above-mentioned ionic redox thermoelectric cement-based composite material, the above-mentioned ionic redox thermoelectric cement-based composite material forms a closed current loop and has a stable current output.

[0054] In some embodiments, the closed current loop formed by the composite material has a thermocurrent of -2 to -5 μA, such as -2.2 μA, -2.5 μA, -3 μA, -3.5 μA, -4 μA or -4.5 μA.

[0055] In some embodiments, the Seebeck coefficient of the composite material is -0.3 to -0.8 mV / K, for example -0.35 mV / K, -0.4 mV / K, -0.45 mV / K, -0.5 mV / K, -0.55 mV / K, -0.6 mV / K, -0.65 mV / K, or -0.7 mV / K.

[0056] In some embodiments, the electrical conductivity of the composite material is from 0.4 to 1.2 S / m, for example 0.45 S / m, 0.5 S / m, 0.55 S / m, 0.6 S / m, 0.7 S / m, 0.8 S / m, 0.9 S / m, 0.95 S / m, 1 S / m or 1.1 S / m.

[0057] In some embodiments, the power factor of the composite material is 0.04 to 0.5 μW·m. -1 ·K -2 For example, 0.045 μW·m -1 ·K -2 0.05 μW·m -1 ·K -2 0.06 μW·m -1 ·K -2 0.08 μW·m -1 ·K -2 0.1 μW·m -1 ·K -2 0.15 μW·m -1 ·K -2 0.2 μW·m -1 ·K -2 0.3 μW·m -1 ·K -2 or 0.4 μW·m -1 ·K -2 .

[0058] Method for preparing ionic redox couples for thermoelectric cementitious composites

[0059] This invention provides a method for preparing the above-mentioned ionic redox thermoelectric cement-based composite material, which includes the following steps:

[0060] 1) Mix cement, water, and foaming agent to form a cement matrix;

[0061] 2) The cement matrix is ​​immersed in a redox reaction solution and saturated under vacuum to obtain the composite material.

[0062] In some implementations, the mass ratio of cement to water is 100:(25-50), for example 100:27, 100:30, 100:35, 100:40 or 100:45.

[0063] In some embodiments, the mass ratio of the cement to the foaming agent is 100:(2-4), for example 100:3.

[0064] In some embodiments, the mass ratio of the cement, water and foaming agent is 100:(25-50):(2-4), for example 100:27:3, 100:30:3, 100:35:3, 100:40:3 or 100:45:3.

[0065] In some embodiments, the water-cement ratio of the cementitious matrix is ​​0.3-0.5, for example 0.3, 0.4 or 0.5.

[0066] In this invention, the water-cement ratio refers to the mass ratio of the water phase to the cement in the cement matrix. The water phase includes water and other water phase components, such as foaming agents in liquid form.

[0067] In some embodiments, the foaming agent can be a physical foaming agent or a chemical foaming agent. The physical foaming agent generates gas through physical means, such as volatilization, expansion, or sublimation, forming a porous structure. The physical foaming agent can be dry ice, compressed nitrogen, Freon, or ethanol, etc. The chemical foaming agent generates gas, such as oxygen, carbon dioxide, or nitrogen, through thermal decomposition or chemical reaction, forming a porous structure. The chemical foaming agent can be hydrogen peroxide, sodium bicarbonate, or ammonium carbonate, etc.

[0068] In some embodiments, the foaming agent is an aqueous solution of hydrogen peroxide with a mass concentration of 20%-35%, such as an aqueous solution of hydrogen peroxide with a mass concentration of 25% or 30%.

[0069] The preparation method of the present invention can control the porosity and connectivity of the cement matrix by adjusting the ratio of water and foaming agent, thereby achieving synergistic optimization of the pore structure and improving ion migration efficiency.

[0070] In some implementations, cement, water, and foaming agent are mixed and molded, and then cured for more than 28 days to form the cement matrix.

[0071] In some specific implementations, the maintenance period is 28-40 days, such as 30 or 35 days.

[0072] In some specific implementations, the maintenance is described as sealed maintenance.

[0073] In some specific implementations, the curing temperature is 10-30°C, for example 15°C, 20°C or 25°C.

[0074] In some specific implementations, the maintenance is either dry maintenance or wet maintenance.

[0075] In some specific implementations, the humidity of the maintenance is greater than 95% RH, such as 96% RH or 98% RH.

[0076] In some embodiments, the concentration of K4[Fe(CN)6] in the solution is 0.2-0.6 mol / L, for example 0.25 mol / L, 0.3 mol / L, 0.4 mol / L or 0.5 mol / L.

[0077] In some embodiments, the concentration of K3[Fe(CN)6] in the solution is 0.2-0.6 mol / L, for example 0.25 mol / L, 0.3 mol / L, 0.4 mol / L or 0.5 mol / L.

[0078] In some embodiments, the redox pair has the same concentration of K4[Fe(CN)6] and K3[Fe(CN)6] in the solution.

[0079] In some embodiments, the concentrations of K4[Fe(CN)6] and K3[Fe(CN)6] in the solution are both 0.2-0.6 mol / L, for example 0.25 mol / L, 0.3 mol / L, 0.4 mol / L or 0.5 mol / L.

[0080] In some embodiments, the cement matrix is ​​dried before being immersed in the redox couple solution.

[0081] In some specific implementations, the drying temperature is 60-100°C, for example 70°C, 80°C or 90°C.

[0082] In some specific implementations, the drying time is 12-40 hours, for example 20 hours, 24 hours or 30 hours.

[0083] In some implementations, the vacuum saturation time is 3-6 hours, for example, 4 hours or 5 hours.

[0084] In some embodiments, the vacuum saturation vacuum degree is -0.05 to -0.2 MPa, for example -0.07 MPa, -0.09 MPa, -0.11 MPa or -0.15 MPa.

[0085] In some implementations, the vacuum saturation is performed in a negative pressure vacuum cooker.

[0086] Porosity and connectivity testing method

[0087] The porosity and connectivity in this invention are obtained by CT and mercury porosimetry.

[0088] Seebeck coefficient and thermoelectric current testing method

[0089] To ensure the electrolyte solution in the pore solution of the cement-based material is in constant thermodynamic equilibrium, the present invention requires a slow and uniform temperature increase during testing. The Seebeck coefficient and thermocurrent are measured using a specially designed testing device, as illustrated in the schematic diagram below. Figure 1 As shown. Thermocouples are placed parallel to each other on the upper and lower surfaces of the sample to measure the temperature difference. Copper wires of the thermoelectric specimen are wound around electrodes coated with silver paste. These copper wires and the copper wires of the thermocouples are connected to data loggers (Agilent 34972A and 34901A) to collect the thermoelectric voltage (V) between the two ends of the sample. TE The voltage accuracy of the data logger used in this invention is less than 0.005% of the sum of the reading error and the measurement range of 0.004%. The data logger has high accuracy, and the measured voltage difference can be directly considered as the voltage difference between the upper and lower ends of the specimen. For all measured samples, the cold end is kept at room temperature (approximately 24±2℃), while the hot end is heated to 80℃ at a rate of 0.01K / s by a heater to ensure that the material generates a steady-state voltage signal under the corresponding temperature difference. The heating rate is automatically controlled by a thermostat (Shimaden FP93, Shimaden Co., Ltd). The Seebeck coefficient is calculated as: S = V TE / ΔT, V TE Let be the thermoelectric voltage, and ΔT be the temperature difference across the sample. Six thermoelectric samples were measured to determine the average Seebeck coefficient.

[0090] The thermoelectric current test procedure is similar to the Seebeck test, and similar measurements are performed on thermoelectric specimens. Thermocouples are placed parallel to and in close contact with the upper and lower surfaces of the sample. Copper wires of the thermoelectric specimen are wound around electrodes coated with silver paste. These copper wires and the copper wires of the thermocouples are connected to data loggers (Agilent 34972A and 34901A) to collect the thermoelectric current (IT) between the two ends of the sample. TE The data logger used in this invention has a current accuracy of less than 0.005% of the sum of the reading error and the measurement range of 0.004%. The data logger has high accuracy, and the measured current is directly regarded as the current passing through the upper and lower ends of the specimen.

[0091] Example

[0092] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0093] The raw materials used in the following embodiments are as follows:

[0094] K4[Fe(CN)6]: Produced by Tianjin Huasheng Chemical Reagent Co., Ltd., with analytical grade purity.

[0095] K3[Fe(CN)6]: Produced by Tianjin Juhengda Chemical Co., Ltd., with analytical grade purity.

[0096] Hydrogen peroxide solution: mass concentration of 27.5%, produced by Guangzhou Hengjian Chemical Technology Co., Ltd.

[0097] Silicate cement: strength grade 42.5.

[0098] Example 1

[0099] Weigh silicate cement, water, and a 27.5% hydrogen peroxide solution in a mass ratio of 100:27:3 and set aside for later use; the water-cement ratio (w / c) is 0.3, wherein the 27.5% hydrogen peroxide solution is included in the water.

[0100] Silicate cement, water, and a 27.5% hydrogen peroxide solution were sequentially added to a container and stirred slowly at 60 rpm for 5 minutes using a planetary mixer, followed by rapid stirring at 130 rpm for 10 minutes. Once homogeneous, the mixture was poured into a 20mm × 20mm × 80mm stainless steel mold. The sample surface was then covered with a sealing film to prevent water evaporation, and the sample was placed in an environment with a controlled temperature of 20±2℃. After demolding for 24 hours, the sample was placed in a curing chamber at 20±2℃ and wet-cured for 28 days at a humidity greater than 95% RH to ensure complete hydration and obtain the cementitious matrix.

[0101] The cement matrix was dried in an oven at 80°C for 24 hours, then immersed in a mixed solution of K4[Fe(CN)6] and K3[Fe(CN)6], both with a concentration of 0.25 mol / L. The solution was then placed in a vacuum cooker with a vacuum degree of -0.098 MPa and saturated for 3 hours to fill the pores of the cement matrix with the solution. The mixture was then sealed to obtain an ionic redox thermoelectric cement-based composite material, denoted as Composite Material-I.

[0102] Example 2

[0103] The experimental method was similar to that in Example 1, except that the water-cement ratio was changed from 0.3 to 0.4, and the mass ratio of silicate cement, water, and 27.5% hydrogen peroxide was changed to 100:37:3, resulting in an ionic redox thermoelectric cement-based composite material, denoted as Composite Material-II.

[0104] Example 3

[0105] Similar to the preparation method in Example 1, except that the water-cement ratio was changed from 0.3 to 0.5, and the mass ratio of silicate cement, water, and 27.5% hydrogen peroxide was changed to 100:47:3, to obtain an ionic redox thermoelectric cement-based composite material, denoted as Composite Material-III.

[0106] Comparative Example 1

[0107] The experimental method was similar to that in Example 3, except that the 27.5% hydrogen peroxide solution was replaced with water, i.e. no foaming agent was added, to obtain an ionic redox thermoelectric cement-based composite material, denoted as Composite Material-IV.

[0108] Performance testing

[0109] The porosity and connectivity of the cement matrix in Examples 1-3 and Comparative Example 1 were measured, and the results are shown in Table 1.

[0110] Table 1. Porosity and connectivity of cement matrix in Examples 1-3

[0111] Examples Porosity Connectivity Example 1 28.63％ 24.79％ Example 2 35.24％ 38.91％ Example 3 43.85％ 55.13％ Comparative Example 1 22％ 0

[0112] By preparing cement paste specimens filled with the above-mentioned ionic redox thermoelectric cement-based composite material, the above-mentioned ionic redox thermoelectric cement-based composite material forms a closed current loop with a stable current output. The thermoelectric current of the composite materials obtained in Examples 1-3 and Comparative Example 1 was measured.

[0113] The Seebeck coefficients of the composite materials obtained in Examples 1-3 and Comparative Example 1 were determined, and the conductivity and power factor were calculated according to the following formulas.

[0114] Formula for calculating electrical conductivity:

[0115] σ=l / (s R)

[0116] Power factor calculation formula:

[0117] PF=σ·S 2

[0118] Where σ is the conductivity, l is the specimen length, s is the specimen end area, R is the resistance (313.04Ω in Example 1, 294.86Ω in Example 2, and 167.65Ω in Example 3), and S is the Seebeck coefficient; in the above examples, l is 80mm and s is 400mm. 2 .

[0119] The performance test results of the composite materials obtained in Examples 1-3 and Comparative Example 1 are shown in Table 2 below.

[0120] Table 2 Performance test results of composite materials

[0121]

[0122]

[0123] As shown in Table 2, the composite material of the present invention can generate a high thermocurrent, while also possessing a high Seebeck coefficient, electrical conductivity, and power factor. The composite material in Comparative Example 1 did not generate a thermocurrent.

[0124] It should be noted that although the technical solution of the present invention has been described with specific examples, those skilled in the art will understand that the present invention should not be limited thereto.

[0125] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or technical improvements to the embodiments in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. An ionic redox thermoelectric cement-based composite material, characterized in that, The composite material comprises a cement matrix and redox pairs, wherein the redox pairs exist within the pores of the cement matrix; The redox pair is K4[Fe(CN)6] and K3[Fe(CN)6], and the porosity of the cement matrix is ​​25%-50%.

2. The ionic redox thermoelectric cement-based composite material according to claim 1, characterized in that, The connectivity of the cementitious matrix is ​​20%-60%.

3. The ionic redox thermoelectric cement-based composite material according to claim 1 or 2, characterized in that, The composite material satisfies at least one of the following conditions: The closed current loop formed by the composite material has a thermal current of -2 to -5 μA; The Seebeck coefficient of the composite material is -0.3 to -0.8 mV / K; The electrical conductivity of the composite material is 0.4 to 1.2 S / m; The power factor of the composite material is 0.04 to 0.5 μW·m. -1 ·K -2 .

4. The ionic redox thermoelectric cement-based composite material according to claim 1 or 2, characterized in that, The molar ratio of K4[Fe(CN)6] to K3[Fe(CN)6] is 0.5:1 to 1.5:

1.

5. A method for preparing a composite material according to any one of claims 1-4, characterized in that, The preparation method includes the following steps: 1) Mix cement, water, and foaming agent to form a cement matrix; 2) The cement matrix is ​​immersed in a redox reaction solution and saturated under vacuum to obtain the composite material.

6. The preparation method according to claim 5, characterized in that, The mass ratio of the cement, water and foaming agent is 100:(25-50):(2-4).

7. The preparation method according to claim 5 or 6, characterized in that, The foaming agent is a hydrogen peroxide aqueous solution with a mass concentration of 20%-35%.

8. The preparation method according to claim 5 or 6, characterized in that, The vacuum saturation time is 3-6 hours, and the vacuum degree of the vacuum saturation is -0.05 to -0.2 MPa.

9. The preparation method according to claim 5 or 6, characterized in that, In the redox pair solution, the concentration of K4[Fe(CN)6] is 0.2-0.6 mol / L and the concentration of K3[Fe(CN)6] is 0.2-0.6 mol / L.

10. The preparation method according to claim 5 or 6, characterized in that, The water-cement ratio is 0.3-0.5.

Images