Alkali-activated concrete-based supercapacitor and assembling method and application thereof

Abstract

The invention provides an alkali-activated concrete-based supercapacitor and an assembling method and application thereof. The supercapacitor is formed by assembling an electrode plate, a diaphragm and an electrolyte. The diaphragm is prepared from alkali-activated concrete prepared from fly ash or metakaolin, mineral powder, water, an alkali activator and coarse aggregate with a certain particle size through cutting, cleaning, drying and electrolyte impregnation. The diaphragm has a cross-scale pore network of gel pore-capillary pore-macropore-pore, provides an efficient channel for ion transmission, and provides electrochemical performance comparable with that of a traditional supercapacitor prepared by adopting a commercial diaphragm for the supercapacitor. The invention further provides an assembling method of the super capacitor. The core innovation of the invention lies in that the super capacitor is successfully constructed on the macroscopic scale of concrete for the first time, excellent balance of mechanical strength and electrochemical performance of the material is realized, and the super capacitor has significant application potential in preparation of buildings or components with both a structural bearing function and an electrochemical energy storage function.

Description

Technical Field

[0001] This invention belongs to the field of supercapacitor technology, specifically relating to an alkali-activated concrete-based supercapacitor and its assembly method, and also to the application of the above-mentioned alkali-activated concrete-based supercapacitor in the preparation of building or infrastructure components that have both structural load-bearing function and electrochemical energy storage function. Background Technology

[0002] Climate change, infrastructure upgrades, and the need for sustainable smart city solutions are making it increasingly urgent to transform concrete from a passive material into a functional, active one. Cement-based supercapacitors, as a novel energy storage device, hold promise as a key medium between clean energy and end-users. Supercapacitors offer advantages such as fast charging and discharging speeds and long cycle lives, while cement-based supercapacitors can overcome geographical limitations by being embedded in building structures, achieving both load-bearing and energy storage functions. Furthermore, the flame-retardant and explosion-proof properties of cement-based supercapacitors fundamentally eliminate safety hazards.

[0003] Cement-based supercapacitors consist of four parts: a positive electrode, a separator, a negative electrode, and an electrolyte. Cement-based materials are typically used as the separator. To improve the ionic conductivity of cement-based separators, three methods exist in existing technologies: 1) Mixing the electrolyte, ionic additives, water, and cement in one batch. While this method is simple, the electrolyte severely hinders the cement hydration process, affecting the mechanical and durability properties of the separator material; 2) Adding air-entraining agents or foaming agents to the cement. This method increases the porosity of the separator material, but at the cost of mechanical properties. Furthermore, the adjustment of pore size at the microscale is random, making it impossible to achieve uniform electrochemical performance; 3) The ice template method. This method can effectively reduce the tortuosity of the separator, but the preparation process is complex and limited to laboratory research, preventing large-scale applications.

[0004] Furthermore, existing research is based on cement paste systems. Cement has inherent drawbacks such as shrinkage, brittleness, poor durability, and high cost, making it difficult to meet the application requirements of practical engineering. Compared with cement, concrete materials have significantly improved volume stability, mechanical properties, and durability, and effectively reduce material and environmental costs. However, due to its complex multiphase and heterogeneous system, it also places higher demands on manufacturing processes. More importantly, although the addition of aggregates can improve the mechanical properties and volume stability of concrete materials, aggregates, as large insulating particles, greatly hinder the ionic conductivity of the membrane, leading to a research bottleneck.

[0005] Based on this, a concrete-based supercapacitor and its preparation method are provided, which overcomes the insulating properties of aggregates, ensures a balance between mechanical and electrochemical properties, and realizes the practical application of concrete-based diaphragms in supercapacitors on a macroscopic scale. This is a technical problem that urgently needs to be solved. Summary of the Invention

[0006] One of the objectives of this invention is to provide an alkali-activated concrete-based supercapacitor that can overcome the insulating properties of aggregates while ensuring a balance between mechanical and electrochemical properties.

[0007] The second objective of this invention is to provide a method for assembling an alkali-activated concrete-based supercapacitor.

[0008] The third objective of this invention is to provide an application of alkali-activated concrete-based supercapacitor in the preparation of building or infrastructure components that combine structural load-bearing function and electrochemical energy storage function.

[0009] One of the technical solutions adopted by the present invention to achieve the objective is to provide an alkali-activated concrete-based supercapacitor, including a positive electrode, a negative electrode, a diaphragm, and an electrolyte; The diaphragm is an alkali-activated concrete-based diaphragm. By weight, the raw material composition of the alkali-activated concrete-based diaphragm includes: 160-180 parts of fly ash and / or metakaolin; 160-180 parts of mineral powder; 1400-2100 parts of aggregate, the particle size of which is 3-5 mm; 133-147 parts of alkali activator; and 37-43 parts of water.

[0010] The overall concept and inventive principle of this invention are as follows: To achieve successful application of alkali-activated concrete-based diaphragms in supercapacitors and meet the mechanical and electrochemical performance requirements of supercapacitors, this invention optimizes the raw materials for alkali-activated concrete-based diaphragms. The most significant difference from conventional alkali-activated concrete is that the raw materials of this invention use only coarse aggregates of a single particle size, excluding fine aggregates (sand) used to provide continuous gradation. This "discontinuous gradation," unlike the "continuous gradation" in traditional processes, provides a high-strength skeleton for the concrete component while retaining macroscopic pores, ensuring its electrochemical performance as a diaphragm.

[0011] Furthermore, research revealed that when the coarse aggregate particle size is too large, the number of macropores formed is small but their size is large, severely weakening the mechanical properties of the membrane and increasing the membrane thickness, resulting in a longer ion transport path. Conversely, if the aggregate particle size is too small, it will block the pores, preventing the formation of an effective interconnected pore network and limiting ion migration. Therefore, this application limits the coarse aggregate particle size to the range of 3-5 mm to achieve a balance between mechanical and electrochemical properties.

[0012] Furthermore, the aluminosilicate raw materials in the formulation utilize a combination of fly ash or metakaolin and mineral powder, with the mineral powder content controlled at around 50%. This improves both the plastic viscosity of the slurry and the strength of the reaction products. Excessive mineral powder content is detrimental to the workability of the membrane and hinders the formation of microscopic pores. Simultaneously, the ratio of slurry to aggregate ensures that the membrane's interconnected porosity and tortuosity are within a reasonable range, improving ion transport rates and ensuring a balance between electrochemical and mechanical properties. The gel-capillary-macropore structure formed within the alkali-activated slurry material, working synergistically with macropores, enriches ion transport channels. In particular, the construction of macropores greatly promotes ion transport, significantly enhancing the device's electrochemical performance.

[0013] Furthermore, the aggregate includes one or more combinations of limestone, basalt, and granite.

[0014] Further, the alkaline activator comprises: 13-17 parts by weight of sodium hydroxide or potassium hydroxide and 120-130 parts by weight of sodium silicate or potassium silicate, specifically selected according to the type of cations in the electrolyte. Preferably, the alkaline activator is a combination of sodium hydroxide and sodium silicate, wherein the sodium hydroxide is a solid powder with a purity of 97%-99%; and the sodium silicate has a modulus of 2-2.3 and a solid content of 40%-45%.

[0015] Furthermore, the preparation method of the alkali-activated concrete-based diaphragm includes the following steps: S1. Prepare an alkaline activator solution by mixing water and alkaline activator. S2. Mix fly ash and / or metakaolin, mineral powder and aggregate evenly, then add alkali activator solution and continue mixing, then pour into mold, vibrate and compact in layers, demold after hardening and curing. S3. After curing, the alkali-activated concrete is cut, cleaned, dried, and then placed in an electrolyte solution for impregnation under vacuum conditions to obtain an alkali-activated concrete base diaphragm.

[0016] Further, in step S2, the mixing time of fly ash and / or metakaolin, mineral powder and aggregate is 2-3 minutes, and the alkaline activator solution is added and mixing continues for 2-3 minutes. Considering that in conventional vibration methods, the slurry tends to accumulate at the bottom of the mold and fall off with the aggregate, this invention prefers manual tamping to ensure the uniformity of the slurry composition and avoid the application performance of the diaphragm due to defects in the preparation process.

[0017] Furthermore, in step S3, the curing temperature is 20-30℃, the relative humidity is 90%-95%, and the curing time is 28 days.

[0018] Furthermore, in step S3, the cleaning is performed using ultrasonic cleaning, followed by vacuum drying at 50-70℃ for 12-48 hours to remove moisture. The immersion time in the electrolyte is 6-9 hours.

[0019] In conventional cement-based diaphragm preparation processes, the electrolyte is usually directly mixed with cement. This not only hinders the cement hydration process, causing strength loss, but also negatively impacts ion mobility as moisture evaporates later. In contrast, the diaphragm preparation process of this application first completes the preparation and curing of the diaphragm, then fully impregnates and absorbs the electrolyte before encapsulation. This avoids the adverse effects of the electrolyte on the mechanical properties of alkali-activated concrete and prevents the adverse effects of electrolyte moisture evaporation on ion mobility, thus ensuring electrochemical performance.

[0020] Furthermore, the positive and negative electrodes are respectively selected from activated carbon electrodes, manganese dioxide electrodes, and graphene electrodes, and the materials of the positive and negative electrodes may be the same or different. Specifically, the electrodes can be one of activated carbon electrode-activated carbon electrode combination, manganese dioxide electrode-activated carbon electrode combination, graphene electrode-graphene electrode combination, or manganese dioxide electrode-graphene electrode combination.

[0021] Preferably, both the positive and negative electrodes are activated carbon electrodes, and their preparation method includes the following steps: Activated carbon powder and conductive carbon black are mixed and ground, then polytetrafluoroethylene emulsion and anhydrous ethanol are added. The mixture is stirred thoroughly with a magnetic stirrer until the ethanol evaporates, resulting in a viscous agglomerate. The agglomerate is then coated onto a nickel foam current collector, pressed using a tablet press, dried in a vacuum drying oven, and cut to obtain the activated carbon electrode. The mass ratio of activated carbon, conductive carbon black, and polytetrafluoroethylene is (7.5-8.5):(0.5-1.5):(0.5-1.5); the conductive carbon black is Super P with a resistivity of 0.3-0.6 Ω / m; the solid content of the polytetrafluoroethylene emulsion is 55%-65%; and the loading of the activated carbon electrode sheet is 10 mg / cm³. 2 The dimensions are 40×50 mm.

[0022] Furthermore, the electrolyte is a 2-10 mol / L solution of NaOH, KOH, Na2SO4, or K2SO4; the supercapacitor is soft-packed using an aluminum-plastic film. Preferably, the electrolyte is a 6 mol / L solution of NaOH or KOH.

[0023] The second objective of this invention is to provide an assembly method for an alkali-activated concrete-based supercapacitor, as described in one objective of this invention. The alkali-activated concrete-based diaphragm is placed between the positive and negative electrodes, and the entire assembly is placed in a flexible packaging shell made of aluminum-plastic film. Electrolyte is injected, and the supercapacitor is obtained by vacuum sealing.

[0024] Furthermore, after injecting the electrolyte, the sample is allowed to stand for 0.5-2 hours before being vacuum sealed.

[0025] Traditional methods for preparing cement-based or concrete-based supercapacitors typically involve directly inserting electrodes into a prepared slurry and then curing it integrally, without the assembly process described in this invention. This integral molding approach presents several problems: firstly, the addition of electrolyte during slurry preparation severely hinders the cement hydration process, leading to strength loss; secondly, over time, water in the cement / concrete material evaporates and is lost, and the loss of water as an ion carrier significantly impacts ion migration.

[0026] In contrast, the assembly process employed in this application effectively avoids the aforementioned problems. In the assembly process provided by this invention, the alkali-activated concrete diaphragm and two electrodes are placed in an aluminum-plastic bag, and then an electrolyte is injected. After the electrolyte has fully wetted the diaphragm and electrodes, a vacuum negative pressure is used to force the electrolyte into the pores of the diaphragm, followed by sealing with a thermoforming machine. This ensures close contact between the electrodes and the diaphragm while preventing moisture evaporation.

[0027] The third objective of this invention is to provide the application of the alkali-activated concrete-based supercapacitor described in one of the objectives of this invention in the preparation of building or infrastructure components that have both structural load-bearing function and electrochemical energy storage function.

[0028] Furthermore, the alkali-activated concrete-based supercapacitor is applied to the supporting structure of photovoltaic roofs, thermal power building walls, wind turbine foundations, plywood floor paving layers, or self-powered wireless sensor networks. These energy harvesting facilities typically require corresponding energy storage devices (batteries or supercapacitors). However, the deployment of commercial energy storage devices faces significant challenges: on the one hand, construction requires consideration of safe buffer distances from surrounding communities and occupies additional land, resulting in high costs; on the other hand, large-scale applications pose safety hazards such as short circuits, thermal runaway, gas leaks, and even explosions, posing serious threats to public safety and the urban environment.

[0029] The alkali-activated concrete-based supercapacitor provided by this invention overcomes geographical limitations and reduces construction costs. It does not occupy additional physical space but instead endows existing structural components with energy storage functions, achieving deep coupling of energy capture, storage, and utilization. Furthermore, the alkali-activated concrete supercapacitor is inherently compatible with building structures at the material level and can be directly embedded into energy harvesting equipment for integrated use, achieving a perfect balance between load-bearing capacity and energy storage. Its flame-retardant and explosion-proof properties fundamentally eliminate safety hazards.

[0030] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The present invention provides an alkali-activated concrete-based supercapacitor, comprising an alkali-activated concrete-based diaphragm. The alkali-activated concrete-based diaphragm is prepared by discontinuous gradation of alkali-activated slurry and small-diameter coarse aggregate. The preparation process is simple and low-cost. The diaphragm prepared by this method has controllable macroscopic interconnected pores, providing a convenient flow path for the electrolyte. It also forms a multi-scale pore network with the gel pores and capillaries in the alkali-activated slurry, providing abundant and stable channels for ion transport. Furthermore, the alkali-activated slurry has high strength and plastic viscosity, enabling it to efficiently encapsulate the coarse aggregate, ensuring continuous load transfer and providing core strength support for the alkali-activated concrete-based diaphragm.

[0031] (2) The present invention provides an alkali-activated concrete-based supercapacitor, which realizes the first application on the concrete scale. It also has excellent mechanical and electrochemical properties and is expected to be applied on a large scale in actual building structures, promoting the sustainable development of smart cities. Attached Figure Description

[0032] Figure 1 A schematic diagram of the structure of an alkali-activated concrete-based supercapacitor provided in an embodiment of the present invention; Figure 2 This is a gel pore-capillary distribution diagram obtained by nitrogen adsorption test of the alkali-activated concrete-based diaphragm in the supercapacitor prepared in Example 2 of the present invention. Figure 3 The image shows the distribution of capillary and macropores in the alkali-activated concrete-based diaphragm of the supercapacitor prepared in Example 2 of the present invention, obtained by mercury intrusion porosimetry. Figure 4 The image shows a three-dimensional reconstruction of the macroscopic pores obtained by X-ray computed tomography of the alkali-excited concrete-based diaphragm in the supercapacitor prepared in Example 2 of the present invention. Figure 5 Cyclic voltammetry of an alkali-excited concrete-based supercapacitor; Figure 6 Constant current charge-discharge diagram for alkali-excited concrete-based supercapacitor; Figure 7 Cycle / efficiency diagram for alkali-excited concrete-based supercapacitors. Detailed Implementation

[0033] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] This invention provides an alkali-activated concrete-based supercapacitor and its assembly method. The assembly method includes the following steps: placing an alkali-activated concrete-based diaphragm between the positive and negative electrodes, loading the whole unit into a flexible packaging shell made of aluminum-plastic film, injecting electrolyte, letting it stand for 0.5-2 hours, and then vacuum sealing to obtain the supercapacitor.

[0035] The electrode comprises one of the following: activated carbon electrode-activated carbon electrode combination, manganese dioxide electrode-activated carbon electrode combination, graphene electrode-graphene electrode combination, and manganese dioxide electrode-graphene electrode combination. The electrolyte is a NaOH, KOH, Na2SO4, or K2SO4 solution with a concentration of 2-10 mol / L.

[0036] The raw material composition of the alkali-activated concrete-based diaphragm, by weight, includes: 160-180 parts of fly ash and / or metakaolin; 160-180 parts of mineral powder; 1400-2100 parts of aggregate, wherein the aggregate has a particle size of 3-5 mm; 13-17 parts of sodium hydroxide or potassium hydroxide; and 120-130 parts of sodium silicate or potassium silicate.

[0037] The method for preparing the alkali-activated concrete-based diaphragm includes the following steps: Step 1: Mix water, sodium hydroxide or potassium hydroxide evenly to form a sodium hydroxide solution or potassium hydroxide solution, then add it to a sodium silicate solution or potassium silicate solution and mix evenly to prepare an alkaline activator solution for later use; Step 2: Add fly ash or metakaolin, mineral powder and limestone aggregate to the mixer and mix for 2-3 minutes. Then add alkali activator and continue mixing for 2-3 minutes. Pour into the mold and manually tamp in three layers. After hardening and shaping, demold and cure at 20-30℃ and 90%-95% relative humidity. Step 3: Cut the alkali-activated concrete that has been cured for 28 days into pieces of 50×60×10 mm, put them into an ultrasonic cleaner for 4-6 minutes to remove residue, and obtain alkali-activated concrete slices. Step 4: Place the cleaned alkali-activated concrete slices into a vacuum drying oven and dry them at 50-70℃ for 12-48 hours to remove moisture; Step 5: Place the alkali-activated concrete slices in the electrolyte and immerse them under vacuum for 6-9 hours to obtain the alkali-activated concrete base membrane.

[0038] The present invention will be further described below with reference to specific embodiments, but these are not intended to limit the scope of the invention.

[0039] Example 1 This embodiment provides an alkali-activated concrete-based supercapacitor, the schematic diagram of which is shown below. Figure 1 As shown, the preparation steps include the following: (1) Preparation of alkali-activated concrete-based diaphragm: Weigh 37g of water and 13g of sodium hydroxide, mix them evenly, add 120g of sodium silicate and continue stirring to form an alkali activator for later use. Weigh 165g of fly ash, 165g of mineral powder, and 1400g of limestone aggregate, place them in a mixer and mix for 2 min. Add the alkali activator and continue stirring for 2 min. Pour the mixture into a 100×100×100 mm mold, manually tamp it in three layers, and demold it after hardening and molding. Cure it in a standard curing room (25℃, relative humidity 90%) for 28 days. After reaching the curing age, cut the alkali-activated concrete into 50×60×10 mm sheet diaphragms, then put them into an ultrasonic cleaner for 5 min. Place the cleaned alkali-activated concrete slices into a vacuum drying oven and dry them at 60℃ for 24 h. Immerse the dried alkali-activated concrete slices in a 6 mol / L sodium hydroxide solution and soak them under vacuum for 12 h to obtain the alkali-activated concrete-based diaphragm.

[0040] (2) Preparation of activated carbon electrode: 16g of activated carbon powder and 2g of conductive carbon black were mixed and ground, then 2g of polytetrafluoroethylene emulsion and 40 mL of anhydrous ethanol were added. The mixture was stirred thoroughly with a magnetic stirrer for 6 hours. After the ethanol evaporated, a viscous agglomerate was obtained. The agglomerate was coated onto the nickel foam current collector and then pressed into tablets using a tablet press (loading amount of 10 mg / cm). 2 The activated carbon electrodes were dried in a vacuum drying oven at 65℃ for 6 hours and then cut into 40×50 mm pieces.

[0041] (3) Assembly of alkali-activated concrete-based supercapacitor: The alkali-activated concrete-based diaphragm is sandwiched between two activated carbon electrodes and placed in a 100×100 mm aluminum foil soft bag. 10 mL of 6mol / L sodium hydroxide electrolyte is injected into the bag. After standing for 1 hour, vacuum is applied and the bag is sealed to obtain the alkali-activated concrete-based supercapacitor.

[0042] Example 2 This embodiment provides an alkali-activated concrete-based supercapacitor, the schematic diagram of which is shown below. Figure 1 As shown, the preparation steps include the following: (1) Preparation of alkali-activated concrete-based diaphragm: Weigh 37g of water and 13g of sodium hydroxide, mix them evenly, add 120g of sodium silicate and continue stirring to form an alkali activator for later use. Weigh 175g of fly ash, 175g of mineral powder and 1750g of limestone aggregate, put them in a mixer and mix for 2 min. Add the alkali activator and continue stirring for 2 min. Put them into a 100×100×100 mm mold, tamp them manually in three layers, and demold them after hardening and molding. Cure them in a standard curing room (25℃, relative humidity 90%) for 28 days. After reaching the curing age, cut the alkali-activated concrete into 50×60×10 mm sheet diaphragms, and then put them into an ultrasonic cleaner for 5 min. Put the cleaned alkali-activated concrete slices into a vacuum drying oven and dry them at 60℃ for 24 h. Soak the dried alkali-activated concrete slices in a 6 mol / L sodium hydroxide solution and immerse them in a vacuum for 12 h to obtain the alkali-activated concrete-based diaphragm.

[0043] (2) Preparation of activated carbon electrode: 16g of activated carbon powder and 2g of conductive carbon black were mixed and ground, then 2g of polytetrafluoroethylene emulsion and 40 mL of anhydrous ethanol were added. The mixture was stirred thoroughly with a magnetic stirrer for 6 hours. After the ethanol evaporated, a viscous agglomerate was obtained. The agglomerate was coated onto the nickel foam current collector and then pressed into tablets using a tablet press (loading amount of 10 mg / cm). 2 The activated carbon electrodes were dried in a vacuum drying oven at 65℃ for 6 hours and then cut into 40×50 mm pieces.

[0044] (3) Preparation of alkali-activated concrete-based supercapacitor: The alkali-activated concrete-based diaphragm is sandwiched between two activated carbon electrodes and placed in a 100×100 mm aluminum foil soft bag. 10 mL of 6mol / L sodium hydroxide electrolyte is injected into the bag. After standing for 1 hour, vacuum is applied and the bag is sealed to obtain the alkali-activated concrete-based supercapacitor.

[0045] Figure 2 The image shows the gel pore-capillary distribution of the alkali-activated concrete-based diaphragm obtained by nitrogen adsorption testing, indicating that its micropore size is mainly concentrated below 50 nm. Figure 3 The image shows the distribution of capillary and macropores in the alkali-activated concrete-based diaphragm obtained by mercury intrusion porosimetry. The results indicate that the proportions of capillary and macropores are 28% and 9.3%, respectively, which confirms the existence of a gel pore-capillary-macropore network inside the alkali-activated slurry.

[0046] Figure 4 This is an X-ray computed tomography (CT) image of the alkali-activated concrete-based diaphragm prepared in Example 2. Figure 4It can be seen that the alkali-activated concrete-based diaphragm has millimeter-scale macroscopic pores distributed in it. As a channel network for electrolyte storage and rapid ion transport, it can effectively reduce ion migration resistance and improve the uniformity of electrolyte wetting inside the diaphragm, thereby significantly enhancing the overall electrochemical performance of the supercapacitor.

[0047] Depend on Figure 2-4 It is known that the alkali-activated concrete-based diaphragm prepared by the present invention has a multi-scale pore network of gel pores, capillaries, macropores and macropores, which provides an efficient channel for ion transport, and thus can provide supercapacitors with electrochemical performance comparable to that of conventional supercapacitors using commercial diaphragms.

[0048] Example 3 This embodiment provides an alkali-activated concrete-based supercapacitor, the schematic diagram of which is shown below. Figure 1 As shown, the preparation steps include the following: (1) Preparation of alkali-activated concrete-based diaphragm: Weigh 37g of water and 13g of sodium hydroxide, mix them evenly, add 120g of sodium silicate and continue stirring to form an alkali activator for later use. Weigh 180g of fly ash, 180g of mineral powder, and 2100g of limestone aggregate, place them in a mixer and mix for 2 min. Add the alkali activator and continue stirring for 2 min. Pour the mixture into a 100×100×100 mm mold, manually tamp it in three layers, and demold it after hardening and molding. Cure it in a standard curing room (25℃, relative humidity 90%) for 28 days. After reaching the curing age, cut the alkali-activated concrete into 50×60×10 mm sheet diaphragms, and then put them into an ultrasonic cleaner for 5 min. Put the cleaned alkali-activated concrete slices into a vacuum drying oven and dry them at 60℃ for 24 h. Soak the dried alkali-activated concrete slices in a 6 mol / L sodium hydroxide solution and impregnate them under vacuum for 12 h to obtain the alkali-activated concrete-based diaphragm.

[0049] (2) Preparation of activated carbon electrode: 16g of activated carbon powder and 2g of conductive carbon black were mixed and ground, then 2g of polytetrafluoroethylene emulsion and 40 mL of anhydrous ethanol were added. The mixture was stirred thoroughly with a magnetic stirrer for 6 hours. After the ethanol evaporated, a viscous agglomerate was obtained. The agglomerate was coated onto the nickel foam current collector and then pressed into tablets using a tablet press (loading amount of 10 mg / cm). 2 The activated carbon electrodes were dried in a vacuum drying oven at 65℃ for 6 hours and then cut into 40×50 mm pieces.

[0050] (3) Preparation of alkali-activated concrete-based supercapacitor: The alkali-activated concrete-based diaphragm is sandwiched between two activated carbon electrodes and placed in a 100×100 mm aluminum foil soft bag. 10 mL of 6mol / L sodium hydroxide electrolyte is injected into the bag. After standing for 1 hour, vacuum is applied and the bag is sealed to obtain the alkali-activated concrete-based supercapacitor.

[0051] Example 4 This embodiment provides an alkali-activated concrete-based supercapacitor, comprising the following preparation steps: (1) Preparation of alkali-activated concrete-based diaphragm: Weigh 37g of water and 13g of potassium hydroxide, mix them evenly, add 120g of potassium silicate and continue stirring to form an alkali activator for later use. Weigh 175g of metakaolin, 175g of mineral powder and 1750g of limestone aggregate, put them in a mixer and mix for 2 min. Add the alkali activator and continue stirring for 2 min. Put them into a 100×100×100 mm mold, manually tamp them in three layers, and demold them after hardening and molding. Cure them in a standard curing room (25℃, relative humidity 90%) for 28 days. After reaching the curing age, cut the alkali-activated concrete into 50×60×10 mm sheet diaphragms, and then put them into an ultrasonic cleaner for 5 min. Put the cleaned alkali-activated concrete slices into a vacuum drying oven and dry them at 60℃ for 24 h. Soak the dried alkali-activated concrete slices in a 6 mol / L potassium hydroxide solution and immerse them in a vacuum for 12 h to obtain the alkali-activated concrete-based diaphragm.

[0052] (2) Electrode preparation: 16g of activated carbon powder or manganese dioxide powder was mixed and ground with 2g of conductive carbon black, then 2g of polytetrafluoroethylene emulsion and 40 mL of anhydrous ethanol were added. The mixture was stirred thoroughly with a magnetic stirrer for 6 hours. After the ethanol evaporated, a viscous agglomerate was obtained. The agglomerate was coated onto the nickel foam current collector and then pressed into tablets using a tablet press (loading amount of 10 mg / cm). 2 The electrodes were dried in a vacuum drying oven at 65℃ for 6 hours, and then cut into 40×50 mm activated carbon electrodes or manganese dioxide electrodes.

[0053] (3) Preparation of alkali-activated concrete-based supercapacitor: The alkali-activated concrete-based diaphragm is sandwiched between the manganese dioxide positive electrode and the activated carbon negative electrode, and placed in a 100×100 mm aluminum foil soft bag. 10 mL of 6mol / L potassium hydroxide electrolyte is injected into the bag. After standing for 1 hour, vacuum is drawn and the bag is sealed to obtain the alkali-activated concrete-based supercapacitor.

[0054] Application performance testing The alkali-activated concrete-based supercapacitors prepared in Examples 1-3 were subjected to application performance tests, including electrochemical performance (surface capacitance, cycle retention, and coulombic efficiency) and mechanical performance (compressive strength). Relevant test figures are shown below. Figure 5-7 As shown in Table 1 below, the test results are as follows.

[0055] Table 1

[0056] Depend on Figure 5It can be seen that the cyclic voltammetry curves of Examples 1-3 at a scan rate of 5 mV / s are quasi-rectangular and have no redox peaks, exhibiting typical double-layer capacitance characteristics. Figure 6 It can be seen that Examples 1-3 are at 1 mA / cm 2 The charge-discharge curve at the current density is an isosceles triangle with a small voltage drop, indicating good reversibility. Figure 7 It can be seen that Examples 1-3 are at 1 mA / cm 2 After 1000 cycles at current density, the capacity retention reaches 80.52%, and the coulombic efficiency is almost 100%.

[0057] Furthermore, according to the application performance test results shown in Table 1, the surface capacitance of the alkali-activated concrete-based supercapacitors prepared in Examples 1-3 reaches 360-630 mF / cm². 2 The compressive strength reached 24.5-38.5 MPa, exhibiting excellent electrochemical and mechanical properties. Compared with Examples 1 and 3, Example 2 achieved the best overall performance by optimizing the proportion of mineral powder and aggregate in the alkali-activated concrete raw materials.

[0058] In summary, the alkali-activated concrete-based supercapacitor provided by this invention achieves significant breakthroughs in three aspects: application scenarios, mechanical properties, and electrochemical performance. In terms of application, it solves the problems of high brittleness, poor durability, and high cost associated with traditional cement-based materials, enabling concrete-scale manufacturing with a simple and low-cost process, allowing for direct embedding into building structures for large-scale application. Regarding mechanical properties, it overcomes the limitations of traditional cement-based supercapacitors, such as low compressive strength and inability to bear loads, possessing high compressive strength and simultaneously fulfilling both energy storage and load-bearing functions. In terms of electrochemical performance, by constructing a continuous pore structure from microscopic to macroscopic levels, the ion transport rate is significantly improved, resulting in superior electrochemical performance. It has significant application potential in the preparation of buildings or components that combine structural load-bearing and electrochemical energy storage functions.

[0059] The above are merely preferred embodiments of the present invention and are not intended to limit the implementation methods and protection scope of the present invention. Those skilled in the art should recognize that any equivalent substitutions and obvious changes made based on the content of this specification should be included within the protection scope of the present invention.

Claims

1. An alkali-activated concrete-based supercapacitor, characterized by, The supercapacitor comprises a positive electrode, a negative electrode, a diaphragm and an electrolyte. The diaphragm is an alkali-activated concrete-based diaphragm, and the raw material composition of the alkali-activated concrete-based diaphragm comprises, by weight: fly ash and / or metakaolin 160-180 parts; mineral powder 160-180 parts; aggregate 1400-2100 parts, the particle size of the aggregate being 3-5 mm; alkali activator 133-147 parts; water 37-43 parts.

2. The alkali-activated concrete-based ultracapacitor of claim 1, wherein, The aggregate comprises a combination of one or more of limestone, basalt and granite.

3. The alkali-activated concrete-based ultracapacitor of claim 1, wherein, The alkali activator comprises 13-17 parts by weight of sodium hydroxide or potassium hydroxide and 120-130 parts by weight of sodium silicate or potassium silicate.

4. The alkali-activated concrete-based ultracapacitor of claim 1, wherein, The preparation method of the alkali-activated concrete-based diaphragm comprises the following steps: S1, preparing an alkali activator solution by mixing water and an alkali activator; S2, mixing fly ash and / or metakaolin, mineral powder and aggregate, adding the alkali activator solution and continuing to mix, then pouring into a mold, layering, vibrating and compacting, hardening and shaping, demolding and curing; S3, after curing, the obtained alkali-activated concrete is cut, washed and dried, then immersed in an electrolyte under vacuum to obtain an alkali-activated concrete-based diaphragm.

5. The alkali-activated concrete-based ultracapacitor of claim 4, wherein, In step S2, the fly ash and / or metakaolin, mineral powder and aggregate are mixed for 2-3 min, the alkali activator solution is added and mixed for 2-3 min, and layering, vibrating and compacting are performed by artificial insertion in three layers.

6. The alkali-activated concrete-based ultracapacitor of claim 4, wherein, In step S3, the curing temperature is 20-30℃, the relative humidity is 90%-95%, and the curing time is 28 days; the immersion time is 6-9 h.

7. The alkali-activated concrete-based ultracapacitor of claim 1, wherein, The positive electrode and the negative electrode are each selected from one of activated carbon electrodes, manganese dioxide electrodes and graphene electrodes, and the materials of the positive electrode and the negative electrode are the same or different.

8. The alkali-activated concrete-based ultracapacitor of claim 1, wherein, The electrolyte is a NaOH, KOH, Na2SO4 or K2SO4 solution with a concentration of 2-10 mol / L, and the supercapacitor is soft-packaged with an aluminum plastic film.

9. The method of assembling an alkali-activated concrete-based supercapacitor according to any one of claims 1-8, wherein, The alkali-activated concrete-based diaphragm is placed between the positive electrode and the negative electrode, the whole is loaded into a flexible packaging shell made of an aluminum plastic film, an electrolyte is injected, vacuum packaging is performed, and a supercapacitor is obtained.

10. Use of the alkali-activated concrete-based supercapacitor according to any one of claims 1-8 in the preparation of a building or infrastructure component having both structural load-bearing function and electrochemical energy storage function.

Images