Copper ion-based cement-based supercapacitor and method of making same

Abstract

The application relates to the field of civil engineering materials and energy storage technology, in particular to a cement-based super capacitor based on copper ions and a preparation method thereof. The cement-based super capacitor comprises an electrode layer and a cement-based functional layer arranged between the electrode layer; raw materials of the cement-based functional layer comprise cement, carbon black, anionic polyacrylamide, copper sulfate, water and a water reducing agent. By introducing the synergistic mechanism of copper ions and anionic polyacrylamide, the carbon black content, the water-binder ratio and the proportion of functional components are optimized, the structural integrity of the cement matrix is maintained while the continuity of the conductive network is ensured, the synergistic improvement of the electrochemical performance and the mechanical performance is realized, the specific capacitance of the prepared cement-based super capacitor can reach >= 80 F / g, the energy density can be >= 5 Wh / kg, the capacity retention rate is still >= 80% after >= 10000 charge-discharge cycles, the compressive strength can be stably >= 30 MPa, and the volume resistivity is <= 10 3 Ω*cm.

Description

Technical Field

[0001] This invention relates to the fields of civil engineering materials and energy storage technology, specifically to a copper ion-based cement-based supercapacitor and its preparation method. Background Technology

[0002] With the large-scale application of intermittent renewable energy sources such as wind and solar power, the mismatch between energy supply and demand over time is becoming increasingly prominent, placing higher demands on efficient and large-scale energy storage technologies. While traditional lithium-ion batteries possess high energy density, they are limited by factors such as raw material resources, cost, environmental impact, and the need for dedicated space, making it difficult to meet the demand for low-cost, environmentally friendly energy storage that can be integrated with infrastructure. Supercapacitors, with their advantages of high power density, fast charging and discharging speeds, and long cycle life, are an important supplement to renewable energy storage. However, existing supercapacitors mostly employ organic electrolytes and complex layered structures, resulting in high manufacturing costs and complex structures, which are not conducive to integrated applications with building structures and other engineering scenarios.

[0003] Cement-based materials, as the most widely used building materials globally, are characterized by their wide availability, low cost, and good durability, and have been considered to have the potential to construct structural energy storage devices in recent years. By introducing conductive fillers such as carbon black, cement-based composite materials can form a porous structure after curing, providing channels for electrolyte wetting and ion transport, thus providing a material basis for the development of cement-based supercapacitors. Supercapacitor structures based on cement-based materials have been reported. For example, Chinese patent CN117976422A discloses a cement-based carbon black supercapacitor, in which the electrolyte and electrodes are made of cement-based carbon black materials, and the separator is a polypropylene modified separator. However, the final capacitor has limited charge storage capacity and a low overall energy density. Chinese patent CN119495513B discloses a cement-based zinc ion hybrid capacitor and its preparation method, which introduces composite entraining gas into the cement-based energy storage device, improving the ionic conductivity of the cement-based structural electrolyte and significantly improving the energy storage performance. However, the excessive porosity inevitably weakens the compactness of the cement matrix and the continuity of the load-bearing skeleton, making it difficult to meet the load-bearing requirements of reagent engineering structural components. Summary of the Invention

[0004] To address the technical problems of existing cement-based supercapacitors, such as the difficulty in achieving synergistic electrochemical and mechanical properties, complex preparation processes, and limited applications, this invention provides a copper-ion-based cement-based supercapacitor and its preparation method.

[0005] The specific technical solution is as follows:

[0006] In a first aspect, the present invention provides a copper ion-based cement-based supercapacitor, comprising an electrode layer and a cement-based functional layer disposed between the electrode layers; the raw materials of the cement-based functional layer include cement, carbon black, anionic polyacrylamide, copper sulfate, water, and a water-reducing agent; the water-binder ratio of the cement-based functional layer is 0.45~0.55, the amount of carbon black is 1%~3% of the cement mass, the amount of anionic polyacrylamide is 0.1%~0.5% of the cement mass, the amount of copper sulfate is 0.1%~2% of the cement mass, and the amount of water-reducing agent is 0.05%~0.3% of the cement mass.

[0007] This cement-based supercapacitor combines structural load-bearing and energy storage functions, achieving an integrated structure-energy storage design. This reduces the need for separate diaphragms or energy storage units, improving space utilization. In the raw materials of the cement-based functional layer, carbon black is used to construct a continuous electronic conductive network; copper sulfate provides copper ions to improve the ionic conductivity of the pore solution and reduce interfacial charge transfer resistance; anionic polyacrylamide improves the stability of copper ions and the dispersibility of carbon black, enhancing ion migration efficiency; and a water-reducing agent improves the fluidity and density of the slurry while controlling the water-cement ratio. By using the appropriate dosage ranges of these raw materials, the cement-based supercapacitor can achieve both strong conductivity and compressive strength, realizing synergistic optimization of electrochemical and mechanical properties.

[0008] Furthermore, the electrode layer is a composite electrode with a nickel foam-supported activated carbon slurry coating. The raw materials for the activated carbon slurry coating include activated carbon, conductive carbon black, polyvinylidene fluoride (PVDF), and N-methylpyrrolidone. Nickel foam provides a three-dimensional porous conductive framework structure, activated carbon provides high specific surface area energy storage sites, conductive carbon black enhances electron transport capability, PVDF acts as a binder to improve electrode structural stability, and N-methylpyrrolidone ensures uniform dispersion of the slurry, thereby improving overall capacitance performance and cycle stability.

[0009] Furthermore, the mass ratio of activated carbon, conductive carbon black, and polyvinylidene fluoride is 7~9:0.5~1.5:0.5~1.5. This ratio range can maintain the mechanical strength and conductive continuity of the electrode while ensuring a high specific capacitance, and avoid the reduction of active sites due to excessive binder or the structural detachment due to insufficient binder.

[0010] Furthermore, the thickness of the activated carbon slurry coating is 100~200μm, which ensures sufficient energy storage active material quality while avoiding excessively long ion diffusion paths that could affect rate performance.

[0011] Furthermore, the cement-based functional layer raw material also includes nanocellulose, with the nanocellulose content being 0.05% to 0.3% of the cement mass. Nanocellulose forms a micro-reinforcing network structure in the cement matrix, which can improve compressive strength and inhibit microcrack propagation, while also improving slurry uniformity and structural stability.

[0012] Secondly, the present invention provides a method for preparing the above-mentioned cement-based supercapacitor, comprising the following steps:

[0013] (1) Electrode preparation: The nickel foam was cut and ultrasonically cleaned with ethanol and deionized water and then dried; activated carbon, conductive carbon black, polyvinylidene fluoride and N-methylpyrrolidone were mixed to prepare activated carbon slurry, which was coated on the surface of the nickel foam and vacuum dried to obtain a composite electrode of nickel foam loaded with activated carbon.

[0014] (2) Preparation of cement-based slurry: Weigh all raw materials according to the proportion. First, mix cement and carbon black and stir to obtain dry material. Mix anionic polyacrylamide with water and water-reducing agent evenly, pour into dry material, and wet mix until evenly mixed to obtain wet material. Pour copper sulfate solution into wet material and stir evenly to obtain cement-based slurry.

[0015] (3) Molding and curing: Cement-based slurry is poured into the mold and composite electrodes are inserted. After vibration molding, it is left to stand at room temperature. After demolding, it is transferred to a standard curing box for curing to obtain cement-based supercapacitor.

[0016] In the above preparation method, the dry mixing step is conducive to the uniform dispersion of carbon black, the wet mixing process enhances the uniformity of the system, and the subsequent addition of copper sulfate solution can avoid the local high concentration of copper ions affecting the hydration process, while ensuring uniform ion distribution, thereby improving electrochemical performance.

[0017] Furthermore, the dry mixing time in step (2) is 1~4 min, and the wet mixing time is 2~6 min.

[0018] Furthermore, the concentration of the copper sulfate solution in step (2) is 0.1~0.5 mol / L.

[0019] Furthermore, in step (3), vibration molding is performed using a 50Hz vibration table. After the air bubbles are expelled, the material is naturally vibrated for 2-5 minutes. The composite electrode insertion position is fixed by a partition. The static time is 18-36 hours, and the curing time is 3-28 days. Vibration molding can improve density and reduce pore defects. Sufficient curing is conducive to the completion of cement hydration reaction, thereby improving compressive strength and structural stability.

[0020] Thirdly, the present invention also provides a method for preparing the above-mentioned cement-based supercapacitor, comprising the following steps:

[0021] (1) Electrode preparation: The nickel foam was cut and ultrasonically cleaned with ethanol and deionized water and then dried; activated carbon, conductive carbon black, polyvinylidene fluoride and N-methylpyrrolidone were mixed to prepare activated carbon slurry, which was coated on the surface of the nickel foam and vacuum dried to obtain a composite electrode of nickel foam loaded with activated carbon.

[0022] (2) Preparation of cement-based slurry: Weigh various raw materials according to the proportion, mix cement and carbon black first and stir to obtain dry material; add nanocellulose to water in advance, and disperse it by high-speed shearing or ultrasonic treatment to obtain nanocellulose dispersion; add anionic polyacrylamide and water-reducing agent to nanocellulose dispersion, mix evenly and pour into dry material, and wet mix until evenly mixed to obtain wet material; pour copper sulfate solution into wet material and stir evenly to obtain cement-based slurry;

[0023] (3) Molding and curing: Cement-based slurry is poured into the mold and composite electrodes are inserted. After vibration molding, it is left to stand at room temperature. After demolding, it is transferred to a standard curing box for curing to obtain cement-based supercapacitor.

[0024] In this preparation method, the pre-dispersion treatment can avoid the agglomeration of nanocellulose, improve the uniformity of the reinforcing effect, and further improve the mechanical properties and durability of the cement matrix.

[0025] The beneficial effects of this invention are as follows:

[0026] 1. This invention provides a copper-ion-based cement-based supercapacitor and its preparation method. By introducing a synergistic mechanism between copper ions and anionic polyacrylamide, the cement-based energy storage system is optimized from the perspectives of ion transport and interfacial charge regulation. During cement hydration, copper ions form a stable system with anionic polyacrylamide, which helps to uniformly disperse the conductive phase, reduces agglomeration, constructs a continuous and stable charge transport network, reduces the internal resistance of the material, and improves ion migration efficiency. Testing shows that the cement-based supercapacitor prepared by this invention has a specific capacitance of ≥80 F / g and an energy density of ≥5 Wh / kg, significantly better than conventional cement-based energy storage materials (specific capacitance is typically below 50 F / g, and energy density is below 2 Wh / kg). Furthermore, after ≥10,000 charge-discharge cycles, the capacity retention rate remains ≥80%, demonstrating excellent cycle stability.

[0027] 2. This invention optimizes the carbon black content, water-cement ratio, and functional component proportions to maintain the structural integrity of the cement matrix while ensuring the continuity of the conductive network, achieving a synergistic improvement in electrochemical and mechanical properties. The resulting material exhibits a stable compressive strength ≥30MPa and a volume resistivity ≤10. 3 With a strength of Ω·cm, it not only meets the basic load-bearing requirements of building structural materials but also possesses excellent energy storage capabilities, enabling integrated design of structure and energy storage.

[0028] 3. The preparation process provided by this invention is compatible with conventional concrete construction procedures and can be directly applied to existing mixing, pouring, and curing processes without the need for additional independent energy storage devices or specialized construction equipment. This helps reduce construction costs and improve project applicability. Furthermore, the carbon black used in this invention can be obtained from industrial solid wastes such as fly ash, slag, and steel slag through modification treatment. After treatment, it is used to construct a conductive network, achieving resource utilization of solid waste while ensuring energy storage performance, which helps reduce material costs and environmental burden. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a constant current charge-discharge curve diagram of Embodiment 1 of this application.

[0031] Figure 2 This is a cyclic voltammetry test curve of Embodiment 1 of this application.

[0032] Figure 3 These are test results of the compressive strength of Examples 1-4 and Comparative Example 1 after different curing times.

[0033] Figure 4 These are the resistivity test results of Examples 1-4 of this application after different curing times.

[0034] Figure 5 These are the cycle performance test results of embodiments 1-4 of this application. Detailed Implementation

[0035] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0036] Example 1: A Cement-Based Supercapacitor Based on Copper Ions

[0037] (1) Electrode preparation: Cut the nickel foam to a size of 40mm×20mm×1mm, ultrasonically clean it with ethanol and deionized water for 15min, and dry it at 60℃ for 2 hours; weigh 8g of activated carbon, 1g of conductive carbon black and 1g of PVDF in a mass ratio of 8:1:1, add 20mL of N-methylpyrrolidone, and magnetically stir for 2 hours to prepare activated carbon slurry; coat the activated carbon slurry onto the surface of the nickel foam with a coating thickness of 150μm, air dry it naturally for 30min, and then vacuum dry it at 80℃ for 12h.

[0038] (2) Preparation of cement-based slurry: First, mix 450g of cement and 9g of carbon black and stir for 2min to obtain dry material; mix 0.9g of anionic polyacrylamide with 225g of water and 0.45g of water-reducing agent evenly, pour into dry material, and wet mix for 2min to obtain wet material; pour 45mL of 0.3mol / L copper sulfate solution (copper sulfate dosage is 0.3% of cement mass) into wet material and stir for 2min to obtain cement-based slurry.

[0039] (3) Molding and curing: Pour cement-based slurry into a 30mm×30mm×30mm custom mold and insert the prepared electrode. Vibrate the mold on a 50Hz vibration table, vibrate naturally for 3 minutes, and let it stand at room temperature for 24 hours before demolding. Transfer it to a standard curing box with a temperature of 20±2℃ and relative humidity ≥95% for 28 days to obtain a copper ion-based cement-based supercapacitor.

[0040] Example 2: A Cement-Based Supercapacitor Based on Copper Ions

[0041] The difference from Example 1 is that the proportions of each raw material in Example 2 are as follows: 450g cement, 4.5g carbon black, 0.45g anionic polyacrylamide, 225g water, 0.45g water-reducing agent, and 45mL of 0.1mol / L copper sulfate solution (the amount of copper sulfate is 0.1% of the cement mass). Other treatments are the same as in Example 1.

[0042] Example 3: A Cement-Based Supercapacitor Based on Copper Ions

[0043] The difference from Example 1 is that the proportions of each raw material in Example 3 are as follows: 450g cement, 13.5g carbon black, 2.25g anionic polyacrylamide, 225g water, 0.45g water-reducing agent, and 45mL of 0.5mol / L copper sulfate solution (the amount of copper sulfate is 0.5% of the cement mass). Other treatments are the same as in Example 1.

[0044] Comparative Example 1

[0045] The difference from Example 1 is that the cement slurry in Comparative Example 1 was prepared by mixing 450g of cement, 225g of water, and 0.45g of water-reducing agent and stirring evenly to obtain the cement slurry. Other processing steps were the same as in Example 1.

[0046] Example 4: Cement-based supercapacitor with added nanocellulose

[0047] (1) Electrode preparation: Cut the nickel foam to a size of 40mm×20mm×1mm, ultrasonically clean it with ethanol and deionized water for 15min, and dry it at 60℃ for 2 hours; weigh 8g of activated carbon, 1g of conductive carbon black and 1g of PVDF in a mass ratio of 8:1:1, add 20mL of N-methylpyrrolidone, and magnetically stir for 2 hours to prepare activated carbon slurry; coat the activated carbon slurry onto the surface of the nickel foam with a coating thickness of 150μm, air dry it naturally for 30min, and then vacuum dry it at 80℃ for 12h.

[0048] (2) Preparation of cement-based slurry: First, mix 450g of cement and 9g of carbon black and stir for 2min to obtain dry material; add 0.45g of nanocellulose to 225g of water and disperse it by ultrasonic treatment to obtain nanocellulose dispersion; add 0.9g of anionic polyacrylamide and 0.45g of water-reducing agent to nanocellulose dispersion, mix evenly and pour into dry material, mix until evenly mixed to obtain wet material; pour 45mL of 0.3mol / L copper sulfate solution (copper sulfate dosage is 0.3% of cement mass) into wet material and stir for 2min to obtain cement-based slurry.

[0049] (3) Molding and curing: Pour cement-based slurry into a 30mm×30mm×30mm custom mold and insert the prepared electrode. Vibrate the mold on a 50Hz vibration table, vibrate naturally for 3 minutes, and let it stand at room temperature for 24 hours before demolding. Transfer it to a standard curing box for 28 days to obtain a copper ion-based cement-based supercapacitor.

[0050] Test case

[0051] 1. Following the "Electrochemical Testing Methods for Supercapacitor Performance Testing" (GB / T 36376-2018), the cement-based capacitor prepared in Example 1 was subjected to constant current charge-discharge and cyclic voltammetry tests. A three-electrode system was used, with a 6 mol / L KOH solution as the electrolyte. The scan rate was 5–100 mV / s, and the current density was 0.5–5 A / g. The test results are as follows: Figure 1 , Figure 2 As shown. Furthermore, the cement-based capacitor prepared in Example 1 was tested at -20°C and 60°C, respectively. The results showed that the capacitance retention rate was 82% at -20°C and it operated stably without leakage at 60°C.

[0052] 2. Referring to the "Test Method for Strength of Cement Mortar (ISO Method)" (GB / T 17671-1999), the compressive strength of the cement-based supercapacitors in Examples 1-4 and Comparative Example 1 after different curing times (3d, 7d, and 28d) was tested. The results are as follows: Figure 3 As shown in the figure, the compressive strength of cement-based supercapacitors gradually increases with curing time, and the compressive strength can stably reach ≥30MPa after 7 days of curing.

[0053] 3. Referring to the "Test Methods for Volume Resistivity and Surface Resistivity of Solid Dielectrics" (GB / T 1410-2006) and "GB / T 36376-2018", the electrical performance of the cement-based capacitors prepared in Examples 1-4 and Comparative Example 1 was tested. The test items included volume resistivity, specific capacitance, energy density, and capacitance retention after 10,000 charge-discharge cycles. The test results are shown in [Figure number missing]. Figure 4 , Figure 5 See Table 1.

[0054] Table 1 Electrical properties of cement-based capacitors in each group

[0055]

[0056] Although the present invention has been described in detail with reference to the accompanying drawings and preferred embodiments, the present invention is not limited thereto. Various equivalent modifications or substitutions can be made to the embodiments of the present invention by those skilled in the art without departing from the spirit and essence of the invention, and such modifications or substitutions should all be within the scope of the present invention. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should also be covered within the protection scope of the present invention.

Claims

1. A cement-based supercapacitor based on copper ions, characterized in that, The device includes an electrode layer and a cement-based functional layer disposed between the electrode layers. The raw materials of the cement-based functional layer include cement, carbon black, anionic polyacrylamide, copper sulfate, water, and a water-reducing agent. The water-cement ratio of the cement-based functional layer is 0.45~0.55, the amount of carbon black is 1%~3% of the cement mass, the amount of anionic polyacrylamide is 0.1%~0.5% of the cement mass, the amount of copper sulfate is 0.1%~2% of the cement mass, and the amount of water-reducing agent is 0.05%~0.3% of the cement mass.

2. The cement-based supercapacitor as described in claim 1, characterized in that, The electrode layer is a composite electrode with a nickel foam-supported activated carbon slurry coating. The raw materials for the activated carbon slurry coating include activated carbon, conductive carbon black, polyvinylidene fluoride, and N-methylpyrrolidone solvent.

3. The cement-based supercapacitor as described in claim 1, characterized in that, The mass ratio of activated carbon, conductive carbon black and polyvinylidene fluoride is 7~9:0.5~1.5:0.5~1.

5.

4. The cement-based supercapacitor as described in claim 2, characterized in that, The thickness of the activated carbon slurry coating is 100~200μm.

5. The cement-based supercapacitor as described in claim 2, characterized in that, The raw materials for the cement-based functional layer also include nanocellulose, with the amount of nanocellulose being 0.05% to 0.3% of the cement mass.

6. A method for preparing a cement-based supercapacitor as described in any one of claims 1-4, characterized in that, Includes the following steps: (1) Electrode preparation: The nickel foam was cut and ultrasonically cleaned with ethanol and deionized water and then dried; activated carbon, conductive carbon black, polyvinylidene fluoride and N-methylpyrrolidone were mixed to prepare activated carbon slurry, which was coated on the surface of the nickel foam and vacuum dried to obtain a composite electrode of nickel foam loaded with activated carbon. (2) Preparation of cement-based slurry: Weigh all raw materials according to the proportion. First, mix cement and carbon black and stir to obtain dry material. Mix anionic polyacrylamide with water and water-reducing agent evenly, pour into dry material, and wet mix until evenly mixed to obtain wet material. Pour copper sulfate solution into wet material and stir evenly to obtain cement-based slurry. (3) Molding and curing: Cement-based slurry is poured into the mold and composite electrodes are inserted. After vibration molding, it is left to stand at room temperature. After demolding, it is transferred to a standard curing box for curing to obtain cement-based supercapacitor.

7. The preparation method according to claim 6, characterized in that, In step (2), the mixing time after mixing cement and carbon black is 1~4 min, and the wet mixing time is 2~6 min.

8. The preparation method according to claim 6, characterized in that, The concentration of the copper sulfate solution in step (2) is 0.1~0.5 mol / L.

9. The preparation method according to claim 6, characterized in that, In step (3), a vibration table with a frequency of 50Hz is used for vibration molding. After the air bubbles are expelled, the mixture is naturally vibrated for 2 to 5 minutes. The insertion position of the composite electrode is fixed by a partition. The static time is 18 to 36 hours, and the curing time is 3 to 28 days.

10. A method for preparing a cement-based supercapacitor as described in claim 5, characterized in that, Includes the following steps: (1) Electrode preparation: The nickel foam was cut and ultrasonically cleaned with ethanol and deionized water and then dried; activated carbon, conductive carbon black, polyvinylidene fluoride and N-methylpyrrolidone were mixed to prepare activated carbon slurry, which was coated on the surface of the nickel foam and vacuum dried to obtain a composite electrode of nickel foam loaded with activated carbon. (2) Preparation of cement-based slurry: Weigh various raw materials according to the proportion, mix cement and carbon black first and stir to obtain dry material; add nanocellulose to water in advance, and disperse it by high-speed shearing or ultrasonic treatment to obtain nanocellulose dispersion; add anionic polyacrylamide and water-reducing agent to nanocellulose dispersion, mix evenly and pour into dry material, and wet mix until evenly mixed to obtain wet material; Pour copper sulfate solution into the wet material and stir evenly to obtain cement-based slurry; (3) Molding and curing: Cement-based slurry is poured into the mold and composite electrodes are inserted. After vibration molding, it is left to stand at room temperature. After demolding, it is transferred to a standard curing box for curing to obtain cement-based supercapacitor.

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