A composite solid-state structure capacitor based on in-situ polymerization and a preparation method thereof

Abstract

The application discloses a composite solid-state structure capacitor based on in-situ polymerization and a preparation method thereof, and belongs to the fields of building energy storage and electrochemistry, comprising two active carbon-based electrodes and a cement-based solid-state electrolyte arranged between the two active carbon-based electrodes, wherein the active carbon-based electrode is made of foamed nickel, an active material, a conductive agent, a binder and an organic solvent; and the cement-based solid-state electrolyte is made of polyethylene glycol, acrylic acid, NaOH, a crosslinking agent, an initiator, a reducing agent, deionized water and cement. The composite solid-state capacitor is compatible with the existing building material processing and construction mode, and is easy to implement in a large scale and apply to engineering.

Description

Technical Field

[0001] This invention relates to the fields of building energy storage and electrochemical technology, and more specifically, to a composite solid-state structure capacitor based on in-situ polymerization and its preparation method. Background Technology

[0002] Existing cement-based structural capacitors mostly use porous cement-based materials or salt-containing pore solutions as solid electrolytes. Their ion transport mainly relies on limited free water and dissolved ions in the pores. The ion migration paths are dispersed and lack continuity, resulting in low overall ionic conductivity, which is insufficient to meet the requirements of high power density and rapid charge-discharge. Secondly, cement-based materials are easily affected by environmental factors such as wet-dry cycles and temperature changes during service. The moisture content in the pores fluctuates greatly, and the electrolyte performance deteriorates significantly over time, leading to unstable electrochemical performance. The authorized invention patent CN119495513B introduces soluble salts or liquid electrolytes to improve conductivity, but this method has drawbacks such as leakage risk, insufficient durability, and adverse effects on cement hydration and mechanical properties, limiting its engineering application.

[0003] To address the shortcomings of cement-based systems, such as poor energy storage and adverse effects on mechanical properties, authorized patent CN120199623B attempts to introduce polymer electrolytes into cement-based systems to improve their ion transport performance. However, existing technologies use post-implantation or physical blending methods to introduce polymers into cement pores, resulting in limited interfacial bonding between the polymer and the cement matrix. This makes it difficult to form a continuous and stable ion transport network at the pore scale, and the preparation process is complex and has poor reproducibility. Therefore, constructing cement-based solid electrolytes through in-situ polymerization could provide a new technical approach for achieving high-performance, long-life cement-based structural capacitors. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preparing a composite solid-state capacitor based on in-situ polymerization.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A composite solid-state capacitor based on in-situ polymerization includes two activated carbon-based electrodes and a cement-based solid electrolyte disposed between the two activated carbon-based electrodes. The activated carbon-based electrodes are made of nickel foam, active materials, conductive agents, binders and organic solvents; the cement-based solid electrolyte is made of polyethylene glycol, acrylic acid, NaOH, crosslinking agents, initiators, reducing agents, deionized water and cement.

[0007] Furthermore, the active material is activated carbon; the conductive agent is acetylene black; the binder is polyvinylidene fluoride; the organic solvent is N-methylpyrrolidone, and the ratio of the amount of organic solvent, active material, conductive agent and binder is (3~5) mL: (7~9) g: (0.5~1.5) g: (0.5~1.5) g.

[0008] Furthermore, the mass ratio of polyethylene glycol, acrylic acid, crosslinking agent, initiator, reducing agent and deionized water is (2~6):(0.2~3):(0.001~0.01):(0.003~0.03):(0.003~0.03):(30~60).

[0009] Furthermore, the crosslinking agent is N,N'-methylenebisacrylamide; the initiator is a water-soluble thermal initiator, consisting of one or a combination of ammonium persulfate or potassium persulfate; and the reducing agent is one or a combination of sodium bisulfite or sodium sulfite.

[0010] A method for fabricating a composite solid-state capacitor based on in-situ polymerization includes the following steps:

[0011] S1. Preparation of activated carbon-based electrodes;

[0012] S2. Preparation of cement-based in-situ polymerized composite solid electrolyte slurry;

[0013] S3. The electrolyte slurry is placed between two activated carbon-based electrodes to form a sandwich structure, and in-situ polymerization and cement hydration reaction are carried out under pressure to obtain a composite solid-state capacitor.

[0014] Further, in step S1, the active material, conductive agent and binder are mixed, an organic solvent is added and ground to form a uniform slurry; the slurry is loaded onto the surface of nickel foam by a rolling process, and after vacuum drying, an activated carbon-based electrode is obtained.

[0015] Furthermore, in step S1, the loading of activated carbon-based electrode slurry on the surface of the nickel foam is 10~30 mg / cm³. 2 The main roller speed of the rolling process is controlled at 0.5-5m / min, and the applied linear pressure ranges from 50-300N / cm. The foamed nickel is ultrasonically cleaned alternately with anhydrous ethanol and deionized water before being used for slurry loading. The slurry viscosity is 2000-8000mPa·s.

[0016] Further, in step S2, polyethylene glycol is dissolved in water to obtain a polyethylene glycol solution; acrylic acid is dissolved in water, and the pH of the solution is adjusted to neutral with NaOH before a crosslinking agent is added to obtain an acrylic composite solution; the polyethylene glycol solution, the acrylic composite solution, and cement are mixed and stirred evenly, and then an initiator solution and a reducing agent solution are added, and the mixture is stirred evenly to obtain a cement-based composite solid electrolyte slurry.

[0017] Further, in step S3, the cement-based composite solid electrolyte slurry obtained in step S2 is placed in a thin film mold, and the activated carbon-based electrode prepared in step S1 is placed on both sides of the cement-based composite solid electrolyte slurry; after standing, it is extruded; after extrusion, in-situ polymerization reaction and cement hydration reaction are carried out; then curing is performed to obtain a composite solid structure capacitor based on in-situ polymerization.

[0018] Furthermore, in step S3, the cement-based composite solid electrolyte slurry has an expansion of 120~160mm; the extrusion pressure is 0.5~5MPa, and the extrusion time is 10-20s; the thickness of the electrolyte layer under pressure is controlled to be 2~3mm; and the in-situ polymerization reaction is carried out at 40~60℃ for 1~3h.

[0019] In summary, the present invention has the following beneficial effects:

[0020] 1. This invention relates to an activated carbon-based electrode using nickel foam as the current collector. Nickel foam possesses a three-dimensional interconnected porous structure and excellent conductivity, effectively reducing the electrode's internal resistance. Activated carbon material has a large specific surface area, providing abundant electrical double-layer energy storage sites. Acetylene black, as a conductive agent, further improves the electron transport channels within the electrode. PVDF binder ensures the bonding strength between the active material and the current collector, enabling the electrode to maintain good structural stability and electrochemical consistency under pressure conditions and during long-term operation. The activated carbon-based electrode also features widely available and inexpensive raw materials.

[0021] 2. This invention introduces a composite system of polyethylene glycol (PEG) and acrylic acid (AA) into a cement-based solid electrolyte, and achieves in-situ polymerization during the curing process. PEG molecules possess excellent hydrophilicity and a flexible chain structure; their introduction can regulate the pore structure of cement-based materials, promoting the formation of more fine and uniformly distributed effective pores. Acrylic acid, under the action of initiators and reducing agents, polymerizes in situ to form a polyacrylic acid network. The carboxyl functional groups abundant in its molecular chains enhance the adsorption and fixation capacity for ions, while simultaneously constructing continuous ion migration channels within the pores of the cement-based material.

[0022] The synergistic effect of polyethylene glycol and acrylic acid enables the formation of a multi-scale, interconnected ion transport network within the cement-based solid electrolyte. This effectively improves the ionic conductivity of the solid electrolyte without significantly weakening the mechanical properties and pressure resistance of cement-based materials, thereby overcoming the technical problem of limited ion migration in traditional cement-based electrolytes.

[0023] 3. The electrolyte layer of this invention is thin and uniformly distributed, resulting in a short ion transport path and superior electrochemical performance of the capacitor. By directly placing the cement-based composite solid electrolyte between two activated carbon-based electrodes and performing in-situ polymerization and curing, this invention utilizes constant pressure extrusion to effectively control and uniformly distribute the electrolyte layer thickness, significantly shortening the ion transport path between the electrodes and thus reducing the capacitor's internal resistance. The resulting composite solid capacitor has a wide stable operating voltage window and can achieve high energy density and power density under relatively thin structural conditions.

[0024] 4. The composite solid-state capacitor of this invention is prepared using in-situ polymerization and cement hydration processes. The process is simple, highly adaptable, and compatible with existing building material processing and construction methods, facilitating large-scale implementation and engineering applications. Furthermore, this capacitor possesses solid-state, stable, and pressure-bearing structural characteristics, allowing it to be designed as a functional unit combining structural load-bearing and energy storage capabilities. Practical application verification results show that multiple capacitors connected in series can provide continuous and stable power output to small electrical devices, indicating its suitability for low-power electronic devices, sensors, or emergency power supply applications in building environments. Attached Figure Description

[0025] Figure 1 Cyclic voltammetry (CV) curves of the cement-based composite solid-state structure capacitor prepared in Example 1;

[0026] Figure 2 The cement-based composite solid-state capacitor prepared in Example 1 operates at a current density of 1 mA / cm². 2 Constant current charge-discharge (GCD) curves under these conditions;

[0027] Figure 3 Electrochemical impedance spectroscopy (EIS) of the cement-based composite solid-state structure capacitor prepared in Example 1.

[0028] Figure 4 Cyclic voltammetry (CV) curves of the cement-based composite solid-state structure capacitor prepared in Example 2;

[0029] Figure 5 The cement-based composite solid-state capacitor prepared in Example 2 operates at a current density of 1 mA / cm². 2 Constant current charge-discharge (GCD) curves under these conditions;

[0030] Figure 6 Electrochemical impedance spectroscopy (EIS) curves of the cement-based composite solid-state structure capacitor prepared in Example 2;

[0031] Figure 7 Cyclic voltammetry (CV) curves of the cement-based composite solid-state structure capacitor prepared in Example 3;

[0032] Figure 8 The cement-based composite solid-state capacitor prepared in Example 3 operates at a current density of 1 mA / cm². 2 Constant current charge-discharge (GCD) curves under these conditions;

[0033] Figure 9 Electrochemical impedance spectroscopy (EIS) curves of the cement-based composite solid-state structure capacitor prepared in Example 3;

[0034] Figure 10 Cyclic voltammetry (CV) curves of the cement-based composite solid-state structure capacitor prepared in Example 4;

[0035] Figure 11 The cement-based composite solid-state capacitor prepared in Example 4 operates at a current density of 1 mA / cm². 2 Constant current charge-discharge (GCD) curves under these conditions;

[0036] Figure 12 Electrochemical impedance spectroscopy (EIS) curves of the cement-based composite solid-state structure capacitor prepared in Example 4;

[0037] Figure 13 Cyclic voltammetry (CV) curves of the cement-based composite solid-state structure capacitor prepared in Example 5;

[0038] Figure 14 The cement-based composite solid-state capacitor prepared in Example 5 operates at a current density of 1 mA / cm². 2 Constant current charge-discharge (GCD) curves under these conditions;

[0039] Figure 15 Electrochemical impedance spectroscopy (EIS) curves of the cement-based composite solid-state structure capacitor prepared in Example 5;

[0040] Figure 16 Cyclic voltammetry (CV) curves of the cement-based composite solid-state structure capacitor prepared in Comparative Example 1;

[0041] Figure 17 The cement-based composite solid-state capacitor prepared for Comparative Example 1 was tested at a current density of 1 mA / cm². 2 Constant current charge-discharge (GCD) curves under these conditions;

[0042] Figure 18 Electrochemical impedance spectroscopy (EIS) curves of the cement-based composite solid-state structure capacitor prepared for Comparative Example 1;

[0043] Figure 19Field emission scanning electron microscope (SEM) images of Examples 1-5 and Comparative Example 1 (a corresponds to Example 1, b corresponds to Example 2, c corresponds to Example 3, d corresponds to Example 4, e corresponds to Example 5, and f corresponds to Comparative Example 1).

[0044] Figure 20 A schematic diagram showing five structural capacitors connected in series to power a small electric fan. Detailed Implementation

[0045] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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.

[0046] This invention provides a method for preparing a composite solid-state capacitor based on in-situ polymerization, specifically including the following steps:

[0047] Step 1: Preparation of activated carbon-based electrode:

[0048] Nickel foam was used as a current collector with a size of (8~12) mm × (10~20) mm. The nickel foam was ultrasonically cleaned alternately with anhydrous ethanol and deionized water for 10 minutes each time. The cleaned nickel foam was then placed in an oven to dry for later use.

[0049] Weigh out the active material, conductive agent, and binder (preferably, the active material is activated carbon, the conductive agent is acetylene black, and the binder is polyvinylidene fluoride), and mix and grind them thoroughly in a mortar. The activated carbon (with a specific surface area greater than 1000 m²) should be... 2 / g), acetylene black (particle size 35-45nm, surface area 70~85m²), 2 The mass ratio of N-methylpyrrolidone (NMP) to polyvinylidene fluoride (molecular weight 1.1 million, particle size <100μm) is (7~9):(0.5~1.5):(0.5~1.5); N-methylpyrrolidone (NMP) is added to the mixed powder in the mortar, and the ratio of N-methylpyrrolidone (NMP) to the mixed powder is (3~5)mL:(8~12)g. Grind for 8~12min to obtain a uniform electrode slurry with a viscosity of 2000-8000mPa·s.

[0050] The above electrode paste was drop-coated onto a nickel foam surface measuring (8~12) mm × (10~20) mm, with an activated carbon-based electrode paste loading of 10~30 mg / cm³ on the nickel foam surface. 2The nickel foam is rolled and leveled using a roller press. The main roller speed of the rolling process is controlled at 0.5-5 m / min, and the applied linear pressure ranges from 50-300 N / cm. The nickel foam is then dried in a vacuum drying oven at 50-80℃ for 6-24 hours to obtain an activated carbon-based electrode.

[0051] Step 2: Preparation of in-situ polymerized cement-based composite solid electrolyte:

[0052] Polyethylene glycol (molecular weight 4000-8000 Da) was dissolved in deionized water at a mass ratio of (2~6):(10~20). The solution was stirred at room temperature until completely dissolved to obtain a polyethylene glycol solution.

[0053] Acrylic acid is dissolved in deionized water to obtain an acrylic acid solution. The mass ratio of acrylic acid to deionized water is (0.2~3):(10~20). The pH of the acrylic acid solution is adjusted to neutral conditions using flake sodium hydroxide to obtain a mixed solution. A crosslinking agent is added to the mixed solution. The mass ratio of acrylic acid to crosslinking agent is (0.2~3):(0.001~0.01). Preferably, the crosslinking agent is N,N'-methylenebisacrylamide (MBA). After complete stirring, an acrylic acid composite solution is obtained. The mass ratio of polyethylene glycol, acrylic acid, initiator, and reducing agent is (2~6):(0.2~3):(0.003~0.03):(0.003~0.03). The initiator is added to deionized water to obtain an initiator solution. Preferably, the initiator is ammonium persulfate, and the mass ratio of initiator to deionized water is (0.003~0.03):(5~10). The reducing agent is dissolved in deionized water to obtain a reducing agent solution. Preferably, the reducing agent is sodium bisulfite, and the mass ratio of reducing agent to deionized water is (0.003~0.03):(5~10).

[0054] The above-mentioned polyethylene glycol solution and acrylic composite solution were added sequentially to 70-90g of cement that had been weighed, and the mixture was stirred evenly. Then, the above-prepared ammonium persulfate solution and sodium bisulfite solution were added separately, and the mixture was stirred for 8-12 minutes to obtain a cement-based composite solid electrolyte slurry with a spread of 120-160mm.

[0055] Step 3: Assembly and curing of composite solid-state capacitors:

[0056] Take the cement-based composite solid electrolyte slurry obtained in step two and place it in a thin film mold. Place the activated carbon-based electrodes prepared in step one on both sides of the solid electrolyte slurry. After standing for 1-3 hours, apply a pressure of 0.5-5 MPa to the composite material and hold it for 10-20 seconds. Under pressure, control the thickness of the electrolyte layer to 2-3 mm. After extrusion, place the composite material in a vacuum drying oven at 40-60℃ for 1 hour to cure it. Remove excess composite solid electrolyte from the outside of the cement, and finally obtain the in-situ polymerized composite solid structure capacitor.

[0057] Example 1

[0058] A method for fabricating a composite solid-state capacitor based on in-situ polymerization, comprising the following specific steps:

[0059] (1) Preparation of activated carbon-based electrodes

[0060] Take 10mm×15mm nickel foam as the current collector, and use anhydrous ethanol and deionized water alternately for ultrasonic cleaning, 10 minutes each time, to remove oil and impurities from its surface. After cleaning, place it in an oven to dry for later use.

[0061] Weigh 8g of activated carbon, 1g of acetylene black and 1g of polyvinylidene fluoride, place them in a mortar and mix and grind them thoroughly; then add 4mL of N-methylpyrrolidone to the mixed powder and continue grinding for 10min to obtain a uniform electrode slurry.

[0062] The obtained slurry was uniformly drop-coated onto the surface of nickel foam, with a drop-coating area of ​​10 mm × 10 mm. The loading of the activated carbon-based electrode slurry on the nickel foam surface was 21.4 mg / cm³. 2 The 10mm × 5mm uncoated nickel foam electrode was used as the lead-out terminal for external testing. After being rolled and leveled by a roller press, it was dried in a vacuum drying oven at 60℃ for 12 hours to obtain an activated carbon-based electrode.

[0063] (2) Preparation of in-situ polymerized cement-based composite solid electrolyte

[0064] Weigh 4g of polyethylene glycol and add it to 10g of deionized water. Stir at room temperature until completely dissolved to obtain a polyethylene glycol solution.

[0065] 0.36 g of acrylic acid was dissolved in 10 g of deionized water, and the pH of the solution was adjusted to 7.0 by mixing with NaOH. Then, 1.08 mg of crosslinking agent N,N'-methylenebisacrylamide was added, and the mixture was stirred thoroughly to obtain an acrylic acid composite solution. 3.6 mg of ammonium persulfate was dissolved in 10 g of deionized water to obtain an ammonium persulfate solution, and 3.6 mg of sodium bisulfite was dissolved in 10 g of deionized water to obtain a sodium bisulfite solution.

[0066] Weigh 80g of cement (P·I 52.5), add polyethylene glycol solution and acrylic acid composite solution to the cement in sequence, stir evenly, then add ammonium persulfate solution and sodium bisulfite solution respectively, and continue stirring for 10 minutes to obtain a cement-based composite solid electrolyte slurry with good fluidity.

[0067] (3) Assembly and curing of composite solid-state capacitors

[0068] The cement-based composite solid electrolyte obtained in step (2) was placed in a 10mm×10mm×4mm film mold, and the activated carbon-based electrode from step (1) was placed on both sides of the cement-based composite solid electrolyte to form a "sandwich" structure. After standing for 1 hour, it was placed on a press and squeezed for 10 seconds under a pressure of 0.5MPa to improve the interfacial contact between the electrode and the electrolyte, so that the thickness of the middle electrolyte was kept within the range of 2-3mm. After extrusion, the resulting structure was placed in a 50℃ vacuum drying oven to allow polyethylene glycol and acrylic acid to undergo in-situ polymerization for 1 hour to form an in-situ polymerized composite material. Then it was transferred to a standard curing box for curing to allow the cement to undergo hydration and gradually solidify, and the excess cement-based composite solid electrolyte on the outside was removed, finally obtaining a composite solid structure capacitor based on in-situ polymerization.

[0069] Example 2

[0070] The composite solid-state capacitor was prepared according to the method of Example 1, except that in step (2), 0.72g of acrylic acid was dissolved in 10g of deionized water and mixed with flake NaOH to adjust the pH of the solution to 7.0. Then, 2.16mg of crosslinking agent N,N'-methylenebisacrylamide was added and stirred thoroughly to obtain an acrylic acid composite solution. 7.2mg of ammonium persulfate was dissolved in 10g of deionized water to obtain an ammonium persulfate solution, and 7.2mg of sodium bisulfite was dissolved in 10g of deionized water to obtain a sodium bisulfite solution.

[0071] Example 3

[0072] The composite solid-state capacitor was prepared according to the method of Example 1, except that in step (2), 1.44 g of acrylic acid was dissolved in 10 g of deionized water and mixed with flake NaOH to adjust the pH of the solution to 7.0. Then, 4.32 mg of crosslinking agent N,N'-methylenebisacrylamide was added and stirred thoroughly to obtain an acrylic acid composite solution. 14.4 mg of ammonium persulfate was dissolved in 5 g of deionized water to obtain an ammonium persulfate solution, and 14.4 mg of sodium bisulfite was dissolved in 5 g of deionized water to obtain a sodium bisulfite solution.

[0073] Example 4

[0074] The composite solid-state capacitor was prepared according to the method of Example 1, except that in step (2), 2.16 g of acrylic acid was dissolved in 10 g of deionized water and mixed with 1.2 g of flake NaOH to adjust the pH of the solution to 7.0. Then, 6.48 mg of crosslinking agent N,N'-methylenebisacrylamide was added and stirred thoroughly to obtain an acrylic acid composite solution. 21.6 mg of ammonium persulfate was dissolved in 5 g of deionized water to obtain an ammonium persulfate solution, and 21.6 mg of sodium bisulfite was dissolved in 5 g of deionized water to obtain a sodium bisulfite solution.

[0075] Example 5

[0076] The composite solid-state capacitor was prepared according to the method in Example 1, except that in step (2), 2.88 g of acrylic acid was dissolved in 10 g of deionized water and mixed with flake NaOH to adjust the pH of the solution to 7.0. Then, 8.64 mg of crosslinking agent N,N'-methylenebisacrylamide was added and stirred thoroughly to obtain an acrylic acid composite solution. 28.8 mg of ammonium persulfate was dissolved in 10 g of deionized water to obtain an ammonium persulfate solution, and 28.8 mg of sodium bisulfite was dissolved in 10 g of deionized water to obtain a sodium bisulfite solution.

[0077] Example 6

[0078] (1) Preparation of activated carbon-based electrodes

[0079] Take 10mm×15mm nickel foam as the current collector, and use anhydrous ethanol and deionized water alternately for ultrasonic cleaning, 10 minutes each time, to remove oil and impurities from its surface. After cleaning, place it in an oven to dry for later use.

[0080] Weigh 8g of activated carbon, 1g of acetylene black and 1g of polyvinylidene fluoride, place them in a mortar and mix and grind them thoroughly; then add 4mL of N-methylpyrrolidone to the mixed powder and continue grinding for 10min to obtain a uniform electrode slurry.

[0081] The obtained slurry was uniformly drop-coated onto the surface of nickel foam, with a drop-coating area of ​​10 mm × 10 mm. The loading of the activated carbon-based electrode slurry on the nickel foam surface was 21.4 mg / cm². 2 The 10mm × 5mm uncoated nickel foam electrode was used as the lead-out terminal for external testing. After being rolled and leveled by a roller press, it was dried in a vacuum drying oven at 60℃ for 12 hours to obtain an activated carbon-based electrode.

[0082] (2) Preparation of in-situ polymerized cement-based composite solid electrolyte

[0083] Weigh 4g of polyethylene glycol and add it to 10g of deionized water. Stir at room temperature until completely dissolved to obtain a polyethylene glycol solution.

[0084] Dissolve 3g of acrylic acid in 10g of deionized water and mix with flake NaOH to adjust the pH of the solution to 7.0. Then add 9mg of crosslinking agent N,N'-methylenebisacrylamide and stir thoroughly to obtain an acrylic acid composite solution. Dissolve 3mg of ammonium persulfate in 10g of deionized water to obtain an ammonium persulfate solution, and dissolve 3mg of sodium bisulfite in 10g of deionized water to obtain a sodium bisulfite solution.

[0085] Weigh 80g of cement, add polyethylene glycol solution and acrylic composite solution to the cement in sequence, stir evenly, then add ammonium persulfate solution and sodium bisulfite solution respectively, and continue stirring for 10 minutes to obtain a cement-based composite solid electrolyte slurry with good fluidity.

[0086] (3) Assembly and curing of composite solid-state capacitors

[0087] The cement-based composite solid electrolyte obtained in step (2) was placed in a 10mm×10mm×4mm film mold, and the activated carbon-based electrode from step (1) was placed on both sides of the cement-based composite solid electrolyte to form a "sandwich" structure. After standing for 1 hour, it was placed on a press and squeezed for 10 seconds under a pressure of 0.5MPa to improve the interfacial contact between the electrode and the electrolyte, so that the thickness of the middle electrolyte was kept within the range of 2-3mm. After extrusion, the resulting structure was placed in a 50℃ vacuum drying oven to allow polyethylene glycol and acrylic acid to undergo in-situ polymerization for 1 hour to form an in-situ polymerized composite material. Then it was transferred to a standard curing box for curing to allow the cement to undergo hydration and gradually solidify, and the excess cement-based composite solid electrolyte on the outside was removed, finally obtaining a composite solid structure capacitor based on in-situ polymerization.

[0088] Example 7

[0089] Example 7 further verifies the application potential of the electrochemical energy storage device in Example 6 in practical energy consumption scenarios. Specifically, Example 7 uses the cement-based supercapacitor prepared in Example 6 as the energy storage unit. The dimensions of a single capacitor device are 10mm × 10mm × 4mm, employing a sandwich structure. Five of these capacitor devices are connected in series via wires to form a series energy storage module, such as... Figure 20 The diagram shows five structural capacitors connected in series to power a small electric fan. The series connection is achieved by connecting the positive and negative terminals of adjacent capacitors sequentially, thus superimposing the output voltages. Before use, the series energy storage module is tested at 20mA / cm. 2 The module was charged under a constant current density until the voltage reached 5V, after which the charging power was disconnected. The fully charged series energy storage module was then connected to a small DC electric fan as a load. The rated operating voltage of the electric fan was 3-5V, and the rated power was 0.3-0.5W.

[0090] Under the above conditions, the series energy storage module can continuously power a small electric fan for about 30 seconds, indicating that the electrochemical energy storage device of the present invention has a certain actual energy output capability and stable discharge characteristics, and can meet the short-term power supply needs of low-power electrical devices.

[0091] In summary, the composite solid-state capacitor based on in-situ polymerization prepared by this invention has excellent electrochemical performance and good mechanical properties.

[0092] Comparative Example 1

[0093] The capacitor was prepared according to the method of Example 1, except that in step (2), the acrylic composite solution, ammonium persulfate solution, and sodium bisulfite solution were not added to Comparative Example 1; 4g of polyethylene glycol was weighed and added to 10g of deionized water, and stirred at room temperature until completely dissolved to obtain a polyethylene glycol solution. 80g of cement was weighed, and the polyethylene glycol solution was added to the cement. After stirring evenly, a cement-based composite solid electrolyte slurry with good fluidity was obtained.

[0094] Results analysis:

[0095] Figure 1 The cyclic voltammetry (CV) curves of the cement-based composite solid-state capacitor prepared in Example 1 are shown. It can be seen that the CV curves of Example 1 maintain a relatively stable spindle shape within the test voltage window, without significant deformation, indicating that the device has good electrochemical stability.

[0096] Figure 2 The cement-based composite solid-state capacitor prepared in Example 1 operates at a current density of 1 mA / cm². 2 The constant current charge-discharge (GCD) curves are shown in the figure. As can be seen from the figure, the charge-discharge curves of Example 1 exhibit good overall symmetry, indicating that the device has high coulombic efficiency and stable charge-discharge behavior, with a discharge time of 81s.

[0097] Figure 3 The electrochemical impedance spectroscopy (EIS) results are shown for the cement-based composite solid-state capacitor prepared in Example 1. In the high-frequency region, the intercept of the curve on the real axis is approximately 6 Ω, indicating a low internal resistance of about 6 Ω. In the mid-frequency region, the corresponding semicircle diameter is small, indicating a low charge transfer impedance, which is beneficial for electron and ion transport. In the low-frequency region, the slope of the curve in Example 1 is closer to the vertical direction, indicating that it has superior ion diffusion characteristics.

[0098] Figure 4The cyclic voltammetry (CV) curves of the cement-based composite solid-state capacitor prepared in Example 2 show that its overall morphology is stable and no obvious distortion occurs, indicating that the device has good electrochemical stability within the test voltage range. The voltage changes in both forward and reverse scanning processes show consistent trends, indicating stable charge storage behavior. The increased curve coverage area indicates a larger capacitance.

[0099] Figure 5 The cement-based composite solid-state capacitor prepared in Example 2 operates at a current density of 1 mA / cm². 2 The constant current charge-discharge (GCD) curve under the given conditions showed that the discharge time was extended to 110 s, indicating that the composite solid capacitor prepared in Example 2 has superior energy storage performance.

[0100] Figure 6 The image shows the electrochemical impedance spectroscopy (EIS) curves of the cement-based composite solid-state capacitor prepared in Example 2. In the high-frequency region, the intercept on the real axis of the curve in Example 2 is 1.1 Ω, indicating that its electrolyte has a low internal resistance. In the mid-to-low frequency region, the semicircle diameter of the curve represents a charge transfer resistance of approximately 5 Ω, indicating that the charge transfer capability and ion diffusion of this device are both reduced.

[0101] Figure 7 The cyclic voltammetry (CV) curves of the cement-based composite solid-state capacitor prepared in Example 3 are shown. Its overall morphology is stable, exhibiting relatively consistent charge storage behavior.

[0102] Figure 8 The cement-based composite solid-state capacitor prepared in Example 3 operates at a current density of 1 mA / cm². 2 The constant current charge-discharge (GCD) curves under the given conditions show stable charge-discharge behavior, with continuous and smooth curves, and the discharge time is extended to 120s, indicating that the device has good charge-discharge performance.

[0103] Figure 9 The image shows the electrochemical impedance spectroscopy (EIS) curve of the cement-based composite solid-state capacitor prepared in Example 3. The intercept on the real axis is approximately 5 Ω, indicating that the internal resistance of the system is low, approximately 5 Ω. This demonstrates good ion diffusion performance.

[0104] Figure 10 The cyclic voltammetry (CV) curve of the cement-based composite solid-state capacitor prepared in Example 4 shows that the curve is distorted near 1V, indicating that a hydrogen evolution reaction occurs near 1V, resulting in reduced electrochemical stability.

[0105] Figure 11 The cement-based composite solid-state capacitor prepared in Example 4 operates at a current density of 1 mA / cm². 2The constant current charge-discharge (GCD) curves under the given conditions show that the overall charge-discharge curves are stable and the discharge curves are longer, with a discharge time of 100s, demonstrating good charge-discharge stability.

[0106] Figure 12 The electrochemical impedance spectroscopy (EIS) curve of the cement-based composite solid structure capacitor prepared in Example 4 shows that the intercept of the curve on the real axis increases to 11Ω in the high-frequency region, and the slope of the curve increases in the low-frequency region, indicating that the device has excellent diffusion behavior.

[0107] Figure 13 The cyclic voltammetry (CV) curves of the cement-based composite solid-state structure capacitor prepared in Example 5 show a smooth overall morphology, indicating stable charge-discharge characteristics.

[0108] Figure 14 The cement-based composite solid-state capacitor prepared in Example 5 operates at a current density of 1 mA / cm². 2 The constant current charge-discharge (GCD) curves were smooth and symmetrical, with a discharge time of 60s, indicating that the energy storage capacity of the device prepared in Example 5 was significantly reduced.

[0109] Figure 15 The electrochemical impedance spectroscopy (EIS) curves of the cement-based composite solid-state capacitor device prepared in Example 5 show that in the high-frequency region, the intercept on the real axis increases to 7Ω, and in the mid-frequency region, the semicircle diameter is approximately 10Ω. In the low-frequency region, the slope is relatively gentle, indicating that the charge transfer and ion diffusion capabilities of the device are moderate.

[0110] Figure 16 The cyclic voltammetry (CV) curve of the cement-based composite solid-state structure capacitor prepared for Comparative Example 1 shows significant overall deformation, indicating that its charge storage capacity is limited under the same conditions, thus highlighting the technical effect of the embodiment of the present invention.

[0111] Figure 17 The cement-based composite solid-state capacitor prepared for Comparative Example 1 was tested at a current density of 1 mA / cm². 2 The constant current charge-discharge (GCD) curves under the given conditions show that the overall symmetry of the curves is slightly poor and the discharge time is relatively short, indicating that the energy storage capacity is limited, thereby verifying the feasibility of the embodiments of the present invention.

[0112] Figure 18 The electrochemical impedance spectroscopy (EIS) curve of the cement-based composite solid structure capacitor prepared in Comparative Example 1 shows a slightly larger high-frequency intercept and a larger semicircle diameter, indicating that its charge transfer impedance and ion diffusion capability are lower than those of the embodiments of the present invention, thus verifying the technical effect.

[0113] The results of the cyclic voltammetry, constant current charge-discharge, and electrochemical impedance spectroscopy tests show that the devices in Examples 1-5 of this invention exhibit stable charge-discharge behavior, charge storage capacity, and reasonable charge transfer characteristics. In contrast, Comparative Example 1 shows lower energy storage capacity and charge transfer performance under the same test conditions, indicating that the present invention significantly improves electrochemical performance through in-situ polymerization design and optimization of cement-based composite solid electrolytes, and has practical application potential.

[0114] Figure 19 The images shown are field emission scanning electron microscope (SEM) images of Examples 1-5 and Comparative Example 1 (a corresponds to Example 1, b to Example 2, c to Example 3, d to Example 4, e to Example 5, and f to Comparative Example 1). The SEM image of Comparative Example 1 shows that the material surface has a small number of pores that are sparsely distributed, some pores are not interconnected, the microstructure continuity is low, and a small number of microcracks exist on the surface. With increasing polymer content, the SEM images of Examples 1-5 show a gradual increase in the number of pores, a gradual increase in pore size, a more uniform distribution, and enhanced interconnectivity. The pore structure of Example 1 is slightly increased; the number and size of pores in Examples 2-3 further increase, forming a continuous pore network; the pores in Examples 4-5 further increase in size and are uniformly distributed, with a smooth surface and stable structure.

[0115] Table 1 shows the compressive strength test results of the cement-based composite solid electrolytes prepared in Examples 1-4 and Comparative Example 1 at 7 days and 28 days. Table 2 shows the total pore volume of the cement-based composite solid electrolytes prepared in Examples 1-4 and Comparative Example 1.

[0116] Table 1

[0117]

[0118] Table 2

[0119]

[0120] In Examples 1-4 and Comparative Example 1 above, the compressive strength test was conducted according to GB / T 17671 "Test Method for Strength of Cement Mortar". For the mechanical property test, the cement-based electrolyte mold dimensions were 40mm × 40mm × 40mm. A YAW-300E fully automatic pressure testing machine was used, with a loading speed of 2.4kN / s. Six samples were tested per group, and the average value was taken. The pore volume of the cement-based electrolyte was tested using the mercury intrusion porosimetry method according to ISO 15901-1 standard. The testing equipment was an automatic mercury intrusion porosimetry porosimetry analyzer.

[0121] Electrochemical performance testing methods: For electrochemical performance testing, the structural supercapacitor measures 10mm × 10mm in size and approximately 3mm in thickness. A CHI660C electrochemical workstation was used to test the cyclic voltammetry (CV) of the composite solid-state capacitor. The voltage window was 0–1.0V, and the scan rate was 10mV / s. Electrochemical impedance spectroscopy (EIS) was performed in the frequency range of 100kHz–0.01Hz. Galvanostatic charge-discharge (GCD) was conducted at a current density of 1mA / cm². 2 .

[0122] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A composite solid-state capacitor based on in-situ polymerization, characterized in that, It includes two activated carbon-based electrodes and a cement-based solid electrolyte disposed between the two activated carbon-based electrodes. The activated carbon-based electrodes are made of nickel foam, active materials, conductive agents, binders and organic solvents; the cement-based solid electrolyte is made of polyethylene glycol, acrylic acid, NaOH, crosslinking agents, initiators, reducing agents, deionized water and cement.

2. A composite solid-state structure capacitor based on in-situ polymerization according to claim 1, characterized in that, The active material is activated carbon; the conductive agent is acetylene black; the binder is polyvinylidene fluoride; the organic solvent is N-methylpyrrolidone, and the ratio of organic solvent, active material, conductive agent and binder is (3~5) mL: (7~9) g: (0.5~1.5) g: (0.5~1.5) g.

3. A composite solid-state structure capacitor based on in-situ polymerization according to claim 2, characterized in that, The mass ratio of polyethylene glycol, acrylic acid, crosslinking agent, NaOH, initiator, reducing agent and deionized water is (2~6):(0.2~3):(0.001~0.01):(0.003~0.03):(0.003~0.03):(30~60).

4. A composite solid-state structure capacitor based on in-situ polymerization according to claim 3, characterized in that, The crosslinking agent is N,N'-methylenebisacrylamide; the initiator is a water-soluble thermal initiator, consisting of one or a combination of ammonium persulfate or potassium persulfate; the reducing agent is one or a combination of sodium bisulfite or sodium sulfite.

5. A method for preparing a composite solid-state capacitor based on in-situ polymerization according to claim 4, characterized in that, Includes the following steps: S1. Preparation of activated carbon-based electrodes; S2. Preparation of cement-based in-situ polymerized composite solid electrolyte slurry; S3. The electrolyte slurry is placed between two activated carbon-based electrodes to form a sandwich structure, and in-situ polymerization and cement hydration reaction are carried out under pressure to obtain a composite solid-state capacitor.

6. A method for preparing a composite solid-state structure capacitor based on in-situ polymerization according to claim 5, characterized in that, In step S1, the active material, conductive agent and binder are mixed, an organic solvent is added and the mixture is ground to form a uniform slurry; the slurry is loaded onto the surface of nickel foam by a rolling process and then dried under vacuum to obtain an activated carbon-based electrode.

7. The method for preparing a composite solid-state structure capacitor based on in-situ polymerization according to claim 5, characterized in that, In step S1, the loading of activated carbon-based electrode slurry on the surface of nickel foam is 10~30 mg / cm³. 2 The main roller linear speed of the rolling process is controlled at 0.5-5m / min, and the applied linear pressure ranges from 50-300N / cm. The foamed nickel is ultrasonically cleaned alternately with anhydrous ethanol and deionized water before being used for slurry loading. The slurry viscosity is 2000-8000mPa·s.

8. A method for preparing a composite solid-state capacitor based on in-situ polymerization according to claim 5, characterized in that, In step S2, polyethylene glycol is dissolved in water to obtain a polyethylene glycol solution; acrylic acid is dissolved in water, and the pH of the solution is adjusted to neutral with NaOH before a crosslinking agent is added to obtain an acrylic composite solution; the polyethylene glycol solution, the acrylic composite solution, and cement are mixed and stirred evenly, and then an initiator solution and a reducing agent solution are added and stirred evenly to obtain a cement-based composite solid electrolyte slurry.

9. A method for preparing a composite solid-state capacitor based on in-situ polymerization according to claim 5, characterized in that, In step S3, the cement-based composite solid electrolyte slurry obtained in step S2 is placed in a thin film mold, and the activated carbon-based electrode prepared in step S1 is placed on both sides of the cement-based composite solid electrolyte slurry; after standing, it is extruded; after extrusion, in-situ polymerization reaction and cement hydration reaction are carried out; then curing is performed to obtain a composite solid structure capacitor based on in-situ polymerization.

10. A method for preparing a composite solid-state structure capacitor based on in-situ polymerization according to claim 9, characterized in that, In step S3, the cement-based composite solid electrolyte slurry has an expansion of 120~160mm; the extrusion pressure is 0.5~5MPa, and the extrusion time is 10-20s; the thickness of the electrolyte layer under pressure is controlled to be 2~3mm; and the in-situ polymerization reaction is carried out at 40~60℃ for 1~3h.

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