Method for regulating and controlling pore structure of cement-based supercapacitor

Abstract

The invention discloses a method for regulating and controlling a pore structure of a cement-based supercapacitor, and belongs to the technical field of energy storage. The method for regulating and controlling the pore structure of the cement-based supercapacitor comprises the following steps: firstly, preparing foam, then uniformly stirring cement and sand, adding water and a water reducing agent, fully stirring, and finally, doping the foam into slurry, and fully stirring to obtain the slurry. And pouring the stirred slurry into a mold, standing for 24 hours, and demolding to obtain the cement matrix. And packaging the front, back, left and right surfaces of the cement matrix by using epoxy resin, and drying at 60 DEG C for 3 days. And soaking the treated test piece in a 2mol / L KOH solution for 5 days, and then manufacturing the test piece into the cement-based supercapacitor. According to the invention, the regulation and control of the pore structure of the cement-based supercapacitor are realized, the treated cement-based supercapacitor has better pore connectivity, the pores show tropism, the conductivity and the capacitance are better, the specific capacitance can reach 63.3 F / m < 2 > to the maximum, and the compressive strength and the breaking strength are reduced.

Description

Technical Field

[0001] This invention belongs to the field of energy storage technology, specifically relating to a method for regulating the pore structure of cement-based supercapacitors. Background Technology

[0002] In traditional energy storage methods, pumped hydro storage has high terrain requirements and high costs, compressed air energy storage systems are complex and difficult to apply on a large scale, flywheel energy storage has high requirements for material strength and durability, and batteries have drawbacks such as high safety risks and short lifespan. Therefore, it is urgent to develop new energy storage technologies with low requirements, low cost, high safety, and long lifespan. Cement-based supercapacitors possess these properties and the potential for large-scale energy storage.

[0003] Cement-based materials are widely used and inexpensive. Furthermore, the interior of cement-based materials is filled with pores and ionic solutions. The interconnected pores provide channels for ion transport, and the ionic solutions can serve as electrolytes. Therefore, cement-based materials have the potential to be used to fabricate supercapacitors, which can both store electrical energy and bear loads as a structural component. However, research on cement-based supercapacitors is still incomplete, and many aspects remain unexplored. Therefore, further research on cement-based supercapacitors is urgently needed.

[0004] The key to improving the energy storage performance of cement-based supercapacitors lies in the regulation of the pore structure of cement-based materials. However, research on the regulation of the pore structure of cement-based supercapacitors is currently very scarce. Therefore, it is imperative to carry out research on regulating the pore structure. Summary of the Invention

[0005] To address the shortcomings of the prior art, this invention provides a method for controlling the pore structure of cement-based supercapacitors.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for controlling the pore structure of cement-based supercapacitors includes the following steps: (1) Sodium dodecyl sulfate, sodium carboxymethyl cellulose and water are mixed to obtain foam; the present invention uses sodium dodecyl sulfate and sodium carboxymethyl cellulose in combination, which can promote the formation of foam and maintain the durability of foam.

[0007] (2) Mix cement and sand evenly, then add water and water-reducing agent and stir to obtain cement paste. Then add the foam prepared in step (1) and stir evenly. Pour into mold, let stand and then demold to obtain cement matrix.

[0008] (3) After encapsulating and curing a portion of the cement matrix with epoxy resin, heat it, then remove the encapsulating material from the heated cement matrix, and then immerse the cement matrix in potassium hydroxide solution to obtain the immersed cement matrix. The present invention can partially encapsulate the cement matrix to regulate the internal pore structure of the cement matrix and achieve a directional pore structure. However, if the cement matrix is ​​completely encapsulated and cured and then heated, the pores inside the cement matrix will not be able to form a directional pore structure, resulting in poor conductivity.

[0009] (4) Use epoxy resin to encapsulate the four sides of the cement substrate after soaking, and then cure it. Apply graphite conductive adhesive to the upper and lower surfaces of the cured cement substrate, insert a copper wire into the graphite conductive adhesive, then cover the copper sheet on the graphite conductive adhesive, and finally seal the upper and lower surfaces with epoxy resin to obtain a cement-based supercapacitor.

[0010] In a preferred embodiment of the present invention, the mass ratio of sodium dodecyl sulfate, sodium carboxymethyl cellulose and water is (1~20):(1~10):1000.

[0011] As a preferred embodiment of the present invention, the mass ratio of cement, sand, water, water-reducing agent and foam is 1000:(1500~2000):(300~400):(1~4):(60~100).

[0012] As a preferred embodiment of the present invention, the cement is one of silicate cement, slag silicate cement, pozzolanic silicate cement, fly ash silicate cement, composite silicate cement, rapid-hardening silicate cement, aluminate cement or sulfoaluminate cement.

[0013] In a preferred embodiment of the present invention, the sand is Chinese ISO standard sand with a particle size of 0.08-2.0 mm; the water-reducing agent is PCA-I polycarboxylate high-performance water-reducing agent.

[0014] As a preferred embodiment of the present invention, the cement matrix is ​​a quadrangular prism; in step (3), the four surfaces of the cement matrix are encapsulated and cured with epoxy resin.

[0015] In a preferred embodiment of the present invention, in step (3), the heating temperature is 60°C and the heating time is 3 days.

[0016] In a preferred embodiment of the present invention, the concentration of the potassium hydroxide solution is 2 mol / L; the soaking time is 5 days.

[0017] Compared with existing technologies, the beneficial effects of this invention are as follows: The method for regulating the pore structure of cement-based supercapacitors described in this invention can not only improve pore connectivity and pore orientation, but also greatly enhance energy storage capacity, providing a new route for innovation in cement-based supercapacitor energy storage technology. Furthermore, the cement-based supercapacitors prepared by this invention are low in cost, simple in structure, durable, stable, and highly safe. Attached Figure Description

[0018] Figure 1 This is a flowchart illustrating the manufacturing process of the cement-based supercapacitor of this invention.

[0019] Figure 2 This is a porosity diagram of the cement matrix of the cement-based supercapacitors prepared in Embodiment 1 and Comparative Examples 1-2 of the present invention.

[0020] Figure 3 These are relative deviation diagrams of the throat area and the number of throats in the cement-based supercapacitors prepared in Embodiment 1 and Comparative Examples 1-2 of the present invention; wherein, (a) is a relative deviation diagram of the throat area and (b) is a relative deviation diagram of the number of throats.

[0021] Figure 4 These are AC impedance diagrams of the cement-based supercapacitors prepared in Example 1 and Comparative Examples 1-2 of the present invention; wherein, (a) is Comparative Example 1, and (b) is Comparative Example 2 and Example 1.

[0022] Figure 5 This is a cyclic voltammetry test curve of the cement-based supercapacitor in Comparative Example 1 of this invention.

[0023] Figure 6 This is a cyclic voltammetry test curve of the cement-based supercapacitor in Comparative Example 2 of this invention.

[0024] Figure 7 This is a cyclic voltammetry test curve of the cement-based supercapacitor in Embodiment 1 of the present invention.

[0025] Figure 8 This is a specific capacitance diagram of the cement-based supercapacitors prepared in Example 1 and Comparative Examples 1-2 of the present invention.

[0026] Figure 9 These are diagrams illustrating the charging and discharging process of the cement-based supercapacitor described in this invention. (a) shows the charging process of the cement-based supercapacitor, and (b) shows the discharging process of the cement-based supercapacitor. Detailed Implementation

[0027] To better illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0028] Example 1 A method for controlling the pore structure of cement-based supercapacitors by inducing heating tropism specifically includes the following steps: Step 1: Using sodium dodecyl sulfate, sodium carboxymethyl cellulose, and laboratory water as raw materials, the raw materials are mixed in a mass ratio of sodium dodecyl sulfate, sodium carboxymethyl cellulose, and water of 3:1:1000 to prepare foam that meets the requirements for improving the porosity of cement matrix.

[0029] Step 2: Using cement, sand, laboratory water, water-reducing agent, and foam as raw materials, the cement is P·O 42.5 ordinary Portland cement, the sand is Chinese ISO standard sand with a particle size of 0.08-2.0mm, and the water-reducing agent is PCA-I polycarboxylate high-performance water-reducing agent. The mass ratio of each raw material and foam is 1000:1800:350:2.2:83. First, mix the weighed cement and standard sand evenly, then add laboratory water and water-reducing agent in sequence and stir evenly to prepare cement slurry. Then, add the foam in a measured amount to the cement slurry, stir evenly, pour into a 30*30*30mm mold, let it stand for 24 hours, and then demold to prepare the cement matrix.

[0030] Step 3: The pore structure of the prepared cement matrix is ​​regulated by heat-induced orientation. This involves encapsulating the four sides of the cement matrix with epoxy resin and then drying it at 60°C for 3 days in an electrically heated constant-temperature drying oven. The epoxy resin used is a UV-cured resin, extruded onto the surface of the cement matrix and cured by ultraviolet light. 20g is used on each side, ensuring complete encapsulation of all four sides to prepare a cement matrix that meets the requirements for pore connectivity and orientation.

[0031] Step 4: Use a small shovel to remove the epoxy resin from the cement matrix obtained in step 3, and then soak it in a 1000ml beaker filled with 2mol / L KOH solution for 5 days. During soaking, the mouth of the beaker needs to be sealed with plastic wrap to prepare a cement matrix with energy storage capacity.

[0032] Step 5: Encapsulate the impregnated cement substrate with epoxy resin, covering all four sides (front, back, left, and right). The epoxy resin at the edges of the top and bottom surfaces should extend 5mm beyond the surface. Next, apply 5g of graphite conductive adhesive (Osbon A528) to the top and bottom surfaces, ensuring it is in full contact with the cement substrate. Then, insert one end of a 70mm long, 1mm radius copper wire into the graphite conductive adhesive. Next, cover the graphite conductive adhesive with a 0.1mm*30mm*30mm copper sheet, ensuring it is in full contact with the adhesive. The other end of the copper wire should be exposed. Finally, seal the top and bottom surfaces with epoxy resin, ensuring it is in close contact with the other surfaces, completely encapsulating the cement substrate without gaps. This yields a cement-based supercapacitor. Figure 1 As shown.

[0033] Example 2 The only difference between this embodiment and Embodiment 1 is as follows: Step 1: The raw materials are mixed in a mass ratio of sodium dodecyl sulfate, sodium carboxymethyl cellulose, and water of 20:10:1000; Step 2: The mass ratio of cement, sand, water, water-reducing agent, and foam is 1000:1500:300:4:100; Step 3: The drying temperature is 120℃ and the time is 3 days; Step 4: The concentration of potassium hydroxide solution is 1 mol / L and the soaking time is 5 days.

[0034] Example 3 The only difference between this embodiment and Embodiment 1 is as follows: Step 1: The raw materials are mixed in a mass ratio of sodium dodecyl sulfate, sodium carboxymethyl cellulose, and water of 1:1:1000; Step 2: The mass ratio of cement, sand, water, water-reducing agent, and foam is 1000:2000:400:1:60; Step 3: The drying temperature is 100℃ and the time is 7 days; Step 4: The concentration of potassium hydroxide solution is 5 mol / L and the soaking time is 1 day.

[0035] Comparative Example 1 A method for controlling the pore structure of cement-based supercapacitors by inducing heating tropism specifically includes the following steps: Step 1: Using sodium dodecyl sulfate, sodium carboxymethyl cellulose, and laboratory water as raw materials, the raw materials are mixed in a mass ratio of sodium dodecyl sulfate, sodium carboxymethyl cellulose, and water of 3:1:1000 to prepare foam that meets the requirements for improving the porosity of cement matrix.

[0036] Step 2: Using cement, sand, laboratory water, water-reducing agent, and foam as raw materials, the cement is P·O 42.5 ordinary Portland cement, the sand is Chinese ISO standard sand with a particle size of 0.08-2.0mm, and the water-reducing agent is PCA-I polycarboxylate high-performance water-reducing agent. The mass ratio of each raw material and foam is 1000:1800:350:2.2:83. First, mix the weighed cement and standard sand evenly, then add laboratory water and water-reducing agent in sequence and stir evenly to prepare cement slurry. Then, add the foam in a measured amount to the cement slurry, stir evenly, pour into a 30*30*30mm mold, let it stand for 24 hours, and then demold to prepare the cement matrix.

[0037] Step 3: The prepared cement matrix is ​​subjected to 3 days of standard curing. Standard curing is carried out in an environment with a temperature of 20℃ and a humidity of 95%.

[0038] Step 4: Immerse the cured cement matrix in a 1000ml beaker filled with 2mol / L KOH solution for 5 days. During immersion, the mouth of the beaker needs to be sealed with plastic wrap to prepare a cement matrix with energy storage capacity.

[0039] Step 5: Encapsulate the impregnated cement substrate with epoxy resin. During encapsulation, the epoxy resin at the edges of the top and bottom surfaces should extend 5mm beyond the surface. The epoxy resin used is UV-cured crystal glue, extruded onto the cement substrate surface and cured by ultraviolet light. 20g of UV-cured crystal glue is used on each side, completely covering all four sides of the cement substrate. Next, apply 5g of graphite conductive adhesive (Osbon A528) to the top and bottom surfaces, ensuring full contact with the cement substrate surface. Then, insert a 70mm long, 1mm radius copper wire into the graphite conductive adhesive. Next, cover the graphite conductive adhesive with a 0.1mm*30mm*30mm copper sheet, ensuring full contact. Finally, seal the top and bottom surfaces with epoxy resin, ensuring close contact with the epoxy resin on other surfaces, completely encapsulating the cement substrate without gaps. This yields the cement-based supercapacitor.

[0040] Comparative Example 2 A method for controlling the pore structure of cement-based supercapacitors by inducing heating tropism specifically includes the following steps: Step 1: Using sodium dodecyl sulfate, sodium carboxymethyl cellulose, and laboratory water as raw materials, the raw materials are mixed in a mass ratio of sodium dodecyl sulfate, sodium carboxymethyl cellulose, and water of 3:1:1000 to prepare foam that meets the requirements for improving the porosity of cement matrix.

[0041] Step 2: Using cement, sand, laboratory water, water-reducing agent, and foam as raw materials, the cement is P·O 42.5 ordinary Portland cement, the sand is Chinese ISO standard sand with a particle size of 0.08-2.0mm, and the water-reducing agent is PCA-I polycarboxylate high-performance water-reducing agent. The mass ratio of each raw material and foam is 1000:1800:350:2.2:83. First, mix the weighed cement and standard sand evenly, then add laboratory water and water-reducing agent in sequence and stir evenly to prepare cement slurry. Then, add the foam in a measured amount to the cement slurry, stir evenly, pour into a 30*30*30mm mold, let it stand for 24 hours, and then demold to prepare the cement matrix.

[0042] The third step is to regulate the pore structure of the cement matrix by heat treatment. The heat treatment is carried out in an electric constant temperature drying oven at 60°C for 3 days.

[0043] Step 4: Immerse the treated cement matrix in a 1000ml beaker filled with 2mol / L KOH solution for 5 days. During immersion, the mouth of the beaker needs to be sealed with plastic wrap to prepare a cement matrix with energy storage capacity. Step 5: Encapsulate the impregnated cement substrate with epoxy resin. During encapsulation, the epoxy resin at the edges of the top and bottom surfaces should extend 5mm above the surface. The epoxy resin used is UV-cured crystal resin, extruded onto the cement substrate surface and cured by ultraviolet light. Use 20g on each side, completely encapsulating all four sides of the cement substrate. Next, apply 5g of graphite conductive adhesive (Osbon A528) to the top and bottom surfaces, ensuring full contact with the cement substrate surface. Then, insert a 70mm long, 1mm radius copper wire into the graphite conductive adhesive. Next, cover the graphite conductive adhesive with a 0.1mm*30mm*30mm copper sheet, ensuring full contact. Finally, seal the top and bottom surfaces with epoxy resin, ensuring close contact with the epoxy resin on other surfaces, completely encapsulating the cement substrate without gaps. This yields the cement-based supercapacitor.

[0044] Comparative Example 3 A method for controlling the pore structure of cement-based supercapacitors by inducing heating tropism specifically includes the following steps: Step 1: Using sodium carboxymethyl cellulose and laboratory water as raw materials, the raw materials are mixed at a mass ratio of sodium carboxymethyl cellulose to water of 4:1000 to prepare foam that meets the requirements for improving the porosity of cement matrix.

[0045] Step 2: Using cement, sand, laboratory water, water-reducing agent, and foam as raw materials, the cement is P·O 42.5 ordinary Portland cement, the sand is Chinese ISO standard sand with a particle size of 0.08-2.0mm, and the water-reducing agent is PCA-I polycarboxylate high-performance water-reducing agent. The mass ratio of each raw material and foam is 1000:1800:350:2.2:83. First, mix the weighed cement and standard sand evenly, then add laboratory water and water-reducing agent in sequence and stir evenly to prepare cement slurry. Then, add the foam in a measured amount to the cement slurry, stir evenly, pour into a 30*30*30mm mold, let it stand for 24 hours, and then demold to prepare the cement matrix.

[0046] Step 3: The pore structure of the prepared cement matrix is ​​regulated by heat-induced orientation. This involves encapsulating the four sides of the cement matrix with epoxy resin and then drying it at 60°C for 3 days in an electrically heated constant-temperature drying oven. The epoxy resin used is a UV-cured resin, extruded onto the surface of the cement matrix and cured by ultraviolet light. 20g is used on each side, ensuring complete encapsulation of all four sides to prepare a cement matrix that meets the requirements for pore connectivity and orientation.

[0047] Step 4: Remove the epoxy resin from the cement matrix obtained in Step 3, and then soak it in a 1000ml beaker filled with 2mol / L KOH solution for 5 days. During soaking, the mouth of the beaker needs to be sealed with plastic wrap to prepare a cement matrix with energy storage capacity.

[0048] Step 5: Encapsulate the impregnated cement substrate with epoxy resin, covering all four sides (front, back, left, and right). The epoxy resin at the edges of the top and bottom surfaces should extend 5mm beyond the surface. Next, apply 5g of Osbon A528 graphite conductive adhesive to the top and bottom surfaces, ensuring it is fully in contact with the cement substrate. Then, insert a 70mm long, 1mm radius copper wire into the graphite conductive adhesive. Next, cover the graphite conductive adhesive with a 0.1mm*30mm*30mm copper sheet, ensuring it is in full contact with the adhesive. Finally, seal the top and bottom surfaces with epoxy resin, ensuring it is in close contact with the other surfaces, completely encapsulating the cement substrate without gaps. This yields the cement-based supercapacitor.

[0049] Compared to the cement-based supercapacitor prepared in Example 1, the cement-based supercapacitor prepared in Comparative Example 3 did not contain sodium dodecyl sulfate, resulting in less foam and smaller foam volume. Consequently, the porosity of the cement-based supercapacitor was also lower, and it could hold less KOH solution. This resulted in higher conductivity and poorer capacitance of the cement-based supercapacitor.

[0050] Comparative Example 4 A method for controlling the pore structure of cement-based supercapacitors by inducing heating tropism specifically includes the following steps: Step 1: Using sodium dodecyl sulfate and laboratory water as raw materials, the raw materials are mixed at a mass ratio of sodium dodecyl sulfate to water of 4:1000 to prepare foam that meets the requirements for improving the porosity of cement matrix.

[0051] Step 2: Using cement, sand, laboratory water, water-reducing agent, and foam as raw materials, the cement is P·O 42.5 ordinary Portland cement, the sand is Chinese ISO standard sand with a particle size of 0.08-2.0mm, and the water-reducing agent is PCA-I polycarboxylate high-performance water-reducing agent. The mass ratio of each raw material and foam is 1000:1800:350:2.2:83. First, mix the weighed cement and standard sand evenly, then add laboratory water and water-reducing agent in sequence and stir evenly to prepare cement slurry. Then, add the foam in a measured amount to the cement slurry, stir evenly, pour into a 30*30*30mm mold, let it stand for 24 hours, and then demold to prepare the cement matrix.

[0052] Step 3: The pore structure of the prepared cement matrix is ​​regulated by heat-induced orientation. This involves encapsulating the four sides of the cement matrix with epoxy resin and then drying it at 60°C for 3 days in an electrically heated constant-temperature drying oven. The epoxy resin used is a UV-cured resin, extruded onto the surface of the cement matrix and cured by ultraviolet light. 20g is used on each side, ensuring complete encapsulation of all four sides to prepare a cement matrix that meets the requirements for pore connectivity and orientation.

[0053] Step 4: Use a small shovel to remove the epoxy resin from the cement matrix obtained in step 3, and then soak it in a 1000ml beaker filled with 2mol / L KOH solution for 5 days. During soaking, the mouth of the beaker needs to be sealed with plastic wrap to prepare a cement matrix with energy storage capacity.

[0054] Step 5: Encapsulate the impregnated cement substrate with epoxy resin, covering all four sides (front, back, left, and right). The epoxy resin at the edges of the top and bottom surfaces should extend 5mm beyond the surface. Next, apply 5g of Osbon A528 graphite conductive adhesive to the top and bottom surfaces, ensuring it is fully in contact with the cement substrate. Then, insert a 70mm long, 1mm radius copper wire into the graphite conductive adhesive. Next, cover the graphite conductive adhesive with a 0.1mm*30mm*30mm copper sheet, ensuring it is in full contact with the adhesive. Finally, seal the top and bottom surfaces with epoxy resin, ensuring it is in close contact with the other surfaces, completely encapsulating the cement substrate without gaps. This yields the cement-based supercapacitor.

[0055] Compared to the cement-based supercapacitor prepared in Example 1, the cement-based supercapacitor prepared in Comparative Example 4 did not contain sodium carboxymethyl cellulose, which made the foam easily breakable. As a result, the porosity of the cement-based supercapacitor was also smaller, and it could hold less KOH solution. Consequently, the cement-based supercapacitor had higher conductivity and poorer capacitance.

[0056] Example of effect The cement-based supercapacitors prepared in Example 1 and Comparative Examples 1 and 2 were subjected to X-CT tests, AC impedance tests, and cyclic voltammetry tests in sequence.

[0057] from Figure 2 As can be seen, the total porosity and connected porosity of the cement-based supercapacitor in Example 1 are lower than those in Comparative Example 1, while the closed porosity is higher. This is mainly because directional induction reduces the migration path of water vapor in the horizontal direction, hinders the expansion of pores in the horizontal direction, and prevents closed pores from transforming into connected pores.

[0058] from Figure 3 As can be seen, the relative deviation of the throat area in the Z-axis direction of the cement-based supercapacitor in Example 1 is close to 10%, and the relative deviation of the number of throats in the Z-axis direction is close to 9%, indicating that the pores exhibit directional behavior in the Z-axis direction. The pores of the cement-based supercapacitors prepared in Examples 2-3 also exhibit directional behavior. The relative deviations of the throat area and the number of throats in the three directions of the cement-based supercapacitor in Comparative Example 1 are all within 5%, indicating that the pores do not exhibit directional behavior. The relative deviations of the throat area and the number of throats in the three directions of the cement-based supercapacitor in Comparative Example 2 are all within 5%, indicating that the pores do not exhibit directional behavior.

[0059] from Figure 5-7As can be seen, the cement-based supercapacitor of Example 1 has better conductivity than Comparative Examples 1 and 2, and exhibits better conductivity at different AC frequencies. This is because heating directional induction makes the pores directional, making ion transport more efficient, thereby increasing conductivity.

[0060] At scan rates of 100 mV / s and 80 mV / s, the area under the CV curve of the cement-based supercapacitor in Comparative Example 2 was larger than that in Comparative Example 1. However, at scan rates of 60, 40, and 20 mV / s, the area under the CV curve of the cement-based supercapacitor in Comparative Example 2 was smaller than that in Comparative Example 1. This is because when the scan rate is high, the ions in Comparative Example 2 shuttle rapidly, and the ions mainly pass through the main path with a large pore size, resulting in a higher specific capacitance. As the scan rate decreases, the ions in Comparative Example 2 will pass through the path with a smaller pore size. Since these smaller pore paths may have "defects," such as narrow or tortuous connecting paths, or local blockages, ion transport is hindered and accumulates, and there may even be a phenomenon where ions cannot reach the effective reaction site, resulting in a lower specific capacitance than that in Comparative Example 1.

[0061] from Figure 5-8 As can be seen, the CV curve integral area of ​​the cement-based supercapacitor in Example 1 is larger than that in Comparative Examples 1 and 2, indicating a larger specific capacitance and the ability to store more charge. This is because the pores in Example 1 exhibit directional properties and good pore connectivity, providing a more efficient path for ion migration. Under the directional induction in the Z-axis direction, the pores expand along the Z-axis, becoming elongated and narrower, increasing the specific surface area and thus increasing the adsorption area for ions, thereby improving the specific capacitance value.

[0062] The charging and discharging process of the cement-based supercapacitor prepared from the first to the fifth steps is as follows: Figure 9As shown, specifically, the internal pores of cement-based supercapacitors are divided into three types. Pore 1 is a closed pore, where anions are adsorbed on the inner wall of the pore near the positive electrode, and cations are adsorbed on the inner wall of the pore near the negative electrode. Closed pores reduce charge storage efficiency because electrolyte ions have difficulty entering the closed pores. Moreover, closed pores occupy the internal space of the material but do not improve capacitance performance, resulting in a decrease in the energy density of the material. Pore 2 is a non-directional interconnected pore, where anions are adsorbed on the inner wall of the pore near the positive electrode, and cations are adsorbed on the inner wall of the pore near the negative electrode. The adsorption area is larger than that of closed pores, contributing more to the energy storage capacity. This is because the ion diffusion rate of interconnected pores is fast, there are many transport paths, and the charging process proceeds quickly. In addition, the greater the interconnected porosity, the more electrolyte solution is inside the cement-based energy storage structure, the more ions can be adsorbed, and the more energy can be stored. Pore ​​3 is a directional interconnected pore. The pore is narrow and long. Anions will be adsorbed on the inner wall of the pore near the positive electrode, and cations will be adsorbed on the inner wall of the pore near the negative electrode. The adsorption area is larger than that of non-directional interconnected pores, and it can store the most energy.

[0063] The cement-based supercapacitor in Comparative Example 1 has pores mainly composed of pores 1 and pores 2, with pores 2 accounting for a larger proportion and having a greater energy storage capacity. The cement-based supercapacitor in Comparative Example 2 has pores mainly composed of pores 2, but the pores in Comparative Example 2 have not undergone directional induction, resulting in more "defect" pathways and thus a lower energy storage capacity than Comparative Example 1. The cement-based supercapacitor in Example 1 has pores mainly composed of pores 3; therefore, the energy storage capacity of Example 1 is stronger than that of Comparative Examples 1 and 2.

[0064] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for controlling the pore structure of a cement-based supercapacitor, characterized in that, Includes the following steps: (1) Sodium dodecyl sulfate, sodium carboxymethyl cellulose and water are mixed to obtain foam; (2) Mix cement and sand evenly, then add water and water-reducing agent and stir to obtain cement paste, then add the foam prepared in step (1) and stir evenly before pouring into the mold, let it stand and then demold to obtain cement matrix; (3) After sealing and curing part of the surface of the cement matrix with epoxy resin, heat it, then remove the sealing material of the heated cement matrix, and then immerse the cement matrix in potassium hydroxide solution to obtain the immersed cement matrix. (4) Use epoxy resin to encapsulate the periphery of the cement substrate after soaking, and then cure it. Apply graphite conductive adhesive to the upper and lower surfaces of the cured cement substrate, insert a copper wire into the graphite conductive adhesive, then cover the copper sheet on the graphite conductive adhesive, and finally seal the upper and lower surfaces of the cement substrate with epoxy resin to obtain a cement-based supercapacitor.

2. The method for regulating the pore structure of a cement-based supercapacitor as described in claim 1, characterized in that, The mass ratio of sodium dodecyl sulfate, sodium carboxymethyl cellulose, and water is (1~20):(1~10):1000.

3. The method for regulating the pore structure of cement-based supercapacitors as described in claim 1, characterized in that, The mass ratio of cement, sand, water, water-reducing agent and foam is 1000:(1500~2000):(300~400):(1~4):(60~100).

4. The method for regulating the pore structure of cement-based supercapacitors as described in claim 1, characterized in that, The cement matrix is ​​a quadrangular prism; in step (3), the four surfaces of the cement matrix are encapsulated and cured with epoxy resin.

5. The method for regulating the pore structure of cement-based supercapacitors according to claim 1, characterized in that: In step (3), the heating temperature is 60℃~120℃ and the time is 3~7 days.

6. The method for regulating the pore structure of cement-based supercapacitors as described in claim 1, characterized in that, The concentration of the potassium hydroxide solution is 1~5 mol / L; the soaking time is 1~5 days.

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