Concrete super capacitor based on phase change particle microscopic dielectric layer and preparation method thereof

Abstract

The invention provides a preparation method of a concrete super capacitor based on a phase change particle microscopic dielectric layer, and the method specifically comprises the following steps: 1, preparing a basic structure of the concrete super capacitor, specifically comprising the following structures: 11, mixing a concrete base material which comprises cement, aggregate and water; 12, a conductive phase is doped into the concrete base material according to a preset proportion, a basic conductive network is constructed, and the conductive phase is micro carbon black particles; 13, an intelligent additive is doped into a product obtained in the step 12 according to a preset proportion, the intelligent additive is multi-walled carbon nanotube doped polypyrrole coated paraffin microparticles, a conductive micro-network structure is formed in the concrete, a basic structure of the concrete super capacitor is obtained, and in the basic structure of the concrete super capacitor, a conductive micro-network structure is formed; the internal micro carbon black particles form a three-dimensional conductive network; and 2, carrying out in-situ electric triggering on the basic structure of the concrete super capacitor to form a microscopic dielectric layer, and obtaining the concrete super capacitor.

Description

Technical Field

[0001] This invention relates to the field of concrete capacitors, and more particularly to a concrete supercapacitor based on a phase change particle micro-dielectric layer and its preparation method. Background Technology

[0002] Existing concrete capacitor technology achieves conductivity by adding conductive materials such as carbon black and metal powder to concrete, fulfilling the basic requirement of using concrete as an electrode. Then, by placing a dielectric material within the conductive concrete, the basic structure of the concrete capacitor is achieved, enabling a certain degree of energy storage. However, existing concrete capacitors have the following problems: 1) Existing concrete capacitors, such as Figure 1 As shown, an electric double-layer capacitor (EDLC) design was adopted. Although the microstructure of concrete was used to achieve the adsorption of charged ions, and the positive and negative electrodes needed to form an electric double layer through an electrolyte (such as KCl solution), direct contact between the two electrodes would cause an electronic short circuit. The separator, acting as an insulating layer, prevents direct electron flow between the electrodes while allowing ions to migrate through the pores. Therefore, the electrode distance still cannot escape the limitations of traditional capacitor dielectric materials, and its energy storage capacity is not fully utilized. 2) Existing concrete capacitors utilize ion-permeable insulating materials. In practice, the concrete capacitor is bounded by the insulating material, forming a weak surface and reducing the overall integrity of the concrete structure. This is the biggest challenge in the application of concrete capacitors. 3) Existing concrete capacitors use ion-permeable insulating materials as the contact area, resulting in a limited electrode area, which is usually the same size as the concrete structure, greatly limiting the capacity of the concrete capacitor. Summary of the Invention

[0003] The main objective of this invention is to provide a concrete supercapacitor based on a phase change particle micro-dielectric layer and its preparation method. By using the phase change particle-based micro-dielectric layer technology, the capacity of the concrete supercapacitor can be increased by several orders of magnitude.

[0004] To achieve the above objectives, the technical solution adopted by this invention is as follows: a method for preparing a concrete supercapacitor based on a phase change particle micro-dielectric layer, specifically including the following steps: Step 1: Prepare the basic structure of the concrete supercapacitor, specifically including the following structure: Step 11: Mix the concrete substrate, which includes cement, aggregate, and KCl aqueous solution; Step 12: Add a conductive phase to the concrete substrate in a predetermined ratio to construct a basic conductive network. The conductive phase is micro carbon black particles. Step 13: Add the smart additive to the product from Step 12 in a predetermined ratio. The intelligent additive is a multi-walled carbon nanotube-doped polypyrrole-coated paraffin microparticle, which forms a conductive micro-network structure inside the concrete, thus obtaining the basic structure of the concrete supercapacitor. In the basic structure of the concrete supercapacitor, the internal micro carbon black particles constitute a three-dimensional conductive network. Step 2: In-situ electrical triggering is performed on the foundation structure of the concrete supercapacitor to form a micro-dielectric layer, thus obtaining the concrete supercapacitor.

[0005] Preferably, step two specifically includes the following steps: Step 21: Connect a high-voltage power supply to the opposite sides of the foundation structure of the concrete supercapacitor and apply a controllable instantaneous high-voltage pulse; Step 22: Utilizing the Joule heating effect, local heating is generated at the weakest link in the three-dimensional conductive network. At the local heating point, the paraffin in the multi-walled carbon nanotube-doped polypyrrole-coated paraffin microparticles melts and flows. The three-dimensional conductive network of carbon black particles is locally isolated by the melted paraffin, forming a microscopic insulating region. The microscopic insulating region blocks the original conductive path, forming multiple distributed microscopic capacitor units, thus obtaining the concrete supercapacitor.

[0006] Preferably, the method further includes step three, which involves repairing the concrete supercapacitor whose performance has degraded, specifically including the following steps: Step 31: Apply a momentary high-voltage pulse to the concrete supercapacitor to be repaired; Step 32: After applying a transient high-voltage pulse, the current will preferentially pass through the conductive path where a short circuit occurs. The Joule heating effect will be concentrated again on the conductive path where a short circuit occurs, triggering the melting and flow of paraffin in the polypyrrole-coated paraffin microparticles doped with multi-walled carbon nanotubes in the corresponding area. This will re-form a local micro-insulating area around the corresponding area, restoring or partially restoring the capacitance function.

[0007] Preferably, the preparation method of the multi-walled carbon nanotube-doped polypyrrole-coated paraffin microparticles is as follows: Step a: Pre-emulsify the paraffin microparticles to obtain a paraffin emulsion; Step b: Functionalize multi-walled carbon nanotubes to obtain MWCNT dispersion; Step c: Perform in-situ interfacial polymerization coating on the paraffin emulsion and MWCNT dispersion; Step d: Process the product obtained in step c to obtain multi-walled carbon nanotube-doped polypyrrole-coated paraffin microparticles.

[0008] Preferably, step a specifically includes the following steps: Step a1: Mix solid paraffin with a phase change temperature of 58-62℃ with deionized water at a mass ratio of 1:10, and add sodium dodecyl sulfate as an emulsifier. Step a2: The product from step a1 is mechanically stirred in a water bath at a certain temperature until it melts, so that the paraffin is completely emulsified to form a micron-sized stable emulsion, which is the paraffin emulsion. Preferably, step b specifically includes the following steps: Step b1: Place MWCNT in a mixed acid prepared by a volume ratio of concentrated H2SO4 and concentrated HNO3 of 3:1, and sonicate it at a certain temperature for a period of time to remove metal impurities and introduce hydroxyl and carboxyl functional groups. Step b2: After centrifuging and washing the product from step b1 until neutral, mix it with an aqueous solution of polyvinylpyrrolidone and then sonicate for a period of time to obtain a functionalized MWCNT dispersion.

[0009] Preferably, step c specifically includes the following steps: Step c1: Constructing the hybrid system: The functionalized MWCNT dispersion was added to the paraffin emulsion and stirred for a period of time under nitrogen protection to obtain the MWCNT-paraffin emulsion; Step c2, pyrrole monomer loading: Pyrrole monomer is added dropwise to the MWCNT-paraffin emulsion at a pyrrole monomer:paraffin molar ratio of 1:8, and the temperature is controlled at a certain temperature. Step c3: Slowly add a certain concentration of ammonium persulfate ethanol solution to the product of step c2, so that the molar ratio of ammonium sulfate to pyrrole monomer is 1:1. React at a certain temperature for a period of time, and the pyrrole monomer polymerizes to obtain polypyrrole. The polypyrrole forms a continuous conductive coating layer at the paraffin-MWCNT interface.

[0010] Preferably, step d specifically includes the following steps: Step d1: Cool the product from step c3 to a specified temperature at a certain rate while continuously stirring; Step d2: Transfer the emulsion obtained in step d1 to an ice water bath and set it for a period of time; Step d3: Wash the product from step d2 three times with ethanol and deionized water in sequence. Step d4: The product of step d3 is vacuum dried at a certain temperature for a period of time to obtain a black powdery composite phase change material, which is multi-walled carbon nanotube-doped polypyrrole-coated paraffin microparticles.

[0011] Compared with the prior art, the present invention has the following beneficial effects: 1) Adding graphite particles to concrete creates conductive microstructure pathways within the concrete crystal microstructure. 2) By adopting phase change particle micro dielectric layer technology, the capacitor contact is transformed from macroscopic to microscopic, which greatly increases the contact area of ​​concrete capacitor electrodes and greatly reduces the spacing between concrete capacitor electrodes, thereby increasing the capacity of concrete supercapacitors by several orders of magnitude. 3) Adding KCl aqueous solution to concrete causes the K+ and Cl- ions to aggregate with graphite particles, and the negatively charged carbon black surface adsorbs the positive ions (K+, Cl-) in the solution. + The positively charged carbon black surface adsorbs negative ions (Cl). - ); 4) The double layer thickness is only 1~10 nm, which is equivalent to a molecular-level dielectric layer. The double layer plus the insulating point thickness is only 1 μm, which is the actual dielectric layer thickness. The electrode distance is significantly reduced and the capacitance is significantly improved. 5) If the concrete supercapacitor of the present invention is damaged or wetted, causing the local conductive path to reconnect, the application of instantaneous high voltage will repeat the above process at the new weak point (where the resistance is the greatest and the heat is the most), forming a new insulation point and maintaining the operation of the concrete super double-layer capacitor. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of a concrete capacitor in the existing technology; Figure 2 and Figure 3 This is a schematic diagram of the concrete supercapacitor of the present invention. Detailed Implementation

[0013] The following description is intended to disclose the invention and enable those skilled in the art to implement it. The preferred embodiments described below are merely examples, and other obvious variations will occur to those skilled in the art.

[0014] A method for preparing a concrete supercapacitor based on a phase change particle micro-dielectric layer includes the following steps: Step 1: Prepare the basic structure of the concrete supercapacitor, specifically including the following structure: Step 11: Mix the concrete substrate, which includes cement, aggregate, and KCl aqueous solution. The concentration of the KCl aqueous solution is 0.1-0.5 mol / L, and the mass ratio of cement:aggregate:KCl aqueous solution is 1:2:0.4. Step 12: Add a conductive phase to the concrete substrate according to a predetermined ratio to construct a basic conductive network. Preferably, the conductive phase is micro carbon black particles (CB), and the conductive phase accounts for 3 wt% of the total concrete supercapacitor. Step 13: Add a smart additive according to a predetermined ratio. The smart additive is multi-walled carbon nanotube-doped polypyrrole (PPy) coated paraffin microparticles. The multi-walled carbon nanotube-doped polypyrrole (PPy) coated paraffin microparticles have high electrical conductivity (10–100 S / cm), reaching metallic level conductivity. They have metallic level conductivity before phase transition and form a conductive micro-network structure inside the concrete, thus obtaining the basic structure of the concrete supercapacitor. In the basic structure of the concrete supercapacitor, the internal micro carbon black particles constitute a three-dimensional conductive network, serving as the biphase electrodes of the capacitor. The electrodes are interpenetrating networks rather than completely isolated. Preferably, the smart additive accounts for 1.5 wt% of the entire concrete supercapacitor.

[0015] Step 2: In-situ electrical triggering is performed on the foundation structure of the concrete supercapacitor to form a micro-dielectric layer, thus obtaining the concrete supercapacitor. This specifically includes the following steps: Step 21: Connect a high-voltage power supply to the opposite sides of the foundation structure of the concrete supercapacitor (as the two electrodes of the capacitor) and apply a controllable instantaneous high-voltage pulse. Step 22: Utilizing the Joule heating effect, local high temperatures are generated at the weakest link in the conductive network (the point of maximum resistance, the point of poor contact). At the local high temperature point, the paraffin in the paraffin microparticles coated with multi-walled carbon nanotubes doped with polypyrrole (PPy) melts and flows. The three-dimensional conductive network of carbon black particles is locally isolated by the melted paraffin, forming a micro-insulating region. These in-situ generated insulating products block the original conductive path through the micro-insulating region. Step 23: "Break circuits" are formed in countless microscopic insulating regions, which divides the continuous conductive network at the microscopic scale and forms a large number of distributed microscopic capacitor units, which play the role of in-situ generated distributed dielectric layer, thus obtaining concrete supercapacitor.

[0016] The working principle of the concrete supercapacitor of this invention is as follows: After concrete is poured and cured, it is a good conductor and does not possess capacitive properties. When an instantaneous voltage is applied between any two points A and B in the concrete, an instantaneous current forms in the conductive network of the concrete's internal microstructure. Each micro-branch of the conductive network generates internal energy at the point of maximum resistance. Local overheating of the polypyrrole (PPy)-coated paraffin microparticles doped with multi-walled carbon nanotubes causes the core material of the microspheres to decompose, forming insulating points at these nodes. All the insulating points inside the concrete combine to form a three-dimensional microscopic "in-situ generated" dielectric layer. After the formation of this three-dimensional microscopic "in-situ generated" dielectric layer, an overall open circuit is formed between points A and B on the concrete surface, isolating the two electrodes. The charging process involves applying a voltage between points A and B in the concrete. K+ and Cl- ions inside the three-dimensional microscopic "in-situ generated" dielectric layer begin to move under the influence of electromotive force. The negatively charged carbon black surface adsorbs positive ions (K+, Cl-) from the solution. + The positively charged carbon black surface adsorbs negative ions (Cl). - ), forming a concrete super double-layer capacitor; If concrete is damaged (cracked) or exposed to a humid environment for a long time, causing moisture to penetrate, the moisture or cracks may reconnect some conductive areas separated by insulation points, resulting in a decrease in capacitance or a short circuit. The concrete supercapacitor can be repaired. Therefore, this invention also includes step three: repairing the concrete supercapacitor, specifically including the following steps: Step 31: Apply a momentary high-voltage pulse to the concrete supercapacitor to be repaired; Step 32: After applying a transient high-voltage pulse, the current preferentially flows through the newly formed, low-resistance damage path or moisture path. Along these paths, the Joule heating effect is concentrated again, triggering the same reaction in the residual or newly exposed multi-walled carbon nanotube-doped polypyrrole (PPy) coated paraffin microparticles in the area (which may be at or near the damage site). This causes the local micro-insulating points to reform around the damaged / water-permeable area, restoring or partially restoring the capacitance function.

[0017] The preparation method of the multi-walled carbon nanotube-doped polypyrrole (PPy)-coated paraffin microparticles is as follows: Step a, pre-emulsifying the paraffin microparticles, specifically includes the following steps: Step a1: Mix solid paraffin with a phase change temperature of 58-62℃ with deionized water at a mass ratio of 1:10, and add 0.5-1wt% sodium dodecyl sulfate (SDS) as an emulsifier; Step a2: The product from step a1 is mechanically stirred in a water bath at 70-80℃ at a speed of 1000-1500 rpm until it melts, so that the paraffin is completely emulsified to form a micron-scale (1-10μm) stable emulsion, which is a paraffin emulsion. Step b: Functionalize multi-walled carbon nanotubes (MWCNTs), specifically including the following steps: Step b1: Place MWCNT in a mixed acid prepared by a volume ratio of concentrated H2SO4 and concentrated HNO3 of 3:1, and sonicate at 60°C for 2 hours to remove metal impurities and introduce hydroxyl and carboxyl functional groups. Step b2: After centrifuging and washing the product from step b1 until neutral, mix it with a 1 wt% polyvinylpyrrolidone (PVP) aqueous solution. The concentration of MWCNT in the mixed solution is 0.5 mg / mL. Then, sonicate for 30 min to obtain the functionalized MWCNT dispersion. Step c, perform in-situ interface aggregation and overlay, specifically including the following steps: Step c1: Constructing the hybrid system: Add the functionalized MWCNT dispersion (3-5% of the final product mass) to the paraffin emulsion and stir for 30 min under nitrogen protection to obtain the MWCNT-paraffin emulsion; Step c2, pyrrole monomer loading: Pyrrole monomer is added dropwise to the MWCNT-paraffin emulsion at a pyrrole monomer:paraffin molar ratio of 1:8, and the temperature is controlled at 65℃ (above 62℃). Step c3: Slowly add 0.1 mol / L ammonium persulfate (APS) ethanol solution to the product of step c2, so that the molar ratio of ammonium sulfate to pyrrole monomer is 1:1. React at 65°C for 24 h. The pyrrole monomer polymerizes to obtain polypyrrole. The polypyrrole forms a continuous conductive coating layer at the paraffin-MWCNT interface. Step d: The product obtained in step c is processed as follows: Step d1: Cool the product from step c3 from 65°C to 25°C at a rate of 2°C / min, and continue stirring to prevent particle aggregation. Step d2: Transfer the emulsion obtained in step d1 to an ice water bath (5°C) for rapid setting for 10 minutes; Step d3: Wash the product from step d2 three times with ethanol and deionized water in sequence. Step d4: The product from step d3 is vacuum dried at 50°C for 12 hours to obtain a black powdery composite phase change material, namely, multi-walled carbon nanotube-doped polypyrrole (PPy) coated paraffin microparticles.

[0018] Performance testing: The concrete supercapacitor prepared using the above steps was tested, and the following performance data were obtained:

[0019] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention. The scope of protection claimed by the appended claims and their equivalents is defined.

Claims

1. A method for preparing a concrete supercapacitor based on a phase change particle micro-dielectric layer, specifically including the following steps: Step 1: Prepare the basic structure of the concrete supercapacitor, specifically including the following structure: Step 11: Mix the concrete substrate, which includes cement, aggregate, and KCl aqueous solution; Step 12: Add a conductive phase to the concrete substrate in a predetermined ratio to construct a basic conductive network. The conductive phase is micro carbon black particles. Step 13: Add the smart additive to the product from Step 12 in a predetermined ratio. The intelligent additive is a multi-walled carbon nanotube-doped polypyrrole-coated paraffin microparticle, which forms a conductive micro-network structure inside the concrete, thus obtaining the basic structure of the concrete supercapacitor. In the basic structure of the concrete supercapacitor, the internal micro carbon black particles constitute a three-dimensional conductive network. Step 2: In-situ electrical triggering is performed on the foundation structure of the concrete supercapacitor to form a micro-dielectric layer, thus obtaining the concrete supercapacitor.

2. The preparation method according to claim 1, characterized in that, Step two specifically includes the following steps: Step 21: Connect a high-voltage power supply to the opposite sides of the foundation structure of the concrete supercapacitor and apply a controllable instantaneous high-voltage pulse; Step 22: Utilizing the Joule heating effect, local heating is generated at the weakest link in the three-dimensional conductive network. At the local heating point, the paraffin in the multi-walled carbon nanotube-doped polypyrrole-coated paraffin microparticles melts and flows. The three-dimensional conductive network of carbon black particles is locally isolated by the melted paraffin, forming a microscopic insulating region. The microscopic insulating region blocks the original conductive path, forming multiple distributed microscopic capacitor units, thus obtaining the concrete supercapacitor.

3. The preparation method according to claim 1, characterized in that, It also includes step three, which is used to repair concrete supercapacitors whose performance has degraded, and specifically includes the following steps: Step 31: Apply a momentary high-voltage pulse to the concrete supercapacitor to be repaired; Step 32: After applying a transient high-voltage pulse, the current will preferentially pass through the conductive path where a short circuit occurs. The Joule heating effect will be concentrated again on the conductive path where a short circuit occurs, triggering the melting and flow of paraffin in the polypyrrole-coated paraffin microparticles doped with multi-walled carbon nanotubes in the corresponding area. This will re-form a local micro-insulating area around the corresponding area, restoring or partially restoring the capacitance function.

4. The preparation method according to claim 1, characterized in that, The preparation method of the multi-walled carbon nanotube-doped polypyrrole-coated paraffin microparticles is as follows: Step a: Pre-emulsify the paraffin microparticles to obtain a paraffin emulsion; Step b: Functionalize multi-walled carbon nanotubes to obtain MWCNT dispersion; Step c: Perform in-situ interfacial polymerization coating on the paraffin emulsion and MWCNT dispersion; Step d: Process the product obtained in step c to obtain multi-walled carbon nanotube-doped polypyrrole-coated paraffin microparticles.

5. The preparation method according to claim 4, characterized in that, Step a specifically includes the following steps: Step a1: Mix solid paraffin with a phase change temperature of 58-62℃ with deionized water at a mass ratio of 1:10, and add sodium dodecyl sulfate as an emulsifier. Step a2: The product from step a1 is mechanically stirred in a water bath at a certain temperature until it melts, so that the paraffin wax is completely emulsified to form a micron-sized stable emulsion, which is the paraffin wax emulsion.

6. The preparation method according to claim 5, characterized in that, Step b specifically includes the following steps: Step b1: Place MWCNT in a mixed acid prepared by a volume ratio of concentrated H2SO4 and concentrated HNO3 of 3:1, and sonicate it at a certain temperature for a period of time to remove metal impurities and introduce hydroxyl and carboxyl functional groups. Step b2: After centrifuging and washing the product from step b1 until neutral, mix it with an aqueous solution of polyvinylpyrrolidone and then sonicate for a period of time to obtain a functionalized MWCNT dispersion.

7. The preparation method according to claim 6, characterized in that, Step c specifically includes the following steps: Step c1: Constructing the hybrid system: The functionalized MWCNT dispersion was added to the paraffin emulsion and stirred for a period of time under nitrogen protection to obtain the MWCNT-paraffin emulsion; Step c2, pyrrole monomer loading: Pyrrole monomer is added dropwise to the MWCNT-paraffin emulsion at a pyrrole monomer:paraffin molar ratio of 1:8, and the temperature is controlled at a certain temperature. Step c3: Slowly add a certain concentration of ammonium persulfate ethanol solution to the product of step c2, so that the molar ratio of ammonium sulfate to pyrrole monomer is 1:

1. React at a certain temperature for a period of time, and the pyrrole monomer polymerizes to obtain polypyrrole. The polypyrrole forms a continuous conductive coating layer at the paraffin-MWCNT interface.

8. The preparation method according to claim 7, characterized in that, Step d specifically includes the following steps: Step d1: Cool the product from step c3 to a specified temperature at a certain rate while continuously stirring; Step d2: Transfer the emulsion obtained in step d1 to an ice water bath and set it for a period of time; Step d3: Wash the product from step d2 three times with ethanol and deionized water in sequence. Step d4: The product of step d3 is vacuum dried at a certain temperature for a period of time to obtain a black powdery composite phase change material, which is multi-walled carbon nanotube-doped polypyrrole-coated paraffin microparticles.

9. A concrete supercapacitor based on a phase change particle micro-dielectric layer, characterized in that, Prepared using the preparation method described in any one of claims 1-8.

Images